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Sample records for photoelectrochemical cells based

  1. Apollony photonic sponge based photoelectrochemical solar cells.

    PubMed

    Ramiro-Manzano, Fernando; Atienzar, Pedro; Rodriguez, Isabelle; Meseguer, Francisco; Garcia, Hermenegildo; Corma, Avelino

    2007-01-21

    We have developed a quasi-fractal colloidal crystal to localize efficiently photons in a very broad optical spectral range; it has been applied to prepare dye sensitized photoelectrochemical solar (PES) cells able to harvest very efficiently photons from the ultraviolet (UV) and the visible (VIS) regions of the solar spectrum.

  2. Apollony photonic sponge based photoelectrochemical solar cells.

    PubMed

    Ramiro-Manzano, Fernando; Atienzar, Pedro; Rodriguez, Isabelle; Meseguer, Francisco; Garcia, Hermenegildo; Corma, Avelino

    2007-01-21

    We have developed a quasi-fractal colloidal crystal to localize efficiently photons in a very broad optical spectral range; it has been applied to prepare dye sensitized photoelectrochemical solar (PES) cells able to harvest very efficiently photons from the ultraviolet (UV) and the visible (VIS) regions of the solar spectrum. PMID:17299626

  3. Photoelectrochemical cell

    DOEpatents

    Rauh, R. David; Boudreau, Robert A.

    1983-06-14

    A photoelectrochemical cell comprising a sealed container having a light-transmitting window for admitting light into the container across a light-admitting plane, an electrolyte in the container, a photoelectrode in the container having a light-absorbing surface arranged to receive light from the window and in contact with the electrolyte, the surface having a plurality of spaced portions oblique to the plane, each portion having dimensions at least an order of magnitude larger than the maximum wavelength of incident sunlight, the total surface area of the surface being larger than the area of the plane bounded by the container, and a counter electrode in the container in contact with the electrolyte.

  4. Nanocomposite Photoelectrochemical Cells

    NASA Technical Reports Server (NTRS)

    Narayan, Sri R.; Kindler, Andrew; Whitacre, Jay F.

    2007-01-01

    Improved, solid-state photoelectrochemical cells for converting solar radiation to electricity have been proposed. (In general, photoelectrochemical cells convert incident light to electricity through electrochemical reactions.) It is predicted that in comparison with state-of-the-art photoelectrochemical cells, these cells will be found to operate with greater solar-to-electric energy-conversion efficiencies.

  5. Photoelectrochemical Solar Cells.

    ERIC Educational Resources Information Center

    McDevitt, John T.

    1984-01-01

    This introduction to photoelectrochemical (PEC) cells reviews topics pertaining to solar energy conversion and demonstrates the ease with which a working PEC cell can be prepared with n-type silicon as the photoanode and a platinum counter electrode (both immersed in ethanolic ferrocene/ferricenium solutions). Experiments using the cell are…

  6. Tris(hydroxymethyl)aminomethane photooxidation on titania based photoanodes and its implication for photoelectrochemical biofuel cells

    NASA Astrophysics Data System (ADS)

    Filipiak, Marcin S.; Zloczewska, Adrianna; Grzeskowiak, Piotr; Lynch, Robert; Jönsson-Niedziolka, Martin

    2015-09-01

    In many photoelectrochemical biofuel cells tris(hydroxymethyl)aminomethane (TRIS) is used a buffer. We show that TRIS can be readily photooxidised on titania electrodes. Combining a titania nanotube photoanode in a TRIS buffer with an air-breathing enzymatic biocathode we construct a relatively efficient photoelectrochemical biofuel cell using the TRIS buffer as fuel. This shows both the prospect of using air-breathing bio-cathodes in this kind of cells, but more importantly, shows the need for caution when using TRIS as buffer in photoelectrochemical applications.

  7. Superlattice photoelectrodes for photoelectrochemical cells

    DOEpatents

    Nozik, A.J.

    1985-07-03

    The application of superlattice semiconductors as photoelectrodes in photoelectrochemical energy conversion processes is described. The invention is comprised of a multiple quantum well, or superlattice, semiconductor positioned on a plate and encapsulated in an insulation material, except the top surface, which is left exposed. An opening in insulation exposes a portion of the plate. When the photoelectrochemical cell is immersed in a liquid electrolyte and exposed to solar radiation, a redox reaction occurs, producing gases such as hydrogen and oxygen from a water electrolyte, which bubble off the cathode and anode portions of the cell. (LEW)

  8. High-performance photoelectrochemical cells based on a binuclear ruthenium catalyst for visible-light-driven water oxidation.

    PubMed

    Zhang, Linlin; Gao, Yan; Ding, Xin; Yu, Ze; Sun, Licheng

    2014-10-01

    Two photoanodes based on a binuclear (2) and a mononuclear ruthenium (3) water oxidation catalysts were assembled in combination with a molecular photosensitizer (1) by using a co-adsorption method. The anodes were used in dye-sensitized photoelectrochemical cells (DS-PECs) for visible-light-driven water splitting. A DS-PEC device using TiO2 (1+2) as working electrode (WE) exhibits better performance than TiO2 (1+3) as WE in light-driven water splitting. Detailed photoelectrochemical studies on these DS-PEC devices are discussed. PMID:25139154

  9. Specific of a photocurrent in GaN-based photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Marchenko, O. N.; Ermakov, I. A.; Puzyk, M. V.; Kovalev, D. S.; Ivanova, S. A.; Papchenko, B. P.; Usikov, A. S.; Chernyakov, A. E.

    2016-08-01

    An influence of various parameters of a photoelectrochemical cell (PECC) having a GaN working electrode on the photocurrent was studied. Type of the aqua electrolyte (alkaline (KOH)-, neutral salt (Na2SO4)- and acid (H2SO4)- based electrolytes) influences on transient time for the photocurrent stabilization. A transient time for the photo current stabilization was observed under illumination by the UV LED light sources. The shortest transient time and the highest photocurrent were observed in the alkaline-based electrolyte (∼0.5M KOH) with n- GaN working electrodes (ND-NA =(3-5)×1016 cm-3). PECC with electrolytes based on sodium sulfate and sulfuric acid demonstrated longer transient time (up to ten minutes) for the photocurrent stabilization and smaller photocurrent.

  10. Automatic illumination compensation device based on a photoelectrochemical biofuel cell driven by visible light.

    PubMed

    Yu, You; Han, Yanchao; Xu, Miao; Zhang, Lingling; Dong, Shaojun

    2016-04-28

    Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm(-2) and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications. PMID:27076202

  11. Automatic illumination compensation device based on a photoelectrochemical biofuel cell driven by visible light

    NASA Astrophysics Data System (ADS)

    Yu, You; Han, Yanchao; Xu, Miao; Zhang, Lingling; Dong, Shaojun

    2016-04-01

    Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm-2 and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications.Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm-2 and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00759g

  12. Photoelectrochemical based direct conversion systems

    SciTech Connect

    Kocha, S.; Arent, D.; Peterson, M.

    1995-09-01

    The goal of this research is to develop a stable, cost effective, photoelectrochemical based system that will split water upon illumination, producing hydrogen and oxygen directly, using sunlight as the only energy input. This type of direct conversion system combines a photovoltaic material and an electrolyzer into a single monolithic device. We report on our studies of two multifunction multiphoton photoelectrochemical devices, one based on the ternary semiconductor gallium indium phosphide, (GaInP{sub 2}), and the other one based on amorphous silicon carbide. We also report on our studies of the solid state surface treatment of GaInP{sub 2} as well as our continuing effort to develop synthetic techniques for the attachment of transition metal complexes to the surface of semiconductor electrodes. All our surface studies are directed at controlling the interface energetics and forming stable catalytic surfaces.

  13. Photoelectrochemical cells including chalcogenophosphate photoelectrodes

    NASA Technical Reports Server (NTRS)

    Reichman, B.; Byvik, C. E. (Inventor)

    1984-01-01

    Photoelectrochemical cells employing chalcogenophosphate (MPX3) photoelectrodes are described where M is selected from the group of transition metal series of elements beginning with scandium (atomic number 21) through germanium (atomic number 32) yttrium (atomic number 39) through antimony (atomic number 51) and lanthanum (atomic number 57) through polonium (atomic number 84); P is phosphorus; and X is selected from the chalogenide series consisting of sulfur, selenium, and tellurium. These compounds have bandgaps in the desirable range from 2.0 eV to 2.2 eV for the photoelectrolysis of water and are stable when used as photoelectrodes for the same.

  14. Photoelectrochemical cells - Conversion of intense optical energy

    NASA Technical Reports Server (NTRS)

    Wrighton, M. S.; Ellis, A. B.; Kaiser, S. W.

    1976-01-01

    Conversion of optical energy to chemical energy and/or electrical energy using wet photoelectrochemical cells is described. Emphasis is on (1) the photoelectrolysis of H2O to H2 and O2 using cells having n-type semiconductor photoelectrodes fabricated from TiO2, SnO2, SrTiO3, KTaO3, and KTa(0.77)Nb(0.23)O3, and (2) the conversion of light to electrical energy using CdSe- and CdS-based cells with polysulfide electrolytes.

  15. n-Type Si-based photoelectrochemical cell: New liquid junction photocell using a nonaqueous ferricenium/ferrocene electrolyte

    PubMed Central

    Legg, Kenneth D.; Ellis, Arthur B.; Bolts, Jeffrey M.; Wrighton, Mark S.

    1977-01-01

    n-Type Si has been shown to serve as a stable photoanode in a cell for the conversion of light to electricity. The other components of the cell are a Pt cathode and an electrolyte consisting of an ethanol solution of [n-Bu4N]ClO4 with a redox couple of ferricenium/ferrocene. Data from a two-compartment cell show that ferrocene is oxidized to ferricenium with 100 ± 2% current efficiency at the Si photoanode. Furthermore, prolonged irradiation of the Si in a one-compartment cell yields constant photocurrent and output characteristics. The maximum open-circuit photopotential is ∼700 mV, and the short-circuit quantum yield for electron flow at low light intensity exceeds 0.5. Conversion of monochromatic 632.8-nm light to electricity with ∼2% power efficiency at an output voltage of ∼200 mV has been sustained. These results represent a stable n-type Si-based photoelectrochemical cell. PMID:16592436

  16. Superlattice photoelectrodes for photoelectrochemical cells

    DOEpatents

    Nozik, Arthur J.

    1987-01-01

    A superlattice or multiple-quantum-well semiconductor is used as a photoelectrode in a photoelectrochemical process for converting solar energy into useful fuels or chemicals. The quantum minibands of the superlattice or multiple-quantum-well semiconductor effectively capture hot-charge carriers at or near their discrete quantum energies and deliver them to drive a chemical reaction in an electrolyte. The hot-charge carries can be injected into the electrolyte at or near the various discrete multiple energy levels quantum minibands, or they can be equilibrated among themselves to a hot-carrier pool and then injected into the electrolyte at one average energy that is higher than the lowest quantum band gap in the semiconductor.

  17. Photoelectrochemical investigation of a poly(ethylene oxide) cell

    SciTech Connect

    Sammells, A.F.; Ang, G.P.

    1984-03-01

    The photoelectrochemical properties of cells based on the solid polymer electrolyte (SPE) poly(ethylene oxide)/NaSCN with Na2S/S as a redox species are investigated experimentally. The preparation of the SPE is described in detail. Current/voltage curves or voltage/time are shown for cells using p-InP/SPE/conducting-glass, n-GaAs/SPE/conducting-glass, and p-InP/SPE/n-CdS structures. It is concluded that practical cells based on SPE of this type will require increases in the ionic conductivity of poly(ethylene oxide). 13 references.

  18. Increasing the open-circuit voltage of photoprotein-based photoelectrochemical cells by manipulation of the vacuum potential of the electrolytes.

    PubMed

    Tan, Swee Ching; Crouch, Lucy I; Mahajan, Sumeet; Jones, Michael R; Welland, Mark E

    2012-10-23

    The innately highly efficient light-powered separation of charge that underpins natural photosynthesis can be exploited for applications in photoelectrochemistry by coupling nanoscale protein photoreaction centers to man-made electrodes. Planar photoelectrochemical cells employing purple bacterial reaction centers have been constructed that produce a direct current under continuous illumination and an alternating current in response to discontinuous illumination. The present work explored the basis of the open-circuit voltage (V(OC)) produced by such cells with reaction center/antenna (RC-LH1) proteins as the photovoltaic component. It was established that an up to ~30-fold increase in V(OC) could be achieved by simple manipulation of the electrolyte connecting the protein to the counter electrode, with an approximately linear relationship being observed between the vacuum potential of the electrolyte and the resulting V(OC). We conclude that the V(OC) of such a cell is dependent on the potential difference between the electrolyte and the photo-oxidized bacteriochlorophylls in the reaction center. The steady-state short-circuit current (J(SC)) obtained under continuous illumination also varied with different electrolytes by a factor of ~6-fold. The findings demonstrate a simple way to boost the voltage output of such protein-based cells into the hundreds of millivolts range typical of dye-sensitized and polymer-blend solar cells, while maintaining or improving the J(SC). Possible strategies for further increasing the V(OC) of such protein-based photoelectrochemical cells through protein engineering are discussed.

  19. Triple junction polymer solar cells for photoelectrochemical water splitting.

    PubMed

    Esiner, Serkan; van Eersel, Harm; Wienk, Martijn M; Janssen, René A J

    2013-06-01

    A triple junction polymer solar cell in a novel 1 + 2 type configuration provides photoelectrochemical water splitting in its maximum power point at V ≈ 1.70 V with an estimated solar to hydrogen energy conversion efficiency of 3.1%. The triple junction cell consists of a wide bandgap front cell and two identical small bandgap middle and back cells.

  20. Integrated photoelectrochemical cell and system having a liquid electrolyte

    DOEpatents

    Deng, Xunming; Xu, Liwei

    2010-07-06

    An integrated photoelectrochemical (PEC) cell generates hydrogen and oxygen from water while being illuminated with radiation. The PEC cell employs a liquid electrolyte, a multi-junction photovoltaic electrode, and a thin ion-exchange membrane. A PEC system and a method of making such PEC cell and PEC system are also disclosed.

  1. Integrating a dual-silicon photoelectrochemical cell into a redox flow battery for unassisted photocharging.

    PubMed

    Liao, Shichao; Zong, Xu; Seger, Brian; Pedersen, Thomas; Yao, Tingting; Ding, Chunmei; Shi, Jingying; Chen, Jian; Li, Can

    2016-05-04

    Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient photoelectrochemical reactions. Here we report an efficient SRFC based on a dual-silicon photoelectrochemical cell and a quinone/bromine redox flow battery for in situ solar energy conversion and storage. Using narrow bandgap silicon for efficient photon collection and fast redox couples for rapid interface charge injection, our device shows an optimal solar-to-chemical conversion efficiency of ∼5.9% and an overall photon-chemical-electricity energy conversion efficiency of ∼3.2%, which, to our knowledge, outperforms previously reported SRFCs. The proposed SRFC can be self-photocharged to 0.8 V and delivers a discharge capacity of 730 mAh l(-1). Our work may guide future designs for highly efficient solar rechargeable devices.

  2. Photoelectrochemical cells based on hydrogen-atom abstraction and electron-transfer reactions in solution: systems based on benzophenone, 2-propanol, trialkylamines, and methyl viologen

    SciTech Connect

    Chandrasekaran, K.; Whitten, D.G.

    1981-12-02

    This paper reports the linking of well-studied solution photoprocesses such as hydrogen-atom abstraction by triplet benzophenone from 2-propanol and electron transfer from triethylamine to triplet benzophenone to proton reduction in aqueous acid via a two-compartment photoelectrochemical cell. In each case the intermediate reduction of N,N'-dimethyl-4,4'-bipyridinium (methyl viologen, MV/sup 2 +/) provides a means for circumventing undesirable radical reactions and generating a stable carrier in high overall efficiency. The net result is reasonably efficient generation of a photocurrent concurrent with the occurrence of an endothermic reaction providing products that can in principle be recycled. An interesting aspect of this work is the finding that the overall efficiency of these cells is enhanced by the photochemical self-sensitization of MV/sup +/ in the presence of 2-propanol or triethylamine and MV/sup 2 +/.

  3. Double junction photoelectrochemical solar cells based on Cu2ZnSnS4/Cu2ZnSnSe4 thin film as composite photocathode

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Qiang, Y. H.; Zhao, Y. L.; Gu, X. Q.

    2014-02-01

    A solvothermal method was used to synthesize Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) nanoparticles. CZTS/CZTSe bilayer films have been fabricated via a layer-by-layer blade coating process on the fluorine dope tin oxide (FTO) substrates. We converted conventional dye-sensitized solar cells (DSSCs) into double junction photoelectrochemical solar cells with the replacement of the Pt-coated counter electrode with the as-prepared films as composite photocathodes. Compared with conventional DSSCs, the cells show an increased short circuit current and power conversion efficiency.

  4. Photoelectrochemical based direct conversion systems for hydrogen production

    SciTech Connect

    Khaselev, O.; Bansal, A.; Kocha, S.; Turner, J.A.

    1998-08-01

    With an eye towards developing a photoelectrochemical system for hydrogen production using sunlight as the only energy input, two types of systems were studied, both involving multijunction devices. One set of cells consisted of a-Si triple junctions and the other a GaInP{sub 2}/GaAs tandem cell combination. Additional investigations were carried out on semiconductor surface modifications to move semiconductor band edges to more favorable energetic positions.

  5. The n-CdSe photoelectrochemical cell: wavelength-dependent photostability

    SciTech Connect

    Rubin, H.D.; Arent, D.J.; Bocarsly, A.B.

    1985-02-01

    Much recent work has focused on Fe(CN)/sub 6/ /SUP 4-/3-/ as a stabilizing electrolyte for n-CdX(X=S,Se) based photoelectrochemical cells (1-5). Prior studies performed in this laboratory (6) showed that irradiation of n-CdS in an electrolyte containing Fe(CN)/sub 6/ /SUP 4-/3-/ can lead to formation of a surface layer of (Cd /SUP II/ Fe /SUP II/III/ (CN)/sub 6/) /SUP 2-/1-/ . In the presence of the appropriate cations, this layer was associated with improved cell output parameters. These studies have now been extended to include the n-CdSe system. In this letter we wish to report an unprecedented wavelength dependence of the n-CdSe photoelectrochemical cell.

  6. Photoelectrochemical based direct conversion systems for hydrogen production

    SciTech Connect

    Kocha, S.; Peterson, M.; Arent, D.

    1996-10-01

    Photon driven, direct conversion systems consist of a light absorber and a water splitting catalyst as a monolithic system; water is split directly upon illumination. This one-step process eliminates the need to generate electricity externally and subsequently feed it to an electrolyzer. These configurations require only the piping necessary for transport of hydrogen to an external storage system or gas pipeline. This work is focused on multiphoton photoelectrochemical devices for production of hydrogen directly using sunlight and water. Two types of multijunction cells, one consisting of a-Si triple junctions and the other GaInP{sub 2}/GaAs homojunctions, were studied for the photoelectrochemical decomposition of water into hydrogen and oxygen from an aqueous electrolyte solution. To catalyze the water decomposition process, the illuminated surface of the device was modified either by addition of platinum colloids or by coating with ruthenium dioxide. These colloids have been characterized by gel electrophoresis.

  7. Visible light to electrical energy conversion using photoelectrochemical cells

    NASA Technical Reports Server (NTRS)

    Wrighton, Mark S. (Inventor); Ellis, Arthur B. (Inventor); Kaiser, Steven W. (Inventor)

    1983-01-01

    Sustained conversion of low energy visible or near i.r. light (>1.25 eV) to electrical energy has been obtained using wet photoelectrochemical cells where there are no net chemical changes in the system. Stabilization of n-type semi-conductor anodes of CdS, CdSe, CdTe, GaP, GaAs and InP to photoanodic dissolution is achieved by employing selected alkaline solutions of Na.sub.2 S, Na.sub.2 S/S, Na.sub.2 Se, Na.sub.2 Se/Se, Na.sub.2 Te and Na.sub.2 Te/Te as the electrolyte. The oxidation of (poly) sulfide, (poly)selenide or (poly)telluride species occurs at the irradiated anode, and reduction of polysulfide, polyselenide or polytelluride species occurs at the dark Pt cathode of the photoelectrochemical cell. Optical to electrical energy conversion efficiencies approaching 15% at selected frequencies have been observed in some cells. The wavelength for the onset of photocurrent corresponds to the band gap of the particular anode material used in the cell.

  8. Solar-rechargeable battery based on photoelectrochemical water oxidation: Solar water battery

    PubMed Central

    Kim, Gonu; Oh, Misol; Park, Yiseul

    2016-01-01

    As an alternative to the photoelectrochemical water splitting for use in the fuel cells used to generate electrical power, this study set out to develop a solar energy rechargeable battery system based on photoelectrochemical water oxidation. We refer to this design as a “solar water battery”. The solar water battery integrates a photoelectrochemical cell and battery into a single device. It uses a water oxidation reaction to simultaneously convert and store solar energy. With the solar water battery, light striking the photoelectrode causes the water to be photo-oxidized, thus charging the battery. During the discharge process, the solar water battery reduces oxygen to water with a high coulombic efficiency (>90%) and a high average output voltage (0.6 V). Because the reduction potential of oxygen is more positive [E0 (O2/H2O) = 1.23 V vs. NHE] than common catholytes (e.g., iodide, sulfur), a high discharge voltage is produced. The solar water battery also exhibits a superior storage ability, maintaining 99% of its specific discharge capacitance after 10 h of storage, without any evidence of self-discharge. The optimization of the cell design and configuration, taking the presence of oxygen in the cell into account, was critical to achieving an efficient photocharge/discharge. PMID:27629362

  9. Solar-rechargeable battery based on photoelectrochemical water oxidation: Solar water battery

    NASA Astrophysics Data System (ADS)

    Kim, Gonu; Oh, Misol; Park, Yiseul

    2016-09-01

    As an alternative to the photoelectrochemical water splitting for use in the fuel cells used to generate electrical power, this study set out to develop a solar energy rechargeable battery system based on photoelectrochemical water oxidation. We refer to this design as a “solar water battery”. The solar water battery integrates a photoelectrochemical cell and battery into a single device. It uses a water oxidation reaction to simultaneously convert and store solar energy. With the solar water battery, light striking the photoelectrode causes the water to be photo-oxidized, thus charging the battery. During the discharge process, the solar water battery reduces oxygen to water with a high coulombic efficiency (>90%) and a high average output voltage (0.6 V). Because the reduction potential of oxygen is more positive [E0 (O2/H2O) = 1.23 V vs. NHE] than common catholytes (e.g., iodide, sulfur), a high discharge voltage is produced. The solar water battery also exhibits a superior storage ability, maintaining 99% of its specific discharge capacitance after 10 h of storage, without any evidence of self-discharge. The optimization of the cell design and configuration, taking the presence of oxygen in the cell into account, was critical to achieving an efficient photocharge/discharge.

  10. Solar-rechargeable battery based on photoelectrochemical water oxidation: Solar water battery.

    PubMed

    Kim, Gonu; Oh, Misol; Park, Yiseul

    2016-01-01

    As an alternative to the photoelectrochemical water splitting for use in the fuel cells used to generate electrical power, this study set out to develop a solar energy rechargeable battery system based on photoelectrochemical water oxidation. We refer to this design as a "solar water battery". The solar water battery integrates a photoelectrochemical cell and battery into a single device. It uses a water oxidation reaction to simultaneously convert and store solar energy. With the solar water battery, light striking the photoelectrode causes the water to be photo-oxidized, thus charging the battery. During the discharge process, the solar water battery reduces oxygen to water with a high coulombic efficiency (>90%) and a high average output voltage (0.6 V). Because the reduction potential of oxygen is more positive [E(0) (O2/H2O) = 1.23 V vs. NHE] than common catholytes (e.g., iodide, sulfur), a high discharge voltage is produced. The solar water battery also exhibits a superior storage ability, maintaining 99% of its specific discharge capacitance after 10 h of storage, without any evidence of self-discharge. The optimization of the cell design and configuration, taking the presence of oxygen in the cell into account, was critical to achieving an efficient photocharge/discharge. PMID:27629362

  11. Solar-rechargeable battery based on photoelectrochemical water oxidation: Solar water battery.

    PubMed

    Kim, Gonu; Oh, Misol; Park, Yiseul

    2016-09-15

    As an alternative to the photoelectrochemical water splitting for use in the fuel cells used to generate electrical power, this study set out to develop a solar energy rechargeable battery system based on photoelectrochemical water oxidation. We refer to this design as a "solar water battery". The solar water battery integrates a photoelectrochemical cell and battery into a single device. It uses a water oxidation reaction to simultaneously convert and store solar energy. With the solar water battery, light striking the photoelectrode causes the water to be photo-oxidized, thus charging the battery. During the discharge process, the solar water battery reduces oxygen to water with a high coulombic efficiency (>90%) and a high average output voltage (0.6 V). Because the reduction potential of oxygen is more positive [E(0) (O2/H2O) = 1.23 V vs. NHE] than common catholytes (e.g., iodide, sulfur), a high discharge voltage is produced. The solar water battery also exhibits a superior storage ability, maintaining 99% of its specific discharge capacitance after 10 h of storage, without any evidence of self-discharge. The optimization of the cell design and configuration, taking the presence of oxygen in the cell into account, was critical to achieving an efficient photocharge/discharge.

  12. Integrating a dual-silicon photoelectrochemical cell into a redox flow battery for unassisted photocharging.

    PubMed

    Liao, Shichao; Zong, Xu; Seger, Brian; Pedersen, Thomas; Yao, Tingting; Ding, Chunmei; Shi, Jingying; Chen, Jian; Li, Can

    2016-01-01

    Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient photoelectrochemical reactions. Here we report an efficient SRFC based on a dual-silicon photoelectrochemical cell and a quinone/bromine redox flow battery for in situ solar energy conversion and storage. Using narrow bandgap silicon for efficient photon collection and fast redox couples for rapid interface charge injection, our device shows an optimal solar-to-chemical conversion efficiency of ∼5.9% and an overall photon-chemical-electricity energy conversion efficiency of ∼3.2%, which, to our knowledge, outperforms previously reported SRFCs. The proposed SRFC can be self-photocharged to 0.8 V and delivers a discharge capacity of 730 mAh l(-1). Our work may guide future designs for highly efficient solar rechargeable devices. PMID:27142885

  13. Integrating a dual-silicon photoelectrochemical cell into a redox flow battery for unassisted photocharging

    PubMed Central

    Liao, Shichao; Zong, Xu; Seger, Brian; Pedersen, Thomas; Yao, Tingting; Ding, Chunmei; Shi, Jingying; Chen, Jian; Li, Can

    2016-01-01

    Solar rechargeable flow cells (SRFCs) provide an attractive approach for in situ capture and storage of intermittent solar energy via photoelectrochemical regeneration of discharged redox species for electricity generation. However, overall SFRC performance is restricted by inefficient photoelectrochemical reactions. Here we report an efficient SRFC based on a dual-silicon photoelectrochemical cell and a quinone/bromine redox flow battery for in situ solar energy conversion and storage. Using narrow bandgap silicon for efficient photon collection and fast redox couples for rapid interface charge injection, our device shows an optimal solar-to-chemical conversion efficiency of ∼5.9% and an overall photon–chemical–electricity energy conversion efficiency of ∼3.2%, which, to our knowledge, outperforms previously reported SRFCs. The proposed SRFC can be self-photocharged to 0.8 V and delivers a discharge capacity of 730 mAh l−1. Our work may guide future designs for highly efficient solar rechargeable devices. PMID:27142885

  14. Photoelectrolysis of water at high current density - Use of laser light excitation of semiconductor-based photoelectrochemical cells

    NASA Technical Reports Server (NTRS)

    Wrighton, M. S.; Bocarsley, A. B.; Bolts, J. M.

    1978-01-01

    In the present paper, some results are given for UV laser light irradiation of the photoanode (SnO2, SrTiO3, or TiO2) in a cell for the light-driven electrolysis of H2O, at radiation intensities of up to 380 W/sq cm. The properties of the anode material are found to be independent of light intensity. Conversion of UV light to stored chemical energy in the form of 2H2/O2 from H2O was driven at a rate of up to 30 W/sq cm. High O2 evolution rates at the irradiated anodes without changes in the current-voltage curves are attributed to the excess oxidizing power associated with photogenerated holes. A test for this sort of hypothesis for H2 evolution at p-type materials is proposed.

  15. General Characterization Methods for Photoelectrochemical Cells for Solar Water Splitting.

    PubMed

    Shi, Xinjian; Cai, Lili; Ma, Ming; Zheng, Xiaolin; Park, Jong Hyeok

    2015-10-12

    Photoelectrochemical (PEC) water splitting is a very promising technology that converts water into clean hydrogen fuel and oxygen by using solar light. However, the characterization methods for PEC cells are diverse and a systematic introduction to characterization methods for PEC cells has rarely been attempted. Unlike most other review articles that focus mainly on the material used for the working electrodes of PEC cells, this review introduces general characterization methods for PEC cells, including their basic configurations and methods for characterizing their performance under various conditions, regardless of the materials used. Detailed experimental operation procedures with theoretical information are provided for each characterization method. The PEC research area is rapidly expanding and more researchers are beginning to devote themselves to related work. Therefore, the content of this Minireview can provide entry-level knowledge to beginners in the area of PEC, which might accelerate progress in this area.

  16. General Characterization Methods for Photoelectrochemical Cells for Solar Water Splitting.

    PubMed

    Shi, Xinjian; Cai, Lili; Ma, Ming; Zheng, Xiaolin; Park, Jong Hyeok

    2015-10-12

    Photoelectrochemical (PEC) water splitting is a very promising technology that converts water into clean hydrogen fuel and oxygen by using solar light. However, the characterization methods for PEC cells are diverse and a systematic introduction to characterization methods for PEC cells has rarely been attempted. Unlike most other review articles that focus mainly on the material used for the working electrodes of PEC cells, this review introduces general characterization methods for PEC cells, including their basic configurations and methods for characterizing their performance under various conditions, regardless of the materials used. Detailed experimental operation procedures with theoretical information are provided for each characterization method. The PEC research area is rapidly expanding and more researchers are beginning to devote themselves to related work. Therefore, the content of this Minireview can provide entry-level knowledge to beginners in the area of PEC, which might accelerate progress in this area. PMID:26365789

  17. Development of photoelectrochemical cells based on compound semiconductors and nonaqueous electrolytes. Semiannual report, May 1, 1981-October 31, 1981

    SciTech Connect

    Rauh, R. D.

    1982-03-01

    A reproducible procedure for chemical bath deposition (CBD) of CdSe has been documented in detail, allowing a consistent production of photoelectrode yielding 5.5 to 6.5% conversion efficiency in alkaline polysulfide electrolyte (employing a tungsten halogen lamp/KG-2 filter solar simulated light source). The CBD films of n-CdSe on Ti have achieved an efficiency of approx. 10% under both solar simulated and real sunlight conditions using an Fe(CN)/sub 6//sup -3///sup -4/ electrolyte at pH 13. For an initial current density of 16 mA/cm/sup 2/ (approx. 80 mW/cm/sup 2/ illumination), a decrease of approx. 25% is observed after 3 hours illumination. Research was completed on developing a stable Cu/sup +///sup +2/ redox electrolyte in CH/sub 3/CN, which contains excess Cl/sup -/, to promote photochemical stability. For poly-n-GaAs, best results were obtained for electrolytes containing approx. 0.5M Cucl, 0.05M CuCl/sub 2/, 1M tetrabutylammonium chloride, viz: at 80 mW/cm/sup 2/, j/sub sc/ = 19 mA/cm/sup 2/, V/sub oc/ = 0.74V, P/sub max/ = 3.78 mW/cm/sup 2/, ff = 0.27 and eta = 4.8% (eta = 8.1% at 8 mW/cm/sup 2/ irradiation). Five encapsulated sealed cells have been tested with 15 cm/sup 2/ photoelectrodes comprised of CBD CdSe on Ti. The cells are frontwall illuminated with various configurations for ion flow to the rear-placed Ni/CoS electrode. For one design, an efficiency of 4.3% was achieved under 63 mW/cm/sup 2/ real solar illumination. Laser spot scanning has been developed as a technique for evaluation of both large area geometrical effects and microscopic photoelectrode morphological effects on the performance of PECs.

  18. A Photoelectrochemical Solar Cell: An Undergraduate Experiment.

    ERIC Educational Resources Information Center

    Boudreau, Sharon M.; And Others

    1983-01-01

    Preparation and testing of a cadmium selenide photoelectrical solar cell was introduced into an environmental chemistry course to illustrate solid state semiconductor and electrochemical principles. Background information, procedures, and results are provided for the experiment which can be accomplished in a three- to four-hour laboratory session…

  19. Biological templates for antireflective current collectors for photoelectrochemical cell applications.

    PubMed

    Chiang, Chia-Ying; Epstein, Jillian; Brown, Adam; Munday, Jeremy N; Culver, James N; Ehrman, Sheryl

    2012-11-14

    Three-dimensional (3D) structures such as nanowires, nanotubes, and nanorods have the potential to increase surface area, reduce light reflection, and shorten charge carrier transport distances. The assembly of such structures thus holds great promise for enhancing photoelectrochemical solar cell efficiency. In this study, genetically modified Tobacco mosaic virus (TMV1cys) was used to form self-assembling 3D nanorod current collectors and low light-reflecting surfaces. Photoactive CuO was subsequently deposited by sputtering onto these patterned nanostructures, and these structures were examined for photocurrent activity. CuO thicknesses of 520 nm on TMV1cys patterned current collectors produced the highest photocurrent density of 3.15 mA/cm(2) yet reported for a similar sized CuO system. Reflectivity measurements are in agreement with full-wave electromagnetic simulations, which can be used as a design tool for optimizing the CuO system. Thus the combined effects of reducing charge carrier transport distance, increasing surface area, and the suppression of light reflection make these virus-templated surfaces ideal for photoelectrochemical applications.

  20. Iron Pyrite/Titanium Dioxide Photoanode for Extended Near Infrared Light Harvesting in a Photoelectrochemical Cell

    PubMed Central

    Wang, Di-Yan; Li, Cheng-Hung; Li, Shao-Sian; Kuo, Tsung-Rong; Tsai, Chin-Ming; Chen, Tin-Reui; Wang, Ying-Chiao; Chen, Chun-Wei; Chen, Chia-Chun

    2016-01-01

    The design of active and stable semiconducting composites with enhanced photoresponse from visible light to near infrared (NIR) is a key to improve solar energy harvesting for photolysis of water in photoelectrochemical cell. In this study, we prepared earth abundant semiconducting composites consisting of iron pyrite and Titanium oxide as a photoanode (FeS2/TiO2 photoanode) for photoelectrochemical applications. The detailed structure and atomic compositions of FeS2/TiO2 photoanode was characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), inductively coupled plasma with atomic emission spectroscopy (ICPAES) and Raman spectroscopy. Through the proper sulfurization treatment, the FeS2/TiO2 photoanode exhibited high photoresponse from visible light extended to near infrared range (900 nm) as well as stable durability test for 4 hours. We found that the critical factors to enhance the photoresponse are on the elimination of surface defect of FeS2 and on the enhancement of interface charge transfer between FeS2 and TiO2. Our overall results open a route for the design of sulfur-based binary compounds for photoelectrochemical applications. PMID:26852670

  1. Overall Photoelectrochemical Water Splitting using Tandem Cell under Simulated Sunlight.

    PubMed

    Kim, Jin Hyun; Kaneko, Hiroyuki; Minegishi, Tsutomu; Kubota, Jun; Domen, Kazunari; Lee, Jae Sung

    2016-01-01

    A stand-alone photoelectrochemical (PEC) water-splitting system driven only by sunlight was demonstrated with a tandem-scheme of Pt/CdS/CuGa3 Se5 /(Ag,Cu)GaSe2 photocathode and NiOOH/FeOOH/Mo:BiVO4 photoanode in a neutral phosphate buffer solution as an electrolyte. The as-prepared semi-transparent Mo:BiVO4 layer allows sunlight to pass through the top photoanode and reach the bottom photocathode. Consequently, the tandem cell showed stoichiometric hydrogen and oxygen evolution with a solar-to-hydrogen (STH) conversion efficiency of 0.67 % over 2 h without degradation. The stability and STH efficiency are the highest among similar configuration of PEC tandem cells.

  2. A Liquid Junction Photoelectrochemical Solar Cell Based on p-Type MeNH3PbI3 Perovskite with 1.05 V Open-Circuit Photovoltage.

    PubMed

    Hsu, Hsien-Yi; Ji, Li; Ahn, Hyun S; Zhao, Ji; Yu, Edward T; Bard, Allen J

    2015-11-25

    A liquid junction photoelectrochemical (PEC) solar cell based on p-type methylammonium lead iodide (p-MeNH3PbI3) perovskite with a large open-circuit voltage is developed. MeNH3PbI3 perovskite is readily soluble or decomposed in many common solvents. However, the solvent dichloromethane (CH2Cl2) can be employed to form stable liquid junctions. These were characterized with photoelectrochemical cells with several redox couples, including I3(-)/I(-), Fc/Fc(+), DMFc/DMFc(+), and BQ/BQ(•-) (where Fc is ferrocene, DMFc is decamethylferrocene, BQ is benzoquinone) in CH2Cl2. The solution-processed MeNH3PbI3 shows cathodic photocurrents and hence p-type behavior. The difference between the photocurrent onset potential and the standard potential for BQ/BQ(•-) is 1.25 V, which is especially large for a semiconductor with a band gap of 1.55 eV. A PEC photovoltaic cell, with a configuration of p-MeNH3PbI3/CH2Cl2, BQ (2 mM), BQ(•-) (2 mM)/carbon, shows an open-circuit photovoltage of 1.05 V and a short-circuit current density of 7.8 mA/cm(2) under 100 mW/cm(2) irradiation. The overall optical-to-electrical energy conversion efficiency is 6.1%. The PEC solar cell shows good stability for 5 h under irradiation.

  3. Electro-generated conducting polypyrrole polymers and applications in photoelectrochemical cells

    SciTech Connect

    Noufi, R.N.

    1983-01-01

    A major problem in the development of photoelectrochemical cells for solar energy conversion and storage is the susceptibility of small bandgap semiconductor materials to photodegradation. This problem could be overcome, in principle, by protecting the semiconductor electrode surface with electrically conducting polymer film. This film, acting as a barrier to ion/solvent transport, would inhibit photodegradation of the electrode surface while permitting electron exchange with the electrode. Recent studies on the electrogenerated polypyrrole and its applications in photoelectrochemical cells are presented.

  4. Wire Array Solar Cells: Fabrication and Photoelectrochemical Studies

    NASA Astrophysics Data System (ADS)

    Spurgeon, Joshua Michael

    Despite demand for clean energy to reduce our addiction to fossil fuels, the price of these technologies relative to oil and coal has prevented their widespread implementation. Solar energy has enormous potential as a carbon-free resource but is several times the cost of coal-produced electricity, largely because photovoltaics of practical efficiency require high-quality, pure semiconductor materials. To produce current in a planar junction solar cell, an electron or hole generated deep within the material must travel all the way to the junction without recombining. Radial junction, wire array solar cells, however, have the potential to decouple the directions of light absorption and charge-carrier collection so that a semiconductor with a minority-carrier diffusion length shorter than its absorption depth (i.e., a lower quality, potentially cheaper material) can effectively produce current. The axial dimension of the wires is long enough for sufficient optical absorption while the charge-carriers are collected along the shorter radial dimension in a massively parallel array. This thesis explores the wire array solar cell design by developing potentially low-cost fabrication methods and investigating the energy-conversion properties of the arrays in photoelectrochemical cells. The concept was initially investigated with Cd(Se, Te) rod arrays; however, Si was the primary focus of wire array research because its semiconductor properties make low-quality Si an ideal candidate for improvement in a radial geometry. Fabrication routes for Si wire arrays were explored, including the vapor-liquid-solid growth of wires using SiCl4. Uniform, vertically aligned Si wires were demonstrated in a process that permits control of the wire radius, length, and spacing. A technique was developed to transfer these wire arrays into a low-cost, flexible polymer film, and grow multiple subsequent arrays using a single Si(111) substrate. Photoelectrochemical measurements on Si wire array

  5. Enzyme-catalyzed biocathode in a photoelectrochemical biofuel cell

    NASA Astrophysics Data System (ADS)

    Yang, Jing; Hu, Donghua; Zhang, Xiaohuan; Wang, Kunqi; Wang, Bin; Sun, Bo; Qiu, Zhidong

    2014-12-01

    A novel double-enzyme photoelectrochemical biofuel cell (PEBFC) has been developed by taking glucose dehydrogenase (GDH) and horseradish peroxidase (HRP) as the enzyme of the photoanode and biocathode to catalyze the oxidation of glucose and the reduction of oxygen. A H2-mesoporphyrin IX is used as a dye for a TiO2 film electrode to fabricate a photoanode. The horseradish peroxidase (HRP) is immobilized on a glassy carbon (GC) electrode to construct a biocathode which is used to catalyze the reduction of oxygen in the PEBFC for the first time. The biocathode exhibits excellent electrocatalytic activity in the presence of O2. The performances of the PEBFC are obtained by current-voltage and power-voltage curves. The short-circuit current density (Isc), the open-circuit voltage (Voc), maximum power density (Pmax), fill factor (FF) and energy conversion efficiency (η) are 439 μA cm-2, 678 mV, 79 μW cm-2, 0.39 and 0.016%, respectively, and the incident photon-to-collected electron conversion efficiency (IPCE) is 32% at 350 nm. The Isc is higher than that of the PEBFC with Pt cathode, and the Voc is higher than that of the dye-sensitized solar cell or the enzyme-catalyzed biofuel cell operating individually, which demonstrates that the HRP is an efficient catalyst for the biocathode in the PEBFC.

  6. Polyoxymetalate liquid-catalyzed polyol fuel cell and the related photoelectrochemical reaction mechanism study

    NASA Astrophysics Data System (ADS)

    Wu, Weibing; Liu, Wei; Mu, Wei; Deng, Yulin

    2016-06-01

    A novel design of liquid catalyzed fuel cell (LCFC), which uses polyoxometalates (POMs) as the photocatalyst and charge carrier has been reported previously. In this paper, the adaptability of biomass fuels (e.g., glycerol and glucose) to the LCFC and corresponding cell performance were studied in detail here. An interesting finding that greatly differs from conventional fuel cell is that high molecular weight fuels rather than small molecule fuels (e.g., methanol and ethylene glycol) are favored by the novel LCFC with respect to the power densities. The power output of LCFC strongly depends on the number and structure of hydroxyl groups in the biomass fuels. The evidence of UV-Vis and 1H NMR spectra shows that the preassociation between POM and alcohol fuels, which determines the photoelectrochemical reaction pathway of POM, is enhanced as the number of hydroxyl increases. Experimental results also demonstrate that more hydroxyl groups in the molecules lead to faster photoelectrochemical reaction between POM and fuels, higher reduction degree of POM, and further higher power output of LCFC. Our study reveals that biomass-based polyhydroxyl compounds such as starch, hemicellulose and cellulose are potential high-performance fuels for LCFC.

  7. Hollow TiO₂ porous nanosheets: transformation from ZnO porous nanosheets and application in photoelectrochemical cells.

    PubMed

    Chen, Haining; Zhu, Liqun; Hou, Qin; Liu, Huicong; Li, Weiping

    2013-06-01

    Changing the sheets: Hollow TiO₂ porous nanosheets (HTPNs) are prepared on ITO glass through an improved TiO₂ polycrystalline shell-assisted cation exchange by using ZnO porous nanosheets (grown by using indirect electrodeposition) as a template. Quantum dot-sensitized solar cells based on HTPNs exhibit a high performance, and other photoelectrochemical devices are expected to be prepared based on HTPNs.

  8. ZnO nanorod arrays for photoelectrochemical cells.

    PubMed

    Yu, Qiang; Cao, Chuanbao

    2012-05-01

    The splitting of water using photoelectrochemical (PEC) cells to produce hydrogen is one of the most sustainable forms of energy production and more and more 1-D nanostructrues semiconductors used as photoelectrodes have been studied extensively. However, it is not clear whether the photoconversion efficiencies of such nanostructure devices are limited by the architectures of the 1-D electrodes. Here, we explore the effect of the architecture like the length and width of ZnO nanorods on the PEC cells performance for the first time. The as-prepared nanorods have diameters of 40-50 nm and lengths of 400-800 nm. Preliminary measurements exhibit that the resulting electrodes have promising PEC properties. Mott-Schottky measurements give a flat-band potential of +0.10 V, a carrier density of 3.7 x 10(17) cm(-3), and a space-charge layer of 26 nm. The photocurrent of 800 nm-long nanorods shows 10 times higher than that of 400 nm-long ones, and an encouraging maximum photoconversion efficiency of 0.25% is obtained under illumination of 100 mW/cm2 (AM 1.5), which is among the highest reported for an undoped ZnO photoelectrode to date.

  9. Combined biomass valorization and hydrogen production in a photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Cha, Hyun Gil; Choi, Kyoung-Shin

    2015-04-01

    In a typical hydrogen-producing photoelectrochemical cell (PEC), water reduction at the cathode (producing hydrogen) is accompanied by water oxidation at the anode (producing oxygen). This anode reaction is, however, not kinetically favourable. Here we investigate the possibility of utilizing solar energy for biomass conversion by performing the oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA) at the anode of a PEC. HMF is a key intermediate in biomass conversion, and FDCA is an important monomer for the production of numerous polymers. Using 2,2,6,6-tetramethylpiperidine-1-oxyl as a mediator, we obtained a near-quantitative yield and 100% Faradaic efficiency at ambient conditions without the use of precious-metal catalysts. This reaction is also thermodynamically and kinetically more favourable than water oxidation. Our results suggest that solar-driven biomass conversion can be a viable anode reaction that has the potential to increase both the efficiency and the utility of PECs constructed for solar-fuel production.

  10. Photoelectrochemical cell using dye sensitized zinc oxide nanowires grown on carbon fibers

    NASA Astrophysics Data System (ADS)

    Unalan, Husnu Emrah; Wei, Di; Suzuki, Kenichi; Dalal, Sharvari; Hiralal, Pritesh; Matsumoto, Hidetoshi; Imaizumi, Shinji; Minagawa, Mie; Tanioka, Akihiko; Flewitt, Andrew J.; Milne, William I.; Amaratunga, Gehan A. J.

    2008-09-01

    Zinc oxide (ZnO) nanowires (NWs) grown on carbon fibers using a vapor transport and condensation approach are used as the cathode of a photoelectrochemical cell. The carbon fibers were obtained by electrospray deposition and take the form of a flexible carbon fabric. The ZnO NW on carbon fiber anode is combined with a "black dye" photoabsorber, an electrolyte, and a platinum (Pt) counterelectrode to complete the cell. The results show that ZnO NW and carbon fibers can be used for photoinduced charge separation/charge transport and current collection, respectively, in a photoelectrochemical cell.

  11. Photoelectrochemical Properties of Nanocrystalline Sb6O13, MgSb2O6, and ZnSb2O6-Based Electrodes for Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Jang, Jiyeon; Kim, Seung-Joo

    2012-10-01

    Three kinds of antimony compounds - Sb6O13, MgSb2O6 and ZnSb2O6 - were prepared in the form of nanocrystalline film and their photo-electrochemical properties were investigated. The preparation of Sb6O13 was based on thermolysis of a colloidal Sb2O5·4H2O suspension. MgSb2O6 and ZnSb2O6 were prepared via low-temperature hydrothermal methods. All the compounds exhibited semiconducting properties applicable to dye-sensitized solar cell (DSSC). The energy band gaps were estimated to be 3.39 eV for Sb6O13, 3.60 eV for MgSb2O6, and 3.31 eV for ZnSb2O6, respectively. After sensitization with a conventional ruthenium-dye (N719), Sb6O13-based solar cell exhibited the highest open circuit voltage (Voc = 0.76 V) whereas the Voc values (0.44-0.46 V) of MgSb2O6 and ZnSb2O6 are relatively low. The Voc values were proven to be related to the flat band potentials of the antimony compounds. The overall solar-to-electric energy conversion efficiencies were in the range of 0.7-1.0% under AM 1.5, 100 mW/cm2 illumination.

  12. Atomic Layer Deposited Corrosion Protection: A Path to Stable and Efficient Photoelectrochemical Cells.

    PubMed

    Scheuermann, Andrew G; McIntyre, Paul C

    2016-07-21

    A fundamental challenge in developing photoelectrochemical cells for the renewable production of solar chemicals and fuels is the simultaneous requirement of efficient light absorption and robust stability under corrosive conditions. Schemes for corrosion protection of semiconductor photoelectrodes such as silicon using deposited layers were proposed and attempted for several decades, but increased operational lifetimes were either insufficient or the resulting penalties for device efficiency were prohibitive. In recent years, advances in atomic layer deposition (ALD) of thin coatings have made novel materials engineering possible, leading to substantial and simultaneous improvements in stability and efficiency of photoelectrochemical cells. The self-limiting, layer-by-layer growth of ALD makes thin films with low pinhole densities possible and may also provide a path to defect control that can generalize this protection technology to a large set of materials necessary to fully realize photoelectrochemical cell technology for artificial photosynthesis.

  13. Atomic Layer Deposited Corrosion Protection: A Path to Stable and Efficient Photoelectrochemical Cells.

    PubMed

    Scheuermann, Andrew G; McIntyre, Paul C

    2016-07-21

    A fundamental challenge in developing photoelectrochemical cells for the renewable production of solar chemicals and fuels is the simultaneous requirement of efficient light absorption and robust stability under corrosive conditions. Schemes for corrosion protection of semiconductor photoelectrodes such as silicon using deposited layers were proposed and attempted for several decades, but increased operational lifetimes were either insufficient or the resulting penalties for device efficiency were prohibitive. In recent years, advances in atomic layer deposition (ALD) of thin coatings have made novel materials engineering possible, leading to substantial and simultaneous improvements in stability and efficiency of photoelectrochemical cells. The self-limiting, layer-by-layer growth of ALD makes thin films with low pinhole densities possible and may also provide a path to defect control that can generalize this protection technology to a large set of materials necessary to fully realize photoelectrochemical cell technology for artificial photosynthesis. PMID:27359352

  14. Photoelectrochemical investigation of ultrathin film iron oxide solar cells prepared by atomic layer deposition.

    SciTech Connect

    Klahr, B. M.; Martinson, A. B. F.; Hamann, T. W.

    2011-01-01

    Atomic layer deposition was used to grow conformal thin films of hematite with controlled thickness on transparent conductive oxide substrates. The hematite films were incorporated as photoelectrodes in regenerative photoelectrochemical cells employing an aqueous [Fe(CN){sub 6}]{sup 3-/4-} electrolyte. Steady state current density versus applied potential measurements under monochromatic and simulated solar illumination were used to probe the photoelectrochemical properties of the hematite electrodes as a function of film thickness. Combining the photoelectrochemical results with careful optical measurements allowed us to determine an optimal thickness for a hematite electrode of {approx}20 nm. Mott-Schottky analysis of differential capacitance measurements indicated a depletion region of {approx}17 nm. Thus, only charge carriers generated in the depletion region were found to contribute to the photocurrent.

  15. Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

    PubMed Central

    Swierk, John R.; Méndez-Hernández, Dalvin D.; McCool, Nicholas S.; Liddell, Paul; Terazono, Yuichi; Pahk, Ian; Tomlin, John J.; Oster, Nolan V.; Moore, Thomas A.; Moore, Ana L.; Gust, Devens; Mallouk, Thomas E.

    2015-01-01

    Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ > 590 nm) illumination in a dye-sensitized TiO2 solar cell. We report the synthesis, spectral, and electrochemical properties of the sensitizers. Despite slow recombination of photoinjected electrons with oxidized porphyrins, photocurrents are low because of low injection yields and slow electron self-exchange between oxidized porphyrins. The free-base porphyrins are stable under conditions of water photoelectrolysis and in some cases photovoltages in excess of 1 V are observed. PMID:25583488

  16. Low-toxic Ag2S quantum dots for photoelectrochemical detection glucose and cancer cells.

    PubMed

    Zhang, Xiaoru; Liu, Mingshuai; Liu, Hongxia; Zhang, Shusheng

    2014-06-15

    A new photoelectrochemical (PEC) biosensor was developed using low-toxic Ag2S QDs as photoelectrochemically active species. Energy levels of Ag2S and Ag2Se QD were compared to explain their differences in the PEC performance. The preparation condition of Ag2S QD was optimized and its structure characterization was measured. Then the developed photoelectric active interface was used to detect glucose and MCF-7 cancer cell and showed the good sensitivity and specificity. Under optimal condition, detection limits of 3.2 × 10(-5)M for glucose and 98 cells/mL for MCF-7 cell were achieved. Thus, the prepared Ag2S QD could serve as an excellent and promising photoelectric active material in the PEC biosensor.

  17. Assembling Supramolecular Dye-Sensitized Photoelectrochemical Cells for Water Splitting.

    PubMed

    Ding, Xin; Gao, Yan; Ye, Lu; Zhang, Linlin; Sun, Licheng

    2015-12-01

    The method used to assemble dye-sensitized photoelectrochemical (DS-PEC) devices plays a vital role in determining its photoactivity and stability. We report a simple and effective method to assemble supramolecular DS-PECs introducing PMMA as support material and a catalyst modified with long carbon chains as photoanodes. The long carbon chains in combination with PMMA allow to better immobilize the catalyst. DS-PECs obtained by this simple method have display excellent photoactivities and stabilities. A photocurrent density of 1.1 mA cm(-2) and a maximum IPCE of 9.5 % have been obtained with a 0.2 V vs NHE external bias.

  18. Fluorescent gold nanoclusters based photoelectrochemical sensors for detection of H2O2 and glucose.

    PubMed

    Zhang, Jianxiu; Tu, Liping; Zhao, Shuang; Liu, Guohua; Wang, Yangyun; Wang, Yong; Yue, Zhao

    2015-05-15

    In this work, low-toxicity fluorescent gold nanoclusters (AuNCs) based photoelectrochemical sensors were developed for H2O2 and glucose detection. Herein, the processes used to fabricate the sensors and the photoelectrochemical performances of the sensors under different conditions were presented. Based on the energy band levels of the AuNCs and electron tunneling processes, a detailed photoelectrochemical sensing model was given. The designed sensors were then used for H2O2 and glucose detection without any extra modification of the AuNCs or complex enzyme immobilization. The results demonstrate that the AuNCs allow for H2O2 sensing based on their capacity for both fluorescence and catalysis. Indeed, it was observed that H2O2 was catalyzed by the AuNCs and reduced by photoinduced electrons derived from excited AuNCs. Furthermore, an enhancement in photocurrent amplitude followed the increase in the concentrations of H2O2 and glucose. The effects of the types of ligands surrounding the AuNCs and the applied potential on the output photocurrent were well studied to optimize the measurement conditions. The sensitivity and LOD of MUA-AuNCs at -500 mV were 4.33 nA/mM and 35 μM, respectively. All experimental results indicated that AuNCs could not only serve as a promising photoelectrical material for building the photoelectrochemical biosensors but as catalysts for H2O2 sensing.

  19. High-efficiency, thin-film, cadmium chalocogenide photoelectrochemical cell with in situ storage

    NASA Astrophysics Data System (ADS)

    Manassen, J.; Licht, S.; Hodes, G.; Cahen, D.; Lev, M.

    1986-04-01

    A photoelectrochemical cell with in situ storage, based on a Cd(Se,Te) photoelectrode in a polysulfide solution, was constructed. The counter-electrode was cobalt sulfide on brass and the membrane Permion 1010. A reproducible plating method, suitable for a 20-cm area, was developed, giving a maximum power of 200 mA. Photoetching, criticality important, was done in concentrated hydrochloric acid under reverse bias. The polarization behavior of the large CoS counterelectrodes was studied; the presently used geometry of a frontwall cell gives a polarization loss of about 10%. The water transport through two kinds of membranes was found to depend on the cation in solution. Greater water transport was found with potassium ion than with sodium ion in the electrolyte. A technical version of the cell with in situ storage was produced with the membrane in cylindrical form. Its lower resistance improved the difference between day and night current. After working two months under real weather conditions, the photoelectrode deteriorated to half its initial output. The chemistry of polysulfide solutions was studied, revealing compositions providing maximum stability and efficiency.

  20. Photoelectrochemical cell having photoanode with thin boron phosphide coating as a corrosion resistant layer

    DOEpatents

    Baughman, Richard J.; Ginley, David S.

    1984-01-01

    A surface prone to corrosion in corrosive environments is rendered anticorrosive by CVD growing a thin continuous film, e.g., having no detectable pinholes, thereon, of boron phosphide. In one embodiment, the film is semiconductive. In another aspect, the invention is an improved photoanode, and/or photoelectrochemical cell with a photoanode having a thin film of boron phosphide thereon rendering it anitcorrosive, and providing it with unexpectedly improved photoresponsive properties.

  1. Development of photoelectrochemical cells based on compound semiconductors and nonaqueous electrolyes. Quarterly technical progress report, August 1, 1980-October 31, 1980

    SciTech Connect

    Rauh, R.D.

    1980-12-01

    A solar cell using polyvinylpyrrolidone treated polycrystalline n-GaAs and CH/sub 3/CN, I/sub 3//sup -//I/sup -/ electrolyte achieved a power conversion efficiency of 4.3% with i/sub sc/ = 11.6 mA/cm/sup 2/, V/sub oc/ = -0.485V, P/sub max/ = 2.3 mW/cm/sup 2/, ff = 0.40 at 53.3 mW/cm/sup 2/ Xe arc intensity. A p-GaAs electrode in the same acetonitrile electrolyte gives photovoltages similar to those reported for aqueous HI/I/sub 2/ electrolyte, but the photocurrent decays rapidly with time. Exploratory work on p-Zn/sub 3/P/sub 2/ indicates that nonaqueous electrolytes will probably be required for EPCs based on this semiconductor due to a dark reaction of Zn/sub 3/P/sub 2/ with H/sub 2/O to liberate PH/sub 3/. Stable photoresponse was obtained in CH/sub 3/CN, I/sub 3//sup -//I/sup -/. Optimum thickness of electrodeposited CdSe films on titanium substrates was determined to be >3..mu... Anodization and dipping in ZnCl/sub 2/ solution improves i/sub sc/ and V/sub oc/, respectively, to give electrodes capable of >4% efficiency in aqueous polysulfide at 67 mW/cm/sup 2/ tungsten-iodine lamp intensity. Prototype solar cells of 4 cm/sup 2/ area suffer a reduction in efficiency due to iR drop between the electrodes and counter electrode polarization. The former may be reduced by perforating the photoelectrode. Photoaction spectra of electrodeposited CdSe films have been obtained with a newly constructed apparatus for recording source-corrected photocurrent action spectra of semiconductor electrodes.

  2. Tuning Interfacial Electron Transfer in Nanostructured Cuprous Oxide Photoelectrochemical Cells with Charge-Selective Molecular Coatings.

    PubMed

    Haynes, Keith M; Kratch, Kaci C; Stovall, Sean D; Obondi, Christopher O; Thurber, Casey R; Youngblood, W Justin

    2015-08-01

    The coating of nanostructured films of cuprous oxide with electroactive molecules strongly affects their photoelectrochemical performance in nonaqueous photocells, with photocurrent density increased up to an order of magnitude relative to bare cuprous oxide films or almost completely suppressed, depending on the choice of molecular adsorbant. Among adsorbants that enhance photocurrent, a strong variance of photoelectrochemical behavior is observed with changes in the molecular structure of the sensitizer, associated with differences in the reorganization energy and molecular size, which are interpreted to enhance forward electron transport and impede electrolyte/photocathode recombination, respectively. These results demonstrate that nanostructured cuprous oxide is a promising cathode material for p-type dye-sensitized solar cells. PMID:26075573

  3. Bulk heterojunction photoelectrochemical cells consisting of oxotitanyl phthalocyanine nanoporous films and I(3)(-)/I(-) redox couple.

    PubMed

    Hoshino, Katsuyoshi; Hirasawa, Yusuke; Kim, Sang-Kook; Saji, Tetsuo; Katano, Jun-Ichi

    2006-11-23

    Photoelectrochemical cells based on oxotitanylphthalocyanine (TiOPc) films and an I(3)(-)/I(-) redox couple have been constructed. The TiOPc films were prepared on an indium-tin oxide coated glass plate (ITO) by the micellar disruption method and characterized by their unique nanoporous structure. A photocurrent action spectrum for input radiation directed through the ITO/TiOPc film, film-thickness dependence, and morphological investigation revealed that the cells consisted of a bulk heterojunction formed between the nanoporous TiOPc films and the liquid I3-/I- electrolyte, resulting in a larger short-circuit current (J(sc)= 2.1 mA/cm(2)), open-circuit voltage (V(oc)= 0.11 V), fill factor (ff= 0.31), and hence a larger energy conversion efficiency (eta= 0.13% for an incident white-light intensity of 53 mW/cm2) than the bilayer structure composed of the vaccum-evaporated TiOPc compact film and the I(3)(-)/I(-) electrolyte (J(sc)= 0.16 mA/cm(2), V(oc)= 0.018 V, ff = 0.27, and eta = (1.5 x 10(-3)%).

  4. Nanostructured photoelectrochemical solar cell for nitrogen reduction using plasmon-enhanced black silicon.

    PubMed

    Ali, Muataz; Zhou, Fengling; Chen, Kun; Kotzur, Christopher; Xiao, Changlong; Bourgeois, Laure; Zhang, Xinyi; MacFarlane, Douglas R

    2016-04-20

    Ammonia (NH3) is one of the most widely produced chemicals worldwide. It has application in the production of many important chemicals, particularly fertilizers. It is also, potentially, an important energy storage intermediate and clean energy carrier. Ammonia production, however, mostly uses fossil fuels and currently accounts for more than 1.6% of global CO2 emissions (0.57  Gt in 2015). Here we describe a solar-driven nanostructured photoelectrochemical cell based on plasmon-enhanced black silicon for the conversion of atmospheric N2 to ammonia producing yields of 13.3 mg m(-2) h(-1) under 2 suns illumination. The yield increases with pressure; the highest observed in this work was 60 mg m(-2) h(-1) at 7 atm. In the presence of sulfite as a reactant, the process also offers a direct solar energy route to ammonium sulfate, a fertilizer of economic importance. Although the yields are currently not sufficient for practical application, there is much scope for improvement in the active materials in this cell.

  5. Nanostructured photoelectrochemical solar cell for nitrogen reduction using plasmon-enhanced black silicon.

    PubMed

    Ali, Muataz; Zhou, Fengling; Chen, Kun; Kotzur, Christopher; Xiao, Changlong; Bourgeois, Laure; Zhang, Xinyi; MacFarlane, Douglas R

    2016-01-01

    Ammonia (NH3) is one of the most widely produced chemicals worldwide. It has application in the production of many important chemicals, particularly fertilizers. It is also, potentially, an important energy storage intermediate and clean energy carrier. Ammonia production, however, mostly uses fossil fuels and currently accounts for more than 1.6% of global CO2 emissions (0.57  Gt in 2015). Here we describe a solar-driven nanostructured photoelectrochemical cell based on plasmon-enhanced black silicon for the conversion of atmospheric N2 to ammonia producing yields of 13.3 mg m(-2) h(-1) under 2 suns illumination. The yield increases with pressure; the highest observed in this work was 60 mg m(-2) h(-1) at 7 atm. In the presence of sulfite as a reactant, the process also offers a direct solar energy route to ammonium sulfate, a fertilizer of economic importance. Although the yields are currently not sufficient for practical application, there is much scope for improvement in the active materials in this cell. PMID:27093916

  6. Nanostructured photoelectrochemical solar cell for nitrogen reduction using plasmon-enhanced black silicon

    PubMed Central

    Ali, Muataz; Zhou, Fengling; Chen, Kun; Kotzur, Christopher; Xiao, Changlong; Bourgeois, Laure; Zhang, Xinyi; MacFarlane, Douglas R.

    2016-01-01

    Ammonia (NH3) is one of the most widely produced chemicals worldwide. It has application in the production of many important chemicals, particularly fertilizers. It is also, potentially, an important energy storage intermediate and clean energy carrier. Ammonia production, however, mostly uses fossil fuels and currently accounts for more than 1.6% of global CO2 emissions (0.57  Gt in 2015). Here we describe a solar-driven nanostructured photoelectrochemical cell based on plasmon-enhanced black silicon for the conversion of atmospheric N2 to ammonia producing yields of 13.3 mg m−2 h−1 under 2 suns illumination. The yield increases with pressure; the highest observed in this work was 60 mg m−2 h−1 at 7 atm. In the presence of sulfite as a reactant, the process also offers a direct solar energy route to ammonium sulfate, a fertilizer of economic importance. Although the yields are currently not sufficient for practical application, there is much scope for improvement in the active materials in this cell. PMID:27093916

  7. A thin-film polycrystalline photoelectrochemical cell with 8% solar conversion efficiency

    NASA Astrophysics Data System (ADS)

    Hodes, G.

    1980-05-01

    A thin-film polycrystalline CdSe(0.65)Te(0.35)/polysulfide-based photoelectrochemical solar cell with an energy conversion efficiency of up to 8% is presented. Cell electrodes were prepared by painting a slurry of sintered CdSe(0.65)Te(0.35) powder onto a Ti substrate and then annealing in an inert atmosphere and etching by various means. Solar efficiencies of the electrodes immersed in an aqueous electrolyte 1 M in KOH, Na2S and S with a counter electrode of sulfide brass gauze of up to 5% were obtained following a HCl:HNO3 etch, up to 5.5% following etching in dilute aqueous CrO3 and up to 8.0% following photoetching and K2CrO4 treatment. The spectral response of the anode in polysulfide solution exhibits a short-wavelength cutoff due to electrolyte absorption, a flat plateau region, and a fairly sharp long-wavelength cut-off indicating an effective band gap of about 1.45 eV, similar to that of CdTe. Output stability has been found to decrease with increasing output current, remaining stable for more than 21 h at a current of 20 mA/sq cm.

  8. Nanostructured photoelectrochemical solar cell for nitrogen reduction using plasmon-enhanced black silicon

    NASA Astrophysics Data System (ADS)

    Ali, Muataz; Zhou, Fengling; Chen, Kun; Kotzur, Christopher; Xiao, Changlong; Bourgeois, Laure; Zhang, Xinyi; Macfarlane, Douglas R.

    2016-04-01

    Ammonia (NH3) is one of the most widely produced chemicals worldwide. It has application in the production of many important chemicals, particularly fertilizers. It is also, potentially, an important energy storage intermediate and clean energy carrier. Ammonia production, however, mostly uses fossil fuels and currently accounts for more than 1.6% of global CO2 emissions (0.57 Gt in 2015). Here we describe a solar-driven nanostructured photoelectrochemical cell based on plasmon-enhanced black silicon for the conversion of atmospheric N2 to ammonia producing yields of 13.3 mg m-2 h-1 under 2 suns illumination. The yield increases with pressure; the highest observed in this work was 60 mg m-2 h-1 at 7 atm. In the presence of sulfite as a reactant, the process also offers a direct solar energy route to ammonium sulfate, a fertilizer of economic importance. Although the yields are currently not sufficient for practical application, there is much scope for improvement in the active materials in this cell.

  9. Multielectrode photoelectrochemical cell for unassisted photocatalysis and photosynthesis

    SciTech Connect

    Smotkin, E.; Bard, A.J.; Fox, M.A.

    1988-12-27

    A multielectrode photoelectrochemical unit for unassisted photoelectrical-induction of a chemical reaction is described comprising: a housing having at least one light-passing side, a first end, a second end and a housing wall defining an internal section; a first photoactive bipolar electrode panel in the internal section having a semiconductor side, an ohmic contact layer and a underside; a second photoactive bipolar electrode panel in the internal section, the second photoactive bipolar electrode panel having a semiconductor side, an ohmic contact layer and a catalytic side and being attached to the housing wall near the second end of the internal section with the catalytic side oriented toward the second end and partially forming a second terminal compartment, an internal compartment in the internal section being partially formed by the underside of the first photoactive bipolar electrode panel and the semiconductor side of the second photoactive bipolar electrode panel, the first and second photoactive bipolar electrode panels being attached to the housing walls to prevent liquid flow between the internal compartment and the terminal compartments and being positioned so that light from an external source entering the internal section is substantially incident upon the semi-conductor sides.

  10. Realizing InGaN monolithic solar-photoelectrochemical cells for artificial photosynthesis

    SciTech Connect

    Dahal, R.; Pantha, B. N.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2014-04-07

    InGaN alloys are very promising for solar water splitting because they have direct bandgaps that cover almost the whole solar spectrum. The demonstration of direct solar-to-fuel conversion without external bias with the sunlight being the only energy input would pave the way for realizing photoelectrochemical (PEC) production of hydrogen by using InGaN. A monolithic solar-PEC cell based on InGaN/GaN multiple quantum wells capable to directly generate hydrogen gas under zero bias via solar water splitting is reported. Under the irradiation by a simulated sunlight (1-sun with 100 mW/cm{sup 2}), a 1.5% solar-to-fuel conversion efficiency has been achieved under zero bias, setting a fresh benchmark of employing III-nitrides for artificial photosynthesis. Time dependent hydrogen gas production photocurrent measured over a prolonged period (measured for 7 days) revealed an excellent chemical stability of InGaN in aqueous solution of hydrobromic acid. The results provide insights into the architecture design of using InGaN for artificial photosynthesis to provide usable clean fuel (hydrogen gas) with the sunlight being the only energy input.

  11. Converting environmentally hazardous materials into clean energy using a novel nanostructured photoelectrochemical fuel cell

    SciTech Connect

    Gan, Yong X.; Gan, Bo J.; Clark, Evan; Su, Lusheng; Zhang, Lihua

    2012-09-15

    Highlights: ► A photoelectrochemical fuel cell has been made from TiO{sub 2} nanotubes. ► The fuel cell decomposes environmentally hazardous materials to produce electricity. ► Doping the anode with a transition metal oxide increases the visible light sensitivity. ► Loading the anode with a conducting polymer enhances the visible light absorption. -- Abstract: In this work, a novel photoelectrochemical fuel cell consisting of a titanium dioxide nanotube array photosensitive anode and a platinum cathode was made for decomposing environmentally hazardous materials to produce electricity and clean fuel. Titanium dioxide nanotubes (TiO{sub 2} NTs) were prepared via electrochemical oxidation of pure Ti in an ammonium fluoride and glycerol-containing solution. Scanning electron microscopy was used to analyze the morphology of the nanotubes. The average diameter, wall thickness and length of the as-prepared TiO{sub 2} NTs were determined. The photosensitive anode made from the highly ordered TiO{sub 2} NTs has good photo-catalytic property, as proven by the decomposition tests on urea, ammonia, sodium sulfide and automobile engine coolant under ultraviolet (UV) radiation. To improve the efficiency of the fuel cell, doping the TiO{sub 2} NTs with a transition metal oxide, NiO, was performed and the photosensitivity of the doped anode was tested under visible light irradiation. It is found that the NiO-doped anode is sensitive to visible light. Also found is that polyaniline-doped photosensitive anode can harvest photon energy in the visible light spectrum range much more efficiently than the NiO-doped one. It is concluded that the nanostructured photoelectrochemical fuel cell can generate electricity and clean fuel by decomposing hazardous materials under sunlight.

  12. Tin doped indium oxide core—TiO2 shell nanowires on stainless steel mesh for flexible photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Hong Noh, Jun; Ding, Bo; Soo Han, Hyun; Seong Kim, Ju; Hoon Park, Jong; Baek Park, Sang; Suk Jung, Hyun; Lee, Jung-Kun; Sun Hong, Kug

    2012-02-01

    Photoanode architecture is built on highly conductive tin doped indium oxide (ITO) nanowires (NWs) on a flexible stainless steel mesh (SSM). ITO nanowires were coated with the atomic layer deposition grown TiO2 layer and the photoelectrochemical performance of the stainless steel mesh based photoanode were examined as a function of wire-length and shell-thickness. The photoanode consisting of 20 μm-long nanowire core and 36 nm thick shell increased the photocurrent of the testing cell by 4 times, compared to a reference cell. This enhanced photochemical activity is attributed to higher light harvesting efficiency of nanowire arrays and suppressed charge recombination of core-shell structure.

  13. A Simple Photoelectrochemical Cell Using Fe+++/Fe++(aq) As Redox Couple

    NASA Astrophysics Data System (ADS)

    Saxena, Vibha; Koiry, S. P.; Veerender, P.; Vasundhara, Aswal, D. K.; Gupta, S. K.; Shivran, Neelam; Mula, S.; Chattopadhyay, S.; Yakhmi, J. V.

    2010-12-01

    We report a simple photoelectrochemical cell (PEC) using a derivative of borondipyrromethane (BODIPY), that is, (4,4-difluoro-1,3,5,7,8-pentamethyl-2,6-diethyl-4-bora-3a,4a-diaza-s-indecene) as dye sensitizer and an aqueous electrolyte containing Ferric/ferrous redox couple (F+++/Fe++). Under white light illumination of intensity ˜1 mW/cm2, the open circuit voltage and short-circuit current of the PEC was found to be respectively, 180 mV and 1.3 μA/cm2.

  14. Photoelectrochemical and Electrochemical Characterization of Sub-Micro-Gram Amounts of Organic Semiconductors Using Scanning Droplet Cell Microscopy

    PubMed Central

    2014-01-01

    A model organic semiconductor (MDMO-PPV) was used for testing a modified version of a photoelectrochemical scanning droplet cell microscope (PE-SDCM) adapted for use with nonaqueous electrolytes and containing an optical fiber for localized illumination. The most attractive features of the PE-SDCM are represented by the possibility of addressing small areas on the investigated substrate and the need of small amounts of electrolyte. A very small amount (ng) of the material under study is sufficient for a complete electrochemical and photoelectrochemical characterization due to the scanning capability of the cell. The electrochemical behavior of the polymer was studied in detail using potentiostatic and potentiodynamic investigations as well as electrochemical impedance spectroscopy. Additionally, the photoelectrochemical properties were investigated under illumination conditions, and the photocurrents found were at least 3 orders of magnitude higher than the dark (background) current, revealing the usefulness of this compact microcell for photovoltaic characterizations. PMID:25101149

  15. CdS/MoS2 heterojunction-based photoelectrochemical DNA biosensor via enhanced chemiluminescence excitation.

    PubMed

    Zang, Yang; Lei, Jianping; Hao, Qing; Ju, Huangxian

    2016-03-15

    This work developed a CdS/MoS2 heterojunction-based photoelectrochemical biosensor for sensitive detection of DNA under the enhanced chemiluminescence excitation of luminol catalyzed by hemin-DNA complex. The CdS/MoS2 photocathode was prepared by the stepwise assembly of MoS2 and CdS quantum dots (QDs) on indium tin oxide (ITO), and achieved about 280% increasing of photocurrent compared to pure CdS QDs electrode due to the formation of heterostructure. High photoconversion efficiency in the photoelectrochemical system was identified to be the rapid spatial charge separation of electron-hole pairs by the extension of electron transport time and electron lifetime. In the presence of target DNA, the catalytic hairpin assembly was triggered, and simultaneously the dual hemin-labeled DNA probe was introduced to capture DNA/CdS/MoS2 modified ITO electrode. Thus the chemiluminescence emission of luminol was enhanced via hemin-induced mimetic catalysis, leading to the physical light-free photoelectrochemical strategy. Under optimized conditions, the resulting photoelectrode was proportional to the logarithm of target DNA concentration in the range from 1 fM to 100 pM with a detection limit of 0.39 fM. Moreover, the cascade amplification biosensor demonstrated high selectivity, desirable stability and good reproducibility, showing great prospect in molecular diagnosis and bioanalysis.

  16. Experimenting with Photoelectrochemical Cells in Drinking Straws: Practical Aids for Learning about Solar Energy in School or at Home

    ERIC Educational Resources Information Center

    Appleyard, S. J.

    2008-01-01

    Photoelectrochemical cells using dye-sensitized ZnO with a Cu[superscript 2+]/Fe[superscript 2+]/Fe[superscript 3+] electrolyte can be easily made at home or in a school classroom with household chemicals and other readily available materials. The cells, which are made with wire housed within plastic drinking straws, have open-circuit voltages of…

  17. A novel photoelectrochemical biosensor for protein kinase activity assay based on phosphorylated graphite-like carbon nitride.

    PubMed

    Li, Xue; Zhou, Yunlei; Xu, Yan; Xu, Huijie; Wang, Minghui; Yin, Huanshun; Ai, Shiyun

    2016-08-31

    Protein kinases are general and significant regulators in the cell signaling pathway, and it is still greatly desired to achieve simple and quick kinase detection. Herein, we develop a simple and sensitive photoelectrochemical strategy for the detection of protein kinase activity based on the bond between phosphorylated peptide and phosphorylated graphite-like carbon nitride (P-g-C3N4) conjugates triggered by Zr(4+) ion coordination. Under optimal conditions, the increased photocurrent is proportional to the protein kinase A (PKA) concentration ranging from 0.05 to 50 U/mL with a detection limit of 0.077 U/mL. Moreover, this photoelectrochemical assay can be also applied to quantitative analysis of kinase inhibition. The results indicated that the IC50 value (inhibitor concentration producing 50% inhibitor) for ellagic acid was 9.1 μM. Moreover, the developed method is further applied to detect PKA activity in real samples, which contains serum from healthy person and gastric cancer patients and breast tissue from healthy person and breast cancer patients. Therefore, the established protocol provides a new and simple tool for assay of kinase activity and its inhibitors with low cost and high sensitivity. PMID:27506341

  18. A novel photoelectrochemical biosensor for protein kinase activity assay based on phosphorylated graphite-like carbon nitride.

    PubMed

    Li, Xue; Zhou, Yunlei; Xu, Yan; Xu, Huijie; Wang, Minghui; Yin, Huanshun; Ai, Shiyun

    2016-08-31

    Protein kinases are general and significant regulators in the cell signaling pathway, and it is still greatly desired to achieve simple and quick kinase detection. Herein, we develop a simple and sensitive photoelectrochemical strategy for the detection of protein kinase activity based on the bond between phosphorylated peptide and phosphorylated graphite-like carbon nitride (P-g-C3N4) conjugates triggered by Zr(4+) ion coordination. Under optimal conditions, the increased photocurrent is proportional to the protein kinase A (PKA) concentration ranging from 0.05 to 50 U/mL with a detection limit of 0.077 U/mL. Moreover, this photoelectrochemical assay can be also applied to quantitative analysis of kinase inhibition. The results indicated that the IC50 value (inhibitor concentration producing 50% inhibitor) for ellagic acid was 9.1 μM. Moreover, the developed method is further applied to detect PKA activity in real samples, which contains serum from healthy person and gastric cancer patients and breast tissue from healthy person and breast cancer patients. Therefore, the established protocol provides a new and simple tool for assay of kinase activity and its inhibitors with low cost and high sensitivity.

  19. Solar water splitting in a molecular photoelectrochemical cell

    PubMed Central

    Alibabaei, Leila; Brennaman, M. Kyle; Norris, Michael R.; Kalanyan, Berç; Song, Wenjing; Losego, Mark D.; Concepcion, Javier J.; Binstead, Robert A.; Parsons, Gregory N.; Meyer, Thomas J.

    2013-01-01

    Artificial photosynthesis and the production of solar fuels could be a key element in a future renewable energy economy providing a solution to the energy storage problem in solar energy conversion. We describe a hybrid strategy for solar water splitting based on a dye sensitized photoelectrosynthesis cell. It uses a derivatized, core–shell nanostructured photoanode with the core a high surface area conductive metal oxide film––indium tin oxide or antimony tin oxide––coated with a thin outer shell of TiO2 formed by atomic layer deposition. A “chromophore–catalyst assembly” 1, [(PO3H2)2bpy)2Ru(4-Mebpy-4-bimpy)Rub(tpy)(OH2)]4+, which combines both light absorber and water oxidation catalyst in a single molecule, was attached to the TiO2 shell. Visible photolysis of the resulting core–shell assembly structure with a Pt cathode resulted in water splitting into hydrogen and oxygen with an absorbed photon conversion efficiency of 4.4% at peak photocurrent. PMID:24277806

  20. Nonplasmonic Hot-Electron Photocurrents from Mn-Doped Quantum Dots in Photoelectrochemical Cells.

    PubMed

    Dong, Yitong; Rossi, Daniel; Parobek, David; Son, Dong Hee

    2016-03-01

    We report the measurement of the hot-electron current in a photoelectrochemical cell constructed from a glass/ITO/Al2 O3 (ITO=indium tin oxide) electrode coated with Mn-doped quantum dots, where hot electrons with a large excess kinetic energy were produced through upconversion of the excitons into hot electron hole pairs under photoexcitation at 3 eV. In our recent study (J. Am. Chem. Soc. 2015, 137, 5549), we demonstrated the generation of hot electrons in Mn-doped II-VI semiconductor quantum dots and their usefulness in photocatalytic H2 production reaction, taking advantage of the more efficient charge transfer of hot electrons compared with band-edge electrons. Here, we show that hot electrons produced in Mn-doped CdS/ZnS quantum dots possess sufficient kinetic energy to overcome the energy barrier from a 5.4-7.5 nm thick Al2 O3 layer producing a hot-electron current in photoelectrochemical cell. This work demonstrates the possibility of harvesting hot electrons not only at the interface of the doped quantum dot surface, but also far away from it, thus taking advantage of the capability of hot electrons for long-range electron transfer across a thick energy barrier.

  1. Spatially Separated Photosystem II and a Silicon Photoelectrochemical Cell for Overall Water Splitting: A Natural-Artificial Photosynthetic Hybrid.

    PubMed

    Wang, Wangyin; Wang, Hong; Zhu, Qingjun; Qin, Wei; Han, Guangye; Shen, Jian-Ren; Zong, Xu; Li, Can

    2016-08-01

    Integrating natural and artificial photosynthetic platforms is an important approach to developing solar-driven hybrid systems with exceptional function over the individual components. A natural-artificial photosynthetic hybrid platform is formed by wiring photosystem II (PSII) and a platinum-decorated silicon photoelectrochemical (PEC) cell in a tandem manner based on a photocatalytic-PEC Z-scheme design. Although the individual components cannot achieve overall water splitting, the hybrid platform demonstrated the capability of unassisted solar-driven overall water splitting. Moreover, H2 and O2 evolution can be separated in this system, which is ascribed to the functionality afforded by the unconventional Z-scheme design. Furthermore, the tandem configuration and the spatial separation between PSII and artificial components provide more opportunities to develop efficient natural-artificial hybrid photosynthesis systems. PMID:27345863

  2. Spatially Separated Photosystem II and a Silicon Photoelectrochemical Cell for Overall Water Splitting: A Natural-Artificial Photosynthetic Hybrid.

    PubMed

    Wang, Wangyin; Wang, Hong; Zhu, Qingjun; Qin, Wei; Han, Guangye; Shen, Jian-Ren; Zong, Xu; Li, Can

    2016-08-01

    Integrating natural and artificial photosynthetic platforms is an important approach to developing solar-driven hybrid systems with exceptional function over the individual components. A natural-artificial photosynthetic hybrid platform is formed by wiring photosystem II (PSII) and a platinum-decorated silicon photoelectrochemical (PEC) cell in a tandem manner based on a photocatalytic-PEC Z-scheme design. Although the individual components cannot achieve overall water splitting, the hybrid platform demonstrated the capability of unassisted solar-driven overall water splitting. Moreover, H2 and O2 evolution can be separated in this system, which is ascribed to the functionality afforded by the unconventional Z-scheme design. Furthermore, the tandem configuration and the spatial separation between PSII and artificial components provide more opportunities to develop efficient natural-artificial hybrid photosynthesis systems.

  3. Electrochemical, Electrochemiluminescence, and Photoelectrochemical Aptamer-Based Nanostructured Sensors for Biomarker Analysis

    PubMed Central

    Ravalli, Andrea; Voccia, Diego; Palchetti, Ilaria; Marrazza, Giovanna

    2016-01-01

    Aptamer-based sensors have been intensively investigated as potential analytical tools in clinical analysis providing the desired portability, fast response, sensitivity, and specificity, in addition to lower cost and simplicity versus conventional methods. The aim of this review, without pretending to be exhaustive, is to give the readers an overview of recent important achievements about electrochemical, electrochemiluminescence, and photoelectrochemical aptasensors for the protein biomarker determination, mainly cancer related biomarkers, by selected recent publications. Special emphasis is placed on nanostructured-based aptasensors, which show a substantial improvement of the analytical performances. PMID:27490578

  4. Electrochemical, Electrochemiluminescence, and Photoelectrochemical Aptamer-Based Nanostructured Sensors for Biomarker Analysis.

    PubMed

    Ravalli, Andrea; Voccia, Diego; Palchetti, Ilaria; Marrazza, Giovanna

    2016-08-02

    Aptamer-based sensors have been intensively investigated as potential analytical tools in clinical analysis providing the desired portability, fast response, sensitivity, and specificity, in addition to lower cost and simplicity versus conventional methods. The aim of this review, without pretending to be exhaustive, is to give the readers an overview of recent important achievements about electrochemical, electrochemiluminescence, and photoelectrochemical aptasensors for the protein biomarker determination, mainly cancer related biomarkers, by selected recent publications. Special emphasis is placed on nanostructured-based aptasensors, which show a substantial improvement of the analytical performances.

  5. Electrolyte Concentration Effect of a Photoelectrochemical Cell Consisting of TiO 2 Nanotube Anode

    DOE PAGES

    Ren, Kai; Gan, Yong X.; Nikolaidis, Efstratios; Sofyani, Sharaf Al; Zhang, Lihua

    2013-01-01

    The photoelectrochemical responses of a TiO 2 nanotube anode in ethylene glycol (EG), glycerol, ammonia, ethanol, urea, and Na 2 S electrolytes with different concentrations were investigated. The TiO 2 nanotube anode was highly efficient in photoelectrocatalysis in these solutions under UV light illumination. The photocurrent density is obviously affected by the concentration change. Na 2 S generated the highest photocurrent density at 0, 1, and 2 V bias voltages, but its concentration does not significantly affect the photocurrent density. Urea shows high open circuit voltage at proper concentration and low photocurrent at different concentrations. Externally applied bias voltage ismore » also an important factor that changes the photoelectrochemical reaction process. In view of the open circuit voltage, EG, ammonia, and ethanol fuel cells show the trend that the open circuit voltage (OCV) increases with the increase of the concentration of the solutions. Glycerol has the highest OCV compared with others, and it deceases with the increase in the concentration because of the high viscosity. The OCV of the urea and Na 2 S solutions did not show obvious concentration effect.« less

  6. Use of amorphous silicon tandem junction solar cells for hydrogen production in a photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Stavrides, Alex; Kunrath, Augusto; Hu, Jian; Treglio, Richard; Feldman, Ari; Marsen, Bjorn; Cole, Brian; Miller, Eric; Madan, Arun

    2006-08-01

    We report the use of amorphous silicon (a-Si) tandem junctions as part of an integral "hybrid" photoelectrochemical (PEC) cell to produce hydrogen directly from water using sunlight. The device configuration consists of stainless steel (SS)/ni IIpni Ip/ZnO/WO 3. When the device is immersed in an electrolyte and illuminated, O II is evolved at the WO 3/electrolyte interface and H II is produced at the counter electrode. A voltage >1.23V is required to split water; typically 1.6-1.8V are needed, taking account of losses in a practical water-splitting system. We use a-Si tandem cells, deposited by plasma-enhanced chemical vapor deposition, to supply this voltage. Current matching in the two a-Si subcells is achieved by altering the thicknesses of the two layers (i I and i II) while keeping their band gaps at ~1.75eV, which results in a device with an open circuit voltage >1.6V, short circuit current density (J sc) >6mA/cm2 (on SS substrates), and a fill factor >0.6. Deposition on a textured SnO II coated glass has resulted in J sc >9mA/cm2. Photoactive WO 3 films, deposited using the RF sputtering technique, have achieved photocurrents >3mA/cm2 at 1.6V vs. saturated calomel electrode (SCE). The PEC device operates at the point at which the WO 3 photocurrent IV curve and the a-Si (filtered by WO 3) light IV curve cross, leading to operating currents of 2.5mA/cm2 and solar-to-hydrogen (STH) conversion efficiency of >3%.

  7. Electrochemical and photoelectrochemical nano-immunesensing using origami paper based method.

    PubMed

    Hasanzadeh, Mohammad; Shadjou, Nasrin

    2016-04-01

    Patterned paper has characteristics that lead to miniaturized assays that run by capillary action with small volumes of fluids. These methods suggest a path for the development of simple, inexpensive, and portable diagnostic assays that can be useful in remote settings, where simple immunoassays are becoming increasingly important for detecting disease and monitoring health. Incorporation of nanomaterials plays a major role in sensing probe immobilization and detection sensitivity of paper-based devices. Nanomaterial properties, such as increased surface area, have aided with signal amplification and lower detection limits. This review focuses on application of nanomaterials as signal amplification elements on origami paper-based electro-analytical devices for immune biomarkers detection with a brief introduction about various fabrication techniques and designs, biological and detection methods. In this review, we comprehensively summarize the selected latest research articles from 2013 to May 2015 on application of nanomaterials in various types of origami paper based electrochemical and photoelectrochemical immunosensors. The review breaks into two parts. The first part devotes to the development and applications of nanomaterials in electrochemical immunesensing. The second part provides an overview of recent origami paper based photoelectrochemical immunosensors.

  8. Electrochemical and photoelectrochemical nano-immunesensing using origami paper based method.

    PubMed

    Hasanzadeh, Mohammad; Shadjou, Nasrin

    2016-04-01

    Patterned paper has characteristics that lead to miniaturized assays that run by capillary action with small volumes of fluids. These methods suggest a path for the development of simple, inexpensive, and portable diagnostic assays that can be useful in remote settings, where simple immunoassays are becoming increasingly important for detecting disease and monitoring health. Incorporation of nanomaterials plays a major role in sensing probe immobilization and detection sensitivity of paper-based devices. Nanomaterial properties, such as increased surface area, have aided with signal amplification and lower detection limits. This review focuses on application of nanomaterials as signal amplification elements on origami paper-based electro-analytical devices for immune biomarkers detection with a brief introduction about various fabrication techniques and designs, biological and detection methods. In this review, we comprehensively summarize the selected latest research articles from 2013 to May 2015 on application of nanomaterials in various types of origami paper based electrochemical and photoelectrochemical immunosensors. The review breaks into two parts. The first part devotes to the development and applications of nanomaterials in electrochemical immunesensing. The second part provides an overview of recent origami paper based photoelectrochemical immunosensors. PMID:26838927

  9. Stable n-CuInSe/sub 2/iodide-iodine photoelectrochemical cell

    DOEpatents

    Cahen, D.; Chen, Y.W.

    1984-09-20

    In a photoelectrochemical solar cell, stable output and solar efficiency in excess of 10% are achieved with a photoanode of n-CuInSe/sub 2/ electrode material and an iodine/iodide redox couple used in a liquid electrolyte. The photoanode is prepared by treating the electrode material by chemical etching, for example in Br/sub 2//MeOH; heating the etched electrode material in air or oxygen; depositing a surface film coating of indium on the electrode material after the initial heating; and thereafter again heating the electrode material in air or oxygen to oxidize the indium. The electrolyte is treated by the addition of Cu/sup +/ or Cu/sup 2 +/ salts and in In/sup 3 +/ salts.

  10. Stable N-CuInSe.sub.2 /iodide-iodine photoelectrochemical cell

    DOEpatents

    Cahen, David; Chen, Yih W.

    1985-01-01

    In a photoelectrochemical solar cell, stable output and solar efficiency in excess of 10% are achieved with a photoanode of n-CuInSe.sub.2 electrode material and an iodine/iodide redox couple used in a liquid electrolyte. The photoanode is prepared by treating the electrode material by chemical etching, for example in Br.sub.2 /MeOH; heating the etched electrode material in air or oxygen; depositing a surface film coating of indium on the electrode material after the initial heating; and thereafter again heating the electrode material in air or oxygen to oxidize the indium. The electrolyte is treated by the addition of Cu.sup.+ or Cu.sup.2+ salts and In.sup.3+ salts.

  11. Bio-Photoelectrochemical Solar Cells Incorporating Reaction Center and Reaction Center Plus Light Harvesting Complexes

    NASA Astrophysics Data System (ADS)

    Yaghoubi, Houman

    Harvesting solar energy can potentially be a promising solution to the energy crisis now and in the future. However, material and processing costs continue to be the most important limitations for the commercial devices. A key solution to these problems might lie within the development of bio-hybrid solar cells that seeks to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. The bio-photoelectrochemical cell technologies exploit biomimetic means of energy conversion by utilizing plant-derived photosystems which can be inexpensive and ultimately the most sustainable alternative. Plants and photosynthetic bacteria harvest light, through special proteins called reaction centers (RCs), with high efficiency and convert it into electrochemical energy. In theory, photosynthetic RCs can be used in a device to harvest solar energy and generate 1.1 V open circuit voltage and ~1 mA cm-2 short circuit photocurrent. Considering the nearly perfect quantum yield of photo-induced charge separation, efficiency of a protein-based solar cell might exceed 20%. In practice, the efficiency of fabricated devices has been limited mainly due to the challenges in the electron transfer between the protein complex and the device electrodes as well as limited light absorption. The overarching goal of this work is to increase the power conversion efficiency in protein-based solar cells by addressing those issues (i.e. electron transfer and light absorption). This work presents several approaches to increase the charge transfer rate between the photosynthetic RC and underlying electrode as well as increasing the light absorption to eventually enhance the external quantum efficiency (EQE) of bio-hybrid solar cells. The first approach is to decrease the electron transfer distance between one of the redox active sites in the RC and the underlying electrode by direct attachment of the of protein complex

  12. Polytypic Nanocrystals of Cu-Based Ternary Chalcogenides: Colloidal Synthesis and Photoelectrochemical Properties.

    PubMed

    Wu, Liang; Chen, Shi-You; Fan, Feng-Jia; Zhuang, Tao-Tao; Dai, Chen-Min; Yu, Shu-Hong

    2016-05-01

    Heterocrystalline polytype nanostructured semiconductors have been attracting more and more attention in recent years due to their novel structures and special interfaces. Up to now, controlled polytypic nanostructures are mostly realized in II-VI and III-V semiconductors. Herein, we report the synthesis and photoelectrochemical properties of Cu-based ternary I-III-VI2 chalcogenide polytypic nanocrystals, with a focus on polytypic CuInS2 (CIS), CuInSe2 (CISe), and CuIn(S0.5Se0.5)2 alloy nanocrystals. Each obtained polytypic nanocrystal is constructed with a wurtzite hexagonal column and a zinc blende/chalcopyrite cusp, regardless of the S/Se ratio. The growth mechanisms of polytypic CIS and CISe nanocrystals have been studied by time-dependent experiments. The polytypic nanocrystals are solution-deposited on indium-tin oxide glass substrate and used as a photoelectrode, thus showing stable photoelectrochemical activity in aqueous solution. Density functional theory calculation was used to study the electronic structure and the band gap alignment. This versatile synthetic method provides a new route for synthesis of novel polytypic nanostructured semiconductors with unique properties. PMID:27063512

  13. Bismuth sulfide nanoflakes and nanorods as high performance photodetectors and photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Chao, Junfeng; Xing, Shumin; Zhao, Yanchun; Gao, Suling; Song, Qinghua; Guo, Lixia; Wang, Di; Zhang, Tingliang

    2016-11-01

    Flake-like and rod-like bismuth sulfide nanostructures were synthesized via a facile polyol refluxing process. The rigid photodetectors based on both nanomaterials have the features of linear photocurrent characteristics and good sensitivity. Especially, the rigid bismuth sulfide nanoflakes photodetector has fast response time of 0.5 s and recovery time of 0.7 s. The flexible photodetectors were then fabricated on PET substrate, and this caused both the response time and the recovery time to increase by a factor of ∼2.5. Moreover, the photoelectrochemical (PEC) devices exhibited photosensitivity with the features of rapid response and recovery time, high on/off ratio and stable switching cycle performance. Our results imply that the two types of bismuth sulfide nanomaterials are prospective candidates for next generation photodetectors and optoelectronic switches.

  14. Silicon microhole arrays architecture for stable and efficient photoelectrochemical cells using ionic liquids electrolytes

    NASA Astrophysics Data System (ADS)

    Shen, Xiaojuan; Chen, Ling; Li, Junnan; Zhao, Jie

    2016-06-01

    Silicon microhole arrays (SiMHs) structure is constructed and fabricated by a low-cost maskless anodic etching process, which is applied as the photoanode for the silicon photoelectrochemical (PEC) cells. The depths of silicon microhole arrays can be independently controlled by the etching time. The light-scattering properties are also investigated. Additionally, surface morphology analysis show that large hole diameters of SiMHs is very favourable for the full-filling of ionic liquids electrolyte. Therefore, better electrochemical contact as well as high ionic conductivity of the ionic liquids electrolyte renders the PEC SiMHs solar cells to exhibit more excellent performance. After optimization, the maximum PCE could be achieved at 4.04% for the SiMHs cell. The performance of the SiMHs cell is highly comparable to that of silicon nanowires cell. More importantly, the liquid-state electrolyte is confined in the unique microhole structure, which can obviously prevent the leakage of the ionic liquids electrolyte, resulting in much better long-term stability than the reference devices. These preliminary results validate the concept of interpenetrating networks with semiconductor structure/ILs junction to develop stable and efficient PEC cells.

  15. Directed assembly of the thylakoid membrane on nanostructured TiO2 for a photo-electrochemical cell

    NASA Astrophysics Data System (ADS)

    Kavadiya, Shalinee; Chadha, Tandeep S.; Liu, Haijun; Shah, Vivek B.; Blankenship, Robert E.; Biswas, Pratim

    2016-01-01

    The thylakoid membrane mainly consists of photosystem I (PSI), photosystem II (PSII) and the cytochrome b6f embedded in a lipid bilayer. PSI and PSII have the ability to capture sunlight and create an electron-hole pair. The study aims at utilizing these properties by using the thylakoid membrane to construct a photo-electrochemical cell. A controlled aerosol technique, electrohydrodynamic atomization, allows a systematic study by the fabrication of different cell configurations based on the surfactant concentration without any linker, sacrificial electron donor and mediator. The maximum photocurrent density observed is 6.7 mA cm-2 under UV and visible light, and 12 μA cm-2 under visible light illumination. The electron transfer occurs from PSII to PSI via cytochrome b6f and the electron at PSII is regenerated by water oxidation, similar to the z-scheme of photosynthesis. This work shows that re-engineering the natural photosynthesis circuit by the novel technique of electrospray deposition can result in an environmentally friendly method of harvesting sunlight.The thylakoid membrane mainly consists of photosystem I (PSI), photosystem II (PSII) and the cytochrome b6f embedded in a lipid bilayer. PSI and PSII have the ability to capture sunlight and create an electron-hole pair. The study aims at utilizing these properties by using the thylakoid membrane to construct a photo-electrochemical cell. A controlled aerosol technique, electrohydrodynamic atomization, allows a systematic study by the fabrication of different cell configurations based on the surfactant concentration without any linker, sacrificial electron donor and mediator. The maximum photocurrent density observed is 6.7 mA cm-2 under UV and visible light, and 12 μA cm-2 under visible light illumination. The electron transfer occurs from PSII to PSI via cytochrome b6f and the electron at PSII is regenerated by water oxidation, similar to the z-scheme of photosynthesis. This work shows that re

  16. A miniature photoelectrochemical sensor based on organic electrochemical transistor for sensitive determination of chemical oxygen demand in wastewaters.

    PubMed

    Liao, Jianjun; Lin, Shiwei; Zeng, Min; Yang, Yue

    2016-05-01

    A three-electrode configuration is often required in the conventional photoelectrochemical measurements. Nevertheless, one common drawback is the reference electrode and the counter electrode used in the measurements, which has been proved to be an impediment for the miniaturization. In this study, a simple, cost-effective and miniature photoelectrochemical sensor based on high sensitive organic electrochemical transistor (OECT) is developed and used for the determination of chemical oxygen demand (COD) in wastewaters. The devices show detection limit down to 0.01 mg/L COD, which is two orders of magnitude better than that of the conventional photoelectrochemical method. The excellent sensing performance can be contributed to the novel sensing mechanism of OECT devices. That is, the devices are sensitive to the potential changes induced by the photoelectrochemical reaction on TiO2 nanotube arrays gate electrodes. Real sample analyses are also carried out. The results demonstrate that the measured COD values using the OECT devices and the standard dichromate methods are in a good agreement. Since the proposed sensor is constructed on a miniature transistor, it is expected that the device shows a promising application on the integrated COD monitoring platform.

  17. Photoelectrochemical corrosion of GaN-based p-n structures

    NASA Astrophysics Data System (ADS)

    Fomichev, A. D.; Kurin, S. Yu; Ermakovi, I. A.; Puzyk, M. V.; Usikov, A. S.; Helava, H.; Nikiforov, A.; Papchenko, B. P.; Makarov, Yu N.; Chernyakov, A. E.

    2016-08-01

    Direct water photoelectrolysis using III-N materials is a promising way for hydrogen production. GaN/AlGaN based p-n structures were used in a photoelectrochemical process to investigate the material etching (corrosion) in an electrolyte. At the beginning, the corrosion performs through the top p-type layers via channels associated with threading defects and can penetrate deep into the structure. Then, the corrosion process occurs in lateral direction in n- type layers forming voids and cavities in the structure. The lateral etching is due to net positive charges at the AlGaN/GaN interfaces arising because of spontaneous and piezoelectric polarization in the structure and positively charged ionized donors in the space charge region of the p-n junction.

  18. Modeling practical performance limits of photoelectrochemical water splitting based on the current state of materials research.

    PubMed

    Seitz, Linsey C; Chen, Zhebo; Forman, Arnold J; Pinaud, Blaise A; Benck, Jesse D; Jaramillo, Thomas F

    2014-05-01

    Photoelectrochemical (PEC) water splitting is a means to store solar energy in the form of hydrogen. Knowledge of practical limits for this process can help researchers assess their technology and guide future directions. We develop a model to quantify loss mechanisms in PEC water splitting based on the current state of materials research and calculate maximum solar-to-hydrogen (STH) conversion efficiencies along with associated optimal absorber band gaps. Various absorber configurations are modeled considering the major loss mechanisms in PEC devices. Quantitative sensitivity analyses for each loss mechanism and each absorber configuration show a profound impact of both on the resulting STH efficiencies, which can reach upwards of 25 % for the highest performance materials in a dual stacked configuration. Higher efficiencies could be reached as improved materials are developed. The results of the modeling also identify and quantify approaches that can improve system performance when working with imperfect materials.

  19. Light harvesting proteins for solar fuel generation in bioengineered photoelectrochemical cells.

    PubMed

    Ihssen, Julian; Braun, Artur; Faccio, Greta; Gajda-Schrantz, Krisztina; Thöny-Meyer, Linda

    2014-01-01

    The sun is the primary energy source of our planet and potentially can supply all societies with more than just their basic energy needs. Demand of electric energy can be satisfied with photovoltaics, however the global demand for fuels is even higher. The direct way to produce the solar fuel hydrogen is by water splitting in photoelectrochemical (PEC) cells, an artificial mimic of photosynthesis. There is currently strong resurging interest for solar fuels produced by PEC cells, but some fundamental technological problems need to be solved to make PEC water splitting an economic, competitive alternative. One of the problems is to provide a low cost, high performing water oxidizing and oxygen evolving photoanode in an environmentally benign setting. Hematite, α-Fe2O3, satisfies many requirements for a good PEC photoanode, but its efficiency is insufficient in its pristine form. A promising strategy for enhancing photocurrent density takes advantage of photosynthetic proteins. In this paper we give an overview of how electrode surfaces in general and hematite photoanodes in particular can be functionalized with light harvesting proteins. Specifically, we demonstrate how low-cost biomaterials such as cyanobacterial phycocyanin and enzymatically produced melanin increase the overall performance of virtually no-cost metal oxide photoanodes in a PEC system. The implementation of biomaterials changes the overall nature of the photoanode assembly in a way that aggressive alkaline electrolytes such as concentrated KOH are not required anymore. Rather, a more environmentally benign and pH neutral electrolyte can be used. PMID:24678669

  20. Synthesis and characterization of nanostructured semiconductors for photovoltaic and photoelectrochemical cell applications

    NASA Astrophysics Data System (ADS)

    Sebastian, P. J.; Castañeda, Rocio; Ixtlilco, Luis; Mejia, Rogelio; Pantoja, J.; Olea, A.

    2008-08-01

    We report the synthesis and characterization of nanostructured semiconductors such as CdS, CuInSe2 (CIS) and TiO2 for photovoltaic cells and photoelectrochemical cells for hydrogen production. The CdS was prepared by chemical deposition, CuInSe2 by electrodeposition and chemical method and TiO2 by sol-gel method. All the three semiconductors were prepared in the thin film and powder form. The CdS was synthesized as wide band gap n-type material in the nanostructured form. The p-CdS was prepared also in the nanostructured form with Cu doping. P-type CuInSe2 films and powders were synthesized in the nanostructured form. TiO2 was always formed in the nanostructured and n-type form. The films and powders were characterized by x-ray diffraction, atomic force microscopy, and opto-electronic methods. All the semiconductors were formed in the nanostructured form with different band gaps depending on the particle size and post-deposition treatments.

  1. Light harvesting proteins for solar fuel generation in bioengineered photoelectrochemical cells.

    PubMed

    Ihssen, Julian; Braun, Artur; Faccio, Greta; Gajda-Schrantz, Krisztina; Thöny-Meyer, Linda

    2014-01-01

    The sun is the primary energy source of our planet and potentially can supply all societies with more than just their basic energy needs. Demand of electric energy can be satisfied with photovoltaics, however the global demand for fuels is even higher. The direct way to produce the solar fuel hydrogen is by water splitting in photoelectrochemical (PEC) cells, an artificial mimic of photosynthesis. There is currently strong resurging interest for solar fuels produced by PEC cells, but some fundamental technological problems need to be solved to make PEC water splitting an economic, competitive alternative. One of the problems is to provide a low cost, high performing water oxidizing and oxygen evolving photoanode in an environmentally benign setting. Hematite, α-Fe2O3, satisfies many requirements for a good PEC photoanode, but its efficiency is insufficient in its pristine form. A promising strategy for enhancing photocurrent density takes advantage of photosynthetic proteins. In this paper we give an overview of how electrode surfaces in general and hematite photoanodes in particular can be functionalized with light harvesting proteins. Specifically, we demonstrate how low-cost biomaterials such as cyanobacterial phycocyanin and enzymatically produced melanin increase the overall performance of virtually no-cost metal oxide photoanodes in a PEC system. The implementation of biomaterials changes the overall nature of the photoanode assembly in a way that aggressive alkaline electrolytes such as concentrated KOH are not required anymore. Rather, a more environmentally benign and pH neutral electrolyte can be used.

  2. Reversible chemical tuning of charge carriers for enhanced photoelectrochemical conversion and probing of living cells.

    PubMed

    Wang, Yongcheng; Tang, Jing; Zhou, Tong; Da, Peimei; Li, Jun; Kong, Biao; Yang, Zhongqin; Zheng, Gengfeng

    2014-12-10

    A facile, solution method for reversible tuning of oxygen vacancies inside TiO2 nanowires, in which the reducing treatment of TiO2 by NaBH4 leads to 2.4-fold increase of photocurrent density, compared to pristine TiO2 nanowires, is reported. Subsequent oxidizing treatment using KMnO4 or annealing in air can reset the photocurrent density to the original values. The incident photo-to-current conversion efficiency measurement exhibits that the reduced TiO2 nanowires present both enhanced photoactivity in both UV and visible regions. Density functional theory calculations reveal that the oxygen vacancies in the reduced TiO2 cause defect states in the band structure and result in enhanced carrier density and conductivity. In addition, the enhanced solar energy-driven photoelectrochemical conversion allows real-time, sensitive chemical probing of living cells that are directly grown on the TiO2 nanowire photoanodes. As proofs-of-concept, after functionalized with horseradish peroxidase (HRP) on the surface, the reduced TiO2 NWs demonstrate sensitive, real-time monitoring of the H2O2 levels in several distinctive living cell lines, with the lowest detectable H2O2 concentration of 7.7 nM. This reversible tuning of oxygen vacancies suggests a facile means for transition metal oxides, with enhanced photoconversion activity and electrochemical sensitivity. PMID:25044916

  3. Light Harvesting Proteins for Solar Fuel Generation in Bioengineered Photoelectrochemical Cells

    PubMed Central

    Ihssen, Julian; Braun, Artur; Faccio, Greta; Gajda-Schrantz, Krisztina; Thöny-Meyer, Linda

    2014-01-01

    The sun is the primary energy source of our planet and potentially can supply all societies with more than just their basic energy needs. Demand of electric energy can be satisfied with photovoltaics, however the global demand for fuels is even higher. The direct way to produce the solar fuel hydrogen is by water splitting in photoelectrochemical (PEC) cells, an artificial mimic of photosynthesis. There is currently strong resurging interest for solar fuels produced by PEC cells, but some fundamental technological problems need to be solved to make PEC water splitting an economic, competitive alternative. One of the problems is to provide a low cost, high performing water oxidizing and oxygen evolving photoanode in an environmentally benign setting. Hematite, α-Fe2O3, satisfies many requirements for a good PEC photoanode, but its efficiency is insufficient in its pristine form. A promising strategy for enhancing photocurrent density takes advantage of photosynthetic proteins. In this paper we give an overview of how electrode surfaces in general and hematite photoanodes in particular can be functionalized with light harvesting proteins. Specifically, we demonstrate how low-cost biomaterials such as cyanobacterial phycocyanin and enzymatically produced melanin increase the overall performance of virtually no-cost metal oxide photoanodes in a PEC system. The implementation of biomaterials changes the overall nature of the photoanode assembly in a way that aggressive alkaline electrolytes such as concentrated KOH are not required anymore. Rather, a more environmentally benign and pH neutral electrolyte can be used. PMID:24678669

  4. Revealing the charge transport mechanism of a photoelectrochemical cell: analysis using A.C. voltage perturbation.

    PubMed

    Patel, Dipal B; Chauhan, Khushbu R; Mukhopadhyay, Indrajit

    2014-10-14

    In this paper, we have carefully investigated the operation of a photoelectrochemical (PEC) cell configured of PbOx|Fe(CN)6(-4/-3)|Pt in the accumulation, flat band, depletion, inversion and deep-depletion regions using impedance measurements. The increases in the photocurrent for the different regions differ in their nature: a logarithmic increase in the depletion region, a linear increase in the inversion region along with a linear increase in the dark current and an exponential increase in the photo- and dark current in the deep-depletion region. All these variations are studied in detail to correlate these observations to the charge transfer mechanisms. The characteristics of the impedance spectrum itself can be assigned to the mentioned regions. We have found that the maximum photocurrent of the PEC cell, in the present investigation, can be extracted when the cell is working in the inversion region, while the maximum rate of the increase in photocurrent is found when the junction behaves as an ideal Schottky diode with a single RC element. Systematic experiments are suggested to establish a correlation between the observations obtained from the photocurrent, impedance, conductance, low frequency and high frequency capacitance measurements. It was found that light induced trap states in the semiconductor limit the photocurrent which has a linear dependency on the irradiance. A detailed investigation with A.C. conductivity measurements showed that the trap states actively participate in the current mechanism via a hopping phenomenon with small activation energies of 0.2 and 0.8 meV. The hopping rate increased exponentially with the applied bias under dark and illumination conditions. We also show a new way of finding the potential at which the maximum photocurrent will be extracted from the PEC cell, wherein the hopping via trap states is a dominating charge transfer mechanism. This study will help in pin pointing the key affecting parameters which limit the

  5. Improved Photoelectrochemical Cell Performance of Tin Oxide with Functionalized Multiwalled Carbon Nanotubes-Cadmium Selenide Sensitizer.

    PubMed

    Bhande, Sambhaji S; Ambade, Rohan B; Shinde, Dipak V; Ambade, Swapnil B; Patil, Supriya A; Naushad, Mu; Mane, Rajaram S; Alothman, Z A; Lee, Soo-Hyoung; Han, Sung-Hwan

    2015-11-18

    Here we report functionalized multiwalled carbon nanotubes (f-MWCNTs)-CdSe nanocrystals (NCs) as photosensitizer in photoelectrochemical cells, where f-MWCNTs were uniformly coated with CdSe NCs onto SnO2 upright standing nanosheets by using a simple electrodeposition method. The resultant blended photoanodes demonstrate extraordinary electrochemical properties including higher Stern-Volmer constant, higher absorbance, and positive quenching, etc., caused by more accessibility of CdSe NCs compared with pristine SnO2-CdSe photoanode. Atomic and weight percent changes of carbon with f-MWCNTs blending concentrations were confirmed from the energy dispersive X-ray analysis. The morphology images show a uniform coverage of CdSe NCs over f-MWCNTs forming a core-shell type structure as a blend. Compared to pristine CdSe, photoanode with f-MWCNTs demonstrated a 257% increase in overall power conversion efficiency. Obtained results were corroborated by the electrochemical impedance analysis. Higher scattering, more accessibility, and hierarchical structure of SnO2-f-MWCNTs-blend-CdSe NCs photoanode is responsible for higher (a) electron mobility (6.89 × 10(-4) to 10.89 × 10(-4) cm(2) V(-1) S(1-)), (b) diffusion length (27 × 10(-6)),

  6. Structural effects on the photoelectrochemical properties of new push-pull dyes based on vinazene acceptor triphenylamine donor

    NASA Astrophysics Data System (ADS)

    Arcos, Wilmmer A.; Guimarães, Robson R.; Insuasty, Braulio; Araki, Koiti; Ortiz, Alejandro

    2016-05-01

    The push-pull behavior of novel dyes, based on vinazene electron-acceptor groups linked to arrays of triphenylamine (TPA) electron-donor group, was studied by electronic absorption and emission spectroscopy, as well as by cyclic voltammetry. The most stable ground state structure and their electronic properties were modeled by density functional theory (DFT) calculations using the B3LYP functional and 6-31G++ basis set, whereas the electronic properties in the excited states were calculated by TD-DFT, under the same functional and basis set, using SCF and PCM methods. The theoretical calculations matched well with experimental data, showing that λmax of the lowest energy absorption band can be assigned to an intramolecular charge transfer transition. In fact, the HOMO and LUMO are respectively localized on the TPA donor and the dicyanomethylene acceptor moiety confirming a remarkable push-pull character. Photoelectrochemical cells parameters were correlated with dyes structural properties showing to be consistent with the anchoring through the nitrogen atoms of CN groups. The nature of the donor-acceptor groups, conformation and number of anchoring CN groups (2 seems to be the best) strongly influenced the overall efficiency of dye sensitized solar cells.

  7. Target-induced nano-enzyme reactor mediated hole-trapping for high-throughput immunoassay based on a split-type photoelectrochemical detection strategy.

    PubMed

    Zhuang, Junyang; Tang, Dianyong; Lai, Wenqiang; Xu, Mingdi; Tang, Dianping

    2015-09-15

    Photoelectrochemical (PEC) detection is an emerging and promising analytical tool. However, its actual application still faces some challenges like potential damage of biomolecules (caused by itself system) and intrinsic low-throughput detection. To solve the problems, herein we design a novel split-type photoelectrochemical immunoassay (STPIA) for ultrasensitive detection of prostate specific antigen (PSA). Initially, the immunoreaction was performed on a microplate using a secondary antibody/primer-circular DNA-labeled gold nanoparticle as the detection tag. Then, numerously repeated oligonucleotide sequences with many biotin moieties were in situ synthesized on the nanogold tag via RCA reaction. The formed biotin concatamers acted as a powerful scaffold to bind with avidin-alkaline phosphatase (ALP) conjugates and construct a nanoenzyme reactor. By this means, enzymatic hydrolysate (ascorbic acid) was generated to capture the photogenerated holes in the CdS quantum dot-sensitized TiO2 nanotube arrays, resulting in amplification of the photocurrent signal. To elaborate, the microplate-based immunoassay and the high-throughput detection system, a semiautomatic detection cell (installed with a three-electrode system), was employed. Under optimal conditions, the photocurrent increased with the increasing PSA concentration in a dynamic working range from 0.001 to 3 ng mL(-1), with a low detection limit (LOD) of 0.32 pg mL(-1). Meanwhile, the developed split-type photoelectrochemical immunoassay exhibited high specificity and acceptable accuracy for analysis of human serum specimens in comparison with referenced electrochemiluminescence immunoassay method. Importantly, the system was not only suitable for the sandwich-type immunoassay mode, but also utilized for the detection of small molecules (e.g., aflatoxin B1) with a competitive-type assay format.

  8. Visible photoelectrochemical water splitting into H2 and O2 in a dye-sensitized photoelectrosynthesis cell.

    PubMed

    Alibabaei, Leila; Sherman, Benjamin D; Norris, Michael R; Brennaman, M Kyle; Meyer, Thomas J

    2015-05-12

    A hybrid strategy for solar water splitting is exploited here based on a dye-sensitized photoelectrosynthesis cell (DSPEC) with a mesoporous SnO2/TiO2 core/shell nanostructured electrode derivatized with a surface-bound Ru(II) polypyridyl-based chromophore-catalyst assembly. The assembly, [(4,4'-(PO3H2)2bpy)2Ru(4-Mebpy-4'-bimpy)Ru(tpy)(OH2)](4+) ([Ru(a) (II)-Ru(b) (II)-OH2](4+), combines both a light absorber and a water oxidation catalyst in a single molecule. It was attached to the TiO2 shell by phosphonate-surface oxide binding. The oxide-bound assembly was further stabilized on the surface by atomic layer deposition (ALD) of either Al2O3 or TiO2 overlayers. Illumination of the resulting fluorine-doped tin oxide (FTO)|SnO2/TiO2|-[Ru(a) (II)-Ru(b) (II)-OH2](4+)(Al2O3 or TiO2) photoanodes in photoelectrochemical cells with a Pt cathode and a small applied bias resulted in visible-light water splitting as shown by direct measurements of both evolved H2 and O2. The performance of the resulting DSPECs varies with shell thickness and the nature and extent of the oxide overlayer. Use of the SnO2/TiO2 core/shell compared with nanoITO/TiO2 with the same assembly results in photocurrent enhancements of ∼ 5. Systematic variations in shell thickness and ALD overlayer lead to photocurrent densities as high as 1.97 mA/cm(2) with 445-nm, ∼ 90-mW/cm(2) illumination in a phosphate buffer at pH 7. PMID:25918426

  9. In situ-generated nano-gold plasmon-enhanced photoelectrochemical aptasensing based on carboxylated perylene-functionalized graphene.

    PubMed

    Li, Jing; Tu, Wenwen; Li, Hongbo; Han, Min; Lan, Yaqian; Dai, Zhihui; Bao, Jianchun

    2014-01-21

    A novel in situ-generated nanogold plasmon-enhanced photoelectrochemical aptasensor for Hg(2+) ions was fabricated using a perylene-3,4,9,10-tetracarboxylic acid/graphene (PTCA-GR) heterojunction. The fabricated photoelectrochemical aptasensor was based on thymine-Hg(2+)-thymine coordination chemistry and the plasmonic near-field absorption enhancement effect of the subsequent specific catalytic formation of nanogold. The energetic electrons from the surface plasmons of the nanogold were injected into the LUMO orbit of the organic PTCA semiconductor and then rapidly transferred to the electrode through GR due to the possible Hg(2+)-DNA molecular wires following irradiation with the visible light (λ > 450 nm) and at a bias voltage of 0.2 V. The fabricated aptasensor was linear in its response to the concentration of Hg(2+) ions in the range of 5-500 pmol L(-1), with a detection limit of 2 pmol L(-1). The presence of up to 200-fold greater concentrations of other common metal ions did not interfere with the detection of Hg(2+) ions in an aqueous system, and the results corresponded well with those obtained by ICP-MS. This novel plasmon-enhanced photoelectrochemical aptasensor exhibited good performance with its high sensitivity, good selectivity, low cost, and portable features. The strategy of the localized surface plasmon resonance through the in situ generation of noble metal nanoparticles paves the way for improvements in PEC aptasensor performance. PMID:24377281

  10. In situ-generated nano-gold plasmon-enhanced photoelectrochemical aptasensing based on carboxylated perylene-functionalized graphene.

    PubMed

    Li, Jing; Tu, Wenwen; Li, Hongbo; Han, Min; Lan, Yaqian; Dai, Zhihui; Bao, Jianchun

    2014-01-21

    A novel in situ-generated nanogold plasmon-enhanced photoelectrochemical aptasensor for Hg(2+) ions was fabricated using a perylene-3,4,9,10-tetracarboxylic acid/graphene (PTCA-GR) heterojunction. The fabricated photoelectrochemical aptasensor was based on thymine-Hg(2+)-thymine coordination chemistry and the plasmonic near-field absorption enhancement effect of the subsequent specific catalytic formation of nanogold. The energetic electrons from the surface plasmons of the nanogold were injected into the LUMO orbit of the organic PTCA semiconductor and then rapidly transferred to the electrode through GR due to the possible Hg(2+)-DNA molecular wires following irradiation with the visible light (λ > 450 nm) and at a bias voltage of 0.2 V. The fabricated aptasensor was linear in its response to the concentration of Hg(2+) ions in the range of 5-500 pmol L(-1), with a detection limit of 2 pmol L(-1). The presence of up to 200-fold greater concentrations of other common metal ions did not interfere with the detection of Hg(2+) ions in an aqueous system, and the results corresponded well with those obtained by ICP-MS. This novel plasmon-enhanced photoelectrochemical aptasensor exhibited good performance with its high sensitivity, good selectivity, low cost, and portable features. The strategy of the localized surface plasmon resonance through the in situ generation of noble metal nanoparticles paves the way for improvements in PEC aptasensor performance.

  11. Cyclometalated iridium complex-based label-free photoelectrochemical biosensor for DNA detection by hybridization chain reaction amplification.

    PubMed

    Li, Chunxiang; Wang, Hongyang; Shen, Jing; Tang, Bo

    2015-04-21

    Photoactive material is the most crucial factor which intimately determines analytical performances of the photoelectrochemical sensor. On the basis of the high affinity of dipyrido [3,2-a:2',3'-c] phenazine (dppz) with DNA helix, a novel photoactive intercalator, [(ppy)2Ir(dppz)](+)PF6(-)(ppy = 2-phenylpyridine and dppz = dipyrido [3,2-a:2',3'-c] phenazine) was prepared and characterized by UV-vis absorption spectroscopy, fluorescence spectroscopy, and cyclic voltammetry. The photoelectrochemical properties of the as-prepared iridium(III) complex immobilized on the ITO electrode was investigated. Either cathodic or anodic photocurrent generation can be observed when triethanolamine (TEOA) or dissolved O2 is used as a sacrificial electron donor/acceptor, respectively. The probable photocurrent-generation mechanisms are speculated. A highly sensitive iridium(III) complex-based photoelectrochemical sensor was proposed for DNA detection via hybridization chain reaction (HCR) signal amplification. Under optimal conditions, the biosensor was found to be linearly proportional to the logarithm of target DNA concentration in the range from 0.025 to 100 pmol L(-1) with a detection limit of 9.0 fmol L(-1) (3σ). Moreover, the proposed sensor displayed high selectivity and good reproducibility, demonstrating efficient and stable photoelectric conversion ability of the Ir(III) complex. PMID:25816127

  12. Investigation of a Photoelectrochemical Passivated ZnO-Based Glucose Biosensor

    PubMed Central

    Lee, Ching-Ting; Chiu, Ying-Shuo; Ho, Shu-Ching; Lee, Yao-Jung

    2011-01-01

    A vapor cooling condensation system was used to deposit high quality intrinsic ZnO thin films and intrinsic ZnO nanorods as the sensing membrane of extended-gate field-effect-transistor (EGFET) glucose biosensors. The sensing sensitivity of the resulting glucose biosensors operated in the linear range was 13.4 μA mM−1 cm−2. To improve the sensing sensitivity of the ZnO-based glucose biosensors, the photoelectrochemical method was utilized to passivate the sidewall surfaces of the ZnO nanorods. The sensing sensitivity of the ZnO-based glucose biosensors with passivated ZnO nanorods was significantly improved to 20.33 μA mM−1 cm−2 under the same measurement conditions. The experimental results verified that the sensing sensitivity improvement was the result of the mitigation of the Fermi level pinning effect caused by the dangling bonds and the surface states induced on the sidewall surface of the ZnO nanorods. PMID:22163867

  13. Semiconductor-based photoelectrochemical water splitting at the limit of very wide depletion region

    DOE PAGES

    Liu, Mingzhao; Lyons, John L.; Yan, Danhua H.; Hybertsen, Mark S.

    2015-11-23

    In semiconductor-based photoelectrochemical (PEC) water splitting, carrier separation and delivery largely relies on the depletion region formed at the semiconductor/water interface. As a Schottky junction device, the trade-off between photon collection and minority carrier delivery remains a persistent obstacle for maximizing the performance of a water splitting photoelectrode. Here, it is demonstrated that the PEC water splitting efficiency for an n-SrTiO3 (n-STO) photoanode is improved very significantly despite its weak indirect band gap optical absorption (α < 10⁴ cm⁻¹), by widening the depletion region through engineering its doping density and profile. Graded doped n-SrTiO3 photoanodes are fabricated with their bulkmore » heavily doped with oxygen vacancies but their surface lightly doped over a tunable depth of a few hundred nanometers, through a simple low temperature re-oxidation technique. The graded doping profile widens the depletion region to over 500 nm, thus leading to very efficient charge carrier separation and high quantum efficiency (>70%) for the weak indirect transition. As a result, this simultaneous optimization of the light absorption, minority carrier (hole) delivery, and majority carrier (electron) transport by means of a graded doping architecture may be useful for other indirect band gap photocatalysts that suffer from a similar problem of weak optical absorption.« less

  14. Hematite-based photoelectrochemical water splitting supported by inverse opal structures of graphene.

    PubMed

    Yoon, Ki-Yong; Lee, Jung-Soo; Kim, Kwanghyun; Bak, Chang Hong; Kim, Sun-I; Kim, Jin-Baek; Jang, Ji-Hyun

    2014-12-24

    By coupling α-Fe2O3 with a 3D graphene inverse opal (3D-GIO) conducting electrode, the short diffusion length of carriers and low absorption coefficient in α-Fe2O3 for photoelectrochemical applications were successfully addressed. GIO was directly grown on FTO substrate under low temperature conditions, removing the need for a graphene transfer process. α-Fe2O3 nanoparticles (NPs) were hydrothermally deposited on the surface of GIO, creating α-Fe2O3/GIO. The photocurrent density of α-Fe2O3/GIO in water splitting reactions reached 1.62 mA/cm(2) at 1.5 V vs RHE, which is 1.4 times greater than that of optimized α-Fe2O3. The EIS and IPCE data confirm reduced electron-hole recombination and fast electron transfer processes due to the short distance between active materials and the conducting electrode in the α-Fe2O3/GIO system. Our result may pave the way for designing devices in advanced energy conversion applications as well as a high efficiency hematite-based PEC system.

  15. Hematite-based photoelectrochemical water splitting supported by inverse opal structures of graphene.

    PubMed

    Yoon, Ki-Yong; Lee, Jung-Soo; Kim, Kwanghyun; Bak, Chang Hong; Kim, Sun-I; Kim, Jin-Baek; Jang, Ji-Hyun

    2014-12-24

    By coupling α-Fe2O3 with a 3D graphene inverse opal (3D-GIO) conducting electrode, the short diffusion length of carriers and low absorption coefficient in α-Fe2O3 for photoelectrochemical applications were successfully addressed. GIO was directly grown on FTO substrate under low temperature conditions, removing the need for a graphene transfer process. α-Fe2O3 nanoparticles (NPs) were hydrothermally deposited on the surface of GIO, creating α-Fe2O3/GIO. The photocurrent density of α-Fe2O3/GIO in water splitting reactions reached 1.62 mA/cm(2) at 1.5 V vs RHE, which is 1.4 times greater than that of optimized α-Fe2O3. The EIS and IPCE data confirm reduced electron-hole recombination and fast electron transfer processes due to the short distance between active materials and the conducting electrode in the α-Fe2O3/GIO system. Our result may pave the way for designing devices in advanced energy conversion applications as well as a high efficiency hematite-based PEC system. PMID:25469502

  16. Semiconductor-based photoelectrochemical water splitting at the limit of very wide depletion region

    SciTech Connect

    Liu, Mingzhao; Lyons, John L.; Yan, Danhua H.; Hybertsen, Mark S.

    2015-11-23

    In semiconductor-based photoelectrochemical (PEC) water splitting, carrier separation and delivery largely relies on the depletion region formed at the semiconductor/water interface. As a Schottky junction device, the trade-off between photon collection and minority carrier delivery remains a persistent obstacle for maximizing the performance of a water splitting photoelectrode. Here, it is demonstrated that the PEC water splitting efficiency for an n-SrTiO3 (n-STO) photoanode is improved very significantly despite its weak indirect band gap optical absorption (α < 10⁴ cm⁻¹), by widening the depletion region through engineering its doping density and profile. Graded doped n-SrTiO3 photoanodes are fabricated with their bulk heavily doped with oxygen vacancies but their surface lightly doped over a tunable depth of a few hundred nanometers, through a simple low temperature re-oxidation technique. The graded doping profile widens the depletion region to over 500 nm, thus leading to very efficient charge carrier separation and high quantum efficiency (>70%) for the weak indirect transition. As a result, this simultaneous optimization of the light absorption, minority carrier (hole) delivery, and majority carrier (electron) transport by means of a graded doping architecture may be useful for other indirect band gap photocatalysts that suffer from a similar problem of weak optical absorption.

  17. Self-deposition of Pt nanoparticles on graphene woven fabrics for enhanced hybrid Schottky junctions and photoelectrochemical solar cells.

    PubMed

    Kang, Zhe; Tan, Xinyu; Li, Xiao; Xiao, Ting; Zhang, Li; Lao, Junchao; Li, Xinming; Cheng, Shan; Xie, Dan; Zhu, Hongwei

    2016-01-21

    In this study, we demonstrated a self-deposition method to deposit Pt nanoparticles (NPs) on graphene woven fabrics (GWF) to improve the performance of graphene-on-silicon solar cells. The deposition of Pt NPs increased the work function of GWF and reduced the sheet resistance of GWF, thereby improving the power conversion efficiency (PCE) of graphene-on-silicon solar cells. The PCE (>10%) was further enhanced via solid electrolyte coating of the hybrid Schottky junction in the photoelectrochemical solar cells. These results suggest that the combination of self-deposition of Pt NPs and solid-state electrolyte coating of graphene-on-silicon is a promising way to produce high performance graphene-on-semiconductor solar cells. PMID:26686903

  18. Self-Enhanced Ultrasensitive Photoelectrochemical Biosensor Based on Nanocapsule Packaging Both Donor-Acceptor-Type Photoactive Material and Its Sensitizer.

    PubMed

    Zheng, Ying-Ning; Liang, Wen-Bin; Xiong, Cheng-Yi; Yuan, Ya-Li; Chai, Ya-Qin; Yuan, Ruo

    2016-09-01

    In this work, a self-enhanced ultrasensitive photoelectrochemical (PEC) biosensor was established based on a functionalized nanocapsule packaging both donor-acceptor-type photoactive material and its sensitizer. The functionalized nanocapsule with self-enhanced PEC responses was achieved first by packaging both the donor-acceptor-type photoactive material (poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}, PTB7-Th) and its sensitizer (nano-C60, fullerene) in poly(ethylene glycol) (PEG) to form a nanocapsule, which significantly enhanced PEC signal and stability of the PEC biosensor. Moreover, a quadratic enzymes-assisted target recycling amplification strategy was introduced to the system for ultrasensitive determination. Compared with other established PEC biosensors, our proposed self-enhanced approach showed higher effectivity, accuracy, sensitivity, and convenience without any addition of coreactant or sensitizers into the testing electrolyte for photocurrent amplification and performed excellent analytical properties for microRNA estimation down to femtomole level with microRNA-141 as a model. Additionally, the proposed PEC biosensor was employed for estimation of microRNA in different cancer cells and pharmacodynamic evaluation in cancer cells. This self-enhanced PEC strategy has laid the foundation for fabrication of simple, effective, and ultrasensitive PEC diagnostic devices, leading to the possibility for early diagnosis, timely stage estimation, and accurate prognosis judgment of disease. PMID:27513736

  19. Self-Enhanced Ultrasensitive Photoelectrochemical Biosensor Based on Nanocapsule Packaging Both Donor-Acceptor-Type Photoactive Material and Its Sensitizer.

    PubMed

    Zheng, Ying-Ning; Liang, Wen-Bin; Xiong, Cheng-Yi; Yuan, Ya-Li; Chai, Ya-Qin; Yuan, Ruo

    2016-09-01

    In this work, a self-enhanced ultrasensitive photoelectrochemical (PEC) biosensor was established based on a functionalized nanocapsule packaging both donor-acceptor-type photoactive material and its sensitizer. The functionalized nanocapsule with self-enhanced PEC responses was achieved first by packaging both the donor-acceptor-type photoactive material (poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}, PTB7-Th) and its sensitizer (nano-C60, fullerene) in poly(ethylene glycol) (PEG) to form a nanocapsule, which significantly enhanced PEC signal and stability of the PEC biosensor. Moreover, a quadratic enzymes-assisted target recycling amplification strategy was introduced to the system for ultrasensitive determination. Compared with other established PEC biosensors, our proposed self-enhanced approach showed higher effectivity, accuracy, sensitivity, and convenience without any addition of coreactant or sensitizers into the testing electrolyte for photocurrent amplification and performed excellent analytical properties for microRNA estimation down to femtomole level with microRNA-141 as a model. Additionally, the proposed PEC biosensor was employed for estimation of microRNA in different cancer cells and pharmacodynamic evaluation in cancer cells. This self-enhanced PEC strategy has laid the foundation for fabrication of simple, effective, and ultrasensitive PEC diagnostic devices, leading to the possibility for early diagnosis, timely stage estimation, and accurate prognosis judgment of disease.

  20. Electricity generation and pollutant degradation using a novel biocathode coupled photoelectrochemical cell.

    PubMed

    Du, Yue; Feng, Yujie; Qu, Youpeng; Liu, Jia; Ren, Nanqi; Liu, Hong

    2014-07-01

    The photoelectrochemical cell (PEC) is a promising tool for the degradation of organic pollutants and simultaneous electricity recovery, however, current cathode catalysts suffer from high costs and short service lives. Herein, we present a novel biocathode coupled PEC (Bio-PEC) integrating the advantages of photocatalytic anode and biocathode. Electrochemical anodized TiO2 nanotube arrays fabricated on Ti substrate were used as Bio-PEC anodes. Field-emission scanning electron microscope images revealed that the well-aligned TiO2 nanotubes had inner diameters of 60-100 nm and wall-thicknesses of about 5 nm. Linear sweep voltammetry presented the pronounced photocurrent output (325 μA/cm(2)) under xenon illumination, compared with that under dark conditions. Comparing studies were carried out between the Bio-PEC and PECs with Pt/C cathodes. The results showed that the performance of Pt/C cathodes was closely related with the structure and Pt/C loading amounts of cathodes, while the Bio-PEC achieved similar methyl orange (MO) decoloration rate (0.0120 min(-1)) and maximum power density (211.32 mW/m(2)) to the brush cathode PEC with 50 mg Pt/C loading (Brush-PEC, 50 mg). The fill factors of Bio-PEC and Brush-PEC (50 mg) were 39.87% and 43.06%, respectively. The charge transfer resistance of biocathode was 13.10 Ω, larger than the brush cathode with 50 mg Pt/C (10.68 Ω), but smaller than the brush cathode with 35 mg Pt/C (18.35 Ω), indicating the comparable catalytic activity with Pt/C catalyst. The biocathode was more dependent on the nutrient diffusion, such as nitrogen and inorganic carbon, thus resulting in relatively higher diffusion resistance compared to the brush cathode with 50 mg Pt/C loading that yielded similar MO removal and power output. Considering the performance and cost of PEC system, the biocathode was a promising alternative for the Pt/C catalyst. PMID:24863439

  1. Electricity generation and pollutant degradation using a novel biocathode coupled photoelectrochemical cell.

    PubMed

    Du, Yue; Feng, Yujie; Qu, Youpeng; Liu, Jia; Ren, Nanqi; Liu, Hong

    2014-07-01

    The photoelectrochemical cell (PEC) is a promising tool for the degradation of organic pollutants and simultaneous electricity recovery, however, current cathode catalysts suffer from high costs and short service lives. Herein, we present a novel biocathode coupled PEC (Bio-PEC) integrating the advantages of photocatalytic anode and biocathode. Electrochemical anodized TiO2 nanotube arrays fabricated on Ti substrate were used as Bio-PEC anodes. Field-emission scanning electron microscope images revealed that the well-aligned TiO2 nanotubes had inner diameters of 60-100 nm and wall-thicknesses of about 5 nm. Linear sweep voltammetry presented the pronounced photocurrent output (325 μA/cm(2)) under xenon illumination, compared with that under dark conditions. Comparing studies were carried out between the Bio-PEC and PECs with Pt/C cathodes. The results showed that the performance of Pt/C cathodes was closely related with the structure and Pt/C loading amounts of cathodes, while the Bio-PEC achieved similar methyl orange (MO) decoloration rate (0.0120 min(-1)) and maximum power density (211.32 mW/m(2)) to the brush cathode PEC with 50 mg Pt/C loading (Brush-PEC, 50 mg). The fill factors of Bio-PEC and Brush-PEC (50 mg) were 39.87% and 43.06%, respectively. The charge transfer resistance of biocathode was 13.10 Ω, larger than the brush cathode with 50 mg Pt/C (10.68 Ω), but smaller than the brush cathode with 35 mg Pt/C (18.35 Ω), indicating the comparable catalytic activity with Pt/C catalyst. The biocathode was more dependent on the nutrient diffusion, such as nitrogen and inorganic carbon, thus resulting in relatively higher diffusion resistance compared to the brush cathode with 50 mg Pt/C loading that yielded similar MO removal and power output. Considering the performance and cost of PEC system, the biocathode was a promising alternative for the Pt/C catalyst.

  2. Photoelectrochemical water splitting with mesoporous hematite prepared by a solution-based colloidal approach.

    PubMed

    Sivula, Kevin; Zboril, Radek; Le Formal, Florian; Robert, Rosa; Weidenkaff, Anke; Tucek, Jiri; Frydrych, Jiri; Grätzel, Michael

    2010-06-01

    Sustainable hydrogen production through photoelectrochemical water splitting using hematite (alpha-Fe(2)O(3)) is a promising approach for the chemical storage of solar energy, but is complicated by the material's nonoptimal optoelectronic properties. Nanostructuring approaches have been shown to increase the performance of hematite, but the ideal nanostructure giving high efficiencies for all absorbed light wavelengths remains elusive. Here, we report for the first time mesoporous hematite photoelectodes prepared by a solution-based colloidal method which yield water-splitting photocurrents of 0.56 mA cm(-2) under standard conditions (AM 1.5G 100 mW cm(-2), 1.23 V vs reversible hydrogen electrode, RHE) and over 1.0 mA cm(-2) before the dark current onset (1.55 V vs RHE). The sintering temperature is found to increase the average particle size, and have a drastic effect on the photoactivity. X-ray photoelectron spectroscopy and magnetic measurements using a SQUID magnetometer link this effect to the diffusion and incorporation of dopant atoms from the transparent conducting substrate. In addition, examining the optical properties of the films reveals a considerable change in the absorption coefficient and onset properties, critical aspects for hematite as a solar energy converter, as a function of the sintering temperature. A detailed investigation into hematite's crystal structure using powder X-ray diffraction with Rietveld refinement to account for these effects correlates an increase in a C(3v)-type crystal lattice distortion to the improved optical properties.

  3. A photoelectrochemical biosensor for fibroblast-like synoviocyte cell using visible light-activated NCQDs sensitized-ZnO/CH3NH3PbI3 heterojunction.

    PubMed

    Pang, Xuehui; Zhang, Yong; Pan, Jihong; Zhao, Yanxia; Chen, Yao; Ren, Xiang; Ma, Hongmin; Wei, Qin; Du, Bin

    2016-03-15

    Based on ZnO nanorods (NRs)/CH3NH3PbI3/nitrogen-doped carbon quantum dots (NCQDs) nanocomposites, the highly sensitive detection of fibroblast-like synoviocyte (FLS) cell was realized by a photoelectrochemical (PEC) biosensor. ZnO/CH3NH3PbI3/NCQDs nanocomposites were exploited as the photo-to-electron generator to produce the signal. CH3NH3PbI3 was spin-coated on ZnO surface after ZnO NRs grew on ITO electrode then by dropping on the modified electrode, NCQDs were diffused and adhered to the surface of ZnO and CH3NH3PbI3. In the presence of EDC/NHS, the combination of CH3NH3PbI3 and NCQDs was achieved by the carboxyl groups (-COOH) and amino groups (-NH2) in the preparation process. Furthermore, the capture probe of FLS cell, CD95 antibody, can be anchored by -COOH and -NH2 groups through EDC/NHS. The specific recognition between the antibody capture probes and cell targets gained high-sensitive detection for FLS cell for the first time. The developed biosensor showed a wide linear range from 1.0 × 10(4)cell/mL to 10 cell/mL and a low detection limit of 2 cell/mL. This kind of biosensor would provide a novel detection strategy for FLS cell.

  4. Highly Enhanced Photoelectrochemical Water Oxidation Efficiency Based on Triadic Quantum Dot/Layered Double Hydroxide/BiVO4 Photoanodes.

    PubMed

    Tang, Yanqun; Wang, Ruirui; Yang, Ye; Yan, Dongpeng; Xiang, Xu

    2016-08-01

    The water oxidation half-reaction is considered to be a bottleneck for achieving highly efficient solar-driven water splitting due to its multiproton-coupled four-electron process and sluggish kinetics. Herein, a triadic photoanode consisting of dual-sized CdTe quantum dots (QDs), Co-based layered double hydroxide (LDH) nanosheets, and BiVO4 particles, that is, QD@LDH@BiVO4, was designed. Two sets of consecutive Type-II band alignments were constructed to improve photogenerated electron-hole separation in the triadic structure. The efficient charge separation resulted in a 2-fold enhancement of the photocurrent of the QD@LDH@BiVO4 photoanode. A significantly enhanced oxidation efficiency reaching above 90% in the low bias region (i.e., E < 0.8 V vs RHE) could be critical in determining the overall performance of a complete photoelectrochemical cell. The faradaic efficiency for water oxidation was almost 90%. The conduction band energy of QDs is ∼1.0 V more negative than that of LDH, favorable for the electron injection to LDH and enabling a more efficient hole separation. The enhanced photon-to-current conversion efficiency and improved water oxidation efficiency of the triadic structure may result from the non-negligible contribution of hot electrons or holes generated in QDs. Such a band-matching and multidimensional triadic architecture could be a promising strategy for achieving high-efficiency photoanodes by sufficiently utilizing and maximizing the functionalities of QDs. PMID:27419597

  5. Thin film photoelectrodes of ternary chalcogenide CdSe1-xTex for photoelectrochemical solar cells applications

    NASA Astrophysics Data System (ADS)

    Das, V. D.

    1992-02-01

    The basic requirements of a good thin film photoelectrode for high efficiency photoelectrochemical (PEC) cells are low resistivity and large grain size. The large size grains lead to a reduction of the grain boundary area of the thin films, with important consequences for efficient energy conversion. The low resistivity of the photoelectrodes is required to minimize the series resistance of the PEC cell which leads to lower short circuit current. In addition, we have to tailor the band gap of the material further by adjusting the composition x in the alloy CdSe1-xTex. Low resistivity in the materials can be achieved by a careful control of the stoichiometry of the material or by doping with a proper trivalent dopant such as Ga or In. The control of the stoichiometry and the dopant concentration can be achieved by a careful control of the rate/s of deposition/s. The deposition rates should also be kept comparatively low and also the substrates should be heated to elevated temperatures so that the films formed consist of large size grains. It is advisable to also change the angle of deposition from normal incidence to an inclined deposition so that the films will tend to grow with columnar grains, which are very essential. The grain size can be further increased to some extent by carefully annealing the films in vacuum at pre-determined temperature and for a time interval. The large grain size films formed this way should be coated with very thin layers of oxides like TiO2 or In2O3 to prevent corrosion of the thin film electrodes when used in the PEC cells. Thus, by carefully controlling the various parameters as outlined above, it is possible to obtain high efficiency photo-electrochemical solar cells using these Cd-Se-Te ternary alloy thin films as photoelectrodes.

  6. Photoelectrochemical water splitting for hydrogen production with metal oxide (hematite and cupric oxide) based photocatalysts

    NASA Astrophysics Data System (ADS)

    Tang, Houwen

    Solar hydrogen is one ideal energy source to replace fossil fuel, as it is sustainable and environmentally friendly. Solar hydrogen can be generated in a number of ways. Photoelectrochemical (PEC) water splitting is one of the most promising methods for solar-to-chemical energy conversion. In this research project, metal oxide-based photocatalysts, especially hematite (α-Fe 2O3) and cupric oxide (CuO), were investigated for use as electrodes in PEC water splitting for solar hydrogen production. In our research project of hematite-based electrodes, we started with the incorporation of transition metal, particularly titanium (Ti), in hematite thin films to modify the valence and conduction band edges of hematite. We found that Ti impurities improve the electron conductivity of hematite and consequently lead to significantly enhanced photocurrents. We further investigated the Ti and Mg co-alloyed hematite. In this case, Ti is the donor and Mg is the acceptor in hematite. The co-alloying approach enhanced the solubility of Mg and Ti, which led to reduced electron effective mass and therefore increased electron mobility. Also, co-alloying tunes the carrier density and therefore allows the optimization of electrical conductivity. The densities of charged defects were found to be reduced, and therefore carrier recombinations were reduced. As a result, the Ti and Mg co-alloyed hematite thin films exhibited much improved performance in PEC water splitting as compared to pure hematite thin films. For the study of cupric oxide-based electrodes, we first investigated the possibility of reducing the electrode corrosion of cupric oxide in aqueous solutions by incorporating Ti as an electrode corrosion inhibitor. We found that Ti alloying can enhance the stability of cupric oxide in base solutions at the cost of reducing its crystallinity and optical absorption, and consequently lowering its photon-to-electron conversion efficiency. In order to balance the stability and the

  7. Semiconducting behavior of substituted tetra-azaporphyrin thin films in photoelectrochemical cells

    SciTech Connect

    Yanagi, H.; Tsukatani, K.; Yamaguchi, H.; Ashida, M. . Faculty of Engineering); Schlettwein, D.; Woehrle, D. . Organische und Makromolekulare Chemie)

    1993-07-01

    Phthalocyanines are well-known organic semiconductors and have attracted interest in application to electrophotography, chemical sensors, and solar energy conversion. Photoelectrochemical properties of zinc(II) and copper(II) complexes of (1) phthalocyanine, (2) tetrapyrido [2,3-b;2[prime],3[prime]-g;2[double prime],3[double prime]-1;2[prime][double prime],3[prime][double prime]-q]-5,10,15,20-tetra-azaporphyrin, and (3) tetrapyrazino[b;g;1;q]-5,10,15,20-tetra-azaporphyrin, were investigated in thin-film electrodes prepared by vacuum deposition (VD), drop-casting (DC) and in situ synthesis (IS). The opposing behavior, photoreduction at electrodes of 1 and photo-oxidation at electrodes of 2 and 3, are discussed in terms of a band-energy shift of tetra-azaporphyrin macrocycles caused by substitution with heterocyclic pyrido and pyrazino groups. The photoelectrochemical efficiency of the electrodes is strongly affected by the film morphology which is dependent on the preparation methods, and increased in order of DC

  8. A new photoelectrochemical biosensors based on DNA conformational changes and isothermal circular strand-displacement polymerization reaction.

    PubMed

    Zhang, Xiaoru; Xu, Yunpeng; Zhao, Yanqing; Song, Weiling

    2013-01-15

    We report a strategy for the transduction of DNA hybridization into a readily detectable photoelectrochemical signal by means of a conformational change analogous to electrochemical DNA (E-DNA) approach. To demonstrate the effect of distance change for photosensitizer to the surface of electrode on the change of photocurrent, photosensitizer Ru(bpy)(2)(dcbpy)(2+) tagged DNA stem-loop structures were self-assembled onto a nanogold modified ITO electrode. Hybridization induced a large conformational change in DNA structure, which in turn significantly altered the electron-transfer tunneling distance between the electrode and photosensitizer. The resulting change in photocurrent was proportional to the concentration of DNA in the range of 1.0×10(-10)-8.0×10(-9)M. In order to improve the sensitivity of the photoelectrochemical biosensor, an amplified detection method based on isothermal strand displacement polymerization reaction was employed. With multiple rounds of isothermal strand replication, which led to strand displacement and constituted consecutive signal amplification, a detection limit of 9.4×10(-14)M target DNA was achieved.

  9. Dye-sensitized polyoxometalate for visible-light-driven photoelectrochemical cells.

    PubMed

    Gao, Junkuo; Miao, Jianwei; Li, Yongxin; Ganguly, Rakesh; Zhao, Yang; Lev, Ovadia; Liu, Bin; Zhang, Qichun

    2015-08-28

    A simple and facile one-step method for the synthesis of an organic dye-functionalized polyoxometalate (POM) hybrid with visible-light photo-response was reported. The POM hybrid was fully characterized via single crystal XRD, powder XRD, FTIR and elemental analysis. The reaction of the organic dye with inorganic salts gave the dye-functionalized POM (MoBB3), in which the POM cluster was formed in situ. The electronic absorption peak of this hybrid was successfully extended beyond 680 nm. Photoelectrochemical measurement indicated that MoBB3 was photoresponsive under visible-light illumination, suggesting that it is an n-type (electron conductive) semiconducting material. This result might offer a method for the design of novel organic dye-functionalized POMs for photoelectric applications.

  10. Dye-sensitized polyoxometalate for visible-light-driven photoelectrochemical cells.

    PubMed

    Gao, Junkuo; Miao, Jianwei; Li, Yongxin; Ganguly, Rakesh; Zhao, Yang; Lev, Ovadia; Liu, Bin; Zhang, Qichun

    2015-08-28

    A simple and facile one-step method for the synthesis of an organic dye-functionalized polyoxometalate (POM) hybrid with visible-light photo-response was reported. The POM hybrid was fully characterized via single crystal XRD, powder XRD, FTIR and elemental analysis. The reaction of the organic dye with inorganic salts gave the dye-functionalized POM (MoBB3), in which the POM cluster was formed in situ. The electronic absorption peak of this hybrid was successfully extended beyond 680 nm. Photoelectrochemical measurement indicated that MoBB3 was photoresponsive under visible-light illumination, suggesting that it is an n-type (electron conductive) semiconducting material. This result might offer a method for the design of novel organic dye-functionalized POMs for photoelectric applications. PMID:26200796

  11. Glassy carbon/multi walled carbon nanotube/cadmium sulphide photoanode for light energy storage in vanadium photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Peimanifard, Zahra; Rashid-Nadimi, Sahar

    2015-12-01

    The aim of this study is utilizing the artificial photosynthesis, which is an attractive and challenging theme in the photoelectrocatalytic water splitting, to charge the vanadium redox flow battery (VRFB). In this work multi walled carbon nanotube/cadmium sulphide hybrid is employed as a photoanode material to oxidize VO2+ to VO2+ for charging the positive vanadium redox flow battery's half-cell. Characterization studies are also described using the scanning electron microscopic-energy-dispersive X-ray spectroscopy (SEM-EDS), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and UV-Visible methods. The phtoelectrochemical performance is characterized by cyclic voltammetry and chronoamperometry. Applied bias photon-to-current efficiency (ABPE) is achieved for both two and three-electrode configurations. The glassy carbon/multi walled carbon nanotube/cadmium sulphide yields high maximum ABPE of 2.6% and 2.12% in three and two-electrode setups, respectively. These results provide a useful guideline in designing photoelectrochemical cells for charging the vanadium redox flow batteries by sunlight as a low cost, free and abundant energy source, which does not rely on an external power input.

  12. Photoelectrochemical cell/dye-sensitized solar cell tandem water splitting systems with transparent and vertically aligned quantum dot sensitized TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Shin, Kahee; Yoo, Ji-Beom; Park, Jong Hyeok

    2013-03-01

    The present work reports fabrication of vertically aligned CdS sensitized TiO2 nanorod arrays grown on transparent conducting oxide substrate with high transparency as a photoanode in photoelectrochemical cell for water splitting. To realize an unassisted water splitting system, the photoanode and dye-sensitized solar cell tandem structures are tried and their electrochemical behaviors are also investigated. The hydrothermally grown TiO2 nanorod arrays followed by CdS nanoparticle decoration can improve the light absorption of long wavelength light resulting in increased photocurrent density. Two different techniques (electrodeposition and spray pyrolysis deposition) of CdS nanoparticle sensitization are carried out and their water splitting behaviors in the tandem cell are compared.

  13. Proton-Induced Trap States, Injection and Recombination Dynamics in Water-Splitting Dye-Sensitized Photoelectrochemical Cells.

    PubMed

    McCool, Nicholas S; Swierk, John R; Nemes, Coleen T; Saunders, Timothy P; Schmuttenmaer, Charles A; Mallouk, Thomas E

    2016-07-01

    Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) utilize a sensitized metal oxide and a water oxidation catalyst in order to generate hydrogen and oxygen from water. Although the Faradaic efficiency of water splitting is close to unity, the recombination of photogenerated electrons with oxidized dye molecules causes the quantum efficiency of these devices to be low. It is therefore important to understand recombination mechanisms in order to develop strategies to minimize them. In this paper, we discuss the role of proton intercalation in the formation of recombination centers. Proton intercalation forms nonmobile surface trap states that persist on time scales that are orders of magnitude longer than the electron lifetime in TiO2. As a result of electron trapping, recombination with surface-bound oxidized dye molecules occurs. We report a method for effectively removing the surface trap states by mildly heating the electrodes under vacuum, which appears to primarily improve the injection kinetics without affecting bulk trapping dynamics, further stressing the importance of proton control in WS-DSPECs. PMID:27295276

  14. Proton-Induced Trap States, Injection and Recombination Dynamics in Water-Splitting Dye-Sensitized Photoelectrochemical Cells.

    PubMed

    McCool, Nicholas S; Swierk, John R; Nemes, Coleen T; Saunders, Timothy P; Schmuttenmaer, Charles A; Mallouk, Thomas E

    2016-07-01

    Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) utilize a sensitized metal oxide and a water oxidation catalyst in order to generate hydrogen and oxygen from water. Although the Faradaic efficiency of water splitting is close to unity, the recombination of photogenerated electrons with oxidized dye molecules causes the quantum efficiency of these devices to be low. It is therefore important to understand recombination mechanisms in order to develop strategies to minimize them. In this paper, we discuss the role of proton intercalation in the formation of recombination centers. Proton intercalation forms nonmobile surface trap states that persist on time scales that are orders of magnitude longer than the electron lifetime in TiO2. As a result of electron trapping, recombination with surface-bound oxidized dye molecules occurs. We report a method for effectively removing the surface trap states by mildly heating the electrodes under vacuum, which appears to primarily improve the injection kinetics without affecting bulk trapping dynamics, further stressing the importance of proton control in WS-DSPECs.

  15. Metal-based anode for high performance bioelectrochemical systems through photo-electrochemical interaction

    NASA Astrophysics Data System (ADS)

    Liang, Yuxiang; Feng, Huajun; Shen, Dongsheng; Long, Yuyang; Li, Na; Zhou, Yuyang; Ying, Xianbin; Gu, Yuan; Wang, Yanfeng

    2016-08-01

    This paper introduces a novel composite anode that uses light to enhance current generation and accelerate biofilm formation in bioelectrochemical systems. The composite anode is composed of 316L stainless steel substrate and a nanostructured α-Fe2O3 photocatalyst (PSS). The electrode properties, current generation, and biofilm properties of the anode are investigated. In terms of photocurrent, the optimal deposition and heat-treatment times are found to be 30 min and 2 min, respectively, which result in a maximum photocurrent of 0.6 A m-2. The start-up time of the PSS is 1.2 days and the maximum current density is 2.8 A m-2, twice and 25 times that of unmodified anode, respectively. The current density of the PSS remains stable during 20 days of illumination. Confocal laser scanning microscope images show that the PSS could benefit biofilm formation, while electrochemical impedance spectroscopy indicates that the PSS reduce the charge-transfer resistance of the anode. Our findings show that photo-electrochemical interaction is a promising way to enhance the biocompatibility of metal anodes for bioelectrochemical systems.

  16. Photoelectrodes based upon Mo:BiVO4 inverse opals for photoelectrochemical water splitting.

    PubMed

    Zhou, Min; Bao, Jian; Xu, Yang; Zhang, Jiajia; Xie, Junfeng; Guan, Meili; Wang, Chengliang; Wen, Liaoyong; Lei, Yong; Xie, Yi

    2014-07-22

    BiVO4 has been regarded as a promising material for photoelectrochemical water splitting, but it suffers from a major challenge on charge collection and utilization. In order to meet this challenge, we design a nanoengineered three-dimensional (3D) ordered macro-mesoporous architecture (a kind of inverse opal) of Mo:BiVO4 through a controllable colloidal crystal template method with the help of a sandwich solution infiltration method and adjustable post-heating time. Within expectation, a superior photocurrent density is achieved in return for this design. This enhancement originates primarily from effective charge collection and utilization according to the analysis of electrochemical impedance spectroscopy and so on. All the results highlight the great significance of the 3D ordered macro-mesoporous architecture as a promising photoelectrode model for the application in solar conversion. The cooperating amplification effects of nanoengineering from composition regulation and morphology innovation are helpful for creating more purpose-designed photoelectrodes with highly efficient performance. PMID:24911285

  17. Photoelectrodes based upon Mo:BiVO4 inverse opals for photoelectrochemical water splitting.

    PubMed

    Zhou, Min; Bao, Jian; Xu, Yang; Zhang, Jiajia; Xie, Junfeng; Guan, Meili; Wang, Chengliang; Wen, Liaoyong; Lei, Yong; Xie, Yi

    2014-07-22

    BiVO4 has been regarded as a promising material for photoelectrochemical water splitting, but it suffers from a major challenge on charge collection and utilization. In order to meet this challenge, we design a nanoengineered three-dimensional (3D) ordered macro-mesoporous architecture (a kind of inverse opal) of Mo:BiVO4 through a controllable colloidal crystal template method with the help of a sandwich solution infiltration method and adjustable post-heating time. Within expectation, a superior photocurrent density is achieved in return for this design. This enhancement originates primarily from effective charge collection and utilization according to the analysis of electrochemical impedance spectroscopy and so on. All the results highlight the great significance of the 3D ordered macro-mesoporous architecture as a promising photoelectrode model for the application in solar conversion. The cooperating amplification effects of nanoengineering from composition regulation and morphology innovation are helpful for creating more purpose-designed photoelectrodes with highly efficient performance.

  18. Photoelectrochemical characteristics of dye-sensitized solar cells incorporating innovative and inexpensive materials

    NASA Astrophysics Data System (ADS)

    Harlow, Lisa Jean

    The use of energy is going to continue to increase rapidly due to population and economic advances occurring throughout the world. The most widely used energies produce carbon dioxide during their combustion and have finite limits on how much of these resources are available. A strong push to utilizing renewable energy is necessary to keep up with the demand. The only renewable energy that has unlimited supply is solar. Our goal is to find cost-effective alternatives to historically the most extensively used materials in dye-sensitized solar cells. In order to rely on efficiency changes coinciding with the introduction of a new component, a standard baseline of performance is necessary to establish. A reproducible fabrication procedure composed of standard materials was instituted; the efficiency parameters exhibited a less than 10% standard deviation for any set of solar cells. Any modifications to the cell components would be apparent in the change in efficiency. Our cell modifications focused on economical alternatives to the electrolyte, the counter electrode and the chromophore. Solution-based electrolytes were replaced with a non-volatile ionic liquid, 1-methyl-3-propylimidazolium iodide, and then a poly(imidazole-functionalized) silica nanoparticle. Solid-state electrolytes reduce or prevent leakage and could ease manufacturing in large-scale devices. Platinum has been the counter electrode catalyst primarily used with the iodide/triiodide redox couple, but is a rare metal making it rather costly. We reduce platinum loading by introducing a novel counter electrode that employs platinum nanoparticles embedded on a graphene nanoplatelet paper. The highly conductive carbon base also negates the use of the expensive conductive substrate necessary for the platinum catalyst, further reducing cost. We also study the differences in transitioning from ruthenium polypyridyls to iron-based chromophores in dye-sensitized solar cells. Iron introduces low-lying ligand

  19. N-doped TiO2 based visible light activated label-free photoelectrochemical biosensor for detection of Hg(2+) through quenching of photogenerated electrons.

    PubMed

    Han, Qianqian; Wang, Kewei; Xu, Lijun; Yan, Xiang; Zhang, Kunchi; Chen, Xing; Wang, Qinglin; Zhang, Lan; Pei, Renjun

    2015-06-21

    A novel photoelectrochemical (PEC) biosensor was fabricated based on N-doped TiO2 for the detection of Hg(2+) through the quenching of photogenerated electrons. The N-doped TiO2 was synthesized by a sol-gel method with urea and tetrabutyl titanate as the N and Ti sources. Compared with the undoped TiO2, the N-doped TiO2 showed an enhanced photocurrent response under visible light (λ > 420 nm). The sensing surface was functionalized with 5'-amino-modified T-rich oligonucleotides. The photoelectrochemical biosensor bound Hg(2+) on the surface by a highly specific T-Hg(2+)-T recognition. Hg(2+) on the surface of the N-doped TiO2 film withdrew the photogenerated electrons and decreased the recorded current signal. The dynamic linear range for Hg(2+) has been determined to be as low as 2-6 μM.

  20. Probing the structural flexibility of MOFs by constructing metal oxide@MOF-based heterostructures for size-selective photoelectrochemical response

    NASA Astrophysics Data System (ADS)

    Zhan, Wenwen; He, Yue; Guo, Jiangbin; Chen, Luning; Kong, Xiangjian; Zhao, Haixia; Kuang, Qin; Xie, Zhaoxiong; Zheng, Lansun

    2016-07-01

    It is becoming a challenge to achieve simpler characterization and wider application of flexible metal organic frameworks (MOFs) exhibiting the gate-opening or breathing behavior. Herein, we designed an intelligent MOF-based system where the gate-opening or breathing behavior of MOFs can be facially visualized in solution. Two types of metal oxide@MOF core-shell heterostructures, ZnO@ZIF-7 and ZnO@ZIF-71, were prepared using ZnO nanorods as self-sacrificial templates. The structural flexibility of both the MOFs can be easily judged from the distinct molecular-size-related formation modes and photoelectrochemical performances between the two ZnO@ZIF heterostructures. Moreover, the rotational dynamics of the flexible parts of ZIF-7 were studied by analyzing the intrinsic physical properties, such as dielectric constants, of the structure. The present work reminds us to pay particular attention to the influences of the structural flexibility of MOFs on the structure and properties of MOF-involved heterostructures in future studies.It is becoming a challenge to achieve simpler characterization and wider application of flexible metal organic frameworks (MOFs) exhibiting the gate-opening or breathing behavior. Herein, we designed an intelligent MOF-based system where the gate-opening or breathing behavior of MOFs can be facially visualized in solution. Two types of metal oxide@MOF core-shell heterostructures, ZnO@ZIF-7 and ZnO@ZIF-71, were prepared using ZnO nanorods as self-sacrificial templates. The structural flexibility of both the MOFs can be easily judged from the distinct molecular-size-related formation modes and photoelectrochemical performances between the two ZnO@ZIF heterostructures. Moreover, the rotational dynamics of the flexible parts of ZIF-7 were studied by analyzing the intrinsic physical properties, such as dielectric constants, of the structure. The present work reminds us to pay particular attention to the influences of the structural flexibility of

  1. A derivative photoelectrochemical sensing platform for 4-nitrophenolate contained organophosphates pesticide based on carboxylated perylene sensitized nano-TiO2.

    PubMed

    Li, Hongbo; Li, Jing; Xu, Qin; Yang, Zhanjun; Hu, Xiaoya

    2013-03-01

    A novel visible light sensitized photoelectrochemical sensing platform was constructed based on the perylene-3,4,9,10-tetracarboxylic acid/titanium dioxide (PTCA/TiO(2)) heterojunction as the photoelectric beacon. PTCA was synthesized via facile steps of hydrolysis and neutralization reaction, and then the PTCA/TiO(2) heterojunction was easily prepared by coating PTCA on nano-TiO(2) surface. The resulting photoelectric beacon was characterized by transmission electron microscope, scanning electron microscopy, X-ray diffractometry, FTIR spectroscopy, and ultraviolet and visible spectrophotometer. Using parathion-methyl as a model, after a simple hydrolyzation process, p-nitrophenol as the hydrolysate of parathion-methyl could be obtained, the fabricated derivative photoelectrochemical sensor showed good performances with a rapid response, instrument simple and portable, low detection limit (0.08 nmol L(-1)) at a signal-to-noise ratio of 3, and good selectivity against other pesticides and possible interferences. It had been successfully applied to the detection of parathion-methyl in green vegetables and the results agreed well with that by GC-MS. This strategy not only extends the application of PTCA, but also presents a simple, economic and novel methodology for photoelectrochemical sensing.

  2. Facile fabrication of an aptasensor for thrombin based on graphitic carbon nitride/TiO2 with high visible-light photoelectrochemical activity.

    PubMed

    Fan, Dawei; Guo, Cuijuan; Ma, Hongmin; Zhao, Di; Li, Yina; Wu, Dan; Wei, Qin

    2016-01-15

    A novel aptasensor for thrombin with high visible-light activity was facilely fabricated based on graphitic carbon nitride/TiO2 (g-C3N4/TiO2) photoelectrochemical (PEC) composite. Crystallization of TiO2 nanoparticles (NPs) and their strong interaction with g-C3N4 sheet were confirmed by high-resolution transmission electron microscope (HR-TEM), both of which contributed to the high photocurrent intensity under visible-light irradiation. Carboxyl functionalized thrombin aptamers were first successfully bound to the g-C3N4/TiO2 modified electrode as proven by photoelectrochemical test and electrochemical impedance spectroscopy (EIS) analysis. Ascorbic acid was utilized as the electron donor for scavenging photo-generated holes and inhibiting light driven electron-hole pair recombination. The specific recognition between thrombin aptamer and thrombin led to the linear decrease of photocurrent with the increase of logarithm of thrombin concentration in the range of 5.0×10(-13)molL(-1) to 5.0×10(-9)molL(-1) with a detection limit of 1.2×10(-13)molL(-1). This proposed low-cost, convenient and sensitive aptasensor showed promising applications in biosensor and photoelectrochemical analysis.

  3. Self-Biased Hybrid Piezoelectric-Photoelectrochemical Cell with Photocatalytic Functionalities.

    PubMed

    Tan, Chuan Fu; Ong, Wei Li; Ho, Ghim Wei

    2015-07-28

    Utilizing solar energy for environmental and energy remediations based on photocatalytic hydrogen (H2) generation and water cleaning poses great challenges due to inadequate visible-light power conversion, high recombination rate, and intermittent availability of solar energy. Here, we report an energy-harvesting technology that utilizes multiple energy sources for development of sustainable operation of dual photocatalytic reactions. The fabricated hybrid cell combines energy harvesting from light and vibration to run a power-free photocatalytic process that exploits novel metal-semiconductor branched heterostructure (BHS) of its visible light absorption, high charge-separation efficiency, and piezoelectric properties to overcome the aforementioned challenges. The desirable characteristics of conductive flexible piezoelectrode in conjunction with pronounced light scattering of hierarchical structure originate intrinsically from the elaborate design yet facile synthesis of BHS. This self-powered photocatalysis system could potentially be used as H2 generator and water treatment system to produce clean energy and water resources.

  4. Self-Biased Hybrid Piezoelectric-Photoelectrochemical Cell with Photocatalytic Functionalities.

    PubMed

    Tan, Chuan Fu; Ong, Wei Li; Ho, Ghim Wei

    2015-07-28

    Utilizing solar energy for environmental and energy remediations based on photocatalytic hydrogen (H2) generation and water cleaning poses great challenges due to inadequate visible-light power conversion, high recombination rate, and intermittent availability of solar energy. Here, we report an energy-harvesting technology that utilizes multiple energy sources for development of sustainable operation of dual photocatalytic reactions. The fabricated hybrid cell combines energy harvesting from light and vibration to run a power-free photocatalytic process that exploits novel metal-semiconductor branched heterostructure (BHS) of its visible light absorption, high charge-separation efficiency, and piezoelectric properties to overcome the aforementioned challenges. The desirable characteristics of conductive flexible piezoelectrode in conjunction with pronounced light scattering of hierarchical structure originate intrinsically from the elaborate design yet facile synthesis of BHS. This self-powered photocatalysis system could potentially be used as H2 generator and water treatment system to produce clean energy and water resources. PMID:26122026

  5. A competitive photoelectrochemical immunosensor based on a CdS-induced signal amplification strategy for the ultrasensitive detection of dexamethasone.

    PubMed

    Wang, Xueping; Yan, Tao; Li, Yan; Liu, Yixin; Du, Bin; Ma, Hongmin; Wei, Qin

    2015-12-09

    A novel photoelectrochemical immunosensor based on the competitive strategy is proposed for the specific detection of dexamethasone (DXM). Graphitic carbon nitride coupled with bismuth sulfide are used as the sensing matrix for the immobilization of BSA-DXM on the electrode surface, while cadmium sulfide functionalized titanium dioxide (TiO2@CdS) is used as the photoelectric active labels of anti-DXM. Due to the perfect matching of energy levels between TiO2 and CdS, the in situ prepared composite labels show excellent photocurrent response under visible lights. The competitive binding of DXM in sample solutions and BSA-DXM on the electrode surface reduces the specific attachment of labels to the electrode, resulting in a decrease of the photocurrent intensity. Greatly enhanced sensitivity is achieved after the optimization of the detection conditions. Under the optimal detection condition, the well-designed immunosensor for DXM exhibits a low detection limit of 2 pg ∙ mL(-1). Additionally, the proposed immunoassay system shows high specificity, good reproducibility and acceptable stability, which is also expected to become a promising platform for the detection of other small molecules.

  6. A competitive photoelectrochemical assay for estradiol based on in situ generated CdS-enhanced TiO2.

    PubMed

    Li, Rongxia; Liu, Yixin; Yan, Tao; Li, Yueyun; Cao, Wei; Wei, Qin; Du, Bin

    2015-04-15

    A novel and simple photoelectrochemical (PEC) bioassay protocol for estradiol was proposed based on in situ generated CdS-enhanced TiO2 film via competitive strategy. The CdS was generated in situ by immediately dropping S(2-) onto the Cd(2+)-functionalized titanium phosphate nanoparticles (TiP@Cd(2+)). The TiO2 photoactive sensing film with countless active sites was obtained by calcination and further explored for estradiol (E2) capture. The TiP@Cd(2+) was used as labels and immobilized through affinity-specific binding with E2 on the surface of the electrode. Greatly enhanced sensitivity was achieved by using porous TiP nanoparticles as carriers to load a large amount of Cd(2+) and further for more CdS production through the S(2-) deposition. What's more, the photocurrent of CdS generated on the electrode surface could be significantly amplified by the coupling of CdS and TiO2, which could enhance the excitation and photo-to-electric conversion efficiency. Through the application of a competitive binding assay, the proposed biosensor showed high sensitivity with a detection limit down to 2pg/mL. This simple and fast PEC E2-sensing approach offers great promise to extend its application for the assay of small molecules of biomedical, food and environmental interest. Additionally, the strategy of employing in situ generated narrow-band gap semiconductors paves a new way for PEC sensing.

  7. A label-free photoelectrochemical aptasensor based on nitrogen-doped graphene quantum dots for chloramphenicol determination.

    PubMed

    Liu, Yong; Yan, Kai; Okoth, Otieno Kevin; Zhang, Jingdong

    2015-12-15

    A photoelectrochemical (PEC) sensing platform for chloramphenicol (CAP) detection was constructed using nitrogen-doped graphene quantum dots (N-GQDs) as transducer species and label-free aptamer as biological recognition element. N-GQDs, synthesized via a facile one-step hydrothermal method, were explored to achieve highly efficient photon-to-electricity conversion under visible light irradiation. The obtained N-GQDs were characterized by transmission electron microscopy (TEM), which displayed a narrow size distribution with a mean diameter of 2.14 nm. The X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectroscopic (FT-IR) analysis confirmed that nitrogen was successfully doped in GQDs. The UV-visible absorption spectra indicated that nitrogen doping obviously enhanced the absorption of GQDs in visible light region. As a result, the PEC activity of GQDs was promoted by nitrogen doping. Additionally, the π-conjugated structure of N-GQDs provided an excellent platform for aptamer immobilization via π-π stacking interaction. Such an aptamer/N-GQDs based sensor showed a linear PEC response to CAP concentration in the range of 10-250 nM with a detection limit (3 S/N) of 3.1 nM. The developed PEC aptasensor exhibited high sensitivity and selectivity, good reproducibility and high stability. PMID:26264269

  8. A competitive photoelectrochemical immunosensor based on a CdS-induced signal amplification strategy for the ultrasensitive detection of dexamethasone

    PubMed Central

    Wang, Xueping; Yan, Tao; Li, Yan; Liu, Yixin; Du, Bin; Ma, Hongmin; Wei, Qin

    2015-01-01

    A novel photoelectrochemical immunosensor based on the competitive strategy is proposed for the specific detection of dexamethasone (DXM). Graphitic carbon nitride coupled with bismuth sulfide are used as the sensing matrix for the immobilization of BSA-DXM on the electrode surface, while cadmium sulfide functionalized titanium dioxide (TiO2@CdS) is used as the photoelectric active labels of anti-DXM. Due to the perfect matching of energy levels between TiO2 and CdS, the in situ prepared composite labels show excellent photocurrent response under visible lights. The competitive binding of DXM in sample solutions and BSA-DXM on the electrode surface reduces the specific attachment of labels to the electrode, resulting in a decrease of the photocurrent intensity. Greatly enhanced sensitivity is achieved after the optimization of the detection conditions. Under the optimal detection condition, the well-designed immunosensor for DXM exhibits a low detection limit of 2 pg∙mL−1. Additionally, the proposed immunoassay system shows high specificity, good reproducibility and acceptable stability, which is also expected to become a promising platform for the detection of other small molecules. PMID:26648409

  9. A label-free photoelectrochemical aptasensor based on nitrogen-doped graphene quantum dots for chloramphenicol determination.

    PubMed

    Liu, Yong; Yan, Kai; Okoth, Otieno Kevin; Zhang, Jingdong

    2015-12-15

    A photoelectrochemical (PEC) sensing platform for chloramphenicol (CAP) detection was constructed using nitrogen-doped graphene quantum dots (N-GQDs) as transducer species and label-free aptamer as biological recognition element. N-GQDs, synthesized via a facile one-step hydrothermal method, were explored to achieve highly efficient photon-to-electricity conversion under visible light irradiation. The obtained N-GQDs were characterized by transmission electron microscopy (TEM), which displayed a narrow size distribution with a mean diameter of 2.14 nm. The X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectroscopic (FT-IR) analysis confirmed that nitrogen was successfully doped in GQDs. The UV-visible absorption spectra indicated that nitrogen doping obviously enhanced the absorption of GQDs in visible light region. As a result, the PEC activity of GQDs was promoted by nitrogen doping. Additionally, the π-conjugated structure of N-GQDs provided an excellent platform for aptamer immobilization via π-π stacking interaction. Such an aptamer/N-GQDs based sensor showed a linear PEC response to CAP concentration in the range of 10-250 nM with a detection limit (3 S/N) of 3.1 nM. The developed PEC aptasensor exhibited high sensitivity and selectivity, good reproducibility and high stability.

  10. Visible light photoelectrochemical aptasensor for adenosine detection based on CdS/PPy/g-C3N4 nanocomposites.

    PubMed

    Liu, Yixin; Ma, Hongmin; Zhang, Yong; Pang, Xuehui; Fan, Dawei; Wu, Dan; Wei, Qin

    2016-12-15

    In this work, a label-free photoelectrochemical (PEC) aptasensor was developed for adenosine detection based on CdS/PPy/g-C3N4 nanocomposites. The CdS/g-C3N4 heterojunction effectively prevented the photogenerated charges recombination of g-C3N4 and self-photocorrosion processes of CdS, improving photo-to-current conversion efficiency. The introduced polypyrrole (PPy) nanoparticles could lead to a more effective separation of photogenerated charges, thus resulting in a further increasing of photocurrent. The CdS/PPy/g-C3N4 was firstly employed as the photoactive materials for fabrication of aptasensor, and SH-aptamer was then adsorbed on the CdS/PPy/g-C3N4 modified electrodes through S-Cd bond. With increasing of adenosine concentration, the photocurrent decreased as the formation of SH-aptamer-adenosine bioaffinity complexes. Under optimal conditions, the PEC aptasensor had a sensitive response to adenosine in a linear range of 0.3nmolL(-1) to 200nmolL(-1) with a detection limit of 0.1nmolL(-1). Besides, the as-proposed aptasensor has also been applied in human serum samples analysis. The aptasensor exhibits high sensitivity and good stability, thus opening up a new promising PEC platform for some other small molecules analysis. PMID:27424261

  11. Interrupted chalcogenide-based zeolite-analogue semiconductor: atomically precise doping for tunable electro-/photoelectrochemical properties.

    PubMed

    Lin, Jian; Dong, Youzhen; Zhang, Qian; Hu, Dandan; Li, Na; Wang, Le; Liu, Yang; Wu, Tao

    2015-04-20

    Incorporation of semiconductor property into zeolite materials is a plausible approach to graft oxide zeolites with multifunctionality in which both electronic/optoelectronic functions and high porosity are integrated. However, creating such semiconductor zeolites, especially the ones with controllable function regulation still remains as a great synthetic challenge over the years. Hereby, we reported the first case of an interrupted chalcogenide-based zeolite-analog semiconductor with an entirely new boracite-related framework and specific sites at the interrupted section. The semiconducting nature and band structure of this open-framework n-type semiconductor material were characterized with solid-state UV/Vis diffuse reflectance spectroscopy and Mott-Schottky measurements. More importantly, the In-Se chalcogenide zeolite analog was for the first time explored as an effective electrocatalyst for the oxygen reduction reaction (ORR). The specific indium sites served as active centers and proved to be responsible for a superior ORR activity. Meanwhile, these specific sites could be precisely replaced by bismuth(III) ions, leading to facile manipulation in their electro-/photoelectrochemical properties. Such atomically precise doping successfully implemented at the semiconductor zeolite material with specifically interrupted sites presents a very promising route for accurately regulating electronic structure and photoelectrical properties of other open-framework semiconductor materials.

  12. Photoelectrochemical hydrogen production

    SciTech Connect

    Rocheleau, R.; Misra, A.; Miller, E.

    1998-08-01

    A significant component of the US DOE Hydrogen Program is the development of a practical technology for the direct production of hydrogen using a renewable source of energy. High efficiency photoelectrochemical systems to produce hydrogen directly from water using sunlight as the energy source represent one of the technologies identified by DOE to meet this mission. Reactor modeling and experiments conducted at UH provide strong evidence that direct solar-to-hydrogen conversion efficiency greater than 10% can be expected using photoelectrodes fabricated from low-cost, multijunction (MJ) amorphous silicon solar cells. Solar-to-hydrogen conversion efficiencies as high as 7.8% have been achieved using a 10.3% efficient MJ amorphous silicon solar cell. Higher efficiency can be expected with the use of higher efficiency solar cells, further improvement of the thin film oxidation and reduction catalysts, and optimization of the solar cell for hydrogen production rather than electricity production. Hydrogen and oxygen catalysts developed under this project are very stable, exhibiting no measurable degradation in KOH after over 13,000 hours of operation. Additional research is needed to fully optimize the transparent, conducting coatings which will be needed for large area integrated arrays. To date, the best protection has been afforded by wide bandgap amorphous silicon carbide films.

  13. Multifunctional reduced graphene oxide trigged chemiluminescence resonance energy transfer: Novel signal amplification strategy for photoelectrochemical immunoassay of squamous cell carcinoma antigen.

    PubMed

    Zhang, Yan; Sun, Guoqiang; Yang, Hongmei; Yu, Jinghua; Yan, Mei; Song, Xianrang

    2016-05-15

    Herein, a photoelectrochemical (PEC) immunoassay is constructed for squamous cell carcinoma antigen (SCCA) detection using zinc oxide nanoflower-bismuth sulfide (Bi2S3) composites as photoactive materials and reduced graphene oxide (rGO) as signal labels. Horseradish peroxidase is used to block sites against nonspecific binding, and then participated in luminol-based chemiluminescence (CL) system. The induced CL emission is acted as an inner light source to excite photoactive materials, simplifying the instrument. A novel signal amplification strategy is stem from rGO because of the rGO acts as an energy acceptor, while luminol serves as a donor to rGO, triggering the CL resonance energy transfer phenomenon between luminol and rGO. Thus, the efficient CL emission to photoactive materials decreases. Furthermore, the signal amplification caused by rGO labeled signal antibodies is related to photogenerated electron-hole pairs: perfect matching of energy levels between rGO and Bi2S3 makes rGO a sink to capture photogenerated electrons from Bi2S3; the increased steric hindrance hinders the electron donor to the surface of Bi2S3 for reaction with the photogenerated holes. On the basis of the novel signal amplification strategy, the proposed immunosensor exhibits excellent analytical performance for PEC detection of SCCA, ranging from 0.8 pg mL(-1) to 80 ng mL(-1) with a low detection limit of 0.21 pg mL(-1). Meanwhile, the designed signal amplification strategy provides a general format for future development of PEC assays. PMID:26686924

  14. Photoelectrocatalytic oxidation of glucose at a ruthenium complex modified titanium dioxide electrode promoted by uric acid and ascorbic acid for photoelectrochemical fuel cells

    NASA Astrophysics Data System (ADS)

    Lu, Shuo-Jian; Ji, Shi-Bo; Liu, Jun-Chen; Li, Hong; Li, Wei-Shan

    2015-01-01

    The simultaneous presence of uric acid (UA) and ascorbic acid (AA) is first found to largely promote the photoelectrocatalytic oxidation of glucose (GLU) at an indium-tin oxide (ITO) or TiO2 nanoparticles/ITO electrode modified with [Ru(tatp)3]2+ (tatp = 1,4,8,9-tetra-aza-triphenylene) possessing good redox activity and nanoparticle size distribution. A well-defined electrocatalytic peak for GLU oxidation is shown at 0.265 V (vs. SCE) under approximate physiological conditions upon incorporation of UA and AA. The [Ru(tatp)3]2+/ITO electrode exhibits attractive amperometric oxidation responses towards GLU, UA and AA, while controlled potentiostatically at 0.3 V, 0.7 V and 1.0 V, respectively, indicating high sensitivity and excellent reproducibility. On basis of the photoelectrocatalysis of [Ru(tatp)3]2+/TiO2/ITO anode, a GLU concentration-dependent photoelectrochemical fuel cell vs. SCE is elaborately assembled. The proposed free-enzyme photoelectrochemical fuel cell employing 0.1 M GLU associated with 0.01 M UA and 0.01 M AA as fuel shows open-circuit photovoltage of 0.608 V, short-circuit photocurrent density of 124.5 μA cm-2 and maximum power density of 21.75 μW cm-2 at 0.455 V, fill factor of 0.32 and photoenergy conversion efficiency of 36.65%, respectively.

  15. Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells.

    PubMed

    Vargas-Barbosa, Nella M; Geise, Geoffrey M; Hickner, Michael A; Mallouk, Thomas E

    2014-11-01

    Membranes are important in water-splitting solar cells because they prevent crossover of hydrogen and oxygen. Here, bipolar membranes (BPMs) were tested as separators in water electrolysis cells. Steady-state membrane and solution resistances, electrode overpotentials, and pH gradients were measured at current densities relevant to solar photoelectrolysis. Under forward bias conditions, electrodialysis of phosphate buffer ions creates a pH gradient across a BPM. Under reverse bias, the BPM can maintain a constant buffer pH on both sides of the cell, but a large membrane potential develops. Thus, the BPM does not present a viable solution for electrolysis in buffered electrolytes. However, the membrane potential is minimized when the anode and cathode compartments of the cell contain strongly basic and acidic electrolytes, respectively.

  16. A signal "on" photoelectrochemical biosensor for assay of protein kinase activity and its inhibitor based on graphite-like carbon nitride, Phos-tag and alkaline phosphatase.

    PubMed

    Yin, Huanshun; Sun, Bing; Dong, Linfeng; Li, Bingchen; Zhou, Yunlei; Ai, Shiyun

    2015-02-15

    A highly sensitive and selective photoelectrochemical (PEC) biosensor is fabricated for the detection of protein kinase activity based on visible-light active graphite-like carbon nitride (g-C3N4) and the specific recognition utility of Phos-tag for protein kinase A (PKA)-induced phosphopeptides. For assembling the substrate peptides, g-C3N4 and gold nanoparticles (g-C3N4-AuNPs) complex is synthesized and characterized. When the immobilized peptides on g-C3N4-AuNPs modified ITO electrode are phosphorylated under PKA catalysis, they can be specifically identified and binded with biotin functionalized Phos-tag (Phos-tag-biotin) in the presence of Zn(2+). Then, through the specific interaction between biotin and avidin, avidin functionalized alkaline phosphatase (avidin-ALP) is further assembled to catalyze its substrate of l-ascorbic acid-2-phosphate trisodium salt (AAP) to produce electron donor of ascorbic acid (AA), resulting an increased photocurrent compared with the absence of phosphorylation event. Based on the specific identification effect of Phos-tag, the fabricated biosensor presents excellent selectivity for capturing the phosphorylated serine residues in the substrate peptides. With the good photoactivity of g-C3N4 and ALP-catalyzed signal amplification, the fabricated biosensor presents high sensitivity and low detection limit (0.015 unit/mL, S/N = 3) for PKA. The applicability of this PEC biosensor is further testified by the evaluation of PKA inhibition by HA-1077 with the IC50 value of 1.18μM. This new strategy is also successfully applied to detect the change of PKA activity in cancer cell lysate with and without drug stimulation. Therefore, the developed PEC method has great potential in screening of kinase inhibitors and highly sensitive detection of kinase activity.

  17. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity

    DOEpatents

    Skotheim, T.

    1984-09-28

    There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  18. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity

    DOEpatents

    Skotheim, Terje

    1986-01-01

    There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  19. Photoelectrochemical hydrogen production

    SciTech Connect

    Rocheleau, R.E.; Miller, E.; Zhang, Z.

    1995-09-01

    The large-scale production of hydrogen utilizing energy provided by a renewable source to split water is one of the most ambitious long-term goals of the U.S. Department of Energy`s Hydrogen Program. Photoelectrochemical devices-direct photoconversion systems utilizing a photovoltaic-type structure coated with water-splitting catalysts-represent a promising option to meet this goal. Direct solar-to-chemical conversion efficiencies greater than 7% and photoelectrode lifetimes of up to 30 hours in 1 molar KOH have been demonstrated in our laboratory using low-cost, amorphous-silicon-based photoelectrodes. Loss analysis models indicate that the DOE`s goal of 10% solar-to-chemical conversion can be met with amorphous-silicon-based structures optimized for hydrogen production. In this report, we describe recent progress in the development of thin-film catalytic/protective coatings, improvements in photoelectrode efficiency and stability, and designs for higher efficiency and greater stability.

  20. I-III-VI2 (Copper Chalcopyrite-based) Materials for Use in Hybrid Photovoltaic/Photoelectrochemical Water-Splitting Devices

    NASA Astrophysics Data System (ADS)

    Kaneshiro, Jess Masao Makana

    This project, in an effort to improve upon basic crystalline silicon photovoltaic energy conversion, proposes both an alternative material and an alternative method of solar energy conversion. The sun, responsible for giving us life of all kinds, is capable of giving us more. Photovoltaic energy, derived from the conversion of solar energy to electrical energy, can be a very efficient process. Unfortunately, it is often produced at a location and time where we are unable to use it immediately, necessitating transmission or storage of this converted energy; both imposing energy losses and costs. Furthermore, the typical use of crystalline silicon for this process is hindered by supply and fabrication cost issues. Photoelectrochemical (PEC) water-splitting offers an alternative energy-transport mechanism in the form of evolved hydrogen gas. Untethered by aging power lines and insufficient energy distribution technology, hydrogen gas offers new methods to store and transport converted solar energy to be used in fuel cells or hydrogen combustion engines representing a sustainable, clean and completely carbon-free energy cycle. PEC water-splitting also allows the use of a variety of new semiconductor materials like the I-III-VI2 copper chalcopyrite based material class capable of displacing our reliance on crystalline silicon used to harness the sun's power. Capable of photocurrents as high as 20mA/cm 2, a device utilizing this material demonstrates 4.35% solar-to-hydrogen conversion efficiency. Material durability is also documented, achieving 420 hours of sustained water-splitting representing 4.6 years of operation.

  1. Spectroscopic and photoelectrochemical studies of metal-free dyes for applications in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Mulhern, Kacie Ryan

    In this dissertation, we present a series of novel chalcogenorhodamine dyes bearing phosphonic acids and carboxylic acids for sensitizers of nanocrystalline TiO2 in dye-sensitized solar cells (DSCs). We studied the effect of surface-attachment functionality and aggregation on the persistence, electron transfer reactivity, and overall photoelectrochemical performance of the dyes on TiO2 for DSCs. The dyes were constructed around a 3,6-bis(dimethylamino)chalcogenoxanthylium core and varied in the 9-substituent: 5-carboxythien-2-yl in dyes 1-E (E = O, Se), 2-carboxythien-3-yl in dyes 2-E (E = Se), 5-phosphonothien-2-yl in dyes 3-E (E = O, Se), 4-carboxyphenyl in dyes 4-E (E = O, S), and 4-phosphonophenyl in dyes 5-E (E = O, Se). Monolayers of 1-E, 3-E, 4-E, and 5-E on nanocrystalline TiO2 films consisted of both H-aggregated and non-aggregated dyes, whereas 2-E underwent little or no aggregation upon adsorption. With the exception of 2-E, surface coverages of dyes and the extent of H-aggregation varied minimally with surface-attachment functionality, structure of the 9-aryl group, and identity of the chalcogen heteroatom. Carboxylic acid-functionalized dyes 1-E and 4-E desorbed rapidly and completely from TiO2 into acidified CH3CN, but phosphonic acid-functionalized dyes 3-E and 5-E persisted on TiO2 for days. We used transient absorption spectroscopy to characterize excited-state electron injection from a 1-Se, 2-Se, and 3-Se to TiO2. Injection of electrons from photoexcited dyes into TiO2 yielded the dication radical (1-Se +, 2-Se+, and 3-Se +) and an associated transient absorption at wavelengths shorter than 540 nm, the amplitude of which was proportional to the quantum yield of electron injection (Qinj). Our data reveal the Qinj for H-aggregated 1-Se was approximately 2-fold greater than Q inj for non-aggregated 1-Se and approximately 3-fold greater than Qinj for non-aggregated 2-Se. Additionally, the Qinj from H-aggregated 3-Se was (2.0 +/- 1.3)-fold greater

  2. Routes to Ultrahigh Efficiency Photovoltaic and Photoelectrochemical Devices

    SciTech Connect

    Eisler, Carissa; Lloyd, John; Flowers, Cris; Darbe, Sunita; Warmann, Emily; Verlage, Erik; Fountaine, Kate; Hu, Shu; Lewis, Nathan; Atwater, Harry

    2014-10-15

    We discuss ‘full spectrum’ photovoltaic modules that leverage low-cost III-V compound semiconductor cells, efficient optics and unconventional fabrication/assembly methods, and discuss advances in photoelectrochemical water-splitting with high efficiency.

  3. On the sigmoidal shape of current-voltage curves of photoelectrochemical solar cells

    SciTech Connect

    Mao, D.; Kim, K.J.; Frank, A.J.

    1995-06-01

    Current-voltage (J-V) curves of n-GaAs/KOH(aq)-Se{sub 2}{sup 2{minus}}/Se{sup 2{minus}} and n-Si/acetone-LiClO{sub 4}-Fc{sup +/0} (ferrocenium ion/ferrocene) solar cells exhibit sigmoidal shapes near the open-circuit potential. J-V and flatband potential measurements indicate that the deviation of the J-V curves from the ideal square-like shape to S shape is due to the light-induced displacement of the bandedges. Analytical expression describing the dependence of light-induced bandedge shifts on the anodic photocurrent, the density of surface states, and the interfacial charge-transfer velocity are derived and verified experimentally. Application of the expressions to J-V data yields quantitative information on the kinetics of interfacial charge transfer.

  4. Brown seaweed pigment as a dye source for photoelectrochemical solar cells.

    PubMed

    Calogero, Giuseppe; Citro, Ilaria; Di Marco, Gaetano; Armeli Minicante, Simona; Morabito, Marina; Genovese, Giuseppa

    2014-01-01

    Chlorophylls based-dyes obtained from seaweeds represent attractive alternatives to the expensive and polluting pyridil based Ru complexes because of their abundance in nature. Another important characteristic is that the algae do not subtract either cropland or agricultural water, therefore do not conflict with agro-food sector. This pigment shows a typical intense absorption in the UV/blue (Soret band) and a less intense band in the red/near IR (Q band) spectral regions and for these reasons appear very promising as sensitizer dyes for DSSC. In the present study, we utilized chlorophylls from samples of the brown alga Undaria pinnatifida as sensitizer in DSSCs. The dye, extracted by frozen seaweeds and used without any chemical purification, showed a very good fill factor (0.69). Even the photelectrochemical parameters if compared with the existent literature are very interesting.

  5. Brown seaweed pigment as a dye source for photoelectrochemical solar cells

    NASA Astrophysics Data System (ADS)

    Calogero, Giuseppe; Citro, Ilaria; Di Marco, Gaetano; Armeli Minicante, Simona; Morabito, Marina; Genovese, Giuseppa

    2014-01-01

    Chlorophylls based-dyes obtained from seaweeds represent attractive alternatives to the expensive and polluting pyridil based Ru complexes because of their abundance in nature. Another important characteristic is that the algae do not subtract either cropland or agricultural water, therefore do not conflict with agro-food sector. This pigment shows a typical intense absorption in the UV/blue (Soret band) and a less intense band in the red/near IR (Q band) spectral regions and for these reasons appear very promising as sensitizer dyes for DSSC. In the present study, we utilized chlorophylls from samples of the brown alga Undaria pinnatifida as sensitizer in DSSCs. The dye, extracted by frozen seaweeds and used without any chemical purification, showed a very good fill factor (0.69). Even the photelectrochemical parameters if compared with the existent literature are very interesting.

  6. Photoelectrochemical Hydrogen Production

    SciTech Connect

    Hu, Jian

    2013-12-23

    The objectives of this project, covering two phases and an additional extension phase, were the development of thin film-based hybrid photovoltaic (PV)/photoelectrochemical (PEC) devices for solar-powered water splitting. The hybrid device, comprising a low-cost photoactive material integrated with amorphous silicon (a-Si:H or a-Si in short)-based solar cells as a driver, should be able to produce hydrogen with a 5% solar-to-hydrogen conversion efficiency (STH) and be durable for at least 500 hours. Three thin film material classes were studied and developed under this program: silicon-based compounds, copper chalcopyrite-based compounds, and metal oxides. With the silicon-based compounds, more specifically the amorphous silicon carbide (a-SiC), we achieved a STH efficiency of 3.7% when the photoelectrode was coupled to an a-Si tandem solar cell, and a STH efficiency of 6.1% when using a crystalline Si PV driver. The hybrid PV/a-SiC device tested under a current bias of -3~4 mA/cm{sup 2}, exhibited a durability of up to ~800 hours in 0.25 M H{sub 2}SO{sub 4} electrolyte. Other than the PV driver, the most critical element affecting the photocurrent (and hence the STH efficiency) of the hybrid PV/a-SiC device was the surface energetics at the a-SiC/electrolyte interface. Without surface modification, the photocurrent of the hybrid PEC device was ~1 mA/cm{sup 2} or lower due to a surface barrier that limits the extraction of photogenerated carriers. We conducted an extensive search for suitable surface modification techniques/materials, of which the deposition of low work function metal nanoparticles was the most successful. Metal nanoparticles of ruthenium (Ru), tungsten (W) or titanium (Ti) led to an anodic shift in the onset potential. We have also been able to develop hybrid devices of various configurations in a monolithic fashion and optimized the current matching via altering the energy bandgap and thickness of each constituent cell. As a result, the short

  7. Photo-enhanced salt-water splitting using orthorhombic Ag8SnS6 photoelectrodes in photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Cheng, Kong-Wei; Tsai, Wei-Tseng; Wu, Yu-Hsuan

    2016-06-01

    Orthorhombic Ag8SnS6 photoelectrodes are prepared on various substrates via reactive sulfurization using the radio-frequency magnetron sputtering of silver-tin metal precursors. Evaluations of the photoelectrochemical performances of Ag8SnS6 photoelectrodes with various levels of silver content are carried out in various aqueous solutions. X-ray diffraction patterns and Hall measurements of samples after a three-stage sulfurization process show that all samples are the pure orthorhombic Ag8SnS6 phase with n-type conductivity. The energy band gaps, carrier concentrations, and mobilities of samples on glass substrates are 1.31-1.33 eV, 7.07 × 1011-8.52 × 1012 cm-3, and 74.9-368 cm2 V-1 s-1, respectively, depending on the [Ag]/[Ag+Sn] molar ratio in samples. The highest photoelectrochemical performances of orthorhombic Ag8SnS6 photoelectrodes in aqueous 0.35 M Na2S + 0.25 M K2SO3 and 0.5 M NaCl solutions are respectively 2.09 and 2.5 mA cm-2 at an applied voltages of 0.9 and 1.23 V vs. a reversible hydrogen electrode under light irradiation with a light intensity of 100 mW cm-2 from a 300-W Xe lamp.

  8. A sensitive photoelectrochemical biosensor for AFP detection based on ZnO inverse opal electrodes with signal amplification of CdS-QDs.

    PubMed

    Xu, Ru; Jiang, Yandong; Xia, Lei; Zhang, Tianxiang; Xu, Lin; Zhang, Shuang; Liu, Dali; Song, Hongwei

    2015-12-15

    In this work, ZnO inverse opals structure (IOs) based photoelectrochemical (PEC) electrode was fabricated for alpha-fetoprotein (AFP) detection. Then, the uniform CdS quantum dots (QDs) were hydrothermally synthesized, which allowed the binding of AFP and glucose oxidase (GOD) on CdS QDs, forming the AFP-CdS-GOD composite. The competitive immunosensor of AFP and the AFP-CdS-GOD composite with anti-AFP antibodies (Ab) immobilized on FTO (fluorine-doped tin oxide) /ZnO IOs electrode was successfully applied to the detection of AFP. GOD could catalyze glucose to produce hydrogen peroxide (H2O2) acting as an electron donor to scavenge photogenerated holes in the valence band of CdS QDs, reducing the recombination of electrons and holes of CdS QDs. Also the effective energy level matching between the conduction bands of CdS QDs and ZnO widened the range of light absorption, allowing for electron injection from excited CdS QDs to ZnO upon visible light irradiation, which enhanced the photocurrent. The results show that the immunosensor of AFP possesses a large linear detection range of 0.1-500 ng/ml with a detection limit of 0.01 ng/ml. It also exhibits excellent anti-interference property and acceptable stability. This work provides a promising method for achieving excellent photoelectrochemical biosensor detection of other proteins. PMID:26164013

  9. A sensitive photoelectrochemical biosensor for AFP detection based on ZnO inverse opal electrodes with signal amplification of CdS-QDs.

    PubMed

    Xu, Ru; Jiang, Yandong; Xia, Lei; Zhang, Tianxiang; Xu, Lin; Zhang, Shuang; Liu, Dali; Song, Hongwei

    2015-12-15

    In this work, ZnO inverse opals structure (IOs) based photoelectrochemical (PEC) electrode was fabricated for alpha-fetoprotein (AFP) detection. Then, the uniform CdS quantum dots (QDs) were hydrothermally synthesized, which allowed the binding of AFP and glucose oxidase (GOD) on CdS QDs, forming the AFP-CdS-GOD composite. The competitive immunosensor of AFP and the AFP-CdS-GOD composite with anti-AFP antibodies (Ab) immobilized on FTO (fluorine-doped tin oxide) /ZnO IOs electrode was successfully applied to the detection of AFP. GOD could catalyze glucose to produce hydrogen peroxide (H2O2) acting as an electron donor to scavenge photogenerated holes in the valence band of CdS QDs, reducing the recombination of electrons and holes of CdS QDs. Also the effective energy level matching between the conduction bands of CdS QDs and ZnO widened the range of light absorption, allowing for electron injection from excited CdS QDs to ZnO upon visible light irradiation, which enhanced the photocurrent. The results show that the immunosensor of AFP possesses a large linear detection range of 0.1-500 ng/ml with a detection limit of 0.01 ng/ml. It also exhibits excellent anti-interference property and acceptable stability. This work provides a promising method for achieving excellent photoelectrochemical biosensor detection of other proteins.

  10. Enhancing the photoelectrochemical water splitting characteristics of titanium and tungsten oxide based materials via doping and sensitization

    NASA Astrophysics Data System (ADS)

    Gakhar, Ruchi

    To better utilize solar energy for clean energy production, efforts are needed to overcome the natural diurnal variation and the diffuse nature of sunlight. Photoelectrochemical (PEC) hydrogen generation by water splitting is a promising approach to harvest solar energy. Hydrogen gas is a clean and high energy capacity fuel. However, the solar-to-hydrogen conversion efficiency is determined mainly by the properties of the materials employed as photoanodes. Improving the power-conversion efficiency of PEC water splitting requires the design of inexpensive and efficient photoanodes that have strong visible light absorption, fast charge separation, and lower charge recombination rate. In the present study, PEC characteristics of various semiconducting photoelectrodes such as TiO2, WO3 and CuWO4 were investigated. Due to the inherent wide gap, such metal oxides absorb only ultraviolet radiation. Since ultraviolet radiation only composes of 4% of the sun's spectrum, the wide band gap results in lower charge collection and efficiency. Thusto improve optical absorption and charge separation, it is necessary to modify the band gap with low band gap materials.The two approaches followed for modification of band gap are doping and sensitization. Here, TiO2 and WO3 based photoanodes were sensitized with ternary quatum dots, while doping was the primary method utilized to investigate the modification of the band gap of CuWO4. The first part of this dissertation reports the synthesis of ternary quantum dot - sensitized titania nanotube array photoelectrodes. Ternary quantum dots with varying band gaps and composition (MnCdSe, ZnCdSe and CdSSe) were tethered to the surface of TiO2 nanotubes using succcessive ionic layer adsorption and reaction (SILAR) technique. The stoichiometry of ternary quantum dots was estimated to beMn0.095Cd0.95Se, Zn0.16Cd0.84Se and CdS0.54Se0.46. The effect of varying number of sensitization cycles and annealing temperature on optical and

  11. Ratiometric fluorescence, electrochemiluminescence, and photoelectrochemical chemo/biosensing based on semiconductor quantum dots

    NASA Astrophysics Data System (ADS)

    Wu, Peng; Hou, Xiandeng; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-04-01

    Ratiometric fluorescent sensors, which can provide built-in self-calibration for correction of a variety of analyte-independent factors, have attracted particular attention for analytical sensing and optical imaging with the potential to provide a precise and quantitative analysis. A wide variety of ratiometric sensing probes using small fluorescent molecules have been developed. Compared with organic dyes, exploiting semiconductor quantum dots (QDs) in ratiometric fluorescence sensing is even more intriguing, owing to their unique optical and photophysical properties that offer significant advantages over organic dyes. In this review, the main photophysical mechanism for generating dual-emission from QDs for ratiometry is discussed and categorized in detail. Typically, dual-emission can be obtained either with energy transfer from QDs to dyes or with independent dual fluorophores of QDs and dye/QDs. The recent discovery of intrinsic dual-emission from Mn-doped QDs offers new opportunities for ratiometric sensing. Particularly, the signal transduction of QDs is not restricted to fluorescence, and electrochemiluminescence and photoelectrochemistry from QDs are also promising for sensing, which can be made ratiometric for correction of interferences typically encountered in electrochemistry. All these unique photophysical properties of QDs lead to a new avenue of ratiometry, and the recent progress in this area is addressed and summarized here. Several interesting applications of QD-based ratiometry are presented for the determination of metal ions, temperature, and biomolecules, with specific emphasis on the design principles and photophysical mechanisms of these probes.

  12. An ultrasensitive photoelectrochemical nucleic acid biosensor

    PubMed Central

    Gao, Zhiqiang; Tansil, Natalia C.

    2005-01-01

    A simple and ultrasensitive procedure for non-labeling detection of nucleic acids is described in this study. It is based on the photoelectrochemical detection of target nucleic acids by forming a nucleic acid/photoreporter adduct layer on an ITO electrode. The target nucleic acids were hybridized with immobilized oligonucleotide capture probes on the ITO electrode. A subsequent binding of a photoreporter—a photoactive threading bis-intercalator consisting of two N,N′-bis(3-propyl-imidazole)-1,4,5,8-naphthalene diimides (PIND) linked by a Ru(bpy)22+ (bpy = 2,2′-bipyridine) complex (PIND–Ru–PIND)—allowed for photoelectrochemical detection of the target nucleic acids. The extremely low dissociation rate of the adduct and the highly reversible photoelectrochemical response under visible light illumination (490 nm) make it possible to conduct nucleic acid detection, with a sensitivity enhancement of four orders of magnitude over voltammetry. These results demonstrate for the first time the potential of photoelectrochemical biosensors for PCR-free ultrasensitive detection of nucleic acids. PMID:16061935

  13. Physical properties of hematite α-Fe2O3 thin films: application to photoelectrochemical solar cells

    NASA Astrophysics Data System (ADS)

    Shinde, S. S.; Bansode, R. A.; Bhosale, C. H.; Rajpure, K. Y.

    2011-01-01

    The physical properties and photoelectrochemical characterization of aluminium doped hematite α-Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron (III) oxide thin films synthesized by a spray pyrolysis technique reveals an oxygen deficiency, and the oxide exhibits n-type conductivity confirmed by anodic photocurrent generation. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The deposited iron oxide thin films show the single hematite phase with polycrystalline rhombohedral crystal structure with crystallite size 20-40 nm. Optical analysis enabled to point out the increase in direct band-gap energy from 2.2 to 2.25 eV with doping concentration which is attributed to a blue shift. The dielectric constant and dielectric loss are studied as a function of frequency. To understand the conduction mechanism in the films, AC conductivity is measured. The conduction occurs by small polaron hopping through mixed valences Fe2+/3+ with an electron mobility 300 K of 1.08 cm2/(V·s). The α-Fe2O3 exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as a photoanode for various electrolytes using white light to obtain I — V characteristics. The Al-doped hematite exhibited a higher photocurrent response when compared with undoped films achieving a power conversion efficiency of 2.37% at 10 at % Al:Fe2O3 thin films along with fill factor 0.38 in NaOH electrolyte. The flat band potential Vfb (-0.87 VSCE) is determined by extrapolating the linear part to C-2 = 0 and the slope of the Mott-Schottky plot.

  14. Higher-efficiency photoelectrochemical electrodes of titanium dioxide-based nanoarrays sensitized simultaneously with plasmonic silver nanoparticles and multiple metal sulfides photosensitizers

    NASA Astrophysics Data System (ADS)

    Guo, Keying; Liu, Zhifeng; Han, Jianhua; Zhang, Xueqi; Li, Yajun; Hong, Tiantian; Zhou, Cailou

    2015-07-01

    This paper describes a novel design of high-efficiency photoelectrochemical water splitting electrode, i.e., ordered TiO2 nanorod arrays (NRs) sensitized simultaneously with noble metal (Ag), binary metal sulfides (Ag2S) and ternary metal sulfides (Ag3CuS2) multiple photosensitizers for the first time. The TiO2/Ag/Ag2S/Ag3CuS2 NRs heterostructure is successfully synthesized through successive ion layer adsorption and reaction (SILAR) and a simple ion-exchange process based on ionic reaction mechanism. On the basis of an optimal quantity of Ag, Ag2S and Ag3CuS2 nanoparticles, such TiO2/Ag/Ag2S/Ag3CuS2 NRs exhibit a higher photoelectrochemical activity ever reported for TiO2-based nanoarrays in PEC water splitting, the photocurrent density is up to 9.82 mA cm-2 at 0.47 V versus Ag/AgCl, respectively. This novel architecture is able to increase electron collection efficiency and suppress carrier recombination via (i) a higher efficiency of light-harvesting through these multiple photosensitizers (Ag, Ag2S and Ag3CuS2); (ii) the efficient separation of photo-induced electrons and holes due to the direct electrical pathways; (iii) the surface plasmon resonance (SPR) effect of Ag nanoparticles, which enhances the efficient charge separation and high carrier mobility. This work is useful to explore feasible routes to further enhance the performance of oxide semiconductors for PEC water splitting to produce clean H2 energy.

  15. Cadmium Sulphide-Reduced Graphene Oxide-Modified Photoelectrode-Based Photoelectrochemical Sensing Platform for Copper(II) Ions

    PubMed Central

    Ibrahim, I; Lim, H. N; Huang, N. M; Pandikumar, A

    2016-01-01

    A photoelectrochemical (PEC) sensor with excellent sensitivity and detection toward copper (II) ions (Cu2+) was developed using a cadmium sulphide-reduced graphene oxide (CdS-rGO) nanocomposite on an indium tin oxide (ITO) surface, with triethanolamine (TEA) used as the sacrificial electron donor. The CdS nanoparticles were initially synthesized via the aerosol-assisted chemical vapor deposition (AACVD) method using cadmium acetate and thiourea as the precursors to Cd2+ and S2-, respectively. Graphene oxide (GO) was then dip-coated onto the CdS electrode and sintered under an argon gas flow (50 mL/min) for the reduction process. The nanostructured CdS was adhered securely to the ITO by a continuous network of rGO that also acted as an avenue to intensify the transfer of electrons from the conduction band of CdS. The photoelectrochemical results indicated that the ITO/CdS-rGO photoelectrode could facilitate broad UV-visible light absorption, which would lead to a higher and steady-state photocurrent response in the presence of TEA in 0.1 M KCl. The photocurrent decreased with an increase in the concentration of Cu2+ ions. The photoelectrode response for Cu2+ ion detection had a linear range of 0.5–120 μM, with a limit of detection (LoD) of 16 nM. The proposed PEC sensor displayed ultra-sensitivity and good selectivity toward Cu2+ ion detection. PMID:27176635

  16. Cadmium Sulphide-Reduced Graphene Oxide-Modified Photoelectrode-Based Photoelectrochemical Sensing Platform for Copper(II) Ions.

    PubMed

    Ibrahim, I; Lim, H N; Huang, N M; Pandikumar, A

    2016-01-01

    A photoelectrochemical (PEC) sensor with excellent sensitivity and detection toward copper (II) ions (Cu2+) was developed using a cadmium sulphide-reduced graphene oxide (CdS-rGO) nanocomposite on an indium tin oxide (ITO) surface, with triethanolamine (TEA) used as the sacrificial electron donor. The CdS nanoparticles were initially synthesized via the aerosol-assisted chemical vapor deposition (AACVD) method using cadmium acetate and thiourea as the precursors to Cd2+ and S2-, respectively. Graphene oxide (GO) was then dip-coated onto the CdS electrode and sintered under an argon gas flow (50 mL/min) for the reduction process. The nanostructured CdS was adhered securely to the ITO by a continuous network of rGO that also acted as an avenue to intensify the transfer of electrons from the conduction band of CdS. The photoelectrochemical results indicated that the ITO/CdS-rGO photoelectrode could facilitate broad UV-visible light absorption, which would lead to a higher and steady-state photocurrent response in the presence of TEA in 0.1 M KCl. The photocurrent decreased with an increase in the concentration of Cu2+ ions. The photoelectrode response for Cu2+ ion detection had a linear range of 0.5-120 μM, with a limit of detection (LoD) of 16 nM. The proposed PEC sensor displayed ultra-sensitivity and good selectivity toward Cu2+ ion detection. PMID:27176635

  17. A novel method to synthesize highly photoactive Cu2O microcrystalline films for use in photoelectrochemical cells.

    PubMed

    Li, Changli; Li, Yanbo; Delaunay, Jean-Jacques

    2014-01-01

    Large-scale and high-quality Cu2O microcrystalline films with high photoactivity are synthesized using a novel and low-cost method. The enhanced photoactivity is achieved through the formation of Cu2O microcrystalline films having well-defined crystal facets and porous structure. Cu2O microcrystalline films are fabricated by decomposing previously synthesized Cu(OH)2 nanowires on a Cu foil under a vacuum. Subsequent crystal growth during the annealing process is driven by outward diffusion of Cu ions and oxidation. Crystal growth induces coalescence of the nanowires and results in the formation of Cu2O microcrystals enclosed by four {111} facets. Photoelectrochemical evaluation of the annealed samples performed under chopped simulated AM 1.5G illumination reveals that the sample annealed at 500 °C for 2 h exhibited the highest photocurrent of 4.07 mA/cm(2) at 0 V/RHE. This large photocurrent is ascribed to a high carrier density (~1.36 × 10(18) cm(-3)) and a low carrier transfer resistance in electrolyte, as evidenced by electrochemical impedance spectroscopy. The obtained low-cost Cu2O microcrystalline film (2 h) may serve as an excellent solar absorber and carrier provider for use in photovoltaics and artificial photosynthesis. PMID:24299015

  18. Correlation of electrical and physical properties of photoanode with hydrogen evolution in enzymatic photo-electrochemical cell

    NASA Astrophysics Data System (ADS)

    Bae, Sanghyun; Kang, Junwon; Shim, Eunjung; Yoon, Jaekyung; Joo, Hyunku

    2008-05-01

    In this study, the electrical and physical properties, including the current density, open-circuit voltage, morphology and crystalline structure, of an anodized TiO2 electrode on a titanium foil are correlated with the hydrogen production rate in an enzymatic photo-electrochemical system. The effect of light intensity at ca. 74 and ca. 146 mW cm-2 on the properties is also examined. Anodizing (20 V; bath temperature 5 °C; anodizing time 45 min) and subsequent annealing (350-850 °C for 5 h) of the Ti foils in an O2 atmosphere led to the formation of a tube-shaped, or a compact layered, TiO2 film on the Ti substrate depending on the annealing temperature. The annealing temperature has a similar effect on the properties of the sample and the hydrogen evolution rate. The generated electrical value, the chronoamperometry (CA), is +13 to -229 and +13 to -247 μA for light intensities of ca. 74 and ca. 146 mW cm-2, while the corresponding open-circuit voltage (OCV) is in the range of -41 to -687 and -144 to 738 mV, respectively. In the absence of light (dark), the CA is 13-29 μA and the OCV is +258 to -126 mW cm-2. The trend in the electrical properties for the different samples is well matched with the rate of hydrogen evolution. The samples with higher activities (450, 550, and 650 °C) have similar X-ray diffraction (XRD) patterns, which clearly indicates that the samples showing the highest evolution rate are composed of both anatase and rutile, while those showing a lower evolution rate are made of either anatase or rutile. Increasing the intensity of the irradiated light causes a remarkable enhancement in the rate of hydrogen production from 71 to 153 μmol h-1 cm-2.

  19. Semiconducting materials for photoelectrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Sivula, Kevin; van de Krol, Roel

    2016-02-01

    To achieve a sustainable society with an energy mix primarily based on solar energy, we need methods of storing energy from sunlight as chemical fuels. Photoelectrochemical (PEC) devices offer the promise of solar fuel production through artificial photosynthesis. Although the idea of a carbon-neutral energy economy powered by such ‘artificial leaves’ is intriguing, viable PEC energy conversion on a global scale requires the development of devices that are highly efficient, stable and simple in design. In this Review, recently developed semiconductor materials for the direct conversion of light into fuels are scrutinized with respect to their atomic constitution, electronic structure and potential for practical performance as photoelectrodes in PEC cells. The processes of light absorption, charge separation and transport, and suitable energetics for energy conversion in PEC devices are emphasized. Both the advantageous and unfavourable aspects of multinary oxides, oxynitrides, chalcogenides, classic semiconductors and carbon-based semiconductors are critically considered on the basis of their experimentally demonstrated performance and predicted properties.

  20. Dynamics of Electron Injection in SnO2/TiO2 Core/Shell Electrodes for Water-Splitting Dye-Sensitized Photoelectrochemical Cells.

    PubMed

    McCool, Nicholas S; Swierk, John R; Nemes, Coleen T; Schmuttenmaer, Charles A; Mallouk, Thomas E

    2016-08-01

    Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) rely on photoinduced charge separation at a dye/semiconductor interface to supply electrons and holes for water splitting. To improve the efficiency of charge separation and reduce charge recombination in these devices, it is possible to use core/shell structures in which photoinduced electron transfer occurs stepwise through a series of progressively more positive acceptor states. Here, we use steady-state emission studies and time-resolved terahertz spectroscopy to follow the dynamics of electron injection from a photoexcited ruthenium polypyridyl dye as a function of the TiO2 shell thickness on SnO2 nanoparticles. Electron injection proceeds directly into the SnO2 core when the thickness of the TiO2 shell is less than 5 Å. For thicker shells, electrons are injected into the TiO2 shell and trapped, and are then released into the SnO2 core on a time scale of hundreds of picoseconds. As the TiO2 shell increases in thickness, the probability of electron trapping in nonmobile states within the shell increases. Conduction band electrons in the TiO2 shell and the SnO2 core can be differentiated on the basis of their mobility. These observations help explain the observation of an optimum shell thickness for core/shell water-splitting electrodes.

  1. "Signal-on" photoelectrochemical biosensor for sensitive detection of human T-Cell lymphotropic virus type II DNA: dual signal amplification strategy integrating enzymatic amplification with terminal deoxynucleotidyl transferase-mediated extension.

    PubMed

    Shen, Qingming; Han, Li; Fan, Gaochao; Zhang, Jian-Rong; Jiang, Liping; Zhu, Jun-Jie

    2015-01-01

    A novel "signal-on" photoelectrochemical (PEC) biosensor for sensitive detection of human T-cell lymphotropic virus type II (HTLV-II) DNA was developed on the basis of enzymatic amplification coupled with terminal deoxynucleotidyl transferase (TdT)-mediated extension strategy. The intensity of the photocurrent signal was proportional to the concentration of the HTLV-II DNA-target DNA (tDNA) by dual signal amplification. In this protocol, GR-CdS:Mn/ZnS nanocomposites were used as photoelectric conversion material, while pDNA was used as the tDNA recognizing unit. Moreover, the TdT-mediated extension and the enzymatic signal amplification technique were used to enhance the sensitivity of detection. Using this novel dual signal amplification strategy, the prototype of PEC DNA sensor can detect as low as ∼0.033 fM of HTLV-II DNA with a linear range of 0.1-5000 fM, with excellent differentiation ability even for single-base mismatches. This PEC DNA assay opens a promising platform to detect various DNA targets at ultralow levels for early diagnoses of different diseases. PMID:25871300

  2. Matrix-assisted laser desorption/ionization mass spectrometric analysis of poly(3,4-ethylenedioxythiophene) in solid-state dye-sensitized solar cells: comparison of in situ photoelectrochemical polymerization in aqueous micellar and organic media.

    PubMed

    Zhang, Jinbao; Ellis, Hanna; Yang, Lei; Johansson, Erik M J; Boschloo, Gerrit; Vlachopoulos, Nick; Hagfeldt, Anders; Bergquist, Jonas; Shevchenko, Denys

    2015-04-01

    Solid-state dye-sensitized solar cells (sDSCs) are devoid of such issues as electrolyte evaporation or leakage and electrode corrosion, which are typical for traditional liquid electrolyte-based DSCs. Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most popular and efficient p-type conducting polymers that are used in sDSCs as a solid-state hole-transporting material. The most convenient way to deposit this insoluble polymer into the dye-sensitized mesoporous working electrode is in situ photoelectrochemical polymerization. Apparently, the structure and the physicochemical properties of the generated conducting polymer, which determine the photovoltaic performance of the corresponding solar cell, can be significantly affected by the preparation conditions. Therefore, a simple and fast analytical method that can reveal information on polymer chain length, possible chemical modifications, and impurities is strongly required for the rapid development of efficient solar energy-converting devices. In this contribution, we applied matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) for the analysis of PEDOT directly on sDSCs. It was found that the PEDOT generated in aqueous micellar medium possesses relatively shorter polymeric chains than the PEDOT deposited from an organic medium. Furthermore, the micellar electrolyte promotes a transformation of one of the thiophene terminal units to thiophenone. The introduction of a carbonyl group into the PEDOT molecule impedes the growth of the polymer chain and reduces the conductivity of the final polymer film. Both the simplicity of sample preparation (only application of the organic matrix onto the solar cell is needed) and the rapidity of analysis hold the promise of making MALDI MS an essential tool for the physicochemical characterization of conducting polymer-based sDSCs.

  3. A versatile immobilization-free photoelectrochemical biosensor for ultrasensitive detection of cancer biomarker based on enzyme-free cascaded quadratic amplification strategy.

    PubMed

    Ge, Lei; Wang, Wenxiao; Hou, Ting; Li, Feng

    2016-03-15

    In this work, an ultrasensitive immobilization-free photoelectrochemical (PEC) biosensor was successfully developed for the first time based on a novel enzyme-free cascaded quadratic signal amplification strategy. This rationally designed homogeneous dual amplification strategy consists of a target-analog recycling circuit based on catalytic hairpin assembly (CHA) and a hybridization chain reaction (HCR) mediated amplification circuit. In the presence of carcinoembryonic antigen (CEA), a proof-of-concept target, target-analog is released to trigger the upstream CHA recycling circuit. The generated dsDNA complexes from CHA recycling could further induce the downstream HCR amplification, leading to the formation of numerous hemin/G-quadruplex DNAzymes. This would accordingly stimulate the biocatalytic precipitation of 4-chloro-1-naphthol, inducing a distinct decrease in the photocurrent signal due to the formed insoluble/insulating products on electrode surface. Under the optimal conditions, this PEC biosensor achieved ultrasensitive detection of CEA down to the atto-gram level. The introduction of this aptamer-based cascaded quadratic amplification strategy not only remarkably improves the selectivity and sensitivity of CEA assay, but also allows the ultrasensitive detection of other proteins by designing specific aptamers, providing a universal, isothermal and label-free PEC biosensing platform for ultrasensitive detection of different kinds of cancer biomarkers and holding a great potential for early-diagnosis of cancer.

  4. Photoelectrochemical Hydrogen Production - Final Report

    SciTech Connect

    Miller, E.L.; Marsen, B.; Paluselli, D.; Rocheleau, R.

    2004-11-17

    The scope of this photoelectrochemical hydrogen research project is defined by multijunction photoelectrode concepts for solar-powered water splitting, with the goal of efficient, stable, and economic operation. From an initial selection of several planar photoelectrode designs, the Hybrid Photoelectrode (HPE) has been identified as the most promising candidate technology. This photoelectrode consists of a photoelectrochemical (PEC) junction and a solid-state photovoltaic (PV) junction. Immersed in aqueous electrolyte and exposed to sunlight, these two junctions provide the necessary voltage to split water into hydrogen and oxygen gas. The efficiency of the conversion process is determined by the performance of the PEC- and the PV-junctions and on their spectral match. Based on their stability and cost effectiveness, iron oxide (Fe2O3) and tungsten oxide (WO3) films have been studied and developed as candidate semiconductor materials for the PEC junction (photoanode). High-temperature synthesis methods, as reported for some high-performance metal oxides, have been found incompatible with multijunction device fabrication. A low-temperature reactive sputtering process has been developed instead. In the parameter space investigated so far, the optoelectronic properties of WO3 films were superior to those of Fe2O3 films, which showed high recombination of photo-generated carriers. For the PV-junction, amorphous-silicon-based multijunction devices have been studied. Tandem junctions were preferred over triple junctions for better stability and spectral matching with the PEC junction. Based on a tandem a-SiGe/a-SiGe device and a tungsten trioxide film, a prototype hybrid photoelectrode has been demonstrated at 0.7% solar-to-hydrogen (STH) conversion efficiency. The PEC junction performance has been identified as the most critical element for higher-efficiency devices. Research into sputter-deposited tungsten trioxide films has yielded samples with higher photocurrents of

  5. Design of two electrode system for detection of antioxidant capacity with photoelectrochemical platform.

    PubMed

    Han, Dongxue; Ma, Weiguang; Wang, Lingnan; Ni, Shuang; Zhang, Nan; Wang, Wei; Dong, Xiandui; Niu, Li

    2016-01-15

    Recently, a flow photoelectrochemical cell has been first developed and applied to assay global antioxidant capacity in our group. Yet, shortcomings of liquid reference electrode such as sample contaminations from the leaking of the reference solution, mechanically fragile, temperature and light sensitivity, etc. are significant restrictions for integration and miniaturization of photoelectrochemical sensing instruments, which have greatly limited their practical applications. Bearing these problems, in this work a novel two electrode flow photoelectron-chemical system (two-EPCS) has been developed for detection of antioxidant capacity. It is noteworthy that the electrochemical modulation-free mode (detection at the potential of 0.0V) is performed, which has greatly simplified the analysis process and will result in significant simplifications of the instrument integrations. During the sample analysis, both standard antioxidants and commercial beverages were detected. Results evaluated from the two-EPCS are well agreed with those of the traditional three-EPCS at low potentials. By unloading of the reference electrode, it is of great convenience to design a novel photoelectrochemical microfluidic chip based on the two-EPCS, which has also been successfully applied for antioxidant capacity assay. It is satisfactory that comparable detection concentration range and sensitivity were accomplished by applying the microfluidic chip technique. Moreover, the two-EPCS is verified to be a universal platform which does not depend on selected optoelectronic materials but pervasive for general photocatalysts. Such a two-EPCS should be considered as a feasible alternative to the three-EPCS, which will become a promising candidate for industrial and commercial photoelectrochemical sensing instrument integrations in the future. PMID:26363494

  6. Design of two electrode system for detection of antioxidant capacity with photoelectrochemical platform.

    PubMed

    Han, Dongxue; Ma, Weiguang; Wang, Lingnan; Ni, Shuang; Zhang, Nan; Wang, Wei; Dong, Xiandui; Niu, Li

    2016-01-15

    Recently, a flow photoelectrochemical cell has been first developed and applied to assay global antioxidant capacity in our group. Yet, shortcomings of liquid reference electrode such as sample contaminations from the leaking of the reference solution, mechanically fragile, temperature and light sensitivity, etc. are significant restrictions for integration and miniaturization of photoelectrochemical sensing instruments, which have greatly limited their practical applications. Bearing these problems, in this work a novel two electrode flow photoelectron-chemical system (two-EPCS) has been developed for detection of antioxidant capacity. It is noteworthy that the electrochemical modulation-free mode (detection at the potential of 0.0V) is performed, which has greatly simplified the analysis process and will result in significant simplifications of the instrument integrations. During the sample analysis, both standard antioxidants and commercial beverages were detected. Results evaluated from the two-EPCS are well agreed with those of the traditional three-EPCS at low potentials. By unloading of the reference electrode, it is of great convenience to design a novel photoelectrochemical microfluidic chip based on the two-EPCS, which has also been successfully applied for antioxidant capacity assay. It is satisfactory that comparable detection concentration range and sensitivity were accomplished by applying the microfluidic chip technique. Moreover, the two-EPCS is verified to be a universal platform which does not depend on selected optoelectronic materials but pervasive for general photocatalysts. Such a two-EPCS should be considered as a feasible alternative to the three-EPCS, which will become a promising candidate for industrial and commercial photoelectrochemical sensing instrument integrations in the future.

  7. Ag nanoclusters could efficiently quench the photoresponse of CdS quantum dots for novel energy transfer-based photoelectrochemical bioanalysis.

    PubMed

    Zhang, Ling; Sun, Yue; Liang, Yan-Yu; He, Jian-Ping; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-11-15

    Herein the influence of ultrasmall Ag nanoclusters (Ag NCs) against CdS quantum dots (QDs) in a photoelectrochemical (PEC) nanosystem was exploited for the first time, based on which a novel PEC bioanalysis was successfully developed via the efficient quenching effect of Ag NCs against the CdS QDs. In a model system, DNA assay was achieved by using molecular beacon (MB) probes anchored on a CdS QDs modified electrode, and the MB probes contain two segments that can hybridize with both target DNA sequence and the label of DNA encapsulated Ag NCs. After the MB probe was unfolded by the target DNA sequence, the labels of oligonucleotide encapsulated Ag NCs would be brought in close proximity to the CdS QDs electrode surface, and efficient photocurrent quenching of QDs could be resulted from an energy transfer process that originated from NCs. Thus, by monitoring the attenuation in the photocurrent signal, an elegant and sensitive PEC DNA bioanalysis could be accomplished. The developed biosensor displayed a linear range from 1.0pM to 10nM and the detection limit was experimentally found to be of 0.3pM. This work presents a feasible signaling principle that could act as a common basis for general PEC bioanalysis development. PMID:27315518

  8. Visible light photoelectrochemical sensor for ultrasensitive determination of dopamine based on synergistic effect of graphene quantum dots and TiO2 nanoparticles.

    PubMed

    Yan, Yuting; Liu, Qian; Du, Xiaojiao; Qian, Jing; Mao, Hanping; Wang, Kun

    2015-01-01

    We have demonstrated a facile approach for fabricating graphene quantum dots-TiO2 (GQDs-TiO2) nanocomposites by a simple physical adsorption method. Compared with pure GQDs and TiO2 nanoparticles (NPs), the as-prepared GQDs-TiO2 nanocomposites showed enhanced photoelectrochemical (PEC) signal under visible-light irradiation. The photocurrent of GQDs-TiO2/GCE was nearly 30-fold and 12-fold enhancement than that of GQDs/GCE and TiO2/GCE, respectively, which was attributed to the synergistic amplification between TiO2 NPs and GQDs. More interestingly, the photocurrent of GQDs-TiO2 nanocomposites was selectively sensitized by dopamine (DA), and enhanced with the increasing of DA concentration. Further, a new PEC methodology for ultrasensitive determination of DA was developed, which showed linearly enhanced photocurrent by increasing the DA concentration from 0.02 to 105 μM with a detection limit of 6.7 nM (S/N=3) under optimized conditions. This strategy opens up a new avenue for the application of GQDs-based nanocomposites in the field of PEC sensing and monitoring.

  9. Ag nanoclusters could efficiently quench the photoresponse of CdS quantum dots for novel energy transfer-based photoelectrochemical bioanalysis.

    PubMed

    Zhang, Ling; Sun, Yue; Liang, Yan-Yu; He, Jian-Ping; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-11-15

    Herein the influence of ultrasmall Ag nanoclusters (Ag NCs) against CdS quantum dots (QDs) in a photoelectrochemical (PEC) nanosystem was exploited for the first time, based on which a novel PEC bioanalysis was successfully developed via the efficient quenching effect of Ag NCs against the CdS QDs. In a model system, DNA assay was achieved by using molecular beacon (MB) probes anchored on a CdS QDs modified electrode, and the MB probes contain two segments that can hybridize with both target DNA sequence and the label of DNA encapsulated Ag NCs. After the MB probe was unfolded by the target DNA sequence, the labels of oligonucleotide encapsulated Ag NCs would be brought in close proximity to the CdS QDs electrode surface, and efficient photocurrent quenching of QDs could be resulted from an energy transfer process that originated from NCs. Thus, by monitoring the attenuation in the photocurrent signal, an elegant and sensitive PEC DNA bioanalysis could be accomplished. The developed biosensor displayed a linear range from 1.0pM to 10nM and the detection limit was experimentally found to be of 0.3pM. This work presents a feasible signaling principle that could act as a common basis for general PEC bioanalysis development.

  10. Photoelectrochemical bioanalysis: the state of the art.

    PubMed

    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2015-02-01

    The evolution of photoelectrochemical (PEC) bioanalysis has resulted in substantial progress in its analytical performance and biodetection applications. The aim of this review is to provide a panoramic snapshot of the state of the art in this dynamically developing field, with special emphasis on PEC DNA analysis, immunoassay, enzymatic biosensing and cell-related detection. The future prospects in this area are also evaluated and discussed. This work will serve as a useful source to inform the interested audience of the latest developments and applications in the field of PEC bioanalysis. PMID:25223761

  11. A generalized in situ electrodeposition of Zn doped CdS-based photoelectrochemical strategy for the detection of two metal ions on the same sensing platform.

    PubMed

    Zhang, Yong; Ma, Hongmin; Wu, Dan; Li, Rongxia; Wang, Xueping; Wang, Yaoguang; Zhu, Wenjuan; Wei, Qin; Du, Bin

    2016-03-15

    An efficient strategy for the sensitive detection of Cd(2+) and Cu(2+) on the same sensing platform was first developed based on the photocurrents generated from the electrodeposited Zn doped CdS (CdZnS) film. The enhancement of the photocurrents, which was directly obtained from the in situ electrodeposited CdZnS on ITO with the gradual addition of Cd(2+), was used an indicator for the content of Cd(2+) with theoretical and technical simplicity. Moreover, the electrodeposited CdZnS was further applied to sensing of Cu(2+) based on the interaction between Cu(2+) and S(2-) by immersing the hetero-structural film electrode into a Cu(2+)-containing sample for an appropriate time, leading to decrease the photocurrent of CdZnS. The decrease extent of photocurrent was depended on the concentration of Cu(2+) in the sample solution. Due to the sensitivity of the photoelectrochemical (PEC) sensor was enhanced obviously through the doping of Zn, the present electrodeposited PEC method demonstrated acceptable linear range of 10(-9)-10(-2)M and 10(-8)-10(-4)M, with low detection limit down to 0.35 nM and 3 nM for Cd(2+) and Cu(2+) respectively, which were lower than the Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines. The proposed CdZnS-based PEC strategy achieved two metal ions detection on the same sensing platform, which had positive and significant effect on solving the common problems, such as time-consuming, high cost, complex operation and high detection limit in the detection of metal ions. In addition, the proposed PEC device was further successfully applied to an assay of Cd(2+) and Cu(2+) in water sample. PMID:26528808

  12. A generalized in situ electrodeposition of Zn doped CdS-based photoelectrochemical strategy for the detection of two metal ions on the same sensing platform.

    PubMed

    Zhang, Yong; Ma, Hongmin; Wu, Dan; Li, Rongxia; Wang, Xueping; Wang, Yaoguang; Zhu, Wenjuan; Wei, Qin; Du, Bin

    2016-03-15

    An efficient strategy for the sensitive detection of Cd(2+) and Cu(2+) on the same sensing platform was first developed based on the photocurrents generated from the electrodeposited Zn doped CdS (CdZnS) film. The enhancement of the photocurrents, which was directly obtained from the in situ electrodeposited CdZnS on ITO with the gradual addition of Cd(2+), was used an indicator for the content of Cd(2+) with theoretical and technical simplicity. Moreover, the electrodeposited CdZnS was further applied to sensing of Cu(2+) based on the interaction between Cu(2+) and S(2-) by immersing the hetero-structural film electrode into a Cu(2+)-containing sample for an appropriate time, leading to decrease the photocurrent of CdZnS. The decrease extent of photocurrent was depended on the concentration of Cu(2+) in the sample solution. Due to the sensitivity of the photoelectrochemical (PEC) sensor was enhanced obviously through the doping of Zn, the present electrodeposited PEC method demonstrated acceptable linear range of 10(-9)-10(-2)M and 10(-8)-10(-4)M, with low detection limit down to 0.35 nM and 3 nM for Cd(2+) and Cu(2+) respectively, which were lower than the Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines. The proposed CdZnS-based PEC strategy achieved two metal ions detection on the same sensing platform, which had positive and significant effect on solving the common problems, such as time-consuming, high cost, complex operation and high detection limit in the detection of metal ions. In addition, the proposed PEC device was further successfully applied to an assay of Cd(2+) and Cu(2+) in water sample.

  13. Photoelectrochemical molecular comb

    DOEpatents

    Thundat, Thomas G.; Ferrell, Thomas L; Brown, Gilbert M.

    2012-02-07

    A method, system, and apparatus are provided for separating molecules, such as biomolecules. The method, system, and apparatus utilize an electrochemical cell having at least two electrodes, one electrode comprising a photo-sensitive material capable of generating a photopotential. Molecules are moved through an electrolyte medium between the at least two electrodes based upon localized photopotentials.

  14. Photoelectrochemical molecular comb

    DOEpatents

    Thundat, Thomas G.; Ferrell, Thomas L.; Brown; Gilbert M.

    2007-05-01

    A method, system, and apparatus are provided for separating molecules, such as biomolecules. The method, system, and apparatus utilize an electrochemical cell having at least to electrodes, one electrode comprising a photo-sensitive material capable of generating a photopotential. Molecules are moved through an electrolyte medium between the at least two electrodes based upon localized photopotentials.

  15. Thermo photo-electrochemical effect in n-InP/aqueous solution of orange dye/C cell

    NASA Astrophysics Data System (ADS)

    Ali, Taimoor; Karimov, Khasan S.; Akhmedov, Khakim M.; Kabutov, K.; Farooq, Amjad

    2015-03-01

    The effect of light and heat is studied on the electrical properties of an electrochemical n-InP/aqueous solution of orange dye/C cell. The cell is investigated under the light and heat of filament bulb. The n-type indium phosphide and carbon plates are used as electrodes. The aqueous solution of organic material orange dye (C17H17N5O2) in distilled water is served as electrolyte at 1, 3 and 5 wt. % concentration. The cell is assembled in sealed organic glass box with dimensions 35 × 13 × 14 mm. The open circuit voltage ( V oc ) and short circuit current ( I sc ) of the cell are observed by illuminating and heating the samples. The temperature is raised up to 60°C from 25°C when light intensity is increased from dark condition to 425 W/m2. It is observed that the relationship between light intensity and temperature is approximately linear for all cases. The V oc and I sc increase 100% and 300% respectively by increasing the light. The reported n-InP/aqueous solution of orange dye/C cell can be considered as small converter of light and heat into electric power. [Figure not available: see fulltext.

  16. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity and methods for manufacturing such blends

    DOEpatents

    Skotheim, Terje

    1984-01-01

    There is disclosed a polymer blend of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  17. Polymer blends for use in photoelectrochemical cells for conversion of solar energy to electricity and methods for manufacturing such blends

    DOEpatents

    Skotheim, T.

    A polymer blend is disclosed of a highly conductive polymer and a solid polymer electrolyte that is designed to achieve better charge transfer across the conductive film/polymer electrolyte interface of the electrochemical photovoltaic cell. The highly conductive polymer is preferably polypyrrole or poly-N-p-nitrophenylpyrrole and the solid polymer electrolyte is preferably polyethylene oxide or polypropylene oxide.

  18. Photoelectrochemical activity of titanium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Mehdinezhad Roshan, Aida

    Crystalline titanium dioxide (TiO2) thin films have been extensively investigated due to their various applications in a wide range of field such as photocatalysis, solar cells, gas sensors, self-cleaning windows, etc. The general objective of the present work can be categorized into two different parts. The first part of research is to acquire a fundamental understanding of thin film deposition and characterization of materials surfaces produced by Electrolytic Plasma Processing (EPP) and Magnetron Sputtering system. It has been tried to develop a crystalline layer of titanium dioxide thin film using these two techniques. Aluminum and titanium are the substrate materials. Also a part of study is to clean and roughen the substrate prior to the deposition to examine the effect of morphology. Aluminum was chosen as the substrate as well as titanium in order to enable us to get cheaper product. Second main portion of this work is to check the photoelectrochemical response of the deposited film and explore the effect of various parameters of coating process on this photoelectrochemical response.

  19. Photoelectrochemical fabrication of spectroscopic diffraction gratings

    NASA Technical Reports Server (NTRS)

    Rauh, R. David; Carrabba, Michael M.; Nguyen, Nguyet M.

    1986-01-01

    Photoelectrochemical etching was demonstrated as a means of fabricating a variety of periodic structures in semiconductors. The semiconductor is used as an electrode in an electrochemical cell, and is in contact with a liquid electrolyte. When the crystal is held at a positive voltage and illuminated, etching occurs in only the illuminated regions to a depth proportional to the illumination intensity and exposure time. In Phase 1, it was determined that diffraction gratings could be produced in gallium arsenide crystals by this method, using either a scanned focused laser beam or by uniform illumination of a ruling mask defined in metal or photoresist on the crystal surface. The latter approach was determined to produce V-grooves if the mask is oriented along certain crystallographic directions. These V-grooves were produced with an exceedingly smooth crystal morphology due to the highly controllable nature of the process and the mild electrolytes involved. The results form the basis for photoelectrochemical fabrication of deep, low pitch Eschelle gratings for use in high orders in NASA spectrographic instrumentation such as the Space Telescope Imaging Spectrograph.

  20. Optical and photoelectrochemical performance study based on n-ZnO nanorod arrays/p-CuAlO2 laminar films/Ni heterojunction

    NASA Astrophysics Data System (ADS)

    Ding, Juan; Yang, Haibin; Deng, Weiwen

    2014-06-01

    A novel ZnO nanorod arrays (NRs)/CuAlO2 laminar films heterojunction nanostructure was grown on the substrate of Ni plates using sol-gel synthesis for laminar films and subsequent hydrothermal reaction for nanorod arrays. The surface morphology, structure, optical and photoelectrochemical behaviors of this heterojunction were considered. Two significant absorption peaks of UV-vis spectra and a favorable forward current to reverse current ratio at applied voltage of -0.7 V to +2 V were observed in this heterojunction. Furthermore, the photoelectrochemical property was indicated that the highest photocurrent of 0.67 mA/cm2 was obtained under AM 1.5 illumination (vs Ag/AgCl). This heterojunction will play an important role in the optoelectronic fields and can be extended to other binary or ternary oxide compositions for optoelectronic applications.

  1. FeS2 quantum dots sensitized nanostructured TiO2 solar cell: photoelectrochemical and photoinduced absorption spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Bedja, I.

    2011-09-01

    Thin films of nanostructured TiO2 have been modified with FeS2 (pyrite) nano-particles by a low temperature chemical reaction of iron pentacarbonyl with sulfur in xylene. Quantum size effects are manifested by the observation of a blue shift in both absorption and photocurrent action spectra. PIA (Photoinduced absorption spectroscopy), where the excitation is provided by a square-wave modulated (on/off) monochromatic light emitting diode, is a multipurpose tool in the study of dye-sensitized solar cells. Here, PIA is used to study quantum-dot modified TiO2 nanostructured electrodes. The PIA spectra obtained give evidence for long-lived photoinduced charge separation: electrons are injected into the metal oxide and holes are left behind in the FeS2 quantum dot. Time-resolved PIA shows that recombination between electrons and holes occurs on a millisecond timescale. The Incident-Photon-to-Current Efficiency of about 23 % was obtained at 400 nm excitation. The performances of TiO2 electrodes modified with FeS2 are relatively low, which is explained by the presence of FeS2 phases other than the photoactive pyrite phase, as follows from the XRD spectrum.

  2. Recent advances in semiconductors for photocatalytic and photoelectrochemical water splitting.

    PubMed

    Hisatomi, Takashi; Kubota, Jun; Domen, Kazunari

    2014-11-21

    Photocatalytic and photoelectrochemical water splitting under irradiation by sunlight has received much attention for production of renewable hydrogen from water on a large scale. Many challenges still remain in improving energy conversion efficiency, such as utilizing longer-wavelength photons for hydrogen production, enhancing the reaction efficiency at any given wavelength, and increasing the lifetime of the semiconductor materials. This introductory review covers the fundamental aspects of photocatalytic and photoelectrochemical water splitting. Controlling the semiconducting properties of photocatalysts and photoelectrode materials is the primary concern in developing materials for solar water splitting, because they determine how much photoexcitation occurs in a semiconductor under solar illumination and how many photoexcited carriers reach the surface where water splitting takes place. Given a specific semiconductor material, surface modifications are important not only to activate the semiconductor for water splitting but also to facilitate charge separation and to upgrade the stability of the material under photoexcitation. In addition, reducing resistance loss and forming p-n junction have a significant impact on the efficiency of photoelectrochemical water splitting. Correct evaluation of the photocatalytic and photoelectrochemical activity for water splitting is becoming more important in enabling an accurate comparison of a number of studies based on different systems. In the latter part, recent advances in the water splitting reaction under visible light will be presented with a focus on non-oxide semiconductor materials to give an overview of the various problems and solutions.

  3. Microfluidic paper-based analytical device for photoelectrochemical immunoassay with multiplex signal amplification using multibranched hybridization chain reaction and PdAu enzyme mimetics.

    PubMed

    Lan, Feifei; Sun, Guoqiang; Liang, Linlin; Ge, Shenguang; Yan, Mei; Yu, Jinghua

    2016-05-15

    Combining multibranched hybridization chain reaction (mHCR), the photoelectrochemical (PEC) immunosensor was fabricated with a microfluidic paper-based analytical devices using different sizes of CdTe quantum dots (QDs) sensitized flower-like 3D ZnO superstructures as photoactive materials. Firstly, 4-aminothiophenol (PATP) functioned ZnO was anchored on gold-paper working electrode. With the aid of PATP, large-sized CdTe-COOH QDs (QDs1) were conjugated onto the ZnO surface because of the formation of a strong bond (Zn-S) between the thiol of PATP molecule and the ZnO, and the remaining amino group formed an amide bond with carboxylic acid group capping CdTe. Then the small-sized CdTe-NH2 QDs (QDs2) were modified on the QDs1 by forming amide bond, which leaded to a very strong photocurrent response because of the formation of cosensitized structure. The designed mHCR produced long products with multiple branched arms, which could attached multiple PdAu nanoparticles and catalyze the oxidation of hydroquinone (HQ) using H2O2 as anoxidant. Double strands DNA with multiple branched arms (mdsDNA) was formed by mHCR. In the presence of carcinoembryonic antigen (CEA), PdAu-mdsDNA conjugates-labeled CEA antibody was captured. The concentrations of CEA were measured through the decrease in photocurrent intensity resulting from the increase in steric hindrance of the immunocomplex and the polymeric oxidation product of HQ. In addition, the oxidation product of HQ deposited on the as-obtained electrode, which could efficiently inhibit the photoinduced electron transfer. Under optimal conditions, the PEC immunosensor exhibited excellent analytical performance: the detection range of CEA was from 0.001 to 90 ng mL(-1) with low detection limit of 0.33 pg mL(-1). The as-obtained immunosensor exhibited excellent precision, prominent specificity, acceptable stability and reproducibility, and could be used for the detection of CEA in real samples. The proposed assay opens a

  4. Effective signal-on photoelectrochemical immunoassay of subgroup J avian leukosis virus based on Bi2S3 nanorods as photosensitizer and in situ generated ascorbic acid for electron donating.

    PubMed

    Sun, Bing; Qiao, Fengmin; Chen, Lijian; Zhao, Zhen; Yin, Huanshun; Ai, Shiyun

    2014-04-15

    A universal and effective photoelectrochemical (PEC) immunosensing device was fabricated on an indium tin oxide (ITO) electrode for sensitive and specific detection of subgroup J of avian leukosis virus (ALVs-J) based on a signal-on strategy. Bismuth sulfide (Bi2S3) nanorods, with good morphology, high crystallinity and differentiated PEC properties, were selected as the photoelectrochemical species and synthesized by a facile hydrothermal method. On the basis of alkaline phosphatase catalytic chemistry to in situ produce ascorbic acid for electron donating, an enhanced photocurrent was obtained. Due to the dependence of the photocurrent signal on the concentration of generated electron donor, an exquisite immunosandwich protocol was successfully constructed for PEC detection of ALVs-J with a linear range from 10(2.14) to 10(3.65) TCID50/mL. The detection limit was 10(2.08) TCID50/mL (S/N=3), and high stability and specificity were obtained. The strategy provides a fast and sensitive method for ALVs-J analysis and opens a general format for future development of PEC immunoanalysis.

  5. Charge-transfer-to-solvent photochemistry of electrode-confined ferrocene- and cobaltocene-based polymers. Photoelectrochemical reduction of halocarbons

    SciTech Connect

    Tatistcheff, H.B.; Hancock, L.F.; Wrighton, M.S.

    1995-05-11

    Like the metallocenes themselves, metallocene-based polymers exhibit near-UV charge-transfer-to-solvent (CTTS) absorption in the presence of CCl{sub 4}, CHCl{sub 3}, CH{sub 2}Cl{sub 2}, CBr{sub 4}, and CHBr{sub 3}. The photoelectrochemistry of charge transfer complexes of two ferrocene-containing polymers and one cobaltocene-containing polymer has been studied. When the metallocene-based polymer is confined to the surface of an electrode that is held at a potential negative of the formal potential of the metallocene, near-UV excitation results in sustained cathodic current in electrolyte solutions containing halocarbons. The wavelength, acceptor, and potential dependences are in accord with a sustained current that is due to a metallocene-to-halocarbon CTTS absorption where the photoprocess results in the reduction of the halocarbon at an electrode potential significantly positive of where electrochemical reduction occurs in the dark. The octamethylferrocene-based system shows a more negative potential onset and a longer wavelength offset of photocurrent than the simple ferrocene-based system, consistent with the electron-releasing nature of the methyl substituents. The onset of photocurrent in the cobaltocene-based system occurs at the most negative potential of the three, consistent with the cobaltocene-based system having the most negative formal potential of the metallocenes studied. 13 refs., 5 figs., 1 tab.

  6. Photo-electrochemical and physical characterizations of a new single crystal POM-based material. Application in photocatalysis

    NASA Astrophysics Data System (ADS)

    Meziani, D.; Abdmeziem, K.; Bouacida, S.; Trari, M.

    2016-12-01

    A new inorganic-organic hybrid material [(H2pip)3][α-PW12O40]2·4H2O, prepared by hydrothermal method, was structurally characterized by single-crystal X-ray diffraction. The compound based on a Keggin-type polyoxotungstate and piperazine (pip) displays a hybrid framework built from two (α-Keggin)3- polyoxoanions and three (H2pip)2+ hydrogen-bonded fragments, forming 3-D supramolecular architecture. The diffuse reflectance spectrum shows two optical transitions directly (3.27 eV) and indirectly (3.12 eV) allowed. The electrical conductivity follows an exponential law, indicating a semiconducting comportment with activation energy of 14 meV. The Mott-Schottky characteristic, plotted in Na2SO4 (0.5 M) solution indicates n-type conduction with a flat band potential of -0.084 VSCE and electrons density of 4.24 × 1018 cm-3. As application, the photo-degradation of methylene blue (MB) upon UV irradiation was successfully achieved by OH• radicals. The improved activity is attributed to the potentials closeness of the valence and conduction bands with the radical levels.

  7. Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling

    NASA Astrophysics Data System (ADS)

    Shi, Xinjian; Jeong, Hokyeong; Oh, Seung Jae; Ma, Ming; Zhang, Kan; Kwon, Jeong; Choi, In Taek; Choi, Il Yong; Kim, Hwan Kyu; Kim, Jong Kyu; Park, Jong Hyeok

    2016-06-01

    Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation.

  8. Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling.

    PubMed

    Shi, Xinjian; Jeong, Hokyeong; Oh, Seung Jae; Ma, Ming; Zhang, Kan; Kwon, Jeong; Choi, In Taek; Choi, Il Yong; Kim, Hwan Kyu; Kim, Jong Kyu; Park, Jong Hyeok

    2016-06-21

    Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation.

  9. Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling.

    PubMed

    Shi, Xinjian; Jeong, Hokyeong; Oh, Seung Jae; Ma, Ming; Zhang, Kan; Kwon, Jeong; Choi, In Taek; Choi, Il Yong; Kim, Hwan Kyu; Kim, Jong Kyu; Park, Jong Hyeok

    2016-01-01

    Various tandem cell configurations have been reported for highly efficient and spontaneous hydrogen production from photoelectrochemical solar water splitting. However, there is a contradiction between two main requirements of a front photoelectrode in a tandem cell configuration, namely, high transparency and high photocurrent density. Here we demonstrate a simple yet highly effective method to overcome this contradiction by incorporating a hybrid conductive distributed Bragg reflector on the back side of the transparent conducting substrate for the front photoelectrochemical electrode, which functions as both an optical filter and a conductive counter-electrode of the rear dye-sensitized solar cell. The hybrid conductive distributed Bragg reflectors were designed to be transparent to the long-wavelength part of the incident solar spectrum (λ>500 nm) for the rear solar cell, while reflecting the short-wavelength photons (λ<500 nm) which can then be absorbed by the front photoelectrochemical electrode for enhanced photocurrent generation. PMID:27324578

  10. The role of ultra-thin SiO2 layers in metal-insulator-semiconductor (MIS) photoelectrochemical devices (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Esposito, Daniel V.

    2015-08-01

    Solid-state junctions based on a metal-insulator-semiconductor (MIS) architecture are of great interest for a number of optoelectronic applications such as photovoltaics, photoelectrochemical cells, and photodetection. One major advantage of the MIS junction compared to the closely related metal-semiconductor junction, or Schottky junction, is that the thin insulating layer (1-3 nm thick) that separates the metal and semiconductor can significantly reduce the density of undesirable interfacial mid-gap states. The reduction in mid-gap states helps "un-pin" the junction, allowing for significantly higher built-in-voltages to be achieved. A second major advantage of the MIS junction is that the thin insulating layer can also protect the underlying semiconductor from corrosion in an electrochemical environment, making the MIS architecture well-suited for application in (photo)electrochemical applications. In this presentation, discontinuous Si-based MIS junctions immersed in electrolyte are explored for use as i.) photoelectrodes for solar-water splitting in photoelectrochemical cells (PECs) and ii.) position-sensitive photodetectors. The development and optimization of MIS photoelectrodes for both of these applications relies heavily on understanding how processing of the thin SiO2 layer impacts the properties of nano- and micro-scale MIS junctions, as well as the interactions of the insulating layer with the electrolyte. In this work, we systematically explore the effects of insulator thickness, synthesis method, and chemical treatment on the photoelectrochemical and electrochemical properties of these MIS devices. It is shown that electrolyte-induced inversion plays a critical role in determining the charge carrier dynamics within the MIS photoelectrodes for both applications.

  11. A new signal amplification strategy of photoelectrochemical immunoassay for highly sensitive interleukin-6 detection based on TiO2/CdS/CdSe dual co-sensitized structure.

    PubMed

    Fan, Gao-Chao; Ren, Xiao-Lin; Zhu, Cheng; Zhang, Jian-Rong; Zhu, Jun-Jie

    2014-09-15

    Dual co-sensitized structure of TiO2/CdS/CdSe was designed to develop a novel photoelectrochemical immunoassay for highly sensitive detection of human interleukin-6 (IL-6). To construct a sensing electrode, TiO2/CdS hybrid was prepared by successive adsorption and reaction of Cd(2+) and S(2-) ions on the surface of TiO2 and then was employed as matrix for immobilization of anti-IL-6 antibody, whereas CdSe QDs linked to IL-6 were used for signal amplification via the specific antibody-antigen immunoreaction between anti-IL-6 and IL-6-CdSe bioconjugate. Greatly enhanced sensitivity for IL-6 detection was derived from the new co-sensitization signal amplification strategy. First, the TiO2/CdS/CdSe co-sensitized structure extended the absorption range to long wavelength of white light, which adequately utilized the light energy. Second, the TiO2/CdS/CdSe co-sensitized structure possessed stepwise band-edge levels favoring ultrafast transfer of photogenerated electrons and significantly prompted the photoelectrochemical performance. Besides, the introduction of CdSe effectively prevented the recombination of photogenerated electrons in the conduction band of CdS, further causing an enhanced photocurrent. Accordingly, upon the co-sensitization strategy, a novel immunoassay based on the competitive binding of anti-IL-6 antibody with IL-6 antigen and IL-6-CdSe bioconjugate was developed, and it exhibited a wide linear range from 1.0 pg/mL to 100 ng/mL with a low detection limit of 0.38 pg/mL for IL-6 detection. The proposed co-sensitization strategy presented high sensitivity, reproducibility, specificity and stability, and also opened up a new promising platform for detection of other biomarkers.

  12. Photoelectrochemical Immunosensor for Detection of Carcinoembryonic Antigen Based on 2D TiO2 Nanosheets and Carboxylated Graphitic Carbon Nitride.

    PubMed

    Wang, Huan; Wang, Yaoguang; Zhang, Yong; Wang, Qi; Ren, Xiang; Wu, Dan; Wei, Qin

    2016-06-06

    Carcinoembryonic antigen (CEA) was used as the model, an ultrasensitive label-free photoelectrochemical immunosensor was developed using 2D TiO2 nanosheets and carboxylated graphitic carbon nitride (g-C3N4) as photoactive materials and ascorbic acid as an efficient electron donor. 2D TiO2 nanosheets was sythsized by surfactant self-assembly method and proved to have higher photoelectrochemical signals than TiO2 nanoparticles. Firstly, carboxylated g-C3N4 could be attached to 2D TiO2 nanosheets through the bond formed between carboxyl group of carboxylated g-C3N4 and TiO2. And the photocurrent of g-C3N4/TiO2 drastically enhances compared to carboxylated g-C3N4 and TiO2. Then, antibody of CEA was bonded to TiO2 through the dentate bond formed between carboxyl group of anti-CEA and TiO2, leading to the decrease of the photocurrents. As proven by PEC experiments and electrochemical impedance spectroscopy (EIS) analysis, the fabrication process of the immunosensor is successful. Under the optimal conditions, the intensity decreased linearly with CEA concentration in the range of 0.01~10 ng/mL. The detection limit is 2.1 pg/mL. The work provides an effective method for the detection of tumor markers and can be extended for the application in food safety and environmental monitoring analysis.

  13. Photoelectrochemical Immunosensor for Detection of Carcinoembryonic Antigen Based on 2D TiO2 Nanosheets and Carboxylated Graphitic Carbon Nitride

    PubMed Central

    Wang, Huan; Wang, Yaoguang; Zhang, Yong; Wang, Qi; Ren, Xiang; Wu, Dan; Wei, Qin

    2016-01-01

    Carcinoembryonic antigen (CEA) was used as the model, an ultrasensitive label-free photoelectrochemical immunosensor was developed using 2D TiO2 nanosheets and carboxylated graphitic carbon nitride (g-C3N4) as photoactive materials and ascorbic acid as an efficient electron donor. 2D TiO2 nanosheets was sythsized by surfactant self-assembly method and proved to have higher photoelectrochemical signals than TiO2 nanoparticles. Firstly, carboxylated g-C3N4 could be attached to 2D TiO2 nanosheets through the bond formed between carboxyl group of carboxylated g-C3N4 and TiO2. And the photocurrent of g-C3N4/TiO2 drastically enhances compared to carboxylated g-C3N4 and TiO2. Then, antibody of CEA was bonded to TiO2 through the dentate bond formed between carboxyl group of anti-CEA and TiO2, leading to the decrease of the photocurrents. As proven by PEC experiments and electrochemical impedance spectroscopy (EIS) analysis, the fabrication process of the immunosensor is successful. Under the optimal conditions, the intensity decreased linearly with CEA concentration in the range of 0.01~10 ng/mL. The detection limit is 2.1 pg/mL. The work provides an effective method for the detection of tumor markers and can be extended for the application in food safety and environmental monitoring analysis. PMID:27263659

  14. Dynamic and reversible self-assembly of photoelectrochemical complexes based on lipid bilayer disks, photosynthetic reaction centers, and single-walled carbon nanotubes.

    PubMed

    Boghossian, Ardemis A; Choi, Jong Hyun; Ham, Moon-Ho; Strano, Michael S

    2011-03-01

    An aqueous solution containing photosynthetic reaction centers (RCs), membrane scaffold proteins (MSPs), phospholipids, and single-walled carbon nanotubes (SWCNTs) solubilized with the surfactant sodium cholate (SC) reversibly self-assembles into a highly ordered structure upon dialysis of the latter. The resulting structure is photoelectrochemically active and consists of 4-nm-thick lipid bilayer disks (nanodisks, NDs) arranged parallel to the surface of the SWCNT with the RC housed within the bilayer such that its hole injecting site faces the nanotube surface. The structure can be assembled and disassembled autonomously with the addition or removal of surfactant. We model the kinetic and thermodynamic forces that drive the dynamics of this reversible self-assembly process. The assembly is monitored using spectrofluorimetry during dialysis and subsequent surfactant addition and used to fit a kinetic model to determine the forward and reverse rate constants of ND and ND-SWCNT formation. The calculated ND and ND-SWCNT forward rate constants are 79 mM(-1) s(-1) and 5.4 × 10(2) mM(-1) s(-1), respectively, and the reverse rate constants are negligible over the dialysis time scale. We find that the reaction is not diffusion-controlled since the ND-SWCNT reaction, which consists of entities with smaller diffusion coefficients, has a larger reaction rate constant. Using these rate parameters, we were able to develop a kinetic phase diagram for the formation of ND-SWCNT complexes, which indicates an optimal dialysis rate of approximately 8 × 10(-4) s(-1). We also fit the model to cyclic ND-SWCNT assembly and disassembly experiments and hence mimic the thermodynamic forces used in regeneration processes detailed previously. Such forces may form the basis of both synthetic and natural photoelectrochemical complexes capable of dynamic component replacement and repair.

  15. Novel catalysts and photoelectrochemical system for solar fuel production

    NASA Astrophysics Data System (ADS)

    Zhang, Yan

    Solar fuel production from abundant raw chemicals such as CO2 and water is highly desired as a clean renewable energy solution for the future. Developing photoelectrochemical cells is viewed as a promising approach to realize this energy conversion and storage process. Efficient and robust oxygen evolution catalyst made from non-precious materials remains a major challenge for such a system. This thesis basically consists of three parts of work, including studies on enhancing the photocatalytic oxygen evolution activity of cobalt-based spinel nanoparticles by manganese3+ substitution, in situ formation of cobalt oxide nanocubanes as highly active catalyst for photocatalytic oxygen evolution reaction, and development of a photoanode-driven photoelectrochemical cell for CO2 reduction with water. The first part of this thesis work devotes efforts in the development and study on cobalt and other transition metal oxide based oxygen evolution catalyst. Photocatalytic oxygen evolution is a critical step for solar fuel production from abundant sources. It poses a significant challenge because it requires an efficient catalyst to bridge the one-electron photon capture process with the four-electron oxygen reaction. Among all the metal oxides, Co3O4 spinel exhibits a high activity as an oxygen evolution catalyst. The results of this work demonstrate that the photocatalytic oxygen evolution activity of Co3O4 spinel can be further enhanced by substituting Co with Mn in the spinel structure. Using a facile hydrothermal approach, Co3O4 spinel nanoparticles as well as Mn-substituted and Ni-substituted Co3O4 spinel nanoparticles with a typical particle size of 5-7 nm were successfully synthesized. The morphology and crystal structures of the as-synthesized nanoparticle catalysts have been carefully examined using various structural characterization techniques, including powder x-ray diffraction (PXRD), transmission electron microscope (TEM), gas adsorption, and x-ray absorption

  16. Integrated photoelectrochemical energy storage: solar hydrogen generation and supercapacitor

    PubMed Central

    Xia, Xinhui; Luo, Jingshan; Zeng, Zhiyuan; Guan, Cao; Zhang, Yongqi; Tu, Jiangping; Zhang, Hua; Fan, Hong Jin

    2012-01-01

    Current solar energy harvest and storage are so far realized by independent technologies (such as solar cell and batteries), by which only a fraction of solar energy is utilized. It is highly desirable to improve the utilization efficiency of solar energy. Here, we construct an integrated photoelectrochemical device with simultaneous supercapacitor and hydrogen evolution functions based on TiO2/transition metal hydroxides/oxides core/shell nanorod arrays. The feasibility of solar-driven pseudocapacitance is clearly demonstrated, and the charge/discharge is indicated by reversible color changes (photochromism). In such an integrated device, the photogenerated electrons are utilized for H2 generation and holes for pseudocapacitive charging, so that both the reductive and oxidative energies are captured and converted. Specific capacitances of 482 F g−1 at 0.5 A g−1 and 287 F g−1 at 1 A g−1 are obtained with TiO2/Ni(OH)2 nanorod arrays. This study provides a new research strategy for integrated pseudocapacitor and solar energy application. PMID:23248745

  17. Integrated photoelectrochemical energy storage: solar hydrogen generation and supercapacitor.

    PubMed

    Xia, Xinhui; Luo, Jingshan; Zeng, Zhiyuan; Guan, Cao; Zhang, Yongqi; Tu, Jiangping; Zhang, Hua; Fan, Hong Jin

    2012-01-01

    Current solar energy harvest and storage are so far realized by independent technologies (such as solar cell and batteries), by which only a fraction of solar energy is utilized. It is highly desirable to improve the utilization efficiency of solar energy. Here, we construct an integrated photoelectrochemical device with simultaneous supercapacitor and hydrogen evolution functions based on TiO(2)/transition metal hydroxides/oxides core/shell nanorod arrays. The feasibility of solar-driven pseudocapacitance is clearly demonstrated, and the charge/discharge is indicated by reversible color changes (photochromism). In such an integrated device, the photogenerated electrons are utilized for H(2) generation and holes for pseudocapacitive charging, so that both the reductive and oxidative energies are captured and converted. Specific capacitances of 482 F g(-1) at 0.5 A g(-1) and 287 F g(-1) at 1 A g(-1) are obtained with TiO(2)/Ni(OH)(2) nanorod arrays. This study provides a new research strategy for integrated pseudocapacitor and solar energy application.

  18. Integrated photoelectrochemical energy storage: solar hydrogen generation and supercapacitor

    NASA Astrophysics Data System (ADS)

    Xia, Xinhui; Luo, Jingshan; Zeng, Zhiyuan; Guan, Cao; Zhang, Yongqi; Tu, Jiangping; Zhang, Hua; Fan, Hong Jin

    2012-12-01

    Current solar energy harvest and storage are so far realized by independent technologies (such as solar cell and batteries), by which only a fraction of solar energy is utilized. It is highly desirable to improve the utilization efficiency of solar energy. Here, we construct an integrated photoelectrochemical device with simultaneous supercapacitor and hydrogen evolution functions based on TiO2/transition metal hydroxides/oxides core/shell nanorod arrays. The feasibility of solar-driven pseudocapacitance is clearly demonstrated, and the charge/discharge is indicated by reversible color changes (photochromism). In such an integrated device, the photogenerated electrons are utilized for H2 generation and holes for pseudocapacitive charging, so that both the reductive and oxidative energies are captured and converted. Specific capacitances of 482 F g-1 at 0.5 A g-1 and 287 F g-1 at 1 A g-1 are obtained with TiO2/Ni(OH)2 nanorod arrays. This study provides a new research strategy for integrated pseudocapacitor and solar energy application.

  19. Synthesis and characterization of Cd{sub 0.7}Pb{sub 0.3}Se thin films for photoelectrochemical solar cell

    SciTech Connect

    Delekar, S.D.; Patil, M.K.; Jadhav, B.V.; Sanadi, K.R.; Hankare, P.P.

    2010-03-15

    Optimum composition Cd{sub 0.7}Pb{sub 0.3}Se thin films have been deposited using the chemical bath containing cadmium sulfate octahydrate, lead nitrate, tartaric acid, potassium hydroxide, ammonia, and sodium selenosulfate onto fluorine-doped tin oxide glass substrate. The various deposition parameters such as composition of reactive bath, pH of the solution, deposition temperature, deposition time, speed of rotation, etc. have been optimized for obtaining good quality film. X-ray diffraction studies revealed the polycrystalline nature of sample with the solid solution of lead (II) ions in CdSe host lattice, having a hexagonal phase structure. Scanning electron micrograph suggested that the grains were non-uniformly distributed over the substrate surface. Film composition was determined by atomic absorption spectroscopy as well as energy dispersive X-ray atomic spectroscopy. Optical absorption data showed the presence of direct transition with energy band gap 1.80 eV for the deposited thin films. The dark specific conductance of Cd{sub 0.7}Pb{sub 0.3}Se thin films was found to the order of 10{sup -6} ({omega} cm){sup -1} having n-type semiconducting nature. Photoelectrochemical characterization was carried out using sulfide/polysulfide electrolyte with 1.401% efficiency. (author)

  20. Photoelectrochemical hydrogen production

    SciTech Connect

    Rocheleau, R.E.; Miller, E.; Misra, A.

    1996-10-01

    The large-scale production of hydrogen utilizing energy provided by a renewable source to split water is one of the most ambitious long-term goals of the U.S. Department of Energy`s Hydrogen Program. One promising option to meet this goal is direct photoelectrolysis in which light absorbed by semiconductor-based photoelectrodes produces electrical power internally to split water into hydrogen and oxygen. Under this program, direct solar-to-chemical conversion efficiencies as high as 7.8 % have been demonstrated using low-cost, amorphous-silicon-based photoelectrodes. Detailed loss analysis models indicate that solar-to-chemical conversion greater than 10% can be achieved with amorphous-silicon-based structures optimized for hydrogen production. In this report, the authors describe the continuing progress in the development of thin-film catalytic/protective coatings, results of outdoor testing, and efforts to develop high efficiency, stable prototype systems.

  1. Chemically Modified Metal Oxide Nanostructure for Photoelectrochemical Water Splitting

    NASA Astrophysics Data System (ADS)

    Wang, Gongming

    Hydrogen gas is chemical fuel with high energy density, and represents a clean, renewable and carbon-free burning fuel, which has the potential to solve the more and more urgent energy crisis in today's society. Inspired by natural photosynthesis, artificial photosynthesis to generate hydrogen energy has attracted a lot of attentions in the field of chemistry, physics and material. Photoelectrochemical water splitting based on semiconductors represents a green and low cost method to generate hydrogen fuel. However, the current overall efficiency of solar to hydrogen is quite low, due to some intrinsic limitations such as bandgap, diffusion distance, carrier lifetime and photostability of semiconductors. Although nanostructured semiconductors can improve their photoelectrochemical water splitting performance to some extent, by increasing electrolyte accessible area and shortening minority carrier diffusion distance, nanostructure engineering cannot change their intrinsic electronic properties. Recent development in chemically modified nanostructures such as surface catalyst decoration, element doping, plasmonic modification and interfacial hetero-junction design have led to significant advancement in the photoelectrochemical water splitting, by improving surface reaction kinetics and charge separation, transportation and collection efficiency. In this thesis, I will give a detailed discussion on the chemically modified metal oxide nanostructures for photoelectrocemical hydrogen generation, with a focus on the element doping, hydrogen treatment and catalyst modification. I have demonstrated nitrogen doping on ZnO and Ti doping on hematite can improve their photoelectrochemical performance. In addition, we found hydrogen treatment is a general and effective method to improve the photocatalytic performance, by increasing their carrier desities. Hydrogen treatment has been demonstrated on TiO2, WO3 and BiVO4. In the end, we also used electrochemical catalyt to modify

  2. Photoelectrochemical detection of metal ions.

    PubMed

    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-07-21

    Depending on the situation, metal ions may either play beneficial roles or be harmful to human health and ecosystems. Sensitive and accurate detection of metal ions is thus a critical issue in the field of analytical sciences and great efforts have been devoted to the development of various metal ion sensors. Photoelectrochemical (PEC) detection is an emerging technique for the bio/chemical detection of metal ions, and features a fast response, low cost and high sensitivity. Using representative examples, this review will first introduce the fundamentals and summarize recent progress in the PEC detection of metal ions. In addition, interesting strategies for the design of particular PEC metal ion sensors are discussed. Challenges and opportunities in this field are also presented. PMID:27297834

  3. Light addressable photoelectrochemical cyanide sensor

    SciTech Connect

    Licht, S.; Myung, N.; Sun, Y.

    1996-03-15

    A sensor is demonstrated that is capable of spatial discrimination of cyanide with use of only a single stationary sensing element. Different spatial regions of the sensing element are light activated to reveal the solution cyanide concentration only at the point of illumination. In this light addressable photoelectrochemical (LAP) sensor the sensing element consists of an n-CdSe electrode immersed in solution, with the open-circuit potential determined under illumination. In alkaline ferro-ferri-cyanide solution, the open-circuit photopotential is highly responsive to cyanide, with a linear response of (120 mV) log [KCN]. LAP detection with a spatial resolution of {+-}1 mm for cyanide detection is demonstrated. The response is almost linear for 0.001-0.100 m cyanide with a resolution of 5 mV. 38 refs., 7 figs., 1 tab.

  4. Photochemical solar cells based on dye-sensitization of nanocrystalline TiO2

    NASA Astrophysics Data System (ADS)

    Frank, A. J.; Gregg, B. A.; Grätzel, M.; Nozik, A. J.; Zaban, A.; Ferrere, S.; Schlichthörl, G.; Huang, S. Y.

    1997-04-01

    A new type of photovoltaic cell is described. It is a photoelectrochemical device that is based on the dye sensitization of thin (10-30 μm) films of TiO2 nanoparticles in contact with a non-aqueous liquid electrolyte. The cell is very simple to fabricate and, in principle, its color can be tuned through the visible spectrum, ranging from being completely transparent to black by changing the absorption characteristics of the dye; the photovoltage of the cell is not determined by the threshold energy for light absorption (bandgap) as in conventional photovoltaic cells based on solid-state semiconductors. The highest present efficiency of the dye-sensitized photochemical solar cell is about 11%. The cell has the potential to be a low-cost photovoltaic option. Unique applications include photovoltaic power windows and photoelectrochromic windows.

  5. Photoelectrochemical reduction of CO{sub 2} by silicate rock powders

    SciTech Connect

    Ohta, Kiyohisa; Ohguchi, Youko; Kaneco, Satoshi; Mizuno, Takayuki

    1999-06-01

    The reduction in CO{sub 2} emissions by photoelectrochemical conversion of the CO{sub 2} to formic acid and methanol using silicate rock (andesite) powders suspended in water is presented. For photoelectrochemical reduction of CO{sub 2}, a homemade cell with a platinum and a copper electrode was used. 0.1 M KHCO{sub 3} solution was used as the electrolyte. In the photoelectrochemical reduction of CO{sub 2} with a copper cathode in the catholyte dispersing andesite powder, mainly formic acid, methanol, methane, ethylene, carbon monoxide, and hydrogen were produced. Consequently, it was found that this method using a copper electrode was effective for formic acid and methanol formations from carbon dioxide.

  6. Enhanced photoelectrochemical aptasensing platform for TXNDC5 gene based on exciton energy transfer between NCQDs and TiO2 nanorods

    PubMed Central

    Pang, Xuehui; Wang, Lin; Ma, Hongmin; Zhang, Yong; Pan, Jihong; Chen, Yao; Du, Bin; Wei, Qin

    2016-01-01

    The over expression of thioredoxin domain-containing protein 5 (TXNDC5) can promote the growth of castration-resistant prostate cancer (CRPC). A novel highly sensitive photoelectrochemical (PEC) aptsensor was developed for the detection of TXNDC5 by using the nanohybrids (TiO2 NRs/NCQDs) of nitrogen-doped carbon quantum dots (NCQDs) and TiO2 nanorods as the photo-to-electron conversion medium. TiO2 NRs/NCQDs nanohybrids were prepared by controlling the experimental condition. TiO2 NRs were self-assembled to form the nanopores with good photocurrent conversion efficiency. NCQDs possessed carboxyl groups (−COOH) and amino groups (−NH2) in the preparation process. −COOH and −NH2 groups played important roles for anchoring the capture probes (5′ primer and 3′ primer) through covalent binding. The ultrasensitive and stable detection for TXNDC5 was achieved by the specific recognition between the capture probes and the targets. The fabricated aptsensor showed excellent performance with a wide linear range (0.5 fmol/L ∼ 10 nmol/L) and a low detection limit of 0.1 fmol/L. This kind of aptsensor would provide a potential application for TXNDC5. PMID:26777976

  7. In situ generation of electron acceptor for photoelectrochemical biosensing via hemin-mediated catalytic reaction.

    PubMed

    Zang, Yang; Lei, Jianping; Zhang, Lei; Ju, Huangxian

    2014-12-16

    A novel photoelectrochemical sensing strategy is designed for DNA detection on the basis of in situ generation of an electron acceptor via the catalytic reaction of hemin toward H2O2. The photoelectrochemical platform was established by sequential assembly of near-infrared CdTe quantum dots, capture DNA, and a hemin-labeled DNA probe to form a triple-helix molecular beacon (THMB) structure on an indium tin oxide electrode. According to the highly catalytic capacity of hemin toward H2O2, a photoelectrochemical mechanism was then proposed, in which the electron acceptor of O2 was in situ-generated on the electrode surface, leading to the enhancement of the photocurrent response. The utilization of CdTe QDs can extend the absorption edge to the near-infrared band, resulting in an increase in the light-to-electricity efficiency. After introducing target DNA, the THMB structure is disassembled and releases hemin and, thus, quenches the photocurrent. Under optimized conditions, this biosensor shows high sensitivity with a linear range from 1 to 1000 pM and detection limit of 0.8 pM. Moreover, it exhibits good performance of excellent selectivity, high stability, and acceptable fabrication reproducibility. This present strategy opens an alternative avenue for photoelectrochemical signal transduction and expands the applications of hemin-based materials in photoelectrochemical biosensing and clinical diagnosis.

  8. Semiconductor wire array structures, and solar cells and photodetectors based on such structures

    SciTech Connect

    Kelzenberg, Michael D.; Atwater, Harry A.; Briggs, Ryan M.; Boettcher, Shannon W.; Lewis, Nathan S.; Petykiewicz, Jan A.

    2014-08-19

    A structure comprising an array of semiconductor structures, an infill material between the semiconductor materials, and one or more light-trapping elements is described. Photoconverters and photoelectrochemical devices based on such structure also described.

  9. Increasing Efficiency in Photoelectrochemical Hydrogen Production

    SciTech Connect

    Warren, S.; Turner, J.

    2002-01-01

    Photoelectrochemical hydrogen production promises to be a renewable, clean, and efficient way of storing the sun's energy for use in hydrogen-powered fuel cells. We use p-type Ga.51In.49P semiconductor (henceforth as GaInP2) to absorb solar energy and produce a photocurrent. When the semiconductor is immersed in water, the photocurrent can break down water into hydrogen and oxygen. However, before the GaInP2 can produce hydrogen and oxygen, the conduction band and the Fermi level of the semiconductor must overlap the water redox potentials. In an unmodified system, the conduction band and Fermi level of GaInP2 do not overlap the water redox potentials. When light shines on the semiconductor, electrons build up on the surface, shifting the bandedges and Fermi level further away from overlap of the water redox potentials. We report on surface treatments with metallated porphyrins and transition metals that suppress bandedge migration and allow bandedge overlap to occur. Coating ruthenium octaethylporphyrin carbonyl (RuOEP CO) on the GaInP2 surface shifted bandedges in the positive direction by 270 mV on average, allowing the bandedges to frequently overlap the water redox potentials. Coating the GaInP2 surface with RuCl3 catalyzed charge transfer from the semiconductor to the water, lessening bandedge migration under light irradiation. Future work will focus on the long-term surface stability of these new treatments and quantitative applications of porphyrins.

  10. Photoelectrochemical conversion using reaction-centre electrodes

    NASA Astrophysics Data System (ADS)

    Janzen, A. F.; Seibert, M.

    1980-08-01

    The production of photovoltages and photocurrents by a bacterial photosynthetic reaction center coupled to an SnO2 electrode is reported. Reaction centers isolated from membranes of the purple, nonsulfur photosynthetic bacterium Rhodopseudomonas sphaeroides R-26 were transferred to working electrode surfaces and photoeffects were monitored in the external circuit of a photoelectrochemical cell consisting of the working electrode, a platinized platinum or SnO2 counter electrode and a 0.1 M Na2SO4 and 5 M hydroquinone in water or Tricine buffer electrolyte. Small open-circuit photovoltages and short-circuit photocurrents were observed for platinized platinum electrodes coated with a thin film of reaction centers both before and after autoclaving, indicating that biologically active electron transfer is not involved. Reaction-center electrodes made using SnO2-coated glass were observed to generate photovoltages up to 70 mV and photocurrents of 0.3 microamp/sq cm. In addition, the action spectrum of the photocurrent in the external circuit was found to correspond to the absorbance spectra of reaction-center film and solution. It is concluded that charge separation generated across the reaction-center molecule as a result of the primary photochemistry of photosynthesis can be coupled directly to semiconductor electrodes and used to generate photoeffects in an external circuit.

  11. Production of Hydrogen for Clean and Renewable Source of Energy for Fuel Cell Vehicles

    SciTech Connect

    Deng, Xunming; Ingler, William B, Jr.; Abraham, Martin; Castellano, Felix; Coleman, Maria; Collins, Robert; Compaan, Alvin; Giolando, Dean; Jayatissa, Ahalapitiya. H.; Stuart, Thomas; Vonderembse, Mark

    2008-10-31

    This was a two-year project that had two major components: 1) the demonstration of a PV-electrolysis system that has separate PV system and electrolysis unit and the hydrogen generated is to be used to power a fuel cell based vehicle; 2) the development of technologies for generation of hydrogen through photoelectrochemical process and bio-mass derived resources. Development under this project could lead to the achievement of DOE technical target related to PEC hydrogen production at low cost. The PEC part of the project is focused on the development of photoelectrochemical hydrogen generation devices and systems using thin-film silicon based solar cells. Two approaches are taken for the development of efficient and durable photoelectrochemical cells; 1) An immersion-type photoelectrochemical cells (Task 3) where the photoelectrode is immersed in electrolyte, and 2) A substrate-type photoelectrochemical cell (Task 2) where the photoelectrode is not in direct contact with electrolyte. Four tasks are being carried out: Task 1: Design and analysis of DC voltage regulation system for direct PV-to-electrolyzer power feed Task 2: Development of advanced materials for substrate-type PEC cells Task 3: Development of advanced materials for immersion-type PEC cells Task 4: Hydrogen production through conversion of biomass-derived wastes

  12. Nitrogen and cobalt co-doped zinc oxide nanowires - Viable photoanodes for hydrogen generation via photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Patel, Prasad Prakash; Hanumantha, Prashanth Jampani; Velikokhatnyi, Oleg I.; Datta, Moni Kanchan; Hong, Daeho; Gattu, Bharat; Poston, James A.; Manivannan, Ayyakkannu; Kumta, Prashant N.

    2015-12-01

    Photoelectrochemical (PEC) water splitting has been considered as a promising and environmentally benign approach for efficient and economic hydrogen generation by utilization of solar energy. Development of semiconductor materials with low band gap, high photoelectrochemical activity and stability has been of particular interest for a viable PEC water splitting system. In this study, Co doped ZnO, .i.e., (Zn0.95Co0.05)O nanowires (NWs) was selected as the composition for further co-doping with nitrogen by comparing solar to hydrogen efficiency (SHE) of ZnO NWs with that of various compositions of (Zn1-xCox)O NWs (x = 0, 0.05, 0.1). Furthermore, nanostructured vertically aligned Co and N-doped ZnO, .i.e., (Zn1-xCox)O:N NWs (x = 0.05) have been studied as photoanodes for PEC water splitting. An optimal SHE of 1.39% the highest reported so far to the best of our knowledge for ZnO based photoanodes was obtained for the co-doped NWs, (Zn0.95Co0.05)O:N - 600 NWs generated at 600 °C in ammonia atmosphere. Further, (Zn0.95Co0.05)O:N-600 NWs exhibited excellent photoelectrochemical stability under illumination compared to pure ZnO NWs. These promising results suggest the potential of (Zn0.95Co0.05)O:N-600 NWs as a viable photoanode in PEC water splitting cell. Additionally, theoretical first principles study conducted explains the beneficial effects of Co and N co-doping on both, the electronic structure and the band gap of ZnO.

  13. A visible light photoelectrochemical biosensor coupling enzyme-inhibition for organophosphates monitoring based on a dual-functional Cd(0.5)Zn(0.5)S-reduced graphene oxide nanocomposite.

    PubMed

    Liu, Qian; Cai, Jianrong; Huan, Juan; Dong, Xiaoya; Wang, Chengke; Qiu, Baijing; Wang, Kun

    2014-03-01

    A novel visible light photoelectrochemical (PEC) platform coupled with enzyme-inhibition for rapid and sensitive determination of organophosphates (OPs) was constructed based on a dual-functional Cd0.5Zn0.5S-reduced graphene oxide (Cd0.5Zn0.5S-rGO) nanocomposite. Due to the inherent biocompatibility of the Cd0.5Zn0.5S-rGO nanocomposite, acetylcholinesterase (AChE) immobilized on the Cd0.5Zn0.5S-rGO modified electrode can hydrolyze acetylthiocholine chloride into thiocholine, which could increase the photocurrent of the enzyme electrode, and the further inhibition of OPs on the enzyme electrode could decrease the photocurrent response. Based on the notable change in the PEC response of the AChE-Cd0.5Zn0.5S-rGO modified electrode and using Dursban as a model, a simple and effective way for PEC monitoring of OPs is proposed, which showed a wide linear range of 0.001-1 μg mL(-1) with a low detection limit of 0.3 ng mL(-1) (S/N = 3). Moreover, the biosensor was successfully challenged with water samples, demonstrating a new method for rapid and sensitive screening/evaluating exposure to organophosphorus pesticides and other hazardous substances.

  14. Critical Research for Cost-Effective Photoelectrochemical Production of Hydrogen

    SciTech Connect

    Xu, Liwei; Deng, Xunming; Abken, Anka; Cao, Xinmin; Du, Wenhui; Vijh, Aarohi; Ingler, William; Chen, Changyong; Fan, Qihua; Collins, Robert; Compaan, Alvin; Yan, Yanfa; Giolando, Dean; Turner, John

    2014-10-29

    The objective of this project is to develop critical technologies required for cost-effective production of hydrogen from sunlight and water using a-Si triple junction solar cell based photo-electrodes. In this project, Midwest Optoelectronics, LLC (MWOE) and its collaborating organizations utilize triple junction a-Si thin film solar cells as the core element to fabricate photoelectrochemical (PEC) cells. Triple junction a-Si/a-SiGe/a-SiGe solar cell is an ideal material for making cost-effective PEC system which uses sun light to split water and generate hydrogen. It has the following key features: 1) It has an open circuit voltage (Voc ) of ~ 2.3V and has an operating voltage around 1.6V. This is ideal for water splitting. There is no need to add a bias voltage or to inter-connect more than one solar cell. 2) It is made by depositing a-Si/a-SiGe/aSi-Ge thin films on a conducting stainless steel substrate which can serve as an electrode. When we immerse the triple junction solar cells in an electrolyte and illuminate it under sunlight, the voltage is large enough to split the water, generating oxygen at the Si solar cell side (for SS/n-i-p/sunlight structure) and hydrogen at the back, which is stainless steel side. There is no need to use a counter electrode or to make any wire connection. 3) It is being produced in large rolls of 3ft wide and up to 5000 ft long stainless steel web in a 25MW roll-to-roll production machine. Therefore it can be produced at a very low cost. After several years of research with many different kinds of material, we have developed promising transparent, conducting and corrosion resistant (TCCR) coating material; we carried out extensive research on oxygen and hydrogen generation catalysts, developed methods to make PEC electrode from production-grade a-Si solar cells; we have designed and tested various PEC module cases and carried out extensive outdoor testing; we were able to obtain a solar to hydrogen conversion efficiency (STH

  15. Solid polymer electrolyte photovoltaic cell

    SciTech Connect

    Skotheim, T.; Lundstrom, I.

    1982-04-01

    Solid photoelectrochemical cells are described based on PEO-KI/I/sub 2/ electrolytes, n-Si/Pt/PPy photoanodes, and conductive tin-oxide glass counter electrodes. The performance of the present devices is limited by a high series resistance in the polymer film. 22 refs.

  16. Label-free photoelectrochemical strategy for hairpin DNA hybridization detection on titanium dioxide electrode

    SciTech Connect

    Lu Wu; Wang Geng; Jin Yan; Yao Xin; Hu Jianqiang; Li Jinghong

    2006-12-25

    A new photoelectrochemical strategy for hairpin DNA hybridization was devised, in which TiO{sub 2} served as the anchor and signal transducer, and no label or redox couples were required. Once the hybridization between hairpin DNA probe and target DNA occurred, the photocurrent would decrease, utilizing which the sequence of the target DNA could be identified. The sequence specificity experiment showed that one or more mismatches of DNA bases could be discriminated. This photoelectrochemical method would be a potential tool in DNA hybridization detection due to its great advantages: label-free, high sensitivity, specific recognition, low cost, and easy fabrication.

  17. Enhanced photoelectrochemical strategy for ultrasensitive DNA detection based on two different sizes of CdTe quantum dots cosensitized TiO2/CdS:Mn hybrid structure.

    PubMed

    Fan, Gao-Chao; Han, Li; Zhang, Jian-Rong; Zhu, Jun-Jie

    2014-11-01

    A TiO2/CdS:Mn hybrid structure cosensitized with two different sizes of CdTe quantum dots (QDs) was designed to develop a novel and ultrasensitive photoelectrochemical DNA assay. In this protocol, TiO2/CdS:Mn hybrid structure was prepared by successive adsorption and reaction of Cd(2+)/Mn(2+) and S(2-) ions on the surface of TiO2 film and then was employed as matrix for immobilization of hairpin DNA probe, whereas large-sized CdTe-COOH QDs and small-sized CdTe-NH2 QDs as signal amplification elements were successively labeled on the terminal of hairpin DNA probe. The target DNA detection was based upon the photocurrent change originated from conformation change of the hairpin DNA probe after hybridization with target DNA. In the absence of target DNA, the immobilized DNA probe was in the hairpin form and the anchored different sizes of CdTe-COOH and CdTe-NH2 QDs were close to the TiO2/CdS:Mn electrode surface, which led to a very strong photocurrent intensity because of the formation of the cosensitized structure. However, in the presence of target DNA, the hairpin DNA probe hybridized with target DNA and changed into a more rigid, rodlike double helix, which forced the multianchored CdTe QDs away from the TiO2/CdS:Mn electrode surface, resulting in significantly decreased photocurrent intensity because of the vanished cosensitization effect. By using this cosensitization signal amplification strategy, the proposed DNA assay could offer an ultrasensitive and specific detection of DNA down to 27 aM, and it opened up a new promising platform to detect various DNA targets at ultralow levels for early diagnoses of different diseases. PMID:25294102

  18. A Novel Photoelectrochemical Biosensor for Tyrosinase and Thrombin Detection.

    PubMed

    Chen, Jiexia; Liu, Yifan; Zhao, Guang-Chao

    2016-01-01

    A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the other end and a cleavage site recognized by thrombin between them was designed. The designed peptide can be fixed on surface of the CdTe quantum dots (QDs)-modified indium-tin oxide (ITO) electrode through electrostatic attraction to construct the photoelectrochemical biosensor. The tyrosinase target can catalyze the oxidization of tyrosine by oxygen into ortho-benzoquinone residues, which results in a decrease in the sensor photocurrent. Subsequently, the cleavage site could be recognized and cut off by another thrombin target, restoring the sensor photocurrent. The decrease or increase of photocurrent in the sensor enables us to assay tyrosinase and thrombin. Thus, the detection of tyrosinase and thrombin can be achieved in the linear range from 2.6 to 32 μg/mL and from 4.5 to 100 μg/mL with detection limits of 1.5 μg/mL and 1.9 μg/mL, respectively. Most importantly, this strategy shall allow us to detect different classes of enzymes simultaneously by designing various enzyme-specific peptide substrates. PMID:26805846

  19. A Novel Photoelectrochemical Biosensor for Tyrosinase and Thrombin Detection.

    PubMed

    Chen, Jiexia; Liu, Yifan; Zhao, Guang-Chao

    2016-01-21

    A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the other end and a cleavage site recognized by thrombin between them was designed. The designed peptide can be fixed on surface of the CdTe quantum dots (QDs)-modified indium-tin oxide (ITO) electrode through electrostatic attraction to construct the photoelectrochemical biosensor. The tyrosinase target can catalyze the oxidization of tyrosine by oxygen into ortho-benzoquinone residues, which results in a decrease in the sensor photocurrent. Subsequently, the cleavage site could be recognized and cut off by another thrombin target, restoring the sensor photocurrent. The decrease or increase of photocurrent in the sensor enables us to assay tyrosinase and thrombin. Thus, the detection of tyrosinase and thrombin can be achieved in the linear range from 2.6 to 32 μg/mL and from 4.5 to 100 μg/mL with detection limits of 1.5 μg/mL and 1.9 μg/mL, respectively. Most importantly, this strategy shall allow us to detect different classes of enzymes simultaneously by designing various enzyme-specific peptide substrates.

  20. A Novel Photoelectrochemical Biosensor for Tyrosinase and Thrombin Detection

    PubMed Central

    Chen, Jiexia; Liu, Yifan; Zhao, Guang-Chao

    2016-01-01

    A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the other end and a cleavage site recognized by thrombin between them was designed. The designed peptide can be fixed on surface of the CdTe quantum dots (QDs)-modified indium-tin oxide (ITO) electrode through electrostatic attraction to construct the photoelectrochemical biosensor. The tyrosinase target can catalyze the oxidization of tyrosine by oxygen into ortho-benzoquinone residues, which results in a decrease in the sensor photocurrent. Subsequently, the cleavage site could be recognized and cut off by another thrombin target, restoring the sensor photocurrent. The decrease or increase of photocurrent in the sensor enables us to assay tyrosinase and thrombin. Thus, the detection of tyrosinase and thrombin can be achieved in the linear range from 2.6 to 32 μg/mL and from 4.5 to 100 μg/mL with detection limits of 1.5 μg/mL and 1.9 μg/mL, respectively. Most importantly, this strategy shall allow us to detect different classes of enzymes simultaneously by designing various enzyme-specific peptide substrates. PMID:26805846

  1. Dye-sensitized PS-b-P2VP-templated nickel oxide films for photoelectrochemical applications

    PubMed Central

    Massin, Julien; Bräutigam, Maximilian; Kaeffer, Nicolas; Queyriaux, Nicolas; Field, Martin J.; Schacher, Felix H.; Popp, Jürgen; Chavarot-Kerlidou, Murielle; Dietzek, Benjamin; Artero, Vincent

    2015-01-01

    Moving from homogeneous water-splitting photocatalytic systems to photoelectrochemical devices requires the preparation and evaluation of novel p-type transparent conductive photoelectrode substrates. We report here on the sensitization of polystyrene-block-poly-(2-vinylpyridine) (PS-b-P2VP) diblock copolymer-templated NiO films with an organic push–pull dye. The potential of these new templated NiO film preparations for photoelectrochemical applications is compared with NiO material templated by F108 triblock copolymers. We conclude that NiO films are promising materials for the construction of dye-sensitized photocathodes to be inserted into photoelectrochemical (PEC) cells. However, a combined effort at the interface between materials science and molecular chemistry, ideally funded within a Global Artificial Photosynthesis Project, is still needed to improve the overall performance of the photoelectrodes and progress towards economically viable PEC devices. PMID:26052420

  2. Semiconductor Nanowires for Photoelectrochemical Water Splitting

    NASA Astrophysics Data System (ADS)

    Hwang, Yun Jeong

    Photolysis of water with semiconductor materials has been investigated intensely as a clean and renewable energy resource by storing solar energy in chemical bonds such as hydrogen. One-dimensional (1D) nanostructures such as nanowires can provide several advantages for photoelectrochemical (PEC) water splitting due to their high surface areas and excellent charge transport and collection efficiency. This dissertation discusses various nanowire photoelectrodes for single or dual semiconductor systems, and their linked PEC cells for self-driven water splitting. After an introduction of solar water splitting in the first chapter, the second chapter demonstrates water oxidative activities of hydrothermally grown TiO2 nanowire arrays depending on their length and surface properties. The photocurrents with TiO2 nanowire arrays approach saturation due to their poor charge collection efficiency with longer nanowires despite increased photon absorption efficiency. Epitaxial grains of rutile atomic layer deposition (ALD) shell on TiO2 nanowire increase the photocurrent density by 1.5 times due to improved charge collection efficiency especially in the short wavelength region. Chapter three compares the photocurrent density of the planar Si and Si nanowire arrays coated by anatase ALD TiO 2 thin film as a model system of a dual bandgap system. The electroless etched Si nanowire coated by ALD TiO2 (Si EENW/TiO2) shows 2.5 times higher photocurrent density due to lower reflectance and higher surface area. Also, this chapter illustrates that n-Si/n-TiO2 heterojunction is a promising structure for the photoanode application of a dual semiconductor system, since it can enhance the photocurrent density compared to p-Si/n-TiO 2 junction with the assistance of bend banding at the interface. Chapter four demonstrates the charge separation and transport of photogenerated electrons and holes within a single asymmetric Si/TiO2 nanowire. Kelvin probe force microscopy measurements show

  3. Novel nanostructure zinc zirconate, zinc oxide or zirconium oxide pastes coated on fluorine doped tin oxide thin film as photoelectrochemical working electrodes for dye-sensitized solar cell.

    PubMed

    Hossein Habibi, Mohammad; Askari, Elham; Habibi, Mehdi; Zendehdel, Mahmoud

    2013-03-01

    Zinc zirconate (ZnZrO(3)) (ZZ), zinc oxide (ZnO) (ZO) and zirconium oxide (ZrO(2)) (ZRO) nano-particles were synthesized by simple sol-gel method. ZZ, ZO and ZRO nano-particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectrum (DRS). Nanoporous ZZ, ZO and ZRO thin films were prepared doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in dye sensitized solar cells (DSSC). Their photovoltaic behavior were compared with standard using D35 dye and an electrolyte containing [Co(bpy)(3)](PF(6))(2), [Co(pby)(3)](PF(6))(3), LiClO(4), and 4-tert-butylpyridine (TBP). The properties of DSSC have been studied by measuring their short-circuit photocurrent density (Jsc), open-circuit voltage (VOC) and fill factor (ff). The application of ZnZrO(3) as working electrode produces a significant improvement in the fill factor (ff) of the dye-sensitized solar cells (ff=56%) compared to ZnO working electrode (ff=40%) under the same condition.

  4. Ultrasensitive photoelectrochemical immunoassay for CA19-9 detection based on CdSe@ZnS quantum dots sensitized TiO2NWs/Au hybrid structure amplified by quenching effect of Ab2@V(2+) conjugates.

    PubMed

    Zhu, Hua; Fan, Gao-Chao; Abdel-Halim, E S; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-03-15

    A novel, enhanced photoelectrochemical immunoassay was established for sensitive and specific detection of carbohydrate antigen 19-9 (CA19-9, Ag). In this protocol, TiO2 nanowires (TiO2NWs) were first decorated with Au nanoparticles to form TiO2NWs/Au hybrid structure, and then coated with CdSe@ZnS quantum dots (QDs) via the layer-by-layer method, producing TiO2NWs/Au/CdSe@ZnS sensitized structure, which was employed as the photoelectrochemical matrix to immobilize capture CA19-9 antibodies (Ab1); whereas, bipyridinium (V(2+)) molecules were labeled on signal CA19-9 antibodies (Ab2) to form Ab2@V(2+) conjugates, which were used as signal amplification elements. The TiO2NWs/Au/CdSe@ZnS sensitized structure could adequately absorb light energy and dramatically depress electron-hole recombination, resulting in evidently enhanced photocurrent intensity of the immunosensing electrode. While target Ag were detected, the Ab2@V(2+) conjugates could significantly decrease the photocurrent detection signal because of strong electron-withdrawing property of V(2+) coupled with evident steric hindrance of Ab2. Thanks to synergy effect of TiO2NWs/Au/CdSe@ZnS sensitized structure and quenching effect of Ab2@V(2+) conjugates, the well-established photoelectrochemical immunoassay exhibited a low detection limit of 0.0039 U/mL with a wide linear range from 0.01 U/mL to 200 U/mL for target Ag detection. This proposed photoelectrochemical protocol also showed good reproducibility, specificity and stability, and might be applied to detect other important biomarkers. PMID:26433066

  5. Ultrasensitive photoelectrochemical immunoassay for CA19-9 detection based on CdSe@ZnS quantum dots sensitized TiO2NWs/Au hybrid structure amplified by quenching effect of Ab2@V(2+) conjugates.

    PubMed

    Zhu, Hua; Fan, Gao-Chao; Abdel-Halim, E S; Zhang, Jian-Rong; Zhu, Jun-Jie

    2016-03-15

    A novel, enhanced photoelectrochemical immunoassay was established for sensitive and specific detection of carbohydrate antigen 19-9 (CA19-9, Ag). In this protocol, TiO2 nanowires (TiO2NWs) were first decorated with Au nanoparticles to form TiO2NWs/Au hybrid structure, and then coated with CdSe@ZnS quantum dots (QDs) via the layer-by-layer method, producing TiO2NWs/Au/CdSe@ZnS sensitized structure, which was employed as the photoelectrochemical matrix to immobilize capture CA19-9 antibodies (Ab1); whereas, bipyridinium (V(2+)) molecules were labeled on signal CA19-9 antibodies (Ab2) to form Ab2@V(2+) conjugates, which were used as signal amplification elements. The TiO2NWs/Au/CdSe@ZnS sensitized structure could adequately absorb light energy and dramatically depress electron-hole recombination, resulting in evidently enhanced photocurrent intensity of the immunosensing electrode. While target Ag were detected, the Ab2@V(2+) conjugates could significantly decrease the photocurrent detection signal because of strong electron-withdrawing property of V(2+) coupled with evident steric hindrance of Ab2. Thanks to synergy effect of TiO2NWs/Au/CdSe@ZnS sensitized structure and quenching effect of Ab2@V(2+) conjugates, the well-established photoelectrochemical immunoassay exhibited a low detection limit of 0.0039 U/mL with a wide linear range from 0.01 U/mL to 200 U/mL for target Ag detection. This proposed photoelectrochemical protocol also showed good reproducibility, specificity and stability, and might be applied to detect other important biomarkers.

  6. Unraveling the photoelectrochemical properties of ionic liquids: cognizance of partially reversible redox activity.

    PubMed

    Patel, Dipal B; Chauhan, Khushbu R; Mukhopadhyay, Indrajit

    2014-11-01

    Ionic liquid based electrolytes are gaining great interest in the field of photoenergy conversion. We have found that the ionic liquids namely BMIm Cl, BMIm PF6 and BMIm Tf2N inherently offer redox activity. The device performance of the photoelectrochemical (PEC) cells of the configuration PbOx (0.25 cm(2))|blank ionic liquids|platinum (2 cm(2)) was analyzed in detail to get insights into the working principle of such systems. It was found that partially reversible redox ion pairs diminish the performance of such cells as power generating devices. The partial redox activity of the ionic liquids was confirmed by a number of observations derived from the PEC spectra. The important parameter, Vredox, which determines the performance of any PEC cell was also calculated for all the ionic liquids. The difficulties that arise in high frequency C-V measurements for ionic liquid systems were overcome by choosing the appropriate probing frequency. The evaluated Vredox of BMIm Cl, BMIm PF6 and BMIm Tf2N ionic liquids was found to be -0.30, -0.20 and -0.78 V (vs. NHE), respectively. This study will be beneficial to understand the role of ionic liquids as redox active electrolyte media in several applications.

  7. Broad Spectrum Photoelectrochemical Diodes for Solar Hydrogen Generation

    SciTech Connect

    Grimes, Craig A.

    2014-11-26

    Under program auspices we have investigated material chemistries suitable for the solar generation of hydrogen by water photoelectrolysis. We have built upon, and extended, our knowledge base on the synthesis and application of TiO2 nanotube arrays, a material architecture that appears ideal for water photoelectrolysis. To date we have optimized, refined, and greatly extended synthesis techniques suitable for achieving highly ordered TiO2 nanotube arrays of given length, wall thickness, pore diameter, and tube-to-tube spacing for use in water photoelectrolysis. We have built upon this knowledge based to achieve visible light responsive, photocorrosion stable n-type and p-type ternary oxide nanotube arrays for use in photoelectrochemical diodes.

  8. Photoelectrochemical generation of hydrogen and electricity from hydrazine hydrate using BiVO4 electrodes.

    PubMed

    Pilli, Satyananda Kishore; Summers, Kodi; Chidambaram, Dev

    2015-06-01

    This study demonstrates solar driven oxidation of hydrazine hydrate and the simultaneous production of hydrogen and electricity in photoelectrochemical cells and photofuel cells, respectively, using a visible light active molybdenum doped BiVO4 photoelectrode. The developed photoelectrodes exhibited tremendous efficiency towards anodic oxidation of hydrous hydrazine with continuous and stable hydrogen evolution at the Pt cathode under benign pH and zero bias conditions. Significantly, the photofuel cell containing hydrazine hydrate fuel has generated electricity with a high open circuit potential of 0.8 V. The presence of bicarbonate ions in the electrolyte has played a significant role in enhancing the kinetics of photoelectrochemical oxidation of hydrazine and improved the hydrogen and electricity generation efficiency thus avoiding the integration of an oxidation electrocatalyst. In addition, molybdenum doped BiVO4 as a possible photoelectrochemical hydrazine sensor has been investigated and the electrode photocurrent was found to be linearly dependent on the concentration of the hydrazine hydrate in the range of 20-90 mM with a correlation coefficient of 0.9936.

  9. Manipulation of charge transfer and transport in plasmonic-ferroelectric hybrids for photoelectrochemical applications

    PubMed Central

    Wang, Zhijie; Cao, Dawei; Wen, Liaoyong; Xu, Rui; Obergfell, Manuel; Mi, Yan; Zhan, Zhibing; Nasori, Nasori; Demsar, Jure; Lei, Yong

    2016-01-01

    Utilizing plasmonic nanostructures for efficient and flexible conversion of solar energy into electricity or fuel presents a new paradigm in photovoltaics and photoelectrochemistry research. In a conventional photoelectrochemical cell, consisting of a plasmonic structure in contact with a semiconductor, the type of photoelectrochemical reaction is determined by the band bending at the semiconductor/electrolyte interface. The nature of the reaction is thus hard to tune. Here instead of using a semiconductor, we employed a ferroelectric material, Pb(Zr,Ti)O3 (PZT). By depositing gold nanoparticle arrays and PZT films on ITO substrates, and studying the photocurrent as well as the femtosecond transient absorbance in different configurations, we demonstrate an effective charge transfer between the nanoparticle array and PZT. Most importantly, we show that the photocurrent can be tuned by nearly an order of magnitude when changing the ferroelectric polarization in PZT, demonstrating a versatile and tunable system for energy harvesting. PMID:26753764

  10. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    NASA Astrophysics Data System (ADS)

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-06-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range.

  11. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode

    PubMed Central

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-01-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range. PMID:27255209

  12. Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode.

    PubMed

    Kawasaki, Seiji; Takahashi, Ryota; Yamamoto, Takahisa; Kobayashi, Masaki; Kumigashira, Hiroshi; Yoshinobu, Jun; Komori, Fumio; Kudo, Akihiko; Lippmaa, Mikk

    2016-01-01

    Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range. PMID:27255209

  13. Manipulation of charge transfer and transport in plasmonic-ferroelectric hybrids for photoelectrochemical applications.

    PubMed

    Wang, Zhijie; Cao, Dawei; Wen, Liaoyong; Xu, Rui; Obergfell, Manuel; Mi, Yan; Zhan, Zhibing; Nasori, Nasori; Demsar, Jure; Lei, Yong

    2016-01-12

    Utilizing plasmonic nanostructures for efficient and flexible conversion of solar energy into electricity or fuel presents a new paradigm in photovoltaics and photoelectrochemistry research. In a conventional photoelectrochemical cell, consisting of a plasmonic structure in contact with a semiconductor, the type of photoelectrochemical reaction is determined by the band bending at the semiconductor/electrolyte interface. The nature of the reaction is thus hard to tune. Here instead of using a semiconductor, we employed a ferroelectric material, Pb(Zr,Ti)O3 (PZT). By depositing gold nanoparticle arrays and PZT films on ITO substrates, and studying the photocurrent as well as the femtosecond transient absorbance in different configurations, we demonstrate an effective charge transfer between the nanoparticle array and PZT. Most importantly, we show that the photocurrent can be tuned by nearly an order of magnitude when changing the ferroelectric polarization in PZT, demonstrating a versatile and tunable system for energy harvesting.

  14. Manipulation of charge transfer and transport in plasmonic-ferroelectric hybrids for photoelectrochemical applications

    NASA Astrophysics Data System (ADS)

    Wang, Zhijie; Cao, Dawei; Wen, Liaoyong; Xu, Rui; Obergfell, Manuel; Mi, Yan; Zhan, Zhibing; Nasori, Nasori; Demsar, Jure; Lei, Yong

    2016-01-01

    Utilizing plasmonic nanostructures for efficient and flexible conversion of solar energy into electricity or fuel presents a new paradigm in photovoltaics and photoelectrochemistry research. In a conventional photoelectrochemical cell, consisting of a plasmonic structure in contact with a semiconductor, the type of photoelectrochemical reaction is determined by the band bending at the semiconductor/electrolyte interface. The nature of the reaction is thus hard to tune. Here instead of using a semiconductor, we employed a ferroelectric material, Pb(Zr,Ti)O3 (PZT). By depositing gold nanoparticle arrays and PZT films on ITO substrates, and studying the photocurrent as well as the femtosecond transient absorbance in different configurations, we demonstrate an effective charge transfer between the nanoparticle array and PZT. Most importantly, we show that the photocurrent can be tuned by nearly an order of magnitude when changing the ferroelectric polarization in PZT, demonstrating a versatile and tunable system for energy harvesting.

  15. A facile strategy to fabricate high-quality single crystalline brookite TiO2 nanoarrays and their photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Choi, Mingi; Yong, Kijung

    2014-10-01

    cells, and the photoelectrochemical properties such as photocurrent density and open circuit voltage were measured in a three-electrode electrochemical cell with TiO2 nanoarrays, Ag/AgCl and a Pt flag as the working, reference and counter electrodes, respectively, incorporating a 0.1 M NaOH electrolyte solution. The fabricated brookite TiO2 nanoarrays exhibited a highly enhanced photocurrent density and a longer electron lifetime compared with anatase TiO2 nanoarrays with similar lengths. Electronic supplementary information (ESI) available: Detailed descriptions of SEM images of TiO2 structures depending on the reaction time and temperatures, how sodium titanate was converted into anatase, a bandgap study based on diffuse reflection measurements and XRD images dependending on the reaction time of synthesizing brookite. See DOI: 10.1039/c4nr04735d

  16. Photoelectrochemical Carbon Dioxide Reduction Using a Nanoporous Ag Cathode.

    PubMed

    Zhang, Yan; Luc, Wesley; Hutchings, Gregory S; Jiao, Feng

    2016-09-21

    Solar fuel production from abundant sources using photoelectrochemical (PEC) systems is an attractive approach to address the challenges associated with the intermittence of solar energy. In comparison to electrochemical systems, PEC cells directly utilize solar energy as the energy input, and if necessary, then an additional external bias can be applied to drive the desired reaction. In this work, a PEC cell composing of a Ni-coated Si photoanode and a nanoporous Ag cathode was developed for CO2 conversion to CO. The thin Ni layer not only protected the Si wafer from photocorrosion but also served as the oxygen evolution catalyst. At an external bias of 2.0 V, the PEC cell delivered a current density of 10 mA cm(-2) with a CO Faradaic efficiency of ∼70%. More importantly, a stable performance up to 3 h was achieved under photoelectrolysis conditions, which is among the best literature-reported performances for PEC CO2 reduction cells. The photovoltage of the PEC cell was estimated to be ∼0.4 V, which corresponded to a 17% energy saving by solar energy utilization. Postreaction structural analysis showed the corrosion of the Ni layer at the Si photoanode/catalyst interface, which caused performance degradation under prolonged operations. A stable oxygen evolution catalyst with a robust interface is crucial to the long-term stability of PEC CO2 reduction cells. PMID:27588723

  17. Photoelectrochemical water splitting: silicon photocathodes for hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Warren, Emily L.; Boettcher, Shannon W.; McKone, James R.; Lewis, Nathan S.

    2010-08-01

    The development of low cost, scalable, renewable energy technologies is one of today's most pressing scientific challenges. We report on progress towards the development of a photoelectrochemical water-splitting system that will use sunlight and water as the inputs to produce renewable hydrogen with oxygen as a by-product. This system is based on the design principle of incorporating two separate, photosensitive inorganic semiconductor/liquid junctions to collectively generate the 1.7-1.9 V at open circuit needed to support both the oxidation of H2O (or OH-) and the reduction of H+ (or H2O). Si microwire arrays are a promising photocathode material because the high aspect-ratio electrode architecture allows for the use of low cost, earth-abundant materials without sacrificing energy-conversion efficiency, due to the orthogonalization of light absorption and charge-carrier collection. Additionally, the high surfacearea design of the rod-based semiconductor array inherently lowers the flux of charge carriers over the rod array surface relative to the projected geometric surface of the photoelectrode, thus lowering the photocurrent density at the solid/liquid junction and thereby relaxing the demands on the activity (and cost) of any electrocatalysts. Arrays of Si microwires grown using the Vapor Liquid Solid (VLS) mechanism have been shown to have desirable electronic light absorption properties. We have demonstrated that these arrays can be coated with earth-abundant metallic catalysts and used for photoelectrochemical production of hydrogen. This development is a step towards the demonstration of a complete artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, and scalable.

  18. Self bleaching photoelectrochemical-electrochromic device

    DOEpatents

    Bechinger, Clemens S.; Gregg, Brian A.

    2002-04-09

    A photoelectrochemical-electrochromic device comprising a first transparent electrode and a second transparent electrode in parallel, spaced relation to each other. The first transparent electrode is electrically connected to the second transparent electrode. An electrochromic material is applied to the first transparent electrode and a nanoporous semiconductor film having a dye adsorbed therein is applied to the second transparent electrode. An electrolyte layer contacts the electrochromic material and the nanoporous semiconductor film. The electrolyte layer has a redox couple whereby upon application of light, the nanoporous semiconductor layer dye absorbs the light and the redox couple oxidizes producing an electric field across the device modulating the effective light transmittance through the device.

  19. Microcontact-printing-assisted access of graphitic carbon nitride films with favorable textures toward photoelectrochemical application.

    PubMed

    Liu, Jian; Wang, Hongqiang; Chen, Zu Peng; Moehwald, Helmuth; Fiechter, Sebastian; van de Krol, Roel; Wen, Liping; Jiang, Lei; Antonietti, Markus

    2015-01-27

    An "ink" (cyanamide) infiltrated anodic aluminum oxide (AAO) stamp is found capable of printing carbon nitride films featuring regular microstructures of the stamp onto the substrates via in situ "chemical vapor deposition". A photocurrent density of 30.2 μA cm(-2 --) at 1.23 VRHE is achieved for a film on a conductive substrate, which is so far the highest value for pure carbon nitride based photoelectrochemical devices.

  20. Enzymatic Oxydate-Triggered Self-Illuminated Photoelectrochemical Sensing Platform for Portable Immunoassay Using Digital Multimeter.

    PubMed

    Shu, Jian; Qiu, Zhenli; Zhou, Qian; Lin, Youxiu; Lu, Minghua; Tang, Dianping

    2016-03-01

    Herein a novel split-type photoelectrochemical (PEC) immunosensing platform was designed for sensitive detection of low-abundance biomarkers (prostate-specific antigen, PSA, used in this case) by coupling a peroxyoxalate chemiluminescence (PO-CL) self-illuminated system with digital multimeter (DMM) readout. The PEC detection device consisted of a capacitor/DMM-joined electronic circuit and a PO-CL-based self-illuminated cell. Initially, reduced graphene oxide-doped BiVO4 (BiVO4-rGO) photovoltaic materials with good photoelectric properties was integrated into the capacitor/DMM-joined circuit for photocurrent generation in the presence of hydrogen peroxide (H2O2, as the hole-trapping reagent). A sandwich-type immunoreaction with target PSA was carried out in capture antibody-coated microplates by using glucose oxidase/detection antibody-conjugating gold nanoparticle (pAb2-AuNP-GOx). Accompanying the sandwiched immunocomplex, the labeled GOx could oxidize glucose to produce H2O2. The as-generated H2O2 could act as the coreaction reagent to trigger the chemiluminescence of the peroxyoxalate system and the PEC reaction of the BiVO4-rGO. Meanwhile, the self-illuminated light could induce photovoltaic material (BiVO4-rGO) to produce a voltage that was utilized to charge an external capacitor. With the switch closed, the capacitor could discharge through the DMM and provide an instantaneous current. Different from conventional PEC immunoassays, the as-generated photoelectron was stored in the capacitor and released instantaneously to amplify the photocurrent. Under the optimal conditions, the transient current increased with the increasing target PSA concentration in the dynamic working range from 10 pg mL(-1) to 80 ng mL(-1) with a detection limit (LOD) of 3 pg mL(-1). This work demonstrated for the first time that the peroxyoxalate CL system could be used as a suitable substitute of physical light source to apply in PEC immunoassay. In addition, this methodology

  1. Enzymatic Oxydate-Triggered Self-Illuminated Photoelectrochemical Sensing Platform for Portable Immunoassay Using Digital Multimeter.

    PubMed

    Shu, Jian; Qiu, Zhenli; Zhou, Qian; Lin, Youxiu; Lu, Minghua; Tang, Dianping

    2016-03-01

    Herein a novel split-type photoelectrochemical (PEC) immunosensing platform was designed for sensitive detection of low-abundance biomarkers (prostate-specific antigen, PSA, used in this case) by coupling a peroxyoxalate chemiluminescence (PO-CL) self-illuminated system with digital multimeter (DMM) readout. The PEC detection device consisted of a capacitor/DMM-joined electronic circuit and a PO-CL-based self-illuminated cell. Initially, reduced graphene oxide-doped BiVO4 (BiVO4-rGO) photovoltaic materials with good photoelectric properties was integrated into the capacitor/DMM-joined circuit for photocurrent generation in the presence of hydrogen peroxide (H2O2, as the hole-trapping reagent). A sandwich-type immunoreaction with target PSA was carried out in capture antibody-coated microplates by using glucose oxidase/detection antibody-conjugating gold nanoparticle (pAb2-AuNP-GOx). Accompanying the sandwiched immunocomplex, the labeled GOx could oxidize glucose to produce H2O2. The as-generated H2O2 could act as the coreaction reagent to trigger the chemiluminescence of the peroxyoxalate system and the PEC reaction of the BiVO4-rGO. Meanwhile, the self-illuminated light could induce photovoltaic material (BiVO4-rGO) to produce a voltage that was utilized to charge an external capacitor. With the switch closed, the capacitor could discharge through the DMM and provide an instantaneous current. Different from conventional PEC immunoassays, the as-generated photoelectron was stored in the capacitor and released instantaneously to amplify the photocurrent. Under the optimal conditions, the transient current increased with the increasing target PSA concentration in the dynamic working range from 10 pg mL(-1) to 80 ng mL(-1) with a detection limit (LOD) of 3 pg mL(-1). This work demonstrated for the first time that the peroxyoxalate CL system could be used as a suitable substitute of physical light source to apply in PEC immunoassay. In addition, this methodology

  2. Photo-electrochemical studies of chemically deposited nanocrystalline meso-porous n-type TiO2 thin films for dye-sensitized solar cell (DSSC) using simple synthesized azo dye

    NASA Astrophysics Data System (ADS)

    Ezema, C. G.; Nwanya, A. C.; Ezema, B. E.; Patil, B. H.; Bulakhe, R. N.; Ukoha, P. O.; Lokhande, C. D.; Maaza, Malik; Ezema, Fabian I.

    2016-04-01

    Nanocrystalline titanium dioxide (TiO2) thin films were deposited by successive ionic layer adsorption and reaction method onto fluorine doped tin oxide coated glass substrate at room temperature (300 K). Titanium trichloride and sodium hydroxide were used as cationic and anionic sources, respectively. The as-deposited and annealed films were characterized for structural, morphological, optical, electrical and wettability properties. The photoelectrochemical study of TiO2 sensitized with a laboratory synthesized organic dye (azo) was evaluated in the polyiodide electrolyte at 40 mW cm-2 light illumination intensity. The photovoltaic characteristics show a fill factor of 0.24 and solar conversion efficiency value of 0.032 % for a TiO2 thickness of 0.96 µm as compared to efficiency of 0.014 % for rose Bengal of the same thickness.

  3. Spectral sensitization of nanocrystalline solar cells

    DOEpatents

    Spitler, Mark T.; Ehret, Anne; Stuhl, Louis S.

    2002-01-01

    This invention relates to dye sensitized polycrystalline photoelectrochemical solar cells for use in energy transduction from light to electricity. It concerns the utility of highly absorbing organic chromophores as sensitizers in such cells and the degree to which they may be utilized alone and in combination to produce an efficient photoelectrochemical cell, e.g., a regenerative solar cell.

  4. Directed Assembly of Nanoparticle Catalysts on Nanowire Photoelectrodes for Photoelectrochemical CO2 Reduction.

    PubMed

    Kong, Qiao; Kim, Dohyung; Liu, Chong; Yu, Yi; Su, Yude; Li, Yifan; Yang, Peidong

    2016-09-14

    Reducing carbon dioxide with a multicomponent artificial photosynthetic system, closely mimicking nature, represents a promising approach for energy storage. Previous works have focused on exploiting light-harvesting semiconductor nanowires (NW) for photoelectrochemical water splitting. With the newly developed CO2 reduction nanoparticle (NP) catalysts, direct interfacing of these nanocatalysts with NW light absorbers for photoelectrochemical reduction of CO2 becomes feasible. Here, we demonstrate a directed assembly of NP catalysts on vertical NW substrates for CO2-to-CO conversion under illumination. Guided by the one-dimensional geometry, well-dispersed assembly of Au3Cu NPs on the surface of Si NW arrays was achieved with facile coverage tunability. Such Au3Cu NP decorated Si NW arrays can readily serve as effective CO2 reduction photoelectrodes, exhibiting high CO2-to-CO selectivity close to 80% at -0.20 V vs RHE with suppressed hydrogen evolution. A reduction of 120 mV overpotential compared to the planar (PL) counterpart was observed resulting from the optimized spatial arrangement of NP catalysts on the high surface area NW arrays. In addition, this system showed consistent photoelectrochemical CO2 reduction capability up to 18 h. This simple photoelectrode assembly process will lead to further progress in artificial photosynthesis, by allowing the combination of developments in each subfield to create an efficient light-driven system generating carbon-based fuels. PMID:27494433

  5. Surface Engineered Doping of Hematite Nanorod Arrays for Improved Photoelectrochemical Water Splitting

    PubMed Central

    Shen, Shaohua; Zhou, Jigang; Dong, Chung-Li; Hu, Yongfeng; Tseng, Eric Nestor; Guo, Penghui; Guo, Liejin; Mao, Samuel S.

    2014-01-01

    Given the narrow band gap enabling excellent optical absorption, increased charge carrier density and accelerated surface oxidation reaction kinetics become the key points for improved photoelectrochemical performances for water splitting over hematite (α-Fe2O3) photoanodes. In this study, a facile and inexpensive method was demonstrated to develop core/shell structured α-Fe2O3 nanorod arrays. A thin, Ag-doped overlayer of ~2–3 nm thickness was formed along α-Fe2O3 nanorods via ultrasonication treatment of solution-based β-FeOOH nanorods in Ag precursor solution followed by high temperature annealing. The obtained α-Fe2O3/AgxFe2−xO3 core/shell nanorod films demonstrated much higher photoelectrochemical performances as photoanodes than the pristine α-Fe2O3 nanorod film, especially in the visible light region; the incident photon-to-current efficiency (IPCE) at 400 nm was increased from 2.2% to 8.4% at 1.23 V vs. RHE (Reversible hydrogen electrode). Mott-Schottky analysis and X-ray absorption spectra revealed that the Ag-doped overlayer not only increased the carrier density in the near-surface region but also accelerated the surface oxidation reaction kinetics, synergistically contributing to the improved photoelectrochemical performances. These findings provide guidance for the design and optimization of nanostructured photoelectrodes for efficient solar water splitting. PMID:25316219

  6. CdS-graphene Nanocomposite for Efficient Visible-light-driven Photocatalytic and Photoelectrochemical Applications.

    PubMed

    Khan, Mohammad Ehtisham; Khan, Mohammad Mansoob; Cho, Moo Hwan

    2016-11-15

    This paper reports cadmium sulphide nanoparticles-(CdS NPs)-graphene nanocomposite (CdS-Graphene), prepared by a simple method, in which CdS NPs were anchored/decorated successfully onto graphene sheets. The as-synthesized nanocomposite was characterized using standard characterization techniques. A combination of CdS NPs with the optimal amount of two-dimensional graphene sheets had a profound influence on the properties of the resulting hybrid nanocomposite, such as enhanced optical, photocatalytic, and photo-electronic properties. The photocatalytic degradation ability of the CdS-Graphene nanocomposite was evaluated by degrading different types of dyes in the dark and under visible light irradiation. Furthermore, the photoelectrode performance of the nanocomposite was evaluated by different electrochemical techniques. The results showed that the CdS-Graphene nanocomposite can serve as an efficient visible-light-driven photocatalyst as well as photoelectrochemical performance for optoelectronic applications. The significantly enhanced photocatalytic and photoelectrochemical performance of the CdS-Graphene nanocomposite was attributed to the synergistic effects of the enhanced light absorption behaviour and high electron conductivity of the CdS NPs and graphene sheets, which facilitates charge separation and lengthens the lifetime of photogenerated electron-hole pairs by reducing the recombination rate. The as-synthesized narrow band gap CdS-Graphene nanocomposite can be used for wide range of visible light-induced photocatalytic and photoelectrochemical based applications. PMID:27505275

  7. Development & Optimization of Materials and Processes for a Cost Effective Photoelectrochemical Hydrogen Production System. Final report

    SciTech Connect

    McFarland, Eric W

    2011-01-17

    The overall project objective was to apply high throughput experimentation and combinatorial methods together with novel syntheses to discover and optimize efficient, practical, and economically sustainable materials for photoelectrochemical production of bulk hydrogen from water. Automated electrochemical synthesis and photoelectrochemical screening systems were designed and constructed and used to study a variety of new photoelectrocatalytic materials. We evaluated photocatalytic performance in the dark and under illumination with or without applied bias in a high-throughput manner and did detailed evaluation on many materials. Significant attention was given to -Fe2O3 based semiconductor materials and thin films with different dopants were synthesized by co-electrodeposition techniques. Approximately 30 dopants including Al, Zn, Cu, Ni, Co, Cr, Mo, Ti, Pt, etc. were investigated. Hematite thin films doped with Al, Ti, Pt, Cr, and Mo exhibited significant improvements in efficiency for photoelectrochemical water splitting compared with undoped hematite. In several cases we collaborated with theorists who used density functional theory to help explain performance trends and suggest new materials. The best materials were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visual spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS). The photoelectrocatalytic performance of the thin films was evaluated and their incident photon

  8. Directed Assembly of Nanoparticle Catalysts on Nanowire Photoelectrodes for Photoelectrochemical CO2 Reduction.

    PubMed

    Kong, Qiao; Kim, Dohyung; Liu, Chong; Yu, Yi; Su, Yude; Li, Yifan; Yang, Peidong

    2016-09-14

    Reducing carbon dioxide with a multicomponent artificial photosynthetic system, closely mimicking nature, represents a promising approach for energy storage. Previous works have focused on exploiting light-harvesting semiconductor nanowires (NW) for photoelectrochemical water splitting. With the newly developed CO2 reduction nanoparticle (NP) catalysts, direct interfacing of these nanocatalysts with NW light absorbers for photoelectrochemical reduction of CO2 becomes feasible. Here, we demonstrate a directed assembly of NP catalysts on vertical NW substrates for CO2-to-CO conversion under illumination. Guided by the one-dimensional geometry, well-dispersed assembly of Au3Cu NPs on the surface of Si NW arrays was achieved with facile coverage tunability. Such Au3Cu NP decorated Si NW arrays can readily serve as effective CO2 reduction photoelectrodes, exhibiting high CO2-to-CO selectivity close to 80% at -0.20 V vs RHE with suppressed hydrogen evolution. A reduction of 120 mV overpotential compared to the planar (PL) counterpart was observed resulting from the optimized spatial arrangement of NP catalysts on the high surface area NW arrays. In addition, this system showed consistent photoelectrochemical CO2 reduction capability up to 18 h. This simple photoelectrode assembly process will lead to further progress in artificial photosynthesis, by allowing the combination of developments in each subfield to create an efficient light-driven system generating carbon-based fuels.

  9. Graphene oxide modified TiO2 nanotube arrays: enhanced visible light photoelectrochemical properties

    SciTech Connect

    Song, Peng; Zhang, Xiaoyan; Sun, Mingxuan; Cui, Xiaoli; Lin, Yuehe

    2012-01-01

    Novel nanocomposite films based on graphene oxide (GO) and TiO2 nanotube arrays were synthesized by assembling GO on the surface of self-organized TiO2 nanotube arrays through a simple assembling method. The composite films were characterized with field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and UV-vis diffuse reflectance spectroscopy. Photoelectrochemical properties of the composite nanotube arrays were investigated under visible light illumination. Remarkably enhanced visible light photoelectrochemical response was observed for the GO decorated TiO2 nanotube composite electrode compared with pristine TiO2 nanotube arrays. Sensitizing effect of GO on the photoelectrochemical response of TiO2 nanotube arrays was demonstrated and about 15 times enhanced maximum photoconversion efficiency was obtained with the presence of GO. Enhanced photocatalytic activity of TiO2 nanotube arrays towards degradation of methyl blue was also demonstrated after modification of GO. The results presented here demonstrate GO to be efficient for the improvement of utilization of visible light for TiO2 nanotube arrays.

  10. Graphene oxide modified TiO2 nanotube arrays: enhanced visible light photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Song, Peng; Zhang, Xiaoyan; Sun, Mingxuan; Cui, Xiaoli; Lin, Yuehe

    2012-02-01

    Novel nanocomposite films, based on graphene oxide (GO) and TiO2 nanotube arrays, were synthesized by assembling GO on the surface of self-organized TiO2 nanotube arrays through a simple impregnation method. The composite films were characterized with field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and UV-vis diffuse reflectance spectroscopy. The photoelectrochemical properties of the composite nanotube arrays were investigated under visible light illumination. Remarkably enhanced visible light photoelectrochemical response was observed for the GO decorated TiO2 nanotube composite electrode compared with pristine TiO2 nanotube arrays. The sensitizing effect of GO on the photoelectrochemical response of the TiO2 nanotube arrays was demonstrated and about 15 times enhanced maximum photoconversion efficiency was obtained with the presence of GO. An enhanced photocatalytic activity of the TiO2 nanotube arrays towards the degradation of methyl blue was also demonstrated after modification with GO. The results presented here demonstrate GO to be efficient for the improved utilization of visible light for TiO2 nanotube arrays.

  11. Graphene oxide modified TiO2 nanotube arrays: enhanced visible light photoelectrochemical properties.

    PubMed

    Song, Peng; Zhang, Xiaoyan; Sun, Mingxuan; Cui, Xiaoli; Lin, Yuehe

    2012-03-01

    Novel nanocomposite films, based on graphene oxide (GO) and TiO(2) nanotube arrays, were synthesized by assembling GO on the surface of self-organized TiO(2) nanotube arrays through a simple impregnation method. The composite films were characterized with field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and UV-vis diffuse reflectance spectroscopy. The photoelectrochemical properties of the composite nanotube arrays were investigated under visible light illumination. Remarkably enhanced visible light photoelectrochemical response was observed for the GO decorated TiO(2) nanotube composite electrode compared with pristine TiO(2) nanotube arrays. The sensitizing effect of GO on the photoelectrochemical response of the TiO(2) nanotube arrays was demonstrated and about 15 times enhanced maximum photoconversion efficiency was obtained with the presence of GO. An enhanced photocatalytic activity of the TiO(2) nanotube arrays towards the degradation of methyl blue was also demonstrated after modification with GO. The results presented here demonstrate GO to be efficient for the improved utilization of visible light for TiO(2) nanotube arrays. PMID:22297577

  12. Quantum dots sensitized titanium dioxide decorated reduced graphene oxide for visible light excited photoelectrochemical biosensing at a low potential.

    PubMed

    Zeng, Xianxiang; Bao, Jianchun; Han, Min; Tu, Wenwen; Dai, Zhihui

    2014-04-15

    A low potential and competitive photoelectrochemical biosensing platform was developed using quantum dots sensitized titanium dioxide decorated reduced graphene oxide (TiO2-RGO) nanocomposites. The nanocomposites were prepared through electrostatic interaction between mercaptoacetic acid wrapped CdSe quantum dots with negative charge and TiO2-RGO hybrids with positive charge obtained via ultrasonic and acid treatments. Electron microscopes and spectroscopes were used to characterize the functionalized nanocomposites films of CdSe/TiO2-RGO, and the fabrication process of the photoelectrochemical biosensor. Based on the high photovoltaic conversion efficiency of CdSe/TiO2-RGO nanocomposites films, after introducing biological recognition and competitive immunoreaction, a low potential and competitive photoelectrochemical biosensor for carcinoembryonic antigen (CEA) detection was fabricated. The synergic effect of horseradish peroxide and benzo-4-chlorohexadienone decreased the background signal, leading to signal amplification. Under the light irradiation of 430 nm and the applied potential of 0 V, the biosensor detected CEA with a linear range from 0.003 to 100 ng mL(-1) and the detection limit was estimated to be 1.38 pg mL(-1) at a S/N of 3. It was satisfactory for clinical sample detection. The proposed competitive and low potential photoelectrochemical biosensor under irradiation of visible light exhibited good performance, which has a promising prospect in clinical diagnose.

  13. Photoelectrochemical decomposition of pollutants with energy recovery

    SciTech Connect

    Rusling, J.F.; Mbindyo, J.

    1995-12-31

    Catalytic photo-oxidation using titanium dioxide converts most organic pollutants to carbon dioxide, water, and inorganic ions. This process was explored by using laboratory scale photoelectrochemical reactors with nanoparticulate titanium dioxide anodes and cathodes capable of producing hydrogen gas by the reduction of water. Using chlorophenols as test pollutants, quantitative mineralization of milligram quantities of 4-chlorophenol in water to CO{sub 2}, H{sub 2}O and HO was demonstrated using simulated sunlight to illuminate the anode. Hydrogen generation was achieved simultaneously with 65% coulombic efficiency when using acidic catholyte and basic anolyte solutions. Alternatively, the reactor can be used to produce electricity. Results suggest the feasibility of a photoreactor which decomposes pollutants with sunlight, and recovers some of the energy input as hydrogen or electricity.

  14. Biofuel from biomass via photo-electrochemical reactions: An overview

    NASA Astrophysics Data System (ADS)

    Ibrahim, N.; Kamarudin, S. K.; Minggu, L. J.

    2014-08-01

    Biomass is attracting a great deal of attention as a renewable energy resource to reduce carbon dioxide (CO2) emissions. Converting biomass from municipal, agricultural and livestock into biofuel and electrical power has significant environmental and economic advantages. The conversion of biomass into practical energy requires elegant designs and further investigation. Thus, biomass is a promising renewable energy source due to its low production cost and simple manufacturing processes. Biofuel (hydrogen and methanol) from biomass will be possible to be used for transportation with near-zero air pollution, involves efficient uses of land and major contribution to reduce dependence on insecure source of petroleum. Photoelectrochemical (PEC) reactions study has potential pathway for producing fuel from biomass and bio-related compound in the near future. This review highlights recent work related to the PEC conversion of biomass and bio-related compounds into useful biofuels and electricity. This review covers different types of photochemical reaction cells utilizing various types of organic and inorganic waste. It also presents recent developments in photoelectrodes, photocatalysts and electrolytes as well as the production of different types of fuel from PEC cells and highlights current developments and problems in PEC reactions.

  15. Wiring of Photosystem II to Hydrogenase for Photoelectrochemical Water Splitting.

    PubMed

    Mersch, Dirk; Lee, Chong-Yong; Zhang, Jenny Zhenqi; Brinkert, Katharina; Fontecilla-Camps, Juan C; Rutherford, A William; Reisner, Erwin

    2015-07-01

    In natural photosynthesis, light is used for the production of chemical energy carriers to fuel biological activity. The re-engineering of natural photosynthetic pathways can provide inspiration for sustainable fuel production and insights for understanding the process itself. Here, we employ a semiartificial approach to study photobiological water splitting via a pathway unavailable to nature: the direct coupling of the water oxidation enzyme, photosystem II, to the H2 evolving enzyme, hydrogenase. Essential to this approach is the integration of the isolated enzymes into the artificial circuit of a photoelectrochemical cell. We therefore developed a tailor-made hierarchically structured indium-tin oxide electrode that gives rise to the excellent integration of both photosystem II and hydrogenase for performing the anodic and cathodic half-reactions, respectively. When connected together with the aid of an applied bias, the semiartificial cell demonstrated quantitative electron flow from photosystem II to the hydrogenase with the production of H2 and O2 being in the expected two-to-one ratio and a light-to-hydrogen conversion efficiency of 5.4% under low-intensity red-light irradiation. We thereby demonstrate efficient light-driven water splitting using a pathway inaccessible to biology and report on a widely applicable in vitro platform for the controlled coupling of enzymatic redox processes to meaningfully study photocatalytic reactions.

  16. Effect of complexing agent on the photoelectrochemical properties of bath deposited CdS thin films

    NASA Astrophysics Data System (ADS)

    Patil, S. B.; Singh, A. K.

    2010-02-01

    In the present paper photoelectrochemical (PEC) performance of bath deposited CdS thin films based on complexing agents i.e. ammonia and triethanolamine (TEA) has been discussed. Effect of annealing has also been analyzed. The as-deposited and annealed (at 523 K for 1 h in air) films were characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-vis) absorption spectroscopy, SEM, electrochemical impedance spectroscopy (EIS), and PEC properties. XRD studies revealed that the films were nanocrystalline in nature with mixed hexagonal and cubic phases. TEA complex resulted in better crystallinity. Further improvement in the crystallinity of the films was observed after air annealing. The marigold flower-like structure, in addition to flakes morphology, was observed with TEA complex, whereas for ammonia complex only flakes morphology was observed. The UV-vis absorption studies revealed that the optical absorption edge for the films with ammonia and TEA complex was around 475 nm and 500 nm, respectively. Annealing of the films resulted in red shift in the UV-vis absorption. The PEC cell performance of CdS films was found to be strongly affected by crystallinity and morphology of the films resulted due to complexing agent and annealing. The air annealed film deposited using TEA complex showed maximum short circuit current density ( Jsc) and open circuit voltage ( Voc) i.e. 99 μA/cm 2 and 376 mV respectively, under 10 mW/cm 2 of illumination. The films deposited using TEA complex showed good stability under PEC cell conditions.

  17. Dendritic Au/TiO2 nanorod arrays for visible-light driven photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Su, Fengli; Wang, Tuo; Lv, Rui; Zhang, Jijie; Zhang, Peng; Lu, Jianwei; Gong, Jinlong

    2013-09-01

    This paper describes the synthesis of TiO2 branched nanorod arrays (TiO2 BNRs) with plasmonic Au nanoparticles attached on the surface. Such Au/TiO2 BNR composites exhibit high photocatalytic activity in photoelectrochemical (PEC) water splitting. The unique structure of Au/TiO2 BNRs shows enhanced activity with a photocurrent of 0.125 mA cm-2 under visible light (>=420 nm) and 2.32 +/- 0.1 mA cm-2 under AM 1.5 G illumination (100 mW cm-2). The obtained photocurrent is comparable to the highest value ever reported. Furthermore, the Au/TiO2 BNRs achieve the highest efficiency of ~1.27% at a low bias of 0.50 V vs. RHE, indicating elevated charge separation and transportation efficiencies. The high PEC performance is mainly due to the plasmonic effect of Au nanoparticles, which enhances the visible light absorption, together with the large surface area, efficient charge separation and high carrier mobility of the TiO2 BNRs. The carrier density of Au/TiO2 BNRs is nearly 6 times higher than the pristine TiO2 BNRs as calculated by the Mott-Schottky plot. Based on the analysis by UV-Vis spectroscopy, electrochemical impedance spectroscopy, and photoluminescence, a mechanism was proposed to explain the high activity of Au/TiO2 BNRs in PEC water splitting. The capability of synthesizing highly visible light active Au/TiO2 BNR based photocatalysts is useful for solar conversion applications, such as PEC water splitting, dye-sensitized solar cells and photovoltaic devices.This paper describes the synthesis of TiO2 branched nanorod arrays (TiO2 BNRs) with plasmonic Au nanoparticles attached on the surface. Such Au/TiO2 BNR composites exhibit high photocatalytic activity in photoelectrochemical (PEC) water splitting. The unique structure of Au/TiO2 BNRs shows enhanced activity with a photocurrent of 0.125 mA cm-2 under visible light (>=420 nm) and 2.32 +/- 0.1 mA cm-2 under AM 1.5 G illumination (100 mW cm-2). The obtained photocurrent is comparable to the highest value ever

  18. Photocatalysis and photoelectrochemical properties of tungsten trioxide nanostructured films.

    PubMed

    Lai, Chin Wei

    2014-01-01

    Tungsten trioxide (WO₃) possesses a small band gap energy of 2.4-2.8 eV and is responsive to both ultraviolet and visible light irradiation including strong absorption of the solar spectrum and stable physicochemical properties. Thus, controlled growth of one-dimensional (1D) WO₃ nanotubular structures with desired length, diameter, and wall thickness has gained significant interest. In the present study, 1D WO₃ nanotubes were successfully synthesized via electrochemical anodization of tungsten (W) foil in an electrolyte composed of 1 M of sodium sulphate (Na₂SO₄) and ammonium fluoride (NH₄F). The influence of NH₄F content on the formation mechanism of anodic WO₃ nanotubular structure was investigated in detail. An optimization of fluoride ions played a critical role in controlling the chemical dissolution reaction in the interface of W/WO₃. Based on the results obtained, a minimum of 0.7 wt% of NH₄F content was required for completing transformation from W foil to WO₃ nanotubular structure with an average diameter of 85 nm and length of 250 nm within 15 min of anodization time. In this case, high aspect ratio of WO₃ nanotubular structure is preferred because larger active surface area will be provided for better photocatalytic and photoelectrochemical (PEC) reactions.

  19. An electrodeposited inhomogeneous metal-insulator-semiconductor junction for efficient photoelectrochemical water oxidation

    NASA Astrophysics Data System (ADS)

    Hill, James C.; Landers, Alan T.; Switzer, Jay A.

    2015-11-01

    The photoelectrochemical splitting of water into hydrogen and oxygen requires a semiconductor to absorb light and generate electron-hole pairs, and a catalyst to enhance the kinetics of electron transfer between the semiconductor and solution. A crucial question is how this catalyst affects the band bending in the semiconductor, and, therefore, the photovoltage of the cell. We introduce a simple and inexpensive electrodeposition method to produce an efficient n-Si/SiOx/Co/CoOOH photoanode for the photoelectrochemical oxidation of water to oxygen. The photoanode functions as a solid-state, metal-insulator-semiconductor photovoltaic cell with spatially non-uniform barrier heights in series with a low overpotential water-splitting electrochemical cell. The barrier height is a function of the Co coverage; it increases from 0.74 eV for a thick, continuous film to 0.91 eV for a thin, inhomogeneous film that has not reached coalescence. The larger barrier height leads to a 360 mV photovoltage enhancement relative to a solid-state Schottky barrier.

  20. Hierarchically branched Fe2O3@TiO2 nanorod arrays for photoelectrochemical water splitting: facile synthesis and enhanced photoelectrochemical performance.

    PubMed

    Li, Yuangang; Wei, Xiaoliang; Zhu, Bowen; Wang, Hua; Tang, Yuxin; Sum, Tze Chien; Chen, Xiaodong

    2016-06-01

    Highly photoactive and durable photoanode materials are the key to photoelectrochemical water splitting. In this paper, hierarchically branched Fe2O3@TiO2 nanorod arrays (denoted as Fe2O3@TiO2 BNRs) composed of a long Fe2O3 trunk and numerous short TiO2 nanorod branches were fabricated and used as photoanodes for water splitting. Significant improvement of photoelectrochemical water splitting performance was observed based on Fe2O3@TiO2 BNRs. The photocurrent density of Fe2O3@TiO2 BNRs reaches up to 1.3 mA cm(-2) at 1.23 V versus RHE, which is 10 times higher than that of pristine Fe2O3 nanorod arrays under the same conditions. Furthermore, an obvious cathodic shift in the onset potential of photocurrent was observed in the Fe2O3@TiO2 BNRs. More significantly, the Fe2O3@TiO2 BNRs are quite stable even after 3600 s continuous illumination, and the photocurrent density shows almost no decay. Finally, a tentative mechanism was proposed to explain the superior performance of Fe2O3@TiO2 BNRs for PEC water splitting and discussed in detail on the basis of our experimental results.

  1. Photoelectrochemical fabrication of spectroscopic diffraction gratings, phase 2

    NASA Technical Reports Server (NTRS)

    Rauh, R. David; Carrabba, Michael M.; Li, Jianguo; Cartland, Robert F.; Hachey, John P.; Mathew, Sam

    1990-01-01

    This program was directed toward the production of Echelle diffraction gratings by a light-driven, electrochemical etching technique (photoelectrochemical etching). Etching is carried out in single crystal materials, and the differential rate of etching of the different crystallographic planes used to define the groove profiles. Etching of V-groove profiles was first discovered by us during the first phase of this project, which was initially conceived as a general exploration of photoelectrochemical etching techniques for grating fabrication. This highly controllable V-groove etching process was considered to be of high significance for producing low pitch Echelles, and provided the basis for a more extensive Phase 2 investigation.

  2. Cell memory-based therapy.

    PubMed

    Anjamrooz, Seyed Hadi

    2015-11-01

    Current cell therapies, despite all of the progress in this field, still faces major ethical, technical and regulatory hurdles. Because these issues possibly stem from the current, restricted, stereotypical view of cell ultrastructure and function, we must think radically about the nature of the cell. In this regard, the author's theory of the cell memory disc offers 'memory-based therapy', which, with the help of immune system rejuvenation, nervous system control and microparticle-based biodrugs, may have substantial therapeutic potential. In addition to its potential value in the study and prevention of premature cell aging, age-related diseases and cell death, memory therapy may improve the treatment of diseases that are currently limited by genetic disorders, risk of tumour formation and the availability and immunocompatibility of tissue transplants. PMID:26256679

  3. Cell memory-based therapy

    PubMed Central

    Anjamrooz, Seyed Hadi

    2015-01-01

    Current cell therapies, despite all of the progress in this field, still faces major ethical, technical and regulatory hurdles. Because these issues possibly stem from the current, restricted, stereotypical view of cell ultrastructure and function, we must think radically about the nature of the cell. In this regard, the author's theory of the cell memory disc offers ‘memory-based therapy’, which, with the help of immune system rejuvenation, nervous system control and microparticle-based biodrugs, may have substantial therapeutic potential. In addition to its potential value in the study and prevention of premature cell aging, age-related diseases and cell death, memory therapy may improve the treatment of diseases that are currently limited by genetic disorders, risk of tumour formation and the availability and immunocompatibility of tissue transplants. PMID:26256679

  4. Nanostructured TiO2 Films Attached CdSe QDs Toward Enhanced Photoelectrochemical Performance.

    PubMed

    Du, Yingying; Yang, Ping; Liu, Yunshi; Zhao, Jie; He, Haiyan; Miao, Yanping

    2016-06-01

    TiO2 films consisted of small nanoparticles were fabricated via a spinning coating method on fluorine doped in tin oxide (FTO) slide glass. After calcination, the films were subsequently sensitized by CdSe quantum dots (QDs) using mercaptopropionic acid (MPA) as a bifunctional surface modifier. Upon UV light irradiation, CdSe QDs inject electrons into TiO2 nanoparticles, thus resulting in the generation of photocurrent in QD-sensitized solar cell. The results indicate that TiO2 films sensitized by CdSe QDs have achieved 1.5-fold enhancement in photocurrent compared with pure TiO2 films, indicating that CdSe QDs can improve the photocurrent by promoting the separation of photoinduced charge carriers. In addition, the photocurrent enhances as the thickness of TiO2 films increased. Such improved photoelectrochemical performance is ascribed to the basis of improved interfacial charge transport of the TiO2-CdSe composite films. Combining QDs on TiO2 thin films is a promising and effective way to enhance the photoelectrochemical performance, which is important in QD-sensitized solar cell application. PMID:27427714

  5. Graphite-based photovoltaic cells

    DOEpatents

    Lagally, Max; Liu, Feng

    2010-12-28

    The present invention uses lithographically patterned graphite stacks as the basic building elements of an efficient and economical photovoltaic cell. The basic design of the graphite-based photovoltaic cells includes a plurality of spatially separated graphite stacks, each comprising a plurality of vertically stacked, semiconducting graphene sheets (carbon nanoribbons) bridging electrically conductive contacts.

  6. The effect of silver nanoparticles/graphene-coupled TiO2 beads photocatalyst on the photoconversion efficiency of photoelectrochemical hydrogen production.

    PubMed

    Ke, Chun-Ren; Guo, Jyun-Sheng; Su, Yen-Hsun; Ting, Jyh-Ming

    2016-10-28

    In this work, a novel configuration of the photoelectrochemical hydrogen production device is demonstrated. It is based on TiO2 beads as the primary photoanode material with the addition of a heterostructure of silver nanoparticles/graphene. The heterostructure not only caters to a great improvement in light harvesting efficiency (LHE) but also enhances the charge collection efficiency. For LHE, the optimized cell based on TiO2 beads/Ag/graphene shows a 47% gain as compared to the cell having a photoanode of commercial P25 TiO2 powders. For the charge collection efficiency, there is a pronounced improvement of an impressive value of 856%. The reason for the improvement in light absorption is attributed to either the light scattering of TiO2 beads or the surface plasmonic resonance on the Ag nanoparticles/graphene. The photoconversion efficiency (PCE) of the resulting cells is also presented and discussed. The PCE of the TiO2 beads/Ag/graphene cell is approximately 2.5 times than that of pure P25 cell. PMID:27658375

  7. The effect of silver nanoparticles/graphene-coupled TiO2 beads photocatalyst on the photoconversion efficiency of photoelectrochemical hydrogen production.

    PubMed

    Ke, Chun-Ren; Guo, Jyun-Sheng; Su, Yen-Hsun; Ting, Jyh-Ming

    2016-10-28

    In this work, a novel configuration of the photoelectrochemical hydrogen production device is demonstrated. It is based on TiO2 beads as the primary photoanode material with the addition of a heterostructure of silver nanoparticles/graphene. The heterostructure not only caters to a great improvement in light harvesting efficiency (LHE) but also enhances the charge collection efficiency. For LHE, the optimized cell based on TiO2 beads/Ag/graphene shows a 47% gain as compared to the cell having a photoanode of commercial P25 TiO2 powders. For the charge collection efficiency, there is a pronounced improvement of an impressive value of 856%. The reason for the improvement in light absorption is attributed to either the light scattering of TiO2 beads or the surface plasmonic resonance on the Ag nanoparticles/graphene. The photoconversion efficiency (PCE) of the resulting cells is also presented and discussed. The PCE of the TiO2 beads/Ag/graphene cell is approximately 2.5 times than that of pure P25 cell.

  8. The effect of silver nanoparticles/graphene-coupled TiO2 beads photocatalyst on the photoconversion efficiency of photoelectrochemical hydrogen production

    NASA Astrophysics Data System (ADS)

    Ke, Chun-Ren; Guo, Jyun-Sheng; Su, Yen-Hsun; Ting, Jyh-Ming

    2016-10-01

    In this work, a novel configuration of the photoelectrochemical hydrogen production device is demonstrated. It is based on TiO2 beads as the primary photoanode material with the addition of a heterostructure of silver nanoparticles/graphene. The heterostructure not only caters to a great improvement in light harvesting efficiency (LHE) but also enhances the charge collection efficiency. For LHE, the optimized cell based on TiO2 beads/Ag/graphene shows a 47% gain as compared to the cell having a photoanode of commercial P25 TiO2 powders. For the charge collection efficiency, there is a pronounced improvement of an impressive value of 856%. The reason for the improvement in light absorption is attributed to either the light scattering of TiO2 beads or the surface plasmonic resonance on the Ag nanoparticles/graphene. The photoconversion efficiency (PCE) of the resulting cells is also presented and discussed. The PCE of the TiO2 beads/Ag/graphene cell is approximately 2.5 times than that of pure P25 cell.

  9. Formation of single-walled carbon nanotube thin films enriched with semiconducting nanotubes and their application in photoelectrochemical devices.

    PubMed

    Wei, Li; Tezuka, Noriyasu; Umeyama, Tomokazu; Imahori, Hiroshi; Chen, Yuan

    2011-04-01

    Single-walled carbon nanotube (SWCNT) thin films, containing a high-density of semiconducting nanotubes, were obtained by a gel-centrifugation method. The agarose gel concentration and centrifugation force were optimized to achieve high semiconducting and metallic nanotube separation efficiency at 0.1 wt% agarose gel and 18,000g. The thickness of SWCNT films can be precisely controlled from 65 to 260 nm with adjustable transparency. These SWCNT films were applied in photoelectrochemical devices. Photocurrents generated by semiconducting SWCNT enriched films are 15-35% higher than those by unsorted SWCNT films. This is because of reducing exciton recombination channels as a result of the removal of metallic nanotubes. Thinner films generate higher photocurrents because charge carriers have less chances going in metallic nanotubes for recombination, before they can reach electrodes. Developing more scalable and selective methods for high purity semiconducting SWCNTs is important to further improve the photocurrent generation efficiency by using SWCNT-based photoelectrochemical devices.

  10. Anionic ligand assisted synthesis of 3-D hollow TiO2 architecture with enhanced photoelectrochemical performance.

    PubMed

    Shin, Seong Sik; Kim, Dong Wook; Park, Jong Hoon; Kim, Dong Hoe; Kim, Ju Seong; Hong, Kug Sun; Cho, In Sun

    2014-12-30

    Hollow structured materials have shown great advantages for use in photoelectrochemical devices. However, their poor charge transport limits overall device performance. Here, we report a unique 3-D hollow architecture of TiO2 that greatly improves charge transport properties. We found that citric acid (CA) plays crucial roles in the formation of the 3-D hollow architecture. First, CA controls the hydrolysis rate of Ti ions and facilitates surface hydrolysis on templates during hydrothermal synthesis. Second, CA suppresses the growth of the carbon template at the initial reaction stage, resulting in the formation of comparatively small hollow fibers. More importantly, a prolonged hydrothermal reaction with CA enables a hollow sphere to grow into entangled hollow fibers via biomimetic swallowing growth. To demonstrate advantages of the 3-D hollow architecture for photoelectrochemical devices, we evaluated its photoelectrochemical performance, specifically the electrolyte diffusion and electron dynamics, by employing dye-sensitized solar cells as a model device. A systemic analysis reveals that the 3-D hollow architecture greatly improves both the electrolyte diffusion and electron transport compared to those of the nanoparticle and hollow sphere due to the elongated porous hollow morphology as well as the densely interconnected nanoparticles at the wall layer.

  11. The diameter-dependent photoelectrochemical performance of silicon nanowires.

    PubMed

    Zhang, Bing-Chang; Wang, Hui; He, Le; Duan, Chun-Yang; Li, Fan; Ou, Xue-Mei; Sun, Bao-Quan; Zhang, Xiao-Hong

    2016-01-25

    We demonstrate the first systematic study of the diameter-dependent photoelectrochemical performance of single silicon nanowires within a broad size range from 200 to 2000 nm. SiNWs with a diameter of 1415 nm exhibit the highest solar energy conversion efficiency, which can be mainly traced to their diameter-dependent light absorption properties.

  12. Photoelectrochemical solar energy conversion by dye sensitization

    NASA Astrophysics Data System (ADS)

    Grätzel, M.

    1997-04-01

    The lecture describes the salient features of mesoscopic oxide semiconductor film and their electrochemical applications. In particular a molecular photovoltaic device is presented whose overall efficiency for AM 1.5 solar light to electricity at present attains 10-11%. The system is based on the sensitization of nanocrystalline oxide films by molecular charge transfer sensitizers. In analogy to photosynthesis, the new chemical solar cell separates light absorption and charge carrier transport processes. These cells exhibit a remarkable stability making practical applications feasible, the first products being targeted to supply electric power for consumer electronic devices. The mesoscopic oxide semiconductor films offer a number of other attractive research possibilities. Thus, a tandem device based on two superimposed layers with complementary light absorption in the visible range accomplishes the cleavage of water into hydrogen and oxygen with an overall efficiency of 4.5%.

  13. Constructing inverse opal structured hematite photoanodes via electrochemical process and their application to photoelectrochemical water splitting.

    PubMed

    Shi, Xinjian; Zhang, Kan; Shin, Kahee; Moon, Jun Hyuk; Lee, Tae-Woo; Park, Jong Hyeok

    2013-07-28

    In this study, we constructed an inverse opal structured hematite (IOS α-Fe2O3) as the photoanode of a photoelectrochemical (PEC) cell for efficient solar water splitting via a simple electrochemical process. At the same time, a series of affecting factors (template particle size, electrodeposition time and annealing temperature) to construct the IOS α-Fe2O3 photoanode on the photoelectrochemical water splitting were considered. Optimized PEC efficiency was observed for the IOS α-Fe2O3 photoanode annealed at 400 °C using the 250 nm sized-polystyrene (PS) colloid template and 9 minutes of electrodeposition time for the given specific Fe precursor solution. This resulted in the highest photocurrent density compared to other crossed conditions, which significantly achieved 3.1 mA cm(-2) at 0.5 V vs. Ag/AgCl reference electrode. The synthesis of the IOS α-Fe2O3 via an easy-to-control electrochemical process is described for first time that opens a possibility for constructing other oxide semiconductor photoanodes (not only well-known Si, Ti and Zr) with inverse opal structure. PMID:23752489

  14. An investigation of the electrochemical and photoelectrochemical properties of the cuprous oxide/liquid phase boundary

    NASA Astrophysics Data System (ADS)

    Sˇmith, M.; Gotovac, V.; Aljinović, Lj.; Lucˇić-Lavcˇević, M.

    1995-07-01

    In view of the possible application of cuprous oxide in solar energy conversion its physical properties and photoelectrochemical behavior of the phase boundary between the Cu 2O and liquid have been investigated. The composition of galvanostatically deposited films is pure Cu 2O, but its structure is disordered. The conductivity is due to carriers hopping between localized energy states. At room temperature thin Cu 2O films behave like n-type semiconductors. On the basis of the experimental data an energy scheme for the thin oxide semiconductor film is given. From the representative voltammograms in the dark and under illumination it could be concluded that the currents are changed under illumination and that photodegradation takes place. Some unusual phenomena are discussed on the basis of the properties of the thin oxide/electrolyte phase boundary where surface effects are more pronounced than in the bulk material. The conversion efficiency of the Cu 2O photoanode in photoelectrochemical cells is below 1%. An analysis of the causes of this poor performance is given.

  15. CuO-Functionalized Silicon Photoanodes for Photoelectrochemical Water Splitting Devices.

    PubMed

    Shi, Yuanyuan; Gimbert-Suriñach, Carolina; Han, Tingting; Berardi, Serena; Lanza, Mario; Llobet, Antoni

    2016-01-13

    One main difficulty for the technological development of photoelectrochemical (PEC) water splitting (WS) devices is the fabrication of active, stable and cost-effective photoelectrodes that ensure high performance. Here, we report the development of a CuO/Silicon based photoanode, which shows an onset potential for the water oxidation of 0.53 V vs SCE at pH 9, that is, an overpotential of 75 mV, and high stability above 10 h. These values account for a photovoltage of 420 mV due to the absorbed photons by silicon, as proven by comparing with analogous CuO/FTO electrodes that are not photoactive. The photoanodes have been fabricated by sputtering a thin film of Cu(0) on commercially available n-type Si wafers, followed by a photoelectrochemical treatment in basic pH conditions. The resulting CuO/Cu layer acts as (1) protective layer to avoid the corrosion of nSi, (2) p-type hole conducting layer for efficient charge separation and transportation, and (3) electrocatalyst to reduce the overpotential of the water oxidation reaction. The low cost, low toxicity, and good performance of CuO-based coatings can be an attractive solution to functionalize unstable materials for solar energy conversion.

  16. Quantum dot-functionalized porous ZnO nanosheets as a visible light induced photoelectrochemical platform for DNA detection

    NASA Astrophysics Data System (ADS)

    Wang, Wenjing; Hao, Qing; Wang, Wei; Bao, Lei; Lei, Jianping; Wang, Quanbo; Ju, Huangxian

    2014-02-01

    This work reports the synthesis of novel CdTe quantum dot (QD)-functionalized porous ZnO nanosheets via a covalent binding method with (3-aminopropyl)triethoxysilane as a linker. The functional nanosheets showed an excellent visible-light absorbency and much higher photoelectrochemical activity than both CdTe QDs and ZnO nanosheets due to the porous structure and appropriate band alignment between the CdTe QDs and ZnO nanosheets. Using hydrogen peroxide as an electron acceptor the nanosheet-modified electrode showed a sensitive photocurrent response. This speciality led to a novel methodology for the design of hydrogen peroxide-related biosensors by the formation or consumption of hydrogen peroxide. Using biotin-labeled DNA as capture probe, a model biosensor was proposed by immobilizing the probe on a nanosheet-modified electrode to recognize target DNA in the presence of an assistant DNA, which produced a ``Y'' junction structure to trigger a restriction endonuclease-aided target recycling. The target recycling resulted in the release of biotin labeled to the immobilized DNA from the nanosheet-modified electrode, thus decreased the consumption of hydrogen peroxide by horseradish peroxidase-mediated electrochemical reduction after binding the left biotin with horseradish peroxidase-labeled streptavidin, which produced an increasing photoelectrochemical response. The `signal on' strategy for photoelectrochemical detection of DNA showed a low detection limit down to the subfemtomole level and good specificity to single-base mismatched oligonucleotides. The sensitized porous ZnO nanosheets are promising for applications in both photovoltaic devices and photoelectrochemical biosensing.

  17. Quantum dot-functionalized porous ZnO nanosheets as a visible light induced photoelectrochemical platform for DNA detection.

    PubMed

    Wang, Wenjing; Hao, Qing; Wang, Wei; Bao, Lei; Lei, Jianping; Wang, Quanbo; Ju, Huangxian

    2014-03-01

    This work reports the synthesis of novel CdTe quantum dot (QD)-functionalized porous ZnO nanosheets via a covalent binding method with (3-aminopropyl)triethoxysilane as a linker. The functional nanosheets showed an excellent visible-light absorbency and much higher photoelectrochemical activity than both CdTe QDs and ZnO nanosheets due to the porous structure and appropriate band alignment between the CdTe QDs and ZnO nanosheets. Using hydrogen peroxide as an electron acceptor the nanosheet-modified electrode showed a sensitive photocurrent response. This speciality led to a novel methodology for the design of hydrogen peroxide-related biosensors by the formation or consumption of hydrogen peroxide. Using biotin-labeled DNA as capture probe, a model biosensor was proposed by immobilizing the probe on a nanosheet-modified electrode to recognize target DNA in the presence of an assistant DNA, which produced a "Y" junction structure to trigger a restriction endonuclease-aided target recycling. The target recycling resulted in the release of biotin labeled to the immobilized DNA from the nanosheet-modified electrode, thus decreased the consumption of hydrogen peroxide by horseradish peroxidase-mediated electrochemical reduction after binding the left biotin with horseradish peroxidase-labeled streptavidin, which produced an increasing photoelectrochemical response. The 'signal on' strategy for photoelectrochemical detection of DNA showed a low detection limit down to the subfemtomole level and good specificity to single-base mismatched oligonucleotides. The sensitized porous ZnO nanosheets are promising for applications in both photovoltaic devices and photoelectrochemical biosensing.

  18. Quantum dot-functionalized porous ZnO nanosheets as a visible light induced photoelectrochemical platform for DNA detection.

    PubMed

    Wang, Wenjing; Hao, Qing; Wang, Wei; Bao, Lei; Lei, Jianping; Wang, Quanbo; Ju, Huangxian

    2014-03-01

    This work reports the synthesis of novel CdTe quantum dot (QD)-functionalized porous ZnO nanosheets via a covalent binding method with (3-aminopropyl)triethoxysilane as a linker. The functional nanosheets showed an excellent visible-light absorbency and much higher photoelectrochemical activity than both CdTe QDs and ZnO nanosheets due to the porous structure and appropriate band alignment between the CdTe QDs and ZnO nanosheets. Using hydrogen peroxide as an electron acceptor the nanosheet-modified electrode showed a sensitive photocurrent response. This speciality led to a novel methodology for the design of hydrogen peroxide-related biosensors by the formation or consumption of hydrogen peroxide. Using biotin-labeled DNA as capture probe, a model biosensor was proposed by immobilizing the probe on a nanosheet-modified electrode to recognize target DNA in the presence of an assistant DNA, which produced a "Y" junction structure to trigger a restriction endonuclease-aided target recycling. The target recycling resulted in the release of biotin labeled to the immobilized DNA from the nanosheet-modified electrode, thus decreased the consumption of hydrogen peroxide by horseradish peroxidase-mediated electrochemical reduction after binding the left biotin with horseradish peroxidase-labeled streptavidin, which produced an increasing photoelectrochemical response. The 'signal on' strategy for photoelectrochemical detection of DNA showed a low detection limit down to the subfemtomole level and good specificity to single-base mismatched oligonucleotides. The sensitized porous ZnO nanosheets are promising for applications in both photovoltaic devices and photoelectrochemical biosensing. PMID:24457595

  19. Photovoltaic and photoelectrochemical conversion of solar energy.

    PubMed

    Grätzel, Michael

    2007-04-15

    The Sun provides approximately 100,000 terawatts to the Earth which is about 10000 times more than the present rate of the world's present energy consumption. Photovoltaic cells are being increasingly used to tap into this huge resource and will play a key role in future sustainable energy systems. So far, solid-state junction devices, usually made of silicon, crystalline or amorphous, and profiting from the experience and material availability resulting from the semiconductor industry, have dominated photovoltaic solar energy converters. These systems have by now attained a mature state serving a rapidly growing market, expected to rise to 300 GW by 2030. However, the cost of photovoltaic electricity production is still too high to be competitive with nuclear or fossil energy. Thin film photovoltaic cells made of CuInSe or CdTe are being increasingly employed along with amorphous silicon. The recently discovered cells based on mesoscopic inorganic or organic semiconductors commonly referred to as 'bulk' junctions due to their three-dimensional structure are very attractive alternatives which offer the prospect of very low cost fabrication. The prototype of this family of devices is the dye-sensitized solar cell (DSC), which accomplishes the optical absorption and the charge separation processes by the association of a sensitizer as light-absorbing material with a wide band gap semiconductor of mesoporous or nanocrystalline morphology. Research is booming also in the area of third generation photovoltaic cells where multi-junction devices and a recent breakthrough concerning multiple carrier generation in quantum dot absorbers offer promising perspectives. PMID:17272237

  20. Photovoltaic and photoelectrochemical conversion of solar energy.

    PubMed

    Grätzel, Michael

    2007-04-15

    The Sun provides approximately 100,000 terawatts to the Earth which is about 10000 times more than the present rate of the world's present energy consumption. Photovoltaic cells are being increasingly used to tap into this huge resource and will play a key role in future sustainable energy systems. So far, solid-state junction devices, usually made of silicon, crystalline or amorphous, and profiting from the experience and material availability resulting from the semiconductor industry, have dominated photovoltaic solar energy converters. These systems have by now attained a mature state serving a rapidly growing market, expected to rise to 300 GW by 2030. However, the cost of photovoltaic electricity production is still too high to be competitive with nuclear or fossil energy. Thin film photovoltaic cells made of CuInSe or CdTe are being increasingly employed along with amorphous silicon. The recently discovered cells based on mesoscopic inorganic or organic semiconductors commonly referred to as 'bulk' junctions due to their three-dimensional structure are very attractive alternatives which offer the prospect of very low cost fabrication. The prototype of this family of devices is the dye-sensitized solar cell (DSC), which accomplishes the optical absorption and the charge separation processes by the association of a sensitizer as light-absorbing material with a wide band gap semiconductor of mesoporous or nanocrystalline morphology. Research is booming also in the area of third generation photovoltaic cells where multi-junction devices and a recent breakthrough concerning multiple carrier generation in quantum dot absorbers offer promising perspectives.

  1. Efficient water-splitting device based on a bismuth vanadate photoanode and thin-film silicon solar cells.

    PubMed

    Han, Lihao; Abdi, Fatwa F; van de Krol, Roel; Liu, Rui; Huang, Zhuangqun; Lewerenz, Hans-Joachim; Dam, Bernard; Zeman, Miro; Smets, Arno H M

    2014-10-01

    A hybrid photovoltaic/photoelectrochemical (PV/PEC) water-splitting device with a benchmark solar-to-hydrogen conversion efficiency of 5.2% under simulated air mass (AM) 1.5 illumination is reported. This cell consists of a gradient-doped tungsten-bismuth vanadate (W:BiVO4 ) photoanode and a thin-film silicon solar cell. The improvement with respect to an earlier cell that also used gradient-doped W:BiVO4 has been achieved by simultaneously introducing a textured substrate to enhance light trapping in the BiVO4 photoanode and further optimization of the W gradient doping profile in the photoanode. Various PV cells have been studied in combination with this BiVO4 photoanode, such as an amorphous silicon (a-Si:H) single junction, an a-Si:H/a-Si:H double junction, and an a-Si:H/nanocrystalline silicon (nc-Si:H) micromorph junction. The highest conversion efficiency, which is also the record efficiency for metal oxide based water-splitting devices, is reached for a tandem system consisting of the optimized W:BiVO4 photoanode and the micromorph (a-Si:H/nc-Si:H) cell. This record efficiency is attributed to the increased performance of the BiVO4 photoanode, which is the limiting factor in this hybrid PEC/PV device, as well as better spectral matching between BiVO4 and the nc-Si:H cell.

  2. A new approach to light up the application of semiconductor nanomaterials for photoelectrochemical biosensors: using self-operating photocathode as a highly selective enzyme sensor.

    PubMed

    Wang, Guang-Li; Liu, Kang-Li; Dong, Yu-Ming; Wu, Xiu-Ming; Li, Zai-Jun; Zhang, Chi

    2014-12-15

    Due to the intrinsic hole oxidation reaction occurred on the photoanode surface, currently developed photoelectrochemical biosensors suffer from the interference from coexisting reductive species (acting as electron donor) and a novel design strategy of photoelectrode for photoelectrochemical detection is urgently required. In this paper, a self-operating photocathode based on CdS quantum dots sensitized three-dimensional (3D) nanoporous NiO was designed and created, which showed highly selective and reversible response to dissolved oxygen (acting as electron acceptor) in the electrolyte solution. Using glucose oxidase (GOD) as a biocatalyst, a novel photoelectrochemical sensor for glucose was developed. The commonly encountered interferents such as H2O2, ascorbic acid (AA), cysteine (Cys), dopamine (DA), etc., almost had no effect for the cathodic photocurrent of the 3D NiO/CdS electrode, though these substances were proved to greatly influence the photocurrent of photoanodes, which indicated greatly improved selectivity of the method. The method was applied to detect glucose in real samples including serum and glucose injections with satisfactory results. This study could provide a new train of thought on designing of self-operating photocathode in photoelectrochemical sensing, promoting the application of semiconductor nanomaterials in photoelectrochemistry. PMID:24984285

  3. Size-selected TiO₂ nanocluster catalysts for efficient photoelectrochemical water splitting.

    PubMed

    Srivastava, Saurabh; Thomas, Joseph Palathinkal; Rahman, Md Anisur; Abd-Ellah, Marwa; Mohapatra, Mamata; Pradhan, Debabrata; Heinig, Nina F; Leung, Kam Tong

    2014-11-25

    Nanoclusters (NCs) are of great interest because they provide the link between the distinct behavior of atoms and nanoparticles and that of bulk materials. Here, we report precisely controlled deposition of size-selected TiO2 NCs produced by gas-phase aggregation in a special magnetron sputtering system. Carefully optimized aggregation length and Ar gas flow are used to control the size distribution, while a quadrupole mass filter provides precise in situ size selection (from 2 to 15 nm). Transmission electron microscopy studies reveal that NCs larger than a critical size (∼8 nm) have a crystalline core with an amorphous shell, while those smaller than the critical size are all amorphous. The TiO2 NCs so produced exhibit remarkable photoelectrochemical water splitting performance in spite of a small amount of material loading. NCs of three different sizes (4, 6, and 8 nm) deposited on H-terminated Si(100) substrates are tested for the photoelectrochemical catalytic performance, and significant enhancement in photocurrent density (0.8 mA/cm(2)) with decreasing NC size is observed with a low saturation voltage of -0.22 V vs Ag/AgCl (0.78 V vs RHE). The enhanced photoconductivity could be attributed to the increase in the specific surface area and increase in the number of active (defect) sites in the amorphous NCs. The unique advantages of the present technique will be further exploited to develop applications based on tunable, size-selected NCs.

  4. Photoelectrochemical oxidation of ibuprofen via Cu2O-doped TiO2 nanotube arrays.

    PubMed

    Sun, Qiannan; Peng, Yen-Ping; Chen, Hanlin; Chang, Ken-Lin; Qiu, Yang-Neng; Lai, Shiau-Wu

    2016-12-01

    A p-n junction based Cu2O-doped TiO2 nanotube arrays (Cu2O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu2O-TNAs were dominated by the anatase phase and responded significantly to visible light. XPS analyses indicated that with an amount of 24.79% Cu doping into the structure, the band gap of Cu2O-TNAs was greatly reduced. SEM images revealed that the supported TiO2 nanotubes had diameters of approximately 80nm and lengths of about 2.63μm. Upon doping with Cu2O, the TiO2 nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu2O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu2O significantly improved electron mobility by reducing the rate of recombination of electron-hole pairs. The EIS and Bode plot revealed that the estimated electron lifetimes, τel, of TNAs and Cu2O/TNAs were 6.91 and 26.26ms, respectively. The efficiencies of degradation of Ibuprofen by photoelectrochemical, photocatalytic (PC), electrochemical (EC) and photolytic (P) methods were measured. PMID:27021261

  5. Plasmonic layer enhanced photoelectrochemical response of Fe2O3 photoanodes

    NASA Astrophysics Data System (ADS)

    Verma, Anuradha; Srivastav, Anupam; Banerjee, Anamika; Sharma, Dipika; Sharma, Shailja; Singh, Udai Bhan; Satsangi, Vibha Rani; Shrivastav, Rohit; Avasthi, Devesh Kumar; Dass, Sahab

    2016-05-01

    Present experimental study focuses on the influence of plasmonic layer in Zr-doped Fe2O3 (Z-F) thin film based photoanodes deposited in different configurations for photo splitting of water. The Au nanoparticles (plasmonic layer) as bottom layer and surface (top) layer are incorporated in the spray pyrolytically deposited Z-F thin layer. In addition to this, fabrication of Z-F sandwiched between two plasmonic Au layers (Au/Z-F/Au) as well as plasmonic Au layer sandwiched between two Z-F layers (Z-F/Au/Z-F) are also undertaken. All configurations using plasmonic layer show enhanced photoresponse in comparison to the pristine Z-F samples. The Z-F sandwiched between two plasmonic layers shows the most significant increase in photocurrent density at 0.8 V/SCE (Saturated Calomel Electrode) and also improved optical absorption due to the presence of two palsmonic layers which promote charge transfer and inhibit charge recombination. The obtained results are supported by characterization techniques viz. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX), UV-Visible absorption spectroscopy, Photoelectrochemical properties, Mott-Schottky analysis and efficiency measurements of photoelectrochemical (PEC) sytstem.

  6. ZnO-Au-SnO2 Z-scheme photoanodes for remarkable photoelectrochemical water splitting.

    PubMed

    Li, Jing-Mei; Cheng, Hao-Yun; Chiu, Yi-Hsuan; Hsu, Yung-Jung

    2016-08-25

    For the first time a ZnO nanorod-based Z-scheme heterostructure system was proposed and realized for efficient photoelectrochemical water splitting. The samples were prepared by depositing a thin layer of SnO2 on the Au surface of Au particle-decorated ZnO nanorods. For ZnO-Au-SnO2 nanorods, the embedded Au can mediate interfacial charge transfer by promoting electron transfer from the conduction band of SnO2 to the valence band of ZnO. This vectorial charge transfer resulted in the situation that the photoexcited electrons accumulated at ZnO while the photogenerated holes concentrated at SnO2, giving ZnO-Au-SnO2 substantially high redox powers. Time-resolved photoluminescence spectra suggested that the interfacial charge transfer across the ZnO/Au/SnO2 interface was significantly improved as a result of the Z-scheme charge transfer mechanism. With the substantially high redox powers and significantly improved interfacial charge transfer, ZnO-Au-SnO2 nanorods performed much better as a photoanode in photoelectrochemical water splitting than pristine ZnO, plasmonic Au-decorated ZnO and type-II SnO2-coated ZnO nanorods did. The present study has provided a viable approach to exploit Z-scheme photoanodes in the design of efficient artificial photosynthesis systems for solar energy conversion. PMID:27527337

  7. Interplay of light transmission and catalytic exchange current in photoelectrochemical systems

    SciTech Connect

    Fountaine, Katherine T.; Lewerenz, Hans J.; Atwater, Harry A.

    2014-10-27

    We develop an analytic current-voltage expression for a variable junction photoelectrochemical (PEC) cell and use it to investigate and illustrate the influence of the optical and electrical properties of catalysts on the optoelectronic performance of PEC devices. Specifically, the model enables a simple, yet accurate accounting of nanostructured catalyst optical and electrical properties through incorporation of an optical transmission factor and active catalytic area factor. We demonstrate the utility of this model via the output power characteristics of an exemplary dual tandem solar cell with indium gallium phosphide and indium gallium arsenide absorbers with varying rhodium catalyst nanoparticle loading. The approach highlights the importance of considering interactions between independently optimized components for optimal PEC device design.

  8. Solid state photovoltaic cells based on localized surface plasmon-induced charge separation

    NASA Astrophysics Data System (ADS)

    Takahashi, Yukina; Tatsuma, Tetsu

    2011-10-01

    Charge separation induced by localized surface plasmon resonance (LSPR) of gold and silver nanoparticles (AuNPs and AgNPs) are applied to various devices and photoelectrochemical functionalities. Here, we develop all solid state In/TiO2/MNPs/ITO photovoltaic cells (MNP = AuNP or AgNP) by using two-dimensional MNP ensembles. Their quantum efficiencies are higher than those of previously reported solid state cells with hole-transport materials (HTMs) (ITO/TiO2/AuNPs/HTM/Au). The photoresponses from cells without HTMs suggest that the photovoltage generates at the TiO2-MNP interface.

  9. Stable Hematite Nanosheet Photoanodes for Enhanced Photoelectrochemical Water Splitting.

    PubMed

    Peerakiatkhajohn, Piangjai; Yun, Jung-Ho; Chen, Hongjun; Lyu, Miaoqiang; Butburee, Teera; Wang, Lianzhou

    2016-08-01

    A vertically grown hematite nanosheet film modified with Ag nanoparticles (NPs) and Co-Pi cocatalyst exhibits a remarkably high photocurrent density of 4.68 mA cm(-2) at 1.23 V versus RHE. The Ag NPs leads to significantly improved light harvesting and better charge transfer, while the Co-Pi facilitates a highly stable oxygen evolution process. This photoelectrode design provides more efficient photoelectrochemical systems for solar-energy conversion. PMID:27167876

  10. Rational design of semiconductors for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Wei, Su-Huai

    2013-12-01

    Using first-principles method as a tool, we discuss the general strategies for the rational design of semiconductors to simultaneously meet all of requirements for high-efficiency, solar-driven photoelectrochemical (PEC) water-splitting devices. Our studies demonstrate that theoretical calculations, which provided deep understanding of the underlying physics behind these PEC materials, can greatly accelerate scientific discovery of new PEC materials in this exciting field.

  11. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures

    DOEpatents

    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.

    2016-03-01

    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  12. Quantum-dot-sensitized TiO2 inverse opals for photoelectrochemical hydrogen generation.

    PubMed

    Cheng, Chuanwei; Karuturi, Siva Krishna; Liu, Lijun; Liu, Jinping; Li, Hongxing; Su, Liap Tat; Tok, Alfred Iing Yoong; Fan, Hong Jin

    2012-01-01

    A new nanoarchitecture photoelectrode design comprising CdS quantum-dot-sensitized, optically and electrically active TiO(2) inverse opals is developed for photoelectrochemical water splitting. The photoelectrochemical performance shows high photocurrent density (4.84 mA cm(-2) at 0 V vs. Ag/AgCl) under simulated solar-light illumination. PMID:22009604

  13. Quantum-dot-sensitized TiO2 inverse opals for photoelectrochemical hydrogen generation.

    PubMed

    Cheng, Chuanwei; Karuturi, Siva Krishna; Liu, Lijun; Liu, Jinping; Li, Hongxing; Su, Liap Tat; Tok, Alfred Iing Yoong; Fan, Hong Jin

    2012-01-01

    A new nanoarchitecture photoelectrode design comprising CdS quantum-dot-sensitized, optically and electrically active TiO(2) inverse opals is developed for photoelectrochemical water splitting. The photoelectrochemical performance shows high photocurrent density (4.84 mA cm(-2) at 0 V vs. Ag/AgCl) under simulated solar-light illumination.

  14. CoSe₂ and NiSe₂ Nanocrystals as Superior Bifunctional Catalysts for Electrochemical and Photoelectrochemical Water Splitting.

    PubMed

    Kwak, In Hye; Im, Hyung Soon; Jang, Dong Myung; Kim, Young Woon; Park, Kidong; Lim, Young Rok; Cha, Eun Hee; Park, Jeunghee

    2016-03-01

    Catalysts for oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) are central to key renewable energy technologies, including fuel cells and water splitting. Despite tremendous effort, the development of low-cost electrode catalysts with high activity remains a great challenge. In this study, we report the synthesis of CoSe2 and NiSe2 nanocrystals (NCs) as excellent bifunctional catalysts for simultaneous generation of H2 and O2 in water-splitting reactions. NiSe2 NCs exhibit superior electrocatalytic efficiency in OER, with a Tafel slope (b) of 38 mV dec(-1) (in 1 M KOH), and HER, with b = 44 mV dec(-1) (in 0.5 M H2SO4). In comparison, CoSe2 NCs are less efficient for OER (b = 50 mV dec(-1)), but more efficient for HER (b = 40 mV dec(-1)). It was found that CoSe2 NCs contained more metallic metal ions than NiSe2, which could be responsible for their improved performance in HER. Robust evidence for surface oxidation suggests that the surface oxide layers are the actual active sites for OER, and that CoSe2 (or NiSe2) under the surface act as good conductive layers. The higher catalytic activity of NiSe2 is attributed to their oxide layers being more active than those of CoSe2. Furthermore, we fabricated a Si-based photoanode by depositing NiSe2 NCs onto an n-type Si nanowire array, which showed efficient photoelectrochemical water oxidation with a low onset potential (0.7 V versus reversible hydrogen electrode) and high durability. The remarkable catalytic activity, low cost, and scalability of NiSe2 make it a promising candidate for practical water-splitting solar cells. PMID:26848805

  15. CoSe₂ and NiSe₂ Nanocrystals as Superior Bifunctional Catalysts for Electrochemical and Photoelectrochemical Water Splitting.

    PubMed

    Kwak, In Hye; Im, Hyung Soon; Jang, Dong Myung; Kim, Young Woon; Park, Kidong; Lim, Young Rok; Cha, Eun Hee; Park, Jeunghee

    2016-03-01

    Catalysts for oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) are central to key renewable energy technologies, including fuel cells and water splitting. Despite tremendous effort, the development of low-cost electrode catalysts with high activity remains a great challenge. In this study, we report the synthesis of CoSe2 and NiSe2 nanocrystals (NCs) as excellent bifunctional catalysts for simultaneous generation of H2 and O2 in water-splitting reactions. NiSe2 NCs exhibit superior electrocatalytic efficiency in OER, with a Tafel slope (b) of 38 mV dec(-1) (in 1 M KOH), and HER, with b = 44 mV dec(-1) (in 0.5 M H2SO4). In comparison, CoSe2 NCs are less efficient for OER (b = 50 mV dec(-1)), but more efficient for HER (b = 40 mV dec(-1)). It was found that CoSe2 NCs contained more metallic metal ions than NiSe2, which could be responsible for their improved performance in HER. Robust evidence for surface oxidation suggests that the surface oxide layers are the actual active sites for OER, and that CoSe2 (or NiSe2) under the surface act as good conductive layers. The higher catalytic activity of NiSe2 is attributed to their oxide layers being more active than those of CoSe2. Furthermore, we fabricated a Si-based photoanode by depositing NiSe2 NCs onto an n-type Si nanowire array, which showed efficient photoelectrochemical water oxidation with a low onset potential (0.7 V versus reversible hydrogen electrode) and high durability. The remarkable catalytic activity, low cost, and scalability of NiSe2 make it a promising candidate for practical water-splitting solar cells.

  16. Silicon Microwire Arrays for Photoelectrochemical and Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Warren, Emily Lowell

    Si microwire (Si MW) arrays grown by the vapor-liquid-solid (VLS) process are promising materials for next-generation solar energy devices. High-aspect-ratio semiconductor structures have attracted recent interest as solar absorber materials because their radial geometry decouples the direction of light absorption and carrier collection, enabling the use of materials with shorter minority-carrier diffusion lengths than would be acceptable in a planar geometry. The VLS growth process is a low-cost deposition technique, which can be used to fabricate flexible, high-performance semiconductor materials. Si MW arrays have been investigated as an inexpensive alternative to wafer-based solar photovoltaics for low- cost electricity generation. Another potential application is to use these vertically oriented wire arrays as photocathodes of a solar fuel conversion devices, where instead of producing electricity, sunlight is used to directly drive a fuel-forming reaction (e.g., splitting water to form O 2 and H2). The high aspect ratio of the Si MW arrays provides a large surface area for the integration of fuel-forming catalysts, allowing for the development of a low-cost, scalable, energy storage technology. This thesis discusses the fabrication and photoelectrochemical characterization of Si MWs grown by the VLS process, focusing on the use of these wire arrays as hydrogen- evolving photocathodes for solar water-splitting. To optimize such a device it is important to balance all of the factors that will affect performance: light absorption, band energetics, attainable open circuit voltage, and catalysis. First, we characterize the electrical performance of the wire arrays using regenerative photoelectrochemistry to understand the material quality and band energetics at the Si/water interface. We demonstrate the fabrication of H2-evolving photocathodes using p-n junction Si MW arrays and earth-abundant Ni-Mo alloy hydrogen evolution catalysts. We then investigate modifying

  17. Carbon-based Fuel Cell

    SciTech Connect

    Steven S. C. Chuang

    2005-08-31

    The direct use of coal in the solid oxide fuel cell to generate electricity is an innovative concept for power generation. The C-fuel cell (carbon-based fuel cell) could offer significant advantages: (1) minimization of NOx emissions due to its operating temperature range of 700-1000 C, (2) high overall efficiency because of the direct conversion of coal to CO{sub 2}, and (3) the production of a nearly pure CO{sub 2} exhaust stream for the direct CO{sub 2} sequestration. The objective of this project is to determine the technical feasibility of using a highly active anode catalyst in a solid oxide fuel for the direct electrochemical oxidation of coal to produce electricity. Results of this study showed that the electric power generation from Ohio No 5 coal (Lower Kittanning) Seam, Mahoning County, is higher than those of coal gas and pure methane on a solid oxide fuel cell assembly with a promoted metal anode catalyst at 950 C. Further study is needed to test the long term activity, selectivity, and stability of anode catalysts.

  18. Photochemical solar cells based on dye-sensitization of nanocrystalline TiO{sub 2}

    SciTech Connect

    Deb, S.K.; Ellingson, R.; Ferrere, S.; Frank, A.J.; Gregg, B.A.; Nozik, A.J.; Park, N.; Schlichthoerl, G.

    1998-09-01

    A photoelectrochemical solar cell that is based on the dye-sensitization of thin nanocrystalline films of TiO{sub 2} (anatase) nanoparticles in contact with a non-aqueous liquid electrolyte is described. The cell, fabricated at NREL, shows a conversion efficiency of {approximately} 9.2% at AM1.5, which approaches the best reported value of 10--11% by Graetzel at EPFL in Lausanne, Switzerland. The femtosecond (fs) pump-probe spectroscopy has been used to time resolve the injection of electrons into the conduction band of nanocrystalline TiO{sub 2} films under ambient conditions following photoexcitation of the adsorbed Ru(II)-complex dye. The measurement indicates an instrument-limited {minus}50 fs upper limit on the electron injection time. The authors also report the sensitization of nanocrystalline TiO{sub 2} by a novel iron-based dye, CIS-[Fe{sup II}(2,2{prime}-bipyridine-4,4,{prime}-dicarboxylic acid){sub 2}(CN){sub 2}], a chromophore with an extremely short-lived, nonemissive excited state. The dye also exhibits a unique band selective sensitization through one of its two absorption bands. The operational principle of the device has been studied through the measurement of electric field distribution within the device structure and studies on the pH dependence of dye-redox potential. The incorporation of WO{sub 3}-based electrochromic layer into this device has led to a novel photoelectrochromic device structure for smart window application.

  19. High-performance photoelectrochemical-type self-powered UV photodetector using epitaxial TiO₂/SnO₂ branched heterojunction nanostructure.

    PubMed

    Li, Xiaodong; Gao, Caitian; Duan, Huigao; Lu, Bingan; Wang, Youqing; Chen, Lulu; Zhang, Zhenxing; Pan, Xiaojun; Xie, Erqing

    2013-06-10

    TiO₂/SnO₂ branched heterojunction nanostructure with TiO₂ branches on electrospun SnO2 nanofiber (B-SnO₂ NF) networks serves as a model architecture for efficient self-powered UV photodetector based on a photoelectrochemical cell (PECC). The nanostructure simultaneously offers a low degree of charge recombination and a direct pathway for electron transport. Without correcting 64.5% loss of incident photons through light absorption and scattering by the F-doped tin oxide (FTO) glass, the incident power conversion efficiency reaches 14.7% at 330 nm, more than twice as large as the nanocrystalline TiO₂ (TiO₂ NC, 6.4%)-film based PECC. By connecting a PECC to an ammeter, the intensity of UV light is quantified using the output short-circuit photocurrent density (J(sc)) without a power source. Under UV irradiation, the self-powered UV photodetector exhibits a high responsivity of 0.6 A/W, a high on/off ratio of 4550, a rise time of 0.03 s and a decay time of 0.01 s for J(sc) signal. The excellent performance of the B-SnO₂ NF-based PECC type self-powered photodetector will enable significant advancements for next-generation photodetection and photosensing applications.

  20. n-CuInSe2 based photoelectrochemical cells: Improved, stable performance in aqueous polyiodide through rational surface and solution modifications

    NASA Astrophysics Data System (ADS)

    Cahen, David; Chen, Yih-Wen

    1984-10-01

    Surface optimization of n-CuInSe2 crystals by chemical etching in Br2/MeOH and subsequent thermal oxidation results in >10% efficient photanodes in neutral aqueous polyiodide. The etchant removes a near-stoichiometric surface layer and thermal oxidation leads to In-O bond formation. We find from (photo) electrochemical studies in acetonitrile and in the iodide electrolyte that, upon semiconductor decomposition, Cu ions are released into the solution, consistent with solid state chemical studies that show the existence of the chalcopyrite phase also towards Cu-poor compositions. Addition of Cu ions, as also reported by S. Menezes, H. J. Lewerenz, and K. J. Bachmann [Nature (London) 305, 615 (1983)] or Cu and In ions to the iodide solution drastically decreases photoanode decomposition. Covering the electrode with an extra film of oxidized indium results in true stabilization, at up to 11.7% conversion efficiency under 120-mW/cm2 tungsten-halogen illumination. Because, in the presence of Cu ions and under illumination, iodide solutions are not completely stable towards oxidation by O2, especially if the solution is acidic, an air-free electrolyte needs to be used.

  1. Facile solution deposition of Cu2ZnSnS4 (CZTS) nano-worm films on FTO substrates and its photoelectrochemical property

    NASA Astrophysics Data System (ADS)

    Huang, Yaohan; Li, Guangli; Fan, Qingfei; Zhang, Meili; Lan, Qi; Fan, Ximei; Zhou, Zuowan; Zhang, Chaoliang

    2016-02-01

    In this work, Cu2ZnSnS4 (CZTS) nanoworm films have been directly deposited on fluorine-doped tin oxide (FTO) conductive glass substrates by a solvothermal method using polyethylene glycol 400 (PEG-400) as the solvent and structure-directing agent. The as-obtained CZTS thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectrum (XPS), UV-vis spectra and photoelectrochemical measurement. The synthetic conditions, such as reaction temperature, reaction time, solvents, were investigated to know the formation of CZTS thin films. The results showed that PEG-400 plays a key role in the formation of the nanoworms by affecting the crystal growth process. The p-type CZTS nanoworm film with the band gap of 1.62 eV was synthesized at 180 °C for 22 h and the photovoltaic performance was studied by forming a photoelectrochemical cell.

  2. Wireless InGaN-Si/Pt device for photo-electrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Sekimoto, Takeyuki; Hashiba, Hiroshi; Shinagawa, Shuichi; Uetake, Yusuke; Deguchi, Masahiro; Yotsuhashi, Satoshi; Ohkawa, Kazuhiro

    2016-08-01

    We demonstrate a wireless device comprising a gallium nitride (GaN)-silicon-based photo-electrode, and a platinum cathode. Compared with conventional two-electrode photo-electrochemical systems, this wireless monolithic device showed potential for a wider range of applications, and reduced the resistance losses resulting from the wiring and aqueous solution. The efficiency was improved when the electrolyte was changed from KHCO3 to NaOH because water oxidation capability of the surface of the GaN was enhanced. A wider solar spectrum wavelength range was exploited by adopting InGaN as a photo-absorption layer; the improved efficiency for hydrogen generation was 0.90%.

  3. Wireless InGaN–Si/Pt device for photo-electrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Sekimoto, Takeyuki; Hashiba, Hiroshi; Shinagawa, Shuichi; Uetake, Yusuke; Deguchi, Masahiro; Yotsuhashi, Satoshi; Ohkawa, Kazuhiro

    2016-08-01

    We demonstrate a wireless device comprising a gallium nitride (GaN)–silicon-based photo-electrode, and a platinum cathode. Compared with conventional two-electrode photo-electrochemical systems, this wireless monolithic device showed potential for a wider range of applications, and reduced the resistance losses resulting from the wiring and aqueous solution. The efficiency was improved when the electrolyte was changed from KHCO3 to NaOH because water oxidation capability of the surface of the GaN was enhanced. A wider solar spectrum wavelength range was exploited by adopting InGaN as a photo-absorption layer; the improved efficiency for hydrogen generation was 0.90%.

  4. Electrochemically reduced graphene oxide on silicon nanowire arrays for enhanced photoelectrochemical hydrogen evolution.

    PubMed

    Meng, Huan; Fan, Ke; Low, Jingxiang; Yu, Jiaguo

    2016-09-21

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen by sunlight is a promising approach to solve energy and environmental problems. In this work, silicon nanowire arrays (SiNWs) photocathodes decorated with reduced graphene oxide (rGO) for PEC water splitting were successfully prepared by a flexible and scalable electrochemical reduction method. The SiNWs photocathode with the optimized rGO decoration (SiNWs/rGO20) shows an enhanced activity with a much higher photocurrent density and significantly positive shift of onset potential compared to the bare SiNWs arrays for the hydrogen evolution reaction (HER). The enhanced PEC activity is ascribed to the high electrical conductivity of rGO and improved separation of the photogenerated charge carriers. This work not only demonstrates a facile, rapid and tunable electrochemical reduction method to produce rGO, but also exhibits an efficient protocol to enhance the PEC water splitting of silicon-based materials. PMID:27461187

  5. Electrochemically reduced graphene oxide on silicon nanowire arrays for enhanced photoelectrochemical hydrogen evolution.

    PubMed

    Meng, Huan; Fan, Ke; Low, Jingxiang; Yu, Jiaguo

    2016-09-21

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen by sunlight is a promising approach to solve energy and environmental problems. In this work, silicon nanowire arrays (SiNWs) photocathodes decorated with reduced graphene oxide (rGO) for PEC water splitting were successfully prepared by a flexible and scalable electrochemical reduction method. The SiNWs photocathode with the optimized rGO decoration (SiNWs/rGO20) shows an enhanced activity with a much higher photocurrent density and significantly positive shift of onset potential compared to the bare SiNWs arrays for the hydrogen evolution reaction (HER). The enhanced PEC activity is ascribed to the high electrical conductivity of rGO and improved separation of the photogenerated charge carriers. This work not only demonstrates a facile, rapid and tunable electrochemical reduction method to produce rGO, but also exhibits an efficient protocol to enhance the PEC water splitting of silicon-based materials.

  6. In Situ Synthesis of Metal Sulfide Nanoparticles Based on 2D Metal-Organic Framework Nanosheets.

    PubMed

    Lu, Qipeng; Zhao, Meiting; Chen, Junze; Chen, Bo; Tan, Chaoliang; Zhang, Xiao; Huang, Ying; Yang, Jian; Cao, Feifei; Yu, Yifu; Ping, Jianfeng; Zhang, Zhicheng; Wu, Xue-Jun; Zhang, Hua

    2016-09-01

    A facile in situ synthetic method is developed to synthesize metal sulfide nanoparticles based on 2D M-TCPP (M = Cu, Cd, or Co, TCPP = tetrakis(4-carboxyphenyl)porphyrin)) metal-organic framework nanosheets. The obtained CuS/Cu-TCPP composite nanosheet is used as the active material in photoelectrochemical cells, showing notably increased photocurrent due to the improved exciton separation and charge carrier transport.

  7. Preparation and surface modification of hierarchical nanosheets-based ZnO microstructures for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Meng, Yongming; Lin, Yu; Lin, Yibing; Yang, Jiyuan

    2014-02-01

    This paper reports a simple one-step hydrothermal route for the preparation of hierarchical nanosheets-based ZnO microstructures and their application to dye-sensitized solar cells. The morphologies of the products were controlled by the dosage of the reactants. Their physical characteristics were detected by X-ray diffraction, a field-emission scanning electron microscope and a surface analyzer. It is proved that the sample of ZnO microspheres with larger surface area and stronger light-trapping capacity since the superiority of their entirely spherical structures exhibits better photoelectrochemical properties than the mixtures of ZnO microspheres and ZnO microflowers. A dye-sensitized solar cell assembled by the ZnO microspheres as photoanode shows an energy conversion efficiency of 2.94% after surface modification by tetrabutyl titanate solution at 90 °C. This result is over 1.6 times higher than the non-modified cell fabricated by the ZnO microspheres on the basis of the external improvement and the stability enhancement for the dye-sensitized ZnO photoanode.

  8. Unbiased photoelectrochemical water splitting in Z-scheme device using W/Mo-doped BiVO4 and Zn(x)Cd(1-x)Se.

    PubMed

    Park, Hyun S; Lee, Heung Chan; Leonard, Kevin C; Liu, Guanjie; Bard, Allen J

    2013-07-22

    Photoelectrochemical water splitting to generate H2 and O2 using only photon energy (with no added electrical energy) has been demonstrated with dual n-type-semiconductor (or Z-scheme) systems. Here we investigated two different Z-scheme systems; one is comprised of two cells with the same metal-oxide semiconductor (W- and Mo-doped bismuth vanadate), that is, Pt-W/Mo-BiVO4, and the other is comprised of the metal oxide and a chalcogenide semiconductor, that is, Pt-W/Mo-BiVO4 and Zn(0.2)Cd(0.8)Se. The redox couples utilized in these Z-scheme configurations were I(-)/IO3(-) or S(2-)/S(n)(2-), respectively. An electrochemical analysis of the system in terms of cell components is shown to illustrate the behavior of the complete photoelectrochemical Z-scheme water-splitting system. H2 gas from the unbiased photolysis of water was detected using gas chromatography-mass spectroscopy and using a membrane-electrode assembly. The electrode configuration to achieve the maximum conversion efficiency from solar energy to chemical energy with the given materials and the Z-scheme is discussed. Here, the possibilities and challenges of Z-scheme unbiased photoelectrochemical water-splitting devices and the materials to achieve practical solar-fuel generation are discussed.

  9. All-nanoparticle self-assembly ZnO/TiO₂ heterojunction thin films with remarkably enhanced photoelectrochemical activity.

    PubMed

    Yuan, Sujun; Mu, Jiuke; Mao, Ruiyi; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

    2014-04-23

    The multilaminated ZnO/TiO2 heterojunction films were successfully deposited on conductive substrates including fluorine-doped tin oxide (FTO) glass and flexible indium tin oxide coated poly(ethylene terephthalate) via the layer-by-layer (LBL) self assembly method from the oxide colloids without using any polyelectrolytes. The positively charged ZnO nanoparticles and the negatively charged TiO2 nanoparticles were directly used as the components in the consecutive deposition process to prepare the heterojunction thin films by varying the thicknesses. Moreover, the crystal growth of both oxides could be efficiently inhibited by the good connection between ZnO and TiO2 nanoparticles even after calcination at 500 °C, especially for ZnO which was able to keep the crystallite size under 25 nm. The as-prepared films were used as the working electrodes in the three-electrode photoelectrochemical cells. Because the well-contacted nanoscale heterojunctions were formed during the LBL self-assembling process, the ZnO/TiO2 all-nanoparticle films deposited on both substrates showed remarkably enhanced photoelectrochemical properties compared to that of the well-established TiO2 LBL thin films with similar thicknesses. The photocurrent response collected from the ZnO/TiO2 electrode on the FTO glass substrate was about five times higher than that collected from the TiO2 electrode. Owing to the absence of the insulating layer of dried polyelectrolytes, the ZnO/TiO2 all-nanoparticle heterojunction films were expected to be used in the photoelectrochemical device before calcination. PMID:24670479

  10. Improved charge transfer and photoelectrochemical performance of CuI/Sb2S3/TiO2 heterostructure nanotube arrays.

    PubMed

    Yang, Feng; Xi, Jinfang; Gan, Li-Yong; Wang, Yushu; Lu, Shuangwei; Ma, Wenli; Cai, Fanggong; Zhang, Yong; Cheng, Cuihua; Zhao, Yong

    2016-02-15

    Charge transfer is important for the performance of a photoelectrochemical cell. Understanding photogenerated charge accumulation and separation is mandatory for the design and optimisation of photoelectrochemical cells. Unique stacked and embedded heterostructure of Sb2S3/TiO2 nanotube arrays (NTAs) was fabricated through anodic oxidation with the hydrothermal method. Surface photovoltage spectroscopy, phase spectra and photoluminescence measurements were performed to explore the mechanism by which the inorganic hole transport material CuI affects the charge transfer and photoelectrochemical properties of Sb2S3/TiO2 heterostructure NTAs. The interfacial separation and transport of photoinduced charge carriers were also examined by applying current-voltage characteristics (J-V), incident-photon-to-current conversion efficiency (IPCE) and Mott-Schottky techniques. Results show that CuI acts not only as a hole-conducting and electron-blocking material but also as a light-absorbing material in the ultraviolet range. Efficient charge transfer processes exist in CuI/Sb2S3/TiO2 heterostructure NTAs. The photoelectrochemical performance of CuI/Sb2S3/TiO2 heterostructure NTAs is dramatically improved. Under AM 1.5G illumination at 100mW/cm(2), the short-circuit current density and open-circuit voltage are 3.51mA/cm(2) and 0.87V, respectively. The photoelectric conversion efficiency of CuI/Sb2S3/TiO2 heterostructure NTAs (0.95%) is 36% higher than that of Sb2S3/TiO2 heterostructure NTAs (0.66%). PMID:26598949

  11. Auxiliary pattern for cell-based OPC

    NASA Astrophysics Data System (ADS)

    Kahng, Andrew B.; Park, Chul-Hong

    2006-10-01

    The runtime of model-based optical proximity correction (OPC) tools has grown unacceptably with each successive technology generation, and has emerged as one of the major bottlenecks for turnaround time (TAT) of IC data preparation and manufacturing. The cell-based OPC approach improves runtime by performing OPC once per cell definition as opposed to once per cell instantiation in the layout. However, cell-based OPC does not comprehend inter-cell optical interactions that affect feature printability in a layout context. In this work, we propose auxiliary pattern-enabled cell-based OPC which can minimize the CD differences between cell-based OPC and model-based OPC. To enable effective insertion of auxiliary pattern (AP) in the design, we also propose a post-placement optimization of a standard cell block with respect to detailed placement. By dynamic programming-based placement perturbation, we achieve 100% AP applicability in designs with placement utilizations of < 70%. In an evaluation with a complete industrial flow, cell-based OPC with AP can match gate edge placement error (EPE) count of model-based OPC within 4%. This is an improvement of 90%, on average, over cell-based OPC without APs. The AP-based OPC approach can reduce OPC runtimes versus model-based OPC by up to 40X in our benchmark designs. We can also achieve reduction of GDSII file size and ORC runtimes due to hierarchy maintenance of cell-based OPC.

  12. High-throughput synthesis and screening of photon absorbers and photocatalysts for solar fuel cells

    NASA Astrophysics Data System (ADS)

    Mitrovic, Slobodan; Marcin, Martin; Lin, Sean; Jin, Jian

    2012-02-01

    Joint Center for Artificial Photosynthesis is a D.O.E. Energy Innovation Hub conceived to develop solar fuel cell technologies by bringing together the critical mass of scientist and engineers nationwide. The High-Throughput Experimentation group at JCAP is developing pipelines for accelerated discovery of new materials - photon absorbers, photoelectrochemical and electrochemical catalysts - using combinatorial approaches (ink-jet, sol-gel, physical vapor deposition). Thin films of semiconducting metal-oxides, sulfides, nitrides and phosphides are synthesized and screened in high-throughput according to their optical and photoelectrochemical properties, as well as structure and phase. Vast libraries of materials and data are generated and made available to inside and outside research groups. Here we present data on binary, ternary and quaternary metal-oxide systems prepared by the ink-jet technology. The systems include tungsten-based photo-absorbers and nickel-iron-based catalysts for water splitting.

  13. Orientation modulated charge transport in hematite for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Cai, Jiajia; Liu, Yinglei; Li, Song; Gao, Meiqi; Wang, Dunwei; Qin, Gaowu

    2016-05-01

    Hematite is currently considered one of the most promising photoanode materials for light-driven water splitting. The photoelectrochemical performance of hematite is limited by its low conductivity. In this work, we demonstrate that the conductivity of hematite films can be tuned by controlling the orientation of hematite crystals. By applying a high magnetic field (up to 10 T) during the drop-casting preparation, hematite films composed of single crystal particles show featured texture by promoting those particles alignment with (001) normal to the substrate. By enhancing the photocurrent densities with tuned hematite orientation, the current method provides an effective way for increasing the number of carriers that can reach the surface.

  14. Photoelectrochemical fabrication of sawtooth gratings in n-GaAs

    NASA Technical Reports Server (NTRS)

    Carrabba, Michael M.; Nguyen, Nguyet M.; Rauh, R. David

    1986-01-01

    A photoelectrochemical approach is employed to fabricate exceptionally smooth low-pitch grating structures consisting of polished single crystals of (100) oriented n-GaAs in a sawtooth profile. The depth of the edged features is controlled by monitoring the total coulombs passed, and the rate of etching is precisely controlled by the light intensity, minimizing diffusional gradients in the liquid which may impair the uniformity. Symmetrical grooves spaced 10 microns apart will have a depth of 7.14 microns, and typically, 10-20 percent less total charge is required.

  15. Conformal Cu2S-coated Cu2O nanostructures grown by ion exchange reaction and their photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Minguez-Bacho, Ignacio; Courté, Marc; Fan, Hong Jin; Fichou, Denis

    2015-05-01

    Cuprous oxide Cu2O is a promising p-type semiconductor for photoelectrochemical (PEC) solar hydrogen generation because it has a suitable bandgap (Eg = 2.0-2.2 eV) and a band alignment adapted to water reduction. In addition, metallic Cu is earth-abundant thus making Cu2O a low-cost material. However, the reduction potential of Cu2O into metallic Cu (0.47 V versus RHE) is lower than that of water which induces a severe instability under irradiation in a PEC cell. Therefore, our recent efforts focused on the growth of a protective overlayer on top of Cu2O in order to stabilize Cu2O when used as a photocathode in an aqueous electrolyte. Among potential protective materials cuprous sulphide Cu2S is another p-type semiconductor with a 1.2 eV bandgap and an appropriate energy level alignment with Cu2O that would allow electrons flowing to the interface. We present here an original and simple method aimed at protecting a compact layer (CL) or nanowires (NWs) of Cu2O with a Cu2S coating. Our method is based on the ions exchange reaction (IER) of O2- into S2- at the surface of Cu2O itself in a solution-containing Na2S as the sulphur source. The local surface IER implies the formation of a conformal and uniform coating independently on the starting Cu2O morphology, CLs or NWs. As expected, coating Cu2O photocathodes by a conformal Cu2S layer improves their stability and PEC performances.

  16. Conformal Cu2S-coated Cu2O nanostructures grown by ion exchange reaction and their photoelectrochemical properties.

    PubMed

    Minguez-Bacho, Ignacio; Courté, Marc; Fan, Hong Jin; Fichou, Denis

    2015-05-01

    Cuprous oxide Cu2O is a promising p-type semiconductor for photoelectrochemical (PEC) solar hydrogen generation because it has a suitable bandgap (Eg = 2.0-2.2 eV) and a band alignment adapted to water reduction. In addition, metallic Cu is earth-abundant thus making Cu2O a low-cost material. However, the reduction potential of Cu2O into metallic Cu (0.47 V versus RHE) is lower than that of water which induces a severe instability under irradiation in a PEC cell. Therefore, our recent efforts focused on the growth of a protective overlayer on top of Cu2O in order to stabilize Cu2O when used as a photocathode in an aqueous electrolyte. Among potential protective materials cuprous sulphide Cu2S is another p-type semiconductor with a 1.2 eV bandgap and an appropriate energy level alignment with Cu2O that would allow electrons flowing to the interface. We present here an original and simple method aimed at protecting a compact layer (CL) or nanowires (NWs) of Cu2O with a Cu2S coating. Our method is based on the ions exchange reaction (IER) of O(2-) into S(2-) at the surface of Cu2O itself in a solution-containing Na2S as the sulphur source. The local surface IER implies the formation of a conformal and uniform coating independently on the starting Cu2O morphology, CLs or NWs. As expected, coating Cu2O photocathodes by a conformal Cu2S layer improves their stability and PEC performances. PMID:25865464

  17. 3D Bi2S3/TiO2 cross-linked heterostructure: An efficient strategy to improve charge transport and separation for high photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Han, Minmin; Jia, Junhong

    2016-10-01

    A novel 3D cross-linked heterostructure of TiO2 nanorods connecting with each other via ultrathin Bi2S3 nanosheets is constructed by a facile and effective strategy. The growth mechanism has been investigated and proposed based on the evolution of microstructure by changing the reaction parameters. Benefiting from the unique cross-linked heterostructure, the as-prepared Bi2S3 nanosheets modified TiO2 nanorods arrays could achieve a high energy conversion efficiency of 3.29% which is the highest value to date for Bi2S3-only sensitized solar cells as the reported highest value is 2.23% and other reported values are less than 1%. Furthermore, the photoelectrochemical studies clearly reveal that the novel cross-linked heterostructure exhibits much better activity than 0D nanoparticles decorated TiO2 nanorods under visible light irradiation, which may be primarily ascribed to the efficient electron transfer from 2D ultrathin Bi2S3 nanosheets to 1D TiO2 nanorod arrays. The promising results in this work confirm the advantages of cross-linked heterostructure and also undoubtedly offer an attractive synthesis strategy to fabricate other nanorod-based hierarchical architecture as well as nano-devices for solar energy conversion.

  18. Fabrication and photoelectrochemical properties of ordered Si nanohole arrays

    NASA Astrophysics Data System (ADS)

    Ji, Jiuyu; Zhang, Heqiu; Qiu, Yu; Wang, Lina; Wang, Yan; Hu, Lizhong

    2014-02-01

    Large-area highly ordered silicon nanohole (SiNH) arrays on Si substrate have been fabricated by the combination of nanosphere lithography and metal assisted electroless etching. The diameter, length of nanoholes, and the center-to-center distance of adjacent nanoholes, can be accurately controlled by nanosphere lithography and metal assisted electroless etching conditions. The sub-wavelength structure of SiNH arrays had excellent antireflection property with a low reflectance of 3.5% within the wavelength range of 300-1000 nm. Compared to the planar Si, the SiNH samples exhibited a higher photoelectrochemical hydrogen generation performance. The improved performance was attributed to SiNH arrays providing an effective light-trapping and a higher semiconductor/electrolyte interface areas which reduce the overpotential required for photoelectrochemical hydrogen reaction. Furthermore, decorating the SiNH arrays with platinum nanoparticles (PtNPs) yielded a significantly high photovoltage of 0.12 V. The photoconversion efficiency of Pt-decorated SiNH (Pt/SiNH) arrays was 22% under the illumination of 100 mW/cm2, higher than that of SiNH arrays (15.5%) and the planar Si (8.1%).

  19. Photoelectrochemical Hydrogen Production Using New Combinatorial Chemistry Derived Materials

    SciTech Connect

    Jaramillo, Thomas F.; Baeck, Sung-Hyeon; Kleiman-Shwarsctein, Alan; Stucky, Galen D.; McFarland, Eric W.

    2004-10-25

    Solar photoelectrochemical water-splitting has long been viewed as one of the “holy grails” of chemistry because of its potential impact as a clean, renewable method of fuel production. Several known photocatalytic semiconductors can be used; however, the fundamental mechanisms of the process remain poorly understood and no known material has the required properties for cost effective hydrogen production. In order to investigate morphological and compositional variations in metal oxides as they relate to opto-electrochemical properties, we have employed a combinatorial methodology using automated, high-throughput, electrochemical synthesis and screening together with conventional solid-state methods. This report discusses a number of novel, high-throughput instruments developed during this project for the expeditious discovery of improved materials for photoelectrochemical hydrogen production. Also described within this report are results from a variety of materials (primarily tungsten oxide, zinc oxide, molybdenum oxide, copper oxide and titanium dioxide) whose properties were modified and improved by either layering, inter-mixing, or doping with one or more transition metals. Furthermore, the morphologies of certain materials were also modified through the use of structure directing agents (SDA) during synthesis to create mesostructures (features 2-50 nm) that increased surface area and improved rates of hydrogen production.

  20. Infra-red photoresponse of mesoscopic NiO-based solar cells sensitized with PbS quantum dot

    PubMed Central

    Raissi, Mahfoudh; Pellegrin, Yann; Jobic, Stéphane; Boujtita, Mohammed; Odobel, Fabrice

    2016-01-01

    Sensitized NiO based photocathode is a new field of investigation with increasing scientific interest in relation with the development of tandem dye-sensitized solar cells (photovoltaic) and dye-sensitized photoelectrosynthetic cells (solar fuel). We demonstrate herein that PbS quantum dots (QDs) represent promising inorganic sensitizers for NiO-based quantum dot-sensitized solar cells (QDSSCs). The solar cell sensitized with PbS quantum dot exhibits significantly higher photoconversion efficiency than solar cells sensitized with a classical and efficient molecular sensitizer (P1 dye = 4-(Bis-{4-[5-(2,2-dicyano-vinyl)-thiophene-2-yl]-phenyl}-amino)-benzoic acid). Furthermore, the system features an IPCE (Incident Photon-to-Current Efficiency) spectrum that spreads into the infra-red region, reaching operating wavelengths of 950 nm. The QDSSC photoelectrochemical device works with the complexes tris(4,4′-ditert-butyl-2,2′-bipyridine)cobalt(III/II) redox mediators, underscoring the formation of a long-lived charge-separated state. The electrochemical impedance spectrocopy measurements are consistent with a high packing of the QDs upon the NiO surface, the high density of which limits the access of the electrolyte and results in favorable light absorption cross-sections and a significant hole lifetime. These notable results highlight the potential of NiO-based photocathodes sensitized with quantum dots for accessing and exploiting the low-energy part of the solar spectrum in photovoltaic and photocatalysis applications. PMID:27125454

  1. Infra-red photoresponse of mesoscopic NiO-based solar cells sensitized with PbS quantum dot

    NASA Astrophysics Data System (ADS)

    Raissi, Mahfoudh; Pellegrin, Yann; Jobic, Stéphane; Boujtita, Mohammed; Odobel, Fabrice

    2016-04-01

    Sensitized NiO based photocathode is a new field of investigation with increasing scientific interest in relation with the development of tandem dye-sensitized solar cells (photovoltaic) and dye-sensitized photoelectrosynthetic cells (solar fuel). We demonstrate herein that PbS quantum dots (QDs) represent promising inorganic sensitizers for NiO-based quantum dot-sensitized solar cells (QDSSCs). The solar cell sensitized with PbS quantum dot exhibits significantly higher photoconversion efficiency than solar cells sensitized with a classical and efficient molecular sensitizer (P1 dye = 4-(Bis-{4-[5-(2,2-dicyano-vinyl)-thiophene-2-yl]-phenyl}-amino)-benzoic acid). Furthermore, the system features an IPCE (Incident Photon-to-Current Efficiency) spectrum that spreads into the infra-red region, reaching operating wavelengths of 950 nm. The QDSSC photoelectrochemical device works with the complexes tris(4,4‧-ditert-butyl-2,2‧-bipyridine)cobalt(III/II) redox mediators, underscoring the formation of a long-lived charge-separated state. The electrochemical impedance spectrocopy measurements are consistent with a high packing of the QDs upon the NiO surface, the high density of which limits the access of the electrolyte and results in favorable light absorption cross-sections and a significant hole lifetime. These notable results highlight the potential of NiO-based photocathodes sensitized with quantum dots for accessing and exploiting the low-energy part of the solar spectrum in photovoltaic and photocatalysis applications.

  2. Infra-red photoresponse of mesoscopic NiO-based solar cells sensitized with PbS quantum dot.

    PubMed

    Raissi, Mahfoudh; Pellegrin, Yann; Jobic, Stéphane; Boujtita, Mohammed; Odobel, Fabrice

    2016-01-01

    Sensitized NiO based photocathode is a new field of investigation with increasing scientific interest in relation with the development of tandem dye-sensitized solar cells (photovoltaic) and dye-sensitized photoelectrosynthetic cells (solar fuel). We demonstrate herein that PbS quantum dots (QDs) represent promising inorganic sensitizers for NiO-based quantum dot-sensitized solar cells (QDSSCs). The solar cell sensitized with PbS quantum dot exhibits significantly higher photoconversion efficiency than solar cells sensitized with a classical and efficient molecular sensitizer (P1 dye = 4-(Bis-{4-[5-(2,2-dicyano-vinyl)-thiophene-2-yl]-phenyl}-amino)-benzoic acid). Furthermore, the system features an IPCE (Incident Photon-to-Current Efficiency) spectrum that spreads into the infra-red region, reaching operating wavelengths of 950 nm. The QDSSC photoelectrochemical device works with the complexes tris(4,4'-ditert-butyl-2,2'-bipyridine)cobalt(III/II) redox mediators, underscoring the formation of a long-lived charge-separated state. The electrochemical impedance spectrocopy measurements are consistent with a high packing of the QDs upon the NiO surface, the high density of which limits the access of the electrolyte and results in favorable light absorption cross-sections and a significant hole lifetime. These notable results highlight the potential of NiO-based photocathodes sensitized with quantum dots for accessing and exploiting the low-energy part of the solar spectrum in photovoltaic and photocatalysis applications. PMID:27125454

  3. Infra-red photoresponse of mesoscopic NiO-based solar cells sensitized with PbS quantum dot.

    PubMed

    Raissi, Mahfoudh; Pellegrin, Yann; Jobic, Stéphane; Boujtita, Mohammed; Odobel, Fabrice

    2016-04-29

    Sensitized NiO based photocathode is a new field of investigation with increasing scientific interest in relation with the development of tandem dye-sensitized solar cells (photovoltaic) and dye-sensitized photoelectrosynthetic cells (solar fuel). We demonstrate herein that PbS quantum dots (QDs) represent promising inorganic sensitizers for NiO-based quantum dot-sensitized solar cells (QDSSCs). The solar cell sensitized with PbS quantum dot exhibits significantly higher photoconversion efficiency than solar cells sensitized with a classical and efficient molecular sensitizer (P1 dye = 4-(Bis-{4-[5-(2,2-dicyano-vinyl)-thiophene-2-yl]-phenyl}-amino)-benzoic acid). Furthermore, the system features an IPCE (Incident Photon-to-Current Efficiency) spectrum that spreads into the infra-red region, reaching operating wavelengths of 950 nm. The QDSSC photoelectrochemical device works with the complexes tris(4,4'-ditert-butyl-2,2'-bipyridine)cobalt(III/II) redox mediators, underscoring the formation of a long-lived charge-separated state. The electrochemical impedance spectrocopy measurements are consistent with a high packing of the QDs upon the NiO surface, the high density of which limits the access of the electrolyte and results in favorable light absorption cross-sections and a significant hole lifetime. These notable results highlight the potential of NiO-based photocathodes sensitized with quantum dots for accessing and exploiting the low-energy part of the solar spectrum in photovoltaic and photocatalysis applications.

  4. In situ formation of p-n junction: a novel principle for photoelectrochemical sensor and its application for mercury(II) ion detection.

    PubMed

    Wang, Guang-Li; Liu, Kang-Li; Dong, Yu-Ming; Li, Zai-Jun; Zhang, Chi

    2014-05-27

    The discovery and development of photoelectrochemical sensors with novel principles are of great significance to realize sensitive and low-cost detection. In this paper, a new photoelectrochemial sensor based on the in situ formation of p-n junction was designed and used for the accurate determination of mercury(II) ions. Cysteine-capped ZnS quantum dots (QDs) was assembled on the surface of indium tin oxide (ITO) electrode based on the electrostatic interaction between Poly(diallyldimethylammonium chloride) (PDDA) and Cys-capped ZnS QDs. The in situ formation of HgS, a p-type semiconductor, on the surface of ZnS facilitated the charge carrier transport and promoted electron-hole separation, triggered an obviously enhanced anodic photocurrent of Cys-capped ZnS QDs. The formation of p-n junction was confirmed by P-N conductive type discriminator measurements and current-voltage (I-V) curves. The photoelectrochemical method was used for the sensing of trace mercuric (II) ions with a linear concentration of 0.01 to 10.0 µM and a detection limit of 4.6×10(-9)mol/L. It is expected that the present study can serve as a foundation to the application of p-n heterojunction to photoelectrochemical sensors and it might be easily extended to more exciting sensing systems by photoelectrochemistry. PMID:24832992

  5. A three-dimensional interconnected hierarchical FeOOH/TiO₂/ZnO nanostructural photoanode for enhancing the performance of photoelectrochemical water oxidation.

    PubMed

    Li, Zhenhu; Feng, Shuanglong; Liu, Shuangyi; Li, Xin; Wang, Liang; Lu, Wenqiang

    2015-12-01

    A novel ZnO/TiO2/FeOOH hierarchical nanostructure has been synthesized by a low temperature chemical bath deposition method. The integrated three-dimensional (3D) nanostructure consists of one-dimensional (1D) ZnO/TiO2 core-shell nanowire arrays and two-dimensional (2D) interconnected FeOOH nanosheets. By applying such a hierarchical nanostructure as a photoanode for photoelectrochemical water reaction, higher photostability and photocurrent density are gained compared with the reported ZnO based nanostructures. It is concluded that the giant enhancement of the properties is because, in the process of photoelectrochemical reaction, electron-hole separation and transfer are enhanced efficiently through the ZnO/TiO2 heterojunction, and in the meanwhile, terminal interconnected FeOOH nanosheets play both the roles of a surface catalyst and a protective layer effectively to accelerate water splitting reaction and enhance photostability. Based on such an environmentally friendly hierarchical nanostructure, photoelectrochemical water splitting and other similar reactions could be performed effectively and economically. PMID:26523803

  6. Nanoparticle-based monitoring of cell therapy

    PubMed Central

    Xu, Chenjie; Mu, Luye; Roes, Isaac; Miranda-Nieves, David; Nahrendorf, Matthias; Ankrum, James A; Zhao, Weian; Karp, Jeffrey M

    2012-01-01

    Exogenous cell therapy aims to replace/repair diseased or dysfunctional cells and promises to revolutionize medicine by restoring tissue and organ function. To develop effective cell therapy, the location, distribution and long-term persistence of transplanted cells must be evaluated. Nanoparticle (NP) based imaging technologies have the potential to track transplanted cells non-invasively. Here we summarize the most recent advances in NP-based cell tracking with emphasis on (1) the design criteria for cell tracking NPs, (2) protocols for cell labeling, (3) a comparison of available imaging modalities and their corresponding contrast agents, (4) a summary of preclinical studies on NP-based cell tracking and finally (5) perspectives and future directions. PMID:22101191

  7. Rice-like brookite titania as an efficient scattering layer for nanosized anatase titania film-based dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xu, Jinlei; Li, Kan; Shi, Wenye; Li, Renjie; Peng, Tianyou

    2014-08-01

    Rice-like brookite TiO2 particles with high phase purity and ∼600 nm particle diameter were synthesized through a hydrothermal method, and then bilayer TiO2 film-based dye-sensitized solar cells (DSSCs) were fabricated by using photoanode consisting of nanosized anatase TiO2 film as underlayer and the above brookite TiO2 submicrometer particle film as overlayer. The effects of the brookite overlayer on the light scattering and photoelectrochemical performances of the anatase TiO2 film-based DSSCs were investigated by using UV-vis diffused reflectance absorption spectra (DRS), open-circuit voltage decay (OCVD) curves and electrochemical impedance spectra (EIS) measurements. It is found that the bilayer film-based DSSCs have much better light harvesting capability, higher open-circuit voltage and longer electron lifetimes than the single anatase TiO2 film-based one. After optimizing the thicknesses of underlayer and overlayer, the corresponding bilayer TiO2 film-based DSSC gives conversion efficiency up to 8.83%, with a 29% improvement in the efficiency as compared to that (6.82%) of the single film-based one under AM 1.5G one sun irradiation. The present results represent a clear advance towards efficient light scattering materials for the nanosized TiO2 film-based solar cells with low-cost and high efficiency.

  8. Construction of inorganic-organic 2D/2D WO₃/g-C₃N₄ nanosheet arrays toward efficient photoelectrochemical splitting of natural seawater.

    PubMed

    Li, Yuangang; Wei, Xiaoliang; Yan, Xiangyang; Cai, Jiangtao; Zhou, Anning; Yang, Mengru; Liu, Kaiqiang

    2016-04-21

    Hydrogen production from seawater and solar energy based on photoelectrochemical cells is extremely attractive due to earth-abundance of seawater and solar radiation. Herein, we report the successful fabrication of novel inorganic-organic 2D/2D WO3/g-C3N4 nanosheet arrays (WO3/g-C3N4 NSAs) grown on a FTO substrate via a facile hydrothermal growth and deposition-annealing process, and their application in natural seawater splitting. The results indicate that the WO3/g-C3N4 NSAs exhibit a photocurrent density of 0.73 mA cm(-2) at 1.23 V versus RHE under AM 1.5G (100 mW cm(-2)) illumination, which is 2-fold higher than that of WO3 NSAs. More importantly, the WO3/g-C3N4 NSA photoanode is quite stable during seawater splitting and the photocurrent density does not substantially decrease after continuous illumination for 3600 s. The remarkably enhanced performance originates primarily from the formation of the WO3/g-C3N4 heterojunction between WO3 and g-C3N4 nanosheets, which accelerates charge transfer and separation, and prolongs the lifetime of electrons as demonstrated by EIS and Mott-Schottky analyses. Finally, a possible mechanism for the improved performance was proposed and discussed. PMID:27022001

  9. Highly stable tandem solar cell monolithically integrating dye-sensitized and CIGS solar cells

    NASA Astrophysics Data System (ADS)

    Chae, Sang Youn; Park, Se Jin; Joo, Oh-Shim; Jun, Yongseok; Min, Byoung Koun; Hwang, Yun Jeong

    2016-08-01

    A highly stable monolithic tandem solar cell was developed by combining the heterogeneous photovoltaic technologies of dye-sensitized solar cell (DSSC) and solution-processed CuInxGa1-xSeyS1-y (CIGS) thin film solar cells. The durability of the tandem cell was dramatically enhanced by replacing the redox couple from to [Co(bpy)3]2+ /[Co(bpy)3]3+), accompanied by a well-matched counter electrode (PEDOT:PSS) and sensitizer (Y123). A 1000 h durability test of the DSSC/CIGS tandem solar cell in ambient conditions resulted in only a 5% decrease in solar cell efficiency. Based on electrochemical impedance spectroscopy and photoelectrochemical cell measurement, the enhanced stability of the tandem cell is attributed to minimal corrosion by the cobalt-based polypyridine complex redox couple.

  10. Highly stable tandem solar cell monolithically integrating dye-sensitized and CIGS solar cells

    PubMed Central

    Chae, Sang Youn; Park, Se Jin; Joo, Oh-Shim; Jun, Yongseok; Min, Byoung Koun; Hwang, Yun Jeong

    2016-01-01

    A highly stable monolithic tandem solar cell was developed by combining the heterogeneous photovoltaic technologies of dye-sensitized solar cell (DSSC) and solution-processed CuInxGa1-xSeyS1-y (CIGS) thin film solar cells. The durability of the tandem cell was dramatically enhanced by replacing the redox couple from to [Co(bpy)3]2+ /[Co(bpy)3]3+), accompanied by a well-matched counter electrode (PEDOT:PSS) and sensitizer (Y123). A 1000 h durability test of the DSSC/CIGS tandem solar cell in ambient conditions resulted in only a 5% decrease in solar cell efficiency. Based on electrochemical impedance spectroscopy and photoelectrochemical cell measurement, the enhanced stability of the tandem cell is attributed to minimal corrosion by the cobalt-based polypyridine complex redox couple. PMID:27489138

  11. Synthesis and photoelectrochemical properties of CdWO4 and CdS/CdWO4 nanostructures

    NASA Astrophysics Data System (ADS)

    Xu, Weina; Zheng, Chunhua; Hua, Hao; Yang, Qi; Chen, Lin; Xi, Yi; Hu, Chenguo

    2015-02-01

    A facile composite-salt-mediated strategy is employed for the first time to synthesize CdWO4 nanowire and nanoflower arrays on cadmium foil substrates. The photoelectrochemical (PEC) properties are measured on the electrodes made of the CdWO4 nanowire and nanoflower arrays under the simulated sunlight illumination. Both electrodes display high sensitive response and photocurrent stability. The photocurrent density of the nanowire arrays electrode reach 0.35 mA/cm2, which is about 3 times as much as that of the nanoflower array electrode. To improve the visible light photocurrent response, CdS nanoparticles are deposited on the CdWO4 nanowire arrays to form a CdS/CdWO4 heterojunction. Remarkably enhanced photoresponse is observed on the CdS/CdWO4 heterostructure and the photocurrent intensity is about twice as much as that of the electrode made of the pure CdWO4 nanowire arrays. The photoelectric mechanism is also discussed by the crystal structure and morphology characterization, optical band gap and carrier mobility analysis. This work presents a new design of a photoelectrochemical device for possible applications in photoelectrolysis of water and solar cells or highly sensitive light detection.

  12. Cell or Cell Membrane-Based Drug Delivery Systems

    PubMed Central

    Tan, Songwei; Wu, Tingting; Zhang, Dan; Zhang, Zhiping

    2015-01-01

    Natural cells have been explored as drug carriers for a long period. They have received growing interest as a promising drug delivery system (DDS) until recently along with the development of biology and medical science. The synthetic materials, either organic or inorganic, are found to be with more or less immunogenicity and/or toxicity. The cells and extracellular vesicles (EVs), are endogenous and thought to be much safer and friendlier. Furthermore, in view of their host attributes, they may achieve different biological effects and/or targeting specificity, which can meet the needs of personalized medicine as the next generation of DDS. In this review, we summarized the recent progress in cell or cell membrane-based DDS and their fabrication processes, unique properties and applications, including the whole cells, EVs and cell membrane coated nanoparticles. We expect the continuing development of this cell or cell membrane-based DDS will promote their clinic applications. PMID:26000058

  13. Colloidal TiO2 nanocrystals/MEH-PPV nanocomposites: photo(electro)chemical study.

    PubMed

    Petrella, Andrea; Tamborra, Michela; Curri, M Lucia; Cosma, Pinalysa; Striccoli, Marinella; Cozzoli, P Davide; Agostiano, Angela

    2005-02-01

    An extensive optical and photoelectrochemical study of blended systems composed of organic-capped TiO(2) nanocrystals with either a spherical or rodlike morphology and a conjugated polymer, MEH-PPV, is presented. The absorption and emission properties of the heterojunctions have been characterized both in solution and in thin films. The blended structures deposited onto conductive substrates have been employed as active layers in photoelectrochemical systems. The investigation has been focused on the photoinduced charge transfer and recombination processes at the interface between the two components, as a function of the nanocrystal shape and surface coating, and of the film thickness. The presence of a large number of interfaces available for charge transfer is believed to play a fundamental role in enhancing the photoelectrochemical performances of the dispersed heterojunctions. The reported results suggest that such MEH-PPV/TiO(2) heterojunctions may be exploited as potential active layers in future photovoltaic and photoelectrochemical devices. PMID:16851127

  14. Colloidal TiO2 nanocrystals/MEH-PPV nanocomposites: photo(electro)chemical study.

    PubMed

    Petrella, Andrea; Tamborra, Michela; Curri, M Lucia; Cosma, Pinalysa; Striccoli, Marinella; Cozzoli, P Davide; Agostiano, Angela

    2005-02-01

    An extensive optical and photoelectrochemical study of blended systems composed of organic-capped TiO(2) nanocrystals with either a spherical or rodlike morphology and a conjugated polymer, MEH-PPV, is presented. The absorption and emission properties of the heterojunctions have been characterized both in solution and in thin films. The blended structures deposited onto conductive substrates have been employed as active layers in photoelectrochemical systems. The investigation has been focused on the photoinduced charge transfer and recombination processes at the interface between the two components, as a function of the nanocrystal shape and surface coating, and of the film thickness. The presence of a large number of interfaces available for charge transfer is believed to play a fundamental role in enhancing the photoelectrochemical performances of the dispersed heterojunctions. The reported results suggest that such MEH-PPV/TiO(2) heterojunctions may be exploited as potential active layers in future photovoltaic and photoelectrochemical devices.

  15. Effect of charge compensation on the photoelectrochemical properties of Ho-doped SrTiO{sub 3} films

    SciTech Connect

    Zhao, Long; Fang, Liang; Dong, Wen; Zheng, Fengang; Shen, Mingrong; Wu, Tom

    2013-03-25

    When Ho{sup 3+} ions are substituted at Sr{sup 2+} sites in SrTiO{sub 3} (STO), the excess positive charges are compensated via three complementary routes: (1) strontium vacancies, (2) titanium vacancies, and (3) conduction electrons. In this study, we show that the photoelectrochemical properties of Ho-doped STO films are dependent on the charge compensation mechanisms. The compensation mechanism via the titanium vacancies exhibits the highest photocurrent density, which is 1.7 times higher than that of the pure STO sample. Based on the measured dielectric properties and electrochemical impedance spectroscopy data, we propose that the enhanced dielectric constant of the films can enlarge the width of the space charge region at the film/liquid interface, which eventually leads to the increase of the photocurrent density. Further enhancement of photocurrent density is obtained in the samples decorated with appropriate amounts of Pt nanoparticles, showing the advantage of composites for achieving the efficient photoelectrochemical property.

  16. Improving cell-based therapies by nanomodification.

    PubMed

    Chen, Wei; Fu, Liwu; Chen, Xiaoyuan

    2015-12-10

    Cell-based therapies are emerging as a promising approach for various diseases. Their therapeutic efficacy depends on rational control and regulation of the functions and behaviors of cells during their treatments. Different from conventional regulatory strategy by chemical adjuvants or genetic engineering, which is restricted by limited synergistic regulatory efficiency or uncertain safety problems, a novel approach based on nanoscale artificial materials can be applied to modify living cells to endow them with novel functions and unique properties. Inspired by natural "nano shell" and "nano compass" structures, cell nanomodification can be developed through both external and internal pathways. In this review, some novel cell surface engineering and intracellular nanoconjugation strategies are summarized. Their potential applications are also discussed, including cell protection, cell labeling, targeted delivery and in situ regulation. It is believed that these novel cell-material complexes can have great potentials for biomedical applications. PMID:26423238

  17. Semiconductor nanowires for photovoltaic and photoelectrochemical energy conversion

    SciTech Connect

    Dasgupta, Neil; Yang, Peidong

    2013-01-23

    Semiconductor nanowires (NW) possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for wide-scale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional (1D) structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.

  18. Photoelectrochemical hydrogen production from biomass derivatives and water.

    PubMed

    Lu, Xihong; Xie, Shilei; Yang, Hao; Tong, Yexiang; Ji, Hongbing

    2014-11-21

    Hydrogen, a clean energy carrier with high energy capacity, is a very promising candidate as a primary energy source for the future. Photoelectrochemical (PEC) hydrogen production from renewable biomass derivatives and water is one of the most promising approaches to producing green chemical fuel. Compared to water splitting, hydrogen production from renewable biomass derivatives and water through a PEC process is more efficient from the viewpoint of thermodynamics. Additionally, the carbon dioxide formed can be re-transformed into carbohydrates via photosynthesis in plants. In this review, we focus on the development of photoanodes and systems for PEC hydrogen production from water and renewable biomass derivatives, such as methanol, ethanol, glycerol and sugars. We also discuss the future challenges and opportunities for the design of the state-of-the-art photoanodes and PEC systems for hydrogen production from biomass derivatives and water.

  19. Electrophoretic Deposition of Carbon Nitride Layers for Photoelectrochemical Applications.

    PubMed

    Xu, Jingsan; Shalom, Menny

    2016-05-25

    Electrophoretic deposition (EPD) is used for the growth of carbon nitride (C3N4) layers on conductive substrates. EPD is fast, environmentally friendly, and allows the deposition of negatively charged C3N4 with different compositions and chemical properties. In this method, C3N4 can be deposited on various conductive substrates ranging from conductive glass and carbon paper to nickel foam possessing complex 3D geometries. The high flexibility of this approach enables us to readily tune the photophysical and photoelectronic properties of the C3N4 electrodes. The advantage of this method was further illustrated by the tailored construction of a heterostructure between two complementary C3N4, with marked photoelectrochemical activity.

  20. Polyaniline films photoelectrochemically reduce CO2 to alcohols.

    PubMed

    Hursán, Dorottya; Kormányos, Attila; Rajeshwar, Krishnan; Janáky, Csaba

    2016-07-01

    In this communication, we demonstrate that polyaniline, the very first example of an organic semiconductor, is a promising photocathode material for the conversion of carbon dioxide (CO2) to alcohol fuels. CO2 is a greenhouse gas; thus using solar energy to convert CO2 to transportation fuels (such as methanol or ethanol) is a value-added approach to simultaneous generation of alternative fuels and environmental remediation of carbon emissions. Insights into its unique behavior obtained from photoelectrochemical measurements and adsorption studies, together with spectroscopic data, are presented. Through a comparative study involving various conducting polymers, a set of criteria is developed for an organic semiconductor to function as a photocathode for generation of solar fuels from CO2. PMID:27345191

  1. Efficient Photoelectrochemical Energy Conversion using Spinach Photosystem II (PSII) in Lipid Multilayer Films.

    PubMed

    Zhang, Yun; Magdaong, Nikki M; Shen, Min; Frank, Harry A; Rusling, James F

    2015-04-01

    The need for clean, renewable energy has fostered research into photovoltaic alternatives to silicon solar cells. Pigment-protein complexes in green plants convert light energy into chemical potential using redox processes that produce molecular oxygen. Here, we report the first use of spinach protein photosystem II (PSII) core complex in lipid films in photoelectrochemical devices. Photocurrents were generated from PSII in a ∼2 μm biomimetic dimyristoylphosphatidylcholine (DMPC) film on a pyrolytic graphite (PG) anode with PSII embedded in multiple lipid bilayers. The photocurrent was ∼20 μA cm(-2) under light intensity 40 mW cm(-2). The PSII-DMPC anode was used in a photobiofuel cell with a platinum black mesh cathode in perchloric acid solution to give an output voltage of 0.6 V and a maximum output power of 14 μW cm(-2). Part of this large output is related to a five-unit anode-cathode pH gradient. With catholytes at higher pH or no perchlorate, or using an MnO2 oxygen-reduction cathode, the power output was smaller. The results described raise the possibility of using PSII-DMPC films in small portable power conversion devices.

  2. Growth and Photoelectrochemical Energy Conversion of Wurtzite Indium Phosphide Nanowire Arrays.

    PubMed

    Kornienko, Nikolay; Gibson, Natalie A; Zhang, Hao; Eaton, Samuel W; Yu, Yi; Aloni, Shaul; Leone, Stephen R; Yang, Peidong

    2016-05-24

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising strategy to absorb solar energy and directly convert it into a dense storage medium in the form of chemical bonds. The continual development and improvement of individual components of PEC systems is critical toward increasing the solar to fuel efficiency of prototype devices. Within this context, we describe a study on the growth of wurtzite indium phosphide (InP) nanowire (NW) arrays on silicon substrates and their subsequent implementation as light-absorbing photocathodes in PEC cells. The high onset potential (0.6 V vs the reversible hydrogen electrode) and photocurrent (18 mA/cm(2)) of the InP photocathodes render them as promising building blocks for high performance PEC cells. As a proof of concept for overall system integration, InP photocathodes were combined with a nanoporous bismuth vanadate (BiVO4) photoanode to generate an unassisted solar water splitting efficiency of 0.5%. PMID:27124203

  3. Growth and Photoelectrochemical Energy Conversion of Wurtzite Indium Phosphide Nanowire Arrays.

    PubMed

    Kornienko, Nikolay; Gibson, Natalie A; Zhang, Hao; Eaton, Samuel W; Yu, Yi; Aloni, Shaul; Leone, Stephen R; Yang, Peidong

    2016-05-24

    Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising strategy to absorb solar energy and directly convert it into a dense storage medium in the form of chemical bonds. The continual development and improvement of individual components of PEC systems is critical toward increasing the solar to fuel efficiency of prototype devices. Within this context, we describe a study on the growth of wurtzite indium phosphide (InP) nanowire (NW) arrays on silicon substrates and their subsequent implementation as light-absorbing photocathodes in PEC cells. The high onset potential (0.6 V vs the reversible hydrogen electrode) and photocurrent (18 mA/cm(2)) of the InP photocathodes render them as promising building blocks for high performance PEC cells. As a proof of concept for overall system integration, InP photocathodes were combined with a nanoporous bismuth vanadate (BiVO4) photoanode to generate an unassisted solar water splitting efficiency of 0.5%.

  4. Efficient Photoelectrochemical Energy Conversion using Spinach Photosystem II (PSII) in Lipid Multilayer Films

    PubMed Central

    Zhang, Yun; Magdaong, Nikki M; Shen, Min; Frank, Harry A; Rusling, James F

    2015-01-01

    The need for clean, renewable energy has fostered research into photovoltaic alternatives to silicon solar cells. Pigment–protein complexes in green plants convert light energy into chemical potential using redox processes that produce molecular oxygen. Here, we report the first use of spinach protein photosystem II (PSII) core complex in lipid films in photoelectrochemical devices. Photocurrents were generated from PSII in a ∼2 μm biomimetic dimyristoylphosphatidylcholine (DMPC) film on a pyrolytic graphite (PG) anode with PSII embedded in multiple lipid bilayers. The photocurrent was ∼20 μA cm−2 under light intensity 40 mW cm−2. The PSII–DMPC anode was used in a photobiofuel cell with a platinum black mesh cathode in perchloric acid solution to give an output voltage of 0.6 V and a maximum output power of 14 μW cm−2. Part of this large output is related to a five-unit anode–cathode pH gradient. With catholytes at higher pH or no perchlorate, or using an MnO2 oxygen-reduction cathode, the power output was smaller. The results described raise the possibility of using PSII–DMPC films in small portable power conversion devices. PMID:25969807

  5. Microwave assisted novel MoBi2S5 nanoflowers: Synthesis, characterization, photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Pawar, Nita B.; Mali, Sawanta S.; Kharade, Suvarta D.; Kondalkar, Vijay V.; Ghanwat, Vishvanath B.; Khot, Kishorkumar V.; Patil, Pramod S.; Bhosale, Popatrao N.

    2016-11-01

    In the present article, we have studied the effect of post annealing treatment on microstructural, optical and photoelectrochemical (PEC) properties of MoBi2S5 thin films synthesized by microwave assisted technique. The synthesized thin films are vacuum annealed for 4 h at 473 K temperature. The X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and UV-Vis-NIR spectrophotometer techniques were used for characterization of the as deposited and annealed MoBi2S5 thin films. The XRD patterns confirm the synthesized and annealed thin films have nanocrystalline nature with rhombohedral-orthorhombic crystal structure. SEM micrographs indicate that, nanoflowers exhibit sharper end after annealing. The optical absorption study illustrates that the optical band gap energy has been decrease from 2.0 eV to 1.75 eV with annealing. Finally, applicability of synthesized thin films has been checked for PEC property. The J-V curves revealed that synthesized thin film photoanodes are suitable for PEC cell application. As well, used simple, economical method has great potential for synthesis of various thin film materials.

  6. Plasmon-enhanced nanoporous BiVO4 photoanodes for efficient photoelectrochemical water oxidation.

    PubMed

    Gan, Jiayong; Rajeeva, Bharath Bangalore; Wu, Zilong; Penley, Daniel; Liang, Chaolun; Tong, Yexiang; Zheng, Yuebing

    2016-06-10

    Conversion of solar irradiation into chemical fuels such as hydrogen with the use of a photoelectrochemical (PEC) cell is an attractive strategy for green energy. The promising technique of incorporating metal nanoparticles (NPs) in the photoelectrodes is being explored to enhance the performance of the photoelectrodes. In this work, we developed Au-NPs-functionalized nanoporous BiVO4 photoanodes, and utilized the plasmonic effects of Au NPs to enhance the photoresponse. The plasmonic enhancement leads to an AM 1.5 photocurrent of 5.1 ± 0.1 mA cm(-2) at 1.23 V versus a reverse hydrogen electrode. We observed an enhancement of five times with respect to pristine BiVO4 in the photocurrent with long-term stability and high energy-conversion efficiency. The overall performance enhancement is attributed to the synergy between the nanoporous architecture of BiVO4 and the plasmonic effects of Au NPs. Our further study reveals that the commendable photoactivity arises from the different plasmonic effects and co-catalyst effects of Au NPs. PMID:27119335

  7. Plasmon-enhanced nanoporous BiVO4 photoanodes for efficient photoelectrochemical water oxidation

    NASA Astrophysics Data System (ADS)

    Gan, Jiayong; Bangalore Rajeeva, Bharath; Wu, Zilong; Penley, Daniel; Liang, Chaolun; Tong, Yexiang; Zheng, Yuebing

    2016-06-01

    Conversion of solar irradiation into chemical fuels such as hydrogen with the use of a photoelectrochemical (PEC) cell is an attractive strategy for green energy. The promising technique of incorporating metal nanoparticles (NPs) in the photoelectrodes is being explored to enhance the performance of the photoelectrodes. In this work, we developed Au-NPs-functionalized nanoporous BiVO4 photoanodes, and utilized the plasmonic effects of Au NPs to enhance the photoresponse. The plasmonic enhancement leads to an AM 1.5 photocurrent of 5.1 ± 0.1 mA cm‑2 at 1.23 V versus a reverse hydrogen electrode. We observed an enhancement of five times with respect to pristine BiVO4 in the photocurrent with long-term stability and high energy-conversion efficiency. The overall performance enhancement is attributed to the synergy between the nanoporous architecture of BiVO4 and the plasmonic effects of Au NPs. Our further study reveals that the commendable photoactivity arises from the different plasmonic effects and co-catalyst effects of Au NPs.

  8. Photoelectrochemical energy conversion at the conjugated polymer/redox polymer electrolyte interface

    SciTech Connect

    Yohannes, T.; Inganaes, O.

    1996-07-01

    Electrically conducting polymers are interesting for use in potentially low-cost solar energy conversion, and in the early 1980s, they were studied for this application. However, progress was limited by their low conversion efficiencies, and not much work has been done recently. All-solid-state photoelectrochemical cells have been constructed using films of a conducting polymer, poly(3-octylthiophene), and a polymer electrolyte, amorphous polyethylene oxide, complexed with the I{sub 3}{sup {minus}}/I{sup {minus}} redox couple. An open-circuit voltage of 250 mV and a short-circuit current of 0.04 {micro}A/cm{sup 2} were obtained with white light illumination at approximately one sun. During illumination, a cathodic photocurrent was observed, indicating that the neutral poly(3-octylthiophene) behaves as a p-type semiconductor. From the spectral response, the junction responsible for the photocurrent generation is between the conducting polymer and the solid polymer electrolyte. The open-circuit voltage and short-circuit current dependence on intensity and variation of open-circuit voltage with redox couple concentration have also been studied.

  9. Plasmon-enhanced nanoporous BiVO4 photoanodes for efficient photoelectrochemical water oxidation

    NASA Astrophysics Data System (ADS)

    Gan, Jiayong; Bangalore Rajeeva, Bharath; Wu, Zilong; Penley, Daniel; Liang, Chaolun; Tong, Yexiang; Zheng, Yuebing

    2016-06-01

    Conversion of solar irradiation into chemical fuels such as hydrogen with the use of a photoelectrochemical (PEC) cell is an attractive strategy for green energy. The promising technique of incorporating metal nanoparticles (NPs) in the photoelectrodes is being explored to enhance the performance of the photoelectrodes. In this work, we developed Au-NPs-functionalized nanoporous BiVO4 photoanodes, and utilized the plasmonic effects of Au NPs to enhance the photoresponse. The plasmonic enhancement leads to an AM 1.5 photocurrent of 5.1 ± 0.1 mA cm-2 at 1.23 V versus a reverse hydrogen electrode. We observed an enhancement of five times with respect to pristine BiVO4 in the photocurrent with long-term stability and high energy-conversion efficiency. The overall performance enhancement is attributed to the synergy between the nanoporous architecture of BiVO4 and the plasmonic effects of Au NPs. Our further study reveals that the commendable photoactivity arises from the different plasmonic effects and co-catalyst effects of Au NPs.

  10. Photoelectrochemical properties of CdS{sub x}Se{sub 1-x} films

    SciTech Connect

    Murali, K.R.; Thilagavathy, K.; Vasantha, S.; Gopalakrishnan, P.; Rachel Oommen, P.

    2010-04-15

    CdS{sub x}Se{sub 1-x} films of different composition (0 < x < 1) were deposited by pulse plating technique at different duty cycles in the range of 10-50%. The films were polycrystalline and exhibited hexagonal structure. The band gap of the films varies from 1.68 to 2.39 eV as the concentration of CdS increases. Energy Dispersive analysis of X-rays (EDAX) measurements indicate that the composition of the films are nearly the same as that of the precursors considered for the deposition. Atomic force microscopy studies indicated that the grain size increased from 20 to 200 nm as the concentration of CdSe increased. Photoelectrochemical (PEC) cell studies indicated that the films of composition CdS{sub 0.9}Se{sub 0.1} exhibited maximum photoactivity. Mott-Schottky studies indicated that the films exhibit n-type behaviour. Spectral response measurements indicated that the photocurrent maxima occurred at the wavelength value corresponding to the band gap of the films. (author)

  11. Solar-to-Hydrogen Photovoltaic/Photoelectrochemical Devices Using Amorphous Silicon Carbide as the Photoelectrode

    SciTech Connect

    Hu, J.; Zhu, F.; Matulionis, I.; Kunrath, A.; Deutsch, T.; Kuritzky, L.; Miller, E.; Madan, A.

    2008-01-01

    We report the use of hydrogenated amorphous silicon carbide (a-SiC:H) prepared by plasma enhanced chemical vapor deposition (PECVD) as the photoelectrode in an integrated 'hybrid' photoelectrochemical (PEC) cell to produce hydrogen directly from water using sunlight. Results on the durability of hydrogenated amorphous silicon carbide (a-SiC:H) photoelectrodes in an electrolyte are presented. In a pH2 electrolyte, the a-SiC:H photoelectrode exhibits excellent stability for 100 hour test so far performed. A photocurrent onset shift (anodically) after a 24- or 100-hour durability test in electrolyte is observed, likely due to changes in the surface chemical structure of the a-SiC:H photoelectrode. It is also observed that a thin SiOx layer native to the air exposed surface of the a-SiC:H affects the photocurrent and the its onset shift. Finally, approaches for eliminating the external bias voltage and enhancing the solar-to-hydrogen efficiency in a PV/PEC hybrid structure to achieve {>=} 10% are presented.

  12. Status of research and development on photoelectrochemical hydrogen production in Korea

    NASA Astrophysics Data System (ADS)

    Kim, Jong Won; Lee, Jae S.; Baeg, Jin-Ook

    2010-08-01

    Conversion of solar energy into hydrogen is one of the most promising renewable energy technologies. Photocatalytic production of hydrogen from water, H2S and organic wastes using semiconductors is one of the potential strategies for converting the sunlight energy into chemical energy. Korea government paid great attention to the hydrogen economy and launched the HERC (Hydrogen Energy R&D Center) for supporting the R&D topics on hydrogen related technologies. The key issue for realizing the commercial application of solar water splitting hydrogen production technique is to find an efficient, stable and low-cost photocatalyst. Our research groups have continuously investigated to find oxide and composite photocatalysts for photoelectrochemical cell with high efficiency using computational design and synthesis method. But, fundamental research on semiconductor doping for band gap shifting and surface chemistry modification is still required. Various reaction media containing sacrificial agents should be developed to match with high activity photocatalysts to further improve the system efficiency. Water containing organic/inorganic waste and sea water are particularly suggested in the consideration that all these water sources are the most available water on the earth to the final commercial application of photocatalytic water splitting technique.

  13. A magnetic cell-based sensor.

    PubMed

    Wang, Hua; Mahdavi, Alborz; Tirrell, David A; Hajimiri, Ali

    2012-11-01

    Cell-based sensing represents a new paradigm for performing direct and accurate detection of cell- or tissue-specific responses by incorporating living cells or tissues as an integral part of a sensor. Here we report a new magnetic cell-based sensing platform by combining magnetic sensors implemented in the complementary metal-oxide-semiconductor (CMOS) integrated microelectronics process with cardiac progenitor cells that are differentiated directly on-chip. We show that the pulsatile movements of on-chip cardiac progenitor cells can be monitored in a real-time manner. Our work provides a new low-cost approach to enable high-throughput screening systems as used in drug development and hand-held devices for point-of-care (PoC) biomedical diagnostic applications.

  14. Mg-Zr Cosubstituted Ta3N5 Photoanode for Lower-Onset-Potential Solar-Driven Photoelectrochemical Water Splitting.

    PubMed

    Seo, Jeongsuk; Takata, Tsuyoshi; Nakabayashi, Mamiko; Hisatomi, Takashi; Shibata, Naoya; Minegishi, Tsutomu; Domen, Kazunari

    2015-10-14

    In p/n photoelectrochemical (PEC) cell systems, a low onset potential for the photoanode, as well as a high photocurrent, are critical for efficient water splitting. Here, we report a Mg-Zr cosubstituted Ta3N5 (Ta3N5:Mg+Zr) photoanode, designed to provide a more negative onset potential for PEC water splitting. The anodic photocurrent onset on Ta3N5:Mg+Zr was 0.55 V(RHE) under AM 1.5G-simulated sunlight, which represented a negative shift from the ca. 0.8 V(RHE) for pure Ta3N5. This negative shift in the onset potential of PEC water splitting was attributed to the change in the bandgap potential due to partial substitution by the foreign ions Mg(2+) and/or Zr(4+). PMID:26426439

  15. Photoelectrochemical detection of enzymatically generated CdS nanoparticles: Application to development of immunoassay.

    PubMed

    Barroso, Javier; Saa, Laura; Grinyte, Ruta; Pavlov, Valeri

    2016-03-15

    We report an innovative photoelectrochemical process (PEC) based on graphite electrode modified with electroactive polyvinylpyridine bearing osmium complex (Os-PVP). The system relies on the in situ enzymatic generation of CdS quantum dots (QDs). Alkaline phosphatase (ALP) catalyzes the hydrolisis of sodium thiophosphate (TP) to hydrogen sulfide (H2S) which in the presence Cd(2+) ions yields CdS semiconductor nanoparticles (SNPs). Irradiation of SNPs with the standard laboratory UV-illuminator (wavelength of 365 nm) results in photooxidation of 1-thioglycerol (TG) mediated by Os-PVP complex on the surface of graphite electrode at applied potential of 0.31 V vs. Ag/AgCl. A novel immunoassay based on specific enzyme linked immunosorbent assay (ELISA) combined with the PEC methodology was developed. Having selected the affinity interaction between bovine serum albumine (BSA) with anti-BSA antibody (AB) as a model system, we built the PEC immunoassay for AB. The new assay displays a linear range up to 20 ngmL(-1) and a detection limit (DL) of 2 ngmL(-1) (S/N=3) which is lower 5 times that of the traditional chromogenic ELISA test employing p-nitro-phenyl phosphate (pNPP). PMID:26432195

  16. Photoelectrochemical Behavior of Electrophoretically Deposited Hematite Thin Films Modified with Ti(IV).

    PubMed

    Dalle Carbonare, Nicola; Boaretto, Rita; Caramori, Stefano; Argazzi, Roberto; Dal Colle, Maurizio; Pasquini, Luca; Bertoncello, Renzo; Marelli, Marcello; Evangelisti, Claudio; Bignozzi, Carlo Alberto

    2016-01-01

    Doping hematite with different elements is a common strategy to improve the electrocatalytic activity towards the water oxidation reaction, although the exact effect of these external agents is not yet clearly understood. Using a feasible electrophoretic procedure, we prepared modified hematite films by introducing in the deposition solution Ti(IV) butoxide. Photoelectrochemical performances of all the modified electrodes were superior to the unmodified one, with a 4-fold increase in the photocurrent at 0.65 V vs. SCE in 0.1 M NaOH (pH 13.3) for the 5% Ti-modified electrode, which was the best performing electrode. Subsequent functionalization with an iron-based catalyst led, at the same potential, to a photocurrent of ca. 1.5 mA·cm(-2), one of the highest achieved with materials based on solution processing in the absence of precious elements. AFM, XPS, TEM and XANES analyses revealed the formation of different Ti(IV) oxide phases on the hematite surface, that can reduce surface state recombination and enhance hole injection through local surface field effects, as confirmed by electrochemical impedance analysis. PMID:27447604

  17. Upscaling of integrated photoelectrochemical water-splitting devices to large areas

    PubMed Central

    Turan, Bugra; Becker, Jan-Philipp; Urbain, Félix; Finger, Friedhelm; Rau, Uwe; Haas, Stefan

    2016-01-01

    Photoelectrochemical water splitting promises both sustainable energy generation and energy storage in the form of hydrogen. However, the realization of this vision requires laboratory experiments to be engineered into a large-scale technology. Up to now only few concepts for scalable devices have been proposed or realized. Here we introduce and realize a concept which, by design, is scalable to large areas and is compatible with multiple thin-film photovoltaic technologies. The scalability is achieved by continuous repetition of a base unit created by laser processing. The concept allows for independent optimization of photovoltaic and electrochemical part. We demonstrate a fully integrated, wireless device with stable and bias-free operation for 40 h. Furthermore, the concept is scaled to a device area of 64 cm2 comprising 13 base units exhibiting a solar-to-hydrogen efficiency of 3.9%. The concept and its successful realization may be an important contribution towards the large-scale application of artificial photosynthesis. PMID:27601181

  18. Upscaling of integrated photoelectrochemical water-splitting devices to large areas.

    PubMed

    Turan, Bugra; Becker, Jan-Philipp; Urbain, Félix; Finger, Friedhelm; Rau, Uwe; Haas, Stefan

    2016-01-01

    Photoelectrochemical water splitting promises both sustainable energy generation and energy storage in the form of hydrogen. However, the realization of this vision requires laboratory experiments to be engineered into a large-scale technology. Up to now only few concepts for scalable devices have been proposed or realized. Here we introduce and realize a concept which, by design, is scalable to large areas and is compatible with multiple thin-film photovoltaic technologies. The scalability is achieved by continuous repetition of a base unit created by laser processing. The concept allows for independent optimization of photovoltaic and electrochemical part. We demonstrate a fully integrated, wireless device with stable and bias-free operation for 40 h. Furthermore, the concept is scaled to a device area of 64 cm(2) comprising 13 base units exhibiting a solar-to-hydrogen efficiency of 3.9%. The concept and its successful realization may be an important contribution towards the large-scale application of artificial photosynthesis. PMID:27601181

  19. Photoelectrochemical detection of enzymatically generated CdS nanoparticles: Application to development of immunoassay.

    PubMed

    Barroso, Javier; Saa, Laura; Grinyte, Ruta; Pavlov, Valeri

    2016-03-15

    We report an innovative photoelectrochemical process (PEC) based on graphite electrode modified with electroactive polyvinylpyridine bearing osmium complex (Os-PVP). The system relies on the in situ enzymatic generation of CdS quantum dots (QDs). Alkaline phosphatase (ALP) catalyzes the hydrolisis of sodium thiophosphate (TP) to hydrogen sulfide (H2S) which in the presence Cd(2+) ions yields CdS semiconductor nanoparticles (SNPs). Irradiation of SNPs with the standard laboratory UV-illuminator (wavelength of 365 nm) results in photooxidation of 1-thioglycerol (TG) mediated by Os-PVP complex on the surface of graphite electrode at applied potential of 0.31 V vs. Ag/AgCl. A novel immunoassay based on specific enzyme linked immunosorbent assay (ELISA) combined with the PEC methodology was developed. Having selected the affinity interaction between bovine serum albumine (BSA) with anti-BSA antibody (AB) as a model system, we built the PEC immunoassay for AB. The new assay displays a linear range up to 20 ngmL(-1) and a detection limit (DL) of 2 ngmL(-1) (S/N=3) which is lower 5 times that of the traditional chromogenic ELISA test employing p-nitro-phenyl phosphate (pNPP).

  20. Upscaling of integrated photoelectrochemical water-splitting devices to large areas

    NASA Astrophysics Data System (ADS)

    Turan, Bugra; Becker, Jan-Philipp; Urbain, Félix; Finger, Friedhelm; Rau, Uwe; Haas, Stefan

    2016-09-01

    Photoelectrochemical water splitting promises both sustainable energy generation and energy storage in the form of hydrogen. However, the realization of this vision requires laboratory experiments to be engineered into a large-scale technology. Up to now only few concepts for scalable devices have been proposed or realized. Here we introduce and realize a concept which, by design, is scalable to large areas and is compatible with multiple thin-film photovoltaic technologies. The scalability is achieved by continuous repetition of a base unit created by laser processing. The concept allows for independent optimization of photovoltaic and electrochemical part. We demonstrate a fully integrated, wireless device with stable and bias-free operation for 40 h. Furthermore, the concept is scaled to a device area of 64 cm2 comprising 13 base units exhibiting a solar-to-hydrogen efficiency of 3.9%. The concept and its successful realization may be an important contribution towards the large-scale application of artificial photosynthesis.

  1. Graphene based enzymatic bioelectrodes and biofuel cells

    NASA Astrophysics Data System (ADS)

    Karimi, Anahita; Othman, Ali; Uzunoglu, Aytekin; Stanciu, Lia; Andreescu, Silvana

    2015-04-01

    The excellent electrical conductivity and ease of functionalization make graphene a promising material for use in enzymatic bioelectrodes and biofuel cells. Enzyme based biofuel cells have attracted substantial interest due to their potential to harvest energy from organic materials. This review provides an overview of the functional properties and applications of graphene in the construction of biofuel cells as alternative power sources. The review covers the current state-of-the-art research in graphene based nanomaterials (physicochemical properties and surface functionalities), the role of these parameters in enhancing electron transfer, the stability and activity of immobilized enzymes, and how enhanced power density can be achieved. Specific examples of enzyme immobilization methods, enzyme loading, stability and function on graphene, functionalized graphene and graphene based nanocomposite materials are discussed along with their advantages and limitations. Finally, a critical evaluation of the performance of graphene based enzymatic biofuel cells, the current status, challenges and future research needs are provided.

  2. Graphene based enzymatic bioelectrodes and biofuel cells.

    PubMed

    Karimi, Anahita; Othman, Ali; Uzunoglu, Aytekin; Stanciu, Lia; Andreescu, Silvana

    2015-04-28

    The excellent electrical conductivity and ease of functionalization make graphene a promising material for use in enzymatic bioelectrodes and biofuel cells. Enzyme based biofuel cells have attracted substantial interest due to their potential to harvest energy from organic materials. This review provides an overview of the functional properties and applications of graphene in the construction of biofuel cells as alternative power sources. The review covers the current state-of-the-art research in graphene based nanomaterials (physicochemical properties and surface functionalities), the role of these parameters in enhancing electron transfer, the stability and activity of immobilized enzymes, and how enhanced power density can be achieved. Specific examples of enzyme immobilization methods, enzyme loading, stability and function on graphene, functionalized graphene and graphene based nanocomposite materials are discussed along with their advantages and limitations. Finally, a critical evaluation of the performance of graphene based enzymatic biofuel cells, the current status, challenges and future research needs are provided. PMID:25832672

  3. Raman Spectroscopy Cell-based Biosensors

    PubMed Central

    Notingher, Ioan

    2007-01-01

    One of the main challenges faced by biodetection systems is the ability to detect and identify a large range of toxins at low concentrations and in short times. Cell-based biosensors rely on detecting changes in cell behaviour, metabolism, or induction of cell death following exposure of live cells to toxic agents. Raman spectroscopy is a powerful technique for studying cellular biochemistry. Different toxic chemicals have different effects on living cells and induce different time-dependent biochemical changes related to cell death mechanisms. Cellular changes start with membrane receptor signalling leading to cytoplasmic shrinkage and nuclear fragmentation. The potential advantage of Raman spectroscopy cell-based systems is that they are not engineered to respond specifically to a single toxic agent but are free to react to many biologically active compounds. Raman spectroscopy biosensors can also provide additional information from the time-dependent changes of cellular biochemistry. Since no cell labelling or staining is required, the specific time dependent biochemical changes in the living cells can be used for the identification and quantification of the toxic agents. Thus, detection of biochemical changes of cells by Raman spectroscopy could overcome the limitations of other biosensor techniques, with respect to detection and discrimination of a large range of toxic agents. Further developments of this technique may also include integration of cellular microarrays for high throughput in vitro toxicological testing of pharmaceuticals and in situ monitoring of the growth of engineered tissues.

  4. Cell-based strategies for vascular regeneration.

    PubMed

    Zou, Tongqiang; Fan, Jiabing; Fartash, Armita; Liu, Haifeng; Fan, Yubo

    2016-05-01

    Vascular regeneration is known to play an essential role in the repair of injured tissues mainly through accelerating the repair of vascular injury caused by vascular diseases, as well as the recovery of ischemic tissues. However, the clinical vascular regeneration is still challenging. Cell-based therapy is thought to be a promising strategy for vascular regeneration, since various cells have been identified to exert important influences on the process of vascular regeneration such as the enhanced endothelium formation on the surface of vascular grafts, and the induction of vessel-like network formation in the ischemic tissues. Here are a vast number of diverse cell-based strategies that have been extensively studied in vascular regeneration. These strategies can be further classified into three main categories, including cell transplantation, construction of tissue-engineered grafts, and surface modification of scaffolds. Cells used in these strategies mainly refer to terminally differentiated vascular cells, pluripotent stem cells, multipotent stem cells, and unipotent stem cells. The aim of this review is to summarize the reported research advances on the application of various cells for vascular regeneration, yielding insights into future clinical treatment for injured tissue/organ. PMID:26864677

  5. Cell-Based Therapy for Urinary Incontinence

    PubMed Central

    Bae, Jae Hyun

    2010-01-01

    Urinary incontinence has become a societal problem that affects millions of people worldwide. Although numerous therapeutic modalities are available, none has been shown to be entirely satisfactory. Consequently, cell-based approaches using regenerative medicine technology have emerged as a potential solution that would provide a means of correcting anatomical deficiencies and restoring normal function. As such, numerous cell-based investigations have been performed to develop systems that are focused on addressing clinical needs. While most of these attempts remain in the experimental stages, several clinical trials are being designed or are in progress. This article provides an overview of the cell-based approaches that utilize various cell sources to develop effective treatment modalities for urinary incontinence. PMID:20414402

  6. TiN-buffered substrates for photoelectrochemical measurements of oxynitride thin films

    NASA Astrophysics Data System (ADS)

    Pichler, Markus; Pergolesi, Daniele; Landsmann, Steve; Chawla, Vipin; Michler, Johann; Döbeli, Max; Wokaun, Alexander; Lippert, Thomas

    2016-04-01

    Developing novel materials for the conversion of solar to chemical energy is becoming an increasingly important endeavour. Perovskite compounds based on bandgap tunable oxynitrides represent an exciting class of novel photoactive materials. To date, literature mostly focuses on the characterization of oxynitride powder samples which have undeniable technological interest but do not allow the investigation of fundamental properties such as the role of the crystalline quality and/or the surface crystallographic orientation toward photo-catalytic activity. The challenge of growing high quality oxynitride thin films arises from the availability of a suitable substrate, owing to strict material and processing requirements: effective lattice matching, sufficiently high conductivities, stability under high temperatures and in strongly reducing environments. Here, we have established the foundations of a model system incorporating a TiN-buffer layer which enables fundamental investigations into crystallographic surface orientation and crystalline quality of the photocatalyst against photo(electro)chemical performance to be effectively performed. Furthermore, we find that TiN as current collector enables control over the nitrogen content of oxynitride thin films produced by a modified pulsed laser deposition method and allows the growth of highly ordered LaTiO3-xNx thin films.

  7. Cobalt-phosphate-assisted photoelectrochemical water oxidation by arrays of molybdenum-doped zinc oxide nanorods.

    PubMed

    Lin, Yan-Gu; Hsu, Yu-Kuei; Chen, Ying-Chu; Lee, Bing-Wei; Hwang, Jih-Shang; Chen, Li-Chyong; Chen, Kuei-Hsien

    2014-09-01

    We report the first demonstration of cobalt phosphate (Co-Pi)-assisted molybdenum-doped zinc oxide nanorods (Zn(1-x)Mo(x)O NRs) as visible-light-sensitive photofunctional electrodes to fundamentally improve the performance of ZnO NRs for photoelectrochemical (PEC) water splitting. A maximum photoconversion efficiency as high as 1.05% was achieved, at a photocurrent density of 1.4 mA cm(-2). More importantly, in addition to achieve the maximum incident photon to current conversion efficiency (IPCE) value of 86%, it could be noted that the IPCE of Zn(1-x)Mo(x)O photoanodes under monochromatic illumination (450 nm) is up to 12%. Our PEC performances are comparable to those of many oxide-based photoanodes in recent reports. The improvement in photoactivity of PEC water splitting may be attributed to the enhanced visible-light absorption, increased charge-carrier densities, and improved interfacial charge-transfer kinetics due to the combined effect of molybdenum incorporation and Co-Pi modification, contributing to photocatalysis. The new design of constructing highly photoactive Co-Pi-assisted Zn(1-x)Mo(x)O photoanodes enriches knowledge on doping and advances the development of high-efficiency photoelectrodes in the solar-hydrogen field.

  8. Interface induce growth of intermediate layer for bandgap engineering insights into photoelectrochemical water splitting

    PubMed Central

    Zhang, Jian; Zhang, Qiaoxia; Wang, Lianhui; Li, Xing’ao; Huang, Wei

    2016-01-01

    A model of interface induction for interlayer growing is proposed for bandgap engineering insights into photocatalysis. In the interface of CdS/ZnS core/shell nanorods, a lamellar solid solution intermediate with uniform thickness and high crystallinity was formed under interface induction process. Merged the novel charge carrier transfer layer, the photocurrent of the core/shell/shell nanorod (css-NR) array was significantly improved to 14.0 mA cm−2 at 0.0 V vs. SCE, nearly 8 times higher than that of the perfect CdS counterpart and incident photon to electron conversion efficiency (IPCE) values above 50% under AM 1.5G irradiation. In addition, this array photoelectrode showed excellent photocatalytic stability over 6000 s. These results suggest that the CdS/Zn1−xCdxS/ZnS css-NR array photoelectrode provides a scalable charge carrier transfer channel, as well as durability, and therefore is promising to be a large-area nanostructured CdS-based photoanodes in photoelectrochemical (PEC) water splitting system. PMID:27250648

  9. First-principles interpretation of core-level spectroscopy of photoelectrochemical materials and processes

    NASA Astrophysics Data System (ADS)

    Pemmaraju, Sri Chaitanya Das; Prendergast, David

    2014-03-01

    We present two case studies of first-principles theoretical methods applied in conjunction with experimental core-level spectroscopy measurements to investigate the electronic structure and dynamical processes in molecular and interfacial systems relevant to photoelectrochemical (PEC) technologies. In the first, we study the core-level and valence spectroscopies of two zinc(II)-porphyrin based Donor-pi-Acceptor (D-p-A) dyes using the occupancy-constrained excited electron and core-hole (XCH) approach and time-dependent density functional theory (TDDFT) simulations. In the second, we use constrained DFT and TDDFT to interpret measured transient core-level shifts in time-resolved femtosecond x-ray photoelectron spectroscopy, investigating the dynamics of the electron injection process from a N3 dye molecule chemisorbed onto a ZnO substrate. These studies illustrate the utility of first-principles methods in guiding the design of better PEC materials. This work was performed at the Molecular Foundry, LBNL, supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  10. A highly selective and picomolar level photoelectrochemical sensor for PCB 101 detection in environmental water samples.

    PubMed

    Shi, Huijie; Zhao, Jinzhi; Wang, Yingling; Zhao, Guohua

    2016-07-15

    A highly selective and sensitive photoelectrochemical (PEC) sensor was fabricated for fast and convenient detection of PCB 101 in environmental water samples with a low detection limit of 1.0×10(-14)molL(-1) based on single crystalline TiO2 nanorods (NRs). By integration with molecular imprinting (MI) technique, the PEC sensor's selectivity towards PCB 101 was significantly improved, so that the interference caused by 100-fold excess of PCB 126 and PCB 77 which had similar structure with PCB 101 was below 37%, not to mention other coexisted pollutants. This high selectivity could be attributed to the high-quality expression of the molecular imprinting sites on the rigid and smooth surface of single crystalline TiO2 NRs on which PCB 101 could be selectively and preferentially adsorbed. The oriented and multiple halogen bonds formed between PCB 101 and the molecular imprinting sites played a critical role in improving the recognition ability of the PEC sensor. Meanwhile, the one dimensional nanorods structure of TiO2 was beneficial for the efficient separation of photogenerated electrons and holes, leading to enhanced photocurrent response and further improving the sensitivity of the PEC sensor. PMID:27016911

  11. Graphitic carbon nitride/BiOCl composites for sensitive photoelectrochemical detection of ciprofloxacin.

    PubMed

    Xu, Li; Li, Henan; Yan, Pengcheng; Xia, Jiexiang; Qiu, Jingxia; Xu, Qian; Zhang, Shanqing; Li, Huaming; Yuan, Shouqi

    2016-12-01

    Ciprofloxacin, as a second generation of fluoroquinolone antibiotics, has been proved to cause environmental harm and exhibits toxic effects on the wastewater and surface water even at low concentrations due to their continuous input and persistence. Despite tremendous efforts, developing ciprofloxacin detection method with accuracy and sensitivity at low-cost remains a great challenge. Herein, graphitic carbon nitride/BiOCl composite (g-CN/BiOCl) has been designed for a facile and sensitive photoelectrochemical (PEC) monitoring platform of ciprofloxacin at first time. BiOCl can be modified with the g-CN nanosheets which are obtained via solvothermal process at low-temperature conditions. The use of g-CN is shown to strongly enhance the PEC response of BiOCl due to the formation of heterojunctions. The photocurrent generated at the g-CN/BiOCl-modified ITO (with 13wt%g-CN content) is much higher and more stable than that of a BiOCl-modified ITO. Based on these findings, the g-CN/BiOCl-modified ITO was used to design a PEC assay for the antibiotic ciprofloxacin. Furthermore, the limit of detection of the ciprofloxacin PEC sensor has been significantly lowered to 0.2ngmL(-1). In addition, the PEC sensor can detect ciprofloxacin in the wide range of 0.5-1840ngmL(-1). PMID:27552431

  12. Interface induce growth of intermediate layer for bandgap engineering insights into photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Zhang, Qiaoxia; Wang, Lianhui; Li, Xing’Ao; Huang, Wei

    2016-06-01

    A model of interface induction for interlayer growing is proposed for bandgap engineering insights into photocatalysis. In the interface of CdS/ZnS core/shell nanorods, a lamellar solid solution intermediate with uniform thickness and high crystallinity was formed under interface induction process. Merged the novel charge carrier transfer layer, the photocurrent of the core/shell/shell nanorod (css-NR) array was significantly improved to 14.0 mA cm‑2 at 0.0 V vs. SCE, nearly 8 times higher than that of the perfect CdS counterpart and incident photon to electron conversion efficiency (IPCE) values above 50% under AM 1.5G irradiation. In addition, this array photoelectrode showed excellent photocatalytic stability over 6000 s. These results suggest that the CdS/Zn1‑xCdxS/ZnS css-NR array photoelectrode provides a scalable charge carrier transfer channel, as well as durability, and therefore is promising to be a large-area nanostructured CdS-based photoanodes in photoelectrochemical (PEC) water splitting system.

  13. Interface induce growth of intermediate layer for bandgap engineering insights into photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Zhang, Qiaoxia; Wang, Lianhui; Li, Xing'Ao; Huang, Wei

    2016-06-01

    A model of interface induction for interlayer growing is proposed for bandgap engineering insights into photocatalysis. In the interface of CdS/ZnS core/shell nanorods, a lamellar solid solution intermediate with uniform thickness and high crystallinity was formed under interface induction process. Merged the novel charge carrier transfer layer, the photocurrent of the core/shell/shell nanorod (css-NR) array was significantly improved to 14.0 mA cm-2 at 0.0 V vs. SCE, nearly 8 times higher than that of the perfect CdS counterpart and incident photon to electron conversion efficiency (IPCE) values above 50% under AM 1.5G irradiation. In addition, this array photoelectrode showed excellent photocatalytic stability over 6000 s. These results suggest that the CdS/Zn1-xCdxS/ZnS css-NR array photoelectrode provides a scalable charge carrier transfer channel, as well as durability, and therefore is promising to be a large-area nanostructured CdS-based photoanodes in photoelectrochemical (PEC) water splitting system.

  14. Facet cutting and hydrogenation of In(2)O(3) nanowires for enhanced photoelectrochemical water splitting.

    PubMed

    Meng, Ming; Wu, Xinglong; Zhu, Xiaobin; Zhu, Xiaoshu; Chu, Paul K

    2014-03-26

    Semiconductor nanowires (NWs) are useful building blocks in optoelectronic, sensing, and energy devices and one-dimensional NWs have been used in photoelectrochemical (PEC) water splitting because of the enhanced light absorption and charge transport. It has been theoretically predicted that the {001} facets of body center cubic (bcc) In2O3 nanocrystals can effectively accumulate photogenerated holes under illumination, but it is unclear whether facet cutting of NWs can enhance the efficiency of PEC water splitting. In this work, the photocurrent of square In2O3 NWs with four {001} facets is observed to be an order of magnitude larger than that of cylindrical In2O3 NWs under the same conditions and subsequent hydrogen treatment further promotes the PEC water splitting performance of the NWs. The optimized hydrogenated In2O3 NWs yield a photocurrent density of 1.2 mA/cm(2) at 0.22 V versus Ag/AgCl with a Faradaic efficiency of about 84.4%. The enhanced PEC properties can be attributed to the reduced band gap due to merging of the disordered layer-induced band tail states with the valence band as well as improved separation of the photogenerated electrons/holes between the In2O3 crystal core and disordered layer interface. The results provide experimental evidence of the important role of facet cutting, which is promising in the design and fabrication of NW-based photoelectric devices. PMID:24568166

  15. Local electronic structure and photoelectrochemical activity of partial chemically etched Ti-doped hematite

    NASA Astrophysics Data System (ADS)

    Rioult, Maxime; Belkhou, Rachid; Magnan, Hélène; Stanescu, Dana; Stanescu, Stefan; Maccherozzi, Francesco; Rountree, Cindy; Barbier, Antoine

    2015-11-01

    The direct conversion of solar light into chemical energy or fuel through photoelectrochemical water splitting is promising as a clean hydrogen production solution. Ti-doped hematite (Ti:α-Fe2O3) is a potential key photoanode material, which despite its optimal band gap, excellent chemical stability, abundance, non-toxicity and low cost, still has to be improved. Here we give evidence of a drastic improvement of the water splitting performances of Ti-doped hematite photoanodes upon a HCl wet-etching. In addition to the topography investigation by atomic force microscopy, a detailed determination of the local electronic structure has been carried out in order to understand the phenomenon and to provide new insights in the understanding of solar water splitting. Using synchrotron radiation based spectromicroscopy (X-PEEM), we investigated the X-ray absorption spectral features at the L3 Fe edge of the as grown surface and of the wet-etched surface on the very same sample thanks to patterning. We show that HCl wet etching leads to substantial surface modifications of the oxide layer including increased roughness and chemical reduction (presence of Fe2 +) without changing the band gap. We demonstrate that these changes are profitable and correlated to the drastic changes of the photocatalytic activity.

  16. Graphitic carbon nitride/BiOCl composites for sensitive photoelectrochemical detection of ciprofloxacin.

    PubMed

    Xu, Li; Li, Henan; Yan, Pengcheng; Xia, Jiexiang; Qiu, Jingxia; Xu, Qian; Zhang, Shanqing; Li, Huaming; Yuan, Shouqi

    2016-12-01

    Ciprofloxacin, as a second generation of fluoroquinolone antibiotics, has been proved to cause environmental harm and exhibits toxic effects on the wastewater and surface water even at low concentrations due to their continuous input and persistence. Despite tremendous efforts, developing ciprofloxacin detection method with accuracy and sensitivity at low-cost remains a great challenge. Herein, graphitic carbon nitride/BiOCl composite (g-CN/BiOCl) has been designed for a facile and sensitive photoelectrochemical (PEC) monitoring platform of ciprofloxacin at first time. BiOCl can be modified with the g-CN nanosheets which are obtained via solvothermal process at low-temperature conditions. The use of g-CN is shown to strongly enhance the PEC response of BiOCl due to the formation of heterojunctions. The photocurrent generated at the g-CN/BiOCl-modified ITO (with 13wt%g-CN content) is much higher and more stable than that of a BiOCl-modified ITO. Based on these findings, the g-CN/BiOCl-modified ITO was used to design a PEC assay for the antibiotic ciprofloxacin. Furthermore, the limit of detection of the ciprofloxacin PEC sensor has been significantly lowered to 0.2ngmL(-1). In addition, the PEC sensor can detect ciprofloxacin in the wide range of 0.5-1840ngmL(-1).

  17. Cell-Based Genotoxicity Testing

    NASA Astrophysics Data System (ADS)

    Reifferscheid, Georg; Buchinger, Sebastian

    Genotoxicity test systems that are based on bacteria display an important role in the detection and assessment of DNA damaging chemicals. They belong to the basic line of test systems due to their easy realization, rapidness, broad applicability, high sensitivity and good reproducibility. Since the development of the Salmonella microsomal mutagenicity assay by Ames and coworkers in the early 1970s, significant development in bacterial genotoxicity assays was achieved and is still a subject matter of research. The basic principle of the mutagenicity assay is a reversion of a growth inhibited bacterial strain, e.g., due to auxotrophy, back to a fast growing phenotype (regain of prototrophy). Deeper knowledge of the ­mutation events allows a mechanistic understanding of the induced DNA-damage by the utilization of base specific tester strains. Collections of such specific tester strains were extended by genetic engineering. Beside the reversion assays, test systems utilizing the bacterial SOS-response were invented. These methods are based on the fusion of various SOS-responsive promoters with a broad variety of reporter genes facilitating numerous methods of signal detection. A very important aspect of genotoxicity testing is the bioactivation of ­xenobiotics to DNA-damaging compounds. Most widely used is the extracellular metabolic activation by making use of rodent liver homogenates. Again, genetic engineering allows the construction of highly sophisticated bacterial tester strains with significantly enhanced sensitivity due to overexpression of enzymes that are involved in the metabolism of xenobiotics. This provides mechanistic insights into the toxification and detoxification pathways of xenobiotics and helps explaining the chemical nature of hazardous substances in unknown mixtures. In summary, beginning with "natural" tester strains the rational design of bacteria led to highly specific and sensitive tools for a rapid, reliable and cost effective

  18. A cell nanoinjector based on carbon nanotubes

    SciTech Connect

    Chen, Xing; Kis, Andras; Zettl, Alex; Bertozzi, Carolyn R.

    2007-01-30

    Technologies for introducing molecules into living cells are vital for probing the physical properties and biochemical interactions that govern the cell's behavior. Here we report the development of a nanoscale cell injection system-termed the nanoinjector-that uses carbon nanotubes to deliver cargo into cells. A single multi-walled carbon nanotube attached to an atomic force microscope tip was functionalized with cargo via a disulfide-based linker. Penetration of cell membranes with this 'nanoneedle', followed by reductive cleavage of the disulfide bonds within the cell's interior, resulted in the release of cargo inside the cells. The capability of the nanoinjector was demonstrated by injection of protein-coated quantum dots into live human cells. Single-particle tracking was employed to characterize the diffusion dynamics of injected quantum dots in the cytosol. This new technique causes no discernible membrane or cell damage, and can deliver a discrete number of molecules to the cell's interior without the requirement of a carrier solvent.

  19. Enhanced photoelectrochemical activity of vertically aligned ZnO-coated TiO{sub 2} nanotubes

    SciTech Connect

    Cai, Hua; Yang, Qin; You, Qinghu; Sun, Jian; Xu, Ning; Wu, Jiada; Hu, Zhigao; Duan, Zhihua

    2014-02-03

    Vertically aligned ZnO-TiO{sub 2} hetero-nanostructures constructed of anatase TiO{sub 2} nanotubes (NTs) and wurtzite ZnO coatings are fabricated by atomic layer deposition of ZnO coatings on electrochemical anodization formed TiO{sub 2} NTs, and their photoelectrochemical activities are studied through photoelectrochemical and electrochemical characterization. Compared with bare TiO{sub 2} NTs, the transient photocurrent increases to over 1.5-fold for the annealed ZnO-coated TiO{sub 2} NTs under visible illumination. The ZnO-coated TiO{sub 2} NTs also show a longer electron lifetime, a lower charge-transfer resistance and a more negative flat-band potential than the bare TiO{sub 2} NTs, confirming the improved photoelectrochemical activity due to the enhanced charge separation.

  20. Oxidatively Stable Nanoporous Silicon Photocathodes for Photoelectrochemical Hydrogen Evolution

    SciTech Connect

    Neale, Nathan R.; Zhao, Yixin; Zhu, Kai; Oh, Jihun; van de Lagemaat, Jao; Yuan, Hao-Chih; Branz, Howard M.

    2014-06-02

    Stable and high-performance nanoporous 'black silicon' photoelectrodes with electrolessly deposited Pt nanoparticle (NP) catalysts are made with two metal-assisted etching steps. Doubly etched samples exhibit >20 mA/cm2 photocurrent density at +0.2 V vs. reversible hydrogen electrode (RHE) for photoelectrochemical hydrogen evolution under 1 sun illumination. We find that the photocurrent onset voltage of black Si photocathodes prepared from single-crystal planar Si wafers increases in oxidative environments (e.g., aqueous electrolyte) owing to a positive flat-band potential shift caused by surface oxidation. However, this beneficial oxide layer becomes a kinetic barrier to proton reduction that inhibits hydrogen production after just 24 h. To mitigate this problem, we developed a novel second Pt-assisted etch process that buries the Pt NPs deeper into the nanoporous Si surface. This second etch shifts the onset voltage positively, from +0.25 V to +0.4 V vs. RHE, and reduces the charge-transfer resistance with no performance decrease seen for at least two months.

  1. Solar Photoelectrochemical Energy Conversion using Earth-Abundant Nanomaterials

    NASA Astrophysics Data System (ADS)

    Lukowski, Mark A.

    Although the vast majority of energy consumed worldwide is derived from fossil fuels, the growing interest in making cleaner alternative energies more economically viable has motivated recent research efforts aimed to improve photovoltaic, wind, and biomass power generation. Clean power generation also requires clean burning fuels, such as H2 and O2, so that energy can still be provided on demand at all times, despite the intermittent nature inherent to solar or wind power. My research has focused on the rational approach to synthesizing earth-abundant nanomaterials with applications in the generation of clean alternative fuels and understanding the structure-property relationships which directly influence their performance. Herein, we describe the development of low-cost, earth-abundant layered metal chalcogenides as high-performance electrocatalysts for hydrogen evolution, and hematite photoanodes for photoelectrochemical oxygen evolution. This work has revealed a particularly interesting concept where catalytic performance can be enhanced by controlling the phase behavior of the material and taking advantage of previously unexploited properties to overcome the challenges traditionally limiting the performance of these layered materials for hydrogen evolution catalysis.

  2. Photovoltaic Characterization and Electrochemical Impedance Spectroscopy Analysis of Dye-Sensitized Solar Cells Based on Composite TiO2-MWCNT Photoelectrodes

    NASA Astrophysics Data System (ADS)

    Parvazian, E.; Karimzadeh, F.; Enayati, M. H.

    2014-05-01

    Dye-sensitized solar cells (DSSCs) use the effect of light on dye molecules to generate electricity through a photoelectrochemical mechanism. The aim of this study is to synthesize nanostructured DSSCs based on titania-multiwalled carbon nanotube (TiO2-MWCNT) composite photoelectrodes and improve their performance and efficiency. DSSCs were fabricated based on single-layer TiO2-MWCNT photoelectrodes with various weight percentages of multiwalled carbon nanotubes and bilayer TiO2/TiO2-2%MWCNT photoelectrodes. The microstructure and thickness of the anodic layers were characterized by field-emission scanning electron microscopy and optical microscopy. Also, to compare the conversion efficiency and determine the electron behavior in the electrical equivalent circuit of these cells, photovoltaic characterization and electrochemical impedance spectroscopy (EIS) analysis were used. The DSSC based on a single-layer TiO2-2%MWCNT electrode, compared with other single-layer DSSCs in this study, had the highest conversion efficiency of 3.9% (for anodic layer thickness of 9 μm). The efficiency of the solar cell with the bilayer TiO2/TiO2-2%MWCNT photoelectrode, in comparison with the single-layer solar cell with the TiO2-2%MWCNT electrode, showed a 23% increase from 4.33% to 5.35% (for anodic layer thickness of 18 μm). EIS analysis indicated that the charge-transport resistance of the DSSC based on the bilayer photoelectrode, in comparison with the single-layer TiO2 and TiO2-2%MWCNT solar cells, was decreased by 68% and 57%, respectively.

  3. Solid oxide MEMS-based fuel cells

    DOEpatents

    Jankowksi, Alan F.; Morse, Jeffrey D.

    2007-03-13

    A micro-electro-mechanical systems (MEMS) based thin-film fuel cells for electrical power applications. The MEMS-based fuel cell may be of a solid oxide type (SOFC), a solid polymer type (SPFC), or a proton exchange membrane type (PEMFC), and each fuel cell basically consists of an anode and a cathode separated by an electrolyte layer. The electrolyte layer can consist of either a solid oxide or solid polymer material, or proton exchange membrane electrolyte materials may be used. Additionally catalyst layers can also separate the electrodes (cathode and anode) from the electrolyte. Gas manifolds are utilized to transport the fuel and oxidant to each cell and provide a path for exhaust gases. The electrical current generated from each cell is drawn away with an interconnect and support structure integrated with the gas manifold. The fuel cells utilize integrated resistive heaters for efficient heating of the materials. By combining MEMS technology with thin-film deposition technology, thin-film fuel cells having microflow channels and full-integrated circuitry can be produced that will lower the operating temperature an will yield an order of magnitude greater power density than the currently known fuel cells.

  4. Solid polymer MEMS-based fuel cells

    DOEpatents

    Jankowski, Alan F.; Morse, Jeffrey D.

    2008-04-22

    A micro-electro-mechanical systems (MEMS) based thin-film fuel cells for electrical power applications. The MEMS-based fuel cell may be of a solid oxide type (SOFC), a solid polymer type (SPFC), or a proton exchange membrane type (PEMFC), and each fuel cell basically consists of an anode and a cathode separated by an electrolyte layer. The electrolyte layer can consist of either a solid oxide or solid polymer material, or proton exchange membrane electrolyte materials may be used. Additionally catalyst layers can also separate the electrodes (cathode and anode) from the electrolyte. Gas manifolds are utilized to transport the fuel and oxidant to each cell and provide a path for exhaust gases. The electrical current generated from each cell is drawn away with an interconnect and support structure integrated with the gas manifold. The fuel cells utilize integrated resistive heaters for efficient heating of the materials. By combining MEMS technology with thin-film deposition technology, thin-film fuel cells having microflow channels and full-integrated circuitry can be produced that will lower the operating temperature an will yield an order of magnitude greater power density than the currently known fuel cells.

  5. Mapping quantum yield for (Fe-Zn-Sn-Ti)Ox photoabsorbers using a high throughput photoelectrochemical screening system.

    PubMed

    Xiang, Chengxiang; Haber, Joel; Marcin, Martin; Mitrovic, Slobodan; Jin, Jian; Gregoire, John M

    2014-03-10

    Combinatorial synthesis and screening of light absorbers are critical to material discoveries for photovoltaic and photoelectrochemical applications. One of the most effective ways to evaluate the energy-conversion properties of a semiconducting light absorber is to form an asymmetric junction and investigate the photogeneration, transport and recombination processes at the semiconductor interface. This standard photoelectrochemical measurement is readily made on a semiconductor sample with a back-side metallic contact (working electrode) and front-side solution contact. In a typical combinatorial material library, each sample shares a common back contact, requiring novel instrumentation to provide spatially resolved and thus sample-resolved measurements. We developed a multiplexing counter electrode with a thin layer assembly, in which a rectifying semiconductor/liquid junction was formed and the short-circuit photocurrent was measured under chopped illumination for each sample in a material library. The multiplexing counter electrode assembly demonstrated a photocurrent sensitivity of sub-10 μA cm(-2) with an external quantum yield sensitivity of 0.5% for each semiconductor sample under a monochromatic ultraviolet illumination source. The combination of cell architecture and multiplexing allows high-throughput modes of operation, including both fast-serial and parallel measurements. To demonstrate the performance of the instrument, the external quantum yields of 1819 different compositions from a pseudoquaternary metal oxide library, (Fe-Zn-Sn-Ti)Ox, at 385 nm were collected in scanning serial mode with a throughput of as fast as 1 s per sample. Preliminary screening results identified a promising ternary composition region centered at Fe0.894Sn0.103Ti0.0034Ox, with an external quantum yield of 6.7% at 385 nm.

  6. Photoelectrochemical Properties of Vertically Aligned CuInS2 Nanorod Arrays Prepared via Template-Assisted Growth and Transfer.

    PubMed

    Yang, Wooseok; Oh, Yunjung; Kim, Jimin; Kim, Hyunchul; Shin, Hyunjung; Moon, Jooho

    2016-01-13

    Although copper-based chalcopyrite materials such as CuInS2 have been considered promising photocathodes for solar water splitting, the fabrication route for a nanostructure with vertical orientation has not yet been developed. Here, a fabrication route for vertically aligned CuInS2 nanorod arrays from an aqueous solution using anodic aluminum oxide template-assisted growth and transfer is presented. The nanorods exhibit a phase-pure CuInS2 chalcopyrite structure and cathodic photocurrent response without co-catalyst loading. Small particles of CdS and ZnS were conformally decorated onto CuInS2 nanorods using a successive ion layer adsorption and reaction method. With surface modification of CdS/ZnS, the photoelectrochemical properties of CuInS2 nanorod arrays are enhanced via flat-band potential shift, as determined by analyses of onset potential and Mott-Schottky plots. PMID:26645722

  7. Dual Influence of Reduction Annealing on Diffused Hematite/FTO Junction for Enhanced Photoelectrochemical Water Oxidation.

    PubMed

    Yang, Xiaogang; Liu, Rui; Lei, Yan; Li, Pinjiang; Wang, Ke; Zheng, Zhi; Wang, Dunwei

    2016-06-29

    Band structure engineering of the interface between the semiconductor and the conductive substrate may profoundly influence charge separation and transport for photovoltaic and photoelectrochemical devices. In this work, we found that a reduction-annealing treatment resulted in a diffused junction through enhanced interdiffusion of hematite/FTO at the interface. The activated hematite exhibited higher nanoelectric conductivity that was probed by a PeakForce TUNA AFM method. Furthermore, charge accumulation and recombination via surface states at the interface were dramatically reduced after the reduction-annealing activation, which was confirmed by transient surface photovoltage measurements. The diffused hematite junction promises improved photoelectrochemical performance without the need for a buffer layer.

  8. Possibilities of increased energetic use of photochemical, photoelectrochemical and biological methods of solar energy conversion

    NASA Astrophysics Data System (ADS)

    Hamer, E.; Moehwald, H.; Obkircher, B.; Schaefer, W.; Schroeder, B.

    1983-03-01

    Methods of photochemical, photoelectrochemical and biological solar energy conversion were elaborated for economical use in a far future. Present status and possibilities of development; physical and technical limitations; and cost of use in possible applications are discussed. The most promising method is the photoelectrochemical generation of electricity. Cases in which the production of biomass and the production of methanol by solar energy are feasible are outlined. The other methods, including those producing hydrogen by means of sunlight, cannot be used economically in regions of temperate climate.

  9. Cell-based therapy in allergy.

    PubMed

    Baranyi, Ulrike; Gattringer, Martina; Valenta, Rudolf; Wekerle, Thomas

    2011-01-01

    IgE-mediated allergy is an immunological disorder occurring in response to otherwise harmless environmental antigens (i.e., allergens). Development of effective therapeutic or preventive approaches inducing robust tolerance toward allergens remains an unmet goal. Several experimental tolerance approaches have been described. The therapeutic use of regulatory T cells (Tregs) and the establishment of molecular chimerism are two cell-based strategies that are of particular interest. Treg therapy is close to clinical application, but its efficacy remains to be fully defined. Recent proof-of-concept studies demonstrated that transplantation of syngeneic hematopoietic stem cells modified in vitro to express a major allergen leads to molecular chimerism and robust allergen-specific tolerance. Here we review cell-based tolerance strategies in allergy, discussing their potentials and limitations.

  10. Cell-based bioassays in microfluidic systems

    NASA Astrophysics Data System (ADS)

    Itle, Laura J.; Zguris, Jeanna C.; Pishko, Michael V.

    2004-12-01

    The development of cell-based bioassays for high throughput drug screening or the sensing of biotoxins is contingent on the development of whole cell sensors for specific changes in intracellular conditions and the integration of those systems into sample delivery devices. Here we show the feasibility of using a 5-(and-6)-carboxy SNARF-1, acetoxymethyl ester, acetate, a fluorescent dye capable of responding to changes in intracellular pH, as a detection method for the bacterial endotoxin, lipopolysaccharide. We used photolithography to entrap cells with this dye within poly(ethylene) glyocol diacrylate hydrogels in microfluidic channels. After 18 hours of exposure to lipopolysaccharide, we were able to see visible changes in the fluorescent pattern. This work shows the feasibility of using whole cell based biosensors within microfluidic networks to detect cellular changes in response to exogenous agents.

  11. Nanowire-based All Oxide Solar Cells

    SciTech Connect

    Yang*, Benjamin D. Yuhas and Peidong; Yang, Peidong

    2008-12-07

    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale photovoltaic devices. We found that the solar cell performance is enhanced with the addition of an intermediate oxide insulating layer between the nanowires and the nanoparticles. This observation of the important dependence of the shunt resistance on the photovoltaic performance is widely applicable to any nanowire solar cell constructed with the nanowire array in direct contact with one electrode.

  12. LTCC based bioreactors for cell cultivation

    NASA Astrophysics Data System (ADS)

    Bartsch, H.; Welker, T.; Welker, K.; Witte, H.; Müller, J.

    2016-01-01

    LTCC multilayers offer a wide range of structural options and flexibility of connections not available in standard thin film technology. Therefore they are considered as material base for cell culture reactors. The integration of microfluidic handling systems and features for optical and electrical capturing of indicators for cell culture growth offers the platform for an open system concept. The present paper assesses different approaches for the creation of microfluidic channels in LTCC multilayers. Basic functions required for the fluid management in bioreactors include temperature and flow control. Both features can be realized with integrated heaters and temperature sensors in LTCC multilayers. Technological conditions for the integration of such elements into bioreactors are analysed. The temperature regulation for the system makes use of NTC thermistor sensors which serve as real value input for the control of the heater. It allows the adjustment of the fluid temperature with an accuracy of 0.2 K. The tempered fluid flows through the cell culture chamber. Inside of this chamber a thick film electrode array monitors the impedance as an indicator for the growth process of 3-dimensional cell cultures. At the system output a flow sensor is arranged to monitor the continual flow. For this purpose a calorimetric sensor is implemented, and its crucial design parameters are discussed. Thus, the work presented gives an overview on the current status of LTCC based fluid management for cell culture reactors, which provides a promising base for the automation of cell culture processes.

  13. Sensitive-cell-based fish chromatophore biosensor

    NASA Astrophysics Data System (ADS)

    Plant, Thomas K.; Chaplen, Frank W.; Jovanovic, Goran; Kolodziej, Wojtek; Trempy, Janine E.; Willard, Corwin; Liburdy, James A.; Pence, Deborah V.; Paul, Brian K.

    2004-07-01

    A sensitive biosensor (cytosensor) has been developed based on color changes in the toxin-sensitive colored living cells of fish. These chromatophores are highly sensitive to the presence of many known and unknown toxins produced by microbial pathogens and undergo visible color changes in a dose-dependent manner. The chromatophores are immobilized and maintained in a viable state while potential pathogens multiply and fish cell-microbe interactions are monitored. Low power LED lighting is used to illuminate the chromatophores which are magnified using standard optical lenses and imaged onto a CCD array. Reaction to toxins is detected by observing changes is the total area of color in the cells. These fish chromatophores are quite sensitive to cholera toxin, Staphococcus alpha toxin, and Bordatella pertussis toxin. Numerous other toxic chemical and biological agents besides bacterial toxins also cause readily detectable color effects in chromatophores. The ability of the chromatophore cell-based biosensor to distinguish between different bacterial pathogens was examined. Toxin producing strains of Salmonella enteritis, Vibrio parahaemolyticus, and Bacillus cereus induced movement of pigmented organelles in the chromatophore cells and this movement was measured by changes in the optical density over time. Each bacterial pathogen elicited this measurable response in a distinctive and signature fashion. These results suggest a chromatophore cell-based biosensor assay may be applicable for the detection and identification of virulence activities associated with certain air-, food-, and water-borne bacterial pathogens.

  14. Biotoxin Detection Using Cell-Based Sensors

    PubMed Central

    Banerjee, Pratik; Kintzios, Spyridon; Prabhakarpandian, Balabhaskar

    2013-01-01

    Cell-based biosensors (CBBs) utilize the principles of cell-based assays (CBAs) by employing living cells for detection of different analytes from environment, food, clinical, or other sources. For toxin detection, CBBs are emerging as unique alternatives to other analytical methods. The main advantage of using CBBs for probing biotoxins and toxic agents is that CBBs respond to the toxic exposures in the manner related to actual physiologic responses of the vulnerable subjects. The results obtained from CBBs are based on the toxin-cell interactions, and therefore, reveal functional information (such as mode of action, toxic potency, bioavailability, target tissue or organ, etc.) about the toxin. CBBs incorporate both prokaryotic (bacteria) and eukaryotic (yeast, invertebrate and vertebrate) cells. To create CBB devices, living cells are directly integrated onto the biosensor platform. The sensors report the cellular responses upon exposures to toxins and the resulting cellular signals are transduced by secondary transducers generating optical or electrical signals outputs followed by appropriate read-outs. Examples of the layout and operation of cellular biosensors for detection of selected biotoxins are summarized. PMID:24335754

  15. Dye-Sensitized and Localized Surface Plasmon Resonance Enhanced Visible-Light Photoelectrochemical Biosensors for Highly Sensitive Analysis of Protein Kinase Activity.

    PubMed

    Yan, Zhiyong; Wang, Zonghua; Miao, Zhuang; Liu, Yang

    2016-01-01

    A novel visible-light photoelectrochemical (PEC) biosensor based on localized surface plasmon resonance (LSPR) enhancement and dye sensitization was fabricated for highly sensitive analysis of protein kinase activity with ultralow background. In this strategy, DNA conjugated gold nanoparticles (DNA@AuNPs) were assembled on the phosphorylated kemptide modified TiO2/ITO electrode through the chelation between Zr(4+) ions and phosphate groups, then followed by the intercalation of [Ru(bpy)3](2+) into DNA grooves. The adsorbed [Ru(bpy)3](2+) can harvest visible light to produce excited electrons that inject into the TiO2 conduction band to form photocurrent under visible light irradiation. In addition, the photocurrent efficiency was further improved by the LSPR of AuNPs under the irradiation of visible light. Moreover, because of the excellent conductivity and large surface area of AuNPs that facilitate electron-transfer and accommodate large number of [Ru(bpy)3](2+), the photocurrent was significantly amplified, affording an extremely sensitive PEC analysis of kinase activity with ultralow background signals. The detection limit of as-proposed PEC biosensor was 0.005 U mL(-1) (S/N = 3). The biosensor also showed excellent performances for quantitative kinase inhibitor screening and PKA activities detection in MCF-7 cell lysates under forskolin and ellagic acid stimulation. The developed dye-sensitization and LSPR enhancement visible-light PEC biosensor shows great potential in protein kinases-related clinical diagnosis and drug discovery. PMID:26648204

  16. Nanopillar based electrochemical biosensor for monitoring microfluidic based cell culture

    NASA Astrophysics Data System (ADS)

    Gangadharan, Rajan

    In-vitro assays using cultured cells have been widely performed for studying many aspects of cell biology and cell physiology. These assays also form the basis of cell based sensing. Presently, analysis procedures on cell cultures are done using techniques that are not integrated with the cell culture system. This approach makes continuous and real-time in-vitro measurements difficult. It is well known that the availability of continuous online measurements for extended periods of time will help provide a better understanding and will give better insight into cell physiological events. With this motivation we developed a highly sensitive, selective and stable microfluidic electrochemical glucose biosensor to make continuous glucose measurements in cell culture media. The performance of the microfluidic biosensor was enhanced by adding 3D nanopillars to the electrode surfaces. The microfluidic glucose biosensor consisted of three electrodes---Enzyme electrode, Working electrode, and Counter electrode. All these electrodes were enhanced with nanopillars and were optimized in their respective own ways to obtain an effective and stable biosensing device in cell culture media. For example, the 'Enzyme electrode' was optimized for enzyme immobilization via either a polypyrrole-based or a self-assembled-monolayer-based immobilization method, and the 'Working electrode' was modified with Prussian Blue or electropolymerized Neutral Red to reduce the working potential and also the interference from other interacting electro-active species. The complete microfluidic biosensor was tested for its ability to monitor glucose concentration changes in cell culture media. The significance of this work is multifold. First, the developed device may find applications in continuous and real-time measurements of glucose concentrations in in-vitro cell cultures. Second, the development of a microfluidic biosensor will bring technical know-how toward constructing continuous glucose

  17. Status of photoelectrochemical production of hydrogen and electrical energy

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Walker, G. H.

    1976-01-01

    The efficiency for conversion of electromagnetic energy to chemical and electrical energy utilizing semiconductor single crystals as photoanodes in electrochemical cells was investigated. Efficiencies as high as 20 percent were achieved for the conversion of 330 nm radiation to chemical energy in the form of hydrogen by the photoelectrolysis of water in a SrTiO3 based cell. The SrTiO3 photoanodes were shown to be stable in 9.5 M NaOH solutions for periods up to 48 hours. Efficiencies of 9 percent were measured for the conversion of broadband visible radiation to hydrogen using n-type GaAs crystals as photoanodes. Crystals of GaAs coated with 500 nm of gold, silver, or tin for surface passivation show no significant change in efficiency. By suppressing the production of hydrogen in a CdSe-based photogalvanic cell, an efficiency of 9 percent was obtained in conversion of 633 nm light to electrical energy. A CdS-based photogalvanic cell produced a conversion efficiency of 5 percent for 500 nm radiation.

  18. Earth-abundant oxygen evolution catalysts coupled onto ZnO nanowire arrays for efficient photoelectrochemical water cleavage.

    PubMed

    Jiang, Chaoran; Moniz, Savio J A; Khraisheh, Majeda; Tang, Junwang

    2014-09-26

    ZnO has long been considered as a model UV-driven photoanode for photoelectrochemical water splitting, but its performance has been limited by fast charge-carrier recombination, extremely poor stability in aqueous solution, and slow kinetics of water oxidation. These issues were addressed by applying a strategy of optimization and passivation of hydrothermally grown 1D ZnO nanowire arrays. The length and diameter of bare ZnO nanowires were optimized by varying the growth time and precursor concentration to achieve optimal photoelectrochemical performance. The addition of earth-abundant cobalt phosphate (Co-Pi) and nickel borate (Ni-B) oxygen evolution catalysts onto ZnO nanowires resulted in substantial cathodic shifts in onset potential to as low as about 0.3 V versus the reversible hydrogen electrode (RHE) for Ni-B/ZnO, for which a maximum photocurrent density of 1.1 mA cm(-2) at 0.9 V (vs. RHE) with applied bias photon-to-current efficiency of 0.4 % and an unprecedented near-unity incident photon-to-current efficiency at 370 nm. In addition the potential required for saturated photocurrent was dramatically reduced from 1.6 to 0.9 V versus RHE. Furthermore, the stability of these ZnO nanowires was significantly enhanced by using Ni-B compared to Co-Pi due to its superior chemical robustness, and it thus has additional functionality as a stable protecting layer on the ZnO surface. These remarkable enhancements in both photocatalytic activity and stability directly address the current severe limitations in the use of ZnO-based photoelectrodes for water-splitting applications, and can be applied to other photoanodes for efficient solar-driven fuel synthesis.

  19. Atomic Force Microscopy Based Cell Shape Index

    NASA Astrophysics Data System (ADS)

    Adia-Nimuwa, Usienemfon; Mujdat Tiryaki, Volkan; Hartz, Steven; Xie, Kan; Ayres, Virginia

    2013-03-01

    Stellation is a measure of cell physiology and pathology for several cell groups including neural, liver and pancreatic cells. In the present work, we compare the results of a conventional two-dimensional shape index study of both atomic force microscopy (AFM) and fluorescent microscopy images with the results obtained using a new three-dimensional AFM-based shape index similar to sphericity index. The stellation of astrocytes is investigated on nanofibrillar scaffolds composed of electrospun polyamide nanofibers that has demonstrated promise for central nervous system (CNS) repair. Recent work by our group has given us the ability to clearly segment the cells from nanofibrillar scaffolds in AFM images. The clear-featured AFM images indicated that the astrocyte processes were longer than previously identified at 24h. It was furthermore shown that cell spreading could vary significantly as a function of environmental parameters, and that AFM images could record these variations. The new three-dimensional AFM-based shape index incorporates the new information: longer stellate processes and cell spreading. The support of NSF PHY-095776 is acknowledged.

  20. Sn-doped hematite nanostructures for photoelectrochemical water splitting.

    PubMed

    Ling, Yichuan; Wang, Gongming; Wheeler, Damon A; Zhang, Jin Z; Li, Yat

    2011-05-11

    We report on the synthesis and characterization of Sn-doped hematite nanowires and nanocorals as well as their implementation as photoanodes for photoelectrochemical water splitting. The hematite nanowires were prepared on a fluorine-doped tin oxide (FTO) substrate by a hydrothermal method, followed by high temperature sintering in air to incorporate Sn, diffused from the FTO substrate, as a dopant. Sn-doped hematite nanocorals were prepared by the same method, by adding tin(IV) chloride as the Sn precursor. X-ray photoelectron spectroscopy analysis confirms Sn(4+) substitution at Fe(3+) sites in hematite, and Sn-dopant levels increase with sintering temperature. Sn dopant serves as an electron donor and increases the carrier density of hematite nanostructures. The hematite nanowires sintered at 800 °C yielded a pronounced photocurrent density of 1.24 mA/cm(2) at 1.23 V vs RHE, which is the highest value observed for hematite nanowires. In comparison to nanowires, Sn-doped hematite nanocorals exhibit smaller feature sizes and increased surface areas. Significantly, they showed a remarkable photocurrent density of 1.86 mA/cm(2) at 1.23 V vs RHE, which is approximately 1.5 times higher than that of the nanowires. Ultrafast spectroscopy studies revealed that there is significant electron-hole recombination within the first few picoseconds, while Sn doping and the change of surface morphology have no major effect on the ultrafast dynamics of the charge carriers on the picosecond time scales. The enhanced photoactivity in Sn-doped hematite nanostructures should be due to the improved electrical conductivity and increased surface area. PMID:21476581

  1. Novel Fuel Cells for Coal Based Systems

    SciTech Connect

    Thomas Tao

    2011-12-31

    The goal of this project was to acquire experimental data required to assess the feasibility of a Direct Coal power plant based upon an Electrochemical Looping (ECL) of Liquid Tin Anode Solid Oxide Fuel Cell (LTA-SOFC). The objective of Phase 1 was to experimentally characterize the interaction between the tin anode, coal fuel and cell component electrolyte, the fate of coal contaminants in a molten tin reactor (via chemistry) and their impact upon the YSZ electrolyte (via electrochemistry). The results of this work will provided the basis for further study in Phase 2. The objective of Phase 2 was to extend the study of coal impurities impact on fuel cell components other than electrolyte, more specifically to the anode current collector which is made of an electrically conducting ceramic jacket and broad based coal tin reduction. This work provided a basic proof-of-concept feasibility demonstration of the direct coal concept.

  2. Spatioselective Electrochemical and Photoelectrochemical Functionalization of Silicon Microwires with Axial p/n Junctions.

    PubMed

    Milbrat, Alexander; Elbersen, Rick; Kas, Recep; Tiggelaar, Roald M; Gardeniers, Han; Mul, Guido; Huskens, Jurriaan

    2016-02-17

    The spatioselective functionalization of silicon microwires with axial p/n junctions is achieved using the electronic properties of the junction. (Photo)electrochemical deposition of metals is demonstrated at the bottom and top of the wires in the dark and light, respectively. The junction depletion layer remains unmodified, which allows its visualization and comparison with theoretical calculations. PMID:26866621

  3. Charge Separation in TiO2/BDD Heterojunction Thin Film for Enhanced Photoelectrochemical Performance.

    PubMed

    Terashima, Chiaki; Hishinuma, Ryota; Roy, Nitish; Sugiyama, Yuki; Latthe, Sanjay S; Nakata, Kazuya; Kondo, Takeshi; Yuasa, Makoto; Fujishima, Akira

    2016-01-27

    Semiconductor photocatalysis driven by electron/hole has begun a new era in the field of solar energy conversion and storage. Here we report the fabrication and optimization of TiO2/BDD p-n heterojunction photoelectrode using p-type boron doped diamond (BDD) and n-type TiO2 which shows enhanced photoelectrochemical activity. A p-type BDD was first deposited on Si substrate by microwave plasma chemical vapor deposition (MPCVD) method and then n-type TiO2 was sputter coated on top of BDD grains for different durations. The microstructural studies reveal a uniform disposition of anatase TiO2 and its thickness can be tuned by varying the sputtering time. The formation of p-n heterojunction was confirmed through I-V measurement. A remarkable rectification property of 63773 at 5 V with very small leakage current indicates achieving a superior, uniform and precise p-n junction at TiO2 sputtering time of 90 min. This suitably formed p-n heterojunction electrode is found to show 1.6 fold higher photoelectrochemical activity than bare n-type TiO2 electrode at an applied potential of +1.5 V vs SHE. The enhanced photoelectrochemical performance of this TiO2/BDD electrode is ascribed to the injection of hole from p-type BDD to n-type TiO2, which increases carrier separation and thereby enhances the photoelectrochemical performance. PMID:26756353

  4. Electrospinning Nanofiber Based Organic Solar Cell

    NASA Astrophysics Data System (ADS)

    Yang, Zhenhua; Liu, Ying; Moffa, Maria; Nam, Chang-Yong; Pisignano, Dario; Rafailovich, Miriam

    Bulk heterojunction (BHJ) polymer solar cells are an area of intense interest due to their potential to result in printable, inexpensive solar cells which can be processed onto flexible substrates. The active layer is typically spin coated from the solution of polythiophene derivatives (donor) and fullerenes (acceptor) and interconnected domains are formed because of phase separation. However, the power conversion efficiency (PCE) of BHJ solar cell is restricted by the presence of unfavorable morphological features, including dead ends or isolated domains. Here we MEH-PPV:PVP:PCBM electrospun nanofiber into BHJ solar cell for the active layer morphology optimization. Larger interfacial area between donor and acceptor is abtained with electrospinning method and the high aspect ratio of the MEH-PPV:PVP:PCBM nanofibers allow them to easily form a continuous pathway. The surface morphology is investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrospun nanofibers are discussed as a favorable structure for application in bulk-heterojunction organic solar cells. Electrospinning Nanofiber Based Bulk Heterojunction Organic Solar Cell.

  5. III-Nitride Blue Laser Diode with Photoelectrochemically Etched Current Aperture

    NASA Astrophysics Data System (ADS)

    Megalini, Ludovico

    Group III-nitride is a remarkable material system to make highly efficient and high-power optoelectronics and electronic devices because of the unique electrical, physical, chemical and structural properties it offers. In particular, InGaN-based blue Laser Diodes (LDs) have been successfully employed in a variety of applications ranging from biomedical and military devices to scientific instrumentation and consumer electronics. Recently their use in highly efficient Solid State Lighting (SSL) has been proposed because of their superior beam quality and higher efficiency at high input power density. Tremendous advances in research of GaN semi-polar and non-polar crystallographic planes have led both LEDs and LDs grown on these non-basal planes to rival with, and with the promise to outperform, their equivalent c-plane counterparts. However, still many issues need to be addressed, both related to material growth and device fabrication, including a lack of conventional wet etching techniques. GaN and its alloys with InN and AlN have proven resistant essentially to all known standard wet etching techniques, and the predominant etching methods rely on chlorine-based dry etching (RIE). These introduce sub-surface damage which can degrade the electrical properties of the epitaxial structure and reduce the reliability and lifetime of the final device. Such reasons and the limited effectiveness of passivation techniques have so far suggested to etch the LD ridges before the active region, although it is well-known that this can badly affect the device performance, especially in narrow stripe width LDs, because the gain guiding obtained in the planar configuration is weak and the low index step and high lateral current leakage result in devices with threshold current density higher than devices whose ridge is etched beyond the active region. Moreover, undercut etching of III-nitride layers has proven even more challenging, with limitations in control of the lateral etch

  6. Preparation and properties of Sb[sub 2]S[sub 3] thin films for photoelectrochemical applications

    SciTech Connect

    Deshmukh, L.P.; Rane, B.P.; More, B.M.; Hankare, P.P. . Dept. of Physics); Holikatti, S.G. )

    1994-07-01

    A modified chemical deposition process has been employed for the preparation of antimony trisulfide thin layers onto the plane glass and stainless steel substrates. The as-deposited samples on baking at 120 C are orange-red in color and turn into the dark gray variety on heating to 200 C in an air ambient. The surface topography shows the polycrystalline nature of the samples. This is supported by x-ray diffraction observations. The deposits are of n-type with an electron activation energy of 0.80 eV. A n-Sb[sub 2]S[sub 3]/ferrocene-DMSO/C, photoelectrochemical cell was then devised and has been characterized in dark and in light in terms of electrical and optical properties. A short-circuit current (I[sub sc]) of 0.14 mA/cm[sup 2] and an open-circuit voltage (V[sub oc]) equal to 0.155 V are obtained form this cell configuration. The calculated efficiency approached to 0.008%. The other cell parameters have been determined from these studies.

  7. Synthesis of chemicals using solar energy with stable photoelectrochemically active heterostructures.

    PubMed

    Mubeen, Syed; Singh, Nirala; Lee, Joun; Stucky, Galen D; Moskovits, Martin; McFarland, Eric W

    2013-05-01

    Efficient and cost-effective conversion of solar energy to useful chemicals and fuels could lead to a significant reduction in fossil hydrocarbon use. Artificial systems that use solar energy to produce chemicals have been reported for more than a century. However the most efficient devices demonstrated, based on traditionally fabricated compound semiconductors, have extremely short working lifetimes due to photocorrosion by the electrolyte. Here we report a stable, scalable design and molecular level fabrication strategy to create photoelectrochemically active heterostructure (PAH) units consisting of an efficient semiconductor light absorber in contact with oxidation and reduction electrocatalysts and otherwise protected by alumina. The functional heterostructures are fabricated by layer-by-layer, template-directed, electrochemical synthesis in porous anodic aluminum oxide membranes to produce high density arrays of electronically autonomous, nanostructured, corrosion resistant, photoactive units (~10(9)-10(10) PAHs per cm(2)). Each PAH unit is isolated from its neighbor by the transparent electrically insulating oxide cellular enclosure that makes the overall assembly fault tolerant. When illuminated with visible light, the free floating devices have been demonstrated to produce hydrogen at a stable rate for over 24 h in corrosive hydroiodic acid electrolyte with light as the only input. The quantum efficiency (averaged over the solar spectrum) for absorbed photons-to-hydrogen conversion was 7.4% and solar-to-hydrogen energy efficiency of incident light was 0.9%. The fabrication approach is scalable for commercial manufacturing and readily adaptable to a variety of earth abundant semiconductors which might otherwise be unstable as photoelectrocatalysts.

  8. Polyaniline hybridized surface defective ZnO nanorods with long-term stable photoelectrochemical activity

    NASA Astrophysics Data System (ADS)

    Bera, Susanta; Khan, Hasmat; Biswas, Indranil; Jana, Sunirmal

    2016-10-01

    We report surfactant/template free precursor solution based synthesis of polyaniline (PANI) hybridized surface defective ZnO nanorods by a two-step process. Initially, ZnO nanorods have been prepared at 95 °C, followed by hybridization (coating) of PANI onto the ZnO via in situ polymerization of aniline monomer, forming ZnO-PANI nanohybrid (ZP). The structural properties of ZP have been analyzed by X-ray diffraction (XRD) and transmission electron microscopic (TEM) studies. The presence of surface defects especially the oxygen vacancies in ZnO has been characterized by photoluminescence emission, high resolution TEM, X-ray photoelectron spectroscopy (XPS) and micro-Raman spectral measurements. The chemical interaction of PANI with ZnO has been examined by Fourier transform infrared (FTIR) and XPS analyses. A significant enhancement in visible absorption of ZP sample is found as evidenced from UV-vis diffused reflectance spectral study. BET nitrogen adsorption-desorption isotherm shows an improved textural property (pore size, pore volume) of ZP. Moreover, a long-term stable photoelectrochemical activity (PEC) of ZP is found compare to pristine ZnO. The synergic effect of PANI hybridization and the presence of surface defects in ZnO NRs can enhance the PEC by prolonging the recombination rate of photogenerated charge carriers. The effect can also provide large number of active sites to make electrolyte diffusion and mass transportation easier in the nanohybrid. This simple synthesis strategy can be adopted for PANI hybridization with different metal oxide semiconductors towards enhancing PEC activity of the hybrid materials.

  9. Photoelectrochemical Conversion from Graphitic C3N4 Quantum Dot Decorated Semiconductor Nanowires.

    PubMed

    An, Tiance; Tang, Jing; Zhang, Yueyu; Quan, Yingzhou; Gong, Xingao; Al-Enizi, Abdullah M; Elzatahry, Ahmed A; Zhang, Lijuan; Zheng, Gengfeng

    2016-05-25

    Despite the recent progress of developing graphitic carbon nitride (g-C3N4) as a metal-free photocatalyst, the synthesis of nanostructured g-C3N4 has still remained a complicated and time-consuming approach from its bulk powder, which substantially limits its photoelectrochemical (PEC) applications as well as the potential to form composites with other semiconductors. Different from the labor-intensive methods used before, such as exfoliation or assistant templates, herein, we developed a facile method to synthesize graphitic C3N4 quantum dots (g-CNQDs) directly grown on TiO2 nanowire arrays via a one-step quasi-chemical vapor deposition (CVD) process in a homemade system. The as-synthesized g-CNQDs uniformly covered over the surface of TiO2 nanowires and exhibited attractive photoluminescence (PL) properties. In addition, compared to pristine TiO2, the heterojunction of g-CNQD-decorated TiO2 nanowires showed a substantially enhanced PEC photocurrent density of 3.40 mA/cm(2) at 0 V of applied potential vs Ag/AgCl under simulated solar light (300 mW/cm(2)) and excellent stability with ∼82% of the photocurrent retained after over 10 h of continuous testing, attributed to the quantum and sensitization effects of g-CNQDs. Density functional theory calculations were further carried out to illustrate the synergistic effect of TiO2 and g-CNQD. Our method suggests that a variety of g-CNQD-based composites with other semiconductor nanowires can be synthesized for energy applications. PMID:27149607

  10. Ontology for cell-based geographic information

    NASA Astrophysics Data System (ADS)

    Zheng, Bin; Huang, Lina; Lu, Xinhai

    2009-10-01

    Inter-operability is a key notion in geographic information science (GIS) for the sharing of geographic information (GI). That requires a seamless translation among different information sources. Ontology is enrolled in GI discovery to settle the semantic conflicts for its natural language appearance and logical hierarchy structure, which are considered to be able to provide better context for both human understanding and machine cognition in describing the location and relationships in the geographic world. However, for the current, most studies on field ontology are deduced from philosophical theme and not applicable for the raster expression in GIS-which is a kind of field-like phenomenon but does not physically coincide to the general concept of philosophical field (mostly comes from the physics concepts). That's why we specifically discuss the cell-based GI ontology in this paper. The discussion starts at the investigation of the physical characteristics of cell-based raster GI. Then, a unified cell-based GI ontology framework for the recognition of the raster objects is introduced, from which a conceptual interface for the connection of the human epistemology and the computer world so called "endurant-occurrant window" is developed for the better raster GI discovery and sharing.

  11. Sol-gel based biofuel cell architectures

    NASA Astrophysics Data System (ADS)

    Lim, James Robert

    Sol-gel based biofuel cell architectures were investigated and quantified for electrochemical performance. The flexible solution chemistry of the sol-gel process has been used to synthesize bio-hybrid materials in which a wide variety of biomolecules are encapsulated in a transparent, inorganic matrix. These biomolecules retain their characteristic reactivities and spectroscopic properties despite being immobilized in the pores of the inorganic matrix. Stability of the biomolecules is also improved because of the confinement in the rigid inorganic network. Sol-gel immobilization serves as the basis for the electrode architecture used in enzymatic biofuel cells. In this dissertation, the fabrication and characterization of an enzymatic glucoseoxygen biofuel cell that incorporates nanostructured silica sol-gel/carbon nanotube composite electrodes was evaluated. These novel electrodes combine the benefits of sol-gel encapsulation with the use of carbon nanotubes which provide enhanced electronic conduction pathways and increase the effective surface area of the electrode. With this immobilization approach, the silica sol-gel is sufficiently porous that both glucose and oxygen have access to enzymes and yet provide a protective cage that preserves biological structure and function, offers long-term stability and perhaps enables operation at elevated temperatures. In addition, direct electron transfer was exhibited by a nanostructured cathode. More notably, these nanostructured composites were developed for power generation. Analysis of electron transfer rates and enzyme kinetics were used to quantify encapsulation properties and explore potential opportunities for optimization. Another topic for biofuel cells is miniaturization. Through miniaturization, biofuel cell design and integration are major considerations for increasing power density and performance.

  12. New Materials for Chalcogenide Based Solar Cells

    NASA Astrophysics Data System (ADS)

    Tosun, Banu Selin

    Thin film solar cells based on copper indium gallium diselenide (CIGS) have achieved efficiencies exceeding 20 %. The p-n junction in these solar cells is formed between a p-type CIGS absorber layer and a composite n-type film that consists of a 50-100 nm thin n-type CdS followed by a 50-200 nm thin n-type ZnO. This dissertation focuses on developing materials for replacing CdS and ZnO films to improve the damp-heat stability of the solar cells and for minimizing the use of Cd. Specifically, I demonstrate a new CIGS solar cell with better damp heat stability wherein the ZnO layer is replaced with SnO2. The efficiency of solar cells made with SnO2 decreased less than 5 % after 120 hours at 85 °C and 85 % relative humidity while the efficiency of solar cells made with ZnO declined by more than 70 %. Moreover, I showed that a SnO2 film deposited on top of completed CIGS solar cells significantly increased the device lifetime by forming a barrier against water diffusion. Semicrystalline SnO2 films deposited at room temperature had nanocrystals embedded in an amorphous matrix, which resulted in films without grain boundaries. These films exhibited better damp-heat stability than ZnO and crystalline SnO2 films deposited at higher temperature and this difference is attributed to the lack of grain boundary water diffusion. In addition, I studied CBD of Zn1-xCdxS from aqueous solutions of thiourea, ethylenediaminetetraacetic acid and zinc and cadmium sulfate. I demonstrated that films with varying composition (x) can be deposited through CBD and studied the structure and composition variation along the films' thickness. However, this traditional chemical bath deposition (CBD) approach heats the entire solution and wastes most of the chemicals by homogenous particle formation. To overcome this problem, I designed and developed a continuous-flow CBD approach to utilize the chemicals efficiently and to eliminate homogenous particle formation. Only the substrate is heated to

  13. Hemoglobin-based red blood cell substitutes.

    PubMed

    Chang, Thomas Ming Swi

    2004-09-01

    Polyhemoglobin is already well into the final stages of clinical trials in humans with one approved for routine clinical use in South Africa. Conjugated hemoglobin is also in ongoing clinical trials. Meanwhile, recombinant Hb has been modified to modulate the effects of nitric oxide. Other systems contain antioxidant enzymes for those clinical applications that may have potential problems related to ischemia-reperfusion injuries. Other developments are based on hemoglobin-lipid vesicles and also the use of nanotechnology and biodegradable copolymers to prepare nanodimension artificial red blood cells containing hemoglobin and complex enzyme systems.

  14. Cell-Based Therapy for Silicosis

    PubMed Central

    Lopes-Pacheco, Miquéias; Bandeira, Elga; Morales, Marcelo M.

    2016-01-01

    Silicosis is the most common pneumoconiosis globally, with higher prevalence and incidence in developing countries. To date, there is no effective treatment to halt or reverse the disease progression caused by silica-induced lung injury. Significant advances have to be made in order to reduce morbidity and mortality related to silicosis. In this review, we have highlighted the main mechanisms of action that cause lung damage by silica particles and summarized the data concerning the therapeutic promise of cell-based therapy for silicosis. PMID:27066079

  15. Dual Influence of Reduction Annealing on Diffused Hematite/FTO Junction for Enhanced Photoelectrochemical Water Oxidation.

    PubMed

    Yang, Xiaogang; Liu, Rui; Lei, Yan; Li, Pinjiang; Wang, Ke; Zheng, Zhi; Wang, Dunwei

    2016-06-29

    Band structure engineering of the interface between the semiconductor and the conductive substrate may profoundly influence charge separation and transport for photovoltaic and photoelectrochemical devices. In this work, we found that a reduction-annealing treatment resulted in a diffused junction through enhanced interdiffusion of hematite/FTO at the interface. The activated hematite exhibited higher nanoelectric conductivity that was probed by a PeakForce TUNA AFM method. Furthermore, charge accumulation and recombination via surface states at the interface were dramatically reduced after the reduction-annealing activation, which was confirmed by transient surface photovoltage measurements. The diffused hematite junction promises improved photoelectrochemical performance without the need for a buffer layer. PMID:27275513

  16. Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film.

    PubMed

    Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I; Qamaruddin, Muhammad; Yamani, Zain H

    2015-01-01

    Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested. Graphical abstractWO3-surface modified TiO2 film showing better photocatalytic and photoelectrocatalytic activity. PMID:25852351

  17. Platinum monolayer electrocatalyst on gold nanostructures on silicon for photoelectrochemical hydrogen evolution.

    PubMed

    Kye, Joohong; Shin, Muncheol; Lim, Bora; Jang, Jae-Won; Oh, Ilwhan; Hwang, Seongpil

    2013-07-23

    Pt monolayer decorated gold nanostructured film on planar p-type silicon is utilized for photoelectrochemical H2 generation in this work. First, gold nanostructured film on silicon was spontaneously produced by galvanic displacement of the reduction of gold ion and the oxidation of silicon in the presence of fluoride anion. Second, underpotential deposition (UPD) of copper under illumination produced Cu monolayer on gold nanostructured film followed by galvanic exchange of less-noble Cu monolayer with more-noble PtCl6(2-). Pt(shell)/Au(core) on p-type silicon showed the similar activity with platinum nanoparticle on silicon for photoelectrochemical hydrogen evolution reaction in spite of low platinum loading. From Tafel analysis, Pt(shell)/Au(core) electrocatalyst shows the higher area-specific activity than platinum nanoparticle on silicon demonstrating the significant role of underlying gold for charge transfer reaction from silicon to H(+) through platinum catalyst. PMID:23750804

  18. Template synthesis and photoelectrochemical properties of Bi{sub 2}S{sub 3} microflowers

    SciTech Connect

    Cao, Feng; Wang, Jianmin; Tu, Wanhong; Lv, Xin; Li, Song; Qin, Gaowu

    2015-08-15

    Highlights: • Bi{sub 2}S{sub 3} microflowers were fabricated by using a sacrificial-template method. • The effect of the specific experimental parameters was examined. • Photoelectrochemical measurements were characterized. - Abstract: Uniform hierarchical Bi{sub 2}S{sub 3} nanostructures were fabricated by using Bi{sub 2}O{sub 2}CO{sub 3} nanoflowers as a sacrificial template through a hydrothermal reaction with an aqueous L-cysteine solution. Multiple techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Mott–Schottky (M–S) plot and electrochemical impedance spectroscopy (EIS) were applied to investigate the structure, morphology and photoelectrochemical properties of the as-prepared samples. This work demonstrated a simple and cost-effective strategy for the design and fabrication of well-defined complex hierarchical nanomaterials, which can be potentially used in energy storage and conversion devices.

  19. Photoelectrochemical and physical properties of titanium dioxide films obtained by aerosol pyrolysis

    SciTech Connect

    Belaidi, A.; Chaqour, S.M.; Gorochov, O.; Neumann-Spallart, M

    2004-04-02

    Aerosol pyrolysis (AP) was used to prepare thin films of titanium dioxide on various substrates. The films were characterized by SEM, SIMS, XRD, and thickness measurements, and by photoelectrochemical response before and after annealing in various ambients. Pinhole-free anatase films of thickness up to 1000 nm were prepared. Incident photon to current efficiencies (IPCEs) of up to 20% at 365 nm were obtained for thick films under depletion conditions, in aqueous electrolytes.

  20. Enhanced performance of dye-sensitized solar cells using gold nanoparticles modified fluorine tin oxide electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Dingwen; Wang, Milton; Brolo, Alexandre G.; Shen, Jie; Li, Xiaodong; Huang, Sumei

    2013-01-01

    We have investigated plasmon-assisted energy conversion in dye-sensitized solar cells (DSCs) applying gold nanoparticles (NPs) modified fluorine tin oxide (FTO) electrodes. A series of Au NPs with different sizes (15-80 nm) were synthesized and immobilized onto FTO glass slides. Photoanodes were prepared on these Au modified FTO substrates using P25 TiO2 powders and by the screen-printing method. The size effects of Au NPs on the photovoltaic performance of the formed DSCs were investigated systematically. Structural and photoelectrochemical properties of the formed photoanodes were examined by field emission scanning electron microscopy and electrochemical impedance spectroscopy. It was found that the energy conversion efficiency of the DSC was highly dependent on the Au particle size. When the particle size was not greater than 60 nm, the DSC based on the Au NP-FTO composite electrode showed a higher short-circuit current density and better photovoltaic (PV) performance than the cell based on the bare FTO. The best cell was achieved using 25 nm sized Au NPs modified FTO. It exhibited a conversion efficiency of 6.69%, which was 15% higher than that of DSCs without Au NPs. The related PV performance enhancement mechanisms, photoelectrochemical processes and surface-plasmon resonances in DSCs with Au nanostructures are analysed and discussed.

  1. Controlled fabrication of Sn/TiO2 nanorods for photoelectrochemical water splitting

    PubMed Central

    2013-01-01

    In this work, we investigate the controlled fabrication of Sn-doped TiO2 nanorods (Sn/TiO2 NRs) for photoelectrochemical water splitting. Sn is incorporated into the rutile TiO2 nanorods with Sn/Ti molar ratios ranging from 0% to 3% by a simple solvothermal synthesis method. The obtained Sn/TiO2 NRs are single crystalline with a rutile structure. The concentration of Sn in the final nanorods can be well controlled by adjusting the molar ratio of the precursors. Photoelectrochemical experiments are conducted to explore the photocatalytic activity of Sn/TiO2 NRs with different doping levels. Under the illumination of solar simulator with the light intensity of 100 mW/cm2, our measurements reveal that the photocurrent increases with increasing doping level and reaches the maximum value of 1.01 mA/cm2 at −0.4 V versus Ag/AgCl, which corresponds to up to about 50% enhancement compared with the pristine TiO2 NRs. The Mott-Schottky plots indicate that incorporation of Sn into TiO2 nanorod can significantly increase the charge carrier density, leading to enhanced conductivity of the nanorod. Furthermore, we demonstrate that Sn/TiO2 NRs can be a promising candidate for photoanode in photoelectrochemical water splitting because of their excellent chemical stability. PMID:24191909

  2. Photoelectrochemical reduction of CO{sub 2} using silicate rock powder

    SciTech Connect

    Ohta, Kiyohisa; Ohguchi, Youko; Kaneco, Satochi

    1996-12-31

    Until now, numerous investigators have reported chemical fixation of carbon dioxide, such as electrochemical, photochemical and photoelectrochemical reductions. In these methods, relatively, a few studies on the photoelectrochemical conversion of CO{sub 2} have been reported. We have recently presented a photochemical reduction of carbon dioxide and hydrogen formation by using andesite sands as a photocatalyst under sunlight irradiation. At ambient temperature and atmospheric pressure, 6.5 {times} 10{sup -2} ml g{sup -1} methane and 7.0 {times} 10{sup -2} ml g{sup -1} of hydrogen were formed from carbon dioxide and water on the andesite. This report presents the photoelectrochemical reduction of CO{sub 2} using silicate rock (andesite) powder suspended in water. Carbon dioxide is the end product to complete combustion of all fossil fuels. The generation of carbon dioxide is the primary cause for the greenhouse effect. However, carbon dioxide is a potential carbon source. To utilize such a plentiful carbon source, it has been considered carbon dioxide as a feedstock for organic synthesis of carbonyl- and carboxyl-containing compounds or as an oxidant for oxidative synthesis of more valuable organics.

  3. Zinc oxide inverse opal electrodes modified by glucose oxidase for electrochemical and photoelectrochemical biosensor.

    PubMed

    Xia, Lei; Song, Jian; Xu, Ru; Liu, Dali; Dong, Biao; Xu, Lin; Song, Hongwei

    2014-09-15

    The ZnO inverse opal photonic crystals (IOPCs) were synthesized by the sol-gel method using the polymethylmethacrylate (PMMA) as a template. For glucose detection, glucose oxidase (GOD) was further immobilized on the inwall and surface of the IOPCs. The biosensing properties toward glucose of the Nafion/GOD/ZnO IOPCs modified FTO electrodes were carefully studied and the results indicated that the sensitivity of ZnO IOPCs modified electrode was 18 times than reference electrode due to the large surface area and uniform porous structure of ZnO IOPCs. Moreover, photoelectrochemical detection for glucose using the electrode was realized and the sensitivity approached to 52.4 µA mM(-1) cm(-2), which was about four times to electrochemical detection (14.1 µA mM(-1) cm(-2)). It indicated that photoelectrochemical detection can highly improve the sensor performance than conventional electrochemical method. It also exhibited an excellent anti-interference property and a good stability at the same time. This work provides a promising approach for realizing excellent photoelectrochemical biosensor of similar semiconductor photoelectric material. PMID:24752145

  4. Zinc oxide inverse opal electrodes modified by glucose oxidase for electrochemical and photoelectrochemical biosensor.

    PubMed

    Xia, Lei; Song, Jian; Xu, Ru; Liu, Dali; Dong, Biao; Xu, Lin; Song, Hongwei

    2014-09-15

    The ZnO inverse opal photonic crystals (IOPCs) were synthesized by the sol-gel method using the polymethylmethacrylate (PMMA) as a template. For glucose detection, glucose oxidase (GOD) was further immobilized on the inwall and surface of the IOPCs. The biosensing properties toward glucose of the Nafion/GOD/ZnO IOPCs modified FTO electrodes were carefully studied and the results indicated that the sensitivity of ZnO IOPCs modified electrode was 18 times than reference electrode due to the large surface area and uniform porous structure of ZnO IOPCs. Moreover, photoelectrochemical detection for glucose using the electrode was realized and the sensitivity approached to 52.4 µA mM(-1) cm(-2), which was about four times to electrochemical detection (14.1 µA mM(-1) cm(-2)). It indicated that photoelectrochemical detection can highly improve the sensor performance than conventional electrochemical method. It also exhibited an excellent anti-interference property and a good stability at the same time. This work provides a promising approach for realizing excellent photoelectrochemical biosensor of similar semiconductor photoelectric material.

  5. Flame Synthesized Single Crystal Nanocolumn-Structured WO3 Thin Films for Photoelectrochemical Water Splitting.

    PubMed

    Ding, Jin-Rui; Kim, Kyo-Seon

    2016-02-01

    Tungsten oxide thin films have been found as an active visible light driven photoanode material for photoelectrochemical water splitting due to its good stability in aqueous solution and energetically favorable valence band position for water oxidation. Morphology control, which determines the performance of WO3 photoanode, is one of most focuses of recent research interests. In this work, we successfully prepared monoclinic WO3 thin films on ITO glass at low range of substrate temperature with a fabrication rate around 100 nm per minute by using aerosol flame deposition process. Single crystal nanocolumns with both triangular pyramid-like and triangular prism-like structure were obtained at certain process conditions. Photoelectrochemical properties of photoelectrodes assembled with both structured WO3 thin films were investigated. The prism-like nanocolumn-structured thin film generated the current density of 1.58 mAcm(-2) at potential of 1.0 V versus Ag/AgCl in 0.5 M H2SO4 solution under illumination of AM 1.5 simulated solar light (100 mVcm(-2)). It presented superior photoelectrochemical performance to pyramid-like nanocolumn-structured WO3 thin film. PMID:27433624

  6. Applications of light-induced electron-transfer and hydrogen-abstraction processes: photoelectrochemical production of hydrogen from reducing radicals

    SciTech Connect

    Chandrasekaran, K.; Whitten, D.G.

    1980-07-16

    A study of several photoprocesses which generate reducing radicals in similar photoelectrochemical cells was reported. Coupling of a light-induced reaction to produce a photocurrent concurrent with hydrogen generation in a second compartment can occur for a number of electron transfers and hydrogen abstractions in what appears to be a fairly general process. Irradiation of the RuL/sub 3//sup +2//Et/sub 3/N: photoanode compartment leads to production of a photocurrent together with generation of hydrogen at the cathode. A rather different type of reaction that also results in formation of two reducing radicals as primary photoproducts if the photoreduction of ketones and H-heteroaromatics by alcohols and other hydrogen atom donors. Irradiation of benzophenone/2-propanol/MV/sup +2/ solutions in the photoanode compartment (intensity 1.4 x 10/sup -8/ einstein/s) leads to a buildup of moderate levels of MV/sup +/ and to a steady photocurrent of 320 ..mu..A. The MV/sup +/ is oxidized at the anode of the photolyzed compartment with concomitant reduction of H/sup +/ in the cathode compartment. There was no decrease in benzophenone concentration over moderate periods of irradiation, and a steady production of hydrogen in the cathode compartment was observed. The photocurrent produced was linear with the square of absorbed light intensity. The quantum efficiency at the above-indicated intensity is 22%; quantitative analysis of the hydrogen produced gives good agreement with this value. 1 figure, 1 table. (DP)

  7. Ultrasensitive photoelectrochemical immunoassay of antibody against tumor-associated carbohydrate antigen amplified by functionalized graphene derivates and enzymatic biocatalytic precipitation.

    PubMed

    Zhang, Xiaoru; Liu, Mingshuai; Mao, Yaning; Xu, Yunpeng; Niu, Shuyan

    2014-09-15

    Tumor-associated carbohydrate antigens (TACAs) are often found on the surface of cancer cells. The determination of the carbohydrate components of glycoconjugates is challenging because of the chemical complexity of glycan chains. Through monitoring corresponding antibody, we can get a good solution for clinical diagnosis. Here breast tumor-associated carbohydrate antigens Tn were used as a model and a new photoelectrochemical biosensor for ultrasensitive detection of antibody against Tn was developed. To enhance the sensitivity, both graphene oxide and graphene were used during the construction of biosensor. Through the formation of immunocomplex and the insoluble biocatalytic precipitation (BCP) product, photocurrent intensity was decreased greatly and the antibody could be detected from 0.5 to 500 pg/mL with a detection limit of 1.0×10(-13) g/mL. At the same time, the developed biosensor showed acceptable selectivity and could be used in the complex matrix. Compared with the traditional glycoarray method, this PEC method is more sensitive (5 orders of magnitude), and thus provides another platform to monitor the immune response to carbohydrate epitopes at different stages during differentiation, metastasis, or treatment.

  8. Carbon quantum dots as novel sensitizers for photoelectrochemical solar hydrogen generation and their size-dependent effect

    NASA Astrophysics Data System (ADS)

    Yu, Xuelian; Liu, Rongji; Zhang, Guangjin; Cao, Hongbin

    2013-08-01

    As a result of global energy needs, much research has been devoted to the conversion of solar energy to various usable forms, such as chemical energy in the form of hydrogen via water splitting. To make the conversion methods efficient, economically practical, and industrially scalable, sensitizers capable of utilizing visible and near infrared (IR) light need to be developed. Herein, water-soluble, colloidally stable carbon quantum dots (CQDs) are successfully synthesized by a facile one-step alkali-assisted electrochemical method. Owing to their broad visible light absorption, upconversion luminescence properties and efficient electron injection to TiO2, these CQDs can be used as the sensitizer for photoelectrochemical cells and show an optimized photocurrent of 1.2 mA cm-2 at 0 V versus Ag/AgCl under 100 mW cm-2 simulated sunlight. The above results indicate that the elementally abundant and environmentally friendly CQDs, as a novel sensitizer, can surely be employed to make full use of the visible spectrum of sunlight for their application in photovoltaic devices.

  9. TOPICAL REVIEW: Stem cells engineering for cell-based therapy

    NASA Astrophysics Data System (ADS)

    Taupin, Philippe

    2007-09-01

    Stem cells carry the promise to cure a broad range of diseases and injuries, from diabetes, heart and muscular diseases, to neurological diseases, disorders and injuries. Significant progresses have been made in stem cell research over the past decade; the derivation of embryonic stem cells (ESCs) from human tissues, the development of cloning technology by somatic cell nuclear transfer (SCNT) and the confirmation that neurogenesis occurs in the adult mammalian brain and that neural stem cells (NSCs) reside in the adult central nervous system (CNS), including that of humans. Despite these advances, there may be decades before stem cell research will translate into therapy. Stem cell research is also subject to ethical and political debates, controversies and legislation, which slow its progress. Cell engineering has proven successful in bringing genetic research to therapy. In this review, I will review, in two examples, how investigators are applying cell engineering to stem cell biology to circumvent stem cells' ethical and political constraints and bolster stem cell research and therapy.

  10. Cellulose nanofiber-templated three-dimension TiO2 hierarchical nanowire network for photoelectrochemical photoanode

    NASA Astrophysics Data System (ADS)

    Li, Zhaodong; Yao, Chunhua; Wang, Fei; Cai, Zhiyong; Wang, Xudong

    2014-12-01

    Three dimensional (3D) nanostructures with extremely large porosity possess a great promise for the development of high-performance energy harvesting and storage devices. In this paper, we developed a high-density 3D TiO2 fiber-nanorod (NR) heterostructure for efficient photoelectrochemical (PEC) water splitting. The hierarchical structure was synthesized on a ZnO-coated cellulose nanofiber (CNF) template using atomic layer deposition (ALD)-based thin film and NR growth procedures. The tubular structure evolution was in good agreement with the recently discovered vapor-phase Kirkendall effect in high-temperature ALD processes. The NR morphology was formed via the surface-reaction-limited pulsed chemical vapor deposition (SPCVD) mechanism. Under Xenon lamp illumination without and with an AM 1.5G filter or a UV cut off filter, the PEC efficiencies of a 3D TiO2 fiber-NR heterostructure were found to be 22-249% higher than those of the TiO2-ZnO bilayer tubular nanofibers and TiO2 nanotube networks that were synthesized as reference samples. Such a 3D TiO2 fiber-NR heterostructure offers a new route for a cellulose-based nanomanufacturing technique, which can be used for large-area, low-cost, and green fabrication of nanomaterials as well as their utilizations for efficient solar energy harvesting and conversion.

  11. Microwave-assisted self-doping of TiO2 photonic crystals for efficient photoelectrochemical water splitting.

    PubMed

    Zhang, Zhonghai; Yang, Xiulin; Hedhili, Mohamed Nejib; Ahmed, Elaf; Shi, Le; Wang, Peng

    2014-01-01

    In this article, we report that the combination of microwave heating and ethylene glycol, a mild reducing agent, can induce Ti(3+) self-doping in TiO2. A hierarchical TiO2 nanotube array with the top layer serving as TiO2 photonic crystals (TiO2 NTPCs) was selected as the base photoelectrode. The self-doped TiO2 NTPCs demonstrated a 10-fold increase in visible-light photocurrent density compared to the nondoped one, and the optimized saturation photocurrent density under simulated AM 1.5G illumination was identified to be 2.5 mA cm(-2) at 1.23 V versus reversible hydrogen electrode, which is comparable to the highest values ever reported for TiO2-based photoelectrodes. The significant enhancement of photoelectrochemical performance can be ascribed to the rational coupling of morphological and electronic features of the self-doped TiO2 NTPCs: (1) the periodically morphological structure of the photonic crystal layer traps broadband visible light, (2) the electronic interband state induced from self-doping of Ti(3+) can be excited in the visible-light region, and (3) the captured light by the photonic crystal layer is absorbed by the self-doped interbands.

  12. Inorganic-organic solar cells based on quaternary sulfide as absorber materials.

    PubMed

    Hong, Tiantian; Liu, Zhifeng; Yan, Weiguo; Liu, Junqi; Zhang, Xueqi

    2015-12-14

    We report a novel promising quaternary sulfide (CuAgInS) to serve as a semiconductor sensitizer material in the photoelectrochemical field. In this study, CuAgInS (CAIS) sulfide sensitized ZnO nanorods were fabricated on ITO substrates through a facile and low-cost hydrothermal chemical method and applied on photoanodes for solar cells for the first time. The component and stoichiometry were key factors in determining the photoelectric performance of CAIS sulfide, which were controlled by modulating their reaction time. ZnO/Cu0.7Ag0.3InS2 nanoarrays exhibit an enhanced optical and photoelectric performance and the power conversion efficiency of ITO/ZnO/Cu0.7Ag0.3InS2/P3HT/Pt solid-state solar cell was up to 1.80%. The remarkable performance stems from improved electron transfer, a higher efficiency of light-harvesting and appropriate band gap alignment at the interface of the ZnO/Cu0.7Ag0.3InS2 NTs. The research indicates that CAIS as an absorbing material has enormous potential in solar cell systems.

  13. Inorganic-organic solar cells based on quaternary sulfide as absorber materials.

    PubMed

    Hong, Tiantian; Liu, Zhifeng; Yan, Weiguo; Liu, Junqi; Zhang, Xueqi

    2015-12-14

    We report a novel promising quaternary sulfide (CuAgInS) to serve as a semiconductor sensitizer material in the photoelectrochemical field. In this study, CuAgInS (CAIS) sulfide sensitized ZnO nanorods were fabricated on ITO substrates through a facile and low-cost hydrothermal chemical method and applied on photoanodes for solar cells for the first time. The component and stoichiometry were key factors in determining the photoelectric performance of CAIS sulfide, which were controlled by modulating their reaction time. ZnO/Cu0.7Ag0.3InS2 nanoarrays exhibit an enhanced optical and photoelectric performance and the power conversion efficiency of ITO/ZnO/Cu0.7Ag0.3InS2/P3HT/Pt solid-state solar cell was up to 1.80%. The remarkable performance stems from improved electron transfer, a higher efficiency of light-harvesting and appropriate band gap alignment at the interface of the ZnO/Cu0.7Ag0.3InS2 NTs. The research indicates that CAIS as an absorbing material has enormous potential in solar cell systems. PMID:26553746

  14. Photoelectrochemical etching of silicon carbide (SiC) and its characterization

    NASA Technical Reports Server (NTRS)

    Collins, D. M.; Harris, G. L.; Wongchotigul, K.

    1995-01-01

    Silicon carbide (SiC) is an attractive semiconductor material for high speed, high density, and high temperature device applications due to its wide bandgap (2.2-3.2 eV), high thermal conductivity, and high breakdown electric field (4 x 10(exp 6) V/cm). An instrumental process in the fabrication of semiconductor devices is the ability to etch in a highly controlled and selective manner for direct patterning techniques. A novel technique in etching using electrochemistry is described. This procedure involves the ultraviolet (UV) lamp-assisted photoelectrochemical etching of n-type 3C- and 6H-SiC to enhance the processing capability of device structures in SiC. While under UV illumination, the samples are anodically biased in an HF based aqueous solution since SiC has photoconductive properties. In order for this method to be effective, the UV light must be able to enhance the production of holes in the SiC during the etching process thus providing larger currents with light from the photocurrents generated than those currents with no light. Otherwise dark methods would be used as in the case of p-type 3C-SiC. Experiments have shown that the I/V characteristics of the SiC-electrolyte interface reveal a minimum etch voltage of 3 V and 4 V for n- and p-type 3C-SiC, respectively. Hence it is possible for etch-stops to occur. Etch rates calculated have been as high as 0.67 micrometer/min for p-type, 1.4 micrometer/min for n-type, and 1.1 micrometer/min for pn layer. On n-type 3C- SiC, an oxide formation is present where after etching a yellowish layer corresponds to a low Si/C ratio and a white layer corresponds to a high Si/C ratio. P-type 3C-SiC shows a grayish layer. Additionally, n-type 6H-SiC shows a brown layer with a minimum etch voltage of 3 V.

  15. Ischemic preconditioning for cell-based therapy and tissue engineering.

    PubMed

    Hsiao, Sarah T; Dilley, Rodney J; Dusting, Gregory J; Lim, Shiang Y

    2014-05-01

    Cell- and tissue-based therapies are innovative strategies to repair and regenerate injured hearts. Despite major advances achieved in optimizing these strategies in terms of cell source and delivery method, the clinical outcome of cell-based therapy remains unsatisfactory. The non-genetic approach of ischemic/hypoxic preconditioning to enhance cell- and tissue-based therapies has received much attention in recent years due to its non-invasive drug-free application. Here we discuss the current development of hypoxic/ischemic preconditioning to enhance stem cell-based cardiac repair and regeneration.

  16. Laser-based direct-write techniques for cell printing

    PubMed Central

    Schiele, Nathan R; Corr, David T; Huang, Yong; Raof, Nurazhani Abdul; Xie, Yubing; Chrisey, Douglas B

    2016-01-01

    Fabrication of cellular constructs with spatial control of cell location (±5 μm) is essential to the advancement of a wide range of applications including tissue engineering, stem cell and cancer research. Precise cell placement, especially of multiple cell types in co- or multi-cultures and in three dimensions, can enable research possibilities otherwise impossible, such as the cell-by-cell assembly of complex cellular constructs. Laser-based direct writing, a printing technique first utilized in electronics applications, has been adapted to transfer living cells and other biological materials (e.g., enzymes, proteins and bioceramics). Many different cell types have been printed using laser-based direct writing, and this technique offers significant improvements when compared to conventional cell patterning techniques. The predominance of work to date has not been in application of the technique, but rather focused on demonstrating the ability of direct writing to pattern living cells, in a spatially precise manner, while maintaining cellular viability. This paper reviews laser-based additive direct-write techniques for cell printing, and the various cell types successfully laser direct-written that have applications in tissue engineering, stem cell and cancer research are highlighted. A particular focus is paid to process dynamics modeling and process-induced cell injury during laser-based cell direct writing. PMID:20814088

  17. Efficient Electrochemical and Photoelectrochemical H2 Production from Water by a Cobalt Dithiolene One-Dimensional Metal-Organic Surface.

    PubMed

    Downes, Courtney A; Marinescu, Smaranda C

    2015-11-01

    Solar-driven hydrogen evolution from water has emerged as an important methodology for the storage of renewable energy in chemical bonds. Efficient and practical clean-energy devices for electrochemical or photoelectrochemical splitting of water require the immobilization of stable and active hydrogen-evolving catalysts onto electrode or photocathode materials, which remains a significant challenge. Here we show that cobalt(II) reacts with benzene-1,2,4,5-tetrathiol in the presence of base to form a cobalt dithiolene polymer 1. The generated polymer is immobilized onto glassy carbon electrodes (GCE) to generate a metal-organic surface (MOS 1|GCE), which displays efficient H2-evolving activity and stability in acidic aqueous solutions. Moreover, the generated polymer is integrated with planar p-type Si to generate very efficient photocathode materials (MOS 1|Si) for solar-driven hydrogen production from water. Photocurrents up to 3.8 mA/cm(2) at 0 V vs RHE were achieved under simulated 1 Sun illumination. MOS 1|Si photocathodes operate at potentials 550 mV more positive than MOS 1|GCE cathodes to reach the same activity for H2 evolution from water (1 mA/cm(2)).

  18. A sensitive and label-free photoelectrochemical aptasensor using Co-doped ZnO diluted magnetic semiconductor nanoparticles.

    PubMed

    Li, Hongbo; Qiao, Yunfei; Li, Jing; Fang, Hailin; Fan, Dahe; Wang, Wei

    2016-03-15

    Co-doped ZnO diluted magnetic semiconductor as a novel photoelectric beacon was first constructed for photoelectrochemical (PEC) aptasensor of acetamiprid. The fabricated PEC sensing is based on the specific binding of acetamiprid and its aptamer, which induces the decreasement of enhanced photocurrent produced by the electron donor of quercetin. Co(2+) doping has a beneficial effect in extending the band width of light absorption of ZnO into the visible region and to promote the separation of the photoinduced carriers due to the sp-d exchange interactions existing between the band electrons and the localized d electrons of Co(2+). The fabricated aptasensor was linear with the concentration of acetamiprid in the range of 0.5-800 nmolL(-1) with the detection limit of 0.18 nmolL(-1). The presence of same concentration of other conventional pesticides did not interfere in the detection of acetamiprid and the recovery is between 96.2% and 103.7%. This novel PEC aptasensor has good performances with high sensitivity, good selectivity, low cost and portable features. The strategy of Co-doped ZnO diluted magnetic semiconductor paves a new way to improve the performances of PEC aptasensor.

  19. Femtomole level photoelectrochemical aptasensing for mercury ions using quercetin-copper(II) complex as the DNA intercalator.

    PubMed

    Li, Hongbo; Xue, Yan; Wang, Wei

    2014-04-15

    An ultrasensitive and selective photoelectrochemical (PEC) aptasensor for mercury ions was first fabricated based on perylene-3, 4, 9, 10-tetracarboxylic acid/graphene oxide (PTCA/GO) heterojunction using quercetin-copper(II) complex intercalated into the poly(dT)-poly(dA) duplexes. Both the PTCA/GO heterojunction and the quercetin-copper(II) complex are in favor of the sensitivity for the fabricated PEC aptasensor due to band alignment and strong reduction capability, respectively. And they efficiently promote the separation of photoexcited carriers and enhance the photocurrent. The formation of thymine-Hg(2+)-thymine coordination chemistry resulted in the dehybridization of poly(dT)-poly(dA) duplexes and then the intercalator quercetin-copper(II) complex broke away from the surface of the PEC aptasensor. As the concentration of mercury ions increased, the photocurrent gradually decreased. The electrode response for mercury ions detection was in the linear range from 0.01 pmol L(-1) to 1.00 pmol L(-1) with the detection limit of 3.33 fmol L(-1). The label-free PEC aptasensor has excellent performances with ultrasensitivity and good selectivity besides the advantage of economic and facile fabrication. The strategy of quercetin-copper(II) complex as a novel DNA intercalator paves a new way to improve the performances for PEC sensors. PMID:24291750

  20. A femtomolar level and highly selective 17β-estradiol photoelectrochemical aptasensor applied in environmental water samples analysis.

    PubMed

    Fan, Lifang; Zhao, Guohua; Shi, Huijie; Liu, Meichuan; Wang, Yanbin; Ke, Hongyang

    2014-05-20

    Driven by the urgent demand of determining low level of 17β-estradiol (E2) present in environment, a novel and ultrasensitive photoelectrochemical (PEC) sensing platform based on anti-E2 aptamer as the biorecognition element was developed onto CdSe nanoparticles-modified TiO2 nanotube arrays. The designed PEC aptasensor exhibits excellent performances in determination of E2 with a wide linear range of 0.05-15 pM. The detection limit of 33 fM is lower than the previous reports. The aptasensor manifests outstanding selectivity to E2 while used to detect seven other endocrine disrupting compounds that have similar structure or coexist with E2. The superior sensing behavior toward E2 can be attributed to the appropriate PEC sensing interface resulting from the preponderant tubular microstructure and excellent photoelectrical activity, the large packing density of aptamer on the sensing interface, as well as the high affinity of the aptamer to E2. The PEC aptasensor was applied successfully to determine E2 in environmental water samples without complicate sample pretreatments, and the analytical results showed good agreement with that determined by HPLC. Thus, a simple and rapid PEC technique for detection low level of E2 was established, having promising potential in monitoring environmental water pollution.

  1. A sensitive and label-free photoelectrochemical aptasensor using Co-doped ZnO diluted magnetic semiconductor nanoparticles.

    PubMed

    Li, Hongbo; Qiao, Yunfei; Li, Jing; Fang, Hailin; Fan, Dahe; Wang, Wei

    2016-03-15

    Co-doped ZnO diluted magnetic semiconductor as a novel photoelectric beacon was first constructed for photoelectrochemical (PEC) aptasensor of acetamiprid. The fabricated PEC sensing is based on the specific binding of acetamiprid and its aptamer, which induces the decreasement of enhanced photocurrent produced by the electron donor of quercetin. Co(2+) doping has a beneficial effect in extending the band width of light absorption of ZnO into the visible region and to promote the separation of the photoinduced carriers due to the sp-d exchange interactions existing between the band electrons and the localized d electrons of Co(2+). The fabricated aptasensor was linear with the concentration of acetamiprid in the range of 0.5-800 nmolL(-1) with the detection limit of 0.18 nmolL(-1). The presence of same concentration of other conventional pesticides did not interfere in the detection of acetamiprid and the recovery is between 96.2% and 103.7%. This novel PEC aptasensor has good performances with high sensitivity, good selectivity, low cost and portable features. The strategy of Co-doped ZnO diluted magnetic semiconductor paves a new way to improve the performances of PEC aptasensor. PMID:26436325

  2. Fabrication and Enhanced Photoelectrochemical Performance of MoS₂/S-Doped g-C₃N₄ Heterojunction Film.

    PubMed

    Ye, Lijuan; Wang, Dan; Chen, Shijian

    2016-03-01

    We report on a novel MoS2/S-doped g-C3N4 heterojunction film with high visible-light photoelectrochemical (PEC) performance. The heterojunction films are prepared by CVD growth of S-doped g-C3N4 film on indium-tin oxide (ITO) glass substrates, with subsequent deposition of a low bandgap, 1.69 eV, visible-light response MoS2 layer by hydrothermal synthesis. Adding thiourea into melamine as the coprecursor not only facilitates the growth of g-C3N4 films but also introduces S dopants into the films, which significantly improves the PEC performance. The fabricated MoS2/S-doped g-C3N4 heterojunction film offers an enhanced anodic photocurrent of as high as ∼1.2 × 10(-4) A/cm(2) at an applied potential of +0.5 V vs Ag/AgCl under the visible light irradiation. The enhanced PEC performance of MoS2/S-doped g-C3N4 film is believed due to the improved light absorption and the efficient charge separation of the photogenerated charge at the MoS2/S-doped g-C3N4 interface. The convenient preparation of carbon nitride based heterojunction films in this work can be widely used to design new heterojunction photoelectrodes or photocatalysts with high performance for H2 evolution.

  3. Cu2O/CuO Bilayered Composite as a High-Efficiency Photocathode for Photoelectrochemical Hydrogen Evolution Reaction

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Xu, Di; Wu, Qingyong; Diao, Peng

    2016-10-01

    Solar powered hydrogen evolution reaction (HER) is one of the key reactions in solar-to-chemical energy conversion. It is desirable to develop photocathodic materials that exhibit high activity toward photoelectrochemical (PEC) HER at more positive potentials because a higher potential means a lower overpotential for HER. In this work, the Cu2O/CuO bilayered composites were prepared by a facile method that involved an electrodeposition and a subsequent thermal oxidation. The resulting Cu2O/CuO bilayered composites exhibited a surprisingly high activity and good stability toward PEC HER, expecially at high potentials in alkaline solution. The photocurrent density for HER was 3.15 mA·cm‑2 at the potential of 0.40 V vs. RHE, which was one of the two highest reported at the same potential on copper-oxide-based photocathode. The high photoactivity of the bilayered composite was ascribed to the following three advantages of the Cu2O/CuO heterojunction: (1) the broadened light absorption band that made more efficient use of solar energy, (2) the large space-charge-region potential that enabled a high efficiency for electron-hole separation, and (3) the high majority carrier density that ensured a faster charge transportation rate. This work reveals the potential of the Cu2O/CuO bilayered composite as a promising photocathodic material for solar water splitting.

  4. Cu2O/CuO Bilayered Composite as a High-Efficiency Photocathode for Photoelectrochemical Hydrogen Evolution Reaction

    PubMed Central

    Yang, Yang; Xu, Di; Wu, Qingyong; Diao, Peng

    2016-01-01

    Solar powered hydrogen evolution reaction (HER) is one of the key reactions in solar-to-chemical energy conversion. It is desirable to develop photocathodic materials that exhibit high activity toward photoelectrochemical (PEC) HER at more positive potentials because a higher potential means a lower overpotential for HER. In this work, the Cu2O/CuO bilayered composites were prepared by a facile method that involved an electrodeposition and a subsequent thermal oxidation. The resulting Cu2O/CuO bilayered composites exhibited a surprisingly high activity and good stability toward PEC HER, expecially at high potentials in alkaline solution. The photocurrent density for HER was 3.15 mA·cm−2 at the potential of 0.40 V vs. RHE, which was one of the two highest reported at the same potential on copper-oxide-based photocathode. The high photoactivity of the bilayered composite was ascribed to the following three advantages of the Cu2O/CuO heterojunction: (1) the broadened light absorption band that made more efficient use of solar energy, (2) the large space-charge-region potential that enabled a high efficiency for electron-hole separation, and (3) the high majority carrier density that ensured a faster charge transportation rate. This work reveals the potential of the Cu2O/CuO bilayered composite as a promising photocathodic material for solar water splitting. PMID:27748380

  5. Molecular imaging of cell-based cancer immunotherapy

    PubMed Central

    Liu, Gang; Swierczewska, Magdalena; Zhang, Xiaoming

    2011-01-01

    Cell-based cancer immunotherapy represents a new and powerful weapon in the arsenal of anticancer treatments. Non-invasive monitoring of the disposition, migration and destination of therapeutic cells will facilitate the development of cell based therapy. The therapeutic cells can be modified intrinsically by a reporter gene or labeled extrinsically by introducing imaging probes into the cells or on the cell surface before transplant. Various advanced non-invasive molecular imaging techniques are playing important roles in optimizing cellular therapy by tracking cells and monitoring the therapeutic effects of transplanted cells in vivo. This review will summarize the application of multiple molecular imaging modalities in cell-based cancer immunotherapy. PMID:21308113

  6. Using silver nanocluster/graphene nanocomposite to enhance photoelectrochemical activity of CdS:Mn/TiO2 for highly sensitive signal-on immunoassay.

    PubMed

    Song, Jie; Wang, Jiamian; Wang, Xiuyun; Zhao, Wei; Zhao, Yanqiu; Wu, Shuo; Gao, Zhanming; Yuan, Jingli; Meng, Changgong

    2016-06-15

    A highly sensitive signal-on photoelectrochemical (PEC) immunosensor was fabricated here using CdS:Mn/TiO2 as photoelectrochemical sensing platform, and silver nanoclusters and graphene naocomposites (AgNCs-GR) as signal amplification tags. The immunosensor was constructed based on the specific sandwich immunoreaction, and the photo-to-current conversion efficiency of the isolated protein modified CdS:Mn/TiO2 matrix was improved based on the synergistic effect of AgNCs-GR. Under irradiation, the photogenerated electrons from the AgNCs at a higher conduction band edge level could be transport to the CdS:Mn/TiO2 matrix with the assistance of highly conductive graphene nanosheets, as well as recycle the trapped excitons in the defects-rich CdS:Mn/TiO2 interface. The electron transport and exciton recycle reduced the possibility of electron-hole recombination and greatly improved the photo-to-current conversion efficiency of the sensing matrix. Based on the signal enhancement, a signal-on PEC immunosensors was fabricated for the detection of carcinoembryonic antigen (CEA), a model analyte related to many malignant diseases. Under optimal conditions, the as-prepared immunosensor showed excellent analytical performance, with a wide linear range from 1.0 pg/mL to 100 ng/mL and a low limit of detection of 1.0 pg/mL. The signal-on mode provided 2.48 times higher sensitivity compared with signal-off mode. This strategy demonstrated good accuracy and high selectivity for practical sample analysis, thus may have great application prospective in the prediction and early diagnosis of diseases. PMID:26901458

  7. Cell-based therapy approaches: the hope for incurable diseases.

    PubMed

    Buzhor, Ella; Leshansky, Lucy; Blumenthal, Jacob; Barash, Hila; Warshawsky, David; Mazor, Yaron; Shtrichman, Ronit

    2014-01-01

    Cell therapies aim to repair the mechanisms underlying disease initiation and progression, achieved through trophic effect or by cell replacement. Multiple cell types can be utilized in such therapies, including stem, progenitor or primary cells. This review covers the current state of cell therapies designed for the prominent disorders, including cardiovascular, neurological (Parkinson's disease, amyotrophic lateral sclerosis, stroke, spinal cord injury), autoimmune (Type 1 diabetes, multiple sclerosis, Crohn's disease), ophthalmologic, renal, liver and skeletal (osteoarthritis) diseases. Various cell therapies have reached advanced clinical trial phases with potential marketing approvals in the near future, many of which are based on mesenchymal stem cells. Advances in pluripotent stem cell research hold great promise for regenerative medicine. The information presented in this review is based on the analysis of the cell therapy collection detailed in LifeMap Discovery(®) (LifeMap Sciences Inc., USA) the database of embryonic development, stem cell research and regenerative medicine. PMID:25372080

  8. Recent developments in cell-based immune therapy for neuroblastoma.

    PubMed

    Verneris, Michael R; Wagner, John E

    2007-06-01

    Neuroblastoma (NB) is a common and aggressive tumor of early childhood. To date, treatment with chemotherapy, surgery, and radiation therapy has resulted in suboptimal outcomes in those with advanced disease. Immune-based treatments hold promise for patients with recurrent or advanced NB. Here, recent preclinical studies and early stage (phase I) clinical trials using cellular therapeutic approaches for NB are reviewed, including studies of natural killer cells, gammadelta T cells, chimeric receptor expressing T cells, dendritic cells, and allogeneic hematopoietic cell transplant.

  9. Influence of pH on the quantum-size-controlled photoelectrochemical etching of epitaxial InGaN quantum dots

    DOE PAGES

    Xiao, Xiaoyin; Lu, Ping; Fischer, Arthur J.; Coltrin, Michael E.; Wang, George T.; Koleske, Daniel D.; Tsao, Jeffrey Y.

    2015-11-18

    Illumination by a narrow-band laser has been shown to enable photoelectrochemical (PEC) etching of InGaN thin films into quantum dots with sizes controlled by the laser wavelength. Here, we investigate and elucidate the influence of solution pH on such quantum-size-controlled PEC etch process. We find that although a pH above 5 is often used for PEC etching of GaN-based materials, oxides (In2O3 and/or Ga2O3) form which interfere with quantum dot formation. Furthermore, at pH below 3, however, oxide-free QDs with self-terminated sizes can be successfully realized.

  10. Influence of pH on the quantum-size-controlled photoelectrochemical etching of epitaxial InGaN quantum dots

    SciTech Connect

    Xiao, Xiaoyin; Lu, Ping; Fischer, Arthur J.; Coltrin, Michael E.; Wang, George T.; Koleske, Daniel D.; Tsao, Jeffrey Y.

    2015-11-18

    Illumination by a narrow-band laser has been shown to enable photoelectrochemical (PEC) etching of InGaN thin films into quantum dots with sizes controlled by the laser wavelength. Here, we investigate and elucidate the influence of solution pH on such quantum-size-controlled PEC etch process. We find that although a pH above 5 is often used for PEC etching of GaN-based materials, oxides (In2O3 and/or Ga2O3) form which interfere with quantum dot formation. Furthermore, at pH below 3, however, oxide-free QDs with self-terminated sizes can be successfully realized.

  11. Advancing the Chemistry of CuWO4 for Photoelectrochemical Water Oxidation.

    PubMed

    Lhermitte, Charles R; Bartlett, Bart M

    2016-06-21

    Photoelectrochemical (PEC) cells are an ongoing area of exploration that provide a means of converting solar energy into a storable chemical form (molecular bonds). In particular, using PEC cells to drive the water splitting reaction to obtain H2 could provide a clean and sustainable route to convert solar energy into chemical fuels. Since the discovery of catalytic water splitting on TiO2 photoelectrodes by Fujishima and Honda, significant efforts have been directed toward developing high efficiency metal oxides to use as photocatalysts for this reaction. Improving the efficiency of PEC cells requires developing chemically stable, and highly catalytic anodes for the oxygen-evolution reaction (OER). This water oxidation half reaction requires four protons and four electrons coupling in two bond making steps to form O2, which limits the rate. Our group has accelerated efforts in CuWO4 as a candidate for PEC OER chemistry. Its small band gap of 2.3 eV allows for using visible light to drive OER, and the reaction proceeds with a high degree of chemoselectivity, even in the presence of more kinetically accessible anions such as chloride, which is common to seawater. Furthermore, CuWO4 is a chemically robust material when subjected to the highly oxidizing conditions of PEC OER. The next steps for accelerating research using this (and other), ternary phase oxides, is to move beyond reporting the basic PEC measurements to understanding fundamental chemical reaction mechanisms operative during OER on semiconductor surfaces. In this Account, we outline the process for PEC OER on CuWO4 thin films with emphasis on the chemistry of this reaction, the reaction rate and selectivity (determined by controlled-potential coulometry and oxygen-detection experiments). We discuss key challenges with CuWO4 such as slow kinetics and the presence of an OER-mediating mid-gap state, probed by electrochemical impedance spectroscopy. We propose that this mid-gap state imparts the observed

  12. Advancing the Chemistry of CuWO4 for Photoelectrochemical Water Oxidation.

    PubMed

    Lhermitte, Charles R; Bartlett, Bart M

    2016-06-21

    Photoelectrochemical (PEC) cells are an ongoing area of exploration that provide a means of converting solar energy into a storable chemical form (molecular bonds). In particular, using PEC cells to drive the water splitting reaction to obtain H2 could provide a clean and sustainable route to convert solar energy into chemical fuels. Since the discovery of catalytic water splitting on TiO2 photoelectrodes by Fujishima and Honda, significant efforts have been directed toward developing high efficiency metal oxides to use as photocatalysts for this reaction. Improving the efficiency of PEC cells requires developing chemically stable, and highly catalytic anodes for the oxygen-evolution reaction (OER). This water oxidation half reaction requires four protons and four electrons coupling in two bond making steps to form O2, which limits the rate. Our group has accelerated efforts in CuWO4 as a candidate for PEC OER chemistry. Its small band gap of 2.3 eV allows for using visible light to drive OER, and the reaction proceeds with a high degree of chemoselectivity, even in the presence of more kinetically accessible anions such as chloride, which is common to seawater. Furthermore, CuWO4 is a chemically robust material when subjected to the highly oxidizing conditions of PEC OER. The next steps for accelerating research using this (and other), ternary phase oxides, is to move beyond reporting the basic PEC measurements to understanding fundamental chemical reaction mechanisms operative during OER on semiconductor surfaces. In this Account, we outline the process for PEC OER on CuWO4 thin films with emphasis on the chemistry of this reaction, the reaction rate and selectivity (determined by controlled-potential coulometry and oxygen-detection experiments). We discuss key challenges with CuWO4 such as slow kinetics and the presence of an OER-mediating mid-gap state, probed by electrochemical impedance spectroscopy. We propose that this mid-gap state imparts the observed

  13. Quantum Dot-Based Cell Motility Assay

    SciTech Connect

    Gu, Weiwei; Pellegrino, Teresa; Parak Wolfgang J; Boudreau,Rosanne; Le Gros, Mark A.; Gerion, Daniele; Alivisatos, A. Paul; Larabell, Carolyn A.

    2005-06-06

    Because of their favorable physical and photochemical properties, colloidal CdSe/ZnS-semiconductor nanocrystals (commonly known as quantum dots) have enormous potential for use in biological imaging. In this report, we present an assay that uses quantum dots as markers to quantify cell motility. Cells that are seeded onto a homogeneous layer of quantum dots engulf and absorb the nanocrystals and, as a consequence, leave behind a fluorescence-free trail. By subsequently determining the ratio of cell area to fluorescence-free track area, we show that it is possible to differentiate between invasive and noninvasive cancer cells. Because this assay uses simple fluorescence detection, requires no significant data processing, and can be used in live-cell studies, it has the potential to be a powerful new tool for discriminating between invasive and noninvasive cancer cell lines or for studying cell signaling events involved in migration.

  14. Polypyrrole nanowire-based enzymatic biofuel cells.

    PubMed

    Kim, Jihun; Kim, Sung In; Yoo, Kyung-Hwa

    2009-10-15

    Glucose/O(2) biofuel cells with an improved power density were developed, using polypyrrole (PPy) nanowires containing glucose oxidase and 8-hydroxyquinoline-5-sulfonic acid hydrate as an anode. The PPy nanowire anode was made by electropolymerizing within the nanopores of an anodized aluminum oxide (AAO) template, and then dissolving the AAO template. The nanowire-type biofuel cell exhibited a higher power density than the film-type biofuel cell by two orders of magnitude; this was likely due to an increase in surface area and enzyme loading. Additionally, we constructed a glucose/O(2) biofuel cell covered with a fluidic channel. Biofuel cells with and without a fluidic channel had comparable performance, demonstrating the feasibility of integrated biofuel cells within a fluidic cell.

  15. Research Update: Photoelectrochemical water splitting and photocatalytic hydrogen production using ferrites (MFe2O4) under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Dillert, Ralf; Taffa, Dereje H.; Wark, Michael; Bredow, Thomas; Bahnemann, Detlef W.

    2015-10-01

    The utilization of solar light for the photoelectrochemical and photocatalytic production of molecular hydrogen from water is a scientific and technical challenge. Semiconductors with suitable properties to promote solar-driven water splitting are a desideratum. A hitherto rarely investigated group of semiconductors are ferrites with the empirical formula MFe2O4 and related compounds. This contribution summarizes the published results of the experimental investigations on the photoelectrochemical and photocatalytic properties of these compounds. It will be shown that the potential of this group of compounds in regard to the production of solar hydrogen has not been fully explored yet.

  16. Enhanced Photoelectrochemical Detection of Bioaffinity Reactions by Vertically Oriented Au Nanobranches Complexed with a Biotinylated Polythiophene Derivative

    PubMed Central

    Zhou, Huiqiong; Tang, Yanli; Zhai, Jin; Wang, Shu; Tang, Zhiyong; Jiang, Lei

    2009-01-01

    Four nanostructured Au electrodes were prepared by a simple and templateless electrochemical deposition technique. After complexing with a biotinylated polythiophene derivative (PTBL), photocurrent generation and performance of PTBL/Au-nanostructured electrodes as photoelectrochemical biosensors were investigated. Among these four nanostructured Au electrodes, vertically oriented nanobranches on the electrode significantly improved the photoelectric conversion, because the vertically oriented nanostructures not only benefit light harvesting but also the transfer of the photogenerated charge carriers. Owing to this advantaged nanostructure, the PTBL/Au-nanobranch electrode showed higher sensitivity and faster response times in the photoelectrochemical detection of a streptavidin-biotin affinity reaction compared to a PTBL/Au-nanoparticle electrode. PMID:22399957

  17. Cell-based Assays to Identify Inhibitors of Viral Disease

    PubMed Central

    Green, Neil; Ott, Robert D.; Isaacs, Richard J.; Fang, Hong

    2009-01-01

    Background Antagonizing the production of infectious virus inside cells requires drugs that can cross the cell membrane without harming host cells. Objective It is therefore advantageous to establish intracellular potency of anti-viral drug candidates early in the drug-discovery pipeline. Methods To this end, cell-based assays are being developed and employed in high-throughput drug screening, ranging from assays that monitor replication of intact viruses to those that monitor activity of specific viral proteins. While numerous cell-based assays have been developed and investigated, rapid counter screens are also needed to define the specific viral targets of identified inhibitors and to eliminate nonspecific screening hits. Results/Conclusions Here, we describe the types of cell-based assays being used in antiviral drug screens and evaluate the equally important counter screens that are being employed to reach the full potential of cell-based high-throughput screening. PMID:19750206

  18. Stromal cell-based immunotherapy in transplantation

    PubMed Central

    Charles, Ronald; Lu, Lina; Qian, Shiguang; Fung, John J

    2012-01-01

    Organs are composed of parenchymal cells that characterize organ function and nonparenchymal cells that are composed of cells in transit, as well as tissue connective tissue, also referred to as tissue stromal cells. It was originally thought that these tissue stromal cells provided only structural and functional support for parenchymal cells and were relatively inert. However, we have come to realize that tissue stromal cells, not restricted to in the thymus and lymphoid organs, also play an active role in modulating the immune system and its response to antigens. The recognition of these elements and the elucidation of their mechanisms of action have provided valuable insight into peripheral immune regulation. Extrapolation of these principles may allow us to utilize their potential for clinical application. In this article, we will summarize a number of tissue stromal elements/cell types that have been shown to induce hyporesponsiveness to transplants. We will also discuss the mechanisms by which these stromal cells create a tolerogenic environment, which in turn results in long-term allograft survival. PMID:22091683

  19. Cell-based treatments for diabetes.

    PubMed

    Jones, Peter M; Courtney, Monica L; Burns, Christopher J; Persaud, Shanta J

    2008-10-01

    In Type 1 diabetes mellitus the insulin-secreting beta-cells in pancreatic islets of Langerhans are selectively destroyed by autoimmune assault. Because diabetes is caused by the loss of a single cell type it is amenable to treatment by cell replacement therapy. Advances in islet transplantation procedures have demonstrated that people with Type 1 diabetes can be cured by human islet transplantation, but the severely limited availability of donor islets has restricted the widespread application of this approach, and driven the search for substitute transplant tissues. Recent experimental studies suggest that three separate sources of tissue show therapeutic potential--xenografts from other species, tissue stem cells and embryonic stem cells. Of these, xenografts are closest to clinical application but there are still major obstacles to be overcome. Insulin-expressing cells have been derived from a number of different stem cell populations but embryonic stem cells offer the major advantage of being able, in principle, to provide the vast numbers of cells required for transplantation therapy. PMID:18652911

  20. Photoelectrochemical and physical properties of tungsten trioxide films obtained by aerosol pyrolysis

    SciTech Connect

    Sadale, S.B.; Chaqour, S.M.; Gorochov, O.; Neumann-Spallart, M.

    2008-06-03

    Aerosol pyrolysis (AP) was used for preparing semiconducting films of tungsten trioxide using peroxotungstic acid as a precursor. The films were characterized by SEM, XRD, and by their photoelectrochemical response. Porous, polycrystalline (monoclinic) films of thickness up to 3 {mu}m were prepared. An incident photon to current efficiency (IPCE) of 0.55 at 365 nm was obtained for films of 1 {mu}m thickness on conducting F:SnO{sub 2}/glass substrates under depletion conditions, in junctions with aqueous electrolytes. The spectral (photocurrent) response extended into the visible region (up to 470 nm) which is of importance for solar applications like photocatalysis.

  1. Enhanced Photoelectrochemical Oxygen Evolution Reaction Ability of Iron-Derived Hematite Photoanode with Titanium Modification.

    PubMed

    Qiu, Weitao; Huang, Yongchao; Long, Bei; Li, Haibo; Tong, Yexiang; Ji, Hongbing

    2015-12-21

    A facile fabrication route towards a titanium-modified hematite photoanode has been developed, and the photoelectrochemical properties of this anode have been evaluated. Compared to pristine hematite, the activity of the modified photoanode in this work delivered almost twofold higher photocurrent under Air Mass 1.5G illumination. Further research revealed that the enhanced performance of the hematite photoanode with a titanium-modified surface resulted from the dominant impact of heterojunction formation and suppressed surface recombination, supplemented by a slightly improved light-harnessing ability. PMID:26558337

  2. Photoelectrochemical protection of stainless alloys from the stress-corrosion cracking in BWR primary coolant environment

    SciTech Connect

    Akashi, Masatsune; Iso-o, Hiroyuki; Kubota, Nobuhiko; Fukuda, Takanori; Ayabe, Muneo; Hirano, Kenji

    1995-12-31

    The feasibility of counteracting or preventing the stress-corrosion cracking in the BWR core internals by the photoelectrochemical method has been examined. For the purpose TiO{sub 2} semiconductor is noted for its capability of photo electrochemically inducing the water-oxidizing anodic reaction in low enough potential domain if supplied with a light of a wavelength shorter than 410 nm. This paper offers an empirical proof by showing that Type 304 stainless steel and Alloy 600 stainless alloy that have been plasma-spray coated with TiO{sub 2} film will do quite well in environments of BWR primary coolant.

  3. Silicon nanostructures-induced photoelectrochemical solar water splitting for energy applications

    NASA Astrophysics Data System (ADS)

    Dadwal, U.; Ranjan, Neha; Singh, R.

    2016-05-01

    We study the photoelectrochemical (PEC) solar water splitting assisted with synthesized nanostructures. Si nanowires decorated with silver dendrite nanostructures have been synthesized using metal assisted wet chemical etching of (100) Si wafer. Etching has been carried out in an aqueous solution consisting of 5M HF and 0.02M AgNO3. Investigations showed that such type of semiconductor nanostructures act as efficient working electrodes for the splitting of normal water in PEC method. An enhancement in the photon-to-current conversion efficiency and solar-to-hydrogen evolution was observed for obtaining a practical source of clean and renewable fuel.

  4. Research Update: Strategies for efficient photoelectrochemical water splitting using metal oxide photoanodes

    SciTech Connect

    Cho, Seungho; Jang, Ji-Wook; Lee, Kun-Hong E-mail: ce20047@postech.ac.kr; Lee, Jae Sung E-mail: ce20047@postech.ac.kr

    2014-01-01

    Photoelectrochemical (PEC) water splitting to hydrogen is an attractive method for capturing and storing the solar energy in the form of chemical energy. Metal oxides are promising photoanode materials due to their low-cost synthetic routes and higher stability than other semiconductors. In this paper, we provide an overview of recent efforts to improve PEC efficiencies via applying a variety of fabrication strategies to metal oxide photoanodes including (i) size and morphology-control, (ii) metal oxide heterostructuring, (iii) dopant incorporation, (iv) attachments of quantum dots as sensitizer, (v) attachments of plasmonic metal nanoparticles, and (vi) co-catalyst coupling. Each strategy highlights the underlying principles and mechanisms for the performance enhancements.

  5. Photoelectrochemical deoxyribonucleic acid sensing on a nanostructured TiO2 electrode

    NASA Astrophysics Data System (ADS)

    Tokudome, Hiromasa; Yamada, Yoko; Sonezaki, Shuji; Ishikawa, Hiroshi; Bekki, Makoto; Kanehira, Koki; Miyauchi, Masahiro

    2005-11-01

    A nanostructured TiO2 electrode chemisorbed with probe deoxyribonucleic acid (DNA) can photoelectrochemically detect a dye-labeled target DNA molecule. After the hybridization between the probe and target DNA molecules, light irradiation generates electrons in the dye molecules, and these electrons are injected into the TiO2 electrode. The resulting photocurrent can be measured and corresponds to the concentration of target DNA. This sensor can quantitatively detect target DNA at lower than nanomolar concentrations. In addition, by utilizing two different dyes, different DNA sequences can be detected on the TiO2 electrode.

  6. Exposure of WO3 Photoanodes to Ultraviolet Light Enhances Photoelectrochemical Water Oxidation.

    PubMed

    Li, Tengfei; He, Jingfu; Peña, Bruno; Berlinguette, Curtis P

    2016-09-28

    Exposure of WO3 photoanodes to sustained irradiation by ultraviolet (UV) light induces a morphology change that enhances the photoelectrochemical (PEC) activity towards the oxygen evolution reaction (OER). A 30% enhancement in photocurrent density at 1.23 V vs RHE was measured despite a nominal change in onset potential. A structural and electrochemical analysis of the films before and after exposure to UV irradiation indicates that a higher film porosity and correspondingly higher specific surface area is responsible for the enhancement in PEC activity. The effect of prolonged UV irradiation on the WO3 films is fundamentally different to that which was previously observed for BiVO4 films.

  7. Exposure of WO3 Photoanodes to Ultraviolet Light Enhances Photoelectrochemical Water Oxidation.

    PubMed

    Li, Tengfei; He, Jingfu; Peña, Bruno; Berlinguette, Curtis P

    2016-09-28

    Exposure of WO3 photoanodes to sustained irradiation by ultraviolet (UV) light induces a morphology change that enhances the photoelectrochemical (PEC) activity towards the oxygen evolution reaction (OER). A 30% enhancement in photocurrent density at 1.23 V vs RHE was measured despite a nominal change in onset potential. A structural and electrochemical analysis of the films before and after exposure to UV irradiation indicates that a higher film porosity and correspondingly higher specific surface area is responsible for the enhancement in PEC activity. The effect of prolonged UV irradiation on the WO3 films is fundamentally different to that which was previously observed for BiVO4 films. PMID:27644107

  8. Silicon Micropore based Electromechanical Transducer to Differentiate Tumor Cells

    NASA Astrophysics Data System (ADS)

    Ali, Waqas; Raza, Muhammad U.; Khanzada, Raja R.; Kim, Young-Tae; Iqbal, Samir M.

    2015-03-01

    Solid-state micropores have been used before to differentiate cancer cells from normal cells using size-based filtering. Tumor cells differ from normal ones not only in size but also in physical properties like elasticity, shape, motility etc. Tumor cells show different physical attributes depending on the stage and type of cancer. We report a micropore based electromechanical transducer that differentiated cancer cells based on their mechanophysical properties. The device was interfaced with a high-speed patch-clamp measurement system that biased the ionic solution across the silicon-based membrane. The bias resulted in the flow of ionic current. Electrical pulses were generated when cells passed through. Different cells depicted characteristic pulses. Translocation profiles of cells that were either small or were more elastic and flexible caused electrical pulses shorter in widths and amplitudes whereas cells with larger size or lesser elasticity/flexibility showed deeper and wider pulses. Three non-small cell lung cancer (NSCLC) cell lines NCI-H1155, A549 and NCI-H460 were successfully differentiated. NCI-H1155, due to their comparatively smaller size, were found quickest in translocating through. The solid-sate micropore based electromechanical transducer could process the whole blood sample of cancer patient without any pre-processing requirements and is ideal for point-of-care applications. Support Acknowledged from NSF through ECCS-1201878.

  9. Non-genetic engineering of cells for drug delivery and cell-based therapy.

    PubMed

    Wang, Qun; Cheng, Hao; Peng, Haisheng; Zhou, Hao; Li, Peter Y; Langer, Robert

    2015-08-30

    Cell-based therapy is a promising modality to address many unmet medical needs. In addition to genetic engineering, material-based, biochemical, and physical science-based approaches have emerged as novel approaches to modify cells. Non-genetic engineering of cells has been applied in delivering therapeutics to tissues, homing of cells to the bone marrow or inflammatory tissues, cancer imaging, immunotherapy, and remotely controlling cellular functions. This new strategy has unique advantages in disease therapy and is complementary to existing gene-based cell engineering approaches. A better understanding of cellular systems and different engineering methods will allow us to better exploit engineered cells in biomedicine. Here, we review non-genetic cell engineering techniques and applications of engineered cells, discuss the pros and cons of different methods, and provide our perspectives on future research directions.

  10. Label-free density difference amplification-based cell sorting.

    PubMed

    Song, Jihwan; Song, Minsun; Kang, Taewook; Kim, Dongchoul; Lee, Luke P

    2014-11-01

    The selective cell separation is a critical step in fundamental life sciences, translational medicine, biotechnology, and energy harvesting. Conventional cell separation methods are fluorescent activated cell sorting and magnetic-activated cell sorting based on fluorescent probes and magnetic particles on cell surfaces. Label-free cell separation methods such as Raman-activated cell sorting, electro-physiologically activated cell sorting, dielectric-activated cell sorting, or inertial microfluidic cell sorting are, however, limited when separating cells of the same kind or cells with similar sizes and dielectric properties, as well as similar electrophysiological phenotypes. Here we report a label-free density difference amplification-based cell sorting (dDACS) without using any external optical, magnetic, electrical forces, or fluidic activations. The conceptual microfluidic design consists of an inlet, hydraulic jump cavity, and multiple outlets. Incoming particles experience gravity, buoyancy, and drag forces in the separation chamber. The height and distance that each particle can reach in the chamber are different and depend on its density, thus allowing for the separation of particles into multiple outlets. The separation behavior of the particles, based on the ratio of the channel heights of the inlet and chamber and Reynolds number has been systematically studied. Numerical simulation reveals that the difference between the heights of only lighter particles with densities close to that of water increases with increasing the ratio of the channel heights, while decreasing Reynolds number can amplify the difference in the heights between the particles considered irrespective of their densities. PMID:25553185

  11. Aerosol-Based Cell Therapy for Treatment of Lung Diseases.

    PubMed

    Kardia, Egi; Halim, Nur Shuhaidatul Sarmiza Abdul; Yahaya, Badrul Hisham

    2016-01-01

    Aerosol-based cell delivery technique via intratracheal is an effective route for delivering transplant cells directly into the lungs. An aerosol device known as the MicroSprayer(®) Aerosolizer is invented to transform liquid into an aerosol form, which then can be applied via intratracheal administration for drug delivery. The device produces a uniform and concentrated distribution of aerosolized liquid. Using the capability of MicroSprayer(®) Aerosolizer to transform liquid into aerosol form, our group has designed a novel method of cell delivery using an aerosol-based technique. We have successfully delivered skin-derived fibroblast cells and airway epithelial cells into the airway of a rabbit with minimum risk of cell loss and have uniformly distributed the cells into the airway. This chapter illustrates the application of aerosol device to deliver any type of cells for future treatment of lung diseases. PMID:27062596

  12. Heart-on-a-chip based on stem cell biology.

    PubMed

    Jastrzebska, Elzbieta; Tomecka, Ewelina; Jesion, Iwona

    2016-01-15

    Heart diseases are one of the main causes of death around the world. The great challenge for scientists is to develop new therapeutic methods for these types of ailments. Stem cells (SCs) therapy could be one of a promising technique used for renewal of cardiac cells and treatment of heart diseases. Conventional in vitro techniques utilized for investigation of heart regeneration do not mimic natural cardiac physiology. Lab-on-a-chip systems may be the solution which could allow the creation of a heart muscle model, enabling the growth of cardiac cells in conditions similar to in vivo conditions. Microsystems can be also used for differentiation of stem cells into heart cells, successfully. It will help better understand of proliferation and regeneration ability of these cells. In this review, we present Heart-on-a-chip systems based on cardiac cell culture and stem cell biology. This review begins with the description of the physiological environment and the functions of the heart. Next, we shortly described conventional techniques of stem cells differentiation into the cardiac cells. This review is mostly focused on describing Lab-on-a-chip systems for cardiac tissue engineering. Therefore, in the next part of this article, the microsystems for both cardiac cell culture and SCs differentiation into cardiac cells are described. The section about SCs differentiation into the heart cells is divided in sections describing biochemical, physical and mechanical stimulations. Finally, we outline present challenges and future research concerning Heart-on-a-chip based on stem cell biology.

  13. Single-cell Genomics using Droplet-based Microfluidics

    NASA Astrophysics Data System (ADS)

    Basu, Anindita; Macosko, Evan; Shalek, Alex; McCarroll, Steven; Regev, Aviv; Weitz, Dave

    2014-03-01

    We develop a system to profile the transcriptome of mammalian cells in isolation using reverse emulsion droplet-based microfluidic techniques. This is accomplished by (a) encapsulating and lysing one cell per emulsion droplet, and (b) uniquely barcoding the RNA contents from each cell using unique DNA-barcoded microgel beads. This enables us to study the transcriptional behavior of a large number of cells at single-cell resolution. We then use these techniques to study transcriptional responses of isolated immune cells to precisely controlled chemical and pathological stimuli provided in the emulsion droplet.

  14. Biomagnetics and Cell-Based Biochips

    NASA Astrophysics Data System (ADS)

    Ingber, Donald

    2005-03-01

    This presentation will review various micro- and nanotechnologies that we have developed over the past decade in our efforts to manipulate and probe living cells. In early studies, we used magnetic micro-particles to apply controlled mechanical forces to surface membrane receptors. We did this to probe cellular mechanical properties, and to investigate the molecular basis of mechanotransduction -- how mechanical forces are transduced into changes in intracellular biochemistry. The magnetic beads were coated with ligands for adhesion receptors, such as synthetic RGD (arginine-glycine-aspartate) peptides or antibodies that bind to membrane integrin receptors. Controlled twisting (torque) or pulling (tension) forces were exerted on the integrin-bound beads using magnetic twisting or pulling cytometry. To investigate the cellular response to dynamic forces, and to increase the level of stress applied, an electromagnetic needle was developed to apply a temporally varying magnetic field controlled by a user-defined solenoidal current; the end of the needle also was electropolished to produce a nanoscale pole tip. Magnetic forces applied to integrin receptors, but not other cell-surface receptors, induced force-dependent recruitment of cytoskeletal linker (focal adhesion) proteins to the site of bead binding, resulting in assembly and mechanical strengthening of the adhesions. Stress application to integrins also resulted in force-dependent increases in cAMP signaling and induction of gene transcription. These experiments revealed that integrins and the cytoskeleton play a central role in cellular mechanotransduction.studies in collaboration with George Whitesides (Harvard U.), we used microcontact printing techniques with self- assembled monolayers of alkanethiols to microfabricate extracellular matrix-coated adhesive islands of defined size, shape, and position on the micrometer scale. When cells were plated on these islands, the spread to take on the form of the island

  15. All solid-state solar cells based on CH3NH3PbI3-sensitized TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Yang, Xiuchun; Liu, Wei; Ren, Peng

    2016-09-01

    TiO2 nanotube arrays (TiO2 NTAs) were firstly used as photoanode in methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2 NTAs heterojunction solar cell, where CH3NH3PbI3 functions as both light absorber and hole conductor. The composition, structure and photoelectrochemical properties of the as-prepared samples were characterized by x-ray diffractometer (XRD), field-emission scanning electron microscope (FE-SEM), ultraviolet-visible (UV-vis) spectrophotometer and electrochemical workstation. The results indicate that the as-prepared CH3NH3PbI3 belongs to the cubic crystal system, and TiO2 NTAs sensitized by 0.3 M CH3NH3I and PbI2 exhibit the best photoelectrochemical properties with an open-circuit voltage of 0.422 V and a short-circuit current density of 173.4 μA cm-2. The EIS result shows that the extremely large resistance at CH3NH3PbI3/FTO interface contributes to the low current density of the perovskite solar cell.

  16. Intuitive, Image-Based Cell Sorting Using Opto-fluidic Cell Sorting

    PubMed Central

    Kovac, J. R.; Voldman, J.

    2008-01-01

    We present a microfluidic cell sorting device which augments microscopy with the capability to perform facile image-based cell sorting. This combination enables intuitive, complex phenotype sorting based on spatio-temporal fluorescence or cell morphology. The microfluidic device contains a microwell array that can be passively loaded with mammalian cells via sedimentation and can be subsequently inspected with microscopy. After inspection, we use the scattering force from a focused infrared laser to levitate cells of interest from their wells into a flow field for collection. First, we demonstrate image-based sorting predicated on whole-cell fluorescence, which could enable sorting based on temporal whole-cell fluorescence behavior. Second, we demonstrate image-based sorting predicated on fluorescence localization (nuclear vs. whole-cell fluorescence), highlighting the capability of our approach to sort based on imaged sub-cellular events, such as localized protein expression or translocation events. We achieve post-sort purities up to 89%, and up to 155-fold enrichment of target cells. Optical manipulation literature and a direct cell viability assay suggest that cells remain viable after using our technique. The architecture is highly scalable and supports over 10,000 individually addressable trap sites. Our approach enables sorting of significant populations based on sub-cellular spatio-temporal information, which is difficult or impossible with existing widespread sorting technologies. PMID:18004819

  17. Cell-based gene therapy against HIV.

    PubMed

    Dey, R; Pillai, B

    2015-11-01

    The ability to integrate inside the host genome lays a strong foundation for HIV to play hide and seek with the host's immune surveillance mechanisms. Present anti-viral therapies, although successful in suppressing the virus to a certain level, fail to wipe it out completely. However, recent approaches in modifying stem cells and enabling them to give rise to potent/resistant T-cells against HIV holds immense hope for eradication of the virus from the host. In this review, we will briefly discuss previous landmark studies on engineering stem cells or T-cells that have been explored for therapeutic efficacy against HIV. We will also analyze potential benefits and pitfalls of some studies done recently and will share our opinion on emerging trends.

  18. Importance of the stem cell microenvironment for ophthalmological cell-based therapy

    PubMed Central

    Wan, Peng-Xia; Wang, Bo-Wen; Wang, Zhi-Chong

    2015-01-01

    large number of studies suggest that to explore how to reconstruct the stem cell microenvironment and strengthen its combination with the transplanted cells are key steps to successful cell therapy. In this review, we will describe the interactions of the stem cell microenvironment with the stem cells, discuss the importance of the stem cell microenvironment for cell-based therapy in ocular diseases, and introduce the progress of stem cell-based therapy for ocular diseases. PMID:25815128

  19. Photoelectrochemical properties and the detection mechanism of Bi2WO6 nanosheet modified TiO2 nanotube arrays.

    PubMed

    Pang, Yajun; Xu, Guangqing; Zhang, Xu; Lv, Jun; Shi, Kai; Zhai, Pengbo; Xue, Qianyun; Wang, Xuedong; Wu, Yucheng

    2015-10-28

    Bi2WO6 nanosheet modified TiO2 nanotube arrays were synthesized by an anodization method combined with sequential chemical bath deposition for enhancement of the photoelectrochemical detection performance. The structures, morphologies and elemental compositions of the nanotube arrays were characterized with X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectrometry. Bi2WO6 nanosheets were successfully deposited on the tube walls of TiO2 nanotubes. The photoelectrochemical property of Bi2WO6/TiO2 NTAs was determined with chronoamperometry and cyclic voltammetry using an electrochemical workstation equipped with a UV LED light (365 nm). The optimum detection sensitivity of glucose in water was determined to be 0.244 μA mM(-1) in the linear range from 0 to 2500 μM. Bi2WO6 modification on TiO2 NTAs simultaneously decreased the background photocurrent and increased the current response to organics, resulting in the enhancement of photoelectrochemical detection properties. Mechanisms of the Bi2WO6 modification are discussed by analyzing the photoelectrochemical processes, including optical absorption, charges transfer and surface electrochemical reactions. Direct oxidation by holes rather than indirect oxidation by ˙OH radicals is believed to be a key role in this enhancement.

  20. Hydrogels and Cell Based Therapies in Spinal Cord Injury Regeneration

    PubMed Central

    Assunção-Silva, Rita C.; Gomes, Eduardo D.; Silva, Nuno A.; Salgado, António J.

    2015-01-01

    Spinal cord injury (SCI) is a central nervous system- (CNS-) related disorder for which there is yet no successful treatment. Within the past several years, cell-based therapies have been explored for SCI repair, including the use of pluripotent human stem cells, and a number of adult-derived stem and mature cells such as mesenchymal stem cells, olfactory ensheathing cells, and Schwann cells. Although promising, cell transplantation is often overturned by the poor cell survival in the treatment of spinal cord injuries. Alternatively, the therapeutic role of different cells has been used in tissue engineering approaches by engrafting cells with biomaterials. The latter have the advantages of physically mimicking the CNS tissue, while promoting a more permissive environment for cell survival, growth, and differentiation. The roles of both cell- and biomaterial-based therapies as single therapeutic approaches for SCI repair will be discussed in this review. Moreover, as the multifactorial inhibitory environment of a SCI suggests that combinatorial approaches would be more effective, the importance of using biomaterials as cell carriers will be herein highlighted, as well as the recent advances and achievements of these promising tools for neural tissue regeneration. PMID:26124844