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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. PMID:17299626

  2. Photosystem I - based biohybrid photoelectrochemical cells.

    PubMed

    Ciesielski, Peter N; Hijazi, Frederick M; Scott, Amanda M; Faulkner, Christopher J; Beard, Lisa; Emmett, Kevin; Rosenthal, Sandra J; Cliffel, David; Kane Jennings, G

    2010-05-01

    Photosynthesis is the process by which Nature coordinates a tandem of protein complexes of impressive complexity that function to harness staggering amounts of solar energy on a global scale. Advances in biochemistry and nanotechnology have provided tools to isolate and manipulate the individual components of this process, thus opening a door to a new class of highly functional and vastly abundant biological resources. Here we show how one of these components, Photosystem I (PSI), is incorporated into an electrochemical system to yield a stand-alone biohybrid photoelectrochemical cell that converts light energy into electrical energy. The cells make use of a dense multilayer of PSI complexes assembled on the surface of the cathode to produce a photocatalytic effect that generates photocurrent densities of approximately 2 microA/cm(2) at moderate light intensities. We describe the relationship between the current and voltage production of the cells and the photoinduced interactions of PSI complexes with electrochemical mediators, and show that the performance of the present device is limited by diffusional transport of the electrochemical mediators through the electrolyte. These biohybrid devices display remarkable stability, as they remain active in ambient conditions for at least 280 days. Even at bench-scale production, the materials required to fabricate the cells described in this manuscript cost approximately 10 cents per cm(2) of active electrode area. PMID:20064713

  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. Bacteriorhodopsin-based photo-electrochemical cell.

    PubMed

    Chu, Li-Kang; Yen, Chun-Wan; El-Sayed, Mostafa A

    2010-10-15

    A simple solution-based electrochemical cell has been constructed and successfully employed in the detection of the photoelectric response upon photoexcitation of bacteriorhodopsin (bR) without external bias. Commercially-available indium tin oxide (ITO) glasses served as the optical windows and electrodes. Small amounts of bR suspensions (∼100 μL) were utilized as the photovoltaic medium to generate the proton gradient between two half-cells separated by a molecular porous membrane. Continuous broadband visible light (λ>380 nm) and a short-pulse 532-nm laser were employed for the photoexcitation of bR. Upon the modulated cw broadband irradiation, an instantaneous rise and decay of the current was observed. Our observations of the pH-dependent photocurrent are consistent with previous reports in a bR thin film configuration, which also showed a polarity inversion at pH 5-6. This is due to the change of the priority of the proton release and proton uptake in the photocycle of bR. Studies on the ionic strength effect were also carried out at different KCl concentrations, which resulted in the acceleration of the rise and decay of the photoelectric response. This was accompanied by a decrease in the stationary photocurrent at higher KCl concentrations in the broadband excitation experiments. The solution-based electrochemical cell uses aqueous medium, which is required for the completion of the bR proton pumping function. Due to the generation of the stationary current, it is advantageous to convert solar energy into electricity without the need of film-based photovoltaic devices with external bias. PMID:20719494

  6. 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…

  7. Improved performance of InSe-based photoelectrochemical cells by means of a selective (photo)electrochemical etching

    NASA Astrophysics Data System (ADS)

    Tenne, R.; Theys, B.; Rioux, J.; Levy-Clement, C.

    1985-01-01

    It is shown that the performance of photoelectrochemical cells based on the lamellar material InSe can be considerably improved by means of a selective (photo)electrochemical etching. Whereas the cleavage Van de Waals plane (⊥ to c axis) shows little improvement, the photcurrent in the ∥ face (parallel to the c axis) is doubled (30 mA cm-2 under AM1 illumination). For n-type InSe a reverse bias (+1.5 V versus standard calomel electrode SCE) was employed during the photoetching, p-InSe electrodes were electrochemically etched by applying a forward bias (+1.5 V). In both cases, surface holes carry out the selective corrosion of the semiconductor surface which is another manifestation for the asymmetry played by holes and electrons on semiconductor surfaces. It is hoped that this finding will pave the way for the construction of high-efficiency solar cells based on a thin film made of lamellar materials.

  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. A photoelectrochemical methanol fuel cell based on aligned TiO2 nanorods decorated graphene photoanode.

    PubMed

    Li, Xinyuan; Wang, Guowen; Jing, Lin; Ni, Wei; Yan, Huan; Chen, Chao; Yan, Yi-Ming

    2016-02-11

    We report the photoelectrochemical (PEC) oxidation of methanol on a rationally designed graphene-TiO2 nanorod array (G-TNR) photoanode. A PEC methanol fuel cell was constructed by coupling the G-TNR photoanode with a cathode. This study raises a conceptual fuel cell that realizes the synergistic energy conversion of chemical energy and solar energy. PMID:26741738

  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. Sunlight-assisted, biocatalytic formate synthesis from CO2 and water using silicon-based photoelectrochemical cells.

    PubMed

    Son, Eun Jin; Ko, Jong Wan; Kuk, Su Keun; Choe, Hyunjun; Lee, Sumi; Kim, Jae Hong; Nam, Dong Heon; Ryu, Gyeong Min; Kim, Yong Hwan; Park, Chan Beum

    2016-08-11

    We report on a silicon-based photoelectrochemical cell that integrates a formate dehydrogenase from Thiobacillus sp. (TsFDH) to convert CO2 to formate using water as an electron donor under visible light irradiation and an applied bias. Our current study suggests that the deliberate integration of biocatalysis to a light-harvesting platform could provide an opportunity to synthesize valuable chemicals with the use of earth-abundant materials and sustainable resources. PMID:27411734

  13. 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.

  14. 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.

  15. 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.

  16. Solar energy conversion by chloroplast photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Bhardwaj, R.; Pan, R. L.; Gross, E. L.

    1981-01-01

    A photoelectrochemical cell based on chloroplasts which generates large photovoltages and photocurrents from solar energy is presented. The cell contains broken Type C chloroplasts placed on a filter separating compartments containing an electron acceptor and electron donor with platinum electrodes in each. Photovoltages were observed across a load resistance of 3000 ohms with either flavin mononucleotide or anthroquinone 2-sulphonate as the electron acceptor and dichlorophenol indophenol as the donor, and persisted for 1-2 hr after the light was turned off. The powers and short circuit currents obtained in the chloroplast cells are nearly equal to those obtained in cells based on isolated photosystem I particles. Finally, an efficiency of 2.3% has been measured for the chloroplast contribution to the total power in flavin mononucleotide cells.

  17. 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

  18. 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.

  19. Construction of flexible photoelectrochemical solar cells based on ordered nanostructural BiOI/Bi2S3 heterojunction films.

    PubMed

    Fang, Mingqing; Jia, Huimin; He, Weiwei; Lei, Yan; Zhang, Lizhi; Zheng, Zhi

    2015-05-28

    Ordered 2D nanostructural BiOI nanoflake arrays decorated with Bi2S3 nanospheres have been designed and in situ fabricated for the first time, to form BiOI/Bi2S3 bulk heterojunctions through a soft chemical route. A modified successive ionic layer adsorption and reaction (SILAR) method was developed to fabricate BiOI nanoflake arrays on flexible ITO/PET substrates at room temperature. The degree of transformation of BiOI to Bi2S3 was controlled through the adjustment of exposure time of the BiOI/ITO substrate to thioacetamide (TAA) aqueous solution. The morphologies of BiOI, BiOI/Bi2S3 heterojunctions and Bi2S3 films were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) patterns, and high resolution transmission electron microscopy (HRTEM). The presence of Bi2S3 was further validated through Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Especially, photoelectrochemical measurements demonstrated that such a Bi2S3 decorated BiOI photoanode based cell exhibits significant augments of short-circuit current density (Jsc) and incident photon-to-current conversion efficiency (IPCE, 3 times higher than the pure BiOI photoanode), attributable to the stronger photo-absorption and better photogenerated charge carrier separation and transport efficiency. The surface photovoltage (SPV) measurements further confirmed the importance of BiOI/Bi2S3 heterojunctions in such PEC cells. This solution-based process directly on flexible ITO offers the promise for low-cost, large-area, roll-to-roll application of the manufacturing of the third generation thin-film photovoltaic devices. PMID:25941684

  20. Photoelectrochemical cell with nondissolving anode

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    Improved electrolytic cells have efficiencies comparable to those of best silicon solar cells but are potentially less expensive to manufacture. Cells consist of light-sensitive n-type semiconductor anode and metallic cathode immersed in electrolytic solution. Reversible redox cells produce no chemical change in electrolyte and stabilize anode against dissolving. Cell can produce more than 500 mW of power per square centimeter of anode area at output voltage of 0.4 V.

  1. A photoelectrochemical sensor based on CdS-polyamidoamine nano-composite film for cell capture and detection.

    PubMed

    Qian, Zheng; Bai, Hai-Jing; Wang, Guang-Li; Xu, Jing-Juan; Chen, Hong-Yuan

    2010-05-15

    We demonstrated herein a newly developed photoelectrochemical cell-sensor for the determination of SMMC-7721 human hepatoma carcinoma cells (SMMC-7721 cells) by using a photosensitive CdS-polyamidoamine (G4) nano-composite film (CdS-PAMAM). The film was generated by electrodeposition method. The presence of PAMAM in the film eliminated the surface defects of CdS nanoparticles and therefore resulted in a greatly enhanced photocurrent and a reduced dark current. In the presence of the electron donor ascorbic acid (AA), the photoexcitation of this modified electrode potentiostated at 0 V versus Ag/AgCl led to an anodic photocurrent. As a result of the covalent coupling reactions, a layer of concanavalin A (ConA) was firmly bound to the functionalized CdS-PAMAM film via glutaraldehyde bridges. The resulting modified electrodes were tested as sensors for SMMC-7721 cell capture and detection via affinity interactions between ConA and mannosyl groups on cell surface. The cell concentration was measured from 5.0 x 10(3) to 1.0 x 10(7) cells mL(-1) through the decrease in photocurrent intensity resulting from its specific binding onto the photosensitive film, the detection limit being 5.0 x 10(3) cells mL(-1). PMID:20181470

  2. ZnO Nanocoral Structures for Photoelectrochemical Cells

    SciTech Connect

    Ahn, K. S.; Yan, Y.; Shet, S.; Jones, K.; Deutsch, T.; Turner, J.; Al-Jassim, M.

    2008-01-01

    We report on synthesis of a uniform and large area of a new form of ZnO nanocorals. These nanostructures can provide suitable electrical pathways for efficient carrier collection as well as large surface areas for the photoelectrochemical (PEC) cells. PEC devices made from these ZnO nanocoral structures demonstrate significantly enhanced photoresponse as compared to ZnO compact and nanorod films. Our results suggest that the nanocoral structures could be an excellent choice for nanomaterial-based applications such as dye-sensitized solar cells, electrochromic windows, and batteries.

  3. Photoelectrochemical cells based on ternary compounds CuIn{sub 2n+1}Se{sub 3n+2} (n = 3-6)

    SciTech Connect

    Rud, V. Yu. Rud, Yu. V.; Bodnar, I. V.; Gorbachev, D. V.; Ushakova, T. N.

    2009-03-15

    Single crystals of ternary CuIn{sub 2n+1}Se{sub 3n+2} semiconductors with the composition index n = 3, 5, 6 were grown for the first time using the direct crystallization method. It was shown that these crystals have hexagonal symmetry and close unit cell parameters. Photoelectrochemical cells based on CuIn{sub 2n+1}Se{sub 3n+2} and In{sub 2}Se{sub 3} single crystals were fabricated. Their photosensitivity spectra were measured for the first time, which were used to determine the nature of interband transitions and the band gap. The weak dependence of the parameters of the band's spectrum and unit cell of these semiconductors at n {>=} 2 was attributed to the features of the interatomic interaction in such phases. It was concluded that new CuIn{sub 2n+1}Se{sub 3n+2} semiconductors can be used in broadband photoconverters of optical radiations.

  4. 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. PMID:23009071

  5. Studies of photocorrosion and passivation of n-GaAs based semiconductor/liquid junction photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Miller, Eric Alan

    Semiconductor photoelectrochemical cells offer a cheap, easily constructed alternative to all-solid-state solar cells. However, a persistent problem in their development has been photocorrosion of the semiconductor electrode. Photocorrosion degrades the electrode, reducing the device lifetime to unacceptably short times. Much effort has gone into developing passivation schemes to reduce or eliminate photocorrosion. None has yet provided permanent protection. A better understanding of the basic interfacial chemistry and physics is necessary to achieve this. Toward this end, the studies described in this manuscript have been performed. n-GaAs has been chosen as the electrode material in these studies due to its strong absorption near a maximum in the solar spectrum. Its photoelectrochemical behavior in Nasb2S has been examined because of the known ability of Nasb2S to passivate photocorrosion. Although the protection provided by Nasb2S is known to be temporary, the focus of these studies is to gain a more complete understanding of the interactions between Nasb2S and GaAs which lead to passivation and photocorrosion. Three separate studies are described in this manuscript. In the first, time-resolved photoluminescence experiments were employed to determine whether the minority carrier surface recombination velocity (SRV) is dependent upon electrolyte concentration. The results indicate that, within the concentration range studied, the SRV is independent of Nasb2S concentration, suggesting that there is no significant change in the degree of semiconductor/electrolyte bond formation. In the second study, the dependence of photocorrosion and passivation on crystallographic orientation was examined. Results show that the (100) and (110) surfaces of GaAs were passivated equally well by Nasb2S, although surface states which eventually formed at the two surfaces were separated in energy by 300 meV. The (111)B surface was not passivated by Nasb2S. In the third study, the

  6. Impedance analysis of inherently redox-active ionic-liquid-based photoelectrochemical cells: charge-transfer mechanism in the presence of an additional redox couple.

    PubMed

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

    2015-06-01

    An intensive electrochemical impedance study was carried out to understand the charge-transfer processes in photoelectrochemical (PEC) cells based on ionic liquid (IL) electrolytes. Three different electrolytes were utilized to understand the role of redox species as well as the medium on the charge-transfer mechanism. The negligible diffusion resistance, despite the presence of two different redox species in the case of Fe(CN)(6) (-4/-3) in IL, was explained on the basis of charge transfer between species of two different redox couples. Accordingly, the redox species are not required to travel through the bulk of the electrolyte for the removal of accumulated charges, as short-range charge transfer between the IL and the Fe(CN)(6) (-4/-3) species facilitates the removal of accumulated charges. It is also shown that PEC cells utilizing dual redox couples are highly stable with larger photoelectrochmeical windows, >3 V. PMID:25820185

  7. Nanostructure-based WO3 photoanodes for photoelectrochemical water splitting.

    PubMed

    Liu, Xien; Wang, Fengying; Wang, Qing

    2012-06-14

    Nanostructured WO(3) has been developed as a promising water-splitting material due to its ability of capturing parts of the visible light and high stability in aqueous solutions under acidic conditions. In this review, the fabrication, photocatalytic performance and operating principles of photoelectrochemical cells (PECs) for water splitting based on WO(3) photoanodes, with an emphasis on the last decade, are discussed. The morphology, dimension, crystallinity, grain boundaries, defect and separation, transport of photogenerated charges will also be mentioned as the impact factors on photocatalytic performance. PMID:22534756

  8. 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.

  9. Optimization of amorphous silicon double junction solar cells for an efficient photoelectrochemical water splitting device based on a bismuth vanadate photoanode.

    PubMed

    Han, Lihao; Abdi, Fatwa F; Perez Rodriguez, Paula; Dam, Bernard; van de Krol, Roel; Zeman, Miro; Smets, Arno H M

    2014-03-01

    A photoelectrochemical water splitting device (PEC-WSD) was designed and fabricated based on cobalt-phosphate-catalysed and tungsten-gradient-doped bismuth vanadate (W:BiVO4) as the photoanode. A simple and cheap hydrogenated amorphous silicon (a-Si:H) double junction solar cell has been used to provide additional bias. The advantage of using thin film silicon (TF-Si) based solar cells is that this photovoltaic (PV) technology meets the crucial requirements for the PV component in PEC-WSDs based on W:BiVO4 photoanodes. TF-Si PV devices are stable in aqueous solutions, are manufactured by simple and cheap fabrication processes and their spectral response, voltage and current density show an excellent match with the photoanode. This paper is mainly focused on the optimization of the TF-Si solar cell with respect to the remaining solar spectrum transmitted through the W:BiVO4 photoanode. The current matching between the top and bottom cells is studied and optimized by varying the thickness of the a-Si:H top cell. We support the experimental optimization of the current balance between the two sub-cells with simulations of the PV devices. In addition, the impact of the light induced degradation of the a-Si:H double junction, the so-called Staebler-Wronski Effect (SWE), on the performance of the PEC-WSD has been studied. The light soaking experiments on the a-Si:H/a-Si:H double junctions over 1000 hours show that the efficiency of a stand-alone a-Si:H/a-Si:H double junction cell is significantly reduced due to the SWE. Nevertheless, the SWE has a significantly smaller effect on the performance of the PEC-WSD. PMID:24452785

  10. Research on photoelectrochemical cells based on CdSe, CdSe/sub 1-x/Te/sub x/ and other photoelectrode materials

    SciTech Connect

    Wallace, W L

    1984-05-01

    Research on electrochemical photovoltaic cells incorporating thin film n-CdSe and n-CdSe/sub 1-x/Te/sub x/ photoanodes has resulted in efficiencies up to 7.5% using small area electrodes in polysulfide electrolytes. Efficiencies close to 10% can be achieved using alternate electrolytes in significantly less stable systems. The major limitations on the efficiency of II-VI photoelectrochemical cells are associated with the open circuit voltage and the fill factor. Research on CuInSe/sub 2/ electrochemical photovoltaic cells has resulted in efficiencies up to 11.7% using single crystal n-CuInSe/sub 2/ photoanodes in aqueous electrolytes. The n-CuInSe/sub 2/ surface and the electrolyte have been optimized to produce a highly stable semiconductor/electrolyte junction. A review will also be given on the status of photoelectrochemical storage cell research. In situ photoelectrochemical measurement techniques have been used to probe the semiconductor/electrolyte interface and have been used to support the characterization of semiconductor materials for solid state photovoltaic applications.

  11. 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 +/.

  12. 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.

  13. Paper-Based Device for Colorimetric and Photoelectrochemical Quantification of the Flux of H2O2 Releasing from MCF-7 Cancer Cells.

    PubMed

    Li, Li; Zhang, Yan; Zhang, Lina; Ge, Shenguang; Liu, Haiyun; Ren, Na; Yan, Mei; Yu, Jinghua

    2016-05-17

    In this work, a novel dual photoelectrochemical/colorimetric cyto-analysis format was first introduced into a microfluidic paper-based analytical device (μ-PAD) for synchronous sensitive and visual detection of H2O2 released from tumor cells based on an in situ hydroxyl radicals ((•)OH) cleaving DNA approach. The resulted μ-PAD offered an excellent platform for high-performance biosensing applications, which was constructed by a layer-by-layer modification of concanavalin A, graphene quantum dots (GQDs) labeled flower-like Au@Pd alloy nanoparticles (NPs) probe, and tumor cells on the surface of the vertically aligned bamboo like ZnO, which grows on a pyknotic Pt NPs modified paper working electrode (ZnO/Pt-PWE). It was the effective matching of energy levels between GQDs and ZnO levels that lead to the enhancement of the photocurrent response compared with the bare ZnO/Pt-PWE. After releasing H2O2, the DNA strand was cleaved by (•)OH generated under the synergistic catalysis of GQDs and Au@Pd alloy NPs and thus, reduced the photocurrent, resulting in a high sensitivity to H2O2 in aqueous solutions with a detection limit of 0.05 nmol observed, much lower than that in the previously reported method. The disengaged probe can result in catalytic chromogenic reaction of substrates, resulting in real-time imaging of H2O2 biological processes. Therefore, this work provided a truly low-cost, simple, and disposable μ-PAD for precise and visual detection of cellular H2O2, which had potential utility to cellular biology and pathophysiology. PMID:27065042

  14. 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.

  15. 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.

  16. Multiple junction II-VI compound photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Russak, Michael A.

    1986-12-01

    The application of concepts used in producing tandem solid state photovoltaic devices to photoelectrochemical cells has resulted in improved spectral response and photovoltaic output. As in solid state devices, the key to achieving good photovoltaic performance is optimization of the semiconductor properties in each part of the tandem arrangement. This has been done for the thin film CdS/CdSe/sulfide-polysulfide system with an improvement of over 15 percent in conversion efficiency being obtained. Preliminary results showing significant current enhancement by the addition of a CdSe backwall electrode to the CdTe/selenide-polyselenide system are also reported.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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…

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

    PubMed

    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

  5. 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

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

    NASA Astrophysics Data System (ADS)

    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

    2016-02-01

    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.

  7. Highly efficient photoelectrochemical water splitting by a hybrid tandem perovskite solar cell.

    PubMed

    Bin, Abd Rashid; Yusoff, Mohd; Jang, Jin

    2016-04-30

    Herein, we show that graphene can be fully utilized to function as an electrocatalyst in highly efficient photoelectrochemical water splitting. Combining a solution-processed organic photovoltaic and the state-of-the-art perovskite solar cell in a tandem architecture yields a stable short-circuit water splitting photocurrent of ∼7.25 mA cm(-2) under 1 sun illumination. The ∼7.25 mA cm(-2) photocurrent corresponds to a solar-to-hydrogen efficiency of 9.02%, which is the highest efficiency yet reported for water splitting based on a hybrid tandem perovskite solar cell. PMID:27035707

  8. Photoelectrochemical Corrosion of Semiconductors for Solar Cells

    NASA Astrophysics Data System (ADS)

    Madou, M. J.; Frese, K. W.; Morrison, S. R.

    1980-11-01

    Experimental results on stabilization against photo-induced corrosion of n-Si and n-GaAs in contact with electrolytes are given. Photocorrosion is examined on silicon using voltammetry on GaAs using a rotating ring-disk technique. The most extensive testing of stability was done for n-Si in a solution of N,N,N',N'-tetramethyl-p-phenvlenediamine in methanol and for n-GaAs in an aqueous solution of Fe(II) EDTA. Multiple waves were observed for the oxidation of several organic compounds on illuminated n-Si. To explain this auasi-metallic behavior a model based on an intervening thin surface oxide is postulated. In the case of n-GaAs the influence of mechanical surface damage, pH of the solution and redox couple used was studied. It is found that surface defects areativ enhance the susceptibility of the GaAs to photo-induced corrosion.

  9. 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. PMID:26523921

  10. Conversion of sunlight into electrical power and photoassisted electrolysis of water in photoelectrochemical cells

    SciTech Connect

    Heller, A.

    1981-05-01

    The development of photoelectrochemical solar cells based on semiconductor liquid junctions is discussed. Over the past 6 years, the efficiency of solar energy conversion has increased from < 1% to 12%, and the operational life of these cells has increased from hours to months. Understanding the chemistry of surfaces and grain boundaries has made it possible to manipulate the position of the surface and grain boundary states and thus reduce losses due to electron-hole recombination. Cells exhibiting approx. 12% efficiency of conversion are: (1) chemisorbed Ru/sup 3 +/ ions on n-GaAs photoanodes; (2) diffused Ru/sup 3 +/ and Pb/sup 2 +/ into grain boundaries of polycrystalline n-GaAs films on graphite; (3) p-InP/VCl/sub 3/-VCl/sub 2/-HCl/C cell; and (4) p-InP(Ru)/HCl-KCl/Pt cell. Photoassisted electrolysis of water for conversion of solar energy to hydrogen using the last mentioned photoelectrochemical cell represents the most efficient system for solar energy conversion. 61 references are cited. (BLM)tic stainless steel is required to prevent stress corrosion cracking byd stuffs contamination in the USSR takes place in the framework of variations observed in separate countries of northern hemisphere.

  11. 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

  12. 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.

  13. A one-volt p-InP/n-CdSe regenerative photoelectrochemical cell

    SciTech Connect

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

    1983-08-01

    Photoelectrochemical (PEC) cells have the potential utility of being used for either the direct conversion of solar energy to electricity as in regenerative devices or to generate stored redox species which can later be electrochemically discharged in a suitable cell. This latter approach has been particularly intriguing over the last few years. However, although several photoelectrochemical storage cells have been discussed, it has become increasingly desirable to have a high-voltage (approx. =1 V) PEC cell, so that the storage cell with which it is associated has some hope of being competitive with presently available commercial batteries.

  14. 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.

  15. 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.

  16. 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

  17. Surface defects on n-MoSe2 electrodes used in photoelectrochemical solar cells

    NASA Astrophysics Data System (ADS)

    Peraldo Bicelli, L.; Razzini, G.

    1983-12-01

    It is pointed out that stable and efficient electrochemical solar cells based on layered semiconducting materials have been obtained with single-crystal electrodes. It is necessary that the electrode materials have a very high degree of crystalline perfection, while the active surface of the electrode must be parallel to the van der Waals plane. The present investigation is concerned with two problems, taking into account the influence of local variations in the stoichiometric composition of the electrode material on the performance, and the photocatalytic process occurring on the active areas of the electrode. The obtained results provide information concerning the problems which have to be solved to obtain transition metal dichalcogenide electrodes for solid-liquid junction cells with an photoelectrochemical behavior suitable for practical applications.

  18. 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

  19. Visible light induced photoelectrochemical biosensing based on oxygen-sensitive quantum dots.

    PubMed

    Wang, Wenjing; Bao, Lei; Lei, Jianping; Tu, Wenwen; Ju, Huangxian

    2012-09-26

    A visible light induced photoelectrochemical biosensing platform based on oxygen-sensitive near-infrared quantum dots (NIR QDs) was developed for detection of glucose. The NIR QDs were synthesized in an aqueous solution, and characterized with scanning electron microscopy and X-ray photoelectron spectroscopy. The as-prepared NIR QDs were employed to construct oxygen-sensitive photoelectrochemical biosensor on a fluorine-doped tin oxide (FTO) electrode. The oxygen dependency of the photocurrent was investigated at as-prepared electrode, which demonstrated the signal of photocurrent is suppressed with the decreasing of oxygen. Coupling with the consumption of oxygen during enzymatic reaction, a photoelectrochemical strategy was proposed for the detection of substrate. Using glucose oxidase (GOx) as a model enzyme, that is, GOx was covalently attached to the surface of CdTe QDs, the resulting biosensor showed the sensitive response to glucose. Under the irradiation of visible light of a wavelength at 505 nm, the proposed photoelectrochemical method could detect glucose ranging from 0.1 mM to 11 mM with a detection limit of 0.04 mM. The photoelectrochemical biosensor showed a good performance with high upper detection limit, acceptable stability and accuracy, providing an alternative method for monitoring biomolecules and extending the application of near-infrared QDs. PMID:22935371

  20. Photoelectrochemical scanning droplet cell microscopy for localized photovoltaic investigations on organic semiconductors.

    PubMed

    Gasiorowski, Jacek; Kollender, Jan Philipp; Hingerl, Kurt; Sariciftci, Niyazi Serdar; Mardare, Andrei Ionut; Hassel, Achim Walter

    2014-02-28

    Photoelectrochemical characterization of the regioregular poly(3-hexylthiophene) (P3HT) was performed using an adapted version of a photoelectrochemical scanning droplet cell microscope (PE-SDCM). The real and imaginary parts of the dielectric function were determined using spectroscopic ellipsometry in order to identify the absorption region of the polymer. Detailed photoelectrochemical experiments were performed for the thin polymer layer contacted with 0.1 M tetrabutylammonium hexafluorophosphate dissolved in propylene carbonate as well as with an electrolyte containing a 5.4 mM ferrocene/ferrocenium redox couple. The effect of the illumination on the P3HT covered WE in contact with both the pure electrolyte and an electrolyte containing a ferrocene/ferrocenium redox couple was studied using dark/illumination sequences. The stability of the photovoltaic effect was characterized using long term current transients. Finally, the photoelectrochemical impedance spectroscopy was applied to determine the electrical properties of the P3HT in the dark and under illumination. PMID:24424428

  1. Porous copper zinc tin sulfide thin film as photocathode for double junction photoelectrochemical solar cells.

    PubMed

    Dai, Pengcheng; Zhang, Guan; Chen, Yuncheng; Jiang, Hechun; Feng, Zhenyu; Lin, Zhaojun; Zhan, Jinhua

    2012-03-21

    Porous copper zinc tin sulfide (CZTS) thin film was prepared via a solvothermal approach. Compared with conventional dye-sensitized solar cells (DSSCs), double junction photoelectrochemical cells using dye-sensitized n-type TiO(2) (DS-TiO(2)) as the photoanode and porous p-type CZTS film as the photocathode shows an increased short circuit current, external quantum efficiency and power conversion efficiency. PMID:22322239

  2. 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. PMID:25190086

  3. 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. PMID:26592360

  4. Zinc selenide photoelectrodes: efficient radiative recombination in a stable photoelectrochemical cell

    SciTech Connect

    Smiley, P.M.; Biagioni, R.N.; Ellis, A.B.

    1984-05-01

    A study has been made of photoluminescence (PL) and electroluminescence (EL) from single-crystal n-type ZnSe:Al electrodes. It is shown that emission from the electrodes, with a measured radiative quantum yield of 0.1-0.01, competes favorably with other deactivation paths in stable efficient photoelectrochemical cells. As observed with other semiconductor electrodes, the PL of n-ZnSe:Al electrodes can be perturbed and EL initiated by interfacial charge-transfer processes. It is shown that PL quenching by applied potential is compatible with a dead-layer model used to describe such quenching in other photoelectrochemical cells and in Au-ZnSe Schottky diodes. 24 references.

  5. 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.

  6. 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.

  7. Photoenergy storage and power amplification strategy in membrane-less photoelectrochemical biofuel cells.

    PubMed

    Yu, You; Xu, Miao; Dong, Shaojun

    2016-05-10

    The photoelectrochemical biofuel cell (PBFC) has drawn great attention because of its potential in the conversion of both photoenergy and chemical energy from biomass into electricity. Herein, we proposed a novel integrated PBFC by insetting a third electrode with high efficiency energy storage and release between the bioelectrode and the photoelectrode, resulting in a higher power output than that of the original PBFC. PMID:27117777

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. Linker-free deposition and adhesion of Photosystem I onto nanostructured TiO2 for biohybrid photoelectrochemical cells.

    PubMed

    Shah, Vivek B; Henson, William R; Chadha, Tandeep S; Lakin, Gerard; Liu, Haijun; Blankenship, Robert E; Biswas, Pratim

    2015-02-10

    Photosystem I (PSI) from oxygenic photosynthetic organisms is an attractive sensitizer for nano-biohybrid solar cells as it has a combined light-harvesting and reaction center in one protein complex and operates at a quantum yield close to one in biological systems. Using a linker-free deposition technique enabled by an electrospray system, PSI was coupled to 1-D nanostructured titanium dioxide thin films to fabricate an electrode for a photoelectrochemical cell. After deposition, the surfactant in the PSI aggregate was dissolved in the surfactant-free electrolyte, ensuring that partly hydrophobic PSI was not resuspended and stayed in contact with titanium dioxide. A maximum current density of 4.15 mA cm(-2) was measured after 10 min of electrospray deposition, and this is the highest current density reported so far for PSI-based photoelectrochemical cells. The high current is attributed to 1D nanostructure of titanium dioxide and orientation of the PSI onto the surface, which allows easy transfer of electrons. PMID:25540979

  13. 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.

  14. 1-(3'-Amino)propylsilatrane derivatives as covalent surface linkers to nanoparticulate metal oxide films for use in photoelectrochemical cells.

    PubMed

    Brennan, Bradley J; Keirstead, Amy E; Liddell, Paul A; Vail, Sean A; Moore, Thomas A; Moore, Ana L; Gust, Devens

    2009-12-16

    A triethanolamine-protected silane, 1-(3'-amino)propylsilatrane, was incorporated into the structure of porphyrin- and ruthenium-based dyes and used to link them to transparent semiconductor nanoparticulate metal oxide films. Silatrane reacts with the metal oxide to form strong, covalent silyl ether bonds. In this study, silatrane-functionalized dyes and analogous carboxylate-functionalized dyes were used as visible light sensitizers for porous nanoparticulate SnO(2) photoanodes. The performance of the dyes was compared in photoelectrochemical cells incorporating either non-regenerative or regenerative redox components. The non-regenerative cell used NADH (beta-nicotinamide adenine dinucleotide) as a sacrificial electron donor and Hg(2)SO(4)/Hg as a sacrificial cathode, whereas the regenerative cell used the iodide/triiodide redox couple. Experiments showed that the silyl ether bonding gave the electrodes increased stability toward sensitizer desorption compared to carboxylate surface linkages. Porphyrin-silatrane dyes also demonstrated similar or better performance than their carboxylate analogs in photoelectrochemical cells. The improvement correlates with the results from transient absorbance spectroscopy, which show that the longer linker on the silatrane porphyrins slows charge recombination between oxidized porphyrin and the electrode surface. The improved photoelectrochemical cell efficiency and stability of the silatrane-based dyes compared to carboxylates demonstrate that silatranes are promising agents for bonding organic molecules to metal oxide surfaces. PMID:19923652

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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/cm2), 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.

  16. Zinc selenide photoelectrodes. Efficient radiative recombination in a stable photoelectrochemical cell. Technical report

    SciTech Connect

    Smiley, P.M.; Biagioni, R.N.; Ellis, A.B.

    1984-05-25

    Photoluminescence (PL) and electroluminescence (EL) from single-crystal, n-type, A1-doped ZnSe (ZnSe:A1) electrodes have been studied. These samples exhibit both edge emission (lambda(max) approx. 460 nm) and subband gap emission when excited at several ultraband gap wavelengths. The latter PL band is particularly intense, with a measured radiative quantum yield of approx. 0.1 to 0.01; the transition seems at least partially self-activated (SA) in origin, based on previously reported PL data. Excited-state communication involving the two emissive states is inferred from time-resolved PL measurements. Stable photoelectrochemical cells (PEC's) can be constructed from n-ZnSe:A1 electrodes and aqueous diselenide or ditelluride electrolytes. Applied potential quenches both of the photoanodes' PL bands roughly in parallel. The extent of PL quenching is consistent with a dead-layer model previously used to describe quenching in Au-ZnSe Schottky diodes. When used as a dark cathode in aqueous, alkaline peroxydisulfate eletrolyte, EL from ZnSe:A1 electrodes is observed.

  17. 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.

  18. A photoelectrochemical cell for the study of the photosensitive materials used in solar-hydrogen energy

    NASA Astrophysics Data System (ADS)

    Ardelean, P.; Indrea, E.; Silipas, T. D.; Ardelean, C.; Mihailescu, G. H.; Suciu, Ramona-Crina; Dreve, Simina Virginia; Moldovan, Z.; Corina Rosu, Marcela

    2009-08-01

    It was built a versatile photoelectrochemical cell devoted to the comparative study of the photosensitive materials used as photoelectrodes in solar-hydrogen production. The experimental arrangement makes possible a relative evaluation of the electrodes properties by the measurement of the electric parameters, giving directly I = f (U) for the cell electric circuit with and without an external electrical bias. It also gives a direct measurement of the volume of the evolved gases, and an on-line analysis of the gases by the coupled gas chromatograph, or of-line, by a mass spectrometer.

  19. 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.

  20. 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.

  1. 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. PMID:26476013

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

    PubMed

    Kollender, Jan Philipp; Gasiorowski, Jacek; Sariciftci, Niyazi S; Mardare, Andrei I; Hassel, Achim Walter

    2014-07-31

    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

  3. 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

  4. 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…

  5. Study of Cd-chalcogenide/ferri-ferrocyanide photoelectrochemical cells: effect of surface morphology and added salt

    SciTech Connect

    Tenne, R.

    1983-11-01

    The authors carried out an investigation of the Cd-chalcogenide/ferri-ferrocyanide photoelectrochemical cells. In particular, the effect of surface morphology and the effect of added salts upon the characteristics of these cells were investigated. Successive etching with Br/sub 2/ (3%)/methanol, aqua regia, and finally photoetching increases the surface roughness of CdSe (CdS, CdTe) which has a marked effect on the cell characteristics in the ferri-ferrocyanide electrolyte (and polysulfide electrolyte as well). In contrast with polysulfide electrolyte, added salts decrease the output stability of the cell and the onset potential for the photocurrent, which can be explained by the removal of the physiosorbed ferrocyanide ions from the electrode surface by the ions of the salt. On increasing the surface roughness of the electrode, while keeping the salt concentration unchanged, the output stability and the onset potential were increased. A kinetic model is used to explain these phenomena. Thus, added salts can be used to probe the strength of the adsorption of the active electrolyte on the surface of the photoelectrode. Finally, we report on the surface morphology of CdSe and CdTe after irradiation in ferri-ferrocyanide solution and compare our findings to surface morphologies which were observed previously with the help of photoelectrochemical etching (photoetching). It is found that small rectangular crystallites, probably of cadmium ferrocyanide, deposit on the crystal surface during the photocorrosion process in addition to elemental Se(Te).

  6. Self-biasing photoelectrochemical cell for spontaneous overall water splitting under visible-light illumination.

    PubMed

    Chen, Quanpeng; Li, Jinhua; Li, Xuejin; Huang, Ke; Zhou, Baoxue; Shangguan, Wenfeng

    2013-07-01

    A self-biasing photoelectrochemical (PEC) cell that could work for spontaneous overall water splitting in a neutral solution was established based on the mismatched Fermi levels between the photoelectrodes. A Pt-catalyst-decorated crystalline silicon photovoltaic cell (Pt/PVC) was prepared and employed as an effective photocathode. This was coupled with a poly(ethylene glycol)-directed WO3/W photoanode prepared by a hydrothermal process. Both of the photoelectrodes showed a response to visible light. The WO3/W photoanode had a positively located valence band edge, the energy level of which was enough for water oxidation, and the Pt/PVC photocathode possessed a negatively located conduction band edge, which was capable of water reduction. More importantly, the Fermi level of the WO3/W photoanode was more positive than that of the Pt/PVC photocathode because of the p-n junction of the PVC that decoupled the band bending and enlarged the photovoltage. Under visible-light irradiation, the WO3/W photoanode provided a negative bias for the Pt/PVC photocathode, and the Pt/PVC photocathode provided a positive bias for the WO3/W photoanode. An interior bias was generated that could relax the strict criteria of overall water splitting by cooperatively separating the hole-electron pairs at both photoelectrodes. In this system, the short-circuit current and the open-circuit voltage increased with increasing light intensity (AM 1.5 illumination) to reach 121 μA cm(-2) and 0.541 V, respectively, at a light intensity of 100 mW cm(-2). Such a combination provides a promising method for the fabrication of self-driven devices for solar-energy storage. PMID:23775929

  7. 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

  8. Solar water splitting in a molecular photoelectrochemical cell.

    PubMed

    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

    2013-12-10

    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

  9. 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

  10. 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

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

    PubMed

    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

  12. Reaction kinetics and product distributions in photoelectrochemical cells

    SciTech Connect

    Koval, C.A.

    1992-01-01

    Hot electron reaction studies at p-InP/CH[sub 3]CN interface revealed essential/desirable features for redox systems used to investigate hot carriers in photoelectrocehmical cells. Reduction of dibromoethylbenzene (DBEB) in presence of metallocene couples is being studied using rotating rink disk electrodes of n-and p-InP disks and Pt rings. At highly doped p-InP electrodes, reduction of DBEB can be very efficient (>30%). A minielectrochemical cell was used to investigate electron transfer at nonilluminated n-WSe[sub 2]/dimethylferrocene[sup +/0] interfaces.

  13. Electrodeposition and Screening of Photoelectrochemical Activity in Conjugated Polymers Using Scanning Electrochemical Cell Microscopy.

    PubMed

    Aaronson, Barak D B; Garoz-Ruiz, Jesus; Byers, Joshua C; Colina, Alvaro; Unwin, Patrick R

    2015-11-24

    A number of renewable energy systems require an understanding and correlation of material properties and photoelectrochemical activity on the micro to nanoscale. Among these, conducting polymer electrodes continue to be important materials. In this contribution, an ultrasensitive scanning electrochemical cell microscopy (SECCM) platform is used to electrodeposit microscale thin films of poly(3-hexylthiophene) (P3HT) on an optically transparent gold electrode and to correlate the morphology (film thickness and structural order) with photoactivity. The electrochemical growth of P3HT begins with a thin ordered film up to 10 nm thick, after which a second more disordered film is deposited, as revealed by micro-Raman spectroscopy. A decrease in photoactivity for the thicker films, measured in situ immediately following film deposition, is attributed to an increase in bulk film disorder that limits charge transport. Higher resolution ex situ SECCM phototransient measurements, using a smaller diameter probe, show local variations in photoactivity within a given deposit. Even after aging, thinner, more ordered regions within a deposit exhibit sustained enhanced photocurrent densities compared to areas where the film is thicker and more disordered. The platform opens up new possibilities for high-throughput combinatorial correlation studies, by allowing materials fabrication and high spatial resolution probing of processes in photoelectrochemical materials. PMID:26502089

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

    DOE PAGESBeta

    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

  15. 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

  16. ZnO nanoflower-based photoelectrochemical DNAzyme sensor for the detection of Pb2+.

    PubMed

    Zhang, Bintian; Lu, Lili; Hu, Qichang; Huang, Feng; Lin, Zhang

    2014-06-15

    Lead contamination is now widespread, and exposure to lead may cause adverse effects on human beings. In this study, a photoelectrochemical sensor based on flower-like ZnO nanostructures was developed for Pb(2+) detection, using a Pb(2+)-dependent DNAzyme as the recognition unit and a double-strand DNA intercalator, Ru(bpy)2(dppz)(2+) (bpy=2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c] phenazine) as the photoelectrochemical signal reporter. The ZnO nanoflower was fabricated on an indium tin oxide (ITO) electrode by the convenient hydrothermal decomposition method. The morphology and photoelectrochemical property of the ZnO nanoflowers were characterized by SEM, XRD and photocurrent measurements. DNAzyme-substrate duplex was assembled on an ITO/ZnO electrode through electrostatic adsorption. In the presence of Pb(2+), RNA-cleavage activity of the DNAzyme was activated and its substrate strand was cleaved, resulting in the release of Ru(bpy)2(dppz)(2+) from the DNA film and the concomitant photocurrent decrease. The detection principle was verified by fluorescence measurements. Under the optimized conditions, a linear relationship between photocurrent and Pb(2+) concentration was obtained over the range of 0.5-20 nM, with a detection limit of 0.1 nM. Interference from other common metal ions was found negligible. Applicability of the sensor was demonstrated by analyzing lead level in human serum and Pb(2+) spiked water samples. This facile and economical sensor system showed high sensitivity and selectivity, thus can be potentially applied for on-site monitoring of lead contaminant. PMID:24508815

  17. 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%.

  18. 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.

  19. Highly efficient and stable Si nanowires array embedded into transparent polymer for visible light photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Wang, Jian-Tao; Ou, Xue-Mei; Li, Fan; Zhang, Xiao-Hong

    2014-07-01

    Photoelectrochemical (PEC) cell supports a renewable method for solving current environmental and energy issues by combining solar energy collection and photocatalysis in a single semiconductor photoelectrode. However, it is still challenged by visible light photoelectrodes. The present work reports fabricating highly efficient and stable Si nanowires (SiNWs) array as visible light photoelectrodes. It involves embedding SiNWs arrays into a transparent polymer substrate to build an axial carrier collection geometry. We demonstrated that this strategy could significantly strengthen the chemical stability of SiNWs by largely reducing their surface area. Moreover, this device structure can also enhance visible light absorption efficiency through taking advantage of the highly crystalline structure of vapor-liquid-solid (VLS) grown SiNWs. Thus it can double the photodegradation ability of SiNWs.

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

    SciTech Connect

    Cahen, D.; Chen, Y.W.

    1985-12-17

    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.

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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. PMID:26971805

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

    PubMed

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

    2016-01-28

    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. PMID:26731449

  8. Electron transfer kinetics in water-splitting dye-sensitized photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Swierk, John R.

    Water-splitting dye-sensitized photoelectrochemical (WS-DSPECs) cells utilize molecular sensitizers absorbed on mesoporous TiO2 electrodes to harvest visible light, inject photoexcited electrons into the conduction band of TiO2, and finally transfer holes across the TiO2 surface to water oxidation catalysts, which in turn oxidize water to give molecular oxygen and four protons. Within the TiO2 layer photoinjected electrons are transported to a transparent conductor back contact and from there to a dark cathode to reduce protons to molecular hydrogen. WS-DSPECs offer several advantages for alternative solar fuels systems: the use of low-cost materials, tunable molecular sensitizers, and relaxed catalytic turnover requirements to name a few. Despite these advantageous features, power conversion efficiencies in WS-DSPECs are generally low. Broadly, this thesis explores the fundamental electron transfer processes that control the efficiency of these cells. Chapter 1 presents a survey of the previous literature and individually considers each component of a WS-DSPEC (water oxidation catalyst, sensitizers, electrode materials, redox mediators, and overall system design). Chapter 2 presents a novel method of preparing a WS-DSPEC that utilizes crystalline IrO2 nanoparticles directly sintered to TiO2 as a water oxidation catalyst and describes a previously unknown electron-scavenging pathway by IrO2. Chapter 3 explores how electron trapping by and proton intercalation into TiO2 controls the photoelectrochemical performance of WS-DSPECs. Chapter 4 characterizes how electron recombination with the oxidized sensitizer and electron scavenging by the IrO 2 catalyst combine to limit the concentration of conduction band electrons and by extension photocurrent in WS-DSPECs. Chapter 5 demonstrates the use of the first totally organic sensitizers for light driven water-splitting and explores how the molecular and electronic structure of a sensitizer affects the electron transfer

  9. Layered transition metal thiophosphates /MPX3/ as photoelectrodes in photoelectrochemical cells

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Smith, B. T.; Reichman, B.

    1982-01-01

    Layered crystals of the transition metal thiophosphates were synthesized and characterized for use as photoelectrodes in photoelectrochemical cells. Crystals incorporating tin and manganese show n-type response while those with iron and nickel show p-type response. These materials have a measured indirect bandgap of about 2.1 eV. They show ability to photoelectrolyze water in acid solutions with onset potentials which change in a Nernstian way as the PH of the solution changes. The onset potential is near zero volts versus a saturated calomel electrode at pH 2. At n-type crystals, oxygen could be evolved upon irradiation at underpotentials of 850 mV and at p-type crystals, hydrogen could be evolved at underpotentials of 400 mV, indicating a net gain in energy conversion. All crystals were unstable in basic solution. Liquid junction photovoltaic cells in iodide-triiodide acid solution using these layered materials were also constructed and found to have low efficiences.

  10. Electrochemical synthesis of SnS thin films for photoelectrochemical cells

    NASA Astrophysics Data System (ADS)

    Subramanian, B.; Sanjeevi Raja, C.; Jayachandran, M.; Chockalingam, Mary J.

    1999-11-01

    Tin Sulphide (SnS), a layered semiconducting material which finds wide applications in optoelectronic devices and window material for heterojunction solar cell. This paper reports on the material properties of thin films of SnS prepared by electrodeposition and brush plating. Brush plating is an electroplating process usually adopted to coat large area thin metal or alloy film. The films of 0.6-1.0 μm and 1.0-2.5 μm thickness were prepared by electrodeposition and brush plating respectively. X-ray diffraction studies showed that the as prepared films of both techniques revealed polycrystalline nature of the films and the lattice parameter values are: a=0.403 nm; b=1.145 nm; and c=0.399 nm. The surfaces were analyzed by electron spectroscopy for chemical analysis and SEM for surface morphology. The band gap, refractive index and extinction coefficient values were estimated from the optical studied in the wavelength region of 400-1500 nm. The adhesion of the films prepared by brush plating was found to be excellent. Photoelectrochemical solar cells were fabricated using SnS photoelectrodes. Capacitance-voltage studies revealed the p- type nature of all the films. The flat band potentials were 0.52 V and 0.47 V respectively. The quality of the films prepared by electrodeposition and brush plating are compared.

  11. 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

  12. 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

  13. Detection of esophageal cancer cell by photoelectrochemical Cu2O/ZnO biosensor (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hsu, Chao-Hsin; Chu, Cheng-Hsun; Chen, Weichung; Wu, I.-Chen; Wu, Ming Tsang; Kuo, Chie-Tong; Tsiang, Raymond Chien-Chao; Wang, Hsiang-Chen

    2016-03-01

    We have demonstrated a Cu2O/ZnO nanorods (NRs) array p-n heterostructures photoelectrochemical biosensor. The electrodeposition of Cu2O at pH 12 acquired the preferably (111) lattice planes, resulting in the largest interfacial electric field between Cu2O and ZnO, which finally led to the highest separation efficiency of photogenerated charge carriers. High verticality ZnO nanorods by seed layer and thermal annealing assist the hydrothermal growth. The optimized Cu2O/ZnO NRs array p-n heterostructures exhibited enhanced PEC performance, such as elevated photocurrent and photoconversion efficiency, as well as excellent sensing performance for the sensitive detection of four strains of different races and different degree of cancer cell which made the device self-powered. We got spectral response characteristics and operating wavelength range of biosensor, and to verify the biological characteristics of cancer cells wafer react with different stages of cancer characterized by a cancer measured reaction experiment.

  14. Formation of surface morphology of silicon solar cells by means of two-step photo-electrochemical etching and their characterization

    NASA Astrophysics Data System (ADS)

    Shatkovskis, E.; Zagadskij, V.; Jukna, A.; Boris, R.; Antonovic, V.; Stupakova, J.; Mitkevicius, R.; Baradinskaite, A.; Keriene, J.

    2014-10-01

    The electrochemical etching of porous silicon offers many diverse opportunities for production of complex porous silicon structures located not only on the surface but also in a bulk of the silicon devices. A specific technological regime, the photo-electrochemical etching can affect bulk of the silicon device but at the same time saving its textured surface almost unchanged. Our group is the first who investigated the silicon solar cells with textured surface modified by means of photo-electrochemical etching. Etched devices demonstrated better photoelectrical characteristics if compare ones with unmodified solar cells. Our current work presents results on research of solar cells photoelectrochemically treated in HF: ethanol solution. Applied etching regime allowed us to modify the emitter's volume at the same time affecting only minimally the surface of the solar cell itself. SEM micrographs show the elevations, ripples, bumps, cracks etc. on the surface of photo-electrochemically treated solar cells. The optical ellipsometer spectra, optical microscope measurements results, SEM micrographs of surface morphology as well as light reflectivity of the photoelectrochemically treated and untreated surfaces of the solar cells investigated and discussed in this work.

  15. 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.

  16. 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)), PMID:26334564

  17. The study of the photosensitive materials used in solar-hydrogen energy by a versatile photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Ardelean, P.; Indrea, E.; Ardelean, C.; Mihailescu, Gh.; Balazs, Z.; Silipas, T. D.; Moldovan, Z.; Suciu, R. C.; Dreve, S. V.; Rosu, M. C.

    2012-02-01

    In this paper it was made a comparative study of the doped TiO2 thin films used as photoelectrodes by using a versatile photoelectrochemical cell. The experimental arrangement makes possible the relative evaluation of the electrodes properties by measurement of the electric parameters, giving directly I = f(U) for the cell electric circuit by using an "internal" chemical bias. It is also possible to measure the volume of the evolved gas, and to analyze it by a gas-chromatograph and by a mass spectrometer.

  18. 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. PMID:26291091

  19. Solar-Energy-Driven Photoelectrochemical Biosensing Using TiO2 Nanowires.

    PubMed

    Tang, Jing; Li, Jun; Da, Peimei; Wang, Yongcheng; Zheng, Gengfeng

    2015-08-01

    Photoelectrochemical sensing represents a unique means for chemical and biological detection, with foci of optimizing semiconductor composition and electronic structures, surface functionalization layers, and chemical detection methods. Here, we have briefly discussed our recent developments of TiO2 nanowire-based photoelectrochemical sensing, with particular emphasis on three main detection mechanisms and corresponding examples. We have also demonstrated the use of the photoelectrochemical sensing of real-time molecular reaction kinetic measurements, as well as direct interfacing of living cells and probing of cellular functions. PMID:25962650

  20. 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

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

    PubMed Central

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

    2015-01-01

    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+ ([RuaII-RubII-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|-[RuaII-RubII-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/cm2 with 445-nm, ∼90-mW/cm2 illumination in a phosphate buffer at pH 7. PMID:25918426

  2. 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

  3. 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

  4. 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

  5. Photoelectrochemical sensing of 4-chlorophenol based on Au/BiOCl nanocomposites.

    PubMed

    Yan, Pengcheng; Xu, Li; Xia, Jiexiang; Huang, Yan; Qiu, Jingxia; Xu, Qian; Zhang, Qi; Li, Huaming

    2016-08-15

    The Au/BiOCl composites have been prepared by a facile one-pot ethylene glycol (EG) assisted solvothermal reaction in the presence of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl). During the synthesis procedure, the [C16mim]Cl has been used as Cl source, solvent of this system, and dispersing agent to effectively disperse Au on the surface of BiOCl. The as-prepared samples have been systematically characterized by multiple instruments to investigate the structure, morphology, and photoelectrochemical properties. According to the photoelectrochemical data, the Au/BiOCl composites exhibit better photoelectrochemical performance toward the detection of 4-chlorophenol than that of the pure BiOCl. The photocurrent response of Au/BiOCl modified electrode is high and stable under light irradiation. The proposed Au/BiOCl modified electrode shows a wide linear response ranging from 0.16 to 20mgL(-1) with detection limit of 0.05mgL(-1). It indicates a dramatically promising application of bismuth oxyhalides in photoelectrochemical detection. It will be expected that the present study may be lightly extended to the monitor of other organic pollutants by photoelectrochemical detection of the Au/BiOCl composites. PMID:27260461

  6. 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.

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

    DOE PAGESBeta

    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

  8. Photoelectrochemical lab-on-paper device based on an integrated paper supercapacitor and internal light source.

    PubMed

    Ge, Lei; Wang, Panpan; Ge, Shenguang; Li, Nianqiang; Yu, Jinghua; Yan, Mei; Huang, Jiadong

    2013-04-16

    In this work, a photoelectrochemical (PEC) method was introduced into a microfluidic paper-based analytical device (μ-PAD), and thus, a truly low-cost, simple, portable, and disposable microfluidic PEC origami device (μ-PECOD) with an internal chemiluminescence light source and external digital multimeter (DMM) was demonstrated. The PEC responses of this μ-PECOD were investigated, and the enhancements of photocurrents in μ-PECOD were observed under both external and internal light sources compared with that on a traditional flat electrode counterpart. As a further amplification of the generated photocurrents, an all-solid-state paper supercapacitor was constructed and integrated into the μ-PECOD to collect and store the generated photocurrents. The stored electrical energy could be released instantaneously through the DMM to obtain an amplified (∼13-fold) and DMM-detectable current as well as a higher sensitivity than the direct photocurrent measurement, allowing the expensive and sophisticated electrochemical workstation or lock-in amplifier to be abandoned. As a model, sandwich adenosine triphosphate (ATP)-binding aptamers were taken as molecular reorganization elements on this μ-PECOD for the sensitive determination of ATP in human serum samples in the linear range from 1.0 pM to 1.0 nM with a detection limit of 0.2 pM. The specificity, reproducibility, and stability of this μ-PECOD were also investigated. PMID:23472854

  9. 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

  10. 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

  11. An ultrasensitive and universal photoelectrochemical immunoassay based on enzyme mimetics enhanced signal amplification.

    PubMed

    Wang, Guang-Li; Shu, Jun-Xian; Dong, Yu-Ming; Wu, Xiu-Ming; Li, Zai-Jun

    2015-04-15

    An ultrasensitive photoelectrochemical (PEC) immunoassay based on signal amplification by enzyme mimetics was fabricated for the detection of mouse IgG (as a model protein). The PEC immunosensor was constructed by a layer-by-layer assembly of poly (diallyldimethylammonium chloride) (PDDA), CdS quantum dots (QDs), primary antibody (Ab1, polyclonal goat antimouse IgG), and the antigen (Ag, mouse IgG) on an indium-tin oxide (ITO) electrode. Then, the secondary antibody (Ab2, polyclonal goat antimouse IgG) combined to a bio-bar-coded Pt nanoparticle(NP)-G-quadruplex/hemin probe was used for signal amplification. The bio-bar-coded Pt NP-G-quadruplex/hemin probe could catalyze the oxidation of hydroquinone (HQ) using H2O2 as an oxidant, demonstrating its intrinsic enzyme-like activity. High sensitivity for the target Ag was achieved by using the bio-bar-coded probe as signal amplifier due to its high catalytic activity, a competitive nonproductive absorption of hemin and the steric hindrance caused by the polymeric oxidation products of HQ. For most important, the oxidation product of HQ acted as an efficient electron acceptor of the illuminated CdS QDs. The target Ag could be detected from 0.01pg/mL to 1.0ng/mL with a low detection limit of 6.0fg/mL. The as-obtained immunosensor exhibited high sensitivity, good stability and acceptable reproducibility. This method might be attractive for clinical and biomedical applications. PMID:25437365

  12. 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

  13. Enhanced photo-electrochemical performances of graphene-based composite functionalized by Zn2+ tetraphenylporphyrin

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongqiang; Zhu, Junwu; Han, Qiaofeng; Cui, Hao; Bi, Huiping; Wang, Xin

    2014-12-01

    Inspired by the role of electron transport chain in chlorophyll, graphene (G) complexation with zinc 5, 10, 15, 20-tetraphenylporphyrin (ZnTPP) is expected to have excellent photo-electrochemical performances. Here, we design a facile strategy to synthesize the functionalized graphene/zinc tetraphenylporphyrin (G/ZnTPP) composite. In which, all characterizations indicate synergistic effect does exist between graphene sheets and ZnTPP. The synergistic effect enables such composite to possess improved photo-electrochemical behaviors that are key features for photoelectric conversion device. On the basis of this, attempts to modify the absorption range, improve specific capacitance and lower resistance to acquire effective photo-current responses have been successfully demonstrated in this research.

  14. Selective modulation of charge-carrier transport of a photoanode in a photoelectrochemical cell by a graphitized fullerene interfacial layer.

    PubMed

    Park, Sun-Young; Lim, Dong Chan; Hong, Eun Mi; Lee, Joo-Yeoul; Heo, Jinhee; Lim, Jae Hong; Lee, Chang-Lyoul; Kim, Young Dok; Mul, Guido

    2015-01-01

    We show that a graphitic carbon interfacial layer, derived from C70 by annealing at 500 °C, results in a significant increase in the attainable photocurrent of a photoelectrochemical cell that contains a WO3 -functionalized fluorine-doped tin oxide (FTO) photoanode. Time-resolved photoluminescence spectroscopy, photoconductive atomic force microscopy, Hall measurements, and electrochemical impedance spectroscopy show that the increase in photocurrent is the result of fast and selective electron transport from optically excited WO3 through the graphitic carbon interfacial layer to the FTO-coated glass electrode. Thus the energy efficiency of perspective solar-to-fuel devices can be improved by modification of the interface of semiconductors and conducting substrate electrodes by using graphitized fullerene derivatives. PMID:25410298

  15. 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

  16. An ultrasensitive "on-off-on" photoelectrochemical aptasensor based on signal amplification of a fullerene/CdTe quantum dots sensitized structure and efficient quenching by manganese porphyrin.

    PubMed

    Li, Mengjie; Zheng, Yingning; Liang, Wenbin; Yuan, Yali; Chai, Yaqin; Yuan, Ruo

    2016-06-21

    In this work, an ultrasensitive "on-off-on" photoelectrochemical (PEC) aptasensor was proposed based on the signal amplification of a fullerene/CdTe quantum dot (nano-C60/CdTe QDs) sensitized structure and efficient signal quenching of nano-C60/CdTe QDs by a manganese porphyrin (MnPP). PMID:27272457

  17. 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

  18. Photoelectrochemical lab-on-paper device based on molecularly imprinted polymer and porous Au-paper electrode.

    PubMed

    Wang, Panpan; Sun, Guoqiang; Ge, Lei; Ge, Shenguang; Yu, Jinghua; Yan, Mei

    2013-09-01

    In this work, microfluidic paper-based analytical device (μ-PAD) was applied in a photoelectrochemical (PEC) method and thus a truly low-cost, simple, portable, and disposable microfluidic PEC origami device (μ-PECOD) was demonstrated. The molecular imprinting technique was introduced into microfluidic paper-based analytical devices (μ-PADs) through electropolymerization of molecular imprinted polyaniline (MPANI) in a novel Au nanoparticle (AuNP)-modified paper working electrode (Au-PWE). This is fabricated through the growth of an AuNP layer on the surfaces of cellulose fibers in the PWE. Under visible light irradiation, MPANI can generate the photoelectric transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), delivering the excited electrons to the AuNPs, and then to the carbon working electrode. Simultaneously, it is believed that a positively charged hole of MPANI that took part in the oxidation process was consumed by ascorbic acid (AA) to promote the amplifying photocurrent response. On the basis of this novel MPANI-Au-PWE and the principle of origami, a microfluidic molecular imprinted polymer (MIP)-based photoelectrochemical analytical origami device (μ-MPECOD), comprised of an auxiliary tab and a sample tab, is developed for the detection of heptachlor in the linear range from 0.03 nmol L(-1) to 10.0 nmol L(-1) with a low detection limit of 8.0 pmol L(-1). The selectivity, reproducibility, and stability of this μ-MPECOD are investigated. This μ-MPECOD would provide a new platform for high-throughput, sensitive, specific, and multiplex assay in public health, environmental monitoring, and the developing world. PMID:23801374

  19. Effect of inserted Si p-n junction on GaN-based photo-electrochemical CO2 conversion system

    NASA Astrophysics Data System (ADS)

    Yotsuhashi, Satoshi; Deguchi, Masahiro; Yamada, Yuka; Ohkawa, Kazuhiro

    2014-06-01

    We report on significantly improved GaN-based photo-electrochemical CO2 reduction system by inserting Si p-n junction. The device is introduced so as to raise the cathode potential which changes the reaction products qualitatively. It is discussed that the balance between cathode and anode reactions is essential to take the advantage of introduced device. We succeed in stoichiometric evaluation of oxygen evolution on the surface of GaN photo-electrode. When the reaction condition is optimized, we can realize the raised cathode potential, in which the chief reaction product of CO2 reduction changes from formic acid to hydrocarbons, such as methane (CH4) and ethylene (C2H4).

  20. Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

    NASA Astrophysics Data System (ADS)

    Maabong, Kelebogile; Machatine, Augusto G.; Hu, Yelin; Braun, Artur; Nambala, Fred J.; Diale, Mmantsae

    2016-01-01

    Hematite (α-Fe2O3) is a promising semiconductor as photoanode in solar hydrogen production from photoelectrolysis of water due to its appropriate band gap, low cost and high electrochemical stability in aqueous caustic electrolytes. Operation of such photoanode in a biased photoelectrochemical cell constitutes an anodization with consequent redox reactions at the electrode surface. α-Fe2O3 thin film photoanodes were prepared by simple and inexpensive dip coating method on fluorine doped tin oxide (FTO) glass substrate, annealed in air at 500 °C for 2 h, then electrochemically oxidized (anodized) in 1 M KOH at 500 mV for 1 min in dark and light conditions. Changes in structural properties and morphology of α-Fe2O3 nanoparticles films were investigated by XRD, Raman spectroscopy and a high resolution FE-SEM. The average grain size was observed to increase from ~57 nm for pristine samples to 73 and 77 nm for anodized samples in dark and light respectively. Broadening and red shift in Raman spectra in anodized samples may be attributed to lattice expansion upon oxidation. The UV-visible measurements revealed enhanced absorption in the photoanodes after the treatment. The findings suggest that the anodization of the photoelectrode in a biased cell causes not only changes of the molecular structure at the surface, but also changes in the crystallographic structure which can be detected with x-ray diffractometry.

  1. 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.

  2. 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.

  3. TiO2 Nanorod Arrays Sensitized with CdS Quantum Dots for Solar Cell Applications: Effects of Rod Geometry on Photoelectrochemical Performance

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Song, Bin; Zhao, Gaoling; Dong, Weixia; Han, Gaorong

    2012-05-01

    CdS quantum dot (QD) sensitized TiO2 nanorod array (NRA) film electrodes with different rod geometries were fabricated via a solvothermal route followed by a sequentialchemical bath deposition (S-CBD) process. By controlling the solution growth conditions, the rod geometries, especially the tip structures, of the TiO2 NRAs were tuned. The results indicated that the vertically aligned hierarchical NRAs possessed conically shaped tip geometry, which was favorable for film electrodes due to the reduced reflectance, enhanced light harvesting, fast charge-carrier separation and transfer, suppression of carrier recombination, sufficient electrolyte penetration and subsequent efficient QD assembly. CdS QD sensitized TiO2 NRA film electrodes with tapered tips exhibited an enhanced photoelectrochemical (PEC) performance, a photocurrent intensity of 5.13 mA/cm2 at a potential of 0 V vs. saturated calomel electrode, an open-circuit potential of -0.68 V vs. saturated calomel electrode and an incident photon to current conversion efficiency (IPCE) of 22% in the visible-light region from 400 to 500 nm. The effects of rod geometry on the optical absorption, reflectance, hydrophilic properties and PEC performance of bare TiO2 and CdS QD sensitized TiO2 NRA film electrodes were investigated. The mechanism of charge-carrier generation and transfer in these CdS QD sensitized solar cells based on vertically aligned TiO2 nanorods is discussed.

  4. BiOI/TiO2-nanorod array heterojunction solar cell: Growth, charge transport kinetics and photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Wang, Lingyun; Daoud, Walid A.

    2015-01-01

    A series of BiOI/TiO2-nanorod array photoanodes were grown on fluorine-doped tin oxide (FTO) glass using a simple two-step solvothermal/hydrothermal method. The effects of the hydrothermal process, such as TiO2 nanorod growth time, BiOI concentration and the role of surfactant, polyvinylpyrrolidone (PVP), on the growth of BiOI, were investigated. The heterojunctions were characterized by X-ray diffraction, UV-vis absorbance spectroscopy and scanning electron microscopy. The photoelectrochemical properties of the as-grown junctions, such as linear sweep voltammetry (LSV) behavior, photocurrent response and incident photon-to-electron conversion efficiency (IPCE) under Xenon lamp illumination, are presented. The cell with BiOI/TiO2 (PVP) as photoanode can reach a short current density (Jsc) of 0.13 mA/cm2 and open circuit voltage (Voc) of 0.46 V vs. Ag/AgCl under the irradiation of a 300 W Xenon lamp. Compared to bare TiO2, the IPCE of BiOI/TiO2 (PVP) increased 4-5 times at 380 nm. Furthermore, the charge transport kinetics within the heterojunction is also discussed.

  5. 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

  6. 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.

  7. 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

  8. Photoelectrochemical biosensing platform for microRNA detection based on in situ producing electron donor from apoferritin-encapsulated ascorbic acid.

    PubMed

    Yin, Huanshun; Wang, Mo; Zhou, Yunlei; Zhang, Xiaoyan; Sun, Bing; Wang, Guihua; Ai, Shiyun

    2014-03-15

    A novel signal "on" type of photoelectrochemical biosensor for microRNA-21 hybridization detection was fabricated, where Bi2S3 nanorods were used as photoactive material with a maximum adsorption at 450 nm visible light, hairpin-structure DNA as detecting probe, streptavidin as signal capturing unit and biotin functionalized ascorbic acid loaded apoferritin as signal amplification unit. Hybridization between the probe and the target microRNA-21 was confirmed by the increased photocurrent of the biosensor after electron donor of ascorbic acid was introduced into the detection buffer by digesting the apoferritin by trypsase, indicating that this method could be used fProd. Type: FTPor quantitative measurements, and the discrimination of the complementary from mismatched microRNA-21. Under the optimal detection conditions, the photoelectrochemical biosensor displayed a linear range of 1-5000 fM and a low detection limit of 0.35 fM for microRNA-21 determination. Moreover, the down-regulated expression of microRNA-21 in poultry cells and tissues infecting with avian leukosis viruses was confirmed by directly detecting microRNA-21 in extracted total RNA. This proposed strategy may open a new avenue for the applications of photoelectrochemical biosensor for oligonucleotides detection using visible light irradiation, which could largely reduce the destructive effect of UV light on biomolecules. PMID:24140833

  9. 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

  10. Quantitative photoelectrochemical detection of biological affinity reaction: biotin-avidin interaction.

    PubMed

    Dong, Dong; Zheng, Dong; Wang, Fu-Quan; Yang, Xi-Qiang; Wang, Na; Li, Yuan-Guang; Guo, Liang-Hong; Cheng, Jing

    2004-01-15

    Quantitative detection of a biological affinity reaction, the biotin/avidin recognition, was achieved using our newly developed photoelectrochemical analytical system. The system is based on the operation mechanism of the well-developed dye-sensitized photoelectrochemical solar cells and comprises a ruthenium tris(2,2'-bipyridine) (Ru-bipy) derivative as the photoelectrochemical signal-generating molecule, oxalate as the sacrificial electron donor, and tin oxide nanoparticle as the semiconductor electrode material. To perform the affinity reaction, avidin was immobilized on SnO(2) electrode by passive adsorption. Biotin-linked bovine serum albumin (BSA) was labeled with an NHS-ester derivative of Ru-bipy. After binding of BSA to the surface-immobilized avidin through biotin, photoelectrochemical measurement was carried out in the presence of oxalate. Anodic photocurrent was turned on and off repeatedly by control of incidental light. The action spectrum of the photocurrent resembled the absorption spectrum of Ru-bipy, proving the photocurrent was generated from the metal complex. A linear relationship between photocurrent and BSA concentration was obtained in the range of 1-100 microg/mL. This is the first case of quantitative photoelectrochemical detection of a biological affinity interaction. PMID:14719905

  11. An ultrasensitive label-free immunosensor based on CdS sensitized Fe-TiO2 with high visible-light photoelectrochemical activity.

    PubMed

    Fan, Dawei; Wu, Dan; Cui, Jiali; Chen, Yucheng; Ma, Hongmin; Liu, Yixin; Wei, Qin; Du, Bin

    2015-12-15

    An ultrasensitive label-free immunosensor was developed for the detection of squamous cell carcinoma antigen (SCCA) based on CdS sensitized Fe-TiO2 nanocomposites with high visible-light photoelectrochemical (PEC) activity. In this protocol, ascorbic acid was used as an efficient electron donor for scavenging photogenerated holes. The Fe-doped TiO2 improved the absorption of TiO2 in the visible light region and promoted the photocurrent production distinctly. Especially, 0.1% Fe-TiO2 showed the highest photocurrent, which was 7.4 times that of pure TiO2. Carboxyl functionalized CdS nanoparticles (CdS NPs) were bonded onto Fe-TiO2 composite through interactions between carboxyl groups and TiO2, which further enhanced the PEC signal strength by approximately 2.9 fold compared with 0.1% Fe-TiO2. The specific binding between SCCA and antibody resulted in a decrease in photocurrent intensity and the intensity decreased linearly with the logarithm of SCCA concentration in the range of 0.001-75 ng mL(-1) with a detection limit of 0.22 pg mL(-1). The developed CdS enhanced Fe-TiO2 PEC immunosensor exhibited high sensitivity, good reproducibility, and low cost, which may have potential applications in clinical diagnosis of cancers, aptasensors, photocatalysis, and other related fields. PMID:26233640

  12. Platelike WO3 sensitized with CdS quantum dots heterostructures for photoelectrochemical dynamic sensing of H2O2 based on enzymatic etching.

    PubMed

    Wang, Yanhu; Gao, Chaomin; Ge, Shenguang; Yu, Jinghua; Yan, Mei

    2016-11-15

    A platelike tungsten trioxide (WO3) sensitized with CdS quantum dots (QDs) heterojunction is developed for solar-driven, real-time, and selective photoelectrochemical (PEC) sensing of H2O2 in the living cells. The structure is synthesized by hydrothermally growing platelike WO3 on fluorine doped tin oxide (FTO) and subsequently sensitized with CdS QDs. The as-prepared WO3-CdS QDs heterojunction achieve significant photocurrent enhancement, which is remarkably beneficial for light absorption and charge carrier separation. Based on the enzymatic etching of CdS QDs enables the activation of quenching the charge transfer efficiency, thus leading to sensitive PEC recording of H2O2 level in buffer and cellular environments. The results indicated that the proposed method will pave the way for the development of excellent PEC sensing platform with the quantum dot sensitization. This study could also provide a new train of thought on designing of self-operating photoanode in PEC sensing, promoting the application of semiconductor nanomaterials in photoelectrochemistry. PMID:27179135

  13. 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

  14. Biomolecule-free, selective detection of o-diphenol and its derivatives with WS2/TiO2-based photoelectrochemical platform.

    PubMed

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

    2015-01-01

    Herein, a novel photoelectrochemical platform with WS2/TiO2 composites as optoelectronic materials was designed for selective detection of o-diphenol and its derivatives without any biomolecule auxiliary. First, catechol was chosen as a model compound for the discrimination from resorcinol and hydroquinone; then several o-diphenol derivatives such as dopamine, caffeic acid, and catechin were also detected by employing this proposed photoelectrochemical sensor. Finally, the mechanism of such a selective detection has been elaborately explored. The excellent selectivity and high sensitivity should be attributed to two aspects: (i) chelate effect of adjacent double oxygen atoms in the o-diphenol with the Ti(IV) surface site to form a five/six-atom ring structure, which is considered as the key point for distinction and selective detection. (ii) This selected WS2/TiO2 composites with proper band level between WS2 and TiO2, which could make the photogenerated electron and hole easily separated and results in great improvement of sensitivity. By employing such a photoelectrochemical platform, practical samples including commercial clinic drugs and human urine samples have been successfully performed for dopamine detection. This biomolecule-free WS2/TiO2 based photoelectrochemical platform demonstrates excellent stability, reproducibility, remarkably convenient, and cost-effective advantages, as well as low detection limit (e.g., 0.32 μmol L(-1) for dopamine). It holds great promise to be applied for detection of o-diphenol kind species in environment and food fields. PMID:25844499

  15. 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. PMID:26301999

  16. 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. PMID:23427799

  17. A novel multi-amplification photoelectrochemical immunoassay based on copper(II) enhanced polythiophene sensitized graphitic carbon nitride nanosheet.

    PubMed

    Li, Rongxia; Liu, Yixin; Li, Xiaojian; Zhang, Sen; Wu, Dan; Zhang, Yong; Wei, Qin; Du, Bin

    2014-12-15

    A new sandwich photoelectrochemical (PEC) sensing strategy was proposed for the first time based on the increasing photocurrent of water-soluble polythiophene sensitized g-C3N4 nanosheet (PT-Cl/g-C3N4) in the presence of copper(II) (Cu(2+)), which was doped on the surface of titanium dioxide as labels for multi-amplification. Herein, the photoactive films of PT-Cl/g-C3N4 is employed as the photoactive antibody (Ab1) immobilization matrix for the subsequent sandwich-type antibody-antigen affinity interactions. Upon the presence of antigen (Ag), greatly enhanced photocurrent could be triggered in the PEC platform by the labels of second antibody (Ab2) of Cu(2+) doped titanium dioxide (Cu(2+)-TiO2). As a result of the multi-amplification in this Cu(2+)-TiO2 enhanced PT-Cl/g-C3N4-based PEC immunoassay, it possesses excellent analytical performance. The antigen could be detected from 0.01 pg mL(-1) to 100.0 ng mL(-1) with a detection limit of 5 fg mL(-1). This work opens up g-C3N4 nanosheet applied in PEC sensing. More importantly, the strategy of specific positive effect of Cu(2+) on the photocurrent of g-C3N4 opens an alternative horizon for PEC sensing. PMID:25037032

  18. 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

  19. 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

  20. 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

    2015-01-01

    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

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

    PubMed

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

    2016-07-21

    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. PMID:27336961

  2. CuWO4 Nanoflake Array-Based Single-Junction and Heterojunction Photoanodes for Photoelectrochemical Water Oxidation.

    PubMed

    Ye, Wen; Chen, Fengjiao; Zhao, Feipeng; Han, Na; Li, Yanguang

    2016-04-13

    Over recent years, tremendous efforts have been invested in the search and development of active and durable semiconductor materials for photoelectrochemical (PEC) water splitting, particularly for photoanodes operating under a highly oxidizing environment. CuWO4 is an emerging candidate with suitable band gap and high chemical stability. Nevertheless, its overall solar-to-electricity remains low because of the inefficient charge separation process. In this work, we demonstrate that this problem can be partly alleviated through designing three-dimensional hierarchical nanostructures. CuWO4 nanoflake arrays on conducting glass are prepared from the chemical conversion of WO3 templates. Resulting electrode materials possess large surface areas, abundant porosity and small thickness. Under illumination, our CuWO4 nanoflake array photoanodes exhibit an anodic current density of ∼0.4 mA/cm(2) at the thermodynamic potential of water splitting in pH 9.5 potassium borate buffer - the largest value among all available CuWO4-based photoanodes. In addition, we demonstrate that their performance can be further boosted to >2 mA/cm(2) by coupling with a solution-cast BiVO4 film in a heterojunction configuration. Our study unveils the great potential of nanostructured CuWO4 as the photoanode material for PEC water oxidation. PMID:27011376

  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. PMID:26122026

  4. 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.

  5. 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

  6. 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.

  7. 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. PMID:25256955

  8. Experimental and Computational Studies on the Design of Dyes for Water-splitting Dye-sensitized Photoelectrochemical Tandem Cells

    NASA Astrophysics Data System (ADS)

    Mendez-Hernandez, Dalvin D.

    Solar energy is a promising alternative for addressing the world's current and future energy requirements in a sustainable way. Because solar irradiation is intermittent, it is necessary to store this energy in the form of a fuel so it can be used when required. The light-driven splitting of water into oxygen and hydrogen (a useful chemical fuel) is a fascinating theoretical and experimental challenge that is worth pursuing because the advance of the knowledge that it implies and the availability of water and sunlight. Inspired by natural photosynthesis and building on previous work from our laboratory, this dissertation focuses on the development of water-splitting dye-sensitized photoelectrochemical tandem cells (WSDSPETCs). The design, synthesis, and characterization of high-potential porphyrins and metal-free phthalocyanines with phosphonic anchoring groups are reported. Photocurrents measured for WSDSPETCs made with some of these dyes co-adsorbed with molecular or colloidal catalysts on TiO2 electrodes are reported as well. To guide in the design of new molecules we have used computational quantum chemistry extensively. Linear correlations between calculated frontier molecular orbital energies and redox potentials were built and tested at multiple levels of theory (from semi-empirical methods to density functional theory). Strong correlations (with r2 values > 0.99) with very good predictive abilities (rmsd < 50 mV) were found when using density functional theory (DFT) combined with a continuum solvent model. DFT was also used to aid in the elucidation of the mechanism of the thermal relaxation observed for the charge-separated state of a molecular triad that mimics the photo-induced proton coupled electron transfer of the tyrosine-histidine redox relay in the reaction center of Photosystem II. It was found that the inclusion of explicit solvent molecules, hydrogen bonded to specific sites within the molecular triad, was essential to explain the observed

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. A photoelectrochemical sensor based on nickel hydroxyl-oxide modified n-silicon electrode for hydrogen peroxide detection in an alkaline solution.

    PubMed

    Li, Huaixiang; Hao, Wenlong; Hu, Jinchao; Wu, Hongyan

    2013-09-15

    A novel photoelectrochemical hydrogen peroxide (H2O2) sensor was constructed with platinum (Pt) and nickel hydroxyl-oxide (NiOOH) double layers modified n-silicon electrode (NiOOH/Pt/n-n(+)-Si). About 40nm Pt layer and about 100nm Ni layer were successively coated on the front surface of n-n(+)-Si (111) wafers by vacuum evaporating. A stable layer of NiOOH was formed through oxidation of the Ni layer on the coated silicon wafer by the electrochemical method. The surface of modified electrode was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The NiOOH/Pt/n-n(+)-Si electrode has been used for determination of H2O2 with a two-electrode cell in the absence of reference electrode by photocurrent measurement at a zero bias. The photoelectrochemical sensor showed a good linear response to H2O2 concentrations in a range from 1.0×10(-5) to 6×10(-5)M with a determination limit (S/N=3) of 2.2μM. The NiOOH/Pt/n-n(+)-Si electrode exhibited excellent reproducibility and stability. Particularly, the facile measurement requirements made this novel modified electrode promising for the development of outdoor H2O2 sensors. PMID:23584227

  17. 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

  18. Ultrasensitive photoelectrochemical immunoassay of indole-3-acetic acid based on the MPA modified CdS/RGO nanocomposites decorated ITO electrode.

    PubMed

    Sun, Bing; Chen, Lijian; Xu, Yan; Liu, Min; Yin, Huanshun; Ai, Shiyun

    2014-01-15

    A novel ultrasensitive photoelectrochemical immunosensor was fabricated based on 3-mercaptopropionic acid stabilized CdS/reduced graphene oxide (MPA-CdS/RGO) nanocomposites for indole-3-acetic acid (IAA) detection. The MPA-CdS/RGO nanocomposites were synthesized by in situ solvothermal growth of triangulated pyramidal CdS nanoparticles on the RGO sheet. 3-Mercaptopropionic acid (MPA) was employed as the modifier and bridge to immobilize the antibody. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and UV/vis spectra. The results showed that the MPA-CdS/RGO nanocomposites revealed enhanced photocurrent response due to excellent electron transport properties of RGO and the improved assembly of CdS nanoparticles onto RGO sheet with the introduction of MPA. Based on the dependence of the photocurrent decline on the concentration of IAA, the proposed photoelectrochemical immunosensor for IAA depicted a linear range from 0.1 to 1000 ng/mL with a lower detection limit (0.05 ng/mL). The high sensitivity, reproducibility and specificity of the method permitted the method suitable to be used in real samples. PMID:23954674

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. Scanning photo-electrochemical microscopy as a versatile tool to investigate dye-sensitized nano-crystalline surfaces for solar cells

    NASA Astrophysics Data System (ADS)

    Figgemeier, Egbert; Kylberg, William H.; Bozic, Biljana

    2006-04-01

    Self-assembled monolayers (SAMs) of metal complexes are a central component of functional chemical systems for energy conversion like in e.g. the dye-sensitized photoelectrochemical solar cells or photocatalytic processes at semiconductor surfaces. In this context, scanning electrochemical microscopy (SECM) under illumination is a most valuable tool for the understanding of elementary processes of such systems. SECM comprises an ultra-microelectrode (UME), which is incorporated into a 3- or 4-electrode, respectively, electrochemical setup and which can be positioned with sub-micrometer resolution in 3 dimensions relative to a substrate. In our system, we used Pt-UMEs and dye-sensitized nano-structured electrodes as substrates. The substrate can be illuminated from the backside, which resembles working conditions of solar cell arrangements. The electrolyte consists of 2-methoxypropionitrile in conjunction with redox couples as they are used in dye-sensitized nano-structured solar cell. With this setup the photoelectrochemistry in close contact to the substrate surface initiated by the injection of electrons from the dye into the conduction band of the TiO II due to illumination at working conditions has been investigated. In this contribution we present the general principle of the method as well as an initial validation by relating photocurrents measured with the SECM and solar cell performances.

  5. Plasmon enhanced photoelectrochemical sensing of mercury (II) ions in human serum based on Au@Ag nanorods modified TiO2 nanosheets film.

    PubMed

    Zhang, Yong; Shoaib, Anwer; Li, Jiaojiao; Ji, Muwei; Liu, Jiajia; Xu, Meng; Tong, Bin; Zhang, Jiatao; Wei, Qin

    2016-05-15

    Taking advantages of the monodisperse TiO2 nanosheets (NSs) with high active crystal face exposure and the tunable localized surface plasmon resonance (LSPR) properties of Au@Ag nanorods (NRs), this study demonstrated that TiO2 NSs film with trace amount of Au@Ag NRs modification possess a strong enhancement of photocurrent response, which was remarkably inhibited with the addition of mercury (II) ions (Hg(2+)). Based on the selective decrease of photocurrent with the addition of Hg(2+), a simple photoelectrochemical (PEC) sensor has been assembled. The PEC sensor exhibits wide linear range (0.01-10nM), low detection limit (2.5pM), satisfying selectivity, reproducibility and acceptable stability for Hg(2+) detection. The feasibility of this method for practical application in human serum has been evaluated and the result was satisfactory. This PEC sensing method would provide a potential application for Hg(2+) detection in clinical diagnosis. PMID:26785311

  6. 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.

  7. 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

  8. 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

  9. Wavelength-resolved simultaneous photoelectrochemical bifunctional sensor on single interface: A newly in vitro approach for multiplexed DNA monitoring in cancer cells.

    PubMed

    Zheng, Yingning; Liang, Wenbin; Yuan, Yali; Xiong, Chengyi; Xie, Shunbi; Wang, Haijun; Chai, Yaqin; Yuan, Ruo

    2016-07-15

    Currently, the photoelectrochemical (PEC) strategies can just achieve single analyte detection on a single interface with limited detection efficiency. It is highly valuable but full of challenge to develop a PEC biosensor for multiple analytes evaluation on a single interface. For this point, the wavelength-selective photoactive materials, which could generate separated photocurrents under excitation lights with certain wavelengths, were mainly important to overcome this challenge. Herein, these wavelength-selective photoactive materials were successfully synthesized and served as signal indicators to construct a novel PEC biosensor for multiple analytes evaluation on a single interface for the first time. Moreover, an enzyme-assisted target recycling amplification strategy was introduced for ultrasensitive monitoring. As a result, the proposed PEC biosensor showed excellent analytical performance for both oral cancer (ORVOA 1) gene and p53 gene down to attomolar level. In addition, the fabricated PEC biosensor was employed to evaluate ORVOA 1 gene and p53 gene in Hela cells. This assay has laid the foundation for fabrication of simple, ultrasensitive and economical PEC diagnostic devices to detect multiple analytes in cells, which paved a new avenue for early diagnosis of cancer with higher efficiency and accuracy. PMID:27003607

  10. P3HT:PCBM:pentacene inverted polymer solar cells with roughened Al-doped ZnO nanorod array and photoelectrochemical treatment

    NASA Astrophysics Data System (ADS)

    Lee, Hsin-Ying; Huang, Hung-Lin

    2014-05-01

    In this work, the P3HT:PCBM:pentacene (1:0.8:0.065 by weight) inverted polymer solar cells with roughened Aldoped ZnO (AZO) nanorod array were fabricated. The pentacene doping could modulate the hole mobility and the electron mobility in the active layer. The optimal hole-electron mobility balance ( µh/ µe=1.000) was achieved as the pentacene doping ratio of 0.065. The 100-nm-long AZO nanorod array were formed as the carrier collection layer and the carrier transportation layer of the inverted polymer solar cells using the combination techniques of the laser interference photolithography method and the wet etching process. Because the AZO nanorod array was prepared using the wet etching process, more defects were formed on the sidewall surface of the AZO nanorods. In this work, the photoelectrochemical (PEC) method was used to grow Zn(OH)2 and Al(OH)3 thin layer on the sidewall surface of the AZO nanorods, which could reduce the carrier recombination path in the inverted polymer solar cells. Compared with the P3HT:PCBM:pentacene (1:0.8:0.065) inverted polymer solar cells without PEC treatment, the short circuit current density and the power conversion efficiency of the inverted polymer solar cells with PEC treatment were increased from 14.56 mA/cm2 to 15.85 mA/cm2 and from 5.45% to 6.13%, respectively. The enhancement in the performance of the inverted polymer solar cells with PEC treatment could be attributed to that the PEC treatment could effectively passivate the defects on the surface of the AZO nonorods.

  11. Enhanced photoelectrochemical aptasensing platform based on exciton energy transfer between CdSeTe alloyed quantum dots and SiO2@Au nanocomposites.

    PubMed

    Fan, Gao-Chao; Zhu, Hua; Shen, Qingming; Han, Li; Zhao, Ming; Zhang, Jian-Rong; Zhu, Jun-Jie

    2015-04-25

    High-efficient exciton energy transfer between CdSeTe alloyed quantum dots and SiO2@Au nanocomposites was applied to develop an enhanced photoelectrochemical aptasensing platform with ultrahigh sensitivity, good selectivity, reproducibility and stability. PMID:25804131

  12. "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

  13. 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. PMID:27414977

  14. 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.

  15. Using graphene-based plasmonic nanocomposites to quench energy from quantum dots for signal-on photoelectrochemical aptasensing.

    PubMed

    Zeng, Xianxiang; Ma, Shishi; Bao, Jianchun; Tu, Wenwen; Dai, Zhihui

    2013-12-17

    On the basis of the absorption and emission spectra overlap, an enhanced resonance energy transfer caused by excition-plasmon resonance between reduced graphene oxide (RGO)-Au nanoparticles (AuNPs) and CdTe quantum dots (QDs) was obtained. With the synergy of AuNPs and RGO as a planelike energy acceptor, it resulted in the enhancement of energy transfer between excited CdTe QDs and RGO-AuNPs nanocomposites. Upon the novel sandwichlike structure formed via DNA hybridization, the exciton produced in CdTe QDs was annihilated. A damped photocurrent was obtained, which was acted as the background signal for the development of a universal photoelectrochemical (PEC) platform. With the use of carcinoembryonic antigen (CEA) as a model which bonded to its specific aptamer and destroyed the sandwichlike structure, the energy transfer efficiency was lowered, leading to PEC response augment. Thus a signal-on PEC aptasensor was constructed. Under 470 nm irradiation at -0.05 V, the PEC aptasensor for CEA determination exhibited a linear range from 0.001 to 2.0 ng mL(-1) with a detection limit of 0.47 pg mL(-1) at a signal-to-noise ratio of 3 and was satisfactory for clinical sample detection. Since different aptamers can specifically bind to different target molecules, the designed strategy has an expansive application for the construction of versatile PEC platforms. PMID:24256069

  16. A network signal amplification strategy of ultrasensitive photoelectrochemical immunosensing carcinoembryonic antigen based on CdSe/melamine network as label.

    PubMed

    Li, Jiaojiao; Zhang, Yong; Kuang, Xuan; Wang, Zhiling; Wei, Qin

    2016-11-15

    Taking advantage of CdSe/melamine network as label and Au-TiO2 as substrate, this work developed a novel kind of signal amplification strategy for fabricating photoelectrochemical (PEC) immunoassay. The melamine, a star-shaped triamino molecule, was firstly used for readily capturing CdSe QDs and forming a CdSe/melamine network, which was formed through strong interactions between the carboxyl groups of TGA-stabilized CdSe QDs and the three amino groups of each melamine molecule. In this strategy, the primary antibody (Ab1) was immobilized onto Au-TiO2 substrate, which made the photoelectric conversion efficiency increase significantly. After the formed Ab2-CdSe/melamine network labels were captured onto the electrode surface via the specific antibody-antigen interaction, the photoelectric activity could be further enhanced via the interaction between the Au-TiO2 substrate and CdSe/melamine network. Due to this amplification of PEC signals and the special structure of the label, the fabricated PEC immunosensor was applied for sensitive and specific detection of cancer biomarker carcinoembryonic antigen (CEA), and displayed a wide linear range (0.005-1000ngmL(-1)) and low detection limit (5pgmL(-1)). In addition, the immunosensor was performed with good stability and reproducibility, and the results to analyze human serum samples were satisfactory. PMID:27281106

  17. Fluorescence and photoelectrochemical behavior of chlorophyll {ital a} adsorbed on a nanocrystalline SnO{sub 2} film

    SciTech Connect

    Bedja, I.; Kamat, P.V.; Hotchandani, S.

    1996-10-01

    Fluorescence and photoelectrochemical studies of chlorophyll {ital a} (Chl {ital a}) adsorbed on nanocrystalline SnO{sub 2} film were carried out. The results of fluorescence and incident photon to current conversion efficiency (IPCE) as a function of applied bias suggest that the fluorescence quenching and the photocarrier generation are interrelated. Fluorescence quenching has thus been utilized to determine the photogeneration efficiency, {eta}({ital e}), of charges in a SnO{sub 2}/Chl {ital a} based photoelectrochemical cell. A value of 0.75 was obtained for {eta}({ital e}) for unbiased cells. With an IPCE of 13{percent}, {eta}({ital e}) of 75{percent}, and a light harvesting efficiency of 70{percent}, the charge collection efficiency of {approximately}23{percent} was evaluated. These results suggest that the losses due to the charge recombination are a major factor that limit the efficiency of the cells. {copyright} {ital 1996 American Institute of Physics.}

  18. Micro-Square-Array InGaN-Based Light-Emitting Diode with an Insulated Ga2O3 Layer through a Photoelectrochemical Process

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Feng; Lin, Chun-Min; Jiang, Ren-Hao

    2012-01-01

    InGaN-based micro-square-array light emitting diode (MSA-LED) was fabricated by filling with an insulated Ga2O3 layer around the individual micro-square patterns for a metal interconnected process. The Ga2O3 layer formed at the mesa sidewall and the bottom etched surface of the n-type GaN layer in the LED structure through a selective photoelectrochemical (PEC) wet oxidation process in H2O solution. The 25- and 15-µm-square mesa patterns of the MSA-LED structures were defined by the plasma dry and the PEC wet etching processes that a conventional broad-area LED (BA-LED) was closed to the MSA-LED for comparison. The peak wavelength blueshift of the electroluminescence spectra and the enhancement of the light output power were measured at 1.0 nm/41% and 2.5 nm/22% for the 25- and 15-µm-MSA-LED, respectively, compared with the BA-LED. The reverse leakage current of both MSA-LED structures was about 2.5×10-11 A that was lower than the BA-LED (8.3×10-9 A) at -5 V reverse bias. The PEC Ga2O3 layer acted a passivation layer to prevent the leakage current from the mesa sidewall surface and an interconnect process in the MSA-LED structures.

  19. Novel WO3/Sb2S3 Heterojunction Photocatalyst Based on WO3 of Different Morphologies for Enhanced Efficiency in Photoelectrochemical Water Splitting.

    PubMed

    Zhang, Jing; Liu, Zhihua; Liu, Zhifeng

    2016-04-20

    We report the fabrication of tungsten trioxide (WO3) with different morphologies applied in photoelectrochemical (PEC) water splitting. The antimony sulfide (Sb2S3) was incorporated onto WO3 for the first time with the aim of improving its photoelectrocatalytic activity under visible-light illumination. In the present work, WO3 of different morphologies were fabricated on FTO glass via adjusting the pH value via a facile hydrothermal method and the morphological effect on the photoelectrocatalytic activity of the obtained samples has been discussed. WO3/Sb2S3 heterojunction photoelectrocatalysts were subsequently synthesized successfully to further improve the photoelectrocatalytic activity. Among them, WO3/Sb2S3 heterojunction photoelectrocatalyst based on WO3 micro crystals achieved an enhanced photocurrent of 1.79 mA/cm(2) at 0.8 V versus RHE under simulated sunlight, compared to 0.45 mA/cm(2) of pristine WO3 micro crystals. This excellent PEC performance benefits from the enhanced light absorbance, construction of suitable energy band gap, the improved photogenerated electron-hole pairs separation and transfer efficiency, which potentially provides new insights into PEC water splitting systems. PMID:27032422

  20. 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

  1. 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

  2. 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

  3. 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

  4. Photoelectrochemical aptasensor for the sensitive and selective detection of kanamycin based on Au nanoparticle functionalized self-doped TiO2 nanotube arrays.

    PubMed

    Xin, Yanmei; Li, Zhenzhen; Zhang, Zhonghai

    2015-11-01

    In this communication, a new photoelectrochemical aptasensor with Au nanoparticle functionalized self-doped TiO2 nanotube arrays (Au/SD-TiO2 NTs) as the core sensing unit and aptamers as the recognition unit was set up to accomplish the sensitive and selective detection of kanamycin with the lowest detection limit of 0.1 nM. PMID:26382019

  5. A novel photoelectrochemical sensor based on PPIX-functionalized WO3-rGO nanohybrid-decorated ITO electrode for detecting cysteine.

    PubMed

    Sun, Bing; Zhang, Kun; Chen, Lijian; Guo, Lintong; Ai, Shiyun

    2013-06-15

    A universal photoelectrochemical (PEC) sensing platform was fabricated based on the composition of protoporphyrin IX (PPIX), tungsten trioxide (WO3) and reduced graphene oxide (rGO) on indium tin oxide (ITO) electrode for detecting cysteine in aqueous solution. The rGO layer was not only providing bridges for the ITO electrode to anchor tightly with the WO3 nanostructures, but behaved as an electron transfer medium to enhance the electron transport from the conduction band (CB) of WO3. Furthermore, the strong absorption coefficient of porphyrin adsorbed onto WO3 nanoplates by bidentate binding could significantly improve the photocurrent density and slow charge recombination kinetics through the ultrafast electron injection. The SEM, XRD, and DRS were employed to characterize the prepared nanomaterials and modified-ITO electrodes. The results showed that the PPIX-WO3-rGO/ITO electrode could render the capability of absorbing a broad UV-vis light and displayed excellent photocurrent response in 0.1M pH 7.0 PBS with excitation wavelength at 380 nm, which could be notably improved upon addition of cysteine at 0.3 V. Based on the enhanced photocurrent signal, a novel method for PEC detection of cysteine was developed with a linear range of 0.1 to 100 μM in 0.1M PBS (pH 7.0). The detection limit was 25 nM (3σ). And higher stability and selectivity were obtained. The novel strategy could provide a fast and sensitive method for cysteine analysis. PMID:23391706

  6. Biphasic photoelectrochemical sensing strategy based on in situ formation of CdS quantum dots for highly sensitive detection of acetylcholinesterase activity and inhibition.

    PubMed

    Hou, Ting; Zhang, Lianfang; Sun, Xinzhi; Li, Feng

    2016-01-15

    Herein, we reported a facile and highly sensitive biphasic photoelectrochemical (PEC) sensing strategy based on enzymatic product-mediated in situ formation of CdS quantum dots (QDs), and assayed the activity and inhibition of acetylcholinesterase (AChE) in its optimal state. Upon the hydrolysis of acetylthiocholine catalyzed by AChE, the product thiocholine stabilizes the in situ formation of CdS QDs in homogenous solution. Due to the electrostatic attraction, the resulting tertiary amino group-functionalized CdS QDs are attached to the surface of the negatively charged indium tin oxide (ITO) electrode, generating significant PEC response upon illumination in the presence of electron donors. By taking full advantage of the in situ formation of CdS QDs in homogenous solution, this strategy is capable of detecting AChE activity and inhibition in its optimal state. A directly measured detection limit of 0.01mU/mL for AChE activity is obtained, which is superior to those obtained by some fluorescence methods. The inhibition of AChE activity by aldicarb is successfully detected, and the corresponding IC50 is determined to be 13μg/L. In addition to high sensitivity and good selectivity, this strategy also exhibits additional advantages of simplicity, low cost and easy operation. To the best of our knowledge, the as-proposed strategy is the first example demonstrating the application of CdS QDs formed in situ for biphasic PEC detection of enzyme activity and inhibition. More significantly, it opens up a new horizon for the development of homogenous PEC sensing platforms, and has great potential in probing many other analytes. PMID:26339933

  7. Highly Sensitive and Selective Photoelectrochemical Biosensor for Hg(2+) Detection Based on Dual Signal Amplification by Exciton Energy Transfer Coupled with Sensitization Effect.

    PubMed

    Zhao, Ming; Fan, Gao-Chao; Chen, Jing-Jia; Shi, Jian-Jun; Zhu, Jun-Jie

    2015-12-15

    A highly sensitive and selective photoelectrochemical (PEC) biosensor for Hg(2+) detection was developed on the basis of the synergistic effect of exciton energy transfer (EET) between CdS quantum dots (QDs) and Au nanoparticles (NPs) coupled with sensitization of rhodamine 123 (Rh123) for signal amplification. First, the TiO2/CdS hybrid structure obtained by depositing CdS QDs on TiO2 film was employed as a matrix for immobilizing probe DNA (pDNA). Next, Rh123 was introduced into the pDNA terminal, and then Au NP labeled target DNA (Au-tDNA) was hybridized with pDNA to form a rod-like double helix structure. The detection of Hg(2+) was based on a conformational change of the pDNA after incubating with Hg(2+). In the absence of Hg(2+), Rh123 was located away from the electrode surface due to the DNA hybridization, leading to inhibition of the sensitization effect, and meanwhile, the occurrence of EET between CdS QDs and Au NPs resulted in a photocurrent decrease. However, after incubating with Hg(2+), the rod-like double helix was disrupted, and the energy transfer was broken. In this case, the photocurrent recovered, and meanwhile, the folded pDNA made the labeled Rh123 move closer to the electrode surface, leading to the formation of the sensitization structure, which evidently increased the photocurrent intensity. The sensitivity of the biosensor for Hg(2+) detection was greatly enhanced for the dual signal amplification strategy. The linear range was 10 fM to 200 nM, with a detection limit of 3.3 fM. This biosensor provides a promising new platform for detecting various heavy metal ions at ultralow levels. PMID:26599580

  8. Nanostructured hematite for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Ling, Yichuan

    Solar water splitting is an environmentally friendly reaction of producing hydrogen gas. Since Honda and Fujishima first demonstrated solar water splitting in 1972 by using semiconductor titanium dioxide (TiO2) as photoanode in a photoelectrochemical (PEC) cell, extensive efforts have been invested into improving the solar-to-hydrogen (STH) conversion efficiency and lower the production cost of photoelectrochemical devices. In the last few years, hematite (alpha-Fe2O3) nanostructures have been extensively studied as photoanodes for PEC water splitting. Although nanostructured hematite can improve its photoelectrochemical water splitting performance to some extent, by increasing active sites for water oxidation and shortening photogenerated hole path length to semiconductor/electrolyte interface, the photoactivity of pristine hematite nanostructures is still limited by a number of factors, such as poor electrical conductivities and slow oxygen evolution reaction kinetics. Previous studies have shown that tin (Sn) as an n-type dopant can substantially enhance the photoactivity of hematite photoanodes by modifying their optical and electrical properties. In this thesis, I will first demonstrate an unintentional Sn-doping method via high temperature annealing of hematite nanowires grown on fluorine-doped tin oxide (FTO) substrate to enhance the donor density. In addition to introducing extrinsic dopants into semiconductors, the carrier densities of hematite can also be enhanced by creating intrinsic defects. Oxygen vacancies function as shallow donors for a number of hematite. In this regard, I have investigated the influence of oxygen content on thermal decomposition of FeOOH to induce oxygen vacancies in hematite. In the end, I have studied low temperature activation of hematite nanostructures.

  9. 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.

  10. 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.

  11. 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.

  12. Reaction kinetics and product distributions in photoelectrochemical cells. Technical progress report, March 15, 1992--March 14, 1993

    SciTech Connect

    Koval, C.A.

    1992-12-01

    Hot electron reaction studies at p-InP/CH{sub 3}CN interface revealed essential/desirable features for redox systems used to investigate hot carriers in photoelectrocehmical cells. Reduction of dibromoethylbenzene (DBEB) in presence of metallocene couples is being studied using rotating rink disk electrodes of n-and p-InP disks and Pt rings. At highly doped p-InP electrodes, reduction of DBEB can be very efficient (>30%). A minielectrochemical cell was used to investigate electron transfer at nonilluminated n-WSe{sub 2}/dimethylferrocene{sup +/0} interfaces.

  13. 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.

  14. 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.

  15. Photoelectrochemical reduction of carbon dioxide using Ge doped GaN nanowire photoanodes

    NASA Astrophysics Data System (ADS)

    Wang, Yichen; AlOtaibi, Bandar; Chowdhury, Faqrul A.; Fan, Shizhao; Kibria, Md G.; Li, Lu; Li, Chao-Jun; Mi, Zetian

    2015-11-01

    We report on the direct conversion of carbon dioxide (CO2) in a photoelectrochemical cell consisting of germanium doped gallium nitride nanowire anode and copper (Cu) cathode. Various products including methane (CH4), carbon monoxide (CO), and formic acid (HCOOH) were observed under light illumination. A Faradaic efficiency of ˜10% was measured for HCOOH. Furthermore, this photoelectrochemical system showed enhanced stability for 6 h CO2 reduction reaction on low cost, large area Si substrates.

  16. 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.

  17. 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. PMID:24413305

  18. 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

  19. 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.

  20. A derivative photoelectrochemical sensing platform for herbicide acetochlor based on TiO₂-poly (3-hexylthiophene)-ionic liquid nanocomposite film modified electrodes.

    PubMed

    Jin, Dangqin; Xu, Qin; Wang, Yanjuan; Hu, Xiaoya

    2014-09-01

    Nonelectroactive acetochlor can be indirectly determined through the photocatalytical degradation of acetochlor. A derivative visible light photoelectrochemical sensor for indirect detection of the herbicide acetochlor using TiO2-poly(3-hexylthiophene)-ionic liquid nanocomposite is constructed. Poly(3-hexylthiophene) (P3HT) was synthesized via chemical oxidative polymerization with anhydrous FeCl3 as oxidant, 3-hexylthiophene as monomer, chloroform as solvent, and the functional TiO2 nanoparticles were facilely prepared by blending TiO2 nanoparticles and P3HT at room temperature ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate solution. Operational parameters, including the photolysis time, ratios of TiO2 to P3HT, bias voltage and pH of buffer solution have been optimized. Under optimal conditions, the proposed photoelectrochemical method could detect acetochlor ranging from 0.5 to 20 μmol L(-1) with a detection limit of 0.2 nmol L(-1) at a signal-to-noise ratio of 3. The assay results of acetochlor in water samples with the proposed method were in acceptable agreement with those of the gas chromatograph-mass spectrometer (GC-MS) method. The promising sensor opens a new opportunity for fast, portable, and sensitive analysis of acetochlor in environmental samples. PMID:24913872

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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)

  8. Two Electrode Collector-Generator Method for the Detection of Electrochemically or Photoelectrochemically Produced O2.

    PubMed

    Sherman, Benjamin D; Sheridan, Matthew V; Dares, Christopher J; Meyer, Thomas J

    2016-07-19

    A dual working electrode technique for the in situ production and quantification of electrochemically or photoelectrochemically produced O2 is described. This technique, termed a collector-generator cell, utilizes a transparent fluorine doped tin oxide electrode to sense O2. This setup is specifically designed for detecting O2 in dye sensitized photoelectrosynthesis cells. PMID:27341737

  9. 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.

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

    DOEpatents

    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.

  11. 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.

  12. 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

  13. A photoelectrochemical biosensor for o-aminophenol based on assembling of CdSe and DNA on TiO2 film electrode.

    PubMed

    Yan, Kai; Wang, Rui; Zhang, Jingdong

    2014-03-15

    A novel photoelectrochemical (PEC) biosensing platform was constructed by assembling CdSe quantum dots (QDs) and DNA on liquid phase deposited TiO2 (DNA-CdSe/TiO2) film electrode. The transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis indicated that CdSe QDs were homogeneously assembled on TiO2 film. The UV-visible diffuse reflectance spectra (DRS) showed that CdSe and DNA could effectively enhance the absorption of TiO2 film to visible light. The obtained electrode showed a sensitive PEC response to o-aminophenol (OAP) under visible light irradiation. Due to the interaction between DNA and OAP, the response of OAP was improved by DNA immobilized on the sensing film. Under optimized conditions, the photocurrent was linearly proportional to OAP in the concentration range from 4.0 × 10(-7) to 2.7 × 10(-5) mol L(-1), with a detection limit (3S/N) of 8.0 × 10(-8) mol L(-1). The novel strategy could provide a fast and sensitive method for OAP determination. PMID:24161564

  14. 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

  15. Fabricating photoelectrochemical aptasensor for selectively monitoring microcystin-LR residues in fish based on visible light-responsive BiOBr nanoflakes/N-doped graphene photoelectrode.

    PubMed

    Du, Xiaojiao; Jiang, Ding; Dai, Liming; Zhou, Lei; Hao, Nan; Qian, Jing; Qiu, Baijing; Wang, Kun

    2016-07-15

    The presence of microcystins in fish has been augmenting the risk of toxicity to animal and human health. Herein, a selective and sensitive method for detecting microcystin-LR (MC-LR) in fish samples by integrating the photoelectrochemical (PEC) technique and the specific recognition ability of aptamer was developed. Specifically, as an efficient PEC transducer, the BiOBr nanoflakes/N-doped graphene p-n heterojunction electrode was utilized as the aptamer immobilization platform via the π-π stacking interaction, which would be a biosensor enabling the convenient and exquisite PEC analysis. Subsequently, the PEC response of constructed aptasensor was specific binding to MC-LR. Other isoforms did not interfere with the detection process, and thus, it could be applied for the highly selective determination of MC-LR level. Under the optimized condition, the PEC signal versus the logarithm of the MC-LR concentration was in good linear relationship ranging from 0.1pM to 100nM with detection limit about 0.03pM. The constructed method was employed to analyze fish samples collected from the local supermarket. The overall analytical recovery of MC-LR in the fish matrices ranged from 97.8 to 101.6%, with relative standard deviation (RSD) of 2.52-5.14%, implying it would have great potential in farm product analysis. PMID:26963789

  16. 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.

  17. 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

  18. 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. PMID:25393151

  19. Efficient Blue-Colored Solid-State Dye-Sensitized Solar Cells: Enhanced Charge Collection by Using an in Situ Photoelectrochemically Generated Conducting Polymer Hole Conductor.

    PubMed

    Zhang, Jinbao; Vlachopoulos, Nick; Hao, Yan; Holcombe, Thomas W; Boschloo, Gerrit; Johansson, Erik M J; Grätzel, Michael; Hagfeldt, Anders

    2016-05-18

    A high power conversion efficiency (PCE) of 5.5 % was achieved by efficiently incorporating a diketopyrrolopyrrole-based dye with a conducting polymer poly(3,4-ethylenediothiophene) (PEDOT) hole-transporting material (HTM) that was formed in situ, compared with a PCE of 2.9 % for small molecular spiro-OMeTAD-based solid-state dye solar cells (sDSCs). The high PCE for PEDOT-based sDSCs is mainly attributed to the significantly enhanced charge-collection efficiency, as a result of the three-order-of-magnitude higher hole conductivity (0.53 S cm(-1) ) compared with that of the widely used low molecular weight HTM spiro-OMeTAD (3.5×10(-4)  S cm(-1) ). PMID:26919196

  20. 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.

  1. 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.

  2. 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.

  3. Nanoscale connectivity in a TiO2/CdSe quantum dots/functionalized graphene oxide nanosheets/Au nanoparticles composite for enhanced photoelectrochemical solar cell performance.

    PubMed

    Narayanan, Remya; Deepa, Melepurath; Srivastava, Avanish Kumar

    2012-01-14

    hierarchical rapid electron transfer model can be adapted to other nanostructures as well, as they can favorably impact photoelectrochemical performance. PMID:22108634

  4. 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.

  5. Optical and photoelectrochemical study of WTe2 single crystals

    NASA Astrophysics Data System (ADS)

    Desai, P. F.; Patel, D. D.; Bhavsar, D. N.; Jani, A. R.

    2013-06-01

    Single crystals of Tungsten Ditelluride (WTe2) having a layered structure grown by chemical vapor transport method using iodine as the transporting agent are studied here. The optical response of these crystals has been obtained by UV-Vis-NIR spectroscopy at room temperature. Results of optical spectra have been analyzed on the basis of three dimensional models. Photoelectrochemical (PEC) characterization of WTe 2 single crystals have been carried out. Photo response measurements were obtained at different intensities of light source to illuminate the photoanode. The effect of intensity in the efficiency of PEC solar cell has been studied. The implications of the results have been discussed.

  6. One-pot hydrothermal route to fabricate nitrogen doped graphene/Ag-TiO2: Efficient charge separation, and high-performance "on-off-on" switch system based photoelectrochemical biosensing.

    PubMed

    Jiang, Ding; Du, Xiaojiao; Chen, Danyang; Zhou, Lei; Chen, Wei; Li, Yaqi; Hao, Nan; Qian, Jing; Liu, Qian; Wang, Kun

    2016-09-15

    Charge separation is crucial for increasing the performances of semiconductor-based materials in many photoactive applications. In this paper, we designed novel nanocomposites consisting of TiO2 nanocrystals, Ag nanoparticles (NPs) and nitrogen doped graphene (NGR) via a facile one-pot hydrothermal route. The as-prepared ternary nanocomposites exhibited enhanced photoelectrochemical (PEC) performances owing to the introduction of Ag NPs and NGR, which increase the excitons' lifetime and improve the charge transfer. In particular, it is shown by means of the transient-state surface photocurrent responses that the photocurrent intensity of the as-fabricated composites exhibited 18.2 times higher than that of pristine TiO2. Based on the robust photocurrent signal, a new kind of "on-off-on" PEC aptasensor was established with the assistance of Pb(2+) aptamer, which integrates the advantages of low background signal and high sensitivity. Under optimal conditions, a wide linear response for Pb(2+) detection was obtained from 1pM to 5nM as well as a detection limit down to 0.3pM. With its simplicity, selectivity, and sensitivity, this proposed strategy shows great promise for Pb(2+) detection in food and environment analysis. PMID:27108257

  7. 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

  8. 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.

  9. A novel photoelectrochemical sensor based on photocathode of PbS quantum dots utilizing catalase mimetics of bio-bar-coded platinum nanoparticles/G-quadruplex/hemin for signal amplification.

    PubMed

    Wang, Guang-Li; Liu, Kang-Li; Shu, Jun-Xian; Gu, Tian-Tian; Wu, Xiu-Ming; Dong, Yu-Ming; Li, Zai-Jun

    2015-07-15

    Photocathode based on p-type PbS quantum dots (QDs) combing a novel signal amplification strategy utilizing catalase (CAT) mimetics was designed and utilized for sensitive photoelectrochemical (PEC) detection of DNA. The bio-bar-coded Pt nanoparticles (NPs)/G-quadruplex/hemin exhibited high CAT-like activity following the Michaelis-Menten model for decomposing H2O2 to water and oxygen, whose activity even slightly exceeded that of natural CAT. The bio-bar-code as a catalytic label was conjugated onto the surface of PbS QDs modified electrodes through the formed sandwich-type structure due to DNA hybridization. Oxygen in situ generated by the CAT mimetics of the bio-bar-code of Pt NPs/G-quadruplex/hemin acted as an efficient electron acceptor of illuminated PbS QDs, promoting charge separation and enhancing cathodic photocurrent. Under optimal conditions, the developed PEC biosensor for target DNA exhibited a dynamic range of 0.2pmol/L to 1.0nmol/L with a low detection limit of 0.08pmol/L. The high sensitivity of the method was resulted from the sensitive response of PbS QDs to oxygen and the highly efficient CAT-like catalytic activity of the bio-bar-coded Pt NPs/G-quadruplex/hemin. PMID:25723768

  10. 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