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Sample records for nanorod arrays tailored

  1. Tailoring terahertz plasmons with silver nanorod arrays

    PubMed Central

    Cao, Wei; Song, Chunyuan; Lanier, Thomas E.; Singh, Ranjan; O'Hara, John F.; Dennis, William M.; Zhao, Yiping; Zhang, Weili

    2013-01-01

    Plasmonic materials that strongly interact with light are ideal candidates for designing subwavelength photonic devices. We report on direct coupling of terahertz waves in metallic nanorods by observing the resonant transmission of surface plasmon polariton waves through lithographically patterned films of silver nanorod (100 nm in diameter) micro-hole arrays. The best enhancement in surface plasmon resonant transmission is obtained when the nanorods are perfectly aligned with the electric field direction of the linearly polarized terahertz wave. This unique polarization-dependent propagation of surface plasmons in structures fabricated from nanorod films offers promising device applications. We conclude that the anisotropy of nanoscale metallic rod arrays imparts a material anisotropy relevant at the microscale that may be utilized for the fabrication of plasmonic and metamaterial based devices for operation at terahertz frequencies.

  2. Tailoring copper oxide semiconductor nanorod arrays for photoelectrochemical reduction of carbon dioxide to methanol.

    PubMed

    Rajeshwar, Krishnan; de Tacconi, Norma R; Ghadimkhani, Ghazaleh; Chanmanee, Wilaiwan; Janáky, Csaba

    2013-07-22

    Solar photoelectrochemical reduction of carbon dioxide to methanol in aqueous media was driven on hybrid CuO/Cu2O semiconductor nanorod arrays for the first time. A two-step synthesis was designed and demonstrated for the preparation of these hybrid copper oxide one-dimensional nanostructures on copper substrates. The first step consisted in the growth of CuO nanorods by thermal oxidation of a copper foil at 400 °C. In the second step, controlled electrodeposition of p-type Cu2O crystallites on the CuO walls was performed. The resulting nanorod morphology with controllable wall thickness by adjusting the Cu2O electrodeposition time as well as their surface/bulk chemical composition were probed by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. Photoelectrosynthesis of methanol from carbon dioxide was demonstrated at -0.2 V vs SHE under simulated AM1.5 solar irradiation on optimized hybrid CuO/Cu2O nanorod electrodes and without assistance of any homogeneous catalyst (such as pyridine or imidazole) in the electrolyte. The hybrid composition, ensuring double pathway for photoelectron injection to CO2, along with high surface area were found to be crucial for efficient performance in methanol generation under solar illumination. Methanol formation, tracked by gas chromatography/mass spectrometry, indicated Faradaic efficiencies of ~95%. PMID:23712877

  3. The Silver Nanorod Array SERS Substrates

    NASA Astrophysics Data System (ADS)

    Zhao, Yiping; Liu, Yongjun

    2010-08-01

    The fabrication of large area, uniform and high enhancement substrates for surface enhanced Raman scattering (SERS) based sensing is a bottle-neck for practical applications of SERS. Recently using oblique angle deposition (OAD) method, we have fabricated silver nanorod arrays with SERS enhancement factor >108, and SERS intensity variation <14%. The SERS spectra from those substrates have been demonstrated to be able to distinguish different viruses and virus strains, bacteria, microRNAs, or other chemical and biological molecules. We have performed a detailed characterization on those Ag nanorod substrates. The SERS enhancement factor depends strongly on the nanorod length and the fabrication conditions. For different deposition angle, there is an optimal nanorod length that gives the maximum enhancement. The SERS enhancement seems to directly depend on the reflectivity of the Ag nanorod substrates at the excitation wavelength regardless of the deposition angles and rod length. The SERS performance also depends strongly on the configurations of the excitation laser beam: the incident angle, the polarization, and the reflectance of the underlayer substrates. A simple modified Greenler's model is proposed to qualitatively explain those effects. The possible origin for the high enhancement of the Ag nanorod substrates has been studied by placing the Raman probe molecules on different locations of the substrates, and we have found that the side surfaces of the nanorod arrays contributes more to the SERS enhancement compared to the ends. We propose that this is due to the anisotropic absorbance nature of the Ag nanorod substrates.

  4. Antibacterial activity of ordered gold nanorod arrays.

    PubMed

    Zhu, Yuejing; Ramasamy, Mohankandhasamy; Yi, Dong Kee

    2014-09-10

    Well-packed two- and three-dimensional (2D and 3D) gold nanorod (AuNR) arrays were fabricated using confined convective arraying techniques. The array density could be controlled by changing the concentration of the gold nanorods solution, the velocity of the moving substrate, and the environment air-temperature. The hydrophilic behavior of glass substrates before and after surface modification was studied through contact angle measurements. The affinity and alignment of the AuNR arrays with varying nanorod concentrations and the resulting different array densities were studied using field emission scanning electron microscopy (FE-SEM). Under stable laser intensity irradiation, the photothermal response of the prepared arrays was measured using a thermocouple and the results were analyzed quantitatively. Synthesized AuNR arrays were added to Escherichia coli (E. coli) suspensions and evaluated for photothermal bactericidal activity before and after laser irradiation. The results showed promising bactericidal effect. The severity of pathogen destruction was measured and quantified using fluorescence microscopy, bioatomic force microscopy (Bio-AFM) and flow cytometry techniques. These results indicated that the fabricated AuNR arrays at higher concentrations were highly capable of complete bacterial destruction by photothermal effect compared to the low concentration AuNR arrays. Subsequent laser irradiation of the AuNR arrays resulted in rapid photoheating with remarkable bactericidal activity, which could be used for water treatment to produce microbe-free water. PMID:25148531

  5. Polarization dependent, surface plasmon induced photoconductance in gold nanorod arrays

    NASA Astrophysics Data System (ADS)

    Diefenbach, S.; Erhard, N.; Schopka, J.; Martin, A.; Karnetzky, C.; Iacopino, D.; Holleitner, A. W.

    2014-03-01

    We report on the photoconductance in two-dimensional arrays of gold nanorods which is strongly enhanced at the frequency of the longitudinal surface plasmon of the nanorods. The arrays are formed by a combination of droplet deposition and stamping of gold nanorod solutions on SiO2 substrates. We find that the plasmon induced photoconductance is sensitive to the linear polarization of the exciting photons. We interpret the occurrence of the photoconductance as a bolometric enhancement of the arrays' conductance upon excitation of the longitudinal surface plasmon resonance of the nanorods.

  6. Rapid fabrication of ZnO nanorod arrays with controlled spacing by micelle-templated solvothermal growth

    NASA Astrophysics Data System (ADS)

    Pelligra, Candice I.; Toth, Kristof; Hu, Hanqiong; Osuji, Chinedum O.

    2015-12-01

    We present a facile method for the synthesis of nanorod arrays over large areas with fine control over the average rod-rod spacing. Block copolymer micelles are used to template solvothermal synthesis of ZnO nanorods by preferentially enabling reactant diffusion through the micelle cores to an underlying seed layer. The distance between nanorod centers is defined by the micelle number density which is in turn controlled by the molecular weight of the block copolymer, and the block copolymer concentration in a templating film. We demonstrate the ability to control the resulting nanorod number density from ~100 μm-2 down to ~10 μm-2 with high fidelity. Correspondingly, the distance between nanorod surfaces was varied from ~60 nm to 230 nm. The method developed here provides a viable approach for rapidly fabricating large-area nanostructured electrodes comprised of nanorod arrays with controlled geometries. The ability to tailor nanorod spacing over a broad range suggests applications in photovoltaics and sensors based on optical resonances can be readily addressed.We present a facile method for the synthesis of nanorod arrays over large areas with fine control over the average rod-rod spacing. Block copolymer micelles are used to template solvothermal synthesis of ZnO nanorods by preferentially enabling reactant diffusion through the micelle cores to an underlying seed layer. The distance between nanorod centers is defined by the micelle number density which is in turn controlled by the molecular weight of the block copolymer, and the block copolymer concentration in a templating film. We demonstrate the ability to control the resulting nanorod number density from ~100 μm-2 down to ~10 μm-2 with high fidelity. Correspondingly, the distance between nanorod surfaces was varied from ~60 nm to 230 nm. The method developed here provides a viable approach for rapidly fabricating large-area nanostructured electrodes comprised of nanorod arrays with controlled geometries

  7. Broadband resonances in indium-tin-oxide nanorod arrays

    SciTech Connect

    Li, Shi-Qiang E-mail: r-chang@northwestern.edu; Sakoda, Kazuaki; Ketterson, John B.; Chang, Robert P. H. E-mail: r-chang@northwestern.edu

    2015-07-20

    There is currently much discussion within the nanophotonics community regarding the origin of wavelength selective absorption/scattering of light by the resonances in nanorod arrays. Here, we report a study of resonances in ordered indium-tin-oxide nanorod arrays resulting from waveguide-like modes. We find that with only a 2.4% geometrical coverage, micron-length nanorod arrays interact strongly with light across a surprisingly wide band from the visible to the mid-infrared, resulting in less than 10% transmission. Simulations show excellent agreement with our experimental observations. The field profile in the vicinity of the rods obtained from simulations shows that the electric field is mainly localized on the surfaces of the nanorods for all resonances. Based on our analysis, the resonances in the visible are different in character from those in the infrared. When light is incident on the array, part of it propagates in the space between the rods and part of it is guided within the rods. The phase difference (interference) at the ends of the rods forms the basis for the resonances in the visible region. The resonances in the infrared are Fabry-Perot-like resonances involving standing surface waves between the opposing ends of the rods. Simple analytical formulae predict the spectral positions of these resonances. It is suggested that these phenomena can be utilized for wavelength-selective photodetectors, modulators, and nanorod-based solar cells.

  8. Uniform Gold Nanorod Arrays from Polyethylenimine-coated Alumina Templates

    PubMed Central

    Moon, Jeong-Mi; Wei, Alexander

    2008-01-01

    Monolithic Au nanorod arrays can be grown by electrodeposition in Au-backed nanoporous alumina templates using polyethylenimine (PEI) as an adhesion layer, with excellent height control between 300 nm and 1.4 microns. The local height distribution can be extremely narrow with relative standard deviations well below 2%. The uniform growth rate appears to be determined by the adsorbed PEI matrix, which controls the growth kinetics of the grains comprising the nanorods. The nanorods can be retained as free-standing 2D arrays after careful removal of the AAO template. Reflectance spectroscopy reveals a collective plasmon mode with a maximum near 1.2 μm, in accord with recent calculations for 2D arrays of closely spaced cylindrical nanoparticles. PMID:16375304

  9. Rapid fabrication of ZnO nanorod arrays with controlled spacing by micelle-templated solvothermal growth.

    PubMed

    Pelligra, Candice I; Toth, Kristof; Hu, Hanqiong; Osuji, Chinedum O

    2016-01-01

    We present a facile method for the synthesis of nanorod arrays over large areas with fine control over the average rod-rod spacing. Block copolymer micelles are used to template solvothermal synthesis of ZnO nanorods by preferentially enabling reactant diffusion through the micelle cores to an underlying seed layer. The distance between nanorod centers is defined by the micelle number density which is in turn controlled by the molecular weight of the block copolymer, and the block copolymer concentration in a templating film. We demonstrate the ability to control the resulting nanorod number density from ∼100 μm(-2) down to ∼10 μm(-2) with high fidelity. Correspondingly, the distance between nanorod surfaces was varied from ∼60 nm to 230 nm. The method developed here provides a viable approach for rapidly fabricating large-area nanostructured electrodes comprised of nanorod arrays with controlled geometries. The ability to tailor nanorod spacing over a broad range suggests applications in photovoltaics and sensors based on optical resonances can be readily addressed. PMID:26611402

  10. Ordered silicon nanorod arrays with controllable geometry and robust hydrophobicity

    NASA Astrophysics Data System (ADS)

    Zi-Wen, Wang; Jia-Qi, Cai; Yi-Zhi, Wu; Hui-Jie, Wang; Xiao-Liang, Xu

    2015-01-01

    Highly ordered silicon nanorod (SiNR) arrays with controllable geometry are fabricated via nanosphere lithography and metal-assisted chemical etching. It is demonstrated that the key to achieving a high-quality metal mask is to construct a non-close-packed template that can be removed with negligible damage to the mask. Hydrophobicity of SiNR arrays of different geometries is also studied. It is shown that the nanorod structures are effectively quasi-hydrophobic with a contact angle as high as 142°, which would be useful in self-cleaning nanorod-based device applications. Project supported by the National Natural Science Foundation of China (Grant No. 51272246) and the Scientific and Technological Research Foundation of Anhui Province, China (Grant No. 12010202035).

  11. Infrared spectroscopy of molecules with nanorod arrays: a numerical study.

    PubMed

    Tardieu, Clément; Vincent, Grégory; Haïdar, Riad; Collin, Stéphane

    2016-04-15

    Nanorod arrays with diameters much smaller than the wavelength exhibit sharp resonances with strong electric-field enhancement and angular dependence. They are investigated for enhanced infrared spectroscopy of molecular bonds. The molecule 3-cyanopropyldimethylchlorosilane (CS) is taken as a reference, and its complex permittivity is determined experimentally in the 3-5 μm wavelength range. When grafted on silicon nitride nanorods, we show numerically that its weak absorption bands due to chemical bond vibrations can be enhanced by several orders of magnitude compared with unstructured thin film. We propose a figure of merit (FoM) to assess the performance of this spectroscopic scheme, and we study the impact of the nanorod cross section on the FoM. PMID:27082334

  12. Magnetic behavior in an ordered Co nanorod array

    NASA Astrophysics Data System (ADS)

    Wang, T.; Wang, Y.; Fu, Y.; Hasegawa, T.; Oshima, H.; Itoh, K.; Nishio, K.; Masuda, H.; Li, F. S.; Saito, H.; Ishio, S.

    2008-11-01

    The magnetization reversal process of an ordered Co nanorod array is shown using the images obtained from successive in-field magnetic force microscope (MFM) measurements. The magnetization reversal model is discussed according to local and whole magnetization reversal properties measured by the polar magneto-optical Kerr effect (PMOKE) and an alternating gradient magnetometer (AGM), respectively. Additionally, the dipolar field was probed using in-field MFM measurements. By removing the effect of the dipolar field, an intrinsic switching field distribution (SFD) is shown in a map with a hexagonal array. A detailed study of the dipolar field in ordered nanorod arrays with various diameters and pitches was carried out by numerical calculations.

  13. Significant effects of reaction temperature on morphology, crystallinity, and photoelectrical properties of rutile TiO2 nanorod array films

    NASA Astrophysics Data System (ADS)

    Sun, Xianmiao; Sun, Qiong; Zhang, Qian; Zhu, Qianqian; Dong, Hongzhou; Dong, Lifeng

    2013-03-01

    Oriented single-crystalline TiO2 nanorod arrays have been extensively studied as the electrode of photoelectrochemical cells due to their unique properties. In this study, oriented rutile TiO2 nanorod arrays were directly synthesized on fluorine-doped tin oxide glass substrates by a facile hydrothermal method, and the effects of growth conditions (i.e. reaction temperature, growth time and titanium precursor) on their morphologies, crystal structures and photoelectrical properties were investigated. Reaction temperature played a more critical role in tailoring the surface morphology, crystal structures (i.e. length, diameter and crystallinity of nanorods) and photoelectrical properties of the nanorods than growth time did. With the increase in reaction temperature from 140 °C to 200 °C, both photocurrent density and external quantum efficiency (EQE) increased initially and then decreased, with a maximum value of 5.6 × 10-2 mA cm-2 at 170 °C and 2.7% at 160 °C, respectively. In addition, photoelectric measurements demonstrated that TiO2 nanorod arrays synthesized from TiCl4 at a relatively low reaction temperature exhibited a much higher EQE value than those obtained from titanium isopropoxide.

  14. Al-doped ZnO aligned nanorod arrays for opto-electronic and sensor applications

    NASA Astrophysics Data System (ADS)

    Holloway, T.; Mundle, R.; Dondapati, H.; Konda, R. B.; Bahoura, M.; Pradhan, A. K.

    2012-04-01

    We report on the growth of vertically aligned Al:ZnO nanorod arrays synthesized by the hydrothermal technique at considerably low temperature on a sputtered Al:ZnO seed layer. The morphology demonstrates that the nanorod arrays maintain remarkable alignment along the c-axis over a large area. The optoelectronic properties of nanorod arrays on Al:ZnO/p-Si seed layer with SiO2 have been illustrated. The photocurrent is significantly reduced in nanorod arrays on AZO/SiO2/p-Si heterojunction due to multiple scattering phenomena associated with the nanorod arrays. The optical properties of the AZO film with and without the AZO nanorod arrays were investigated. Also the effects of an intermediate layer in the AZO/P-Si heterojunction structure with and without the AZO nanorod array present were explored. All the various intermediate layers displayed photovoltaic effect behavior, especially with the AZO/SiO2/P-Si heterojunction structure, which exhibited ideal diode behavior. The optoelectronic properties of nanorod arrays on AZO/P-Si seed layer with SiO2 have been illustrated. The photocurrent is significantly reduced in nanorod arrays on AZO/SiO2/P-Si heterojunction due to multiple scattering phenomena associated with the nanorod arrays. The results have tremendous impact for sensor fabrication, including glucose sensor.

  15. Large hexagonal arrays of aligned ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Banerjee, D.; Rybczynski, J.; Huang, J. Y.; Wang, D. Z.; Kempa, K.; Ren, Z. F.

    2005-02-01

    Large-scale truly periodic arrays of vertically aligned zinc oxide nanorods were grown on pre-patterned and pre-annealed gold dots on a-plane sapphire substrates via the vapor liquid solid mechanism. Periodic arrays of triangular gold islands were first patterned on the a-plane sapphire substrates by the nanosphere self-assembly technique. Zinc has been found to be an effective interfacial modifier between gold and sapphire to form single catalytic dots from triangular islands. The successful fabrication of zinc oxide nanowires in truly periodic arrays opens up the possibility of achieving enhanced room-temperature ultraviolet lasing and photonic crystal based devices and sensors.

  16. Copper nanorod array assisted silicon waveguide polarization beam splitter.

    PubMed

    Kim, Sangsik; Qi, Minghao

    2014-04-21

    We present the design of a three-dimensional (3D) polarization beam splitter (PBS) with a copper nanorod array placed between two silicon waveguides. The localized surface plasmon resonance (LSPR) of a metal nanorod array selectively cross-couples transverse electric (TE) mode to the coupler waveguide, while transverse magnetic (TM) mode passes through the original input waveguide without coupling. An ultra-compact and broadband PBS compared to all-dielectric devices is achieved with the LSPR. The output ports of waveguides are designed to support either TM or TE mode only to enhance the extinction ratios. Compared to silver, copper is fully compatible with complementary metal-oxide-semiconductor (CMOS) technology. PMID:24787839

  17. Polycyanurate nanorod arrays for optical-waveguide-based biosensing.

    PubMed

    Gitsas, Antonis; Yameen, Basit; Lazzara, Thomas Dominic; Steinhart, Martin; Duran, Hatice; Knoll, Wolfgang

    2010-06-01

    We demonstrate high-sensitivity biosensing by optical waveguide spectroscopy (OWS) at visible wavelengths using aligned polycyanurate thermoset nanorods (PCNs) arranged in extended arrays as waveguides. The PCNs formed by thermal polymerization of a cyanate ester monomer in self-ordered nanoporous alumina templates were 60 nm in diameter and 650 nm in length. Subtle refractive index changes of the medium surrounding the nanorods could be detected by monitoring the angular shifts of waveguiding modes. The sensing figure of merit thus achieved amounted to 196 reciprocal refractive index units and is, therefore, higher than that of other sensors based on angular modulation, while the configuration used here is eligible for further surface functionalization. Kinetics of the binding of taurine to the surface cyanate groups of the PCNs was monitored by OWS. Thus, modified PCNs bearing sulfonic acid groups at their surfaces were obtained. PCN arrays may represent a versatile platform for the design of biosensors. PMID:20527931

  18. Aligned silver nanorod arrays as substrates for surface-enhanced infrared absorption spectroscopy.

    PubMed

    Leverette, C L; Jacobs, S A; Shanmukh, S; Chaney, S B; Dluhy, R A; Zhao, Y-P

    2006-08-01

    Preferentially aligned silver nanorod arrays prepared by oblique angle vapor deposition were evaluated as substrates for surface-enhanced infrared absorption (SEIRA) spectroscopy. These nanorod arrays have an irregular surface lattice and are composed of tilted, cylindrically shaped nanorods that have an average length of 868 nm +/- 95 nm and an average diameter of 99 nm +/- 29 nm. The overall enhancement factor for chemisorbed organic films of para-nitrobenzoic acid (PNBA) deposited onto the Ag nanorod arrays analyzed by external reflection SEIRA was calculated to be 31 +/- 9 compared to infrared reflection-absorption spectroscopy (IRRAS) obtained from a 500 nm Ag film substrate. This enhancement is attributed to the unique optical properties of the nanorod arrays as well as the increased surface area provided by the nanorod substrate. SEIRA reflection-absorbance intensity was observed with both p- and s-polarized incident radiation with angles of incidence ranging from 25 degrees to 80 degrees . The largest intensity was achieved with p-polarization and incident angles larger than 75 degrees . Polarization-dependent ultraviolet/visible/near-infrared (UV/Vis/NIR) spectra of the nanorod arrays demonstrate that the red-shifted surface plasmon peaks of the elongated nanorods may be partially responsible for the observed SEIRA response. The SEIRA detection limit for the Ag nanorod arrays was estimated to be 0.08 ng/cm(2). Surface-enhanced Raman scattering (SERS) and SEIRA analysis of chemisorbed PNBA utilizing the same nanorod substrate is demonstrated. PMID:16925927

  19. Aligned Silver Nanorod Array as SERS Substrates for Viral Sensing

    NASA Astrophysics Data System (ADS)

    Zhao, Yiping; Shanmukh, Saratchandra; Chaney, Stephen B.; Jones, Les; Dluhy, Richard A.; Tripp, Ralph A.

    2006-03-01

    The aligned silver nanorod array substrates prepared by the oblique angle deposition method are capable of providing extremely high enhancement factors (˜10^9) at near-infrared wavelengths (785 nm) for a standard reporter molecule 1,2 trans-(bis)pyridyl-ethene (BPE). The enhancement factor depends strongly on the length of the Ag nanorods, the substrate coating, as well as the polarization of the excitation laser beam. With the current optimum structure, we demonstrate that the detection limit for BPE can be lower than 0.1 fM. The applicability of this substrate to the detection of bioagents has been investigated by looking several viruses, such as Adenovirus, HIV, Rhinovirus and Respiratory Syncytial Virus (RSV), at low quantities (˜0.5uL). Different viruses have different fingerprint Raman spectrum. The detection of virus presented in infected cells has also been demonstrated.

  20. The study of light waveguide effects on ZnO nanorod arrays

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Un; Gang, Myeng-Gil; Kim, Jin-A.; Moon, Jong-Ha; Kim, Doo-Gun; Kim, Seon-Hoon; Ki, Hyun-Chul; Choi, Ju-hyeon; Kim, Jin-Hyeok

    2016-03-01

    Two different types of ZnO nanorods (hexagonal pyramid-shaped nanorod and hexagonal prism-shaped nanorod) were integrated on light emitting diodes (LEDs) for the investigation of light waveguide effects, which were evaluated using electroluminescence (EL) and current-voltage ( I- V) characteristics. EL intensity in LEDs with hexagonal prism-shaped ZnO nanorod arrays were improved by 18% while EL intensity in LEDs with hexagonal pyramid-shaped ZnO nanorods were reduced by 25% compared to bare LEDs. 3D-finite dimension time domain (3D-FDTD) programs were used to simulate the light waveguide effect on the two different shapes of ZnO nanorods. In addition, photonic crystals (PCs) effects in ZnO nanorod arrays were simulated to verify the light waveguide effect. It was found that light in a hexagonal prism-shaped ZnO nanorod propagated from the bottom to the top end. However, the light in a hexagonal pyramid-shaped ZnO nanorod was dissipated on the lateral face. The light extraction efficiency in ZnO nanorod arrays was dominated by the top end shape and planar density of ZnO nanorods. [Figure not available: see fulltext.

  1. Tailorable chiroptical activity of metallic nanospiral arrays

    NASA Astrophysics Data System (ADS)

    Deng, Junhong; Fu, Junxue; Ng, Jack; Huang, Zhifeng

    2016-02-01

    The engineering of the chiroptical activity of the emerging chiral metamaterial, metallic nanospirals, is in its infancy. We utilize glancing angle deposition (GLAD) to facilely sculpture the helical structure of silver nanospirals (AgNSs), so that the scope of chiroptical engineering factors is broadened to include the spiral growth of homochiral AgNSs, the combination of left- and right-handed helical chirality to create heterochiral AgNSs, and the coil-axis alignment of the heterochiral AgNSs. It leads to flexible control over the chiroptical activity of AgNS arrays with respect to the sign, resonance wavelength and amplitude of circular dichroism (CD) in the UV and visible regime. The UV chiroptical mode has a distinct response from the visible mode. Finite element simulation together with LC circuit theory illustrates that the UV irradiation is mainly adsorbed in the metal and the visible is preferentially scattered by the AgNSs, accounting for the wavelength-related chiroptical distinction. This work contributes to broadening the horizons in understanding and engineering chiroptical responses, primarily desired for developing a wide range of potential chiroplasmonic applications.The engineering of the chiroptical activity of the emerging chiral metamaterial, metallic nanospirals, is in its infancy. We utilize glancing angle deposition (GLAD) to facilely sculpture the helical structure of silver nanospirals (AgNSs), so that the scope of chiroptical engineering factors is broadened to include the spiral growth of homochiral AgNSs, the combination of left- and right-handed helical chirality to create heterochiral AgNSs, and the coil-axis alignment of the heterochiral AgNSs. It leads to flexible control over the chiroptical activity of AgNS arrays with respect to the sign, resonance wavelength and amplitude of circular dichroism (CD) in the UV and visible regime. The UV chiroptical mode has a distinct response from the visible mode. Finite element simulation

  2. Selective growth of ZnO nanorods on hydrophobic Si nanorod arrays

    NASA Astrophysics Data System (ADS)

    Lu, Ming-Yen; Wang, Ying-Jhe; Hong, Meng-Hsiang; Chiu, Cheng-Yao; You, Shuen-Jium; Lu, Ming-Pei

    2015-02-01

    In this paper we describe the selective growth of ZnO nanorods (NRs) on top of hydrophobic Si NR arrays. The periodic Si NR arrays, prepared through electroless chemical etching and HF treatment, functioned as hydrophobic substrates. Droplets containing ZnO seeds could be positioned on the Si NR arrays, causing the ZnO seeds to deposit selectively upon them, with n-ZnO NR/p-Si NR array heterojunctions ultimately forming after hydrothermal growth of ZnO NRs. Because of compensation for the difference in refractive index between air and the Si substrate, the n-ZnO NR/p-Si NR arrays exhibited excellent absorption ability in the visible range. Devices based on these n-ZnO NR/p-Si NR array heterojunctions displayed not only rectifying behavior but also photovoltaic effects when illuminated with UV light. The low temperature and low cost of this fabrication process suggest that the selective growth of n-ZnO NRs on p-Si NR arrays might allow such structures to have diverse applications in optoelectronics.

  3. Selective growth of ZnO nanorods on hydrophobic Si nanorod arrays.

    PubMed

    Lu, Ming-Yen; Wang, Ying-Jhe; Hong, Meng-Hsiang; Chiu, Cheng-Yao; You, Shuen-Jium; Lu, Ming-Pei

    2015-02-01

    In this paper we describe the selective growth of ZnO nanorods (NRs) on top of hydrophobic Si NR arrays. The periodic Si NR arrays, prepared through electroless chemical etching and HF treatment, functioned as hydrophobic substrates. Droplets containing ZnO seeds could be positioned on the Si NR arrays, causing the ZnO seeds to deposit selectively upon them, with n-ZnO NR/p-Si NR array heterojunctions ultimately forming after hydrothermal growth of ZnO NRs. Because of compensation for the difference in refractive index between air and the Si substrate, the n-ZnO NR/p-Si NR arrays exhibited excellent absorption ability in the visible range. Devices based on these n-ZnO NR/p-Si NR array heterojunctions displayed not only rectifying behavior but also photovoltaic effects when illuminated with UV light. The low temperature and low cost of this fabrication process suggest that the selective growth of n-ZnO NRs on p-Si NR arrays might allow such structures to have diverse applications in optoelectronics. PMID:25590263

  4. Templated electrodeposition and photocatalytic activity of cuprous oxide nanorod arrays.

    PubMed

    Haynes, Keith M; Perry, Collin M; Rivas, Marlene; Golden, Teresa D; Bazan, Antony; Quintana, Maria; Nesterov, Vladimir N; Berhe, Seare A; Rodríguez, Juan; Estrada, Walter; Youngblood, W Justin

    2015-01-14

    Cuprous oxide (Cu2O) nanorod arrays have been prepared via a novel templated electrodeposition process and were characterized for their photocatalytic behavior in nonaqueous photoelectrochemical cells. Zinc oxide (ZnO) nanorod films serve as sacrificial templates for the in situ formation of polymer nanopore membranes on transparent conductive oxide substrates. Nitrocellulose and poly(lactic acid) are effective membrane-forming polymers that exhibit different modes of template formation, with nitrocellulose forming conformal coatings on the ZnO surface while poly(lactic acid) acts as an amorphous pore-filling material. Robust template formation is sensitive to the seeding method used to prepare the precursor ZnO nanorod films. Photoelectrochemical cells prepared from electrodeposited Cu2O films using methyl viologen as a redox shuttle in acetonitrile electrolyte exhibit significant charge recombination that can be partially suppressed by a combination of surface passivation methods. Surface-passivated nanostructured Cu2O films show enhanced photocurrent relative to planar electrodeposited Cu2O films of similar thickness. We have obtained the highest photocurrent ever reported for electrodeposited Cu2O in a nonaqueous photoelectrochemical cell. PMID:25455203

  5. Tailorable chiroptical activity of metallic nanospiral arrays.

    PubMed

    Deng, Junhong; Fu, Junxue; Ng, Jack; Huang, Zhifeng

    2016-02-18

    The engineering of the chiroptical activity of the emerging chiral metamaterial, metallic nanospirals, is in its infancy. We utilize glancing angle deposition (GLAD) to facilely sculpture the helical structure of silver nanospirals (AgNSs), so that the scope of chiroptical engineering factors is broadened to include the spiral growth of homochiral AgNSs, the combination of left- and right-handed helical chirality to create heterochiral AgNSs, and the coil-axis alignment of the heterochiral AgNSs. It leads to flexible control over the chiroptical activity of AgNS arrays with respect to the sign, resonance wavelength and amplitude of circular dichroism (CD) in the UV and visible regime. The UV chiroptical mode has a distinct response from the visible mode. Finite element simulation together with LC circuit theory illustrates that the UV irradiation is mainly adsorbed in the metal and the visible is preferentially scattered by the AgNSs, accounting for the wavelength-related chiroptical distinction. This work contributes to broadening the horizons in understanding and engineering chiroptical responses, primarily desired for developing a wide range of potential chiroplasmonic applications. PMID:26530309

  6. High-density Au nanorod optical field-emitter arrays

    NASA Astrophysics Data System (ADS)

    Hobbs, R. G.; Yang, Y.; Keathley, P. D.; Swanwick, M. E.; Velásquez-García, L. F.; Kärtner, F. X.; Graves, W. S.; Berggren, K. K.

    2014-11-01

    We demonstrate the design, fabrication, characterization, and operation of high-density arrays of Au nanorod electron emitters, fabricated by high-resolution electron beam lithography, and excited by ultrafast femtosecond near-infrared radiation. Electron emission characteristic of multiphoton absorption has been observed at low laser fluence, as indicated by the power-law scaling of emission current with applied optical power. The onset of space-charge-limited current and strong optical field emission has been investigated so as to determine the mechanism of electron emission at high incident laser fluence. Laser-induced structural damage has been observed at applied optical fields above 5 GV m-1, and energy spectra of emitted electrons have been measured using an electron time-of-flight spectrometer.

  7. High-density Au nanorod optical field-emitter arrays.

    PubMed

    Hobbs, R G; Yang, Y; Keathley, P D; Swanwick, M E; Velásquez-Garcíia, L F; Kärtner, F X; Graves, W S; Berggren, K K

    2014-11-21

    We demonstrate the design, fabrication, characterization, and operation of high-density arrays of Au nanorod electron emitters, fabricated by high-resolution electron beam lithography, and excited by ultrafast femtosecond near-infrared radiation. Electron emission characteristic of multiphoton absorption has been observed at low laser fluence, as indicated by the power-law scaling of emission current with applied optical power. The onset of space-charge-limited current and strong optical field emission has been investigated so as to determine the mechanism of electron emission at high incident laser fluence. Laser-induced structural damage has been observed at applied optical fields above 5 GV m(-1), and energy spectra of emitted electrons have been measured using an electron time-of-flight spectrometer. PMID:25354583

  8. Efficient Perovskite Solar Cells Depending on TiO2 Nanorod Arrays.

    PubMed

    Li, Xin; Dai, Si-Min; Zhu, Pei; Deng, Lin-Long; Xie, Su-Yuan; Cui, Qian; Chen, Hong; Wang, Ning; Lin, Hong

    2016-08-24

    Perovskite solar cells (PSCs) with TiO2 materials have attracted much attention due to their high photovoltaic performance. Aligned TiO2 nanorods have long been used for potential application in highly efficient perovskite solar cells, but the previously reported efficiencies of perovskite solar cells based on TiO2 nanorod arrays were underrated. Here we show a solvothermal method based on a modified ketone-HCl system with the addition of organic acids suitable for modulation of the TiO2 nanorod array films to fabricate highly efficient perovskite solar cells. Photovoltaic measurements indicated that efficient nanorod-structured perovskite solar cells can be achieved with the length of the nanorods as long as approximately 200 nm. A record efficiency of 18.22% under the reverse scan direction has been optimized by avoiding direct contact between the TiO2 nanorods and the hole transport materials, eliminating the organic residues on the nanorod surfaces using UV-ozone treatment and tuning the nanorod array morphologies through addition of different organic acids in the solvothermal process. PMID:27480286

  9. In-situ synthesis of photocatalytic CuAl2O4-Cu hybrid nanorod arrays.

    PubMed

    Ding, Dawei; Long, Mingce; Cai, Weimin; Wu, Yahui; Wu, Deyong; Chen, Chao

    2009-06-28

    Copper aluminate-copper hybrid nanorod arrays possessing superior visible-light driven photocatalytic properties were synthesized inside porous anodic aluminum oxide (AAO) under mild electrochemical conditions. PMID:19521617

  10. Effect of guided resonance modes on emission from GaN core-shell nanorod arrays

    NASA Astrophysics Data System (ADS)

    Anderson, P. Duke; Lin, Chenxi; Povinelli, Michelle L.

    2014-12-01

    We model the process of incoherent emission from quantum wells in GaN core-shell nanorod arrays using finite-difference time-domain simulations. We find that high-intensity features in the emitted field correspond to guided resonance modes near the -point of the photonic band structure. We identify one -point mode whose electric field intensity profile is ideal for core-shell nanorod array geometries. Using this mode, we are able to simultaneously enhance the radiative recombination rate and extraction efficiency relative to an in-filled slab. We determine the conditions on radiative and nonradiative recombination rates for which the nanorod array has a higher internal and external quantum efficiency than a reference slab. We present one nanorod array geometry where the external quantum efficiency is enhanced up to a factor of 25.

  11. Temperature dependence of the growth of ZnO nanorod arrays by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Kim, Hyunghoon; Moon, Jin Young; Lee, Ho Seong

    2011-03-01

    ZnO nanorod arrays were prepared by the electrochemical deposition route on conductive Au/Si substrates. The effect of the bath temperature on the growth of the ZnO nanorod arrays was investigated. With an increase in bath temperature from 30°C to 80°C, the deposited ZnO changed from an amorphous structure to a hexagonal crystal structure. The ZnO nanorod arrays grown above 50°C were dense and vertically well-aligned. Scanning and transmission electron microscopy results showed that the diameter of the hexagon-shaped ZnO nanorod arrays ranged from 100 nm to 180 nm and the length was about 500 nm. On the basis of the characteristics of the ZnO crystal structure and the effect of the bath temperature, the growth mechanism is described.

  12. Highly sensitive vertically standing Ag nanorod arrays substrates for surface enhanced fluorescence studies

    NASA Astrophysics Data System (ADS)

    Singh, Dhruv P.; Singh, J. P.

    2013-06-01

    The nanorods length dependence of surface enhanced fluorescence (SEF) has been investigated for Rhodamine 6G films adsorbed onto Ag nanorods array substrates grown by glancing angle deposition technique. It is found that the substrate enhancement efficiency increases with increase in the length (l) of nanorods from 450 nm to 1.7 μm. The silver nanorod arrays substrate with l =1.6 μm exhibited a remarkable enhancement factor (EF) of 72. However, the rate of increment in EF did not remain same. It varies faster for the values of l up to ˜1 μm and after that it increases at comparatively slower rate. The understanding of the effect of nanorods morphology on EF and the identification of high sensitivity SEF substrates is the novelty of this work. These SEF substrates can be used for sensing and trace detection of the fluorescent biological and chemical compounds.

  13. Multiplexed gold nanorod array biochip for multi-sample analysis.

    PubMed

    Wang, Yanyan; Tang, Liang

    2015-05-15

    Optical transduction of biological bindings based on localized surface plasmon resonance (LSPR) of gold nanorods (GNRs) is attractive for label-free biosensing. The aspect ratio (AR) dependence of LSPR band maxima inherently provides an ideal multiplex mechanism. GNRs of selected sizes can be combined to ensure distinct plasmon peaks in absorption spectrum. Monitoring the spectral shift at the dedicated peaks allows for simultaneous detection of the specific analyte. Here, we first transformed the GNR's multiplexed biosensing capability to a robust chip-based format. Specifically, nanorods of AR 2.6 and 4.5 were assembled onto thiol-terminated substrates, followed by functionalization of respective antibodies to construct a GNR multiplex biochip. As a model system, concentrations of human IgG and rabbit IgG were simultaneously measured by correlating red-shifts at distinct resonance peaks caused by specific target binding. The calibration curves exhibited linear relationship between the spectral shift and analyte amount. The sensing performance in multi-analyte mode correlated nicely with those for single analyte detection with minimal cross-reactivity. Moreover, mixed GNRs can be deposited in controllable array pattern on the glass chip to analyze numerous samples at the same time. Each GNRs dot functioned independently as a multiplexed plamonic sensor. Coupled with microplate reader, this GNR nanoarray chip can potentially result in large scale assay of samples concurrently while for each sample, a multi-analyte detection simultaneously if desired. The concept shown in this work is simple and versatile that will definitely be a new paradigm in high-throughput protein biochip development in the era of nano-biosensing. PMID:25127486

  14. Heterostructured TiO2 Nanorod@Nanobowl Arrays for Efficient Photoelectrochemical Water Splitting.

    PubMed

    Wang, Wenhui; Dong, Jingya; Ye, Xiaozhou; Li, Yang; Ma, Yurong; Qi, Limin

    2016-03-01

    Heterostructured TiO2 nanorod@nanobowl (NR@NB) arrays consisting of rutile TiO2 nanorods grown on the inner surface of arrayed anatase TiO2 nanobowls are designed and fabricated as a new type of photoanodes for photoelectrochemical (PEC) water splitting. The unique heterostructures with a hierarchical architecture are readily fabricated by interfacial nanosphere lithography followed by hydrothermal growth. Owing to the two-dimensionally arrayed structure of anatase nanobowls and the nearly radial alignment of rutile nanorods, the TiO2 NR@NB arrays provide multiple scattering centers and hence exhibit an enhanced light harvesting ability. Meanwhile, the large surface area of the NR@NB arrays enhances the contact with the electrolyte while the nanorods offer direct pathways for fast electron transfer. Moreover, the rutile/anatase phase junction in the NR@NB heterostructure improves charge separation because of the facilitated electron transfer. Accordingly, the PEC measurements of the TiO2 NR@NB arrays on the fluoride-doped tin oxide (FTO) substrate show significantly enhanced photocatalytic properties for water splitting. Under AM1.5G solar light irradiation, the unmodified TiO2 NR@NB array photoelectrode yields a photocurrent density of 1.24 mA cm(-2) at 1.23 V with respect to the reversible hydrogen electrode, which is almost two times higher than that of the TiO2 nanorods grown directly on the FTO substrate. PMID:26779803

  15. A Multiscale TiO2 Nanorod Array for Ultrasensitive Capture of Circulating Tumor Cells.

    PubMed

    Sun, Na; Li, Xinpan; Wang, Zhili; Zhang, Ruihua; Wang, Jine; Wang, Kewei; Pei, Renjun

    2016-05-25

    In this work, a uniform multiscale TiO2 nanorod array is fabricated to provide a "multi-scale interacting platform" for cell capture, which exhibits excellent capture specificity and sensitivity of the target cells after modification with bovine serum albumin (BSA) and DNA aptamer. After studying the capture performance of the BSA-aptamer TiO2 nanorod substrates and other nanostructured substrates, we can conclude that the multisacle TiO2 nanorod substrates could indeed effectively enhance the capture yields of target cancer cells. The capture yield of artificial blood samples on the BSA-aptamer TiO2 nanorod substrates is up to 85%-95%, revealing the potential application of the TiO2 nanorods on efficient and sensitive capture of rare circulating tumor cells. PMID:27176724

  16. Pt surface modification of SnO2 nanorod arrays for CO and H2 sensors.

    PubMed

    Huang, Hui; Ong, C Y; Guo, J; White, T; Tse, M S; Tan, O K

    2010-07-01

    Uniform SnO(2) nanorod arrays were deposited on a 4 inch SiO(2)/Si wafer by plasma-enhanced chemical vapor deposition (PEVCD) at low deposition temperature of around 300 degrees C. The SnO(2) nanorods were connected at the roots, thus the nanorod sensors could be fabricated by a feasible way compatible with microelectronic processes. The surface of the sensors was modified by Pt nanoparticles deposited by dip coating and sputtering, respectively. The sensing properties of the Pt-modified SnO(2) nanorod sensors to CO and H(2) gases were comparatively studied. After surface modification of Pt, the sensing response to CO and H(2) gases increased dramatically. The 2 nm Pt-modified SnO(2) nanorod sensors by sputtering showed the best sensing performance. By increasing Pt thickness from 2 nm up to 20 nm, the optimal working temperature decreased by 30 degrees C while the sensing response also decreased by about 4 times. Comparing these two Pt modification approaches by dip coating and sputtering, both could achieve comparable promotion effect if the Pt thickness can be controlled around its optimal value. The deposition technique of SnO(2) nanorod arrays by PECVD has good potential for scale-up and the fabrication process of nanorod sensors possesses simplicity and good compatibility with contemporary microelectronics-based technology. PMID:20648350

  17. Control over plasmon enhanced Raman and fluorescence from quasi free-standing Au nanorod arrays

    NASA Astrophysics Data System (ADS)

    Damm, Signe; Lordan, Frances; Murphy, Antony; McMillen, Mark; Pollard, Robert; Rice, James H.

    2014-08-01

    Nanoscale structures made from coinage metals such as gold or silver possess localized surface plasmon-polariton (LSP) excitations when the material interacts with light of the correct frequency and polarization. LSPs generated from freestanding 2D nanorod arrays have been applied to enable surface-enhanced Raman scattering (SERS) and surface enhanced fluorescence (SEF) spectra from Rhodamine 6G molecules adsorbed on the surface of the arrays. We study the conditions that optimize SERS and SEF from self-standing Au nanorod arrays by studying the effect of changing the surrounding environment using Al2O3 as a dielectric spacer layer.

  18. Evaporative Self-Assembly of Gold Nanorods into Macroscopic 3D Plasmonic Superlattice Arrays.

    PubMed

    Li, Penghui; Li, Yong; Zhou, Zhang-Kai; Tang, Siying; Yu, Xue-Feng; Xiao, Shu; Wu, Zhongzhen; Xiao, Quanlan; Zhao, Yuetao; Wang, Huaiyu; Chu, Paul K

    2016-04-01

    Millimeter-scale 3D superlattice arrays composed of dense, regular, and vertically aligned gold nanorods are fabricated by evaporative self-assembly. The regular organization of the gold nanorods into a macroscopic superlattice enables the production of a plasmonic substrate with excellent sensitivity and reproducibility, as well as reliability in surface-enhanced Raman scattering. The work bridges the gap between nanoscale materials and macroscopic applications. PMID:26823278

  19. Porous three-dimensional nanorod arrays through selective chemical etching of nanocomposites.

    PubMed

    He, Yuping; Brown, Cameron; He, Yizhuo; Fan, Jianguo; Lundgren, Cynthia A; Zhao, Yiping

    2012-08-11

    Three-dimensional Cu-Si and Cu-SiO(2) nanorod arrays containing ~68 at% Cu have been fabricated by a glancing angle co-deposition technique. By selectively etching Cu in 0.05 M KCN methanol solution, porous nanorods with different shapes form, which are promising for applications in sensors, catalysts, and as medical capsules that are able to be loaded with functional materials. PMID:22777132

  20. Effect of growth time on ZnO nanorod arrays by a facile sonicated sol-gel immersion technique

    NASA Astrophysics Data System (ADS)

    Malek, M. F.; Mamat, M. H.; Musa, M. Z.; Ishak, A.; Saurdi, I.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2016-07-01

    A facile sonicated sol-gel immersion technique has been presented for synthesizing ZnO nanorod arrays with controllable diameter and lengths on glass substrates. A sol-gel dip-coating deposition was first used to grow a thin layer of ZAO nanocrystals on substrate serving as seeds for the subsequent growth of the nanorod arrays. The effect of growth time of the ZnO nanorod arrays on the ZAO seed layer were investigated. The optical transmission properties of the ZnO nanorods has been investigated. The thickness of the nanorods can be controlled by the growth time. These highly oriented ZnO nanorod arrays are potential for the creation of functional materials, such as the electrode of the solar cells, optoelectronic devices and etc.

  1. Ultrafast switching of tunable infrared plasmons in indium tin oxide nanorod arrays with large absolute amplitude

    NASA Astrophysics Data System (ADS)

    Guo, Peijun; Schaller, Richard D.; Ketterson, John B.; Chang, Robert P. H.

    2016-04-01

    All-optical control of plasmons can enable optical switches with high speeds, small footprints and high on/off ratios. Here we demonstrate ultrafast plasmon modulation in the near-infrared (NIR) to mid-infrared (MIR) range by intraband pumping of indium tin oxide nanorod arrays (ITO-NRAs). We observe redshifts of localized surface plasmon resonances arising from a change of the plasma frequency of ITO, which is governed by the conduction band non-parabolicity. We generalize the plasma frequency for non-parabolic bands, quantitatively model the fluence-dependent plasma frequency shifts, and show that different from noble metals, the lower electron density in ITO enables a remarkable change of electron distributions, yielding a significant plasma frequency modulation and concomitant large transient bleaches and induced absorptions, which can be tuned spectrally by tailoring the ITO-NRA geometry. The low electron heat capacity explains the sub-picosecond kinetics that is much faster than noble metals. Our work demonstrates a new scheme to control infrared plasmons for optical switching, telecommunications and sensing.

  2. Digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing

    NASA Astrophysics Data System (ADS)

    Jiang, Wei; He, Xiaoning; Liu, Hongzhong; Yin, Lei; Shi, Yongsheng; Ding, Yucheng

    2014-11-01

    In this article, we report on the digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing. The pattern of TiO2 nanorod arrays can be easily designed and fabricated by laser scanning technology integrated with a computer-aided design system, which allows a high degree of freedom corresponding to the various pattern design demands. The approach basically involves the hydrothermal growth of TiO2 nanorod arrays on a transparent conductive substrate, the micropattern of TiO2 nanorod arrays and surface fluorination treatment. With these micro/nano-composite TiO2 nanorod array based films, we have demonstrated superhydrophilic patterned TiO2 nanorod arrays with rapid water spreading ability and superhydrophobic patterned TiO2 nanorod arrays with an excellent droplet bouncing effect and a good self-cleaning performance. The dynamic behaviours of the water droplets observed on the patterned TiO2 nanorod arrays were demonstrated by experiments and simulated by a finite element method. The approaches we will show are expected to provide potential applications in fields such as self-cleaning, surface protection, anticrawling and microfluidic manipulation.

  3. Crystallographic, luminescence and photoconductive characteristics of chemically tailored ZnO nanorods

    SciTech Connect

    Bayan, Sayan Chakraborty, Purushottam

    2014-04-24

    The optoelectronic properties of zinc oxide (ZnO) nanorods synthesized using two different chemical methods have been explored in the light of microstructural features. The presence/absence of band edge emission in the luminescence spectra of the nanorods is found to be governed by the crystallographic properties. Moreover, we observed a pronounced effect of variation in crystallite size on the UV photoconductivity of the nanorods. Understanding the influence of microstructural aspects on the optical and electronic properties of the nanostructures may help in the fabrication of prototype, miniaturized optoelectronic devices.

  4. Growth of Si nanorods in honeycomb and hexagonal-closed-packed arrays using glancing angle deposition

    SciTech Connect

    Patzig, Christian; Rauschenbach, Bernd; Fuhrmann, Bodo; Leipner, Hartmut S.

    2008-01-15

    Regular arrays of Si nanorods with a circular cross section in hexagonal-closed-packed and triangular cross section in honeycomblike arrangements were grown using glancing angle deposition on Si(100) and fused silica substrates that were patterned with Au dots using self-assembled mono- and double layers of polystyrene nanospheres as an evaporation mask. The Au dots were used as an etching mask for the underlying silica substrates in a reactive ion beam etching process, which greatly enhanced the height of the seeding spaces for the subsequent glancing angle deposition. An elongated shadowing length l of the prepatterned nucleation sites and less growth of Si structures between the surface mounds could be achieved this way. Differences in form, height, and diameter of the Si nanorods grown on either hcp or honeycomb arrays are explained by purely geometrical arguments. Different seed heights and interseed distances are found to be the main reasons for the strong distinctions between the grown nanorod arrays.

  5. Template-free synthesis of Ta3N5 nanorod arrays for efficient photoelectrochemical water splitting.

    PubMed

    Zhen, Chao; Wang, Lianzhou; Liu, Gang; Lu, Gao Qing Max; Cheng, Hui-Ming

    2013-04-14

    We report the template-free synthesis of Ta3N5 nanorod array films grown on Ta foil by a combination of a vapor-phase hydrothermal process and subsequent nitriding. The Ta3N5 nanorod array film modified with Co(OH)x when used as a photoanode in a photoelectrochemical cell for water splitting yields a stable photocurrent density of 2.8 mA cm(-2) at 1.23 VRHE under AM 1.5G simulated sunlight. The incident photon-to-current conversion efficiency at 480 nm is determined to be 37.8%. PMID:23463440

  6. Effect of matrix on Raman scattering and luminescence in 2D gold nanorod arrays

    NASA Astrophysics Data System (ADS)

    Damm, Signe; Lordan, Frances; Murphy, Antony; McMillen, Mark; Pollard, Robert; Rice, James H.

    2014-05-01

    In this paper we probe the surface enhanced fluorescence (SEF) and Raman scattering (SERS) from arrays of selfstanding Au nanorod arrays embedded within a porous alumina template (AAO). By controlling the thickness of the AAO matrix both SEF and SERS are observed exhibiting an inverse relationship. SERS and SEF show a nonlinear response to the removal of AAO matrix due to an inhomogeneous plasmon activity across the nanorod. Optimization of the level of alumina matrix thickness optimizes conditions for obtaining either maximized SERS, SEF or for simultaneously observing both SERS and SEF together.

  7. Shape controllable synthesis of ZnO nanorod arrays via vapor phase growth

    NASA Astrophysics Data System (ADS)

    Sun, Xiaochen; Zhang, Hongzhou; Xu, Jun; Zhao, Qing; Wang, Rongming; Yu, Dapeng

    2004-03-01

    ZnO nanorod arrays with peculiar morphologies were synthesized on (111)-oriented Si substrate and glass via a vapor phase growth. The morphology of the individual nanorod can be flat-headed bottle-like, and needle-like, which depends on the deposition positions relative to the source materials in the presence of a controlling element Se. In addition, the arrays of all the three morphologies exhibit good alignment and high coverage. This fabrication technique can be also used to direct the controllable growth of other nanomaterials with similar morphologies.

  8. Synthesis and electrochromic property of single-crystalline V2O5 nanorod arrays by template-based deposition

    NASA Astrophysics Data System (ADS)

    Takahashi, Katsunori; Limmer, Steven J.; Wang, Ying; Cao, Guozhong

    2004-10-01

    Growth and electrochemical and optical properties of single crystalline vanadium pentoxide (V2O5) nanorod arrays were investigated. Vanadium pentoxide nanorod arrays were grown by electrochemical deposition, surface condensation induced by a pH change and sol electrophoretic deposition. Uniformly sized vanadium oxide nanorods with a length of about 10μm and diameters of 100 or 200nm were grown over a large area with near unidirectional alignment. TEM micrographs and electron diffraction patterns of V2O5 nanorods clearly show the single-crystalline nature of nanorods from all three growth routes with a growth direction of [010]. The growth mechanisms of single crystal vanadium pentoxide nanorods have been discussed. The transmittance of nanorod arrays decrease more quickly under applied electric field than sol-gel derived film, which suggests nanorod array electrodes possess significantly improved charge/discharge rate. Electrochemical analysis is proves that nanorod arrays have higher efficiency than sol-gel derived film. The relationships between electrochemical and optical properties, nano and microstructures, and growth mechanisms have been discussed.

  9. Site-specific multi-stage CVD of large-scale arrays of ultrafine ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Zhang, X. X.; Zhao, D.; Gao, M.; Dong, H. B.; Zhou, W. Y.; Xie, S. S.

    2011-04-01

    Multi-stage growth of ZnO nanorod arrays has been carried out by Au-assisted chemical vapor deposition (CVD) in order to better understand and more precisely control the growth behaviors. It is evidenced that Au-catalyzed vapor-liquid-solid (VLS) growth only dominates the initial site-specific nucleation of the nanorods, while the subsequent growth is governed by a vapor-solid (VS) epitaxy mechanism. The sequential VLS and VS behaviors permit the fabrication of large-scale highly ordered arrays of ZnO nanorods with precisely tunable diameters and embedded junctions by controlling reactant concentration and nanorod top morphology. Based on the above results, two routes to fabricate ultrafine ZnO nanorod arrays are proposed and stepwise nanorod arrays with ultrafine top segment (~10 nm in diameter) have been achieved. Temperature-dependent photoluminescence (PL) and spatial resolved PL were carried out on the nanorod arrays and on individual nanorods, indicating high quality optical properties and tunable light emission along the length of the stepwise nanorods.

  10. Core-Shell CdS-Cu₂S Nanorod Array Solar Cells.

    PubMed

    Wong, Andrew Barnabas; Brittman, Sarah; Yu, Yi; Dasgupta, Neil P; Yang, Peidong

    2015-06-10

    As an earth-abundant p-type semiconductor, copper sulfide (Cu2S) is an attractive material for application in photovoltaic devices. However, it suffers from a minority carrier diffusion length that is less than the length required for complete light absorption. Core-shell nanowires and nanorods have the potential to alleviate this difficulty because they decouple the length scales of light absorption and charge collection. To achieve this geometry using Cu2S, cation exchange was applied to an array of CdS nanorods to produce well-defined CdS-Cu2S core-shell nanorods. Previous work has demonstrated single-nanowire photovoltaic devices from this material system, but in this work, the cation exchange chemistry has been applied to nanorod arrays to produce ensemble-level devices with microscale sizes. The core-shell nanorod array devices show power conversion efficiencies of up to 3.8%. In addition, these devices are stable when measured in air after nearly one month of storage in a desiccator. These results are a first step in the development of large-area nanostructured Cu2S-based photovoltaics that can be processed from solution. PMID:25993088

  11. Describing the dispersion of plasmonic nanorod arrays via coupling of elementary excitations

    NASA Astrophysics Data System (ADS)

    Vaianella, Fabio; Maes, Bjorn

    2016-04-01

    Metamaterials such as metal-dielectric multilayers and cylindrical nanowires are well known, for instance because of their hyperbolic dispersion. Here we examine in detail the mode characteristics in an array of square and rectangular metallic nanorods. In particular we propose a method to describe the dispersion via the coupling of specific elementary excitations. Apparently, these fundamental modes depend on the size and shape of the nanorods, and on the particular symmetry of the Bloch modes. Specifically, we show that arrays of relatively small square nanorods are associated with coupling of single rod modes. In contrast, large nanorod arrays correspond with a basic structure consisting of four metallic corners. In the medium size case, the nature of the elementary excitation depends on the frequency range and Bloch mode symmetry. Finally, we study rectangular nanorods, which turn out to derive from a basic geometry with two semi-infinite rods. The analysis method is thus useful for a better comprehension of many other types of metamaterials.

  12. The effects of nanocavity and photonic crystal in InGaN/GaN nanorod LED arrays.

    PubMed

    Jiao, Qianqian; Chen, Zhizhong; Feng, Yulong; Li, Shunfeng; Jiang, Shengxiang; Li, Junze; Chen, Yifan; Yu, Tongjun; Kang, Xiangning; Shen, Bo; Zhang, Guoyi

    2016-12-01

    InGaN/GaN nanorod light-emitting diode (LED) arrays were fabricated using nanoimprint and reactive ion etching. The diameters of the nanorods range from 120 to 300 nm. The integral photoluminescence (PL) intensity for 120 nm nanorod LED array is enhanced as 13 times compared to that of the planar one. In angular-resolved PL (ARPL) measurements, there are some strong lobes as resonant regime appeared in the far-field radiation patterns of small size nanorod array, in which the PL spectra are sharp and intense. The PL lifetime for resonant regime is 0.088 ns, which is 40 % lower than that of non-resonant regime for 120 nm nanorod LED array. At last, three dimension finite difference time domain (FDTD) simulation is performed. The effects of guided modes coupling in nanocavity and extraction by photonic crystals are explored. PMID:27440081

  13. The effects of nanocavity and photonic crystal in InGaN/GaN nanorod LED arrays

    NASA Astrophysics Data System (ADS)

    Jiao, Qianqian; Chen, Zhizhong; Feng, Yulong; Li, Shunfeng; Jiang, Shengxiang; Li, Junze; Chen, Yifan; Yu, Tongjun; Kang, Xiangning; Shen, Bo; Zhang, Guoyi

    2016-07-01

    InGaN/GaN nanorod light-emitting diode (LED) arrays were fabricated using nanoimprint and reactive ion etching. The diameters of the nanorods range from 120 to 300 nm. The integral photoluminescence (PL) intensity for 120 nm nanorod LED array is enhanced as 13 times compared to that of the planar one. In angular-resolved PL (ARPL) measurements, there are some strong lobes as resonant regime appeared in the far-field radiation patterns of small size nanorod array, in which the PL spectra are sharp and intense. The PL lifetime for resonant regime is 0.088 ns, which is 40 % lower than that of non-resonant regime for 120 nm nanorod LED array. At last, three dimension finite difference time domain (FDTD) simulation is performed. The effects of guided modes coupling in nanocavity and extraction by photonic crystals are explored.

  14. Characteristics of zinc oxide nanorod array/titanium oxide film heterojunction prepared by aqueous solution deposition

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Hong, Min-Hsuan; Li, Bo-Wei

    2016-07-01

    The characteristics of a ZnO nanorod array/TiO2 film heterojunction were investigated. A TiO2 film was prepared on glass by aqueous solution deposition with precursors of ammonium hexafluorotitanate and boric acid at 40 °C. Then, a ZnO seed layer was prepared on a TiO2 film/glass substrate by RF sputtering. A vertically oriented ZnO nanorod array was grown on a ZnO seed layer/TiO2 film/glass substrate by aqueous solution deposition with precursors of zinc nitrate and hexamethylenetetramine (HMT) at 70 °C. After thermal annealing in N2O ambient at 300 °C, this heterojunction used as an oxygen gas sensor shows much better rise time, decay time, and on/off current ratio than as-grown and annealed ZnO nanorods.

  15. Arrays of nanorods composed of ZnO nanodots exhibiting enhanced UV emission and stability

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Sun, Y.; Yu, M.; Liu, X.; Yang, B.; Liu, D.; Liu, S.; Cao, W.; Ashfold, Michael N. R.

    2014-08-01

    A novel one-step coating and assembly approach for fabricating well-defined ZnO nanodot/SiO2 nanorod arrays by hydrolysis-recrystallization growth from 1-D ZnO nanorods is described. The resultant composite nanorod arrays exhibit much enhanced UV emission efficiencies and excellent stability, and thus offer particular promise for application in UV emission devices operating in harsh environments.A novel one-step coating and assembly approach for fabricating well-defined ZnO nanodot/SiO2 nanorod arrays by hydrolysis-recrystallization growth from 1-D ZnO nanorods is described. The resultant composite nanorod arrays exhibit much enhanced UV emission efficiencies and excellent stability, and thus offer particular promise for application in UV emission devices operating in harsh environments. Electronic supplementary information (ESI) available: Suggested reaction scheme for the chemical processes occurring in this work; TEM images of ZnO NRs treated with 50 μL of TEOS; the diameter distribution of the ZnO NDs inside the ZnO/SiO2 NRs; PL spectra of as-grown ZnO NRs and of NRs after O2 and Ar plasma treatment; PL spectra of as-grown ZnO NRs and of NRs after annealing in O2 and in Ar; plot showing the time dependence of the relative UV emission intensity of the as-grown ZnO NRs and the TEOS-treated ZnO NRs immersed in an aqueous buffer solution at pH = 9.18; PL spectra of as-grown ZnO NRs and of the silica powders formed by hydrolysis and condensation reactions of TEOS; PL spectra of SiO2 powder after annealing in O2 at 300, 600 and 900 °C. See DOI: 10.1039/c4nr01558d

  16. A facile method for the synthesis of tapered ZnO:Cu nanorod arrays and its secondary growth

    NASA Astrophysics Data System (ADS)

    Huang, Jun; Hu, Liang; Zhang, Honghai; Zhang, Jie; Yang, Xiaopeng; Li, Dehui; Zhu, Liping; Ye, Zhizhen

    2012-07-01

    A facile thermal diffusion method has been employed to synthesize tapered ZnO:Cu nanorod arrays. The plain hexagonal ZnO nanorods gradually turned into round cylinder and then tapered nanorods during thermal treatment. The shape evolution was explained by the terrace-ledge-kink model. Moreover, a small amount of copper has been incorporated into the nanorods during high temperature thermal treatment. Both X-ray photoelectron spectrum and photoluminescence results indicated that a number of oxygen vacancies exist in copper diffused samples. In addition, a catalyst free secondary growth was achieved on the tapered ZnO:Cu nanorod arrays. High resolution transmission electron microscope result showed that the tapered nanorods after secondary growth remained as a single crystal and the thinner section was epitaxially grown on the tip.

  17. Hydrogen peroxide generation and photocatalytic degradation of estrone by microstructural controlled ZnO nanorod arrays

    NASA Astrophysics Data System (ADS)

    Liu, Yangsi; Han, Jie; Qiu, Wei; Gao, Wei

    2012-12-01

    The strong oxidant, hydrogen peroxide (H2O2), generated by ZnO nanorod arrays under UV light irradiation was monitored by fluorescence analysis. The ZnO nanorod arrays were synthesized via a low temperature hydrothermal method and their dimensions, i.e., diameter and height, can be controlled by adjusting the concentration of zinc nitrate (Zn(NO3)2·6H2O) and hexamethylenetetramine (HMT). The morphology, nanostructure, surface roughness and optical property were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmittance spectra, respectively. The ZnO nanorod arrays were applied in the degradation of estrone, which is an emerging steroid estrogen contaminant. The results revealed that the ZnO nanorod array produced from 25 mM Zn2+ and HMT had the highest aspect ratio, the largest surface roughness and the lowest band gap energy, which was beneficial to the efficiency of UV light utilization, photocatalytic degradation of estrone and H2O2 generation.

  18. The use of silver nanorod array based surface enhanced Raman scattering sensor for food safety applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For the advancement of preventive strategies, it is critical to develop rapid and sensitive detection methods with nanotechnology for food safety applications. This article reports the recent development on the use of aligned silver nanorod (AgNR) arrays prepared by oblique angle deposition, as surf...

  19. Facile synthesis of ZnO/CuInS2 nanorod arrays for photocatalytic pollutants degradation.

    PubMed

    Yang, Yawei; Que, Wenxiu; Zhang, Xinyu; Xing, Yonglei; Yin, Xingtian; Du, Yaping

    2016-11-01

    Vertically-aligned ZnO nanorod arrays on a fluorine-doped tin oxide glass substrate were homogeneously coated with visible light active CuInS2 quantum dots by using a controllable electrophoretic deposition strategy. Compared with the pure ZnO nanorod arrays, the formation of high-quality ZnO/CuInS2 heterojunction with well-matched band energy alignment expanded the light absorption from ultraviolet to visible region and facilitated efficient charge separation and transportation, thus yielding remarkable enhanced photoelectrochemical performance and photocatalytic activities for methyl orange and 4-chlorophenol degradation. The ZnO/CuInS2 film with the deposition duration of 80min showed the highest degradation rate and photocurrent density (0.95mA/cm(2)), which was almost 6.33 times higher than that of the pure ZnO nanorod arrays film. The CuInS2 QDs sensitized ZnO nanorod arrays film was proved to be a superior structure for photoelectrochemical and photocatalytic applications due to the optimized CuInS2 loading and well-maintained one-dimensional nanostructure. PMID:27322900

  20. Uniform SiGe/Si quantum well nanorod and nanodot arrays fabricated using nanosphere lithography

    PubMed Central

    2013-01-01

    This study fabricates the optically active uniform SiGe/Si multiple quantum well (MQW) nanorod and nanodot arrays from the Si0.4Ge0.6/Si MQWs using nanosphere lithography (NSL) combined with the reactive ion etching (RIE) process. Compared to the as-grown sample, we observe an obvious blueshift in photoluminescence (PL) spectra for the SiGe/Si MQW nanorod and nanodot arrays, which can be attributed to the transition of PL emission from the upper multiple quantum dot-like SiGe layers to the lower MQWs. A possible mechanism associated with carrier localization is also proposed for the PL enhancement. In addition, the SiGe/Si MQW nanorod arrays are shown to exhibit excellent antireflective characteristics over a wide wavelength range. These results indicate that SiGe/Si MQW nanorod arrays fabricated using NSL combined with RIE would be potentially useful as an optoelectronic material operating in the telecommunication range. PMID:23924368

  1. Tailoring the surface of ZnO nanorods into corrugated nanorods via a selective chemical etch method

    NASA Astrophysics Data System (ADS)

    Duan, Xiangyang; Chen, Guangde; Li, Chu; Yin, Yuan; Jin, Wentao; Guo, Lu’an; Ye, Honggang; Zhu, Youzhang; Wu, Yelong

    2016-07-01

    Using the chemical vapour deposition method, we successfully converted smooth ZnO nanorods (NRs) into corrugated NRs by simply increasing the reaction time. The surface morphology and crystallographic structure of the corrugated NRs were investigated. The corrugated NRs were decorated by alternant (11\\bar{2}1) and (11\\bar{2}\\bar{1}) planes at the exposed side surfaces while the conventional \\{10\\bar{1}0\\} planes disappeared. No twinning boundaries were found in the periodically corrugated structures, indicating that they were type II corrugated NRs. Further investigation told us that they were selectively etched. We introduced a hydrothermal method to synthesize the smooth ZnO NRs and then etched them in a tube furnace at 950 °C with a flow of carbon monoxide. By separating the growth stage and the selective etching stage, we explicitly demonstrated a successfully selective etching effect on ZnO NRs with a carbon monoxide reducing atmosphere for the first time. An etching mechanism based on the selective reaction between carbon monoxide and the different exposed surfaces was proposed. Our results will improve the understanding of the growth mechanism on coarse or corrugated NRs and provide a new strategy for the application of surface controlled nanostructured materials.

  2. Tailoring the surface of ZnO nanorods into corrugated nanorods via a selective chemical etch method.

    PubMed

    Duan, Xiangyang; Chen, Guangde; Li, Chu; Yin, Yuan; Jin, Wentao; Guo, Lu'an; Ye, Honggang; Zhu, Youzhang; Wu, Yelong

    2016-07-22

    Using the chemical vapour deposition method, we successfully converted smooth ZnO nanorods (NRs) into corrugated NRs by simply increasing the reaction time. The surface morphology and crystallographic structure of the corrugated NRs were investigated. The corrugated NRs were decorated by alternant [Formula: see text] and [Formula: see text] planes at the exposed side surfaces while the conventional [Formula: see text] planes disappeared. No twinning boundaries were found in the periodically corrugated structures, indicating that they were type II corrugated NRs. Further investigation told us that they were selectively etched. We introduced a hydrothermal method to synthesize the smooth ZnO NRs and then etched them in a tube furnace at 950 °C with a flow of carbon monoxide. By separating the growth stage and the selective etching stage, we explicitly demonstrated a successfully selective etching effect on ZnO NRs with a carbon monoxide reducing atmosphere for the first time. An etching mechanism based on the selective reaction between carbon monoxide and the different exposed surfaces was proposed. Our results will improve the understanding of the growth mechanism on coarse or corrugated NRs and provide a new strategy for the application of surface controlled nanostructured materials. PMID:27276661

  3. Silver-Nanorod Bundles: A Hierarchically Ordered Array of Silver-Nanorod Bundles for Surface-Enhanced Raman Scattering Detection of Phenolic Pollutants (Adv. Mater. 24/2016).

    PubMed

    Zhu, Chuhong; Meng, Guowen; Zheng, Peng; Huang, Qing; Li, Zhongbo; Hu, Xiaoye; Wang, Xiujuan; Huang, Zhulin; Li, Fadi; Wu, Nianqiang

    2016-06-01

    G. Meng, N. Wu, and co-workers develop a hierarchically ordered array of silver nanorod bundles for surface-enhanced Raman scattering (SERS) detection. As described on page 4871, in each bundle, small gaps are formed between adjacent silver nanorods upon solution evaporation. At these sites, "hot spots" are generated where analyte molecules are trapped, leading to high sensitivity of the SERS sensor. PMID:27311094

  4. Hydroxyapatite coatings with oriented nanoplate and nanorod arrays: Fabrication, morphology, cytocompatibility and osteogenic differentiation.

    PubMed

    Chen, Wei; Tian, Bo; Lei, Yong; Ke, Qin-Fei; Zhu, Zhen-An; Guo, Ya-Ping

    2016-10-01

    Hydroxyapatite (HA) crystals exhibit rod-like shape with c-axis orientation and plate-like shape with a(b)-axis orientation in vertebrate bones and tooth enamel surfaces, respectively. Herein, we report the synthesis of HA coatings with the oriented nanorod arrays (RHACs) and HA coatings with oriented nanoplate arrays (PHACs) by using bioglass coatings as sacrificial templates. After soaking in simulated body fluid (SBF) at 120°C, the bioglass coatings are hydrothermally converted into the HA coatings via a dissolution-precipitation reaction. If the Ca/P ratios in SBF are 2.50 and 1.25, the HA crystals on the coatings are oriented nanorod arrays and oriented nanoplate arrays, respectively. Moreover, the bioglass coatings are treated with SBF at 37°C, plate-like HA coatings with a low crystallinity (SHACs) are prepared. As compared with the Ti6Al4V and SHACs, the human bone marrow stromal cells (hBMSCs) on the RHACs and PHACs have better cell adhesion, spreading, proliferation and osteogenic differentiation because of their moderately hydrophilic surfaces and similar chemical composition, morphology and crystal orientation to human hard tissues. Notably, the morphologies of HA crystals have no obvious effects on cytocompatibility and osteogenic differentiation. Hence, the HA coatings with oriented nanoplate arrays or oriented nanorod arrays have a great potential for orthopedic applications. PMID:27287136

  5. Low-temperature growth of well-aligned zinc oxide nanorod arrays on silicon substrate and their photocatalytic application

    PubMed Central

    Azam, Ameer; Babkair, Saeed Salem

    2014-01-01

    Well-aligned and single-crystalline zinc oxide (ZnO) nanorod arrays were grown on silicon (Si) substrate using a wet chemical route for the photodegradation of organic dyes. Structural analysis using X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction confirmed the formation of ZnO nanorods grown preferentially oriented in the (001) direction and with a single phase nature with a wurtzite structure. Field emission scanning electron microscopy and transmission electron microscopy micrographs showed that the length and diameter of the well-aligned rods were about ~350–400 nm and ~80–90 nm, respectively. Raman scattering spectra of ZnO nanorod arrays revealed the characteristic E2 (high) mode that is related to the vibration of oxygen atoms in the wurtzite ZnO. The photodegradation of methylene blue (MB) using ZnO nanorod arrays was performed under ultraviolet light irradiation. The results of photodegradation showed that ZnO nanorod arrays were capable of degrading ~80% of MB within 60 minutes of irradiation, whereas ~92% of degradation was achieved in 120 minutes. Complete degradation of MB was observed after 270 minutes of irradiation time. Owing to enhanced photocatalytic degradation efficiency and low-temperature growth method, prepared ZnO nanorod arrays may open up the possibility for the successful utilization of ZnO nanorod arrays as a future photocatalyst for environmental remediation. PMID:24812511

  6. Ultra-violet Sensing Characteristic and Field Emission Properties of Vertically Aligned Aluminum Doped Zinc Oxide Nanorod Arrays

    SciTech Connect

    Mamat, M. H.; Malek, M. F.; Musa, M. Z.; Khusaimi, Z.; Rusop, M.

    2011-05-25

    Ultra-violet (UV) sensing behavior and field emission characteristic have been investigated on vertically aligned aluminum (Al) doped zinc oxide (ZnO) nanorod arrays prepared using sol-gel immersion method. Uniform and high coverage density of ZnO nanorod arrays have been successfully deposited on seeded-catalyst coated substrates. The synthesized nanorods have diameter sizes between 50 nm to 150 nm. The XRD spectra show Al doped ZnO nanorod array has high crystallinity properties with the dominancy of crystal growth along (002) plane or c-axis. UV photoresponse measurement indicates that Al doped ZnO nanorod array sensitively detects UV light as shown by conductance increment after UV illumination exposure. The nanorod array shows good field emission properties with low turn on field and threshold field at 2.1 V/{mu}m and 5.6 V/{mu}m, respectively. The result suggested that Al doped ZnO nanorod arrays prepared by low-cost sol-gel immersion method show promising result towards fabrication of multi applications especially in UV photoconductive sensor and field emission displays.

  7. High intensity, plasma-induced emission from large area ZnO nanorod array cathodes

    SciTech Connect

    Liao Qingliang; Yang Ya; Qi Junjie; Zhang Yue; Huang Yunhua; Qin Zi; Xia Liansheng

    2008-11-15

    High intensity electron emission cathodes based on a well-aligned ZnO nanorod array were fabricated. An investigation of the properties of the plasma and the electron beams produced by ZnO nanorod array cathodes was presented. Intense current electron beams were obtained from the cathodes. At an electric field of 7-8 V/{mu}m and pulse duration of {approx}100 ns, the highest emission current density reached 76-91 A/cm{sup 2}. The production mechanism of the electron beams was the plasma-induced emission. The morphology and structure of the ZnO nanorod after the application of the accelerating pulses were characterized. The plasma expanded at a velocity of about 10.7 cm/{mu}s during the pulse interval. Whether the emission currents are high or low, the plasma on the cathode surface were always distributed uniformly. The ZnO nanorod array cathodes are expected to be applied to high power vacuum electronic devices as electron beam sources.

  8. Abnormal Cathodic Photocurrent Generated on an n-Type FeOOH Nanorod-Array Photoelectrode.

    PubMed

    Chen, Hongjun; Lyu, Miaoqiang; Liu, Gang; Wang, Lianzhou

    2016-03-24

    A simple, wet-chemical method for the synthesis of an FeOOH nanorod-array photoelectrode on fluorine-doped tin oxide (FTO) glass is reported. Nanorods of diameter about 35 nm and length about 300 nm have been vertically grown on an FTO substrate. Upon calcination, the FeOOH phase could be easily converted to a hematite structure while maintaining the shape of the nanorod array. An interesting abnormal cathodic photocurrent is generated on the FeOOH nanorod-array photoelectrode under illumination, which is totally different from that obtained on a calcined hematite photoelectrode under the same experimental conditions. The cathodic photocurrent density generated on the FeOOH photoelectrode can also be tuned by applying an electrochemical anodic or cathodic treatment. Detailed analysis has revealed that higher valence state Fe(IV) species in the FeOOH photoelectrode play an important role in sacrificing the photoexcited electrons for generation of the cathodic photocurrent. Comparison between the FeOOH and hematite photoelectrodes allows for a better understanding of the interplay between crystal structure, surface reactions, and photocurrent. The findings on this new abnormal phenomenon could also provide guidance for the design of new types of semiconducting photoelectrochemical devices. PMID:26879339

  9. Synthesis and photoluminescence of quasi-arrayed ZnMgO nanorods

    NASA Astrophysics Data System (ADS)

    Wang, Fazhan; Zhao, Chao; Liu, Bo; Yuan, Sicong

    2009-06-01

    Quasi-arrayed ZnMgO single-crystal nanorods with different Mg concentrations have been fabricated by thermal evaporation of Zn and Mg on a Si substrate using Au as a catalyst. The synthesized ZnMgO nanorods had uniform flat hexagonal crystallorgraphic planes with diameters of about 300 nm. It was found that with the increase in the dopant concentration, the peak position of (0 0 2) was shifted towards the high-angle side (from 34.40° to 34. 54°) and the near-band-edge emission was blue-shifted to 364 nm (3.41 eV) from 385 nm (3.22 eV) in comparison with that of pure ZnO. The direct modulation of the band-gap caused by Mg substitution was responsible for the blue shift. The possible growth mechanism of the ZnMgO nanorods was discussed.

  10. Zinc Oxide Nanorods Shielded with an Ultrathin Nickel Layer: Tailoring of Physical Properties.

    PubMed

    Mudusu, Devika; Nandanapalli, Koteeswara Reddy; Dugasani, Sreekantha Reddy; Park, Sung Ha; Tu, Charles W

    2016-01-01

    We report on the development of Ni-shielded ZnO nanorod (NR) structures and the impact of the Ni layer on the ZnO NR properties. We developed nickel-capped zinc oxide nanorod (ZnO/Ni NR) structures by e-beam evaporation of Ni and the subsequent annealing of the ZnO/Ni core/shell nanostructures. The core/shell NRs annealed at 400 °C showed superior crystalline and emission properties. More interestingly, with the increase of annealing temperature, the crystallinity of the Ni shells over the ZnO NRs gradually changed from polycrystalline to single crystalline. The presence of the Ni layer as a polycrystalline shell completely hindered the light emission and transmission of the ZnO NR cores. Further, the band gap of ZnO NRs continuously decreased with the increase of annealing temperature. PMID:27334555

  11. Zinc Oxide Nanorods Shielded with an Ultrathin Nickel Layer: Tailoring of Physical Properties

    PubMed Central

    Mudusu, Devika; Nandanapalli, Koteeswara Reddy; Dugasani, Sreekantha Reddy; Park, Sung Ha; Tu, Charles W.

    2016-01-01

    We report on the development of Ni-shielded ZnO nanorod (NR) structures and the impact of the Ni layer on the ZnO NR properties. We developed nickel-capped zinc oxide nanorod (ZnO/Ni NR) structures by e-beam evaporation of Ni and the subsequent annealing of the ZnO/Ni core/shell nanostructures. The core/shell NRs annealed at 400 °C showed superior crystalline and emission properties. More interestingly, with the increase of annealing temperature, the crystallinity of the Ni shells over the ZnO NRs gradually changed from polycrystalline to single crystalline. The presence of the Ni layer as a polycrystalline shell completely hindered the light emission and transmission of the ZnO NR cores. Further, the band gap of ZnO NRs continuously decreased with the increase of annealing temperature. PMID:27334555

  12. Zinc Oxide Nanorods Shielded with an Ultrathin Nickel Layer: Tailoring of Physical Properties

    NASA Astrophysics Data System (ADS)

    Mudusu, Devika; Nandanapalli, Koteeswara Reddy; Dugasani, Sreekantha Reddy; Park, Sung Ha; Tu, Charles W.

    2016-06-01

    We report on the development of Ni-shielded ZnO nanorod (NR) structures and the impact of the Ni layer on the ZnO NR properties. We developed nickel-capped zinc oxide nanorod (ZnO/Ni NR) structures by e-beam evaporation of Ni and the subsequent annealing of the ZnO/Ni core/shell nanostructures. The core/shell NRs annealed at 400 °C showed superior crystalline and emission properties. More interestingly, with the increase of annealing temperature, the crystallinity of the Ni shells over the ZnO NRs gradually changed from polycrystalline to single crystalline. The presence of the Ni layer as a polycrystalline shell completely hindered the light emission and transmission of the ZnO NR cores. Further, the band gap of ZnO NRs continuously decreased with the increase of annealing temperature.

  13. Selective growth of hierarchical ZnO nanorod arrays on the graphene nanosheets

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Li, Lan; Li, Jinliang; Mo, Zhaojun

    2016-01-01

    We report directly selective-area grown (SAG) high-quality hierarchical ZnO nanorod arrays on the graphene nanosheets without invoking damage or introducing a catalyst. The SAG behavior in the non-catalytic growth mechanism is attributed to dangling bonds on the boundary edges of graphene nanosheets, which serve as the preferential adsorption and nucleation sites of ZnO nanorod. High densities of hierarchical ZnO nanorods show single-crystalline hexagonal wurtzite structure and are vertically well-aligned on the graphene nanosheets, with the diameter and the density strongly dependent on the growth temperature. Furthermore, no carbon impurity can be seen in the tips of the ZnO nanorods and also no carbon-related defect peak in the 10 K PL spectrum of ZnO nanorods. Our approach using a graphene-nanosheet substrate provides an efficient route for the growth of high-quality ZnO with a one-dimensional (1D) hierarchical nanostructure, which is highly desirable for fabricating 1D ZnO hybrid optoelectronic devices, particularly for a fast-response UV photodetector and highly-sensitive gas sensor.

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

    PubMed Central

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

    2014-01-01

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

  15. AlN nanorod and nanoneedle arrays prepared by chloride assisted chemical vapor deposition for field emission applications.

    PubMed

    Song, Xubo; Guo, Zhigang; Zheng, Jie; Li, Xingguo; Pu, Yikang

    2008-03-19

    Hexagonal AlN nanorod and nanoneedle arrays were synthesized through the direct reaction of AlCl(3) and NH(3) by chemical vapor deposition at about 750 °C. Both the AlN nanoneedle and nanorod samples were of wurtzite structure and grew preferentially along the c-axis. With an increase in the ratio of NH(3) to Ar, an evolution from nanorods to nanoneedles was observed. A growth model was proposed to explain the possible growth mechanism. Measurements in field emission show that AlN nanoneedle arrays have a much lower turn-on field (3.1 V µm(-1)) compared to nanorod arrays (15.3 V µm(-1)), due to their large curvature geometry. The AlN nanoneedle arrays have potential applications in many fields, such as electron-emitting nanodevices and field-emission-based flat-panel displays. PMID:21730560

  16. Synthesis and Characterization of Supported CuInSe2 Nanorod Arrays on Rigid Substrates

    NASA Astrophysics Data System (ADS)

    Zhang, Zhong-wei; Li, Ji; Liu, Ji-lei; Zhu, Chang-fei

    2011-02-01

    Copper indium diselenide nanorod arrays were electrodeposited on tungsten/silicon rigid substrates using porous anodic alumina as growth template. The porous anodic alumina templates were prepared by anodizing aluminum films which were sputtered onto the tungsten/silicon substrates. A selective chemical etching was used to penetrate the barrier layer at the bottom of the alumina channels before electrodeposition, which enables direct electrical and chemical contact with the underside substrate electrode. The as-deposited samples were annealed at 450 °C in vacuum. Scanning electron microscopy revealed that the nanorods were dense and compact with diameter of about 100 nm, length of approximate 1 μm, and the aspect ratio of 10. X-ray diffraction, micro-Raman spectroscopy, and high resolution transmission electron microscopy showed that chalcopyrite polycrystalline structure and high purity CuInSe2 nanorods were obtained. The grain size was large in the rod axial direction. Energy-dispersive X-ray spectroscopy showed the composition was nearly stoichiometric. The energy band gap of this nanorod arrays was analyzed by fundamental absorption spectrum and was evaluated to be 0.96 eV.

  17. Ion-assisted functional monolayer coating of nanorod arrays in hydrogen plasmas

    SciTech Connect

    Tam, E.; Levchenko, I.; Ostrikov, K.; Keidar, M.; Xu, S.

    2007-02-15

    Uniformity of postprocessing of large-area, dense nanostructure arrays is currently one of the greatest challenges in nanoscience and nanofabrication. One of the major issues is to achieve a high level of control in specie fluxes to specific surface areas of the nanostructures. As suggested by the numerical experiments in this work, this goal can be achieved by manipulating microscopic ion fluxes by varying the plasma sheath and nanorod array parameters. The dynamics of ion-assisted deposition of functional monolayer coatings onto two-dimensional carbon nanorod arrays in a hydrogen plasma is simulated by using a multiscale hybrid numerical simulation. The numerical results show evidence of a strong correlation between the aspect ratios and nanopattern positioning of the nanorods, plasma sheath width, and densities and distributions of microscopic ion fluxes. When the spacing between the nanorods and/or their aspect ratios are larger, and/or the plasma sheath is wider, the density of microscopic ion current flowing to each of the individual nanorods increases, thus reducing the time required to apply a functional monolayer coating down to 11 s for a 7-{mu}m-wide sheath, and to 5 s for a 50-{mu}m-wide sheath. The computed monolayer coating development time is consistent with previous experimental reports on plasma-assisted functionalization of related carbon nanostructures [B. N. Khare et al., Appl. Phys. Lett. 81, 5237 (2002)]. The results are generic in that they can be applied to a broader range of plasma-based processes and nanostructures, and contribute to the development of deterministic strategies of postprocessing and functionalization of various nanoarrays for nanoelectronic, biomedical, and other emerging applications.

  18. Ion-assisted functional monolayer coating of nanorod arrays in hydrogen plasmas

    NASA Astrophysics Data System (ADS)

    Tam, E.; Levchenko, I.; Ostrikov, K.; Keidar, M.; Xu, S.

    2007-02-01

    Uniformity of postprocessing of large-area, dense nanostructure arrays is currently one of the greatest challenges in nanoscience and nanofabrication. One of the major issues is to achieve a high level of control in specie fluxes to specific surface areas of the nanostructures. As suggested by the numerical experiments in this work, this goal can be achieved by manipulating microscopic ion fluxes by varying the plasma sheath and nanorod array parameters. The dynamics of ion-assisted deposition of functional monolayer coatings onto two-dimensional carbon nanorod arrays in a hydrogen plasma is simulated by using a multiscale hybrid numerical simulation. The numerical results show evidence of a strong correlation between the aspect ratios and nanopattern positioning of the nanorods, plasma sheath width, and densities and distributions of microscopic ion fluxes. When the spacing between the nanorods and/or their aspect ratios are larger, and/or the plasma sheath is wider, the density of microscopic ion current flowing to each of the individual nanorods increases, thus reducing the time required to apply a functional monolayer coating down to 11 s for a 7-μm-wide sheath, and to 5 s for a 50-μm-wide sheath. The computed monolayer coating development time is consistent with previous experimental reports on plasma-assisted functionalization of related carbon nanostructures [B. N. Khare et al., Appl. Phys. Lett. 81, 5237 (2002)]. The results are generic in that they can be applied to a broader range of plasma-based processes and nanostructures, and contribute to the development of deterministic strategies of postprocessing and functionalization of various nanoarrays for nanoelectronic, biomedical, and other emerging applications.

  19. Ion-assisted functional monolayer coating of nanorod arrays in hydrogen plasmas

    NASA Astrophysics Data System (ADS)

    Tam, E.; Levchenko, I.; Ostrikov, K.; Keidar, M.; Xu, S.

    2007-03-01

    Uniformity of postprocessing of large-area, dense nanostructure arrays is currently one of the greatest challenges in nanoscience and nanofabrication. One of the major issues is to achieve a high level of control in specie fluxes to specific surface areas of the nanostructures. As suggested by the numerical experiments in this work, this goal can be achieved by manipulating microscopic ion fluxes by varying the plasma sheath and nanorod array parameters. The dynamics of ion-assisted deposition of functional monolayer coatings onto two-dimensional carbon nanorod arrays in a hydrogen plasma is simulated by using a multiscale hybrid numerical simulation. The numerical results show evidence of a strong correlation between the aspect ratios and nanopattern positioning of the nanorods, plasma sheath width, and densities and distributions of microscopic ion fluxes. When the spacing between the nanorods and/or their aspect ratios are larger, and/or the plasma sheath is wider, the density of microscopic ion current flowing to each of the individual nanorods increases, thus reducing the time required to apply a functional monolayer coating down to 11s for a 7-μm-wide sheath, and to 5s for a 50-μm-wide sheath. The computed monolayer coating development time is consistent with previous experimental reports on plasma-assisted functionalization of related carbon nanostructures [B. N. Khare et al., Appl. Phys. Lett. 81, 5237 (2002)]. The results are generic in that they can be applied to a broader range of plasma-based processes and nanostructures, and contribute to the development of deterministic strategies of postprocessing and functionalization of various nanoarrays for nanoelectronic, biomedical, and other emerging applications.

  20. Low-Cost Substrates for High-Performance Nanorod Array LEDs

    SciTech Connect

    Sands, Timothy; Stach, Eric; Garcia, Edwin

    2009-04-30

    The completed project, entitled Low-Cost Substrates for High-Performance Nanorod LEDs, targeted the goal of a phosphor-free nanorod-based white LED with IQE > 50% across the spectrum from 450 nm to 600 nm on metallized silicon substrates. The principal achievements of this project included: Demonstration of (In,Ga)N nanopyramid heterostructures by a conventional OMVPE process. Verification of complete filtering of threading dislocations to yield dislocation-free pyramidal heterostructures. Demonstration of electroluminescence with a peak wavelength of ~600 nm from an (In,Ga)N nanopyramid array LED. Development of a reflective ZrN/AlN buffer layer for epitaxial growth of GaN films and GaN nanopyramid arrays on (111)Si.

  1. Tailoring the optical and hydrophobic property of zinc oxide nanorod by coating with amorphous graphene

    NASA Astrophysics Data System (ADS)

    Pahari, D.; Das, N. S.; Das, B.; Chattopadhyay, K. K.; Banerjee, D.

    2016-09-01

    Zinc oxide (ZnO) nanorods were synthesized at room temperature on potassium permanganate activated silicon and glass substrate by simple chemical method using zinc acetate as precursor. To modify the surface energy of the as prepared ZnO thin films the samples were coated with amorphous graphene (a-G) synthesized by un-zipping of chemically synthesized amorphous carbon nanotubes (a-CNTs). All the pure and coated samples were characterized by x-ray diffraction, field emission scanning electron microscope, Raman spectroscopy, and Fourier transformed infrared spectroscopy. The roughness analysis of the as prepared samples was done by atomic force microscopic analysis. The detail optical properties of all the samples were studied with the help of a UV-Visible spectrophotometer. The surface energy of the as prepared pure and coated samples was calculated by measuring the contact angle of two different liquids. It is seen that the water repellence of ZnO nanorods got increased after they are being coated with a-Gs. Also even after UV irradiation the contact angle remain same unlike the case for the uncoated sample where the contact angle gets decreased significantly after UV irradiation. Existing Cassie-Wenzel model has been employed along with the Owen's approach to determine the different components of surface energy.

  2. Time-dependent hydrophilicity of nickel nanorod arrays

    NASA Astrophysics Data System (ADS)

    Albarakati, Nahla; Ye, Dexian

    2014-03-01

    Wetting properties of metals are fundamentally important in applications such as catalysis, solar energy conversion, and fuel cells. Complete wetting of transition metal surfaces by water is ascertained due to their high surface energy. On flat metal surfaces, zero contact angles (CAs) can only be observed on ultra-clean metal surfaces, while finite CAs are measured as soon as the surface is contaminated. However, it is not clear whether or not the hydrophilicity of a nanostructured metal surface can be maintained. Here, we design a series of experiments to test the hydrophilicity of nickel nanorods with heights ranging from 50 to 600 nm. We observe that all of our samples are initially superhydrophilic, but reduce their hydrophilicity over a time period of three months. Airborne hydrocarbon is believed to be the reason for the reducing hydrophilicity. A theory based on the Cassie-Baxter model is constructed to explain our observations in experiment.

  3. Fabrication of porous TiO2 nanorod array photoelectrodes with enhanced photoelectrochemical water splitting by helium ion implantation.

    PubMed

    Liu, Yichao; Shen, Shaohua; Ren, Feng; Chen, Jianan; Fu, Yanming; Zheng, Xudong; Cai, Guangxu; Xing, Zhuo; Wu, Hengyi; Jiang, Changzhong

    2016-05-19

    Porous photoelectrodes show high efficiency in hydrogen production by water splitting. However, fabrication of porous nanorods is usually difficult. Here, we report a simple approach to fabricate a kind of novel porous rutile titanium dioxide nanorod array by an advanced ion implantation method using multiple-energy helium ion implantation and subsequent annealing. The porous nanostructure enhances the photoelectrochemical performance of the titanium dioxide nanorod array photoelectrodes under Uv-visible light illumination, where the highest photocurrent density was relatively about 10 times higher than that of the pristine titanium dioxide nanorod array. The formation of nanocavities mainly contributes to the enhancement of the photocurrent density by trapping holes inside to separate the charge carriers. The study demonstrates that ion implantation could be an effective approach to develop novel porous nanostructural photoelectrodes for the application of hydrogen production. PMID:27145900

  4. Raman spectroscopic investigation of the confined optical phonon modes in the aligned CdSe nanorod arrays

    NASA Astrophysics Data System (ADS)

    Nobile, Concetta; Carbone, Luigi; Kudera, Stefan; Manna, Liberato; Cingolani, Roberto; Krahne, Roman; Fonoberov, Vladimir A.; Balandin, Alexander A.; Chilla, Gerwin; Kipp, Tobias; Heitmann, Detlef

    2007-03-01

    Nanocrystal rods have emerged as promising nanostructured material for both fundamental studies of nanoscale effects and for optical and electronic device applications. We investigated the optical phonon excitations in laterally aligned CdSe nanocrystal rod arrays using resonant Raman scattering. Electric-field mediated alignment between interdigitated electrodes has been used to prepare the samples. We report Raman experiments that probe the optical lattice vibrations in ordered arrays of CdSe nanorods with respect to the nanorod orientation. The packing of nanorods into dense arrays leads to the suppression of the surface optical phonon modes. In the longitudinal-optical phonon peak we observe a fine structure that depends on the relative orientation of the nanorods with respect to the incident light polarization. Detailed comparison of the experimental data with the first-principle calculations for corresponding nanostructures, which reveal the symmetry of the phonon potentials for the Raman active modes, provides a qualitative explanation of the experimentally observed phonon modes.

  5. Ag nanoparticles-decorated ZnO nanorod array on a mechanical flexible substrate with enhanced optical and antimicrobial properties.

    PubMed

    Chen, Yi; Tse, Wai Hei; Chen, Longyan; Zhang, Jin

    2015-01-01

    Heteronanostructured zinc oxide nanorod (ZnO NR) array are vertically grown on polydimethylsiloxane (PDMS) through a hydrothermal method followed by an in situ deposition of silver nanoparticles (Ag NPs) through a photoreduction process. The Ag-ZnO heterostructured nanorods on PDMS are measured with an average diameter of 160 nm and an average length of 2 μm. ZnO NRs measured by high-resolution transmission electron microscope (HRTEM) shows highly crystalline with a lattice fringe of 0.255 nm, which corresponds to the (0002) planes in ZnO crystal lattice. The average diameter of the Ag NPs in situ deposited on the ZnO NRs is estimated at 22 ± 2 nm. As compared to the bare ZnO NRs, the heterostructured Ag-ZnO nanorod array shows enhanced ultraviolet (UV) absorption at 440 nm, and significant emission in the visible region (λem = 542 nm). In addition, the antimicrobial efficiency of Ag-ZnO heterostructured nanorod array shows obvious improvement as compared to bare ZnO nanorod array. The cytotoxicity of ZnO nanorod array with and without Ag NPs was studied by using 3 T3 mouse fibroblast cell line. No significant toxic effect is imposed on the cells. PMID:25852401

  6. Fabrication of porous TiO2 nanorod array photoelectrodes with enhanced photoelectrochemical water splitting by helium ion implantation

    NASA Astrophysics Data System (ADS)

    Liu, Yichao; Shen, Shaohua; Ren, Feng; Chen, Jianan; Fu, Yanming; Zheng, Xudong; Cai, Guangxu; Xing, Zhuo; Wu, Hengyi; Jiang, Changzhong

    2016-05-01

    Porous photoelectrodes show high efficiency in hydrogen production by water splitting. However, fabrication of porous nanorods is usually difficult. Here, we report a simple approach to fabricate a kind of novel porous rutile titanium dioxide nanorod array by an advanced ion implantation method using multiple-energy helium ion implantation and subsequent annealing. The porous nanostructure enhances the photoelectrochemical performance of the titanium dioxide nanorod array photoelectrodes under Uv-visible light illumination, where the highest photocurrent density was relatively about 10 times higher than that of the pristine titanium dioxide nanorod array. The formation of nanocavities mainly contributes to the enhancement of the photocurrent density by trapping holes inside to separate the charge carriers. The study demonstrates that ion implantation could be an effective approach to develop novel porous nanostructural photoelectrodes for the application of hydrogen production.Porous photoelectrodes show high efficiency in hydrogen production by water splitting. However, fabrication of porous nanorods is usually difficult. Here, we report a simple approach to fabricate a kind of novel porous rutile titanium dioxide nanorod array by an advanced ion implantation method using multiple-energy helium ion implantation and subsequent annealing. The porous nanostructure enhances the photoelectrochemical performance of the titanium dioxide nanorod array photoelectrodes under Uv-visible light illumination, where the highest photocurrent density was relatively about 10 times higher than that of the pristine titanium dioxide nanorod array. The formation of nanocavities mainly contributes to the enhancement of the photocurrent density by trapping holes inside to separate the charge carriers. The study demonstrates that ion implantation could be an effective approach to develop novel porous nanostructural photoelectrodes for the application of hydrogen production. Electronic

  7. Gold Nanorods: Evaporative Self-Assembly of Gold Nanorods into Macroscopic 3D Plasmonic Superlattice Arrays (Adv. Mater. 13/2016).

    PubMed

    Li, Penghui; Li, Yong; Zhou, Zhang-Kai; Tang, Siying; Yu, Xue-Feng; Xiao, Shu; Wu, Zhongzhen; Xiao, Quanlan; Zhao, Yuetao; Wang, Huaiyu; Chu, Paul K

    2016-04-01

    On page 2511, X.-F. Yu, P. K. Chu, and co-workers demonstrate the successful fabrication of millimeter-scale three-dimensional superlattice arrays consisting of dense, regular, and vertically aligned gold nanorods by the evaporative self-assembly method. The excellent performance in surface-enhanced Raman scattering indicates applications in plasmonic substrates. PMID:27037942

  8. Multilayer TiO2 nanorod cloth/nanorod array electrode for dye-sensitized solar cells and self-powered UV detectors.

    PubMed

    Wang, Zhuoran; Ran, Sihan; Liu, Bin; Chen, Di; Shen, Guozhen

    2012-06-01

    A multilayer TiO(2) nanorod-assembled cloth/nanorod array based electrode was fabricated by transferring different layers of TiO(2) nanorod-assembled cloth (TNRC) onto nanorod array grown on the conducting FTO substrate (titania nanorod, TNR). Combining the superior electron transport characteristics of TNR and outstanding optical properties of TNRC, the nanostructured electrode composed of two layers of TNRC meets the optimized design for high quality dye-sensitized solar cells (DSCs) and self-powered UV detectors. The highest efficiency of 4.02% for DSC under AM 1.5 was achieved with a high short circuit current density of 9.81 mA cm(-2), which was proved to be owing to the enhanced dye anchoring, light scattering and reduced charge recombination. For the photoelectrochemical (PEC) UV detector, the highest quantum efficiency of over 46% was obtained and a high photocurrent response of 0.271 mA cm(-2) was observed, together with the excellent self-powered, fast response and "visible blind" characteristics. A perfect linear response to the changed low-power signal indicates great potential for practical applications. PMID:22549639

  9. Aligned ZnO nanorod arrays growth on GaN QDs for excellent optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Sang, Dandan; Li, Hongdong; Wang, Qinglin

    2016-02-01

    Uniformly aligned ZnO nanorod (NR) arrays grown on GaN quantum dots (QDs) as preferred nucleation sites are imperative for designing field emission emitters, ultraviolet photodetectors and light-emitting diodes for a wide range of new optoelectronic applications. In a recent study (2015 Nanotechnology 26 415601), Qi et al reported a novel method of fabricating ZnO NRs arrays with uniform shape, the density of which is easily tunable by adjusting the density of GaN QDs. This approach opens a door to obtaining a combination of 0D and 1D structures for optoelectronic applications.

  10. Photoelectrochemical Properties of Vertically Aligned CuInS2 Nanorod Arrays Prepared via Template-Assisted Growth and Transfer.

    PubMed

    Yang, Wooseok; Oh, Yunjung; Kim, Jimin; Kim, Hyunchul; Shin, Hyunjung; Moon, Jooho

    2016-01-13

    Although copper-based chalcopyrite materials such as CuInS2 have been considered promising photocathodes for solar water splitting, the fabrication route for a nanostructure with vertical orientation has not yet been developed. Here, a fabrication route for vertically aligned CuInS2 nanorod arrays from an aqueous solution using anodic aluminum oxide template-assisted growth and transfer is presented. The nanorods exhibit a phase-pure CuInS2 chalcopyrite structure and cathodic photocurrent response without co-catalyst loading. Small particles of CdS and ZnS were conformally decorated onto CuInS2 nanorods using a successive ion layer adsorption and reaction method. With surface modification of CdS/ZnS, the photoelectrochemical properties of CuInS2 nanorod arrays are enhanced via flat-band potential shift, as determined by analyses of onset potential and Mott-Schottky plots. PMID:26645722

  11. Parallel collective resonances in arrays of gold nanorods.

    PubMed

    Vitrey, Alan; Aigouy, Lionel; Prieto, Patricia; García-Martín, José Miguel; González, María U

    2014-01-01

    In this work we discuss the excitation of parallel collective resonances in arrays of gold nanoparticles. Parallel collective resonances result from the coupling of the nanoparticles localized surface plasmons with diffraction orders traveling in the direction parallel to the polarization vector. While they provide field enhancement and delocalization as the standard collective resonances, our results suggest that parallel resonances could exhibit greater tolerance to index asymmetry in the environment surrounding the arrays. The near- and far-field properties of these resonances are analyzed, both experimentally and numerically. PMID:24645987

  12. Morphological and structural characterization of single-crystal ZnO nanorod arrays on flexible and non-flexible substrates

    PubMed Central

    Farhat, Omar F; Halim, Mohd M; Abdullah, Mat J; Ali, Mohammed K M

    2015-01-01

    Summary We report a facile synthesis of zinc oxide (ZnO) nanorod arrays using an optimized, chemical bath deposition method on glass, PET and Si substrates. The morphological and structural properties of the ZnO nanorod arrays were investigated using various techniques such as field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) measurements, which revealed the formation of dense ZnO nanorods with a single crystal, hexagonal wurtzite structure. The aspect ratio of the single-crystal ZnO nanorods and the growth rate along the (002) direction was found to be sensitive to the substrate type. The lattice constants and the crystallite size of the fabricated ZnO nanorods were calculated based on the XRD data. The obtained results revealed that the increase in the crystallite size is strongly associated with the growth conditions with a minor dependence on the type of substrate. The Raman spectroscopy measurements confirmed the existence of a compressive stress in the fabricated ZnO nanorods. The obtained results illustrated that the growth of high quality, single-crystal ZnO nanorods can be realized by adjusting the synthesis conditions. PMID:25821712

  13. Hydrothermal synthesis of highly crystalline ZnO nanorod arrays: Dependence of morphology and alignment on growth conditions

    NASA Astrophysics Data System (ADS)

    Azzez, Shrook A.; Hassan, Z.; Hassan, J. J.; Alimanesh, M.; Rasheed, Hiba S.; Sabah, Fayroz A.; Abdulateef, Sinan A.

    2016-07-01

    Highly oriented zinc oxide nanorod were successfully grown on seeded p-type silicone substrate by hydrothermal methode. The morphology and the crystallinty of ZnO c-axis (002) arrays were systematically studied using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) methods. The effect of seed layer pre-annealing on nanorods properties was explained according to the nucleation site of ZnO nanoparticles on silicon substrate. In addition, the variation of the equal molarity of zinc nitrate hexahydrate and hexamine concentrations in the reaction vessel play a crucial role related to the ZnO nanorods.

  14. Bunched akaganeite nanorod arrays: Preparation and high-performance for flexible lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Peng, Shaomin; Yu, Lin; Sun, Ming; Cheng, Gao; Lin, Ting; Mo, Yudi; Li, Zishan

    2015-11-01

    Significant effort has been made to explore high-performance anode materials for flexible lithium-ion batteries. We report a facile hydrothermal route to synthesis self-organized bunched akaganeite (β-FeOOH) nanorod arrays directly grown on carbon cloth (CC/β-FeOOH NRAs). Interestingly, the single nanorod is assembled by numerous small nanowires. A possible growth mechanism for this unique structure is proposed. Owning to the essential crystal structure of β-FeOOH (body-centered cubic), porous morphology, high surface area and direct growth on current collector, the prepared CC/β-FeOOH NRAs manifest a very high reversible capacity of ≈2840 mAh g-1 (2.21 mAh cm-2), remarkable rate capability 568 mAh g-1 (0.43 mAh cm-2) at 10C, stable cycling performance and greater mechanical strength.

  15. Surface diffusion driven morphological instability in free-standing nickel nanorod arrays

    SciTech Connect

    Alrashid, Ebtihaj; Ye, Dexian

    2014-07-28

    Metallic nanostructures are thermodynamically unstable due to the excess of energy of large numbers of surface atoms. Morphological instability, such as Rayleigh breakup, sintering, and coalescence, can be observed at a temperature much lower than the bulk melting point of the metal. We study the morphological and crystalline evolution of well-aligned free-standing nickel nanorod arrays at elevated temperatures up to 600 °C. The as-deposited nickel nanorods are faceted with sharp nanotips, which are deformed at annealing temperatures higher than 400 °C due to strong surface diffusion. A mud-crack like pattern is formed in the samples annealed above 400 °C, leading to the generation of interconnected porous structure. Meanwhile, the X-ray diffraction reveals the recrystallization of nickel nanocrystals when annealed from 300 to 600 °C.

  16. Phased laser array with tailored spectral and coherence properties

    DOEpatents

    Messerly, Michael J; Dawson, Jay W; Beach, Raymond J

    2011-03-29

    Architectures for coherently combining an array of fiber-based lasers are provided. By matching their lengths to within a few integer multiples of a wavelength, the spatial and temporal properties of a single large laser are replicated, while extending the average or peak pulsed power limit.

  17. Phased laser array with tailored spectral and coherence properties

    SciTech Connect

    Messerly, Michael J; Dawson, Jay W; Beach, Raymond J

    2014-05-20

    Architectures for coherently combining an array of fiber-based lasers are provided. By matching their lengths to within a few integer multiples of a wavelength, the spatial and temporal properties of a single large laser are replicated, while extending the average or peak pulsed power limit.

  18. Chemical growth of ZnO nanorod arrays on textured nanoparticle nanoribbons and its second-harmonic generation performance

    NASA Astrophysics Data System (ADS)

    Gui, Zhou; Wang, Xian; Liu, Jian; Yan, Shanshan; Ding, Yanyan; Wang, Zhengzhou; Hu, Yuan

    2006-07-01

    On the basis of the highly oriented ZnO nanoparticle nanoribbons as the growth seed layer (GSL) and solution growth technique, we have synthesized vertical ZnO nanorod arrays with high density over a large area and multi-teeth brush nanostructure, respectively, according to the density degree of the arrangement of nanoparticle nanoribbons GSL on the glass substrate. This controllable and convenient technique opens the possibility of creating nanostructured film for industrial fabrication and may represent a facile way to get similar structures of other compounds by using highly oriented GSL to promote the vertical arrays growth. The growth mechanism of the formation of the ordered nanorod arrays is also discussed. The second-order nonlinear optical coefficient d31 of the vertical ZnO nanorod arrays measured by the Maker fringes technique is 11.3 times as large as that of d36 KH 2PO 4 (KDP).

  19. Large-scale growth of density-tunable aligned ZnO nanorods arrays on GaN QDs

    NASA Astrophysics Data System (ADS)

    Qi, Zhiqiang; Li, Senlin; Sun, Shichuang; Zhang, Wei; Ye, Wei; Fang, Yanyan; Tian, Yu; Dai, Jiangnan; Chen, Changqing

    2015-10-01

    An effective approach for growing large-scale, uniformly aligned ZnO nanorods arrays is demonstrated. The synthesis uses a GaN quantum dot (QD) template produced by a self-assembled Stranski-Krastanow mode in metal organic chemical vapor deposition, which serves as a nucleation site for ZnO owing to the QD’s high surface free energy. The resultant ZnO nanorods with uniform shape and length align vertically on the template, while their density is easily tunable by adjusting the density of GaN QDs, which can be adjusted by simply varying growth interruption. By controlling the density of ZnO nanorod arrays, their optical performance can also be improved. This approach opens the possibility of combining one-dimensional (1D) with 0D nanostructures for applications in sensor arrays, piezoelectric antenna arrays, optoelectronic devices, and interconnects.

  20. A Hierarchically Ordered Array of Silver-Nanorod Bundles for Surface-Enhanced Raman Scattering Detection of Phenolic Pollutants.

    PubMed

    Zhu, Chuhong; Meng, Guowen; Zheng, Peng; Huang, Qing; Li, Zhongbo; Hu, Xiaoye; Wang, Xiujuan; Huang, Zhulin; Li, Fadi; Wu, Nianqiang

    2016-06-01

    A hierarchically ordered array of Ag-nanorod bundles is achieved using an inexpensive binary-template-assisted electrodeposition technique. In every bundle, many small gaps are formed between adjacent Ag-nanorods, where "hot spots" are generated. As a result, this plasmonic nanostructure exhibits SERS enhancements of approximately eight orders of magnitude with uniform and reproducible SERS signal throughout the whole chip. PMID:27112639

  1. Structure-thermal property correlation of aligned silicon dioxide nanorod arrays

    NASA Astrophysics Data System (ADS)

    Zhu, Jie; Zhu, Yu; Wu, Xuewang; Song, Helun; Zhang, Yaohui; Wang, Xiaojia

    2016-06-01

    Quantitative characterization of thermal properties of nanorod (NR) arrays appears to be challenging due to the complex combination of high volume of air voids, anisotropy, and structural non-uniformity. This work investigates the structure-thermal property correlation of arrays consisting of either vertically aligned or slanted silicon dioxide (SiO2) NRs, fabricated by the dynamic shadowing growth technique. We apply the frequency-dependent time-domain thermoreflectance method to quantify the thermal properties of SiO2 NR arrays that may possess inhomogeneity along the depth direction. The effective thermal conductivities of four SiO2 NR array films and one reference capping layer for the SiO2 NR array are obtained. The impact of the structure on the effective thermal conductivities of the SiO2 NR array is discussed. The lowest effective thermal conductivity among all samples in this work is found to be 0.13 W m-1 K-1 for the slanted NR array. We attribute the reduction in the effective thermal conductivity of the NR array to the discontinuous nature of SiO2 NRs, which reduces the density of the thermal transport channels and thus prevents heat flux from propagating downwards along the through-plane direction. The results from this work facilitate the potential applications of NR-array-based thermal insulators for micro-thermal devices.

  2. Microfluidic-based metal enhanced fluorescence for capillary electrophoresis by Ag nanorod arrays

    NASA Astrophysics Data System (ADS)

    Xiao, Chenyu; Cao, Zhen; Deng, Junhong; Huang, Zhifeng; Xu, Zheng; Fu, Junxue; Yobas, Levent

    2014-06-01

    As metal nanorods show much higher metal enhanced fluorescence (MEF) than metal nanospheres, microfluidic-based MEF is first explored with Ag nanorod (ND) arrays made by oblique angle deposition. By measuring the fluorescein isothiocyanate (FITC) solution sandwiched between the Ag NDs and a piece of cover slip, the enhancement factors (EFs) are found as 3.7 ± 0.64 and 6.74 ± 2.04, for a solution thickness at 20.8 μm and 10 μm, respectively. Because of the strong plasmonic coupling between the adjacent Ag NDs, only the emission of the fluorophores present in the three-dimensional NDs array gets enhanced. Thus, the corresponding effective enhancement factors (EEFs) are revealed to be relatively close, 259 ± 92 and 340 ± 102, respectively. To demonstrate the application of MEF in microfluidic systems, a multilayer of SiO2 NDs/Ag NDs is integrated with a capillary electrophoresis device. At a microchannel depth of 10 μm, an enhancement of 6.5 fold is obtained for amino acids separation detection. These results are very encouraging and open the possibility of MEF applications for the Ag ND arrays decorated microchannels. With the miniaturization of microfluidic devices, microfluidic-based MEF by Ag ND arrays will likely find more applications with further enhancement.

  3. Novel Gas Sensor Based on ZnO Nanorod Circular Arrays for C2H5OH Gas Detection.

    PubMed

    Jianjiao, Zhang; Hongyan, Yue; Erjun, Guo; Shaolin, Zhang; Liping, Wang; Chunyu, Zhang; Xin, Gao; Jing, Chang; Hong, Zhang

    2015-03-01

    Novel side-heating gas sensor based on ZnO nanorod circular arrays was firstly fabricated by hydrothermal treatment assisted with a kind of simple dip-coating technique. The structure and morphologies of ZnO nanorods were characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), respectively. XRD result indicates that the obtained ZnO nanorods have good crystalline with the hexagonal wurtzite structure. SEM result indicates that ZnO nanorod arrays are vertically growth on the surface of ceramic tube of side-heating sensor with controlled diameter and length, narrow size distribution and high orientation. The gas sensing properties of ZnO nanorod circular arrays are also evaluated. Comparative to the sensor based on scattered ZnO nanorods responding to 25 ppm H2, CO, C6H5CH3 and C2H5OH gas, respectively, the sensing values of high orientation gas sensor are generally increased by 5%. This novel sensor has good application promising for the fabrication of cost effective and high performance gas sensors. PMID:26413689

  4. Direct growth of tellurium nanorod arrays on Pt/FTO/glass through a surfactant-assisted chemical reduction.

    PubMed

    Liu, Hongmei; Zeng, Boming; Jia, Falong

    2011-07-29

    Uniform tellurium nanorod arrays (TNA) have been successfully deposited directly on Pt/FTO (F-doped SnO(2))/glass substrate through a facile surfactant-assisted approach, which involved chemical reduction of TeO(3)(2-) ions by hydrazine hydrate. The whole synthesis process is highly repeatable and performed simply by immersing the Pt/FTO/glass in the solution for a certain time. During the growth of TNA, Pt catalyzed the reduction of TeO(3)(2-) ions by hydrazine hydrate and Te nanoparticles were deposited firmly on the substrate at first. Then, under the regulation of the surfactant (cetyltrimethylammonium bromide, CTAB), the deposited Te grew into nanorod arrays and adhered firmly to the substrate. Similar Te nanorod arrays could also grow on a Pd substrate which has the same catalytic performance as that of Pt. The as-synthesized TNA could be used as a good template to synthesize platinum-and gold-coated nanorods through convenient galvanic replacement. As a demonstration of potential application, the gold/tellurium nanorods showed uniform surface-enhanced Raman scattering (SERS) using rhodamine 6G (Rh6G) as the analyte. This approach provides a simple route for the growth of standing Te nanorods on a substrate, which may be used for the synthesis of other standing one-dimensional materials through a similar mechanism. PMID:21719969

  5. Direct growth of tellurium nanorod arrays on Pt/FTO/glass through a surfactant-assisted chemical reduction

    NASA Astrophysics Data System (ADS)

    Liu, Hongmei; Zeng, Boming; Jia, Falong

    2011-07-01

    Uniform tellurium nanorod arrays (TNA) have been successfully deposited directly on Pt/FTO (F-doped SnO2)/glass substrate through a facile surfactant-assisted approach, which involved chemical reduction of TeO32 - ions by hydrazine hydrate. The whole synthesis process is highly repeatable and performed simply by immersing the Pt/FTO/glass in the solution for a certain time. During the growth of TNA, Pt catalyzed the reduction of TeO32 - ions by hydrazine hydrate and Te nanoparticles were deposited firmly on the substrate at first. Then, under the regulation of the surfactant (cetyltrimethylammonium bromide, CTAB), the deposited Te grew into nanorod arrays and adhered firmly to the substrate. Similar Te nanorod arrays could also grow on a Pd substrate which has the same catalytic performance as that of Pt. The as-synthesized TNA could be used as a good template to synthesize platinum-and gold-coated nanorods through convenient galvanic replacement. As a demonstration of potential application, the gold/tellurium nanorods showed uniform surface-enhanced Raman scattering (SERS) using rhodamine 6G (Rh6G) as the analyte. This approach provides a simple route for the growth of standing Te nanorods on a substrate, which may be used for the synthesis of other standing one-dimensional materials through a similar mechanism.

  6. A self-powered UV photodetector based on TiO2 nanorod arrays

    PubMed Central

    2013-01-01

    Large-area vertical rutile TiO2 nanorod arrays (TNAs) were grown on F/SnO2 conductive glass using a hydrothermal method at low temperature. A self-powered ultraviolet (UV) photodetector based on TiO2 nanorod/water solid–liquid heterojunction is designed and fabricated. These nanorods offer an enlarged TiO2/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. A photosensitivity of 0.025 A/W and a quick response time were observed. At the same time, a high photosensitivity in a wide range of wavelength was also demonstrated. This TNA/water UV detector can be a particularly suitable candidate for practical applications for its high photosensitivity, fast response, excellent spectral selectivity, uncomplicated low-cost fabrication process, and environment-friendly feature. PMID:23618012

  7. Silver-Overgrowth-Induced Changes in Intrinsic Optical Properties of Gold Nanorods: From Noninvasive Monitoring of Growth Kinetics to Tailoring Internal Mirror Charges

    PubMed Central

    2015-01-01

    We investigate the effect of surfactant-mediated, asymmetric silver overgrowth of gold nanorods on their intrinsic optical properties. From concentration-dependent experiments, we established a close correlation of the extinction in the UV/vis/NIR frequency range and the morphological transition from gold nanorods to Au@Ag cuboids. Based on this correlation, a generic methodology for in situ monitoring of the evolution of the cuboid morphology was developed and applied in time-dependent experiments. We find that growth rates are sensitive to the substitution of the surfactant headgroup by comparison of benzylhexadecyldimethylammonium chloride (BDAC) with hexadecyltrimethylammonium chloride (CTAC). The time-dependent overgrowth in BDAC proceeds about 1 order of magnitude slower than in CTAC, which allows for higher control during silver overgrowth. Furthermore, silver overgrowth results in a qualitatively novel optical feature: Upon excitation inside the overlap region of the interband transition of gold and intraband of silver, the gold core acts as a retarding element. The much higher damping of the gold core compared to the silver shell in Au@Ag cuboids induces mirror charges at the core/shell interface as shown by electromagnetic simulations. Full control over the kinetic growth process consequently allows for precise tailoring of the resonance wavelengths of both modes. Tailored and asymmetric silver-overgrown gold nanorods are of particular interest for large-scale fabrication of nanoparticles with intrinsic metamaterial properties. These building blocks could furthermore find application in optical sensor technology, light harvesting, and information technology. PMID:26113885

  8. All-optical, polarization-insensitive light tuning properties in silver nanorod arrays covered with photoresponsive liquid crystals.

    PubMed

    Si, Guangyuan; Leong, Eunice S P; Jiang, Xiaoxiao; Lv, Jiangtao; Lin, Jiao; Dai, Haitao; Liu, Yan Jun

    2015-05-28

    Active plasmonics has been an interesting and important topic recently. Here we demonstrate the all-optical, polarization-insensitive tunable manipulation of a hybrid system that integrates a silver nanorod array with photoresponsive liquid crystals. The large-area plasmonic nanorod arrays are fabricated by laser interference lithography and ion milling. By covering a layer of photoresponsive liquid crystals, tunable control of plasmon resonance is achieved under an external light pump. The silver nanorod array also enables the homeotropic alignment of the liquid crystals, which makes the all-optical tuning behavior polarization-insensitive. With its advantages of cost-effective fabrication, easy integration, all-optical control, and polarization-insensitivity, the hybrid system could be valuable in many nanophotonic applications. PMID:25758775

  9. Seedless Pattern Growth of Quasi-Aligned ZnO Nanorod Arrays on Cover Glass Substrates in Solution

    NASA Astrophysics Data System (ADS)

    Ahsanulhaq, Q.; Kim, Jin Hwan; Kim, Jeong Hyun; Hahn, Y. B.

    2010-03-01

    A hybrid technique for the selective growth of ZnO nanorod arrays on wanted areas of thin cover glass substrates was developed without the use of seed layer of ZnO. This method utilizes electron-beam lithography for pattern transfer on seedless substrate, followed by solution method for the bottom-up growth of ZnO nanorod arrays on the patterned substrates. The arrays of highly crystalline ZnO nanorods having diameter of 60 ± 10 nm and length of 750 ± 50 nm were selectively grown on different shape patterns and exhibited a remarkable uniformity in terms of diameter, length, and density. The room temperature cathodluminescence measurements showed a strong ultraviolet emission at 381 nm and broad visible emission at 585-610 nm were observed in the spectrum.

  10. A novel method to encapsulate a Au nanorod array in 15 nm radius multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Liao, Gaomin; Pan, Yuanyuan; Wu, Qiang; Li, Shaoyun; Weng, Yuyan; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Tsui, Ophelia K. C.

    2014-11-01

    In this paper we demonstrate a novel complex array structure comprising well-aligned Au nanorods (10 nm in diameter) encapsulated inside 15 nm radius multiwalled carbon nanotubes (MWCNTs). A pre-aligned and open-ended nanoporous MWCNT membrane is used as the starting material. Au nanorods are precisely deposited and aligned inside the hollow channels of CNTs by inter-diffusing the HAuCl4 precursor and the reductant solution. Ultra-long Au nanowires and spherical Au nanoparticles are also observed in the CNT cavity with the same diameter in special cases. Using high-resolution TEM (HRTEM), scanning transmission electron microscopy (STEM), 3-dimensional TEM (3D-TEM) and energy dispersive X-ray spectroscopy (EDX), the precise location and composition of the encapsulated Au components with various structures are confirmed. This aligned Au@CNT endohedral material has important potential applications in nanocatalysis, waveguides, as well as in novel plasmonic devices.In this paper we demonstrate a novel complex array structure comprising well-aligned Au nanorods (10 nm in diameter) encapsulated inside 15 nm radius multiwalled carbon nanotubes (MWCNTs). A pre-aligned and open-ended nanoporous MWCNT membrane is used as the starting material. Au nanorods are precisely deposited and aligned inside the hollow channels of CNTs by inter-diffusing the HAuCl4 precursor and the reductant solution. Ultra-long Au nanowires and spherical Au nanoparticles are also observed in the CNT cavity with the same diameter in special cases. Using high-resolution TEM (HRTEM), scanning transmission electron microscopy (STEM), 3-dimensional TEM (3D-TEM) and energy dispersive X-ray spectroscopy (EDX), the precise location and composition of the encapsulated Au components with various structures are confirmed. This aligned Au@CNT endohedral material has important potential applications in nanocatalysis, waveguides, as well as in novel plasmonic devices. Electronic supplementary information (ESI

  11. a High-Performance Glucose Biosensor Based on Zno Nanorod Arrays Modified with AU Nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Gong; Lei, Yang; Yan, Xiaoqin

    2012-08-01

    An amperometric glucose biosensor based on vertically aligned ZnO nanorod (NR) arrays modified with Au nanoparticles (NPs) was constructed in a channel-limited way. Au NPs with diameters in the range of 8-10 nm have been successfully synthesized by photoreduction method and were uniformly loaded onto the surface of ZnO NRs that was hydrothermally deposited on the Fluorine doped SnO2 conductive glass (FTO) via electrostatic self-assembly technique. The morphology and structure of Au/ZnO NR arrays were characterized by field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectrum analyzer (XPS). The electrocatalytic properties of glucose oxidase (GOD)- immobilized Au/ZnO NR arrays were evaluated by amperometry. Compared with the biosensor based on ZnO NR arrays, the resulting Au/ZnO NR arrays modified biosensor exhibited an expanded linear range from 3 μM to 3 mM with the detection limit of 30 nM and a smaller Michaelis-Menten constant of 0.7836 mM. All these results suggest that the Au NPs can greatly improve the biosensing properties of ZnO NR arrays and therefore Au/ZnO NR arrays provide a promising material for the biosensor designs and other biological applications.

  12. The monolithic lawn-like CuO-based nanorods array used for diesel soot combustion under gravitational contact mode.

    PubMed

    Yu, Yifu; Meng, Ming; Dai, Fangfang

    2013-02-01

    A simple and feasible contact mode called gravitational contact mode (GCM) was developed for the first time to imitate the practical state between soot and catalyst. By simulating rainwater adsorption on a lawn in nature, we synthesized a lawn-like CuO nanorods array, which exhibited rather good catalytic activity for diesel soot combustion under GCM. Moreover, the CuO nanorods array could serve as a support for composite catalysts through a sequential chemical bath deposition method and exhibited higher catalytic activity than a traditional supported catalyst. The monolithic macroscopic structure of such a catalyst shows its potential for large-scale preparation and application. PMID:23254389

  13. Study of the structural and luminescent properties of ZnO nanorod arrays with hydrogen peroxide treatment

    NASA Astrophysics Data System (ADS)

    Su, Wen-Yan; Lin, Ching-Fuh

    2008-08-01

    One-dimensional nanostructures, such as nanowires, nanoneedles, nanobelts and nanotubes, have been extensively studied in recent years. These fascinating structures have the excellent physical properties owing to their geometry with high aspect ratio and modify the light-matter interaction. However, the defects of these structures are the obstacles for the practical applications. We report the influence of the hydrogen peroxide (H2O2) treatment on the point defects and structural defects of ZnO nanorods grown on n-type silicon. The ZnO nanorod arrays are prepared by low-cost hydrothermal method and the H2O2 treatments are investigated in two different approaches. One is to immerse ZnO nanorod samples into H2O2 solution. The other is a pre-treatment of spin-coating H2O2 solution on the seed layer before the growth of the ZnO nanorods. In the first approach, we found that the ultraviolet (UV) emission peak of the ZnO nanorods photoluminescence (PL) spectra was strongly dependent on the immersion time. In the second approach, the H2O2 solution not only influences the quality of the seed layer, but also the amount of the oxygen interstitial defects in the ZnO nanorods grown thereon. As a result, the UV emission intensity from the ZnO nanorods is enhanced almost five times. These effects are attributed to oxygen desorption through oxidation-reduction reactions of hydrogen peroxide on the ZnO surface. The ZnO nanorod arrays with few oxygen interstitial defects are prepared by low-cost and low-temperature hydrogen peroxide treatments, which are compatible with glass and polymer substrates and expected to enable the fabrication of optoelectronic device with excellent performance.

  14. Plasmonic nanorod arrays of a two-segment dimer and a coaxial cable with 1 nm gap for large field confinement and enhancement

    NASA Astrophysics Data System (ADS)

    Cheng, Zi-Qiang; Nan, Fan; Yang, Da-Jie; Zhong, Yu-Ting; Ma, Liang; Hao, Zhong-Hua; Zhou, Li; Wang, Qu-Quan

    2015-01-01

    Seeking plasmonic nanostructures with large field confinement and enhancement is significant for photonic and electronic nanodevices with high sensitivity, reproducibility, and tunability. Here, we report the synthesis of plasmonic arrays composed of two-segment dimer nanorods and coaxial cable nanorods with ~1 nm gap insulated by a self-assembled Raman molecule monolayer. The gap-induced plasmon coupling generates an intense field in the gap region of the dimer junction and the cable interlayer. As a result, the longitudinal plasmon resonance of nanorod arrays with high tunability is obviously enhanced. Most interestingly, the field enhancement of dimer nanorod arrays can be tuned by the length ratio L1/L2 of the two segments, and the maximal enhancement appears at L1/L2 = 1. In that case, the two-photon luminescence (TPL) of dimer nanorod arrays and the Raman intensity in the dimer junction is enhanced by 27 and 30 times, respectively, under resonant excitation. In the same way, the Raman intensity in the gap region is enhanced 16 times for the coaxial cable nanorod arrays. The plasmonic nanorod arrays synthesized by the facile method, having tunable plasmon properties and large field enhancement, indicate an attractive pathway to the photonic nanodevices.Seeking plasmonic nanostructures with large field confinement and enhancement is significant for photonic and electronic nanodevices with high sensitivity, reproducibility, and tunability. Here, we report the synthesis of plasmonic arrays composed of two-segment dimer nanorods and coaxial cable nanorods with ~1 nm gap insulated by a self-assembled Raman molecule monolayer. The gap-induced plasmon coupling generates an intense field in the gap region of the dimer junction and the cable interlayer. As a result, the longitudinal plasmon resonance of nanorod arrays with high tunability is obviously enhanced. Most interestingly, the field enhancement of dimer nanorod arrays can be tuned by the length ratio L1/L2 of

  15. Output power enhancement from ZnO nanorods piezoelectric nanogenerators by Si microhole arrays

    NASA Astrophysics Data System (ADS)

    Baek, Seong-Ho; Roqibul Hasan, Md; Park, Il-Kyu

    2016-02-01

    We demonstrate the enhancement of output power from a ZnO nanorod (NR)-based piezoelectric nanogenerator by using Si microhole (Si-μH) arrays. The depth-controlled Si-μH arrays were fabricated by using the deep reactive ion etching method. The ZnO NRs were grown along the Si-μH surface, in holes deeper than 20 μm. The polymer layer, polydimethylsiloxane, which acts a stress diffuser and electrical insulator, was successfully penetrated into the deep Si-μH arrays. Optical investigations show that the crystalline quality of the ZnO NRs on the Si-μH arrays was not degraded, even though they were grown on the deeper Si-μH arrays. As the depth of the Si-μH arrays increase from 0 to 20 μm, the output voltage was enhanced by around 8.1 times while the current did not increase. Finally, an output power enhancement of ten times was obtained. This enhancement of the output power was consistent with the increase in the surface area, and was mainly attributed to the accumulation of the potentials generated by the series-connected ZnO NR-based nanogenerators, whose number increases as the depth of the Si-μH increases.

  16. Two-step wetting transition on ZnO nanorod arrays

    NASA Astrophysics Data System (ADS)

    Luo, H.; Ma, J.; Wang, P.; Bai, J.; Jing, G.

    2015-08-01

    Transition between superhydrophilicity and superhydrophobicity is primarily important in the modification of the wettability of the material surface. The significant transition between the superhydrophilicity and the superhydrophobicity is realized from the surface made up of zinc oxide (ZnO) nanorod arrays on a silicon substrate with different annealing temperatures by the post-annealing process. Surprisingly, a critical temperature (300 °C) existed for ZnO nanorod arrays to achieve the transition from the increase in contact angle to its reduction. As the annealing temperature increases, the initial hydrophilic surface is gradually converted to the superhydrophobic one, whereas the surface property reverses back to the hydrophilic one as the critical annealing temperature is surpassed. Oxygen vacancies and carbon adsorptions are examined to be responsible for this extraordinary wettability variation. We establish a simple theoretical model to describe the novel mechanism of the transition between the superhydrophilicity and the superhydrophobicity. The facile method to achieve the transition reported here will supply the great facile applications to control the wetting properties of materials, without employing the destroyable chemical coating or external stimulation by electrowetting and ultra-violet (UV) illumination.

  17. Facile synthesis of ZnO nanorod arrays and hierarchical nanostructures for photocatalysis and gas sensor applications.

    PubMed

    Ma, Shuaishuai; Li, Rong; Lv, Changpeng; Xu, Wei; Gou, Xinglong

    2011-08-30

    A facile one-step hydrothermal route was demonstrated to grow ZnO nanorod arrays and hierarchical nanostructures on arbitrary substrates without any catalysts and seeds coated before the reaction, which are prerequisite in the current two-step protocol. Meanwhile, ZnO nanoflowers composed of nanorods were obtained at the bottom of the autoclaves in the absence of substrates. An in situ spontaneous-seeds-assisted growth mechanism was tentatively proposed on the basis of the experimental data to explain the growth process of ZnO nanostructures. Moreover, the obtained ZnO nanorod arrays exhibited superior photocatalytic activity for decomposing methyl orange, and the nanoflowers showed better gas sensing performance towards some flammable gases and corrosive vapors with high sensitivity, rapid response-recovery characteristics, good selectivity and long-term stability. PMID:21684076

  18. Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation.

    PubMed

    Wei, Guoke; Wang, Jinliang; Chen, Yu

    2015-01-01

    The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) from two-dimensional (2D) hexagonal silver nanorod (AgNR) arrays were investigated in terms of electromagnetic (EM) mechanism by using the discrete dipole approximation (DDA) method. The dependence of EF on several parameters, i.e., structure, length, excitation wavelength, incident angle and polarization, and gap size has been investigated. "Hotspots" were found distributed in the gaps between adjacent nanorods. Simulations of AgNR arrays of different lengths revealed that increasing the rod length from 374 to 937 nm (aspect ratio from 2.0 to 5.0) generated more "hotspots" but not necessarily increased EF under both 514 and 532 nm excitation. A narrow lateral gap (in the incident plane) was found to result in strong EF, while the dependence of EF on the diagonal gap (out of the incident plane) showed an oscillating behavior. The EF of the array was highly dependent on the angle and polarization of the incident light. The structure of AgNR and the excitation wavelength were also found to affect the EF. The EF of random arrays was stronger than that of an ordered one with the same average gap of 21 nm, which could be explained by the exponential dependence of EF on the lateral gap size. Our results also suggested that absorption rather than extinction or scattering could be a good indicator of EM enhancement. It is expected that the understanding of the dependence of local field enhancement on the structure of the nanoarrays and incident excitations will shine light on the optimal design of efficient SERS substrates and improved performance. PMID:25821708

  19. Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation

    PubMed Central

    Wei, Guoke; Wang, Jinliang

    2015-01-01

    Summary The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) from two-dimensional (2D) hexagonal silver nanorod (AgNR) arrays were investigated in terms of electromagnetic (EM) mechanism by using the discrete dipole approximation (DDA) method. The dependence of EF on several parameters, i.e., structure, length, excitation wavelength, incident angle and polarization, and gap size has been investigated. “Hotspots” were found distributed in the gaps between adjacent nanorods. Simulations of AgNR arrays of different lengths revealed that increasing the rod length from 374 to 937 nm (aspect ratio from 2.0 to 5.0) generated more “hotspots” but not necessarily increased EF under both 514 and 532 nm excitation. A narrow lateral gap (in the incident plane) was found to result in strong EF, while the dependence of EF on the diagonal gap (out of the incident plane) showed an oscillating behavior. The EF of the array was highly dependent on the angle and polarization of the incident light. The structure of AgNR and the excitation wavelength were also found to affect the EF. The EF of random arrays was stronger than that of an ordered one with the same average gap of 21 nm, which could be explained by the exponential dependence of EF on the lateral gap size. Our results also suggested that absorption rather than extinction or scattering could be a good indicator of EM enhancement. It is expected that the understanding of the dependence of local field enhancement on the structure of the nanoarrays and incident excitations will shine light on the optimal design of efficient SERS substrates and improved performance. PMID:25821708

  20. Fabrication and properties of a branched (NH₄)xWO₃ nanowire array film and a porous WO3 nanorod array film.

    PubMed

    Liu, Ya; Zhao, Liang; Su, Jinzhan; Li, Mingtao; Guo, Liejin

    2015-02-18

    We describe the successful fabrication of a three-dimensional branched (NH4)xWO3 nanowire array film on fluorine-doped tin oxide coated glass by a facile one-step hydrothermal method. The porous WO3 nanorod array film formed after heat treatment and recrystallization. Specifically, the branched (NH4)xWO3 nanowire array film has very thin nanowires that were about 10 nm in diameter. The results of an optical and photoelectrochemical test show that the branched (NH4)xWO3 nanowire array film could be used as a near-infrared shielder, while the porous WO3 nanorod array film can be used as a photoanode for water splitting. Moreover, the morphology, structure, and composition of the as-prepared films are revealed, and the related changes caused by heat treatment are discussed in detail. PMID:25623076

  1. Thickness-controlled synthesis of vertically aligned c-axis oriented ZnO nanorod arrays: Effect of growth time via novel dual sonication sol-gel process

    NASA Astrophysics Data System (ADS)

    Firdaus Malek, Mohd; Hafiz Mamat, Mohamad; Soga, Tetsuo; Rahman, Saadah Abdul; Abu Bakar, Suriani; Syakirin Ismail, Ahmad; Mohamed, Ruziana; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop Mahmood, Mohamad

    2016-01-01

    Zinc-oxide (ZnO) nanorod arrays were successfully prepared by using dual sonication sol-gel process. Field emission scanning electron microscopy revealed that the nanorods exhibited a hexagonal structure with a flat-end facet. The nanorods displayed similar surface morphologies and grew uniformly on the seed layer substrate, with the average diameter slightly increasing to the range of 65 to 80 nm after being immersed for varying growth times. Interestingly, thickness measurements indicated that the thicknesses of the samples increased as the growth time was extended. In addition, the X-ray diffraction spectra indicated that the prepared ZnO nanorods with a hexagonal wurtzite structure grew preferentially along the c-axis. Therefore, we can conclude that the diameter, length, and orientation of the ZnO nanorod arrays along the c-axis are controllable by adjusting the growth time, motivating us to further explore the growth mechanisms of ZnO nanorods.

  2. Fe2O3–TiO2 core–shell nanorod arrays for visible light photocatalytic applications

    DOE PAGESBeta

    Yao, Kun; Basnet, Pradip; Sessions, Henry; Larsen, George K.; Murph, Simona E. Hunyadi; Zhao, Yiping

    2015-11-11

    By using the glancing angle deposition technique and post-deposition annealing, Fe2O3–TiO2 core-shell nanorod arrays with specific crystalline states can be designed and fabricated. The Fe2O3–TiO2 core-shell samples annealed at temperatures greater than 450°C formed α-Fe2O3 and anatase TiO2, and showed higher catalytic efficiency for the degradation of methylene blue (MB) under visible light illumination when compared with pure anatase TiO2 or α-Fe2O3 nanorod arrays. Solar conversion of carbon dioxide and water vapor in the presence of Fe2O3–TiO2 core-shell nanorod arrays was also investigated. Carbon monoxide, hydrogen, methane, and methanol along with other hydrocarbons were produced after only several hours’ exposuremore » under ambient sunlight. It was determined that the core-shell structure showed greater efficiency for solar CO2 conversion than the pure TiO2 nanorod arrays.« less

  3. A highly efficient fluorescent sensor of explosive peroxide vapor via ZnO nanorod array catalyzed deboronation of pyrenyl borate.

    PubMed

    He, Chao; Zhu, Defeng; He, Qingguo; Shi, Liqi; Fu, Yanyan; Wen, Dan; Cao, Huimin; Cheng, Jiangong

    2012-06-11

    A new strategy capable of detecting explosive peroxide vapor via deboronation reaction induced fluorescence quenching has been developed. Using ordered assembly arrays of ZnO nanorods as catalyzing substrates, the deboronation reaction was 42 times faster than that on quartz substrates, which resulted in a very fast response and high sensitivity. PMID:22552712

  4. Regularly-patterned nanorod light-emitting diode arrays grown with metalorganic vapor-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Tu, Charng-Gan; Su, Chia-Ying; Liao, Che-Hao; Hsieh, Chieh; Yao, Yu-Feng; Chen, Hao-Tsung; Lin, Chun-Han; Chen, Horng-Shyang; Kiang, Yean-Woei; Yang, C. C.

    2015-07-01

    The growth and fabrication of GaN nanorod (NR) light-emitting diode (LED) arrays have attracted much attention because of their advantages of higher crystal quality, larger sidewall emission area, and non-polar or semi-polar quantum well (QW) formation. In this paper, we review the development of regularly-patterned GaN NR LED arrays grown with metalorganic vapor-phase epitaxy. Such an array device is expected to be useful for practical lighting application. A regularly-patterned NR array is grown on a patterned template with either continuous or pulsed growth mode. Usually, with the pulsed growth mode, by switching group-III and V sources on and off alternatively, the NR geometry can be more uniform over an array. InGaN/GaN QWs can be deposited on the c-plane top face, m-plane sidewalls, and { 1 1 bar 0 1 } -plane slant facets on a c-axis-oriented NR with the highest (lowest) growth rate in the c-plane ({ 1 1 bar 0 1 } -plane). After the overgrowth of p-GaN on an NR with n-GaN core and QW deposition, an NR LED array can be implemented by covering the NRs with a transparent conductor. It has been demonstrated that the optical and electrical performances of an NR LED array can be comparable to those of a planar LED. Further developments in NR LED growth and process techniques can lead to an outperforming LED device with the NR structure.

  5. Synthesis and Characterization of Nanoporous Alumina Films and their Application to Nanorod Array Fabrication

    NASA Astrophysics Data System (ADS)

    Abolhassani Monfared, Negar

    The purpose of this study is to synthesize and characterize the nanoporous structures that can be obtained by the anodization of thin film aluminum sputter deposited on a silicon wafer substrate. This study also investigated the application of nanoporous alumina to fabricate nanorod arrays by using preceramic polymers. Although there are many studies on the effect of anodizing conditions on anodized alumina, there are a few studies on anodizing of thin film aluminum. Anodized thin film of aluminum supported on silicon could have several applications that involve integrating the nanoporous structures into chemical and biological sensors and as templates for creating hierarchically complex nanostructures that are integrated with microelectronic circuits. In this study the different attributes of anodizing parameters in the synthesis of nanoporous structures on thin film aluminum compared to the results of studies on aluminum bulk is investigated. These differences can be due to attributes of the material, the resistance of the substrate and the reactions of substrate during anodizing. In this study the effects of different anodizing parameters and the contribution of each parameter were investigated using statistical approaches for quantification of pore sizes, their distributions and pore densities. This approach has never been previously used for studying the aluminum anodization. Until now, studies have always been based on average of the structure parameters with the hypothesis of homogeneity and uniformity of the structure which is not the case for anodization of thin film aluminum. To investigate the relative effect of each parameter, the Taguchi method and signal-to-noise calculation were applied. A new fabrication method for making nanorod arrays was introduced. In this method, nanoporous alumina was used as a casting mold for being filled by a preceramic polymer. KDT Ceraset polysilazane 20 (PSZ) and KDT Ceraset polyureasilazane (PUSZ) were two preceramic

  6. Ti nanorod arrays with a medium density significantly promote osteogenesis and osteointegration

    PubMed Central

    Ning, Chengyun; Wang, Shuangying; Zhu, Ye; Zhong, Meiling; Lin, Xi; Zhang, Yu; Tan, Guoxin; Li, Mei; Yin, Zhaoyi; Yu, Peng; Wang, Xiaolan; Li, Ying; He, Tianrui; Chen, Wei; Wang, Yingjun; Mao, Chuanbin

    2016-01-01

    Ti implants are good candidates in bone repair. However, how to promote bone formation on their surface and their consequent perfect integration with the surrounding tissue is still a challenge. To overcome such challenge, we propose to form Ti nanorods on their surface to promote the new bone formation around the implants. Here Ti nanorod arrays (TNrs) with different densities were produced on pure Ti surfaces using an anodizing method. The influence of TNr density on the protein adsorption as well as on the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 pre-osteoblastic cells were assessed. The TNrs were also implanted into the bone defects in rabbits to test their application in promoting bone formation and osteointegration at the implant-bone interface. TNrs with the medium density were found to show the best capability in promoting the protein adsorption from surrounding medium, which in turn efficiently enhanced osteogenic differentiation in vitro and osteointegration in vivo. Our work suggests that growing TNrs with a medium density on the surface of traditional Ti implants is an efficient and facile method for promoting bone formation and osteointegration in bone repair. PMID:26743328

  7. Perovskite Nanoparticle-Sensitized Ga2O3 Nanorod Arrays for CO Detection at High Temperature.

    PubMed

    Lin, Hui-Jan; Baltrus, John P; Gao, Haiyong; Ding, Yong; Nam, Chang-Yong; Ohodnicki, Paul; Gao, Pu-Xian

    2016-04-13

    Noble metal nanoparticles are extensively used for sensitizing metal oxide chemical sensors through the catalytic spillover mechanism. However, due to earth-scarcity and high cost of noble metals, finding replacements presents a great economic benefit. Besides, high temperature and harsh environment sensor applications demand material stability under conditions approaching thermal and chemical stability limits of noble metals. In this study, we employed thermally stable perovskite-type La0.8Sr0.2FeO3 (LSFO) nanoparticle surface decoration on Ga2O3 nanorod array gas sensors and discovered an order of magnitude enhanced sensitivity to carbon monoxide at 500 °C. The LSFO nanoparticle catalysts was of comparable performance to that achieved by Pt nanoparticles, with a much lower weight loading than Pt. Detailed electron microscopy and X-ray photoelectron spectroscopy studies suggested the LSFO nanoparticle sensitization effect is attributed to a spillover-like effect associated with the gas-LSFO-Ga2O3 triple-interfaces that spread the negatively charged surface oxygen ions from LSFO nanoparticles surfaces over to β-Ga2O3 nanorod surfaces with faster surface CO oxidation reactions. PMID:27043430

  8. Ti nanorod arrays with a medium density significantly promote osteogenesis and osteointegration

    NASA Astrophysics Data System (ADS)

    Ning, Chengyun; Wang, Shuangying; Zhu, Ye; Zhong, Meiling; Lin, Xi; Zhang, Yu; Tan, Guoxin; Li, Mei; Yin, Zhaoyi; Yu, Peng; Wang, Xiaolan; Li, Ying; He, Tianrui; Chen, Wei; Wang, Yingjun; Mao, Chuanbin

    2016-01-01

    Ti implants are good candidates in bone repair. However, how to promote bone formation on their surface and their consequent perfect integration with the surrounding tissue is still a challenge. To overcome such challenge, we propose to form Ti nanorods on their surface to promote the new bone formation around the implants. Here Ti nanorod arrays (TNrs) with different densities were produced on pure Ti surfaces using an anodizing method. The influence of TNr density on the protein adsorption as well as on the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 pre-osteoblastic cells were assessed. The TNrs were also implanted into the bone defects in rabbits to test their application in promoting bone formation and osteointegration at the implant-bone interface. TNrs with the medium density were found to show the best capability in promoting the protein adsorption from surrounding medium, which in turn efficiently enhanced osteogenic differentiation in vitro and osteointegration in vivo. Our work suggests that growing TNrs with a medium density on the surface of traditional Ti implants is an efficient and facile method for promoting bone formation and osteointegration in bone repair.

  9. Fabrication of Vertically Aligned Carbon Nanotube or Zinc Oxide Nanorod Arrays for Optical Diffraction Gratings.

    PubMed

    Kim, Jeong; Kim, Sun Il; Cho, Seong-Ho; Hwang, Sungwoo; Lee, Young Hee; Hur, Jaehyun

    2015-11-01

    We report on new fabrication methods for a transparent, hierarchical, and patterned electrode comprised of either carbon nanotubes or zinc oxide nanorods. Vertically aligned carbon nanotubes or zinc oxide nanorod arrays were fabricated by either chemical vapor deposition or hydrothermal growth, in combination with photolithography. A transparent conductive graphene layer or zinc oxide seed layer was employed as the transparent electrode. On the patterned surface defined using photoresist, the vertically grown carbon nanotubes or zinc oxides could produce a concentrated electric field under applied DC voltage. This periodic electric field was used to align liquid crystal molecules in localized areas within the optical cell, effectively modulating the refractive index. Depending on the material and morphology of these patterned electrodes, the diffraction efficiency presented different behavior. From this study, we established the relationship between the hierarchical structure of the different electrodes and their efficiency for modulating the refractive index. We believe that this study will pave a new path for future optoelectronic applications. PMID:26726580

  10. FAST TRACK COMMUNICATION: (La,Sr)CoO3/ZnO nanofilm-nanorod diode arrays for photo-responsive moisture and humidity detection

    NASA Astrophysics Data System (ADS)

    Gao, Haiyong; Cai, Wenjie; Shimpi, Paresh; Lin, Hui-Jan; Gao, Pu-Xian

    2010-07-01

    Large scale (La,Sr)CoO3 (LSCO)/ZnO nanofilm-nanorod diode arrays have been successfully fabricated using a combination of hydrothermal synthesis and colloidal deposition. With well-controlled dimensionality, crystallinity, crystal structures and device structures, LSCO/ZnO nanofilm-nanorod diode arrays display an excellent rectifying current-voltage (I-V) characteristic under ±1 V bias with negligible leakage current upon reverse bias. These nanostructured diode arrays have been found to be sensitive to UV illumination and different relative humidities at room temperature upon forward bias. A negative photoconductivity response is revealed upon UV illumination on the diode arrays as a result of the desorption process of nanofilm-nanorod surface moisture. The forward current of LSCO/ZnO nanofilm-nanorod diodes increases significantly with increasing relative humidity. These unique nanostructured diode arrays could be useful as photo-responsive moisture and humidity detectors.

  11. Quantum Symmetry Breaking of Exciton/Polaritons in a Metal-Nanorod Plasmonic Array.

    PubMed

    Zaster, Svitlana; Bittner, Eric R; Piryatinski, Andrei

    2016-05-19

    We study the collective, superradiant behavior in the system of emitter-dressed Ag nanorods. Starting from the Drude model for the plasmon oscillations, we arrive at a semiempirical Hamiltonian describing the coupling between quantized surface plasmon modes and the quantum emitters that can be controlled by manipulating their geometry, spacing, and orientation. Further, identifying the lowest polariton mode as SP-states dressed by excitons in the vicinity of k = 0, we examine conditions allowing for the polariton quantum-phase transition. Though the system is formally a 1D array, we show that the polariton states of interest can undergo a quantum-phase transition to form a Bose condensate at finite temperatures for physically accessible parameter ranges. PMID:26905014

  12. Enhanced polarization of (11–22) semi-polar InGaN nanorod array structure

    SciTech Connect

    Athanasiou, M.; Smith, R. M.; Hou, Y.; Zhang, Y.; Gong, Y.; Wang, T.

    2015-10-05

    By means of a cost effective nanosphere lithography technique, an InGaN/GaN multiple quantum well structure grown on (11–22) semipolar GaN has been fabricated into two dimensional nanorod arrays which form a photonic crystal (PhC) structure. Such a PhC structure demonstrates not only significantly increased emission intensity, but also an enhanced polarization ratio of the emission. This is due to an effective inhibition of the emission in slab modes and then redistribution to the vertical direction, thus minimizing the light scattering processes that lead to randomizing of the optical polarization. The PhC structure is designed based on a standard finite-difference-time-domain simulation, and then optically confirmed by detailed time-resolved photoluminescence measurements. The results presented pave the way for the fabrication of semipolar InGaN/GaN based emitters with both high efficiency and highly polarized emission.

  13. Strong light coupling effect for a glancing-deposited silver nanorod array in the Kretschmann configuration

    PubMed Central

    2014-01-01

    In this work, three slanted silver nanorod arrays (NRAs) with different thicknesses are fabricated using the glancing angle deposition method. Each silver NRA in the Kretschmann configuration is arranged to form a prism/NRA/air system. Attenuated total reflection occurs over the visible wavelengths and wide incident angles of both s- and p-polarization states. The extinctance is inversely proportional to the thickness of the Ag NRA. The thinnest NRA, with a thickness of 169 nm, exhibits strong extinctance of more than 80% over the visible wavelengths. The associated forward scatterings from the three NRAs are measured and compared under illumination with a laser beam with a wavelength of 632.8 nm. PMID:25352769

  14. Immobilization of a Molecular Ruthenium Catalyst on Hematite Nanorod Arrays for Water Oxidation with Stable Photocurrent.

    PubMed

    Fan, Ke; Li, Fusheng; Wang, Lei; Daniel, Quentin; Chen, Hong; Gabrielsson, Erik; Sun, Junliang; Sun, Licheng

    2015-10-12

    Photoelectrochemical (PEC) cells for light-driven water splitting are prepared using hematite nanorod arrays on conductive glass as the photoanode. These devices improve the photocurrent of the hematite-based photoanode for water splitting, owing to fewer surface traps and decreased electron recombination resulting from the one-dimensional structure. By employing a molecular ruthenium co-catalyst, which contains a strong 2,6-pyridine-dicarboxylic acid anchoring group at the hematite photoanode, the photocurrent of the PEC cell is enhanced with high stability for over 10 000 s in a 1 m KOH solution. This approach can pave a route for combining one-dimensional nanomaterials and molecular catalysts to split water with high efficiency and stability. PMID:26315677

  15. Electropolymerization of Uniform Polyaniline Nanorod Arrays on Conducting Oxides as Counter Electrodes in Dye-Sensitized Solar Cells.

    PubMed

    He, Ziming; Liu, Jing; Khoo, Si Yun; Tan, Timothy Thatt Yang

    2016-01-01

    Conventional techniques for the synthesis of oriented polyaniline (PANI) nanostructures are often complex or time consuming. Through an innovative reduced graphene oxide (rGO) modified FTO and a low-potential electropolymerization strategy, the rapid and template-free growth of a highly ordered PANI nanorod array on the FTO substrate is realized. The highly ordered nanostructure of the PANI array leads to a high electrocatalytic activity and chemical stability. The importance of the polymerization potential and rGO surface modification to achieve this nanostructure is revealed. Compared to platinum, the PANI nanorod array exhibits an enhanced performance and stability as counter electrodes in dye-sensitized solar cells, with a 17.6 % enhancement in power conversion efficiency. PMID:26732134

  16. Metal enhanced fluorescence improved protein and DNA detection by zigzag Ag nanorod arrays.

    PubMed

    Ji, Xiaofan; Xiao, Chenyu; Lau, Wai-Fung; Li, Jianping; Fu, Junxue

    2016-08-15

    As metal nano-arrays show great potential on metal enhanced fluorescence (MEF) than random nanostructures, MEF of Ag zigzag nanorod (ZNR) arrays made by oblique angle deposition has been studied for biomolecule-protein interaction and DNA hybridization. By changing the folding number and the deposition substrate temperature, a 14-fold enhancement factor (EF) is obtained for biotin-neutravidin detection. The optimal folding number is decided as Z=7, owing to the high scattering intensity of Ag ZNRs. The substrate temperature T=25°C and 0°C slightly alters the morphology of Ag ZNRs but has no big difference in EF. Further, Ag ZNRs deposited on a layer of Ag film have been introduced to the DNA hybridization and a significant signal enhancement has been observed through the fluorescence microscope. Through a detailed quantitative EF analysis, which excludes the enhancing effect from the increased surface area of ZNRs and only considers the contribution of MEF, an EF of 28 is achieved for the hybridization of two single-stranded oligonucleotides with 33 bases. Furthermore, a limit of detection is determined as 0.01pM. We believe that the Ag ZNR arrays can serve as a universal and sensitive bio-detection platform. PMID:27088369

  17. Photoelectrocatalytic activity of a hydrothermally grown branched Zno nanorod-array electrode for paracetamol degradation.

    PubMed

    Lin, Chin Jung; Liao, Shu-Jun; Kao, Li-Cheng; Liou, Sofia Ya Hsuan

    2015-06-30

    Hierarchical branched ZnO nanorod (B-ZnR) arrays as an electrode for efficient photoelectrocatalytic degradation of paracetamol were grown on fluorine-doped tin oxide substrates using a solution route. The morphologic and structural studies show the ZnO trunks are single-crystalline hexagonal wurtzite ZnO with a [0001] growth direction and are densely covered by c-axis-oriented ZnO branches. The obvious enhancement in photocurrent response of the B-ZnR electrode was obtained than that in the ZnO nanoparticle (ZnO NP) electrode. For the photoelectrocatalytic degradation of paracetamol in 20 h, the conversion fraction of the drug increased from 32% over ZnO NP electrode to 62% over B-ZnR arrays with about 3-fold increase in initial reaction rate. The light intensity-dependent photoelectrocatalytic experiment indicated that the superior performance over the B-ZnR electrode was mainly ascribed to the increased specific surface area without significantly sacrificing the charge transport and pollutant diffusion efficiencies. Two aromatic intermediate compounds were observed and eventually converted into harmless carboxylic acids and ammonia. Hierarchical tree-like ZnO arrays can be considered effective alternatives to improve photoelectro degradation rates without the need for expensive additives. PMID:25748997

  18. Plasmon-Driven Dynamic Response of a Hierarchically Structural Silver-Decorated Nanorod Array for Sub-10 nm Nanogaps.

    PubMed

    Wang, Yi; Wang, Hailong; Wang, Yuyang; Shen, Yanting; Xu, Shuping; Xu, Weiqing

    2016-06-22

    Plasmonic nanogaps serve as a useful configuration for light concentration and local field amplification owing to the extreme localization of surface plasmons. Here, a smart plasmonic nanogap device is fabricated by the dynamic response of an Ag decorated hierarchically structural vertical polymer nanorod array under the light irradiation. Seven nanorods in one unit bend because of plasmonic heating effect and they are centrally collected due to the attraction of the plasmon-induced polaritons, leading to the significantly enhanced local electromagnetic field at the sub-10 nm gaps among the constricted nanorod tops. Compared with tuning capillarity in microscale by wetting and drying, using light as external stimuli is much easier and more tunable in nanoscale. This plasmonic nanogap device is used for a surface-enhanced Raman scattering (SERS) substrate. Its hydrophobic surface with a contact angle of 142 degree can make the probed aqueous solution only access to the Ag tips of nanorods. Thus, the analytes can be driven to the "hot spot" regions where located at the tops of nanorods during the solvent evaporation process, which is beneficial to SERS detection. Discovery of this smart plasmon-driven process broadens the scope for further functionality of both the dynamic nanostructure design and the smart plasmonic devices in the communities of chemistry, biomedicine, and microfluidic engineering. PMID:27250862

  19. Template based precursor route for the synthesis of CuInSe2 nanorod arrays for potential solar cell applications

    PubMed Central

    Pashchanka, Mikhail; Balog, Ildiko; Hoffmann, Rudolf C

    2013-01-01

    Summary Polycrystalline CuInSe2 (CISe) nanorods are promising for the fabrication of highly efficient active layers in solar cells. In this work we report on a nanocasting approach, which uses track-etched polycarbonate films as hard templates for obtaining three-dimensionally (3D) arranged CISe nanorod arrays. Copper and indium ketoacidoximato complexes and selenourea were employed as molecular precursors. Arrays of parallel isolated cylindrical pores of 100 nm nominal diameter and 5 μm length were used for the infiltration of the precursor solution under inert atmosphere, followed by drying, thermal conversion into a preceramic ‘green body’, a subsequent dissolution of the template, and a final thermal treatment at 450 °C. The nanorods that where synthesised in this way have dimensions equal to the pore sizes of the template. Investigation of the CuInSe2 nanorod samples by spectroscopic and diffraction methods confirmed a high purity and crystallinity, and a stoichiometric composition of the CISe ternary semiconductor compound. PMID:24367756

  20. Vertically aligned ZnO nanorod core-polypyrrole conducting polymer sheath and nanotube arrays for electrochemical supercapacitor energy storage

    PubMed Central

    2014-01-01

    Nanocomposite electrodes having three-dimensional (3-D) nanoscale architecture comprising of vertically aligned ZnO nanorod array core-polypyrrole (PPy) conducting polymer sheath and the vertical PPy nanotube arrays have been investigated for supercapacitor energy storage. The electrodes in the ZnO nanorod core-PPy sheath structure are formed by preferential nucleation and deposition of PPy layer over hydrothermally synthesized vertical ZnO nanorod array by controlled pulsed current electropolymerization of pyrrole monomer under surfactant action. The vertical PPy nanotube arrays of different tube diameter are created by selective etching of the ZnO nanorod core in ammonia solution for different periods. Cyclic voltammetry studies show high areal-specific capacitance approximately 240 mF.cm-2 for open pore and approximately 180 mF.cm-2 for narrow 30-to-36-nm diameter PPy nanotube arrays attributed to intensive faradic processes arising from enhanced access of electrolyte ions through nanotube interior and exterior. Impedance spectroscopy studies show that capacitive response extends over larger frequency domain in electrodes with PPy nanotube structure. Simulation of Nyquist plots by electrical equivalent circuit modeling establishes that 3-D nanostructure is better represented by constant phase element which accounts for the inhomogeneous electrochemical redox processes. Charge-discharge studies at different current densities establish that kinetics of the redox process in PPy nanotube electrode is due to the limitation on electron transport rather than the diffusive process of electrolyte ions. The PPy nanotube electrodes show deep discharge capability with high coulomb efficiency and long-term charge-discharge cyclic studies show nondegrading performance of the specific areal capacitance tested for 5,000 cycles. PMID:25246867

  1. Island nucleation, optical and ferromagnetic properties of vertically aligned secondary growth ZnO : Cu nanorod arrays

    NASA Astrophysics Data System (ADS)

    Huang, Jun; Zhu, Liping; Hu, Liang; Liu, Shijiang; Zhang, Jie; Zhang, Honghai; Yang, Xiaopeng; Sun, Luwei; Li, Dehui; Ye, Zhizhen

    2012-02-01

    The paper reports an island nucleation and secondary growth of aligned ZnO : Cu nanorod arrays via thermal vapor phase transport. Results analysis indicates that the secondary segment is epitaxially grown on the ZnO : Cu nanorods with the radius strongly dependent on temperature and the concentration of zinc vapor. The modified characteristic radius (Rc) model is used to explain the nucleation and secondary growth process. Temperature-dependent photoluminescence spectra indicate that the band gap emission of the secondary growth nanorods is greatly restrained. A controversial 3.31 eV emission (A line) and two different donor-acceptor pair (DAP) recombinations at 3.24 eV and 2.48 eV are observed at 13 K. The A line shows a different behavior from the two DAP emissions during the heat-up process. Intrinsic room temperature ferromagnetism (RTFM) is observed in the secondary growth ZnO : Cu nanorods and it can be explained by oxygen vacancy and copper defects related to bound magnetic polar (BMP) or double exchange mechanism.The paper reports an island nucleation and secondary growth of aligned ZnO : Cu nanorod arrays via thermal vapor phase transport. Results analysis indicates that the secondary segment is epitaxially grown on the ZnO : Cu nanorods with the radius strongly dependent on temperature and the concentration of zinc vapor. The modified characteristic radius (Rc) model is used to explain the nucleation and secondary growth process. Temperature-dependent photoluminescence spectra indicate that the band gap emission of the secondary growth nanorods is greatly restrained. A controversial 3.31 eV emission (A line) and two different donor-acceptor pair (DAP) recombinations at 3.24 eV and 2.48 eV are observed at 13 K. The A line shows a different behavior from the two DAP emissions during the heat-up process. Intrinsic room temperature ferromagnetism (RTFM) is observed in the secondary growth ZnO : Cu nanorods and it can be explained by oxygen vacancy and copper

  2. Low temperature grown ZnO@TiO{sub 2} core shell nanorod arrays for dye sensitized solar cell application

    SciTech Connect

    Goh, Gregory Kia Liang; Le, Hong Quang; Huang, Tang Jiao; Hui, Benjamin Tan Tiong

    2014-06-01

    High aspect ratio ZnO nanorod arrays were synthesized on fluorine-doped tin oxide glasses via a low temperature solution method. By adjusting the growth condition and adding polyethylenimine, ZnO nanorod arrays with tunable length were successfully achieved. The ZnO@TiO{sub 2} core shells structures were realized by a fast growth method of immersion into a (NH{sub 4}){sub 2}·TiF{sub 6} solution. Transmission electron microscopy, X-ray Diffraction and energy dispersive X-ray measurements all confirmed the existence of a titania shell uniformly covering the ZnO nanorod's surface. Results of solar cell testing showed that addition of a TiO{sub 2} shell to the ZnO nanorod significantly increased short circuit current (from 4.2 to 5.2 mA/cm{sup 2}), open circuit voltage (from 0.6 V to 0.8 V) and fill factor (from 42.8% to 73.02%). The overall cell efficiency jumped from 1.1% for bare ZnO nanorod to 3.03% for a ZnO@TiO{sub 2} core shell structured solar cell with a 18–22 nm shell thickness, a nearly threefold increase. - Graphical abstract: The synthesis process of coating TiO{sub 2} shell onto ZnO nanorod core is shown schematically. A thin, uniform, and conformal shell had been grown on the surface of the ZnO core after immersing in the (NH{sub 4}){sub 2}·TiF{sub 6} solution for 5–15 min. - Highlights: • ZnO@TiO{sub 2} core shell nanorod has been grown on FTO substrate using low temperature solution method. • TEM, XRD, EDX results confirmed the existing of titana shell, uniformly covered rod's surface. • TiO{sub 2} shell suppressed recombination, demonstrated significant enhancement in cell's efficiency. • Core shell DSSC's efficiency achieved as high as 3.03%, 3 times higher than that of ZnO nanorods.

  3. Tragacanth gum biopolymer as reducing and stabilizing agent in biosonosynthesis of urchin-like ZnO nanorod arrays: A low cytotoxic photocatalyst with antibacterial and antifungal properties.

    PubMed

    Ghayempour, Soraya; Montazer, Majid; Mahmoudi Rad, Mahnaz

    2016-01-20

    Tragacanth, a natural gum, has been used for centuries as emulsifier, thickener, stabilizer and binder in various fields such as food, medical and cosmetic industries. In this study, Tragacanth gum was used as a clean and natural reducing and stabilizing agent for preparation of urchin-like ZnO nanorod arrays at low-temperature using ultrasonic irradiation. The morphology and structure of urchin-like ZnO nanorod arrays was investigated by XRD, FESEM images, EDX, UV-vis and FT-IR spectroscopy. The hexagonal zinc oxide nanorods were synthesized with the average diameter of 55-80 nm and length of 240 nm. The peak appeared in 447 cm(-1) in FTIR spectra and the peak around 362.3 nm in UV-vis spectra of ZnO nanorods confirmed the successful synthesis of ZnO nanorods. The urchin-like ZnO nanorod arrays indicated a good photocatalytic activity through degradation of methylene blue with 92.2% efficiency and rate constant of 0.0027 min(-1) at 120 min. Finally, the synthesized urchin-like ZnO nanorod arrays indicated 100% antibacterial activity against S. aureus and E. coli and 93% antifungal activity against C. albicans with a low cytotoxicity. PMID:26572351

  4. Plasmon enhanced fluorescence studies from aligned gold nanorod arrays modified with SiO2 spacer layers

    NASA Astrophysics Data System (ADS)

    Damm, Signe; Fedele, Stefano; Murphy, Antony; Holsgrove, Kristina; Arredondo, Miryam; Pollard, Robert; Barry, James N.; Dowling, Denis P.; Rice, James H.

    2015-05-01

    Here, we demonstrate that quasi self-standing Au nanorod arrays prepared with plasma polymerisation deposited SiO2 dielectric spacers support surface enhanced fluorescence (SEF) while maintaining high signal reproducibility. We show that it is possible to find a balance between enhanced radiative and non-radiative decay rates at which the fluorescent intensity is maximized. The SEF signal optimised with a 30 nm spacer layer thickness showed a 3.5-fold enhancement with a signal variance of <15% thereby keeping the integrity of the nanorod array. We also demonstrate the decreased importance of obtaining resonance conditions when localized surface plasmon resonance is positioned within the spectral region of Au interband transitions. Procedures for further increasing the SEF enhancement factor are also discussed.

  5. Plasmon-enhanced Electrically Light-emitting from ZnO Nanorod Arrays/p-GaN Heterostructure Devices

    PubMed Central

    Lu, Junfeng; Shi, Zengliang; Wang, Yueyue; Lin, Yi; Zhu, Qiuxiang; Tian, Zhengshan; Dai, Jun; Wang, Shufeng; Xu, Chunxiang

    2016-01-01

    Effective and bright light-emitting-diodes (LEDs) have attracted broad interests in fundamental research and industrial application, especially on short wavelength LEDs. In this paper, a well aligned ZnO nanorod arrays grown on the p-GaN substrate to form a heterostructured light-emitting diode and Al nanoparticles (NPs) were decorated to improve the electroluminescence performance. More than 30-folds enhancement of the electroluminescence intensity was obtained compared with the device without Al NPs decoration. The investigation on the stable and transient photoluminescence spectraof the ZnO nanorod arrays before and after Al NPs decoration demonstrated that the metal surface plasmon resonance coupling with excitons of ZnO leads to the enhancement of the internal quantum efficiency (IQE). Our results provide aneffective approach to design novel optoelectronic devices such as light-emitting diodes and plasmonic nanolasers. PMID:27181337

  6. Morphological and SERS Properties of Silver Nanorod Array Films Fabricated by Oblique Thermal Evaporation at Various Substrate Temperatures.

    PubMed

    Oh, Myoung-Kyu; Shin, Yong-Seok; Lee, Chang-Lyoul; De, Ranjit; Kang, Hoonsoo; Yu, Nan Ei; Kim, Bok Hyeon; Kim, Joon Heon; Yang, Jin-Kyu

    2015-12-01

    Aligned silver nanorod (AgNR) array films were fabricated by oblique thermal evaporation. The substrate temperature during evaporation was varied from 10 to 100 °C using a home-built water cooling system. Deposition angle and substrate temperature were found to be the most important parameters for the morphology of fabricated films. Especially, it was found that there exists a critical temperature at ~90 °C for the formation of the AgNR array. The highest enhancement factor of the surface-enhanced Raman scattering (SERS), observed in the Ag films coated with benzenethiol monolayer, was ~6 × 10(7). Hot spots, excited in narrow gaps between nanorods, were attributed to the huge enhancement factor by our finite-difference time-domain (FDTD) simulation reflecting the real morphology. PMID:26061442

  7. Plasmon enhanced fluorescence studies from aligned gold nanorod arrays modified with SiO{sub 2} spacer layers

    SciTech Connect

    Damm, Signe; Fedele, Stefano; Rice, James H.; Murphy, Antony; Holsgrove, Kristina; Arredondo, Miryam; Pollard, Robert; Barry, James N.; Dowling, Denis P.

    2015-05-04

    Here, we demonstrate that quasi self-standing Au nanorod arrays prepared with plasma polymerisation deposited SiO{sub 2} dielectric spacers support surface enhanced fluorescence (SEF) while maintaining high signal reproducibility. We show that it is possible to find a balance between enhanced radiative and non-radiative decay rates at which the fluorescent intensity is maximized. The SEF signal optimised with a 30 nm spacer layer thickness showed a 3.5-fold enhancement with a signal variance of <15% thereby keeping the integrity of the nanorod array. We also demonstrate the decreased importance of obtaining resonance conditions when localized surface plasmon resonance is positioned within the spectral region of Au interband transitions. Procedures for further increasing the SEF enhancement factor are also discussed.

  8. Plasmon-enhanced Electrically Light-emitting from ZnO Nanorod Arrays/p-GaN Heterostructure Devices.

    PubMed

    Lu, Junfeng; Shi, Zengliang; Wang, Yueyue; Lin, Yi; Zhu, Qiuxiang; Tian, Zhengshan; Dai, Jun; Wang, Shufeng; Xu, Chunxiang

    2016-01-01

    Effective and bright light-emitting-diodes (LEDs) have attracted broad interests in fundamental research and industrial application, especially on short wavelength LEDs. In this paper, a well aligned ZnO nanorod arrays grown on the p-GaN substrate to form a heterostructured light-emitting diode and Al nanoparticles (NPs) were decorated to improve the electroluminescence performance. More than 30-folds enhancement of the electroluminescence intensity was obtained compared with the device without Al NPs decoration. The investigation on the stable and transient photoluminescence spectraof the ZnO nanorod arrays before and after Al NPs decoration demonstrated that the metal surface plasmon resonance coupling with excitons of ZnO leads to the enhancement of the internal quantum efficiency (IQE). Our results provide aneffective approach to design novel optoelectronic devices such as light-emitting diodes and plasmonic nanolasers. PMID:27181337

  9. Tailored-waveguide based photonic chip for manipulating an array of single neutral atoms.

    PubMed

    Ke, Min; Zhou, Feng; Li, Xiao; Wang, Jin; Zhan, Mingsheng

    2016-05-01

    We propose a tailored-waveguide based photonic chip with the functions of trapping, coherently manipulating, detecting and individually addressing an array of single neutral atoms. Such photonic chip consists of an array of independent functional units spaced by a few micrometers, each of which is comprised of one silica-on-silicon optical waveguide and one phase Fresnel microlens etched in the middle of the output interface of the optical waveguide. We fabricated a number of photonic chips with 7 functional units and measured optical characteristics of these chips. We further propose feasible schemes to realize the functions of such photonic chip. The photonic chip is stable, scalable and can be combined with other integrated devices, such as atom chips, and can be used in the future hybrid quantum system and photonic quantum devices. PMID:27137532

  10. Strong photonic crystal behavior in regular arrays of core-shell and quantum disc InGaN/GaN nanorod light-emitting diodes

    SciTech Connect

    Lewins, C. J. Le Boulbar, E. D.; Lis, S. M.; Shields, P. A.; Allsopp, D. W. E.; Edwards, P. R.; Martin, R. W.

    2014-07-28

    We show that arrays of emissive nanorod structures can exhibit strong photonic crystal behavior, via observations of the far-field luminescence from core-shell and quantum disc InGaN/GaN nanorods. The conditions needed for the formation of directional Bloch modes characteristic of strong photonic behavior are found to depend critically upon the vertical shape of the nanorod sidewalls. Index guiding by a region of lower volume-averaged refractive index near the base of the nanorods creates a quasi-suspended photonic crystal slab at the top of the nanorods which supports Bloch modes. Only diffractive behavior could be observed without this region. Slab waveguide modelling of the vertical structure shows that the behavioral regime of the emissive nanorod arrays depends strongly upon the optical coupling between the nanorod region and the planar layers below. The controlled crossover between the two regimes of photonic crystal operation enables the design of photonic nanorod structures formed on planar substrates that exploit either behavior depending on device requirements.

  11. LiMn{sub 2}O{sub 4} nanorod arrays: A potential three-dimensional cathode for lithium-ion microbatteries

    SciTech Connect

    Tang, Xiao; Lin, Binghui; Ge, Yong; Ge, Yao; Lu, Changjie; Savilov, Serguei V.; Aldoshin, Serguei M.; Xia, Hui

    2015-09-15

    Highlights: • Self-supported LiMn{sub 2}O{sub 4} nanorod arrays are prepared on the Pt substrates. • LiMn{sub 2}O{sub 4} nanorod array cathode exhibits a large areal capacity of 0.25 mAh cm{sup −2}. • LiMn{sub 2}O{sub 4} nanorod array cathode exhibits good cycle performance and rate capability. • LiMn{sub 2}O{sub 4} nanorod arrays are potential cathodes for 3D microbatteries. - Abstract: Although three-dimensional (3D) microbatteries represent great advantage compared to their two-dimensional counterparts, the fabrication of 3D cathode is still a challenge, which holds back the further development of 3D microbatteries. In this work, we present a novel approach for fabrication of LiMn{sub 2}O{sub 4} nanorod arrays as 3D cathode for microbatteries. α-MnO{sub 2} nanotube arrays are firstly grown on the Pt substrate as the template, and LiMn{sub 2}O{sub 4} nanorod arrays are then prepared by lithiation of α-MnO{sub 2} nanotube arrays in molten salt followed by 800 °C annealing in air. In the half cell test, the 3D LiMn{sub 2}O{sub 4} nanorod arrays exhibit both high gravimetric capacity (∼130 mAh g{sup −1}) and areal capacity (∼0.25 mAh cm{sup −2}), while maintaining good cycling stability and rate capability. The facile synthesis and superior electrochemical performance of the three-dimensional LiMn{sub 2}O{sub 4} cathode make it promising for application in microbatteries.

  12. Carrier concentration-dependent electron transfer in Cu2O/ZnO nanorod arrays and their photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Jiang, Tengfei; Xie, Tengfeng; Chen, Liping; Fu, Zewen; Wang, Dejun

    2013-03-01

    In this paper, we have engineered the interface electronic structure in Cu2O/ZnO nanorod arrays, via adjusting the carrier concentration of Cu2O, and applied them to photocatalysis. The photoinduced charge transfer kinetics at the interface between Cu2O and ZnO were systematically investigated. The Cu2O (pH 11.0)/ZnO nanorod arrays have the largest magnitude of interfacial electric field, and photoinduced charge carriers can be separated rapidly and efficiently, which generates the highest photocatalytic efficiency for the reduction of methylviologen. Heterojunction construction is an exciting direction to pursue for highly active photocatalysts, and also offers opportunities to investigate the relationship between the electronic structure and the photocatalytic performance.In this paper, we have engineered the interface electronic structure in Cu2O/ZnO nanorod arrays, via adjusting the carrier concentration of Cu2O, and applied them to photocatalysis. The photoinduced charge transfer kinetics at the interface between Cu2O and ZnO were systematically investigated. The Cu2O (pH 11.0)/ZnO nanorod arrays have the largest magnitude of interfacial electric field, and photoinduced charge carriers can be separated rapidly and efficiently, which generates the highest photocatalytic efficiency for the reduction of methylviologen. Heterojunction construction is an exciting direction to pursue for highly active photocatalysts, and also offers opportunities to investigate the relationship between the electronic structure and the photocatalytic performance. Electronic supplementary information (ESI) available: SEM images, XRD patterns, photocatalytic activities, Mott-Schottky plots, modulation frequency and light intensity dependent SPV measurements. See DOI: 10.1039/c3nr34219k

  13. (001)-orientation single crystalline Pb(Zr0.3Ti0.7)O3 pyroelectric nanorod array synthesized by hydrothermal reaction

    NASA Astrophysics Data System (ADS)

    Gui Wu, Chuan; Peng, Qiang Xiang; Sun, Xiang Yu; Meng, Jia; Yao, Shuai; Luo, Wen Bo; Li Zhang, Wan

    2015-04-01

    The fabrication and pyroelectric coefficient of Pb(Zr0.3Ti0.7)O3 (PZT) nanorod array on Nb:SrTiO3 (NSTO) substrates were reported. XRD and TEM revealed that PZT nanorods were (001) orientation single crystalline. Dense PZT nanorod array were synthesized on NSTO using optimal 0.8 g/L poly(vinyl alcohol) (PVA) and 3.2 g/L poly(acrylate acid) (PAA). Maximum pyroelectric coefficient, 5.8 × 10-9 C/(cm2·K), was measured for samples synthesized at 230 °C and poled under 5 V. The single crystalline PZT nanorod array material has potential application in small spatial (1-10 µm) infrared detectors, benefiting to achieve distinguished detector performances.

  14. Structure and magnetic properties of three-dimensional (La,Sr)MnO{sub 3} nanofilms on ZnO nanorod arrays

    SciTech Connect

    Gao Haiyong; Gao Puxian; Shimpi, Paresh; Guo Yanbing; Cai Wenjie; Lin Huijan; Staruch, M.; Jain, Menka

    2011-03-21

    Three-dimensional (3D) cubic perovskite (La,Sr)MnO{sub 3} (LSMO) nanofilms have been deposited on ZnO nanorod arrays with controlled dimensionality and crystallinity by radio frequency (rf) magnetron sputtering and post thermal annealing. Compared to the two-dimensional (2D) LSMO nanofilm on flat Si, the structure and magnetic properties of 3D LSMO nanofilms on ZnO nanorod arrays have a strong anisotropic morphology and thickness dependence. Ferromagnetic property has been observed in both 2D and 3D LSMO nanofilms while a ferromagnetic-superparamagnetic transition was revaled in 3D LSMO nanofilms on ZnO nanorod array with decreasing nanofilm thickness, due to a large surface dispersion effect. The LSMO/ZnO nanofilm/nanorod structures could open up new avenues for intriguing magnetic properties studies and applications of nanoscale perovskites.

  15. An approach to self-cleaning SERS sensors by arraying Au nanorods on TiO II layer

    NASA Astrophysics Data System (ADS)

    Li, Shuyi; Suzuki, Motofumi; Nakajima, Kaoru; Kimura, Kenji; Fukuoka, Takao; Mori, Yasushige

    2007-09-01

    We have demonstrated stable surface-enhanced Raman spectroscopy (SERS) on arrays of Au nanorods aligned on a photocatalytic TiO II layer. We used dynamic oblique deposition (DOD) in order to control the morphology of both the Au nanorods and the TiO II layer so that both Au and TiO II appear on the surface and play the roles of Raman enhancer and self-cleaner, respectively. TiO II template layer was formed by depositing Ti IIO 3 onto heated glass substrate in an oxygen atmosphere so that it was ready as photocatalyst when the deposition was over, without post annealing in the air. A serial bideposition technique (SBD) at a deposition angle of 85° was used to control the morphology of TiO II layer suitable for the growth of Au nanorods. Then, Au nanorods were arrayed by depositing Au with different deposition angles and thicknesses on the TiO II layer. We investigated the photocatalysis and SERS properties of the samples and found that they show both good photocatalysis and strong signals of SERS although these properties varies depend on the deposition angle and thickness of Au layer. Most importantly, we found that the SERS signals measured on our samples have shown spatially-, temporally-stable characters which have not been observed before on the Ag or Au nanorods deposited on a SiO II layer. This stability is interpreted in terms of the self-cleaning character due to the photocatalytic TiO2 template layer.

  16. Recyclable three-dimensional Ag nanoparticle-decorated TiO2 nanorod arrays for surface-enhanced Raman scattering.

    PubMed

    Fang, Hui; Zhang, Chang Xing; Liu, Luo; Zhao, Yong Mei; Xu, Hai Jun

    2015-02-15

    Multifunctional Ag nanoparticle-decorated TiO2 nanorod arrays were prepared by two simple processes. TiO2 nanorod arrays were first fabricated by the hydrothermal route and then Ag nanoparticles were decorated on the nanorods by the chemical reduction impregnation method. Three-dimensional Ag/TiO2 arrays were used as an active substrate for surface-enhanced Raman scattering (SERS). The results show that the detection limit for rhodamine 6G (R6G) was as low as 10(-7)M and the Raman enhancement factor was as large as 10(5). After calibrating the Raman peak intensities of R6G, it could be quantitatively detected. More importantly, the photocatalytic activity of TiO2 provides a self-cleaning capability to the SERS substrate, which can be recycled and used to degrade many Ag surface adsorbates such as R6G, methyl orange, Congo red, and methylene blue after exposure to visible light. The absorbed small molecules can all be rapidly and completely removed from the SERS substrate, which has been successfully reused four times without a decrease in accuracy or sensitivity. Our results reveal that the unique recyclable property not only paves a new way to solve the single-use problem of traditional SERS substrates but also provides more SERS platforms for multiple detections of other organic molecular species. PMID:25282397

  17. Photodeposition of Ag2S on TiO2 nanorod arrays for quantum dot-sensitized solar cells

    PubMed Central

    2013-01-01

    Ag2S quantum dots were deposited on the surface of TiO2 nanorod arrays by a two-step photodeposition. The prepared TiO2 nanorod arrays as well as the Ag2S deposited electrodes were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, suggesting a large coverage of Ag2S quantum dots on the ordered TiO2 nanorod arrays. UV–vis absorption spectra of Ag2S deposited electrodes show a broad absorption range of the visible light. The quantum dot-sensitized solar cells (QDSSCs) based on these electrodes were fabricated, and the photoelectrochemical properties were examined. A high photocurrent density of 10.25 mA/cm2 with a conversion efficiency of 0.98% at AM 1.5 solar light of 100 mW/cm2 was obtained with an optimal photodeposition time. The performance of the QDSSC at different incident light intensities was also investigated. The results display a better performance at a lower incident light level with a conversion efficiency of 1.25% at 47 mW/cm2. PMID:23286551

  18. Dense arrays of cobalt nanorods as rare-earth free permanent magnets

    NASA Astrophysics Data System (ADS)

    Anagnostopoulou, E.; Grindi, B.; Lacroix, L.-M.; Ott, F.; Panagiotopoulos, I.; Viau, G.

    2016-02-01

    allowed a quantitative assessment of the (BH)max values. The highest (BH)max of 165 kJ m-3 was obtained for a sample combining a high magnetic volume fraction and a very large M(H) loop squareness. This study shows that this bottom-up approach is very promising to get new hard magnetic materials that can compete in the permanent magnet panorama and fill the gap between the ferrites and the NdFeB magnets. Electronic supplementary information (ESI) available: Transmission electron microscopy images of the cobalt nanorods; thermogravimetric analysis of a dense array of cobalt nanorods; Table S1 details on the rod washing and alignment procedure. See DOI: 10.1039/c5nr07143g

  19. Sputtered highly ordered TiO2 nanorod arrays and their applications as the electrode in dye-sensitized solar cells.

    PubMed

    Meng, Lijian; Ma, Aifeng; Ying, Pinliang; Feng, Zhaochi; Li, Can

    2011-02-01

    For the first time, the TiO2 nanorod arrays have been prepared on ITO substrates at room temperature by dc reactive magnetron sputtering technique. These TiO2 nanorods have a preferred orientation along the (220) direction and are perpendicular to the ITO substrate. Both the X-ray diffraction and Raman scattering measurements show that the highly ordered TiO2 nanorod arrays have an anatase crystal structure. The diameter of the nanorod varies from 30 nm to 100 nm and the nanorod length can be varied from several hundred nanometers to several micrometers depending on the deposition time. The TiO2 nanorod arrays with about 3 micrometers length have been used as an electrode for dye-sensitized solar cell (DSSC). Short-circuit photocurrent density, open-circuit voltage, fill factor and light-to-electricity conversion efficiency at 100 mW/cm2 light intensity are estimated to be 12.76 mA/cm2, 0.65 V, 0.63 and 5.25%, respectively, for the DSSC made of the TiO2 nanorods. PMID:21456121

  20. General Route to ZnO Nanorod Arrays on Conducting Substrates via Galvanic-cell-based approach

    NASA Astrophysics Data System (ADS)

    Zheng, Zhaoke; Lim, Zhi Shiuh; Peng, Yuan; You, Lu; Chen, Lang; Wang, Junling

    2013-08-01

    Wurtzite ZnO nanorod exhibits many unique properties, which make it promising for various optoelectronic applications. To grow well-aligned ZnO nanorod arrays on various substrates, a seed layer is usually required to improve the density and vertical alignment. The reported works about seedless hydrothermal synthesis either require special substrates, or require external electrical field to enhance the ZnO nucleation. Here, we report a general method for the one-pot synthesis of homogenous and well-aligned ZnO nanorods on common conducting substrates without a seed layer. This method, based on the galvanic-cell structure, makes use of the contact potential between different materials as the driving force for ZnO growth. It is applicable to different conducting substrates at low temperature. More importantly, the as-grown ZnO nanorods show enhanced photoelectric response. This unique large scale low-temperature processing method could be of great importance for the application of ZnO nanostructures.

  1. A comprehensive biosensor integrated with a ZnO nanorod FET array for selective detection of glucose, cholesterol and urea.

    PubMed

    Ahmad, Rafiq; Tripathy, Nirmalya; Park, Jin-Ho; Hahn, Yoon-Bong

    2015-08-01

    We report a novel straightforward approach for simultaneous and highly-selective detection of multi-analytes (i.e. glucose, cholesterol and urea) using an integrated field-effect transistor (i-FET) array biosensor without any interference in each sensor response. Compared to analytically-measured data, performance of the ZnO nanorod based i-FET array biosensor is found to be highly reliable for rapid detection of multi-analytes in mice blood, and serum and blood samples of diabetic dogs. PMID:26111656

  2. Enhanced piezoelectric properties of vertically aligned single-crystalline NKN nano-rod arrays

    NASA Astrophysics Data System (ADS)

    Kang, Min-Gyu; Oh, Seung-Min; Jung, Woo-Suk; Gyu Moon, Hi; Baek, Seung-Hyub; Nahm, Sahn; Yoon, Seok-Jin; Kang, Chong-Yun

    2015-05-01

    Piezoelectric materials capable of converting between mechanical and electrical energy have a great range of potential applications in micro- and nano-scale smart devices; however, their performance tends to be greatly degraded when reduced to a thin film due to the large clamping force by the substrate and surrounding materials. Herein, we report an effective method for synthesizing isolated piezoelectric nano-materials as means to relax the clamping force and recover original piezoelectric properties of the materials. Using this, environmentally friendly single-crystalline NaxK1-xNbO3 (NKN) piezoelectric nano-rod arrays were successfully synthesized by conventional pulsed-laser deposition and demonstrated to have a remarkably enhanced piezoelectric performance. The shape of the nano-structure was also found to be easily manipulated by varying the energy conditions of the physical vapor. We anticipate that this work will provide a way to produce piezoelectric micro- and nano-devices suitable for practical application, and in doing so, open a new path for the development of complex metal-oxide nano-structures.

  3. Gigahertz Acoustic Vibrations of Elastically Anisotropic Indium-Tin-Oxide Nanorod Arrays.

    PubMed

    Guo, Peijun; Schaller, Richard D; Ocola, Leonidas E; Ketterson, John B; Chang, Robert P H

    2016-09-14

    Active control of light is important for photonic integrated circuits, optical switches, and telecommunications. Coupling light with acoustic vibrations in nanoscale optical resonators offers optical modulation capabilities with high bandwidth and small footprint. Instead of using noble metals, here we introduce indium-tin-oxide nanorod arrays (ITO-NRAs) as the operating media and demonstrate optical modulation covering the visible spectral range (from 360 to 700 nm) with ∼20 GHz bandwidth through the excitation of coherent acoustic vibrations in ITO-NRAs. This broadband modulation results from the collective optical diffraction by the dielectric ITO-NRAs, and a high differential transmission modulation up to 10% is achieved through efficient near-infrared, on-plasmon-resonance pumping. By combining the frequency signatures of the vibrational modes with finite-element simulations, we further determine the anisotropic elastic constants for single-crystalline ITO, which are not known for the bulk phase. This technique to determine elastic constants using coherent acoustic vibrations of uniform nanostructures can be generalized to the study of other inorganic materials. PMID:27526053

  4. Large-scale patterned ZnO nanorod arrays for efficient photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Hu, Yaping; Yan, Xiaoqin; Gu, Yousong; Chen, Xiang; Bai, Zhiming; Kang, Zhuo; Long, Fei; Zhang, Yue

    2015-06-01

    Nowadays, the fabrication of photoanodes with high light-harvesting capability and charge transfer efficiency is a key challenge for photoelectrochemical (PEC) water splitting. In this paper, large-scale patterned ZnO nanorod arrays (NRAs) were designed and fabricated via two-beam laser interference lithography and hydrothermal synthesis, which were further applied as PEC photoanodes for the first time. By adopting the ZnO NRA photoanodes with square pattern, the PEC cells achieved a maximum efficiency of 0.18%, which was improved 135% compared to the control group with no patterned ZnO NRAs. The large-scale highly ordered ZnO NRAs have enhanced light-harvesting ability due to the light-scattering effect. In addition, the enlarged surface area of the patterned ZnO NRAs accelerated the charge transfer at the photoanode/electrolyte interface. This research demonstrates an effective mean to realize the efficient solar water splitting, and the results suggest that large-scale highly ordered nanostructures are promising candidates in the field of energy harvesting.

  5. Extraordinarily high-rate capability of polyaniline nanorod arrays on graphene nanomesh

    NASA Astrophysics Data System (ADS)

    Gao, Shuangyan; Zang, Peiyu; Dang, Liqin; Xu, Hua; Shi, Feng; Liu, Zonghuai; Lei, Zhibin

    2016-02-01

    We report the high-rate capacitive performance of polyaniline (PANI) coated on graphene nanomesh (GNM). The PANI on GNM sheets shows vertical nanorod arrays that offer large electrochemically active surface area and numerous ion-accessible gaps. Benefiting from the highly pseudocapacitive PANI and ion-penetrable GNM, GNM-PANI with 70 wt% PANI exhibits a specific capacitance of 452 F g-1 at 1.0 A g-1, which remains at 404 F g-1 even at high discharge rate of 50 A g-1 in 1.0 M H2SO4. More importantly, a symmetric capacitor built with this electrode exhibits a relaxation time constant of 2.61 s, a value comparable to 2-5 s with activated carbon as electrode, and much shorter than 4-6 s of capacitors with chemically converted graphene as electrodes. The performance of GNM-PANI electrode reported herein is far superior to that of most other PANI-based electrodes, demonstrating that GNM is a promising scaffold that can help to realize the full potential of PANI due to its abundant in-plane nanopores.

  6. Enhanced piezoelectric properties of vertically aligned single-crystalline NKN nano-rod arrays

    PubMed Central

    Kang, Min-Gyu; Oh, Seung-Min; Jung, Woo-Suk; Gyu Moon, Hi; Baek, Seung-Hyub; Nahm, Sahn; Yoon, Seok-Jin; Kang, Chong-Yun

    2015-01-01

    Piezoelectric materials capable of converting between mechanical and electrical energy have a great range of potential applications in micro- and nano-scale smart devices; however, their performance tends to be greatly degraded when reduced to a thin film due to the large clamping force by the substrate and surrounding materials. Herein, we report an effective method for synthesizing isolated piezoelectric nano-materials as means to relax the clamping force and recover original piezoelectric properties of the materials. Using this, environmentally friendly single-crystalline NaxK1-xNbO3 (NKN) piezoelectric nano-rod arrays were successfully synthesized by conventional pulsed-laser deposition and demonstrated to have a remarkably enhanced piezoelectric performance. The shape of the nano-structure was also found to be easily manipulated by varying the energy conditions of the physical vapor. We anticipate that this work will provide a way to produce piezoelectric micro- and nano-devices suitable for practical application, and in doing so, open a new path for the development of complex metal-oxide nano-structures. PMID:25955763

  7. Enhanced piezoelectric properties of vertically aligned single-crystalline NKN nano-rod arrays.

    PubMed

    Kang, Min-Gyu; Oh, Seung-Min; Jung, Woo-Suk; Moon, Hi Gyu; Baek, Seung-Hyub; Nahm, Sahn; Yoon, Seok-Jin; Kang, Chong-Yun

    2015-01-01

    Piezoelectric materials capable of converting between mechanical and electrical energy have a great range of potential applications in micro- and nano-scale smart devices; however, their performance tends to be greatly degraded when reduced to a thin film due to the large clamping force by the substrate and surrounding materials. Herein, we report an effective method for synthesizing isolated piezoelectric nano-materials as means to relax the clamping force and recover original piezoelectric properties of the materials. Using this, environmentally friendly single-crystalline NaxK1-xNbO3 (NKN) piezoelectric nano-rod arrays were successfully synthesized by conventional pulsed-laser deposition and demonstrated to have a remarkably enhanced piezoelectric performance. The shape of the nano-structure was also found to be easily manipulated by varying the energy conditions of the physical vapor. We anticipate that this work will provide a way to produce piezoelectric micro- and nano-devices suitable for practical application, and in doing so, open a new path for the development of complex metal-oxide nano-structures. PMID:25955763

  8. Regularly patterned multi-section GaN nanorod arrays grown with a pulsed growth technique

    NASA Astrophysics Data System (ADS)

    Tu, Charng-Gan; Su, Chia-Ying; Liao, Che-Hao; Hsieh, Chieh; Yao, Yu-Feng; Chen, Hao-Tsung; Lin, Chun-Han; Weng, Chi-Ming; Kiang, Yean-Woei; Yang, C. C.

    2016-01-01

    The growth of regularly patterned multi-section GaN nanorod (NR) arrays based on a pulsed growth technique with metalorganic chemical vapor deposition is demonstrated. Such an NR with multiple sections of different cross-sectional sizes is formed by tapering a uniform cross section to another through stepwise decreasing of the Ga supply duration to reduce the size of the catalytic Ga droplet. Contrast line structures are observed in either a scanning electron microscopy or transmission electron microscopy image of an NR. Such a contrast line-marker corresponds to a thin Ga-rich layer formed at the beginning of GaN precipitation of a pulsed growth cycle and illustrates the boundary between two successive growth cycles in pulsed growth. By analyzing the geometry variation of the contrast line-markers, the morphology evolution in the growth of a multi-section NR, including a tapering process, can be traced. Such a morphology variation is controlled by the size of the catalytic Ga droplet and its coverage range on the slant facets at the top of an NR. The comparison of emission spectra between single-, two-, and three-section GaN NRs with sidewall InGaN/GaN quantum wells indicates that a multi-section NR can lead to a significantly broader sidewall emission spectrum.

  9. Co-occurrence of circular dichroism and asymmetric transmission in twist nanoslit-nanorod Arrays.

    PubMed

    Wang, Yongkai; Wen, Xiaojing; Qu, Yu; Wang, Li; Wan, Rengang; Zhang, Zhongyue

    2016-07-25

    Circular dichroism (CD) and asymmetric transmission (AT) are important in the field of negative refractive index media and perfect polarization converters. A large difference between T++ and T-- in the transmission matrix T leads to a large CD effect, whereas a large difference between T-+ and T+- leads to a large AT effect. To achieve large CD and AT effects simultaneously, we theoretically analyzed the transmission matrix T and proposed the chiral plasmonic nanostructure of twist nanoslit-nanorod arrays (TNNAs) in this study. Results calculated by the finite element method show that, at around resonant wavelengths, the spectra of T++ and T-- correspondingly present peaks and valleys leading to a large CD effect. Meanwhile one of the spectra for T-+ and T+- presents valleys and another presents peaks leading to a large AT effect. More importantly, the magnitude of CD is equivalent to that of AT. In addition, the CD and AT effects strongly depend on the geometric parameters of TNNAs. Overall, these results are useful for designing chiral plasmonic nanostructures with large CD and AT effects. PMID:27464094

  10. Controllable synthesis of branched hierarchical ZnO nanorod arrays for highly sensitive hydrazine detection

    NASA Astrophysics Data System (ADS)

    Hu, Jie; Zhao, Zhenting; Sun, Yongjiao; Wang, Ying; Li, Pengwei; Zhang, Wendong; Lian, Kun

    2016-02-01

    In this paper, three different kinds of ZnO nanostructures were successfully synthesized on Au/Glass (Au/G) substrate by electrochemical deposition method. The morphology and crystalline structures of the obtained samples were characterized using SEM, XRD and HRTEM. Electrochemical responses of the as-prepared ZnO based sensors to hydrazine in 0.1 M phosphate buffer solution (PBS, pH 7.4) were analyzed by cyclic voltammetry and single-potential amperometry. The results confirmed that the electrochemical performances of ZnO sensors are strongly dependent on the specific surface area. Especially, the branched hierarchical ZnO nanorod arrays shows the highest sensitivity of 5.35 μA μM-1 cm-2, a short response time of 3 s, a low detection limit of 0.08 μM with a linear hydrazine concentration response range from 0.8 μM to 101 μM, and it also exhibits excellent anti-interference, stability and reproducibility abilities, which provide great potential method of ZnO branched hierarchical structures in the development of high-performance electrochemical sensor.

  11. UV light sensing properties of Sm doped vertically aligned ZnO nanorod arrays

    SciTech Connect

    Kumar, D. Ranjith; Ranjith, K. S.; Rajendrakumar, R. T.

    2015-06-24

    Samarium doped ZnO nanorods were grown on silicon substrate by using vapor phase transport method (VPT) with the growth temperature of 950°C. The synthesized nanorods were characterized by XRD, field emission scanning electron microscopy, Raman spectra, and photocurrent measurements. The XRD result revealed that Sm was successfully doped into lattice plane of hexagonal ZnO nanorods. The FESEM result confirms the pure ZnO has nanorod like morphology with an average diameter and length of 130nm and 10µm respectively. The above observation is supported by the Micro-Raman spectroscopy result. The photocurrent in the visible region has been significantly enhanced due to deposition of Sm on the surface of the ZnO nanorods. Sm acts as a visible sensitizer because of its lower band gap compared to ZnO.

  12. Influence of TiO2 Nanorod Arrays on the Bilayered Photoanode for Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Cao, Ya; Li, Zhen; Wang, Yang; Zhang, Tao; Li, Yinchang; Liu, Xueqin; Li, Fei

    2016-06-01

    A TiO2 bilayered structure consisting of TiO2 nanoparticles (TiO2NP) as an overlayer and single-crystal rutile TiO2 nanorods (TiO2 NRs) as an underlayer on a transparent conductive fluorine-doped tin oxide substrate was designed as the photoanode of dye-sensitized solar cells (DSSCs) through a facile hydrothermal treatment followed by a doctor-blade method. DSSCs based on the hierarchical TiO2 nano-architecture photoelectrode shows a power conversion efficiency of 7.39% because the relatively large specific surface area of TiO2NP increased the dye absorption, and oriented one-dimensional TiO2 NRs enhanced the light harvesting capability, accelerating interfacial electron transport. In particular, we observed the growth morphology of the TiO2 nanorod arrays in the bilayered photoanode and the influence of the whole solar cell. The result indicated that the TiO2 NRs layer clearly impacted the photoelectron chemical properties, while the vertical and intensive nanorod arrays significantly increased their performance.

  13. Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process

    PubMed Central

    2012-01-01

    One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E2(H) mode intensity and increase of E1(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods. PMID:22768847

  14. Growth of Fe(3)O(4) nanorod arrays on graphene sheets for application in electromagnetic absorption fields.

    PubMed

    Zhang, Huanming; Zhu, Chunling; Chen, Yujin; Gao, Hong

    2014-08-01

    A facial strategy is developed to fabricate a three-dimensional (3D) Fe3 O4 nanorod array/graphene architecture, in which Fe3 O4 nanorods with a length and diameter of about 600 and 100 nm, respectively, are grown on both surfaces of the graphene sheets. The measured electromagnetic parameters show that the 3D architecture exhibits excellent electromagnetic wave-absorption properties, that is, more than 99 % of electromagnetic wave energy can be attenuated by the 3D architecture if it is added in only 20 wt % of the paraffin matrix, as the thickness of the absorber is in the range from 2.38 to 5.00 mm. The analysis of the electromagnetic (EM) absorption mechanism reveals that the excellent EM absorption properties are related to the special 3D architecture, and therefore, the construction of graphene-based 3D heteronanostructures is effective in obtaining lightweight EM absorbers with strong absorption properties. PMID:24827699

  15. Constructing n-ZnO@Au heterogeneous nanorod arrays on p-Si substrate as efficient photocathode for water splitting.

    PubMed

    Bao, Zhijia; Xu, Xiaoyong; Zhou, Gang; Hu, Jingguo

    2016-07-29

    Developing ingenious heterostructure photoelectrodes in photoelectrochemical (PEC) cells to both harvest more solar photons and steer desired charge separation flow is a prerequisite challenge for PEC water splitting. Herein a hierarchical p-Si/n-ZnO@Au heterostructure was constructed via large-area growth of one-dimensional (1D) ZnO nanorod arrays (NRAs) on p-Si substrate followed by decorating with Au nanoparticles (NPs), which exhibited remarkably improved photocathode activity for PEC water splitting relative to the bare Si and Si/ZnO NRAs photocathodes. In addition to structural superiorities of 1D NRAs, a series of dynamic contributions from complementary band-gap structure, p-n heterojunctions and Au plasmon towards photon harvesting and charge separation were demonstrated to ensure a well-steered collection of photoelectrons at the exposed ZnO nanorods and Au NPs, enabling substantially improved photocathode performance. PMID:27306198

  16. Constructing n-ZnO@Au heterogeneous nanorod arrays on p-Si substrate as efficient photocathode for water splitting

    NASA Astrophysics Data System (ADS)

    Bao, Zhijia; Xu, Xiaoyong; Zhou, Gang; Hu, Jingguo

    2016-07-01

    Developing ingenious heterostructure photoelectrodes in photoelectrochemical (PEC) cells to both harvest more solar photons and steer desired charge separation flow is a prerequisite challenge for PEC water splitting. Herein a hierarchical p-Si/n-ZnO@Au heterostructure was constructed via large-area growth of one-dimensional (1D) ZnO nanorod arrays (NRAs) on p-Si substrate followed by decorating with Au nanoparticles (NPs), which exhibited remarkably improved photocathode activity for PEC water splitting relative to the bare Si and Si/ZnO NRAs photocathodes. In addition to structural superiorities of 1D NRAs, a series of dynamic contributions from complementary band-gap structure, p–n heterojunctions and Au plasmon towards photon harvesting and charge separation were demonstrated to ensure a well-steered collection of photoelectrons at the exposed ZnO nanorods and Au NPs, enabling substantially improved photocathode performance.

  17. Combining 3-D plasmonic gold nanorod arrays with colloidal nanoparticles as a versatile concept for reliable, sensitive, and selective molecular detection by SERS.

    PubMed

    Yilmaz, Mehmet; Senlik, Erhan; Biskin, Erhan; Yavuz, Mustafa Selman; Tamer, Ugur; Demirel, Gokhan

    2014-03-28

    The detection of molecules at an ultralow level by Surface-Enhanced Raman Spectroscopy (SERS) has recently attracted enormous interest for various applications especially in biological, medical, and environmental fields. Despite the significant progress, SERS systems are still facing challenges for practical applications related to their sensitivity, reliability, and selectivity. To overcome these limitations, in this study, we have proposed a simple yet facile concept by combining 3-D anisotropic gold nanorod arrays with colloidal gold nanoparticles having different shapes for highly reliable, selective, and sensitive detection of some hazardous chemical and biological warfare agents in trace amounts through SERS. The gold nanorod arrays were created on the BK7 glass slides or silicon wafer surfaces via the oblique angle deposition (OAD) technique without using any template material or lithography technique and their surface densities were adjusted by manipulating the deposition angle (α). It is found that gold nanorod arrays fabricated at α = 10° exhibited the highest SERS enhancement in the absence of colloidal gold nanoparticles. Synergetic enhancement was obviously observed in SERS signals when combining gold nanorod arrays with colloidal gold nanoparticles having different shapes (i.e., spherical, rod, and cage). Due to their ability to produce localized surface plasmons (LSPs) in transverse and longitudinal directions, utilization of colloidal gold nanorods as a synergetic agent led to an increase in the enhancement factor by about tenfold compared to plain gold nanorod arrays. Moreover, we have tested our approach to detect some chemical and biological toxins namely dipicolinic acid (DIP), methyl parathion (MP), and diethyl phosphoramidate (DP). For all toxins, Raman spectra with high signal-to-noise ratios and reproducibility were successfully obtained over a broad concentration range (5 ppm-10 ppb). Our results suggest that the slightly tangled and

  18. Controllable hydrothermal synthesis of rutile TiO{sub 2} hollow nanorod arrays on TiCl{sub 4} pretreated Ti foil for DSSC application

    SciTech Connect

    Xi, Min; Zhang, Yulan; Long, Lizhen; Li, Xinjun

    2014-11-15

    Rutile TiO{sub 2} nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl{sub 4} pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO{sub 2} nanorod arrays (H-TNRs). The TiCl{sub 4} pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl{sub 4} concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ∼1.5 μm and diameter of ∼200 nm, obtained on 0.15 M TiCl{sub 4} pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl{sub 4}-TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode. - Graphical abstract: Rutile hollow TiO{sub 2} nanorod array photoanode obtained from original TiO{sub 2} nanorod array photoanode by hydrothermal etching demonstrates enhanced photoelectric efficiency of DSSC. - Highlights: • TiO{sub 2} nanorods are prepared via hydrothermal process on TiCl{sub 4}-pretreated Ti foil. • Hollow TiO{sub 2} nanorods are obtained by hydrothermal etching of TiO{sub 2} nanorods. • TiCl{sub 4} pretreatment plays a key role in protecting Ti foil from chemical corrosion. • Hollow TiO{sub 2} nanorods photoanode shows enhanced photoelectric efficiency for DSSC.

  19. Synthesis of novel AuPd nanoparticles decorated one-dimensional ZnO nanorod arrays with enhanced photoelectrochemical water splitting activity.

    PubMed

    Lu, Yan; Zhang, Junlong; Ge, Lei; Han, Changcun; Qiu, Ping; Fang, Siman

    2016-12-01

    The vertically aligned one-dimensional (1D) ZnO nanorod arrays decorated with AuPd alloy nanoparticles have been synthesized with ZnO nanorod arrays as template via a mild hydrothermal method. In this work, the as-prepared AuPd/ZnO nanorod arrays demonstrated high light-harvesting efficiency. The microstructures, morphologies and chemical properties of the obtained AuPd/ZnO composite photocatalyst were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS). The photoelectrochemical (PEC) performances of as-obtained AuPd/ZnO nanorod arrays were examined, and the photocurrent density was up to 0.98mAcm(-2) at 0.787V versus Ag/AgCl, which was about 2.4 times higher than the pure ZnO sample. A possible photocatalytic mechanism of the AuPd/ZnO hybrid nanostructures under the simulated sunlight irradiation was proposed to guide further improvement of other desirable materials. According to the above experiment results, it can be clearly found that AuPd/ZnO composite nanorod arrays showed excellent PEC performance and had promising applications in the utilization of solar energy. PMID:27552423

  20. Tailored Oxygen Framework of Li4Ti5O12 Nanorods for High-Power Li Ion Battery.

    PubMed

    Song, Kyeongse; Seo, Dong-Hwa; Jo, Mi Ru; Kim, Yong-Il; Kang, Kisuk; Kang, Yong-Mook

    2014-04-17

    Here we designed the kinetically favored Li4Ti5O12 by modifying its crystal structure to improve intrinsic Li diffusivity for high power density. Our first-principles calculations revealed that the substituted Na expanded the oxygen framework of Li4Ti5O12 and facilitated Li ion diffusion in Li4Ti5O12 through 3-D high-rate diffusion pathway secured by Na ions. Accordingly, we synthesized sodium-substituted Li4Ti5O12 nanorods having not only a morphological merit from 1-D nanostructure engineering but also sodium substitution-induced open framework to attain ultrafast Li diffusion. The new material exhibited an outstanding cycling stability and capacity retention even at 200 times higher current density (20 C) compared with the initial condition (0.1 C). PMID:26269981

  1. Tuning of defects in ZnO nanorod arrays used in bulk heterojunction solar cells

    PubMed Central

    2012-01-01

    With particular focus on bulk heterojunction solar cells incorporating ZnO nanorods, we study how different annealing environments (air or Zn environment) and temperatures impact on the photoluminescence response. Our work gives new insight into the complex defect landscape in ZnO, and it also shows how the different defect types can be manipulated. We have determined the emission wavelengths for the two main defects which make up the visible band, the oxygen vacancy emission wavelength at approximately 530 nm and the zinc vacancy emission wavelength at approximately 630 nm. The precise nature of the defect landscape in the bulk of the nanorods is found to be unimportant to photovoltaic cell performance although the surface structure is more critical. Annealing of the nanorods is optimum at 300°C as this is a sufficiently high temperature to decompose Zn(OH)2 formed at the surface of the nanorods during electrodeposition and sufficiently low to prevent ITO degradation. PMID:23186280

  2. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays

    PubMed Central

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-01-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials. PMID:26983501

  3. Growth and optical properties of ZnO nanorod arrays on Al-doped ZnO transparent conductive film

    PubMed Central

    2013-01-01

    ZnO nanorod arrays (NRAs) on transparent conductive oxide (TCO) films have been grown by a solution-free, catalyst-free, vapor-phase synthesis method at 600°C. TCO films, Al-doped ZnO films, were deposited on quartz substrates by magnetron sputtering. In order to study the effect of the growth duration on the morphological and optical properties of NRAs, the growth duration was changed from 3 to 12 min. The results show that the electrical performance of the TCO films does not degrade after the growth of NRAs and the nanorods are highly crystalline. As the growth duration increases from 3 to 8 min, the diffuse transmittance of the samples decreases, while the total transmittance and UV emission enhance. Two possible nanorod self-attraction models were proposed to interpret the phenomena in the sample with 9-min growth duration. The sample with 8-min growth duration has the highest total transmittance of 87.0%, proper density about 75 μm−2, diameter about 26 nm, and length about 500 nm, indicating that it can be used in hybrid solar cells. PMID:23566567

  4. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays

    NASA Astrophysics Data System (ADS)

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-03-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials.

  5. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays.

    PubMed

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-01-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials. PMID:26983501

  6. Highly Transparent and UV-Resistant Superhydrophobic SiO2-Coated ZnO Nanorod Arrays

    PubMed Central

    2015-01-01

    Highly transparent and UV-resistant superhydrophobic arrays of SiO2-coated ZnO nanorods are prepared in a sequence of low-temperature (<150 °C) steps on both glass and thin sheets of PET (2 × 2 in.2), and the superhydrophobic nanocomposite is shown to have minimal impact on solar cell device performance under AM1.5G illumination. Flexible plastics can serve as front cell and backing materials in the manufacture of flexible displays and solar cells. PMID:24495100

  7. ZnO nanorod-templated well-aligned ZrO2 nanotube arrays for fibroblast adhesion and proliferation

    NASA Astrophysics Data System (ADS)

    Lu, Zhisong; Zhu, Zhihong; Liu, Jinping; Hu, Weihua; Li, Chang Ming

    2014-05-01

    Cellular responses to porous tubular structures have recently been investigated in highly ordered ZrO2 nanotube arrays fabricated with anodization. However, the potential applications of the nanotube arrays are hindered by instrument requirements and substrate limitations, as well as by the complicated processes needed for synthesis. In this work, ZrO2 nanotube arrays were synthesized by in situ hydrolysis of zirconium propoxide with a zinc oxide nanorod array-based template. Fibroblast cells were able to grow on the nanotube array surface with produced elongated filopodia. Studies of the capability of cell growth and the expression of adhesion- and proliferation-related genes reveal that ZrO2 nanotube arrays may provide a better environment for cell adhesion and growth than a flat titanium surface. These findings not only provide fundamental insight into cell response to nanostructures but also provide an opportunity to use a unique approach to fabricate ZrO2 nanotube array structures for potential implant applications.

  8. Optimization of processing parameters on the controlled growth of ZnO nanorod arrays for the performance improvement of solid-state dye-sensitized solar cells

    SciTech Connect

    Lee, Yi-Mu; Yang, Hsi-Wen

    2011-03-15

    High-transparency and high quality ZnO nanorod arrays were grown on the ITO substrates by a two-step chemical bath deposition (CBD) method. The effects of processing parameters including reaction temperature (25-95 {sup o}C) and solution concentration (0.01-0.1 M) on the crystal growth, alignment, optical and electrical properties were systematically investigated. It has been found that these process parameters are critical for the growth, orientation and aspect ratio of the nanorod arrays, showing different structural and optical properties. Experimental results reveal that the hexagonal ZnO nanorod arrays prepared under reaction temperature of 95 {sup o}C and solution concentration of 0.03 M possess highest aspect ratio of {approx}21, and show the well-aligned orientation and optimum optical properties. Moreover the ZnO nanorod arrays based heterojunction electrodes and the solid-state dye-sensitized solar cells (SS-DSSCs) were fabricated with an improved optoelectrical performance. -- Graphical abstract: The ZnO nanorod arrays demonstrate well-alignment, high aspect ratio (L/D{approx}21) and excellent optical transmittance by low-temperature chemical bath deposition (CBD). Display Omitted Research highlights: > Investigate the processing parameters of CBD on the growth of ZnO nanorod arrays. > Optimization of CBD process parameters: 0.03 M solution concentration and reaction temperature of 95 {sup o}C. > The prepared ZnO samples possess well-alignment and high aspect ratio (L/D{approx}21). > An n-ZnO/p-NiO heterojunction: great rectifying behavior and low leakage current. > SS-DSSC has J{sub SC} of 0.31 mA/cm{sup 2} and V{sub OC} of 590 mV, and an improved {eta} of 0.059%.

  9. Growth of ZnO nanorod arrays by sol-gel method: transition from two-dimensional film to one-dimensional nanostructure

    NASA Astrophysics Data System (ADS)

    Zhu, M. W.; Huang, N.; Gong, J.; Zhang, B.; Wang, Z. J.; Sun, C.; Jiang, X.

    2011-04-01

    ZnO nanorod arrays were prepared by a sol-gel method in the present work. The effects of doping concentration and annealing time on the morphologies of ZnO:Al (ZAO) layers were investigated to clearly explore the growth process of ZnO nanorods by designing gradient structures and adjusting the annealing time. The results show that the doping level in the films is a key factor for the formation of nanorods and they cannot form at a low doping level. Out-of-plane anisotropic grain growth instead of the traditional in-plane coarsening process is observed with increasing annealing time. The growth model of nanorods is proposed in terms of the surface diffusion and Ehrlich-Schwoebel barrier (ES barrier) theory.

  10. Copper-ion-assisted growth of gold nanorods in seed-mediated growth: significant narrowing of size distribution via tailoring reactivity of seeds.

    PubMed

    Wen, Tao; Hu, Zhijian; Liu, Wenqi; Zhang, Hui; Hou, Shuai; Hu, Xiaona; Wu, Xiaochun

    2012-12-18

    In the well-developed seed-mediated growth of gold nanorods (GNRs), adding the proper amount of Cu(2+) ions in the growth solution leads to significant narrowing in the size distribution of the resultant GNRs, especially for those with shorter aspect ratios (corresponding longitudinal surface plasmon resonance (LSPR) peaks shorter than 750 nm). Cu(2+) ions were found to be able to catalyze the oxidative etching of gold seeds by oxygen, thus mediating subsequent growth kinetics of the GNRs. At proper Cu(2+) concentrations, the size distribution of the original seeds is greatly narrowed via oxidative etching. The etched seeds are highly reactive and grow quickly into desired GNRs with significantly improved size distribution. A similar mechanism can be employed to tune the end cap of the GNRs. Except for copper ions, no observable catalytic effect is observed from other cations presumably due to their lower affinity to oxygen. Considering the widespread use of seed-mediated growth in the morphology-controlled synthesis of noble metal nanostructures, the tailoring in seed reactivity we presented herein could be extended to other systems. PMID:23173599

  11. Direct growth of MnOOH nanorod arrays on a carbon cloth for high-performance non-enzymatic hydrogen peroxide sensing.

    PubMed

    Xu, Weina; Liu, Jianlin; Wang, Mingjun; Chen, Lin; Wang, Xue; Hu, Chenguo

    2016-03-24

    Novel MnOOH nanorod arrays directly growing on a flexible carbon cloth substrate (MnOOH/CC) is first synthesized through a facile hydrothermal technique and utilized as an electrocatalyst for non-enzymatic detection of hydrogen peroxide. The as-prepared MnOOH nanorods are uniformly distributed on the carbon cloth with a 3D porous network structure, which provides a high specific surface area and numerous electroactive sites. The electrode based on the carbon cloth-supported MnOOH nanorod arrays exhibits a higher sensitivity (692.42 μA mM(-1) cm(-2)) and a wider linear range (20 μm-9.67 mM) with a detection limit of 3.2 μM (S/N = 3) compared with the electrode based on the rigid graphite substrate supported the random distributed MnOOH nanorods. Further, the MnOOH/CC possesses an outstanding flexibility and can conveniently be assembled into the required shape for a specific use, thus the arc-shaped MnOOH/CC electrodes are fabricated whose electrocatalytic activity toward the hydrogen peroxide reduction remains nearly unchanged in comparison with the unbent state. Due to its excellent sensitivity, reproducibility, anti-interference and stability, the electrode based on the carbon cloth-supported MnOOH nanorod arrays is believed to be promising for applications in high efficiency flexible hydrogen peroxide sensing. PMID:26944997

  12. Tailoring magnetic properties in arrays of pulse-electrodeposited Co nanowires: The role of Cu additive

    NASA Astrophysics Data System (ADS)

    Esmaeili, A.; Almasi Kashi, M.; Ramazani, A.; Montazer, A. H.

    2016-01-01

    In this study, we aim to report the role of Cu additive in arrays of pulse-electrodeposited Co nanowires (NWs) with diameters from 30 to 75 nm, embedded in porous aluminum oxide templates. This features the role of Cu additive in composition and crystalline characteristics as well as in the magnetic properties of Co NWs. Increasing the duration of off-time between pulses during the electrodeposition of Co NWs made it possible to increase the amount of Cu content, so that Co-rich CoCu NWs were obtained. The parallel coercivity and squareness values increased up to 1500 Oe and 0.8 for 30 nm diameter Co94Cu6 NWs, starting from 500 Oe and 0.3 for pure Co NWs. On the other hand, although there was a substantial difference between the crystalline characteristics of 75 nm diameter pure Co and CoCu NWs, no considerable change in their magnetic properties was observed using hysteresis loop measurements. In this respect, the first-order reversal curve (FORC) analysis revealed strong inter-wire magnetostatic interactions for the CoCu NWs. Moreover, we studied the effect of thermal annealing, which resulted in an increase in the coercivity of CoCu NWs with different diameters up to 15%. As a result, the addition of small amount of Cu provides an alternative approach to tailoring the magnetic properties of Co NWs.

  13. Organic transistors with ordered nanoparticle arrays as a tailorable platform for selective, in situ detection.

    PubMed

    Hammock, Mallory L; Sokolov, Anatoliy N; Stoltenberg, Randall M; Naab, Benjamin D; Bao, Zhenan

    2012-04-24

    The use of organic transistors as sensing platforms provides a number of distinct advantages over conventional detection technologies, including their tunability, portability, and ability to directly transduce binding events without tedious and expensive labeling procedures. However, detection efforts using organic transistors lack a general method to uniquely specify and detect a target of interest. While highly sensitive liquid- and vapor-phase sensors have been previously reported, detection has been restricted either to the serendipitous interaction of the analyte molecules with the organic semiconductor or to the covalent functionalization of the semiconductor with receptor groups to enhance specificity. However, the former technique cannot be regularly relied upon for tailorable sensing while the latter may result in unpredictable decreases in electronic performance. Thus, a method to provide modular receptor sites on the surface of an organic transistor without damaging the device will significantly advance the field, especially regarding biological species detection. In this work, we utilized a block copolymer to template ordered, large-area arrays of gold nanoparticles, with sub-100 nm center-to-center spacing onto the surface of an organic transistor. This highly modular platform is designed for orthogonal modification with a number of available chemical and biological functional groups by taking advantage of the well-studied gold-thiol linkage. Herein, we demonstrate the functionalization of gold nanoparticles with a mercury-binding oligonucleotide sequence. Finally, we demonstrate the highly selective and robust detection of mercury(II) using this platform in an underwater environment. PMID:22397363

  14. Optical phonon modes in ordered core-shell CdSe/CdS nanorod arrays

    NASA Astrophysics Data System (ADS)

    Giugni, Andrea; Das, Gobind; Alabastri, Alessandro; Zaccaria, Remo Proietti; Zanella, Marco; Franchini, Isabella; di Fabrizio, Enzo; Krahne, Roman

    2012-03-01

    We investigate the optical phonons in “dot-in-a-rod” core-shell CdSe/CdS nanorods at wavelengths resonant with the optical transitions either in the core or in the shell. At a wavelength above the CdS band gap, only CdS phonon modes were detected. In contrast, at excitation in resonance with the core transitions, we observed phonon modes of both the CdSe core and the CdS shell. In laterally ordered nanorod assemblies, the CdS longitudinal-optical phonon mode manifested a low-energy shoulder that could be related to higher-order longitudinal-optical phonon modes. Furthermore, we report on surface-optical modes that originate from the tracklike superstructure of the nanorod assemblies.

  15. Strongly coupled metal oxide nanorod arrays with graphene nanoribbons and nanosheets enable novel solid-state hybrid cells

    NASA Astrophysics Data System (ADS)

    Xiao, Junwu; Xi, Jiangbo; Xu, Yangyang; Yang, Shihe; Jin, Yunxia; Xiao, Fei; Wang, Shuai

    2015-06-01

    Electrochemical capacitors and rechargeable batteries are still limited in applications by the low energy and power densities they can deliver, respectively, holding back their deployment in electric vehicles. Here we develop a type of solid-state hybrid cells (SHCs) composed of graphene nanoribbons and nanosheets-coated metal oxide nanorod arrays ((MOx/GNR)@GNS). GNR and GNS are deposited on the surface of MOx nanorod arrays to improve the electron transport characteristic, and thus enhance the energy storage performance. The (MOx/GNR)@GNS-based SHCs can achieve a maximum volumetric energy density of 0.9 mWh cm-3, and still retain 0.4 mWh cm-3 even at 0.1 W cm-3. The energy storage performance is much better than the electrochemical capacitors reported previously, and can even rival the commercial Li thin-film battery but with a significantly higher power density, lower cost and higher safety. Also demonstrated is the good long-term cycle life with only ∼17% loss after 2500 cycles. These salient features make the (MOx/GNR)@GNS composites-based SHCs a strong contender for electrochemical energy storage.

  16. Electrochemical sensing of glucose by carbon cloth-supported Co3O4/PbO2 core-shell nanorod arrays.

    PubMed

    Chen, Ting; Li, Xiaowei; Qiu, Cuicui; Zhu, Wencai; Ma, Houyi; Chen, Shenhao; Meng, Oliver

    2014-03-15

    A novel electrochemical sensor for the detection of glucose was constructed based on the use of Co3O4/PbO2 core-shell nanorod arrays as electrocatalysts. In this paper the Co3O4/PbO2 core-shell nanorod arrays grow directly on a flexible carbon cloth substrate by the combination of hydrothermal synthesis and electrochemical deposition methods. The as-prepared hierarchical nanocomposites show the structural characteristics of nanowire core and nanoparticle shell. The carbon cloth-supported Co3O4/PbO2 nanorod array electrode exhibits higher sensitivity (460.3 μA mM(-1)cm(-2) in the range from 5 μM to 1.2mM) and lower detection limit (0.31 μM (S/N=3)) than the carbon cloth-supported Co3O4 nanowire array electrode. Both the three-dimensional network of carbon cloth substrate and the hierarchical nanostructure of binary Co3O4/PbO2 composites make such an electrode have high electrocatalytic activity towards the glucose oxidation. Due to the excellent sensitivity, repeatability and anti-interference ability, the carbon cloth-supported Co3O4/PbO2 nanorod arrays will be the promising materials for fabricating practical non-enzymatic glucose sensors. PMID:24140837

  17. Effect of TiO2 blocking layer on TiO2 nanorod arrays based dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Sivakumar, R.; Paulraj, M.

    2016-05-01

    Highly ordered rutile titanium dioxide nanorod (TNR) arrays (1.2 to 6.2 μm thickness) were grown on TiO2 blocking layer chemically deposited on fluorine doped tin oxide (FTO) substrate and were used as photo-electrodes to fabricate dye sensitized solar cells (DSSC's). Homogeneous layer of TiO2 on FTO was achieved by using aqueous peroxo- titanium complex (PTC) solutions via chemical bath deposition. Structural and morphological properties of the prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) measurements. TNR arrays (6.2 μm) with TiO2 blocking layer showed higher energy conversion efficiency (1.46%) than that without TiO2 blocking layer. The reason can be ascertained to the suppression of electron-hole recombination at the semiconductor/electrolyte interface by the effect of TiO2 blocking layer.

  18. Photoelectrochemical characteristics of TiO2 nanorod arrays grown on fluorine doped tin oxide substrates by the facile seeding layer assisted hydrothermal method

    NASA Astrophysics Data System (ADS)

    Sui, Mei-rong; Han, Cui-ping; Gu, Xiu-quan; Wang, Yong; Tang, Lu; Tang, Hui

    2016-05-01

    TiO2 nanorod arrays (NRAs) were prepared on fluorine doped tin oxide (FTO) substrates by a facile two-step hydrothermal method. The nanorods were selectively grown on the FTO regions which were covered with TiO2 seeding layer. It took 5 h to obtain the compact arrays with the nanorod length of ~2 μm and diameter of ~50 nm. The photoelectrochemical (PEC) properties of TiO2 NRAs are also investigated. It is demonstrated that the TiO2 NRAs indicate the good photoelectric conversion ability with an efficiency of 0.22% at a full-wavelength irradiation. A photocurrent density of 0.21 mA/cm2 is observed at 0.7 V versus the saturated calomel electrode (SCE). More evidences suggest that the charge transferring resistance is lowered at an irradiation, while the flat-band potential ( V fb) is shifted towards the positive side.

  19. Synthesis and optical characteristics of yttrium-doped zinc oxide nanorod arrays grown by hydrothermal method.

    PubMed

    Park, Hyunggil; Kim, Younggyu; Ji, Iksoo; Lee, Sang-Heon; Kim, Jin Soo; Kim, Jin Soo; Leem, Jae-Young

    2014-11-01

    Yttrium-doped ZnO (YZO) nanorods were synthesized by hydrothermal growth on a quartz substrate with various post-annealing temperatures. To investigate the effects of post-annealing on the optical properties and parameters of the nanorods, X-ray diffractometry (XRD), photoluminescence (PL) measurement, and ultraviolet (UV)-visible spectroscopy were used. From the XRD investigation, the full width at half maximum (FWHM) and the dislocation density of the nanorods was found to increase with an increase in the post-annealing temperature. In the PL spectra, the intensity of the near band edge (NBE) emission peak in the UV region also increases with an increase in the temperature of post-annealing. The deep level emission (DLE) peak in the visible region changes with various post-annealing temperatures, and its intensity increases remarkably with post-annealing at 800 degrees C. In this paper, changes in the optical parameters of the nanorods caused by variation in the behavior of Y during post-annealing was investigated, with properties such as absorption coefficients, refractive indices, and dispersion parameters being obtained from transmittance and reflectance analysis. PMID:25958523

  20. One-step growth of well-aligned TiO2 nanorod arrays for flexible dye-sensitized solar cells.

    PubMed

    Chen, Xiaoxu; Tang, Qunwei; Zhao, Zhiyuan; Wang, Xinghui; He, Benlin; Yu, Liangmin

    2015-02-01

    We present here the feasibility of growing well-aligned TiO2 nanorod arrays by a dc reactive magnetron sputtering strategy for flexible dye-sensitized solar cells. These flexible devices yield an efficiency of 5.3% in comparison to 1.2% from traditional TiO2 nanoparticles by a low-temperature technique. PMID:25531300

  1. Hydrogen treatment-improved uniform deposition of Ag nanoparticles on ZnO nanorod arrays and their visible-light photocatalytic and surface-enhanced Raman scattering properties

    PubMed Central

    2013-01-01

    ZnO nanorod arrays were synthesized by chemical bath deposition. After heat treatment in hydrogen or air, Ag nanoparticles were deposited on ZnO nanorod arrays by photo-reduction method. The size of Ag nanoparticles as well as the surface morphology, structure, composition, and optical property of ZnO nanorod arrays before and after the deposition of Ag nanoparticles were characterized by SEM, XRD, EDS, and UV/VIS/NIR spectrophotometer. As compared to the samples with heat treatment in air or without heat treatment, the ZnO nanorod arrays after heat treatment in hydrogen allowed Ag nanoparticles to be deposited more uniformly, densely, and numerously. Also, they exhibited higher efficiency for the visible light-driven photocatalytic degradation of Rhodamine 6G (R6G) dye. The effects of the amount of Ag nanoparticles, initial dye concentration, and temperature on the photocatalytic degradation efficiency were investigated. Furthermore, they also exhibited better surface-enhanced Raman scattering property for the detection of R6G dyes. PMID:23866904

  2. Fe2O3–TiO2 core–shell nanorod arrays for visible light photocatalytic applications

    SciTech Connect

    Yao, Kun; Basnet, Pradip; Sessions, Henry; Larsen, George K.; Murph, Simona E. Hunyadi; Zhao, Yiping

    2015-11-11

    By using the glancing angle deposition technique and post-deposition annealing, Fe2O3–TiO2 core-shell nanorod arrays with specific crystalline states can be designed and fabricated. The Fe2O3–TiO2 core-shell samples annealed at temperatures greater than 450°C formed α-Fe2O3 and anatase TiO2, and showed higher catalytic efficiency for the degradation of methylene blue (MB) under visible light illumination when compared with pure anatase TiO2 or α-Fe2O3 nanorod arrays. Solar conversion of carbon dioxide and water vapor in the presence of Fe2O3–TiO2 core-shell nanorod arrays was also investigated. Carbon monoxide, hydrogen, methane, and methanol along with other hydrocarbons were produced after only several hours’ exposure under ambient sunlight. It was determined that the core-shell structure showed greater efficiency for solar CO2 conversion than the pure TiO2 nanorod arrays.

  3. CdS nanorods/organic hybrid LED array and the piezo-phototronic effect of the device for pressure mapping

    NASA Astrophysics Data System (ADS)

    Bao, Rongrong; Wang, Chunfeng; Dong, Lin; Shen, Changyu; Zhao, Kun; Pan, Caofeng

    2016-04-01

    As widely applied in light-emitting diodes and optical devices, CdS has attracted the attention of many researchers due to its nonlinear properties and piezo-electronic effect. Here, we demonstrate a LED array composed of PEDOT:PSS and CdS nanorods and research the piezo-photonic effect of the array device. The emission intensity of the device depends on the electron-hole recombination at the interface of the p-n junction which can be adjusted using the piezo-phototronic effect and can be used to map the pressure applied on the surface of the device with spatial resolution as high as 1.5 μm. A flexible LED device array has been prepared using a CdS nanorod array on a Au/Cr/kapton substrate. This device may be used in the field of strain mapping using its high pressure spatial-resolution and flexibility.As widely applied in light-emitting diodes and optical devices, CdS has attracted the attention of many researchers due to its nonlinear properties and piezo-electronic effect. Here, we demonstrate a LED array composed of PEDOT:PSS and CdS nanorods and research the piezo-photonic effect of the array device. The emission intensity of the device depends on the electron-hole recombination at the interface of the p-n junction which can be adjusted using the piezo-phototronic effect and can be used to map the pressure applied on the surface of the device with spatial resolution as high as 1.5 μm. A flexible LED device array has been prepared using a CdS nanorod array on a Au/Cr/kapton substrate. This device may be used in the field of strain mapping using its high pressure spatial-resolution and flexibility. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00431h

  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. Enhanced Bulk and Interfacial Charge Transfer Dynamics for Efficient Photoelectrochemical Water Splitting: The Case of Hematite Nanorod Arrays.

    PubMed

    Wang, Jian; Feng, Bo; Su, Jinzhan; Guo, Liejin

    2016-09-01

    Charge transport in the bulk and across the semiconductor/electrolyte interface is one of the major issues that limits photoelectrochemical (PEC) performance in hematite photoelectrodes. Efficient charge transport in the entire hematite is of great importance to obtaining high photoelectrochemical properties. Herein, to reach this goal, we employed both TiO2 underlayer and overlayer deposition on hematite nanorod films, followed by a fast annealing treatment. The TiO2 underlayer and overlayer not only serve as dopant sources for carrier density increase but also reduce charge recombination at the fluorine-doped tin oxide (FTO)/hematite interface and accelerate charge transfer across the hematite/electrolyte interface. This synergistic doping and interface modifying effects give rise to an enhanced photoelectrochemical water oxidation performance of hematite nanorod arrays, generating an impressive photocurrent density of 1.49 mA cm(-2) at 1.23 V vs RHE. This is the first report on using both underlayer and overlayer modification with the same material to improve charge transport through the entire electron transport path in hematite, which provides a novel way to manipulate charge transfer across the semiconductor interface for a high-performance photoelectrode. PMID:27508404

  6. Synthesis and photoelectrochemical response of CdS quantum dot-sensitized TiO2 nanorod array photoelectrodes

    PubMed Central

    2013-01-01

    A continuous and compact CdS quantum dot-sensitive layer was synthesized on TiO2 nanorods by successive ionic layer adsorption and reaction (SILAR) and subsequent thermal annealing. The thickness of the CdS quantum dot layer was tuned by SILAR cycles, which was found to be closely related to light absorption and carrier transformation. The CdS quantum dot-sensitized TiO2 nanorod array photoelectrodes were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet–visible absorption spectroscopy, and photoelectrochemical property measurement. The optimum sample was fabricated by SILAR in 70 cycles and then annealed at 400°C for 1 h in air atmosphere. A TiO2/CdS core-shell structure was formed with a diameter of 35 nm, which presented an improvement in light harvesting. Finally, a saturated photocurrent of 3.6 mA/cm2 was produced under the irradiation of AM1.5G simulated sunlight at 100 mW/cm2. In particular, the saturated current density maintained a fixed value of approximately 3 mA/cm2 without decadence as time passed under the light conditions, indicating the steady photoelectronic property of the photoanode. PMID:23663590

  7. ZnO/Ag composite nanorod arrays for surface-plasmon-enhanced emission study

    SciTech Connect

    Pal, Anil Kumar E-mail: d.bharathimohan@gmail.com; Mohan, D. Bharathi E-mail: d.bharathimohan@gmail.com

    2014-04-24

    The surface plasmon resonance enhanced emission through coupling of surface plasmons and exciton band energies is studied in hybrid ZnO/Ag nanostructure. The catalytic growth of ZnO nanorods is controlled in seed mediated growth by altering size distribution of Ag nanoislands. X-ray diffraction shows a predominant (002) crystal plane confirming the preferential growth of ZnO nanorods on as-deposited Ag. Increase of surface roughness in Ag film by post deposition annealing process enhances the light emission due to momentum matching between surface plasmons and excitons as well as a red shift of 32 meV occurs due to multi phonon and phonon-exciton interaction.

  8. Low-temperature growth and characterization of single crystalline ZnO nanorod arrays using a catalyst-free inductively coupled plasma-metal organic chemical vapor deposition.

    PubMed

    Jeong, Sang-Hun; Lee, Chang-Bae; Moon, Won-Jin; Song, Ho-Jun

    2008-10-01

    Vertically aligned ZnO nanorod arrays have been synthesized on c-plane sapphires at a low temperature of 400 degrees C using catalyst-free inductively coupled plasma (ICP) metal organic chemical vapor deposition (MOCVD) technique by varying the ICP powers. Diameters of the ZnO nanorods changed from 200 nm to 400 nm as the ICP power increased from 200 to 400 Watt. TEM and XRD investigations indicated that the ZnO nanorod arrays grown at ICP powers above 200 Watt had a homogeneous in-plane alignment and single crystalline nature. PL study at room temperature (RT) and 6 K confirmed that the ZnO nanorod arrays in the present study are of high optical quality as well as good crystalline quality, showing only exciton-related emission peaks without any trace of defect-related deep level emissions in visible range. The blueshift of exciton emission peak in RTPL spectra was also found as rod diameter decreased and it is deduced that this shift in emission energy may be due to the surface resonance effect resulted from the increased surface-to-volume ratio, based on the observation and behavior of the surface exciton (SX) emission in the high-resolution 6 K PL spectra. PMID:19198399

  9. Study on the photogenerated charge transfer and photoelectrocatalytic performance of Ag/ZnO nanorod arrays under the irradiation of simulated sun light

    NASA Astrophysics Data System (ADS)

    Mu, Zhao; Yan, Weiping; Zhao, Rusong; Lin, Yanhong

    2015-06-01

    Ag/ZnO nanorod arrays with enhanced photoelectric response properties under simulated sun light were synthesized by a facile two-step process and characterized by x-ray powder diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS) and the field emission scanning electron microscopy (FESEM). The photoelectrocatalytic (PEC) activities of the catalysts were evaluated by degrading efficiency of methylene blue (MB) dye under simulated sun light. The MB removal rate can reach 85% after the irradiation of simulated sunlight for 30 min. Surface photovoltage (SPV) measurements and transient photovoltage (TPV) spectra demonstrated that Ag loading improved the utilization of the visible spectral absorption of ZnO nanorod arrays, as well as their separation efficiency of photogenerated electron-hole pairs, which may be due to the capture effect of Ag nanoparticles for free electrons under the irradiation of simulated sunlight. The photoelectrochemical investigations indicated that the Ag/ZnO nanorod arrays showed enhanced photocurrent generation efficiency, and had a more effective interface charge transfer path. The fast PEC degradation of MB is ascribed to the highly ordered nanorod architecture, the large effective mass of the photogenerated holes on the surface of ZnO induced by Ag nanoparticles loading, as well as the effective transport of photogenerated charge carriers under the effect of external electric field.

  10. Well-integrated ZnO nanorod arrays on conductive textiles by electrochemical synthesis and their physical properties

    PubMed Central

    2013-01-01

    We reported well-integrated zinc oxide (ZnO) nanorod arrays (NRAs) on conductive textiles (CTs) and their structural and optical properties. The integrated ZnO NRAs were synthesized by cathodic electrochemical deposition on the ZnO seed layer-coated CT substrate in ultrasonic bath. The ZnO NRAs were regularly and densely grown as well as vertically aligned on the overall surface of CT substrate, in comparison with the grown ZnO NRAs without ZnO seed layer or ultrasonication. Additionally, their morphologies and sizes can be efficiently controlled by changing the external cathodic voltage between the ZnO seed-coated CT substrate and the counter electrode. At an external cathodic voltage of −2 V, the photoluminescence property of ZnO NRAs was optimized with good crystallinity and high density. PMID:23316935

  11. Well-integrated ZnO nanorod arrays on conductive textiles by electrochemical synthesis and their physical properties.

    PubMed

    Ko, Yeong Hwan; Kim, Myung Sub; Park, Wook; Yu, Jae Su

    2013-01-01

    We reported well-integrated zinc oxide (ZnO) nanorod arrays (NRAs) on conductive textiles (CTs) and their structural and optical properties. The integrated ZnO NRAs were synthesized by cathodic electrochemical deposition on the ZnO seed layer-coated CT substrate in ultrasonic bath. The ZnO NRAs were regularly and densely grown as well as vertically aligned on the overall surface of CT substrate, in comparison with the grown ZnO NRAs without ZnO seed layer or ultrasonication. Additionally, their morphologies and sizes can be efficiently controlled by changing the external cathodic voltage between the ZnO seed-coated CT substrate and the counter electrode. At an external cathodic voltage of -2 V, the photoluminescence property of ZnO NRAs was optimized with good crystallinity and high density. PMID:23316935

  12. Preparation and XRD analyses of Na-doped ZnO nanorod arrays based on experiment and theory

    NASA Astrophysics Data System (ADS)

    Yang, X. P.; Lu, J. G.; Zhang, H. H.; Chen, Y.; Kan, B. T.; Zhang, J.; Huang, J.; Lu, B.; Zhang, Y. Z.; Ye, Z. Z.

    2012-03-01

    ZnO nanorod arrays (NRAs) with different Na contents were prepared by thermal evaporation. Sodium pyrophosphate was adopted as the Na source. The Na contents in NRAs were determined by X-ray photoelectron spectra to be 0, 6.1, and 9.4 at.%. X-ray diffraction (XRD) analyses of Na-doped ZnO NRAs were performed in experiment and by first-principle calculation with the assumption of Na substitutions. A couple of typical changes were found in XRD patterns of Na-doped ZnO. The simulation results well agreed with the experimental data, which revealed that Na mainly located at the substitutional sites in Na-doped ZnO NRAs.

  13. Well-integrated ZnO nanorod arrays on conductive textiles by electrochemical synthesis and their physical properties

    NASA Astrophysics Data System (ADS)

    Ko, Yeong Hwan; Kim, Myung Sub; Park, Wook; Yu, Jae Su

    2013-01-01

    We reported well-integrated zinc oxide (ZnO) nanorod arrays (NRAs) on conductive textiles (CTs) and their structural and optical properties. The integrated ZnO NRAs were synthesized by cathodic electrochemical deposition on the ZnO seed layer-coated CT substrate in ultrasonic bath. The ZnO NRAs were regularly and densely grown as well as vertically aligned on the overall surface of CT substrate, in comparison with the grown ZnO NRAs without ZnO seed layer or ultrasonication. Additionally, their morphologies and sizes can be efficiently controlled by changing the external cathodic voltage between the ZnO seed-coated CT substrate and the counter electrode. At an external cathodic voltage of -2 V, the photoluminescence property of ZnO NRAs was optimized with good crystallinity and high density.

  14. Well-aligned Nd-doped SnO2 nanorod layered arrays: preparation, characterization and enhanced alcohol-gas sensing performance.

    PubMed

    Qin, Guohui; Gao, Fan; Jiang, Qiuping; Li, Yuehua; Liu, Yongjun; Luo, Li; Zhao, Kang; Zhao, Heyun

    2016-02-21

    Well-oriented neodymium doped SnO2 layered nanorod arrays were synthesized by a substrate-free hydrothermal route using sodium stannate and sodium hydroxide at 210 °C. The morphology and phase structure of the Nd-doped SnO2 nanoarrays were investigated by X-ray powder diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman scattering spectroscopy, X-ray photoelectron spectroscopy and the BET method. The results demonstrated that the Nd-doped SnO2 layered nanorod arrays showed a unique nanostructure combined together with double layered arrays of nanorods with a diameter of 12 nm and a length of several hundred nanometers. The Nd-doped layered SnO2 nanoarrays kept the crystal structure of the bulk SnO2 and possessed more surface defects caused by the Nd ions doped into the SnO2 lattice. The Nd dopant acts as a crystallite growth inhibitor to prevent the growth of SnO2 nanorods. An investigation into the gas-sensing properties indicated that the optimized doping level of 3.0 at% Nd-doped SnO2 layered nanorod arrays exhibited an excellent sensing response toward alcohol at a lower temperature of 260 °C. The enhanced sensor performance was attributed to the higher specific surface area, multi-defect surface structure and the excellent catalytic properties of Nd dopant that is able to increase the amount of active sites on the surface of semiconducting oxides. The Nd-doped SnO2 nanoarray sensors were considered to be a promising candidate for trace alcohol detections in environmental gas monitoring. PMID:26863493

  15. Optical study and ruthenizer (II) N3 dye-sensitized solar cell application of ZnO nanorod-arrays synthesized by combine two-step process

    NASA Astrophysics Data System (ADS)

    Parra, Mohammad Ramzan; Haque, Fozia Z.

    2015-10-01

    Highly dense ZnO nanorod-arrays were successfully synthesized with uniform c-axis growth by using combine two-step process: sol-gel spin coating followed by the aqueous solution growth method. Structural and optical properties of ZnO nanorod-arrays were investigated. The X-ray diffraction results revealed that ZnO nanorod arrays exhibit wurtzite hexagonal crystal structure with a dominant (002) peak with high crystallinity. Nanorods of 3-4 μm length and 500 nm diameter, with surface roughness ˜20 nm were observed. Furthermore, Raman spectroscopic results revealed the presence of E 2 peak ˜438 cm-1 which again corroborated the existence of wurtzite crystal structures assigned to ZnO. The optical transmittance spectrum indicated that the transmittance of more than 80% was observed in the visible and infrared (IR) regions with the optical band-gap energy ˜3.35 eV. Photoluminescence spectrum showed peaks in ultra-violet (382.0 nm) and green region (524.9 nm), which specified good-quality crystallite formation containing high density of surface defects, zinc interstitials and oxygen-vacancies. Ruthenizer (II) N3-dye loaded sensitized solar cell test illustrated that the uniform ZnO nanorod-arrays as working electrode with a short circuit current density of 3.99 mA/cm2, fill factor ˜50% and overall power conversion efficiency (η) ˜1.36% might be a promising electrode material of dye sensitized solar cell application.

  16. Resistive switching characteristics of a compact ZnO nanorod array grown directly on an Al-doped ZnO substrate

    NASA Astrophysics Data System (ADS)

    Yoo, E. J.; Shin, J. Y.; Yoon, T. S.; Kang, C. J.; Choi, Y. J.

    2016-07-01

    ZnO’s resistive switching properties have drawn much attention because ZnO has a simple chemical composition and is easy to manipulate. The propulsion mechanism for resistive switching in ZnO is based on a conducting filament that consists of oxygen vacancies. In the case of film structure, the random formation of the conducting filaments occasionally leads to unstable switching characteristics. Limiting the direction in which the conducting filaments are formed is one way to solve this problem. In this study, we demonstrate reliable resistive switching behavior in a device with an Au/compact ZnO nanorod array/Al-doped ZnO structure with stable resistive switching over 105 cycles and a long retention time of 104 s by confining conducting filaments along the boundaries between ZnO nanorods. The restrictive formation of conducting filaments along the boundaries between ZnO nanorods is observed directly using conductive atomic force microscopy.

  17. Electrochemical flow-based solution-solid growth of the Cu2O nanorod array: potential application to lithium ion batteries.

    PubMed

    Shin, Jeong Ho; Park, Sun Hwa; Hyun, Seung Min; Kim, Jeong Won; Park, Hyun Min; Song, Jae Yong

    2014-09-14

    The catalyzed solution-liquid-solid (SLS) growth has been well developed to synthesize semiconductor nanowires with controlled diameters. The SLS growth occurs in the longitudinal direction of nanowires, due to the directional anisotropy driven by the metal catalysts where chemical precursors are introduced. In the present study, we report a selective, template-free, and environmentally-friendly electrochemical flow-based solution-solid (electrochemical flow-SS) growth of the Cu2O nanorod array. The anisotropy for directional growth without any catalysts is generated by the electrical field in a flowing electrolyte of ultra-dilute CuSO4. The filamentary anisotropy originates from electric field enhancement on pyramidal nanocrystals in the electrolyte of low ionic conductivity (13 μS cm(-1)). The Cu2O and Cu nanorods are able to be selectively synthesized by controlling the electrolyte pH and oxygen dissolution into the electrolyte. The synthesized Cu2O nanorod array shows excellent electrochemical properties as an anode material for lithium-ion batteries; the specific capacities increase from 323 to 1206 mA h g(-1) during 500 cycles. The capacity enhancement is due to the phase transformation from Cu2O to CuO, nano-restructuring of nanorods into fragmented nanoparticles, and the progressive generation of an electroactive polymeric gel-like layer on the surface of the nanoparticles. The electrochemical flow-SS growth of Cu2O nanorods is expected to contribute to further development of other functional nanorods. PMID:25055242

  18. Enhanced field electron emission from aligned diamond-like carbon nanorod arrays prepared by reactive ion beam etching

    NASA Astrophysics Data System (ADS)

    Zhao, Yong; Qin, Shi-Qiao; Zhang, Xue-Ao; Chang, Sheng-Li; Li, Hui-Hui; Yuan, Ji-Ren

    2016-05-01

    Homogeneous diamond-like carbon (DLC) films were deposited on Si supports by a pulsed filtered cathodic vacuum arc deposition system. Using DLC films masked by Ni nanoparticles as precursors, highly aligned diamond-like carbon nanorod (DLCNR) arrays were fabricated by the etching of inductively coupled radio frequency oxygen plasma. The as-prepared DLCNR arrays exhibit excellent field emission properties with a low turn-on field of 2.005 V μm‑1 and a threshold field of 4.312 V μm‑1, respectively. Raman spectroscopy and x-ray photoelectron spectroscopy were employed to determine the chemical bonding structural change of DLC films before and after etching. It is confirmed that DLC films have good connection with Si supports via the formation of the SiC phase, and larger conductive sp2 domains are formed in the as-etched DLC films, which play essential roles in the enhanced field emission properties for DLCNR arrays.

  19. Facet recovery and light emission from GaN/InGaN/GaN core-shell structures grown by metal organic vapour phase epitaxy on etched GaN nanorod arrays

    NASA Astrophysics Data System (ADS)

    Le Boulbar, E. D.; Gîrgel, I.; Lewins, C. J.; Edwards, P. R.; Martin, R. W.; Šatka, A.; Allsopp, D. W. E.; Shields, P. A.

    2013-09-01

    The use of etched nanorods from a planar template as a growth scaffold for a highly regular GaN/InGaN/GaN core-shell structure is demonstrated. The recovery of m-plane non-polar facets from etched high-aspect-ratio GaN nanorods is studied with and without the introduction of a hydrogen silsesquioxane passivation layer at the bottom of the etched nanorod arrays. This layer successfully prevented c-plane growth between the nanorods, resulting in vertical nanorod sidewalls (˜89.8°) and a more regular height distribution than re-growth on unpassivated nanorods. The height variation on passivated nanorods is solely determined by the uniformity of nanorod diameter, which degrades with increased growth duration. Facet-dependent indium incorporation of GaN/InGaN/GaN core-shell layers regrown onto the etched nanorods is observed by high-resolution cathodoluminescence imaging. Sharp features corresponding to diffracted wave-guide modes in angle-resolved photoluminescence measurements are evidence of the uniformity of the full core-shell structure grown on ordered etched nanorods.

  20. The use of PEEK nanorod arrays for the fabrication of nanoporous surfaces under high temperature: SiNx example.

    PubMed

    Martín, Jaime; Martín-González, Marisol

    2012-09-21

    Large area silicon nitride (SiN(x)) nanoporous surfaces are fabricated using poly(ether-ether-ketone) (PEEK) nanorod arrays as a template. The procedure involves manipulation of nanoporous anodic aluminum oxide (AAO) templates in order to form an ordered array of PEEK nanopillars with high temperature resistant characteristics. In this context, self-ordered AAO templates are infiltrated with PEEK melts via the "precursor film" method. Once the melts have been crystallized in the porous structure of AAO, the basis alumina layer is removed, yielding an ordered array of PEEK nanopillars. The resulting structure is a high temperature and chemical resistant polymeric nanomold, which can be utilized in the synthesis of nanoporous materials under aggressive conditions. Such conditions are high temperatures (up to 320 °C), vacuum, or extreme pH. For example, SiN(x) nanopore arrays have been grown by plasma enhanced chemical vapor deposition at 300 °C, which can be of interest as mold for nanoimprint lithography, due to its hardness and low surface energy. The SiN(x) nanopore array portrays the same characteristics as the original AAO template: 120 nm diameter pores and an interpore distance of 430 nm. Furthermore, the aspect ratio of the SiN(x) nanopores can be tuned by selecting an AAO template with appropriate conditions. The use of PEEK as a nanotemplate extends the applicability of polymeric nanopatterns into a temperature regime up to now not accessible and opens up the simple fabrication of novel nanoporous inorganic surfaces. PMID:22854871

  1. Stochastic memristive nature in Co-doped CeO{sub 2} nanorod arrays

    SciTech Connect

    Younis, Adnan; Chu, Dewei Li, Sean

    2013-12-16

    In this Letter, bipolar resistive switching characteristics of electrochemically deposited pure and Cobalt doped CeO{sub 2} nanorods architectures were reported. A conducting filament based model to address resistive switching process in these devices was proposed. Furthermore, the randomness in individual switching events and the prediction of switching probabilities were studied by imposing weak programming conditions. The present study offers insights into scrutinize the inherent stochastic nature in resistive switching characteristics within these devices rather than stressfully achieve high switching probabilities using excess voltage or time.

  2. Strong coupling in molecular exciton-plasmon Au nanorod array systems

    NASA Astrophysics Data System (ADS)

    Fedele, Stefano; Hakami, Manal; Murphy, Antony; Pollard, Robert; Rice, James

    2016-02-01

    We demonstrate here a strong coupling between localized surface plasmon modes in self-standing nanorods with excitons in a molecular J-aggregate layer through angular tuning. The enhanced exciton-plasmon coupling creates a Fano like line shape in the differential reflection spectra associated with the formation of hybrid states, leading to anti-crossing of the upper and lower polaritons with a Rabi frequency of 125 meV. The recreation of a Fano like line shape was found in photoluminescence demonstrating changes in the emission spectral profile under strong coupling.

  3. A novel electrochemiluminescent immunosensor based on CdS-coated ZnO nanorod arrays for HepG2 cell detection

    NASA Astrophysics Data System (ADS)

    Liu, Danqing; Wang, Lei; Ma, Shenghua; Jiang, Zhaohua; Yang, Bin; Han, Xiaojun; Liu, Shaoqin

    2015-02-01

    In this work, the highly oriented CdS-coated-ZnO nanorod arrays have been fabricated. The CdS-coated-ZnO nanorod arrays show high electrochemiluminescence intensity, fast response and good stability. All of the desirable properties spur the development of an ECL immunosensor for the detection of the liver cancer cell line (HepG2 cells). Two successive modification steps of 3-aminopropyltriethoxysilane and gold nanoparticles onto the CdS-coated-ZnO nanorod arrays not only offer the substrates for conjugation of antibody, but also effectively enhance the ECL signal, resulting in production of the high performance ECL immunosensor. The ECL immunosensor exhibits a sensitive response to HepG2 cells in a linear range of 300-10 000 cells mL-1 with a detection limit of 256 cells mL-1. The proposed sensor characteristics of high specificity, good reproducibility and remarkable stability will provide a sensitive, selective, and convenient approach for the clinical detection of cancer cells.In this work, the highly oriented CdS-coated-ZnO nanorod arrays have been fabricated. The CdS-coated-ZnO nanorod arrays show high electrochemiluminescence intensity, fast response and good stability. All of the desirable properties spur the development of an ECL immunosensor for the detection of the liver cancer cell line (HepG2 cells). Two successive modification steps of 3-aminopropyltriethoxysilane and gold nanoparticles onto the CdS-coated-ZnO nanorod arrays not only offer the substrates for conjugation of antibody, but also effectively enhance the ECL signal, resulting in production of the high performance ECL immunosensor. The ECL immunosensor exhibits a sensitive response to HepG2 cells in a linear range of 300-10 000 cells mL-1 with a detection limit of 256 cells mL-1. The proposed sensor characteristics of high specificity, good reproducibility and remarkable stability will provide a sensitive, selective, and convenient approach for the clinical detection of cancer cells

  4. Large-scale fabrication of polymer/Ag core-shell nanorod array as flexible SERS substrate by combining direct nanoimprint and electroless deposition

    NASA Astrophysics Data System (ADS)

    Liu, Sisi; Xu, Zhimou; Sun, Tangyou; Zhao, Wenning; Wu, Xinghui; Ma, Zhichao; Xu, Haifeng; He, Jian; Chen, Cunhua

    2014-06-01

    We demonstrate a highly sensitive surface-enhanced Raman scattering (SERS) substrate, which consists of Ag nanoparticles (NPs) assembled on the surface of a nanopatterned polymer film. The fabrication route of a polymer/Ag core-shell nanorod (PACSN) array employed a direct nanoimprint technique to create a high-resolution polymer nanorod array. The obtained nanopatterned polymer film was subjected to electroless deposition to form a sea-cucumber-like Ag shell over the surface of the polymer nanorod. The morphology and structures of PACSNs were analyzed by using scanning electron microscopy and X-ray diffraction. The as-synthesized PACSNs exhibited a remarkable SERS activity and Raman signal reproducibility to rhodamine 6G, and a concentration down to 10-12 M can be identified. The effect of electroless deposition time of Ag NPs onto the polymer nanorod surface was investigated. It was found that the electroless deposition time played an important role in SERS activity. Our results revealed that the combination of direct nanoimprint and electroless deposition provided a convenient and cost-effective way for large-scale fabrication of reliable SERS substrates without the requirement of expensive instruments.

  5. 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.

  6. Vertical La0.7Ca0.3MnO3 nanorods tailored by high magnetic field assisted pulsed laser deposition

    PubMed Central

    Zhang, Kejun; Dai, Jianming; Zhu, Xuebin; Zhu, Xiaoguang; Zuo, Xuzhong; Zhang, Peng; Hu, Ling; Lu, Wenjian; Song, Wenhai; Sheng, Zhigao; Wu, Wenbin; Sun, Yuping; Du, Youwei

    2016-01-01

    La0.7Ca0.3MnO3 (LCMO) thin films on (LaAlO3)0.3(Sr2AlTaO6)0.7 (001) [LSAT (001)] single crystal substrates have been prepared by high magnetic field assisted pulsed laser deposition (HMF-PLD) developed by ourselves. Uniformly sized and vertically aligned nanorod structures can be obtained under an applied high magnetic field above 5 T, and the dimension size of the nanorods can be manipulated by varying the applied magnetic field. It is found that the magnetic anisotropy is strongly correlated to the dimension size of the nanorods. A significantly enhanced low-field magnetoresistance (LFMR) of −36% under 0.5 T at 100 K can be obtained due to the enhanced carrier scattering at the vertical grain boundaries between the nanorods for the LCMO films. The growth mechanism of the nanorods has been also discussed, which can be attributed to the variation of deposition rate, adatom surface diffusion, and nucleation induced by the application of a high magnetic field in the film processing. The successful achievements of such vertical nanorod structures will provide an instructive route to investigate the physical nature of these nanostructures and achieve nanodevice manipulation. PMID:26778474

  7. Vertical La0.7Ca0.3MnO3 nanorods tailored by high magnetic field assisted pulsed laser deposition.

    PubMed

    Zhang, Kejun; Dai, Jianming; Zhu, Xuebin; Zhu, Xiaoguang; Zuo, Xuzhong; Zhang, Peng; Hu, Ling; Lu, Wenjian; Song, Wenhai; Sheng, Zhigao; Wu, Wenbin; Sun, Yuping; Du, Youwei

    2016-01-01

    La0.7Ca0.3MnO3 (LCMO) thin films on (LaAlO3)0.3(Sr2AlTaO6)0.7 (001) [LSAT (001)] single crystal substrates have been prepared by high magnetic field assisted pulsed laser deposition (HMF-PLD) developed by ourselves. Uniformly sized and vertically aligned nanorod structures can be obtained under an applied high magnetic field above 5 T, and the dimension size of the nanorods can be manipulated by varying the applied magnetic field. It is found that the magnetic anisotropy is strongly correlated to the dimension size of the nanorods. A significantly enhanced low-field magnetoresistance (LFMR) of -36% under 0.5 T at 100 K can be obtained due to the enhanced carrier scattering at the vertical grain boundaries between the nanorods for the LCMO films. The growth mechanism of the nanorods has been also discussed, which can be attributed to the variation of deposition rate, adatom surface diffusion, and nucleation induced by the application of a high magnetic field in the film processing. The successful achievements of such vertical nanorod structures will provide an instructive route to investigate the physical nature of these nanostructures and achieve nanodevice manipulation. PMID:26778474

  8. Vertical La0.7Ca0.3MnO3 nanorods tailored by high magnetic field assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Kejun; Dai, Jianming; Zhu, Xuebin; Zhu, Xiaoguang; Zuo, Xuzhong; Zhang, Peng; Hu, Ling; Lu, Wenjian; Song, Wenhai; Sheng, Zhigao; Wu, Wenbin; Sun, Yuping; Du, Youwei

    2016-01-01

    La0.7Ca0.3MnO3 (LCMO) thin films on (LaAlO3)0.3(Sr2AlTaO6)0.7 (001) [LSAT (001)] single crystal substrates have been prepared by high magnetic field assisted pulsed laser deposition (HMF-PLD) developed by ourselves. Uniformly sized and vertically aligned nanorod structures can be obtained under an applied high magnetic field above 5 T, and the dimension size of the nanorods can be manipulated by varying the applied magnetic field. It is found that the magnetic anisotropy is strongly correlated to the dimension size of the nanorods. A significantly enhanced low-field magnetoresistance (LFMR) of -36% under 0.5 T at 100 K can be obtained due to the enhanced carrier scattering at the vertical grain boundaries between the nanorods for the LCMO films. The growth mechanism of the nanorods has been also discussed, which can be attributed to the variation of deposition rate, adatom surface diffusion, and nucleation induced by the application of a high magnetic field in the film processing. The successful achievements of such vertical nanorod structures will provide an instructive route to investigate the physical nature of these nanostructures and achieve nanodevice manipulation.

  9. Broadband and wide angle light absorption for an aluminum nanorod array in a prism-coupling system

    NASA Astrophysics Data System (ADS)

    Jen, Yi-Jun; Dai, Jia-Wei; Chao, Jung-Hui

    2013-09-01

    Traditional optical thin films exhibit low absorption when light is incident obliquely because the optical path decreases with increasing angle of incidence [1]. A thin film absorber is also a challenge to perform high absorption at oblique incidence. Under the condition of total reflection, a thin metal film with thickness around 40nm in a Kretschmann configuration (prism / metal film / air) enables to absorb light at an extremely small angle range by exciting surface plasmon at the interface of metal/air [2]. In this work, a metamaterial thin film composed of aluminum nanorods is fabricated and used to absorb light in high efficiency. An aluminum nanorod array (Al NRA) deposited obliquely is arranged in a prism-coupling system to observed the reflection under the condition of total reflection of the system: BK7 prism/ Al NRA/ Air. The Al NRA is 184nm thick and tilted at an angle of 35° with respect to the surface normal. The deposition plane defined by the directions of rod and surface normal is orientated at angles of φ=0° and φ=180° with respect to the plane of incidence to measure the reflectance versus incident angles from 45° to 70° and wavelengths from 400nm to 700nm. The definition of the NRAs orientation is shown in Fig. 3. When the deposition plane is the same with the plane of incidence, the reflectance spectra indicate that the Al NRA exhibits strong absorptance over 80% at angles of incidence from 45° to 55° for both p-polarization and s-polarization. The enhanced p-polarized absorptance is extended from 45° to 70°. At φ=90°, the absorptance is weaker at angles of incidence from 55° to 70° compared with other two cases measured at φ=0° and φ=180°°.

  10. Branched zinc oxide nanorods arrays modified paper electrode for electrochemical immunosensing by combining biocatalytic precipitation reaction and competitive immunoassay mode.

    PubMed

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

    2015-12-15

    Branched zinc oxide nanorods (BZR) arrays, an array with high charge carries collection efficiency and specific surface area, are grown on the reduced graphene oxide-paper working electrode for the first time to construct a paper-based electrochemical (EC) immunosensor. Typically, the BZR are fabricated via a simple hydrothermal process, which can provide abundant sites for antibodies loading. By combining the large surface area of porous zinc oxide (PZS) and good biocompatibility of gold nanoparticles (AuNPs), PZS-AuNPs (PZS@Au) nanocomposites are designed to label horseradish peroxide (HRP) and antigens. After a competitive reaction between antigens and PZS@Au nanocomposites labeled antigens, the signal labels are introduced into the immunosensor, in which, HRP participate in biocatalytic precipitation process. The produced precipitate reduces the electrode surface area and hinders the electron transfer. With the increase of concentration of antigens, the signal labels introduced into the sensor decrease, thus, a signal-on immunoassay for α-fetoprotein detection is constructed. The proposed paper-based EC immunosensor combines enzymatic biocatalytic precipitation reaction and competitive immunoassay mode for the first time, and possesses a wide linear range from 0.2 pg mL(-1) to 500 ng mL(-1) with a detection limit of 0.08 pg mL(-1). In addition, the proposed method is simple, sensitive and specific and can be a promising platform for other protein detection. PMID:26232677

  11. A significant cathodic shift in the onset potential and enhanced photoelectrochemical water splitting using Au nanoparticles decorated WO3 nanorod array.

    PubMed

    Xu, Fang; Yao, Yanwen; Bai, Dandan; Xu, Ruishu; Mei, Jingjing; Wu, Dapeng; Gao, Zhiyong; Jiang, Kai

    2015-11-15

    Au nanoparticles decorated WO3 nanorod array was prepared and applied for solar water oxidation. Scanning electron microscopy and transmission electron microscop images showed that Au distributed on the surface of WO3 nanorod array. The surface plasmon resonance effect of Au nanoparticles contributed to the enhancement of photoelectrochemical performance of Au-WO3 photoanode, such as enhanced photocurrent density of 1.17mA/cm(2) at 1.0V vs Ag/AgCl, a cathodic shift of onset of ∼0.2V and higher stability. UV-vis absorption, electrochemical impedance and Mott-Schottky measurements proved that Au-WO3 photoanode has enhanced light absorption, lower transfer resistance, increased photogenerated carriers density and higher hole injection yield. Therefore, Au-WO3 photoanode exhibited higher photoelectrochemical performance than WO3 photoanode. PMID:26218199

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  13. Tailoring the morphology of carbon nanotube arrays: from spinnable forests to undulating foams.

    PubMed

    Zhang, Yingying; Zou, Guifu; Doorn, Stephen K; Htoon, Han; Stan, Liliana; Hawley, Marilyn E; Sheehan, Chris J; Zhu, Yuntian; Jia, Quanxi

    2009-08-25

    Directly spinning carbon nanotube (CNT) fibers from vertically aligned CNT arrays is a promising way for the application of CNTs in the field of high-performance materials. However, most of the reported CNT arrays are not spinnable. In this work, by controlling catalyst pretreatment conditions, we demonstrate that the degree of spinnability of CNTs is closely related to the morphology of CNT arrays. Shortest catalyst pretreatment time led to CNT arrays with the best spinnability, while prolonged pretreatment resulted in coarsening of catalyst particles and nonspinnable CNTs. By controlling the coalescence of catalyst particles, we further demonstrate the growth of undulating CNT arrays with uniform and tunable waviness. The CNT arrays can be tuned from well-aligned, spinnable forests to uniformly wavy, foam-like films. To the best of our knowledge, this is the first systematical study on the correlation between catalyst pretreatment, CNT morphology, and CNT spinnability. PMID:19640000

  14. Highly ordered Pb(Zr₀.₅₂ Ti₀.₄₈)O₃ piezoelectric nanorod arrays.

    PubMed

    Yang, Su Chul; Sanghadasa, Mohan; Priya, Shashank

    2013-06-01

    One-dimensional (1D) piezoelectric nanostructures have attracted significant attention for a broad range of applications including optoelectronics, thermoelectrics, electrochemical and electromechanical converters. We demonstrate the synthesis of 1D nanostructures based upon Pb(Zr0.52Ti0.48)O3 (PZT) on conductive substrates via sol-gel template synthesis. The vertically aligned PZT nanostructures with heights around one micron were synthesized by vacuum infiltration of sol-gel precursors into highly ordered cylindrical pores of anodized aluminum oxide templates. The 1D nanostructures were developed on large scale platinized silicon wafers and exhibited dense rod-like structure with a uniform diameter of 90 nm and an aspect ratio of 10. Scanning probe microscopy conducted on individual nanorods demonstrated good electromechanical properties with a high piezoelectric magnitude of 41 pm V(-1). We believe that this study opens the possibility of developing high performance nanoscale piezoelectric sensors and transducers. PMID:23637024

  15. Transparent, 3-dimensional light-collected, and flexible fiber-type dye-sensitized solar cells based on highly ordered hierarchical anatase TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Liang, Jia; Zhang, Gengmin; Yin, Jianbo; Yang, Yingchao

    2014-12-01

    Two kinds of hierarchical anatase TiO2 structures are synthesized by a facile hydrothermal method in this report. A new transparent, 3D light-collected, and flexible fiber-type dye-sensitized solar cell (FF-DSSC) with such hierarchical TiO2 structures is developed. The conversion efficiency of the FF-DSSC based on a TiCl4-treated TiO2 nanorod array (hierarchical structure I) exhibits about 4 times higher than that based on a HCl-treated TiO2 nanorod array, and further rises to 4.4% when the TiCl4-treated TiO2 nanorod array is treated in a mixed solution of (NH4)2TiF6 and H3BO3 three times (hierarchical structure II). The obvious enhancement in conversion efficiency can be ascribed to the dye adsorption promotion benefiting from their hierarchical structures. Beyond the attractive conversion efficiency, the new designed FF-DSSC possesses several advantages including good flexibility, excellent stability, and 3D light-collection. The conversion efficiencies of the FF-DSSCs can still keep 85%-90% even the FF-DSSCs are bent for 1000 times. The maximum power outputs of the FF-DSSCs characterized by Diffuse Illumination Mode using home-made Al reflector exhibit about 3 times higher than that done by Standard Illumination Mode due to 3D light-collections. The FF-DSSCs based on highly ordered hierarchical anatase TiO2 nanorod arrays hold great promise in future energy harvest.

  16. Improving photoelectrochemical performance by building Fe{sub 2}O{sub 3} heterostructure on TiO{sub 2} nanorod arrays

    SciTech Connect

    Cao, Chunlan; Hu, Chenguo; Shen, Weidong; Wang, Shuxia; Song, Sihong; Wang, Mingjun

    2015-10-15

    Highlights: • Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure was fabricated by two-step method. • The photoelectrochemical properties were studied upon visible light irradiation. • Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure shows superior photoelectrochemical property. • A possible mechanism for enhanced photoelectrochemical property was put forward. - Abstract: Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure nanorod arrays were synthesized on a fluorine-doped tin oxide conductive (FTO) glass substrate via two-step method for improving photoelectrochemical activity of TiO{sub 2}. The TiO{sub 2} nanorod arrays on FTO substrate were first prepared by hydrothermal method and then Fe{sub 2}O{sub 3} nanoparticles were coated onto the surface of TiO{sub 2} nanorod arrays through chemical bath deposition. The heterojunction yielded a photocurrent density of 39.75 μA cm{sup −2} at a bias potential of 0 V (vs. Ag/AgCl) under visible light irradiation, which is 2.2 times as much as that produced by the pure TiO{sub 2} nanorod arrays. The enhanced photoelectrochemical activity is attributed to the extension of the light response range and efficient separation of photogenerated carriers. Our results have demonstrated the advantage of the novel Fe{sub 2}O{sub 3}@TiO{sub 2} heterojunction and will provide a new path to the fabrication of heterostructural materials.

  17. Electrochromic properties of large-area and high-density arrays of transparent one-dimensional β-Ta2O5 nanorods on indium-tin-oxide thin-films

    NASA Astrophysics Data System (ADS)

    Devan, Rupesh S.; Gao, Shun-Yu; Ho, Wei-Der; Lin, Jin-Han; Ma, Yuan-Ron; Patil, Pramod S.; Liou, Yung

    2011-03-01

    We report on the synthesis, crystalline structure, and electrochromic properties of transparent one-dimensional (1D) orthorhombic (β) Ta2O5 nanorods grown in a large-area high-density array. The transparent 1D β-Ta2O5 nanorod array was synthesized on a conducting indium-tin-oxide thin-film via hot-filament metal-oxide vapor deposition. The array contained ˜1900 β-Ta2O5 nanorods per square micrometer, which were on average, ˜17 nm wide and ˜300 nm long. The good coloration/bleaching cycles, large ion-diffusion coefficient (˜2.35×10-8 cm2/s), and high reversibility (˜79.8%) demonstrate that the 1D β-Ta2O5 nanorods to be a potential electrochromic material for electrochromic devices or smart windows.

  18. Facile construction of vertically aligned EuS-ZnO hybrid core shell nanorod arrays for visible light driven photocatalytic properties

    SciTech Connect

    Ranjith, K. S.; Kumar, D. Ranjith; Kumar, R. T. Rajendra

    2015-06-24

    We demonstrated the development of coupled semiconductor in the form of hybrid heterostructures for significant advancement in catalytic functional materials. In this article, we report the preparation of vertically aligned core shell ZnO-EuS nanorod photocatalyst arrays by a simple chemical solution process followed by sulfudation process. The XRD pattern confirmed formation of the hexagonal wurtzite structure of ZnO and cubic nature of the EuS. Cross sectional FESEM images show vertical rod array structure, and the size of the nanorods ranges from 80 to 120 nm. UV-Vis DRS spectra showed that the optical absorption of ZnO was significantly enhanced to the visible region by modification with EuS surfaces. TEM study confirmed that the surface of ZnO was drastically improved by the modification with EuS nanoparticle. The catalytic activity of EuS−ZnO core shell nanorod arrays were evaluated by the photodegradation of Methylene Blue (MB) dye under visible irradiation. The results revealed that the photocatalytic activity of EuS−ZnO was much higher than that of ZnO under natural sunlight. EuS−ZnO was found to be stable and reusable without appreciable loss of catalytic activity up to four consecutive cycles.

  19. Annealing effect on the photoluminescence properties of ZnO nanorod array prepared by a PLD-assistant wet chemical method

    SciTech Connect

    Wei Sufeng; Lian Jianshe; Wu Hua

    2010-11-15

    Well-aligned ZnO nanorod arrays were synthesized by a wet chemical method on the glass substrate with ZnO thin film as seed layer prepared by pulsed laser deposition. The effect of annealing temperature on the luminescence characteristics was investigated. As the annealing temperature increased, the photoluminescence properties show a general enhancing tendency. The nanorod array with high ultraviolet emission and negligible visible light emission (designated by the photoluminescence intensity ratio of ultraviolet to visible emission of 66.4) is obtained by annealing the sample at 700 deg. C for 1 h. Based on the results of X-ray photoelectron spectroscopy and photoluminescence spectra, the mechanisms of visible emission were discussed. - Research Highlights: {yields} ZnO nanorod array with good crystallography, low defects concentration and good optical property was obtained after annealed at 700 deg. C for 1 h. {yields} The transition from the conduction band to the O{sub i} level may be responsible for the yellow-green emission. {yields} The yellow emission may originate from the presence of Zn(OH){sub 2} on the surface or the band transition from conduction band to V{sub o}Zn{sub i} level. {yields} The transition from the Zn{sub i} level to the level should produce an orange emission or an orange-red emission.

  20. Flexible coaxial-type fiber solid-state asymmetrical supercapacitor based on Ni3S2 nanorod array and pen ink electrodes

    NASA Astrophysics Data System (ADS)

    Wen, Jian; Li, Songzhan; Zhou, Kai; Song, Zengcai; Li, Borui; Chen, Zhao; Chen, Tian; Guo, Yaxiong; Fang, Guojia

    2016-08-01

    Fiber supercapacitors have attracted public attentions because of their merits of relatively high capacitance density, flexibility and easy integration with various electronic devices. In this work, a flexible coaxial-type fiber solid-state asymmetrical supercapacitor (ASC) based on Ni3S2 nanorod array electrode and pen ink electrode was successfully fabricated. The Ni3S2 nanorod array electrode was synthesized by directly growing Ni3S2 nanorod arrays on a nickel wire through a facile hydrothermal method and the pen ink electrode as negative electrode was synthesized by a simple dip-coating method. The solid-state ASC device presents a stable voltage window of 1.4 V and behaves a high specific capacitance of 34.9 F g-1 (87.25 F cm-1) at a scan rate of 10 mV s-1. Compared with the symmetric supercapacitor (SSC) based on Ni3S2 electrodes, the ASC device provide an increased energy density of 8.2 Wh kg-1 (0.81 mWh cm-3) at the power density of 214.6 W kg-1 (21.12 mW cm-3). In addition, the ASC device also exhibits excellent electrochemical stability with 93.1% of initial specific capacitance after 3000 consecutive cycles and good mechanical stability. These encouraging results present its great potential in flexible solid-state energy storage devices.

  1. A Way of Tailoring Magnetic Anisotropy of Co Nanowire Arrays: Magnetic Field Annealing.

    PubMed

    Ren, Yong; Qu, Li; Fan, Jiangxia; Dai, Bo; Wang, Jianbo

    2015-06-01

    Hexagonal close-packed Co nanowire arrays in anodic aluminum oxide template with the diameter of 50 nm have been fabricated using an ac electrodeposition method. The effect of magnetic field annealing on the thermal stability and magnetic properties of these nanwire arrays was studied. XRD measurements indicate the increase of diffraction intensity with the increase of heat-treatment temperature without magnetic field. Furthermore, the intensity of diffraction peak decreases rapidly if the sample undergoes the magnetic field annealing. Influence of different annealing process on the magnetic properties of Co nanowire arrays has also been studied. It is found that the magnetocrystalline anisotropy of hcp Co becomes weaker after magnetic field annealing, which lead to increase of the total anisotropy of Co nanowire arrays. PMID:26369071

  2. TiO2 nanorod arrays functionalized with In2S3 shell layer by a low-cost route for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Gan, Xiaoyan; Li, Xiaomin; Gao, Xiangdong; Qiu, Jijun; Zhuge, Fuwei

    2011-07-01

    We report the fabrication and characterization of a TiO2-In2S3 core-shell nanorod array structure for application of semiconductor-sensitized solar cells. Hydrothermally synthesized TiO2 nanorod arrays on FTO glass substrates are functionalized with a uniform In2S3 shell layer by using the successive ion layer adsorption and reaction (SILAR) method. This low-cost technique promotes a uniform deposition of In2S3 nanoshells on the surface of TiO2 nanorods, thus forming an intact interface between the In2S3 shell and TiO2 core. Results show that the thickness of In2S3 shell layers as well as the visible light absorption threshold can be effectively controlled by varying the coating cycles during the SILAR process. The best reproducible performance of the sandwich solar cell using the TiO2-In2S3 core-shell nanorod arrays as photoelectrodes was obtained after 30 SILAR cycles, exhibiting a short-circuit current (Isc) of 2.40 mA cm - 2, an open-circuit voltage (Voc) of 0.56 V, a fill factor (ff) of 0.40 and a conversion efficiency (η) of 0.54%, respectively. These results demonstrate a feasible and controllable route towards In2S3 coating on a highly structured substrate and a proof of concept that such TiO2-In2S3 core-shell architectures are novel and promising photoelectrodes in nanostructured solar cells.

  3. Dense arrays of cobalt nanorods as rare-earth free permanent magnets.

    PubMed

    Anagnostopoulou, E; Grindi, B; Lacroix, L-M; Ott, F; Panagiotopoulos, I; Viau, G

    2016-02-11

    We demonstrate in this paper the feasibility to elaborate rare-earth free permanent magnets based on cobalt nanorods assemblies with energy product (BH)max exceeding 150 kJ m(-3). The cobalt rods were prepared by the polyol process and assembled from wet suspensions under a magnetic field. Magnetization loops of dense assemblies with remanence to a saturation of 0.99 and squareness of 0.96 were measured. The almost perfect M(H) loop squareness together with electron microscopy and small angle neutron scattering demonstrate the excellent alignment of the rods within the assemblies. The magnetic volume fraction was carefully measured by coupling magnetic and thermogravimetric analysis and found in the range from 45 to 55%, depending on the rod diameter and the alignment procedure. This allowed a quantitative assessment of the (BH)max values. The highest (BH)max of 165 kJ m(-3) was obtained for a sample combining a high magnetic volume fraction and a very large M(H) loop squareness. This study shows that this bottom-up approach is very promising to get new hard magnetic materials that can compete in the permanent magnet panorama and fill the gap between the ferrites and the NdFeB magnets. PMID:26817959

  4. Impurity induced crystallinity and optical emissions in ZnO nanorod arrays

    NASA Astrophysics Data System (ADS)

    Panda, N. R.; Acharya, B. S.

    2015-01-01

    We report the growth of ZnO nanocrystallites doped with impurities such as B, N and S by green chemistry route using ultrasound. The effect of intrinsic defects and impurity doping on the structural and optical properties of ZnO nanostructures has been studied and discussed. Characterization studies carried out using x-ray diffraction (XRD) reveal the change in lattice parameters and crystallinity of ZnO in the presence of dopant. This has been explained on the basis of the dopant substitution at regular anion and interstitial sites. Study on surface morphology by field emission scanning electron microscopy (FESEM) shows a change from particle-like structure to aligned nanorods nucleated at definite sites. Elemental analysis such as x-ray photon electron spectroscopy (XPS) has been carried out to ascertain the dopant configuration in ZnO. This has been corroborated by the results obtained from FTIR and Raman studies. UV-vis light absorption and PL studies show an expansion of the band gap which has been explained on the basis of Moss-Burstein shift in the electronic band gap of ZnO by impurity incorporation. The optical emissions corresponding to excitonic transition and defect centres present in the band gap of ZnO is found to shift towards lower/higher wavelength sides. New PL bands observed have been assigned to the transitions related to the impurity states present in the band gap of ZnO along with intrinsic defects.

  5. Magnetic field dependent small-angle neutron scattering on a Co nanorod array: evidence for intraparticle spin misalignment

    PubMed Central

    Günther, A.; Bick, J.-P.; Szary, P.; Honecker, D.; Dewhurst, C. D.; Keiderling, U.; Feoktystov, A. V.; Tschöpe, A.; Birringer, R.; Michels, A.

    2014-01-01

    The structural and magnetic properties of a cobalt nanorod array have been studied by means of magnetic field dependent small-angle neutron scattering (SANS). Measurement of the unpolarized SANS cross section dΣ/dΩ of the saturated sample in the two scattering geometries where the applied magnetic field H is either perpendicular or parallel to the wavevector k i of the incoming neutron beam allows one to separate nuclear from magnetic SANS, without employing the usual sector-averaging procedure. The analysis of the SANS data in the saturated state provides structural parameters (rod radius and centre-to-centre distance) that are in good agreement with results from electron microscopy. Between saturation and the coercive field, a strong field dependence of dΣ/dΩ is observed (in both geometries), which cannot be explained using the conventional expression of the magnetic SANS cross section of magnetic nanoparticles in a homogeneous nonmagnetic matrix. The origin of the strong field dependence of dΣ/dΩ is believed to be related to intradomain spin misalignment, due to magnetocrystalline and magnetoelastic anisotropies and magnetostatic stray fields. PMID:24904245

  6. Detection of Mycoplasma pneumoniae in Simulated and True Clinical Throat Swab Specimens by Nanorod Array-Surface-Enhanced Raman Spectroscopy

    PubMed Central

    Hennigan, Suzanne L.; Driskell, Jeremy D.; Dluhy, Richard A.; Zhao, Yiping; Tripp, Ralph A.; Waites, Ken B.; Krause, Duncan C.

    2010-01-01

    The prokaryote Mycoplasma pneumoniae is a major cause of respiratory disease in humans, accounting for 20% of all community-acquired pneumonia and the leading cause of pneumonia in older children and young adults. The limitations of existing options for mycoplasma diagnosis highlight a critical need for a new detection platform with high sensitivity, specificity, and expediency. Here we evaluated silver nanorod arrays (NA) as a biosensing platform for detection and differentiation of M. pneumoniae in culture and in spiked and true clinical throat swab samples by surface-enhanced Raman spectroscopy (SERS). Three M. pneumoniae strains were reproducibly differentiated by NA-SERS with 95%–100% specificity and 94–100% sensitivity, and with a lower detection limit exceeding standard PCR. Analysis of throat swab samples spiked with M. pneumoniae yielded detection in a complex, clinically relevant background with >90% accuracy and high sensitivity. In addition, NA-SERS correctly classified with >97% accuracy, ten true clinical throat swab samples previously established by real-time PCR and culture to be positive or negative for M. pneumoniae. Our findings suggest that the unique biochemical specificity of Raman spectroscopy, combined with reproducible spectral enhancement by silver NA, holds great promise as a superior platform for rapid and sensitive detection and identification of M. pneumoniae, with potential for point-of-care application. PMID:21049032

  7. Regularly patterned non-polar InGaN/GaN quantum-well nanorod light-emitting diode array.

    PubMed

    Tu, Charng-Gan; Liao, Che-Hao; Yao, Yu-Feng; Chen, Horng-Shyang; Lin, Chun-Han; Su, Chia-Ying; Shih, Pei-Ying; Chen, Wei-Han; Zhu, Erwin; Kiang, Yean-Woei; Yang, C C

    2014-12-15

    The growth and process of a regularly patterned nanorod (NR)- light-emitting diode (LED) array with its emission from sidewall non-polar quantum wells (QWs) are demonstrated. A pyramidal un-doped GaN structure is intentionally formed at the NR top for minimizing the current flow through this portion of the NR such that the injection current can be effectively guided to the sidewall m-plane InGaN/GaN QWs for emission excitation by a conformal transparent conductor (GaZnO). The injected current density at a given applied voltage of the NR LED device is similar to that of a planar c-plane or m-plane LED. The blue-shift trend of NR LED output spectrum with increasing injection current is caused by the non-uniform distributions of QW width and indium content along the height on a sidewall. The photoluminescence spectral shift under reversed bias confirms that the emission of the fabricated NR LED comes from non-polar QWs. PMID:25607494

  8. Fabrication and photoelectrochemical characteristics of In2S3 nano-flower films on TiO2 nanorods arrays

    NASA Astrophysics Data System (ADS)

    Han, Minmin; Yu, Limin; Chen, Wenyuan; Wang, Wenzhen; Jia, Junhong

    2016-04-01

    The In2S3 nano-flower films on TiO2/FTO (Fluorine-doped tin oxide) substrates were synthesized via hydrothermal method and the photoelectrochemical performances of In2S3/TiO2 photoelectrodes were characterized. The roles of PSS (poly(sodium-p-styrenesul-fonate)) and PEG (polyethylene glycol) on the structure controlling of In2S3 films were also discussed. The results show that the In2S3 nano-flower films consisted of ultrathin nanoflakes with a thickness of 5 nm are successfully grew on the surface of TiO2 nanorod arrays. PEG could play a role as the morphology-directing agent by confining crystal growth in certain directions, while PSS could provide coordination sites with long chains and lead to the formation of spherical structure. The energy conversion efficiency of In2S3 nano-flower/TiO2 photoelectrodes enhances thrice compared with that of bare TiO2 photoelectrode. This research presents further insight for improving the efficiency of semiconductors by using the suitable electron transfer channels, which may be promising for rational construction of solar conversion and storage devices.

  9. Tailored Height Gradients in Vertical Nanowire Arrays via Mechanical and Electronic Modulation of Metal-Assisted Chemical Etching.

    PubMed

    Otte, M A; Solis-Tinoco, V; Prieto, P; Borrisé, X; Lechuga, L M; González, M U; Sepulveda, B

    2015-09-01

    In current top-down nanofabrication methodologies the design freedom is generally constrained to the two lateral dimensions, and is only limited by the resolution of the employed nanolithographic technique. However, nanostructure height, which relies on certain mask-dependent material deposition or etching techniques, is usually uniform, and on-chip variation of this parameter is difficult and generally limited to very simple patterns. Herein, a novel nanofabrication methodology is presented, which enables the generation of high aspect-ratio nanostructure arrays with height gradients in arbitrary directions by a single and fast etching process. Based on metal-assisted chemical etching using a catalytic gold layer perforated with nanoholes, it is demonstrated how nanostructure arrays with directional height gradients can be accurately tailored by: (i) the control of the mass transport through the nanohole array, (ii) the mechanical properties of the perforated metal layer, and (iii) the conductive coupling to the surrounding gold film to accelerate the local electrochemical etching process. The proposed technique, enabling 20-fold on-chip variation of nanostructure height in a spatial range of a few micrometers, offers a new tool for the creation of novel types of nano-assemblies and metamaterials with interesting technological applications in fields such as nanophotonics, nanophononics, microfluidics or biomechanics. PMID:26033973

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

    PubMed

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

    2016-06-01

    Highly photoactive and durable photoanode materials are the key to photoelectrochemical water splitting. In this paper, hierarchically branched Fe2O3@TiO2 nanorod arrays (denoted as Fe2O3@TiO2 BNRs) composed of a long Fe2O3 trunk and numerous short TiO2 nanorod branches were fabricated and used as photoanodes for water splitting. Significant improvement of photoelectrochemical water splitting performance was observed based on Fe2O3@TiO2 BNRs. The photocurrent density of Fe2O3@TiO2 BNRs reaches up to 1.3 mA cm(-2) at 1.23 V versus RHE, which is 10 times higher than that of pristine Fe2O3 nanorod arrays under the same conditions. Furthermore, an obvious cathodic shift in the onset potential of photocurrent was observed in the Fe2O3@TiO2 BNRs. More significantly, the Fe2O3@TiO2 BNRs are quite stable even after 3600 s continuous illumination, and the photocurrent density shows almost no decay. Finally, a tentative mechanism was proposed to explain the superior performance of Fe2O3@TiO2 BNRs for PEC water splitting and discussed in detail on the basis of our experimental results. PMID:27189633

  11. CdS and CdS/CdSe sensitized ZnO nanorod array solar cells prepared by a solution ions exchange process

    SciTech Connect

    Chen, Ling; Gong, Haibo; Zheng, Xiaopeng; Zhu, Min; Zhang, Jun; Yang, Shikuan; Cao, Bingqiang

    2013-10-15

    Graphical abstract: - Highlights: • CdS and CdS/CdSe quantum dots are assembled on ZnO nanorods by ion exchange process. • The CdS/CdSe sensitization of ZnO effectively extends the absorption spectrum. • The performance of ZnO/CdS/CdSe cell is improved by extending absorption spectrum. - Abstract: In this paper, cadmium sulfide (CdS) and cadmium sulfide/cadmium selenide (CdS/CdSe) quantum dots (QDs) are assembled onto ZnO nanorod arrays by a solution ion exchange process for QD-sensitized solar cell application. The morphology, composition and absorption properties of different photoanodes were characterized with scanning electron microscope, transmission electron microscope, energy-dispersive X-ray spectrum and Raman spectrum in detail. It is shown that conformal and uniform CdS and CdS/CdSe shells can grow on ZnO nanorod cores. Quantum dot sensitized solar cells based on ZnO/CdS and ZnO/CdS/CdSe nanocable arrays were assembled with gold counter electrode and polysulfide electrolyte solution. The CdS/CdSe sensitization of ZnO can effectively extend the absorption spectrum up to 650 nm, which has a remarkable impact on the performance of a photovoltaic device by extending the absorption spectrum. Preliminary results show one fourth improvement in solar cell efficiency.

  12. Synergistic Effect of Surface Plasmonic particles and Surface Passivation layer on ZnO Nanorods Array for Improved Photoelectrochemical Water Splitting

    NASA Astrophysics Data System (ADS)

    Liu, Yichong; Yan, Xiaoqin; Kang, Zhuo; Li, Yong; Shen, Yanwei; Sun, Yihui; Wang, Li; Zhang, Yue

    2016-07-01

    One-dimensional zinc oxide nanorods array exhibit excellent electron mobility and thus hold great potential as photoanode for photoelelctrochemical water splitting. However, the poor absorption of visible light and the prominent surface recombination hider the performance improvement. In this work, Au nanoparticles and aluminium oxide were deposited onto the surface of ZnO nanorods to improve the PEC performance. The localized surface plasmon resonance of Au NPs could expand the absorption spectrum to visible region. Simultaneously, the surface of passivation with Au NPs and Al2O3 largely suppressed the photogenerated electron-hole recombination. As a result, the optimal solar-to-hydrogen efficiency of ZnO/Au/Al2O3 with 5 cycles was 6.7 times that of pristine ZnO, ascribed to the synergistic effect of SPR and surface passivation. This research reveals that the synergistic effect could be used as an important method to design efficient photoanodes for photoelectrochemical devices.

  13. Specificity and Strain-Typing Capabilities of Nanorod Array-Surface Enhanced Raman Spectroscopy for Mycoplasma pneumoniae Detection

    PubMed Central

    Henderson, Kelley C.; Benitez, Alvaro J.; Ratliff, Amy E.; Crabb, Donna M.; Sheppard, Edward S.; Winchell, Jonas M.; Dluhy, Richard A.; Waites, Ken B.; Atkinson, T. Prescott; Krause, Duncan C.

    2015-01-01

    Mycoplasma pneumoniae is a cell wall-less bacterial pathogen of the human respiratory tract that accounts for > 20% of all community-acquired pneumonia (CAP). At present the most effective means for detection and strain-typing is quantitative polymerase chain reaction (qPCR), which can exhibit excellent sensitivity and specificity but requires separate tests for detection and genotyping, lacks standardization between available tests and between labs, and has limited practicality for widespread, point-of-care use. We have developed and previously described a silver nanorod array-surface enhanced Raman Spectroscopy (NA-SERS) biosensing platform capable of detecting M. pneumoniae with statistically significant specificity and sensitivity in simulated and true clinical throat swab samples, and the ability to distinguish between reference strains of the two main genotypes of M. pneumoniae. Furthermore, we have established a qualitative lower endpoint of detection for NA-SERS of < 1 genome equivalent (cell/μl) and a quantitative multivariate detection limit of 5.3 ± 1 cells/μl. Here we demonstrate using partial least squares- discriminatory analysis (PLS-DA) of sample spectra that NA-SERS correctly identified M. pneumoniae clinical isolates from globally diverse origins and distinguished these from a panel of 12 other human commensal and pathogenic mycoplasma species with 100% cross-validated statistical accuracy. Furthermore, PLS-DA correctly classified by strain type all 30 clinical isolates with 96% cross-validated accuracy for type 1 strains, 98% cross-validated accuracy for type 2 strains, and 90% cross-validated accuracy for type 2V strains. PMID:26121242

  14. Real-time monitoring of the solution growth of ZnO nanorods arrays by quartz microbalances and in-situ temperature sensors

    PubMed Central

    Orsini, Andrea; Falconi, Christian

    2014-01-01

    Wet-chemistry methods have crucial advantages for the synthesis of nanostructures, including simple, low-cost, large-area, and low-temperature deposition on almost arbitrary substrates. Nevertheless, the rational design of improved wet-chemistry procedures is extremely difficult because, in practice, only post-synthesis characterization is possible. In fact, the only methods for on-line monitoring the growth of nanostructures in liquids are complex, expensive and introduce intricate artifacts. Here we demonstrate that electro-mechanically resonating substrates and in-situ temperature sensors easily enable an accurate real-time investigation of reaction kinetics and, in combination with conventional SEM imaging, greatly facilitate the rational design of optimized synthesis procedures; in particular, such a simple approach provides useful insight for the development of processes where one or more key parameters are dynamically adjusted. As a proof-of-concept, first, we accurately characterize a process for fabricating arrays of ZnO nanorods; afterwards, we design a dynamic-temperature process that, in comparison with the corresponding constant-temperature procedure, is almost-ideally energy efficient and results in ZnO nanorods with improved characteristics in terms of length, aspect ratio, and total deposited nanorods mass. This is a major step towards the rational design of dynamic procedures for the solution growth of nanostructures. PMID:25190110

  15. TiO{sub 2} nanorods branched on fast-synthesized large clearance TiO{sub 2} nanotube arrays for dye-sensitized solar cells

    SciTech Connect

    Hu Anzheng; Li Haina; Jia Zhiyong; Xia Zhengcai

    2011-11-15

    A large clearance TiO{sub 2} nanotube arrays (LTAs) has been synthesized by a not more than 12 h anodization duration and based on this a branched TiO{sub 2} nanotube arrays (BLTs) has been achieved through TiO{sub 2} nanorods branch-like grown on the LTAs. Some key factors and probable mechanisms of the fabrication processes on two novel nanoarchitectures are discussed. Exhilaratingly, it is found that the obtained LTAs has demonstrated large pore diameter and void spaces (pore diameter {approx}350 nm; void spaces {approx}160 nm; and tube length {approx}3.5 {mu}m), and the synthesized hierarchical BLTs, compared with conventional TiO{sub 2} nanotube arrays, has shown a much stronger dye absorption performance and an approximately double of the solar cell efficiency (in our case from 1.62% to 3.18% under simulated AM 1.5 conditions). - Graphical Abstract: The schematic diagram of synthesis process for LTAs and BLTs is on the above and the corresponding FESEM images of obtained photoanodes samples are shown below. Highlights: > Large clearance TiO{sub 2} nanotube arrays (LTAs) was synthesized by a fast anodization process of 12 h. > Anodization time of 12 h is just 10% of about 120 h reported in the previous references. > Branch-like TiO{sub 2} nanotube arrays (BLTs) was achieved by growing TiO{sub 2} nanorods on the LTAs. > Obtained BLTs and LTAs show impressive morphology and noticeable improvement of surface area. > BLTs shows about more than 1 times higher solar cell efficiency than that of TiO{sub 2} nanotube arrays.

  16. Hierarchical three-dimensional branched hematite nanorod arrays with enhanced mid-visible light absorption for high-efficiency photoelectrochemical water splitting.

    PubMed

    Wang, Degao; Chang, Guoliang; Zhang, Yuying; Chao, Jie; Yang, Jianzhong; Su, Shao; Wang, Lihua; Fan, Chunhai; Wang, Lianhui

    2016-07-01

    Herein, we presented hierarchical three-dimensional (3D) branched hematite nanorod arrays (NAs) on transparent fluorine-doped tin oxide (FTO) conductive glass substrates, which exhibited high PEC water splitting performance due to the enhancement of mid-visible light harvesting as well as charge separation and transfer. The introduction of a TiO2 underlayer made the as-prepared 3D branched hematite NAs achieve a photocurrent density of 0.61 mA cm(-2) at 1.23 V vs. reversible hydrogen electrode (RHE) without high-temperature activation. PMID:27283270

  17. Tailoring the parameters of nanohole arrays in gold films for sensing applications.

    SciTech Connect

    McMahon, J. M.; Schatz, G. C.; Gray, S. K.; Northwestern Univ.

    2007-01-01

    Subwavelength hole arrays in metal films have the potential to exhibit narrow and high refractive index (RI) sensitive transmission features. We have previously demonstrated that such features can arise from the coupling between Wood anomalies (WAs) and surface Plasmon polaritons (SPPs) on opposite sides of the metal film, the 'WA-SPP' effect. Rigorous coupled-wave analysis (RCWA) calculations on a 2D model, which are shown to give WA-SPP features very similar to that of 3D Finite-Difference Time- Domain (FDTD) calculations, are performed to determine how system parameters influence the strength of the WA-SPP effect. Herein we show that the optimum values for the film thickness and hole diameter are 45 and 175 nm, respectively.

  18. Optimization of carbothermic synthesis of zinc-oxide micro- and nanorod arrays and their morphometric parameters

    NASA Astrophysics Data System (ADS)

    Lyanguzov, N. V.; Kaydashev, E. M.; Zakharchenko, I. N.; Bunina, O. A.

    2013-09-01

    The influence of argon-buffer pressure and distance from the material source on morphometric parameters of arrays of vertically aligned ZnO nano- and microrods was studied. The rods were grown by the carbothermic method on Si(100) substrates with a ZnO thin-film sublayer. Systematic studies of catalyst-free growth, as well as of the effect of growth catalysts Au and Cu on the rods' formation process and their sizes, were performed. It was found that a catalyst plays a role only on the initial stage and does not participate in the consequent rods' growth under the applied synthesis conditions. The possibility of controlling the average diameters, lengths, and densities of superficial distribution of the rods within the ranges of 100-300 nm, 1.5-9 μm, and (2.8-5.3) × 108 cm-2, respectively, was demonstrated.

  19. Tailor-made rylene arrays for high performance n-channel semiconductors.

    PubMed

    Jiang, Wei; Li, Yan; Wang, Zhaohui

    2014-10-21

    Rylene dyes, made up of naphthalene units linked in peri-positions, are emerging as promising key building blocks to create π-functional materials. Chemists have found uses for these ribbonlike structures in a wide range of applications of optoelectronic devices. Because their structure combines two sets of six-membered electron-withdrawing dicarboxylic imide rings, rylene diimides exhibit enhanced solubility, excellent chemical and thermal stabilities, high electron affinities, and remarkable electron-transporting properties. Among them, perylene diimide (PDI) and naphthalene diimide (NDI) derivatives are important representatives improving the performance of electron-transporting technologies, relative to their p-channel counterparts. Pioneering works by Müllen and Langhals have inspired chemists to extend the π-conjugation along the peri-positions of rylene diimides, which generally results in impressive bathochromic shifts and a nearly linear increase in the extinction coefficient. In addition, in the past years, researchers have focused on π-expansion of NDI or PDI systems through bay-functionalization with carbocyclic and heterocyclic rings annulated onto the skeleton. However, chemists have rarely investigated lateral expansion via both bay- and nonbay-functionalization to construct homologous series of rylene arrays with different electronic delocalization and fine-tuned flexible linkage. This is probably due to the lack of effective procedures for the (multi) carbon-carbon formation and annulation of electron-deficient rylene imide units. In this Account, we discuss our recent progress in the design and synthesis of laterally expanded rylene dyes based on homocoupling and cross-coupling reactions of core-functionalized PDIs and NDIs to achieve novel high performance n-channel organic semiconducting materials. These new achievements offer us opportunities to learn fundamental issues about how chemical and physical properties alter with incremental

  20. Technological Aspects in Fabrication of Micro- and Nano-Sized Carbon Based Features: Nanorods, Periodical Arrays and Self-Standing Membranes

    NASA Astrophysics Data System (ADS)

    Ižák, Tibor; Domonkos, Mária; Babchenko, Oleg; Varga, Marián; Rezek, Bohuslav; Jurka, Vlastimil; Hruška, Karel; Kromka, Alexander

    2015-09-01

    Diamond and/or carbon thin films are in the center of interest due to their variability and extraordinary combination of intrinsic properties. However, some applications require fabrication of films with tailored properties. Especially, fabrication of periodic structures is highly attractive due to their increased surface area. In this contribution we point out the key technological aspects for fabrication of micro- and nano-sized carbon-based structures. Three representative structures are presented: diamond nanorods, self-assembled templates and self-standing diamond membranes. We found that the diameter of diamond nanorods can be controlled in a broad range from 10 to 200 nm by the masking material (Au vs Ni) and its initial thickness (from few to tens of nanometers). The assembly of polystyrene microspheres in mono- or multi-layer with square or hexagonal periodicities was controlled by the spin-coating parameters. The diamond porous membrane was selectively grown on Si substrate with an interdigital or mesh like geometry. Advantages of each structure as well as the fabrication limitations are discussed more in detail and finally their representative applications are pointed out.

  1. Tailoring plasmonic properties of gold nanohole arrays for surface-enhanced Raman scattering.

    PubMed

    Zheng, Peng; Cushing, Scott K; Suri, Savan; Wu, Nianqiang

    2015-09-01

    The wide plasmonic tuning range of nanotriangle and nanohole array patterns fabricated by nanosphere lithography makes them promising in surface-enhanced Raman scattering (SERS) sensors. Unfortunately, it is challenging to optimize these patterns for SERS sensing because their optical response is a complex mixture of localized surface plasmon resonance (SPR) and propagating surface plasmon polariton (SPP). In this paper, transmission and reflection measurements are combined with finite difference time domain simulations to identify and separate each plasmonic mode, discerning which resonance leads to the electromagnetic field enhancement. The SERS enhancement is found to be dominated by the absorption, which is shifted from the transmission and reflection dips usually used as tuning points, and by the 'gap' defects formed within the pattern. These effects have different spectral and geometric dependences, forming two optimization curves which can be used to predict the best performance for a given excitation wavelength. The developed model is verified with experimental SERS measurements for several nanohole sizes and periodicities, and then used to give optimal fabrication parameters for a range of measurement conditions. The results will promote the application of two-dimensional plasmonic nanoarrays in SERS sensors. PMID:25586930

  2. Tailoring Anisotropic Interactions between Soft Nanospheres Using Dense Arrays of Smectic Liquid Crystal Edge Dislocations.

    PubMed

    Coursault, Delphine; Blach, Jean-Francois; Grand, Johan; Coati, Alessandro; Vlad, Alina; Zappone, Bruno; Babonneau, David; Lévi, Georges; Félidj, Nordin; Donnio, Bertrand; Gallani, Jean-Louis; Alba, Michel; Garreau, Yves; Borensztein, Yves; Goldmann, Michel; Lacaze, Emmanuelle

    2015-12-22

    We investigated composite films of gold nanoparticles (NPs)/liquid crystal (LC) defects as a model system to understand the key parameters, which allow for an accurate control of NP anisotropic self-assemblies using soft templates. We combined spectrophotometry, Raman spectroscopy, and grazing incidence small-angle X-ray scattering with calculations of dipole coupling models and soft sphere interactions. We demonstrate that dense arrays of elementary edge dislocations can strongly localize small NPs along the defect cores, resulting in formation of parallel chains of NPs. Furthermore, we show that within the dislocation cores the inter-NP distances can be tuned. This phenomenon appears to be driven by the competition between "soft (nano)sphere" attraction and LC-induced repulsion. We evidence two extreme regimes controlled by the solvent evaporation: (i) when the solvent evaporates abruptly, the spacing between neighboring NPs in the chains is dominated by van der Waals interactions between interdigitated capping ligands, leading to chains of close-packed NPs; (ii) when the solvent evaporates slowly, strong interdigitation between the is avoided, leading to a dominating LC-induced repulsion between NPs associated with the replacement of disordered cores by NPs. The templating of NPs by topological defects, beyond the technological inquiries, may enable creation, investigation, and manipulation of unique collective features for a wide range of nanomaterials. PMID:26521895

  3. Tailoring plasmonic properties of gold nanohole arrays for surface-enhanced Raman scattering

    PubMed Central

    Zheng, Peng; Cushing, Scott K.; Suri, Savan; Wu, Nianqiang

    2015-01-01

    The wide plasmonic tuning range of nanotriangle and nanohole array patterns fabricated by nanosphere lithography makes them promising in surface-enhanced Raman scattering (SERS) sensors. Unfortunately, it is challenging to optimize these patterns for SERS sensing because their optical response is a complex mixture of localized and propagating surface plasmons. In this paper, transmission and reflection measurements are combined with finite difference time domain simulations to identify and separate each plasmonic mode, discerning which resonance leads to the electromagnetic field enhancement. The SERS enhancement is found to be dominated by the absorption, which is shifted from the transmission and reflection dips usually used as tuning points, and by the ‘gap’ defects formed within the pattern. These effects have different spectral and geometric dependences, forming two optimization curves which can be used to predict the best performance for a given excitation wavelength. The developed model is verified with experimental SERS measurements for several nanohole sizes and periodicities, and then used to give optimal fabrication parameters for a range of measurement conditions. The results will promote the application of two-dimensional plasmonic nanoarrays in SERS sensors. PMID:25586930

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  5. Large-scale superlattices from colloidal TiO2 nanorods: A facile self-assembly approach

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Liu, Fa-Min

    2016-03-01

    Self-assembly of nanoparticles into superlattices allows a bottom-up approach for fabricating functional materials. For the first time, the colloidal TiO2 nanorods were self-assembled into nine arrays, three of these arrays were highly ordered superlattices over large areas. The relationship between the packing types and the concentration of TiO2 nanorods and oleic acid has been established. The self-assembly process is primarily driven by the density-driven phase evolution and entropic depletion attraction. This facile self-assembly procedure can be used to design and fabricate various materials into superlattices. Furthermore, these superlattices of TiO2 nanorods can be easily tailored for wide ranging devices.

  6. Hierarchical three-dimensional branched hematite nanorod arrays with enhanced mid-visible light absorption for high-efficiency photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Wang, Degao; Chang, Guoliang; Zhang, Yuying; Chao, Jie; Yang, Jianzhong; Su, Shao; Wang, Lihua; Fan, Chunhai; Wang, Lianhui

    2016-06-01

    Herein, we presented hierarchical three-dimensional (3D) branched hematite nanorod arrays (NAs) on transparent fluorine-doped tin oxide (FTO) conductive glass substrates, which exhibited high PEC water splitting performance due to the enhancement of mid-visible light harvesting as well as charge separation and transfer. The introduction of a TiO2 underlayer made the as-prepared 3D branched hematite NAs achieve a photocurrent density of 0.61 mA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE) without high-temperature activation.Herein, we presented hierarchical three-dimensional (3D) branched hematite nanorod arrays (NAs) on transparent fluorine-doped tin oxide (FTO) conductive glass substrates, which exhibited high PEC water splitting performance due to the enhancement of mid-visible light harvesting as well as charge separation and transfer. The introduction of a TiO2 underlayer made the as-prepared 3D branched hematite NAs achieve a photocurrent density of 0.61 mA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE) without high-temperature activation. Electronic supplementary information (ESI) available: Experimental details. See DOI: 10.1039/c6nr03855g

  7. Controlled growth of high-density CdS and CdSe nanorod arrays on selective facets of two-dimensional semiconductor nanoplates.

    PubMed

    Wu, Xue-Jun; Chen, Junze; Tan, Chaoliang; Zhu, Yihan; Han, Yu; Zhang, Hua

    2016-05-01

    The rational synthesis of hierarchical three-dimensional nanostructures with specific compositions, morphologies and functionalities is important for applications in a variety of fields ranging from energy conversion and electronics to biotechnology. Here, we report a seeded growth approach for the controlled epitaxial growth of three types of hierarchical one-dimensional (1D)/two-dimensional (2D) nanostructures, where nanorod arrays of II-VI semiconductor CdS or CdSe are grown on the selective facets of hexagonal-shaped nanoplates, either on the two basal facets of the nanoplate, or on one basal facet, or on the two basal facets and six side facets. The seed engineering of 2D hexagonal-shaped nanoplates is the key factor for growth of the three resulting types of 1D/2D nanostructures. The wurtzite- and zinc-blende-type polymorphs of semiconductors are used to determine the facet-selective epitaxial growth of 1D nanorod arrays, resulting in the formation of different hierarchical three-dimensional (3D) nanostructures. PMID:27102681

  8. Controlled growth of high-density CdS and CdSe nanorod arrays on selective facets of two-dimensional semiconductor nanoplates

    NASA Astrophysics Data System (ADS)

    Wu, Xue-Jun; Chen, Junze; Tan, Chaoliang; Zhu, Yihan; Han, Yu; Zhang, Hua

    2016-05-01

    The rational synthesis of hierarchical three-dimensional nanostructures with specific compositions, morphologies and functionalities is important for applications in a variety of fields ranging from energy conversion and electronics to biotechnology. Here, we report a seeded growth approach for the controlled epitaxial growth of three types of hierarchical one-dimensional (1D)/two-dimensional (2D) nanostructures, where nanorod arrays of II–VI semiconductor CdS or CdSe are grown on the selective facets of hexagonal-shaped nanoplates, either on the two basal facets of the nanoplate, or on one basal facet, or on the two basal facets and six side facets. The seed engineering of 2D hexagonal-shaped nanoplates is the key factor for growth of the three resulting types of 1D/2D nanostructures. The wurtzite- and zinc-blende-type polymorphs of semiconductors are used to determine the facet-selective epitaxial growth of 1D nanorod arrays, resulting in the formation of different hierarchical three-dimensional (3D) nanostructures.

  9. The effect of annealing temperatures to prepare ZnO seeds layer on ZnO nanorods array/TiO2 nanoparticles photoanode

    NASA Astrophysics Data System (ADS)

    Chou, Hsueh-Tao; Hsu, Ho-Chun

    2016-02-01

    In this study, we have fabricated a ZnO nanorods array/TiO2 nanoparticles thin-film as a photoanode, and also investigated the annealing effect at various temperatures (as grown, 250 °C, 350 °C, 450 °C and 550 °C) on ZnO seeds layer. The material properties of ZnO nanorods array were investigated by field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and ultraviolet visible spectroscopy. Besides, the performances of solar cells were evaluated using a source meter (Keithley 2400), which included open-circuit voltage (VOC), short-circuit current density (JSC), fill factor (F.F.) and power conversion efficiency (η%) at one sun (A.M. 1.5G, 100 mW/cm2). The electrochemical properties of the cells were analyzed by electrochemical impedance spectroscopy (EIS). From the EIS results, the cell performances were affected by annealing temperature, especially the fill-factor, at an annealing temperature of 550 °C due to the annealing treatment can enhance the connection between the interfaces of ZnO seeds/TCO, improving the electron lifetime, reducing the electron recombination loss. Finally, the sample annealing at 550 °C has the highest fill-factor of 44, power conversion efficiency of 0.19%, the highest Rct2 of 162.8 Ω and long electron lifetime of 7.25 ms.

  10. Controllable hydrothermal synthesis of rutile TiO2 hollow nanorod arrays on TiCl4 pretreated Ti foil for DSSC application

    NASA Astrophysics Data System (ADS)

    Xi, Min; Zhang, Yulan; Long, Lizhen; Li, Xinjun

    2014-11-01

    Rutile TiO2 nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl4 pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO2 nanorod arrays (H-TNRs). The TiCl4 pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl4 concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ~1.5 μm and diameter of ~200 nm, obtained on 0.15 M TiCl4 pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl4-TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode.

  11. High optical switching speed and flexible electrochromic display based on WO3 nanoparticles with ZnO nanorod arrays' supported electrode

    NASA Astrophysics Data System (ADS)

    Wang, Mingjun; Fang, Guojia; Yuan, Longyan; Huang, Huihui; Sun, Zhenhua; Liu, Nishuang; Xia, Shanhong; Zhao, Xingzhong

    2009-05-01

    The electrochromic (EC) property of WO3 nanoparticles grown on vertically self-aligned ZnO nanorods (ZNRs) is reported. An electrochromic character display based on WO3 nanoparticle-modified ZnO nanorod arrays on a flexible substrate has been fabricated and demonstrated. The ZNRs were first synthesized on ZnO-seed-coated In2O3:Sn (ITO) glass (1 cm2 cell) and polyethylene terephthalate (PET) (4 cm2 cell) substrates by a low temperature hydrothermal method, and then amorphous WO3 nanoparticles were grown directly on the surface of the ZNRs by the pulsed laser deposition (PLD) method. The ZNR-based EC device shows high transparence, good electrochromic stability and fast switching speed (4.2 and 4 s for coloration and bleaching, respectively, for a 1 cm2 cell). The good performance of the ZNR electrode-based EC display can be attributed to the large surface area, high crystallinity and good electron transport properties of the ZNR arrays. Its high contrast, fast switching, good memory and flexible characteristics indicate it is a promising candidate for flexible electrochromic displays or electronic paper.

  12. Effect of growth time on morphology and photoelectrochemical performance of TiO2 nanorod arrays grown on transparent conducting substrates

    NASA Astrophysics Data System (ADS)

    Sui, Mei-rong; Han, Cui-ping; Gu, Xiu-quan; Wang, Yong; Tang, Lu; Tang, Hui

    2015-11-01

    TiO2 nanorod arrays (NRAs) were synthesized directly on the fluorine tin oxide (FTO) coated glass substrates by a facile hydrothermal route. The effects of growth time on the photoelectrochemical (PEC) properties of TiO2 NRAs are investigated. The samples synthesized for 4 h exhibit a photocurrent intensity of 0.37 mA/cm2 at the irradiation of Xe lamp and a bias of 0 V. As the growth time increases, the thickness and order degree of the NRAs are enhanced, but the photocurrent is reduced a lot. It might be associated with the hindering of a high background electron density in NRs due to the long-time hydrothermal reaction in acid environment. Moreover, the decline behavior is observed, which is attributed to the poor charge separation capacity of TiO2 array electrodes and could be suppressed efficiently by applying a suitable positive bias.

  13. Enhanced photoresponse of conformal TiO{sub 2}/Ag nanorod array-based Schottky photodiodes fabricated via successive glancing angle and atomic layer deposition

    SciTech Connect

    Haider, Ali; Biyikli, Necmi; Cansizoglu, Hilal; Cansizoglu, Mehmet Fatih; Karabacak, Tansel; Okyay, Ali Kemal

    2015-01-01

    In this study, the authors demonstrate a proof of concept nanostructured photodiode fabrication method via successive glancing angle deposition (GLAD) and atomic layer deposition (ALD). The fabricated metal-semiconductor nanorod (NR) arrays offer enhanced photoresponse compared to conventional planar thin-film counterparts. Silver (Ag) metallic NR arrays were deposited on Ag-film/Si templates by utilizing GLAD. Subsequently, titanium dioxide (TiO{sub 2}) was deposited conformally on Ag NRs via ALD. Scanning electron microscopy studies confirmed the successful formation of vertically aligned Ag NRs deposited via GLAD and conformal deposition of TiO{sub 2} on Ag NRs via ALD. Following the growth of TiO{sub 2} on Ag NRs, aluminum metallic top contacts were formed to complete the fabrication of NR-based Schottky photodiodes. Nanostructured devices exhibited a photo response enhancement factor of 1.49 × 10{sup 2} under a reverse bias of 3 V.

  14. Zinc oxide nanorods

    NASA Astrophysics Data System (ADS)

    Chik, Hope Wuming

    Non-lithographic, bottom-up techniques have been developed to advance the state of the art and contribute to the development of new material structures, fabrication methods, devices, and applications using the Zinc Oxide material system as a demonstration vehicle. The novel low temperature catalytic vapour-liquid-solid growth process developed is technologically simple, inexpensive, and a robust fabrication technique offering complete control over the physical dimensions of the nanorod such as its diameter and length, and over the positioning of the nanorods for site-selective growth. By controlling the distribution of the Au catalysts with the use of a self-organized anodized aluminum oxide nanopore membrane as a template, we have been able to synthesize highly ordered, hexagonally packed, array of ZnO nanorods spanning a large area. These nanorods are single crystal, hexagonally shaped, indicative of the wurtzite structure, and are vertically aligned to the substrate. By pre-patterning the template, arbitrary nanorod patterns can be formed. We have also demonstrated the assembly of the nanorods into functional devices using controlled methods that are less resource intensive, easily scalable, and adaptable to other material systems, without resorting to the manipulation of each individual nanostructures. Examples of these devices include the random network device that exploits the common attributes of the nanorods, and those formed using an external field to control the nanorod orientation. Two and three terminal device measurements show that the as-grown nanorods are n-type doped, and that by controlling the external optical excitation and its test environment, the photoconductivity can be altered dramatically. Self assemble techniques such as the spontaneous formation of nanodendrites into complex networks of interconnects were studied. Controlled formation of interconnects achieved by controlling the placement of the catalyst is demonstrated by growing the

  15. CdS nanoparticles sensitization of Al-doped ZnO nanorod array thin film with hydrogen treatment as an ITO/FTO-free photoanode for solar water splitting

    PubMed Central

    2012-01-01

    Aluminum-doped zinc oxide (AZO) nanorod array thin film with hydrogen treatment possesses the functions of transparent conducting oxide thin film and 1-D nanostructured semiconductor simultaneously. To enhance the absorption in the visible light region, it is sensitized by cadmium sulfide (CdS) nanoparticles which efficiently increase the absorption around 460 nm. The CdS nanoparticles-sensitized AZO nanorod array thin film with hydrogen treatment exhibits significantly improved photoelectrochemical property. After further heat treatment, a maximum short current density of 5.03 mA cm−2 is obtained under illumination. They not only are much higher than those without CdS nanoparticles sensitization and those without Al-doping and/or hydrogen treatment, but also comparable and even slightly superior to some earlier works for the CdS-sensitized zinc oxide nanorod array thin films with indium tin oxide (ITO) or fluorine-doped tin oxide (FTO) as substrates. This demonstrated successfully that the AZO nanorod array thin film with hydrogen treatment is quite suitable as an ITO/FTO-free photoanode and has great potentials in solar water splitting after sensitization by quantum dots capable of visible light absorption. PMID:23098050

  16. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells.

    PubMed

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-12-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time. PMID:26754938

  17. Synergistic Effect of Surface Plasmonic particles and Surface Passivation layer on ZnO Nanorods Array for Improved Photoelectrochemical Water Splitting.

    PubMed

    Liu, Yichong; Yan, Xiaoqin; Kang, Zhuo; Li, Yong; Shen, Yanwei; Sun, Yihui; Wang, Li; Zhang, Yue

    2016-01-01

    One-dimensional zinc oxide nanorods array exhibit excellent electron mobility and thus hold great potential as photoanode for photoelelctrochemical water splitting. However, the poor absorption of visible light and the prominent surface recombination hider the performance improvement. In this work, Au nanoparticles and aluminium oxide were deposited onto the surface of ZnO nanorods to improve the PEC performance. The localized surface plasmon resonance of Au NPs could expand the absorption spectrum to visible region. Simultaneously, the surface of passivation with Au NPs and Al2O3 largely suppressed the photogenerated electron-hole recombination. As a result, the optimal solar-to-hydrogen efficiency of ZnO/Au/Al2O3 with 5 cycles was 6.7 times that of pristine ZnO, ascribed to the synergistic effect of SPR and surface passivation. This research reveals that the synergistic effect could be used as an important method to design efficient photoanodes for photoelectrochemical devices. PMID:27443692

  18. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-01-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  19. Orientation-Controllable ZnO Nanorod Array Using Imprinting Method for Maximum Light Utilization in Dye-Sensitized Solar Cells.

    PubMed

    Jeong, Huisu; Song, Hui; Lee, Ryeri; Pak, Yusin; Kumaresan, Yogeenth; Lee, Heon; Jung, Gun Young

    2015-12-01

    We present a holey titanium dioxide (TiO2) film combined with a periodically aligned ZnO nanorod layer (ZNL) for maximum light utilization in dye-sensitized solar cells (DSCs). Both the holey TiO2 film and the ZNL were simultaneously fabricated by imprint technique with a mold having vertically aligned ZnO nanorod (NR) array, which was transferred to the TiO2 film after imprinting. The orientation of the transferred ZNL such as laid, tilted, and standing ZnO NRs was dependent on the pitch and height of the ZnO NRs of the mold. The photoanode composed of the holey TiO2 film with the ZNL synergistically utilized the sunlight due to enhanced light scattering and absorption. The best power conversion efficiency of 8.5 % was achieved from the DSC with the standing ZNL, which represented a 33 % improvement compared to the reference cell with a planar TiO2. PMID:26068077

  20. Controllable electrochemical synthesis of ZnO nanorod arrays on flexible ITO/PET substrate and their structural and optical properties

    NASA Astrophysics Data System (ADS)

    Ko, Yeong Hwan; Kim, Myung Sub; Yu, Jae Su

    2012-10-01

    The structural and optical properties of vertically aligned zinc oxide (ZnO) nanorod arrays (NRAs) which were grown on the flexible indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrate (i.e., ITO/PET substrate) with a thin sputtered ZnO seed layer via the electrochemical deposition method were studied. By changing the applied voltage and zinc nitrate concentration, the height/width and density of ZnO NRAs were controlled, with investigation on their crystallinity and optical properties. To understand the effect of ZnO seed layer on the growth property of ZnO nanorods, they were also grown on ITO/PET without any seed layer. Under an applied cathodic voltage of -2 V and zinc nitrate concentration of 10 mM, the ZnO NRAs increased the total transmittance up to 88.7% in the visible wavelength region due to the antireflective property and their X-ray diffraction (0 0 2) peak intensity was largely enhanced. Additionally, the near band edge emission of ZnO was significantly enhanced in photoluminescence spectrum. The light scattering and surface wetting properties were also explored.

  1. Synergistic Effect of Surface Plasmonic particles and Surface Passivation layer on ZnO Nanorods Array for Improved Photoelectrochemical Water Splitting

    PubMed Central

    Liu, Yichong; Yan, Xiaoqin; Kang, Zhuo; Li, Yong; Shen, Yanwei; Sun, Yihui; Wang, Li; Zhang, Yue

    2016-01-01

    One-dimensional zinc oxide nanorods array exhibit excellent electron mobility and thus hold great potential as photoanode for photoelelctrochemical water splitting. However, the poor absorption of visible light and the prominent surface recombination hider the performance improvement. In this work, Au nanoparticles and aluminium oxide were deposited onto the surface of ZnO nanorods to improve the PEC performance. The localized surface plasmon resonance of Au NPs could expand the absorption spectrum to visible region. Simultaneously, the surface of passivation with Au NPs and Al2O3 largely suppressed the photogenerated electron-hole recombination. As a result, the optimal solar-to-hydrogen efficiency of ZnO/Au/Al2O3 with 5 cycles was 6.7 times that of pristine ZnO, ascribed to the synergistic effect of SPR and surface passivation. This research reveals that the synergistic effect could be used as an important method to design efficient photoanodes for photoelectrochemical devices. PMID:27443692

  2. A centimeter-scale sub-10 nm gap plasmonic nanorod array film as a versatile platform for enhancing light-matter interactions

    NASA Astrophysics Data System (ADS)

    Zhou, Zhang-Kai; Xue, Jiancai; Zheng, Zebo; Li, Jiahua; Ke, Yanlin; Yu, Ying; Han, Jun-Bo; Xie, Weiguang; Deng, Shaozhi; Chen, Huanjun; Wang, Xuehua

    2015-09-01

    Strongly coupled plasmonic nanostructures with sub-10 nm gaps can enable intense electric field enhancements which greatly benefit the various light-matter interactions. From the point view of practical applications, such nanostructures should be of low-cost, facile fabrication and processing, large-scale with high-yield of the ultrasmall gaps, and easy for integration with other functional components. However, nowadays techniques for reliable fabrication of these nanostructures usually involve complex, time-consuming, and expensive lithography procedures, which are limited either by their low-throughput or the small areas obtained. On the other hand, so far most of the studies on the sub-10 nm gap nanostructures mainly focused on the surface-enhanced Raman scattering and high-harmonic generations, while leaving other nonlinear optical properties unexplored. In this work, using a scalable process without any lithography procedures, we demonstrated a centimeter-scale ordered plasmonic nanorod array film (PNRAF) with well-defined sub-10 nm interparticle gaps as a versatile platform for strongly enhanced light-matter interactions. Specifically, we showed that due to its plasmon-induced localized electromagnetic field enhancements, the Au PNRAF could exhibit extraordinary intrinsic multi-photon avalanche luminescence (MAPL) and nonlinear saturable absorption (SA). Furthermore, the PNRAF can be easily integrated with semiconductor quantum dots (SQDs) as well as wide bandgap semiconductors to strongly enhance their fluorescence and photocurrent response, respectively. Our method can be easily generalized to nanorod array films consisting of other plasmonic metals and even semiconductor materials, which can have multiple functionalities derived from different materials. Overall, the findings in our study have offered a potential strategy for design and fabrication of nanostructures with ultrasmall gaps for future photonic and optoelectronic applications.Strongly coupled

  3. Preparation of thin hexagonal highly-ordered anodic aluminum oxide (AAO) template onto silicon substrate and growth ZnO nanorod arrays by electrodeposition

    NASA Astrophysics Data System (ADS)

    Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Qaeed, M. A.; Bououdina, M.

    2014-12-01

    In this study, anodic aluminum oxide (AAO) templates of Aluminum thin films onto Ti-coated silicon substrates were prepared for growth of nanostructure materials. Hexagonally highly ordered thin AAO templates were fabricated under controllable conditions by using a two-step anodization. The obtained thin AAO templates were approximately 70 nm in pore diameter and 250 nm in length with 110 nm interpore distances within an area of 3 cm2. The difference between first and second anodization was investigated in details by in situ monitoring of current-time curve. A bottom barrier layer of the AAO templates was removed during dropping the voltage in the last period of the anodization process followed by a wet etching using phosphoric acid (5 wt%) for several minutes at ambient temperature. As an application, Zn nanorod arrays embedded in anodic alumina (AAO) template were fabricated by electrodeposition. Oxygen was used to oxidize the electrodeposited Zn nanorods in the AAO template at 700 °C. The morphology, structure and photoluminescence properties of ZnO/AAO assembly were analyzed using Field-emission scanning electron microscope (FESEM), Energy dispersive X-ray spectroscopy (EDX), Atomic force microscope (AFM), X-ray diffraction (XRD) and photoluminescence (PL).

  4. Pulsed laser deposition of CuInS2 quantum dots on one-dimensional TiO2 nanorod arrays and their photoelectrochemical characteristics

    NASA Astrophysics Data System (ADS)

    Han, Minmin; Chen, Wenyuan; Guo, Hongjian; Yu, Limin; Li, Bo; Jia, Junhong

    2016-06-01

    In the typical solution-based synthesis of colloidal quantum dots (QDs), it always resorts to some surface treatment, ligand exchange processing or post-synthesis processing, which might involve some toxic chemical regents injurious to the performance of QD sensitized solar cells. In this work, the CuInS2 QDs are deposited on the surface of one-dimensional TiO2 nanorod arrays by the pulsed laser deposition (PLD) technique. The CuInS2 QDs are coated on TiO2 nanorods without any ligand engineering, and the performance of the obtained CuInS2 QD sensitized solar cells is optimized by adjusting the laser energy. An energy conversion efficiency of 3.95% is achieved under one sun illumination (AM 1.5, 100 mW cm-2). The improved performance is attributed to enhanced absorption in the longer wavelength region, quick interfacial charge transfer and few chance of carrier recombination with holes for CuInS2 QD-sensitized solar cells. Moreover, the photovoltaic device exhibits high stability in air without any specific encapsulation. Thus, the PLD technique could be further applied for the fabrication of QDs or other absorption materials.

  5. 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.

  6. Low-Temperature Growth of Well-Aligned ZnO Nanorod Arrays by Chemical Bath Deposition for Schottky Diode Application

    NASA Astrophysics Data System (ADS)

    Yuan, Zhaolin

    2015-04-01

    A well-aligned ZnO nanorod array (ZNRA) was successfully grown on an indium tin oxide (ITO) substrate by chemical bath deposition at low temperature. The morphology, crystalline structure, transmittance spectrum and photoluminescence spectrum of as-grown ZNRA were investigated by field emission scanning electron microscopy, x-ray diffraction, ultraviolet-visible spectroscopy and spectrophotometer, respectively. The results of these measurements showed that the ZNRA contained densely packed, aligned nanorods with diameters from 30 nm to 40 nm and a wurtzite structure. The ZNRA exhibited good optical transparency within the visible spectral range, with >80% transmission. Gold (Au) was deposited on top of the ZNRA, and the current-voltage characteristics of the resulting ITO/ZNRA/Au device in the dark were evaluated in detail. The ITO/ZNRA/Au device acted as a Schottky barrier diode with rectifying behaviour, low turn-on voltage (0.6 V), small reverse-bias saturation current (3.73 × 10-6 A), a high ideality factor (3.75), and a reasonable barrier height (0.65 V) between the ZNRA and Au.

  7. Facet control of gold nanorods

    DOE PAGESBeta

    Zhang, Qingfeng; Han, Lili; Jing, Hao; Blom, Douglas A.; Lin, Ye; Xin, Huolin L.; Wang, Hui

    2016-01-21

    While great success has been achieved in fine-tuning the aspect ratios and thereby the plasmon resonances of cylindrical Au nanorods, facet control with atomic level precision on the highly curved nanorod surfaces has long been a significantly more challenging task. The intrinsic structural complexity and lack of precise facet control of the nanorod surfaces remain the major obstacles for the atomic-level elucidation of the structure–property relationships that underpin the intriguing catalytic performance of Au nanorods. Here we demonstrate that the facets of single-crystalline Au nanorods can be precisely tailored using cuprous ions and cetyltrimethylammonium bromide as a unique pair ofmore » surface capping competitors to guide the particle geometry evolution during nanorod overgrowth. By deliberately maneuvering the competition between cuprous ions and cetyltrimethylammonium bromide, we have been able to create, in a highly controllable and selective manner, an entire family of nanorod-derived anisotropic multifaceted geometries whose surfaces are enclosed by specific types of well-defined high-index and low-index facets. This facet-controlled nanorod overgrowth approach also allows us to fine-tune the particle aspect ratios while well-preserving all the characteristic facets and geometric features of the faceted Au nanorods. Furthermore, taking full advantage of the combined structural and plasmonic tunability, we have further studied the facet-dependent heterogeneous catalysis on well-faceted Au nanorods using surface-enhanced Raman spectroscopy as an ultrasensitive spectroscopic tool with unique time-resolving and molecular finger-printing capabilities.« less

  8. Facet Control of Gold Nanorods.

    PubMed

    Zhang, Qingfeng; Han, Lili; Jing, Hao; Blom, Douglas A; Lin, Ye; Xin, Huolin L; Wang, Hui

    2016-02-23

    While great success has been achieved in fine-tuning the aspect ratios and thereby the plasmon resonances of cylindrical Au nanorods, facet control with atomic level precision on the highly curved nanorod surfaces has long been a significantly more challenging task. The intrinsic structural complexity and lack of precise facet control of the nanorod surfaces remain the major obstacles for the atomic-level elucidation of the structure-property relationships that underpin the intriguing catalytic performance of Au nanorods. Here we demonstrate that the facets of single-crystalline Au nanorods can be precisely tailored using cuprous ions and cetyltrimethylammonium bromide as a unique pair of surface capping competitors to guide the particle geometry evolution during nanorod overgrowth. By deliberately maneuvering the competition between cuprous ions and cetyltrimethylammonium bromide, we have been able to create, in a highly controllable and selective manner, an entire family of nanorod-derived anisotropic multifaceted geometries whose surfaces are enclosed by specific types of well-defined high-index and low-index facets. This facet-controlled nanorod overgrowth approach also allows us to fine-tune the particle aspect ratios while well-preserving all the characteristic facets and geometric features of the faceted Au nanorods. Taking full advantage of the combined structural and plasmonic tunability, we have further studied the facet-dependent heterogeneous catalysis on well-faceted Au nanorods using surface-enhanced Raman spectroscopy as an ultrasensitive spectroscopic tool with unique time-resolving and molecular finger-printing capabilities. PMID:26795706

  9. Synthesis and characterization of Cr-doped ZnO nanorod-array photocatalysts with improved activity

    SciTech Connect

    Chang, Chi-Jung Yang, Tsung-Lin; Weng, Yu-Ching

    2014-06-01

    Immobilized photocatalysts with high catalytic activity under UV light were prepared by growing Cr-doped ZnO nanorods on glass substrates by a hydrothermal method. The effects of Cr dopant on the surface texture, crystallinity, surface chemistry, and photoinduced charge separation and their relation with the photocatalytic degradation of Cr-doped ZnO were investigated by scanning electron microscopy, diffuse reflectance spectra, photoelectrochemical scanning electrochemical microscopy, and X-ray photoemission spectroscopy. Adding the appropriate amount of Cr dopant is a powerful way to enhance the separation of charge carriers in ZnO photocatalyst. The photocatalytic activity was improved due to the increase in surface oxygen vacancies, the separation of charge carriers, modification of the band gap, and the large surface area of the doped ZnO nanorod photocatalyst. - Graphical abstract: Photoinduced charge separation and its relation with the photocatalytic degradation activity of Cr-doped ZnO were investigated by photoelectrochemical scanning electrochemical microscopy. - Highlights: • Cr dopant enhances separation of charge carries in ZnO nanorod photocatalyst. • Photoinduced charge carries separation monitored by PEC-SECM. • The higher the photocurrent is, the higher the photocatalytic activity is. • Degradation of DB86 dye solutions under visible light finished within 50 min. • Higher activity due to more oxygen vacancy, tuned band gap and more surface area.

  10. Process of in situ forming well-aligned zinc oxide nanorod arrays on wood substrate using a two-step bottom-up method.

    PubMed

    Liu, Yongzhuang; Fu, Yanchun; Yu, Haipeng; Liu, Yixing

    2013-10-01

    A good nanocrystal covering layer on wood can serve as a protective coating and present some new surface properties. In this study, well-aligned ZnO nanorods (NRs) arrays were successfully grown on wood surface through a two-step bottom-up growth process. The process involved pre-sow seeds and subsequently their growing into NRs under hydrothermal environment. The interface incorporation between wood and ZnO colloid particles in the precursor solution during the seeding process was analyzed and demonstrated through a schematic. The growth process of forming well-aligned ZnO NRs was analyzed by field-emission scanning electron microscopy and X-ray diffraction, which showed that the NRs elongated with increased reaction time. The effects of ZnO crystal form and capping agent on the growth process were studied through different viewpoints. PMID:23880522

  11. Role of Ag2S coupling on enhancing the visible-light-induced catalytic property of TiO2 nanorod arrays

    PubMed Central

    Li, Zhengcao; Xiong, Shan; Wang, Guojing; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    In order to obtain a better photocatalytic performance under visible light, Ag2S-coupled TiO2 nanorod arrays (NRAs) were prepared through the electron beam deposition with glancing angle deposition (GLAD) technique, annealing in air, followed by the successive ionic layer absorption and reaction (SILAR) method. The properties of the photoelectrochemical and photocatalytic degradation of methyl orange (MO) were thus conducted. The presence of Ag2S on TiO2 NRAs was observed to have a significant improvement on the response to visible light. It’s resulted from that Ag2S coupling can improve the short circuit photocurrent density and enhance the photocatalytic activity remarkably. PMID:26790759

  12. Core-Shell Vanadium Modified Titania@β-In2S3 Hybrid Nanorod Arrays for Superior Interface Stability and Photochemical Activity.

    PubMed

    Mumtaz, Asad; Mohamed, Norani Muti; Mazhar, Muhammad; Ehsan, Muhammad Ali; Mohamed Saheed, Mohamed Shuaib

    2016-04-13

    Core-shell rutile TiO2@β-In2S3 and modified V-TiO2@β-In2S3 were synthesized to develop bilayer systems to uphold charge transport via an effective and stable interface. Morphological studies revealed that β-In2S3 was deposited homogeneously on V-TiO2 as compared to unmodified TiO2 nanorod arrays. X-ray photoelectron spectroscopy (XPS) and electron energy loss spectrometry studies verified the presence of various oxidation states of vanadium in rutile TiO2 and the vanadium surface was utilized for broadening the charge collection centers in host substrate layer and hole quencher window. Subsequently, X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectra confirmed the rutile phases of TiO2 and modified V-TiO2 along with the phases of crystalline β-In2S3. XPS valence band study explored the interaction of valence band quazi Fermi levels of β-In2S3 with the conduction band quazi Fermi levels of modified V-TiO2 for enhanced charge collection at the interface. Photoelectrochemical studies show that the photocurrent density of V-TiO2@β-In2S3 is 1.42 mA/cm(2) (1.5AM illumination). Also, the frequency window for TiO2 was broadened by the vanadium modification in rutile TiO2 nanorod arrays, and the lifetime of the charge carrier and stability of the interface in V-TiO2@β-In2S3 were enhanced compared to the unmodified TiO2@β-In2S3. These findings highlight the significance of modifications in host substrates and interfaces, which have profound implications on interphase stability, photocatalysis and solar-fuel-based devices. PMID:26852779

  13. Two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched and P25-coated TiO2 nanotube arrays and their photocurrent performances

    PubMed Central

    2011-01-01

    We report here for the first time the synthesis of two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched TiO2 nanotube arrays (BTs) and P25-coated TiO2 nanotube arrays (PCTs) using two-step method including electrochemical anodization and hydrothermal modification process. Then the photocurrent densities versus applied potentials of BTs, PCTs, and pure TiO2 nanotube arrays (TNTAs) were investigated as well. Interestingly, at -0.11 V and under the same illumination condition, the photocurrent densities of BTs and PCTs show more than 1.5 and 1 times higher than that of pure TNTAs, respectively, which can be mainly attributed to significant improvement of the light-absorbing and charge-harvesting efficiency resulting from both larger and rougher surface areas of BTs and PCTs. Furthermore, these dramatic improvements suggest that BTs and PCTs will achieve better photoelectric conversion efficiency and become the promising candidates for applications in DSSCs, sensors, and photocatalysis. PMID:21711607

  14. Efficient Electron Collection in Hybrid Polymer Solar Cells: In-Situ-Generated ZnO/Poly(3-hexylthiophene) Scaffolded by a TiO2 Nanorod Array.

    PubMed

    Liao, Wen-Pin; Wu, Jih-Jen

    2013-06-01

    A nanoarchitectural hybrid polymer solar cell, integrating the ordered and the bulk heterojunction hybrid polymer solar cells, is fabricated by infiltrating the diethylzinc/poly(3-hexylthiophene) (P3HT) solution into the interstices of the TiO2 nanorod (NR) array. An inorganic network composed of tiny ZnO nanocrystals is constructed in the in-situ-generated hybrid within the interstice of the single-crystalline TiO2 NRs. The TiO2 NR array, which possesses a longer electron lifetime and an appropriate electron-transport rate, serves not only as an electron transporter/collector extended from fluorine-doped tin oxide (FTO) electrode to sustain the efficient electron collection but also as a scaffold to hold the sufficient amount of ZnO/P3HT hybrid. The in-situ-generated ZnO/P3HT hybrid layer with superior charge separation efficiency can therefore be thickened in the presence of a TiO2 NR array for increasing the light-harvesting efficiency. A notable efficiency of 2.46% is therefore attained in the TiO2 NR-ZnO/P3HT hybrid solar cell. PMID:26283138

  15. Arrays of ZnO nanorods decorated with Au nanoparticles as surface-enhanced Raman scattering substrates for rapid detection of trace melamine

    NASA Astrophysics Data System (ADS)

    Yi, Zao; Yi, Yong; Luo, Jiangshan; Li, Xibo; Xu, Xibin; Jiang, Xiaodong; Yi, Yougen; Tang, Yongjian

    2014-10-01

    In this paper, as a new, highly sensitive and uniform hybrid surface-enhanced Raman scattering (SERS) substrate, arrays of ZnO nanorods (ZnO-NRs) decorated with Au nanoparticles (Au-NPs) have been prepared. This hybrid substrate manifests high SERS sensitivity to melamine and a detection limit as low as 1.0×10-10 M (1.26 μg L-1). A maximum enhancement factor of 1.0×109 can be obtained with the ZnO NF-Au (sample 2) film. Au-NPs gaps in the array can create lots of SERS “hot spots” that mainly contribute to the high SERS sensitivity. Moreover, the supporting chemical enhancement effect of ZnO-NRs and the better enrichment effect ascribed to the large surface area of the substrate also help to achieve a lower detection limit. The promising advantages of easy sample pretreatment, short detection time and low cost makes the arrays of ZnO-NRs decorated with Au-NPs substrate a potential detection tool in the field of food safety.

  16. Ag-nanoparticles-decorated NiO-nanoflakes grafted Ni-nanorod arrays stuck out of porous AAO as effective SERS substrates.

    PubMed

    Zhou, Qitao; Meng, Guowen; Huang, Qing; Zhu, Chuhong; Tang, Haibin; Qian, Yiwu; Chen, Bin; Chen, Bensong

    2014-02-28

    NiO-nanoflakes (NiO-NFs) grafted Ni-nanorod (Ni-NR) arrays stuck out of the porous anodic aluminum oxide (AAO) template are achieved by a combinatorial process of AAO-confined electrodeposition of Ni-NRs, selectively etching part of the AAO template to expose the Ni-NRs, wet-etching the exposed Ni-NRs in ammonia to obtain Ni(OH)2-NFs grafted onto the cone-shaped Ni-NRs, and annealing to transform Ni(OH)2-NFs in situ into NiO-NFs. By top-view sputtering, Ag-nanoparticles (Ag-NPs) are decorated on each NiO-NFs grafted Ni-NR (denoted as NiO-NFs@Ni-NR). The resultant Ag-NPs-decorated NiO-NFs@Ni-NR (denoted as Ag-NPs@NiO-NFs@Ni-NR) arrays exhibit not only strong surface-enhanced Raman scattering (SERS) activity but also reproducible SERS-signals over the whole array. It is demonstrated that the strong SERS-activity is mainly ascribed to the high density of sub-10 nm gaps (hot spots) between the neighboring Ag-NPs, the semiconducting NiO-NFs induced chemical enhancement effect, and the lightning rod effect of the cone-shaped Ni-NRs. The three-level hierarchical nanostructure arrays stuck out of the AAO template can be utilized to probe polychlorinated biphenyls (PCBs, a kind of global environmental hazard) with a concentration as low as 5 × 10(-6) M, showing promising potential in SERS-based rapid detection of organic environmental pollutants. PMID:24419246

  17. Enhanced Photoelectrochemical Performance of TiO2 Nanorod Arrays by a 500°C Annealing in Air: Insights into the Mechanism

    NASA Astrophysics Data System (ADS)

    Zhang, Shuang; Gu, Xiuquan; Zhao, Yulong; Qiang, Yinghuai

    2016-01-01

    Oriented, single-crystal TiO2 nanorod arrays (NRAs) were synthesized for photoelectrochemical (PEC) water-splitting by a facile hydrothermal route. It was observed that a 500°C annealing process facilitated enhancing the PEC activity of TiO2 NRAs, in agreement with our previous reports on NRA-related solar cells. Further, electrochemical impedance measurements were employed to investigate the underlying mechanism. Compared with pristine TiO2 NRAs, the 500°C sintered samples showed a positive flat-band shifting of ˜0.12 V as well as a suppression of the donor density. Thus, suggesting that the enhanced PEC performance might be attributed to the widening of depletion layer regions due to the reduction of crystal defects after sintering. The mechanism was also expanded to explain why the dye-sensitized solar cells made with sintered TiO2 NRAs exhibited an 11-times higher power conversion efficiency than those consisting of pristine arrays.

  18. In situ growth of ruthenium oxide-nickel oxide nanorod arrays on nickel foam as a binder-free integrated cathode for hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Xiong, Kun; Chen, Siguo; Li, Li; Deng, Zihua; Wei, Zidong

    2015-01-01

    In this paper we describe a novel catalyst based on RuO2-NiO nanorod arrays constructed in situ on a Ni foam substrate by a hydrothermal process for catalyzing the hydrogen evolution reaction (HER). Field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), linear scanning voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) are used to systematically investigate the microstructure, composition, and electrochemical performance of the catalyst. The prepared electrode exhibits excellent HER performance and long-term stability. This impressive electrochemical performance is largely attributed to the material's unique nanostructure. Noticeable the presence of nickel oxide/hydroxide on the surface of the catalyst promotes the dissociation of water and the formation of hydrogen intermediates that can then adsorb onto the nearby ruthenium species and recombine into molecular hydrogen at a very rapid rate. The hydrothermal method for directly growing electroactive nanostructured arrays on a conductive substrate offers a promising route for developing a new class of Ni-based high performance electrodes for the HER in practical applications.

  19. High Stability Induced by the TiN/Ti Interlayer in Three-Dimensional Si/Ge Nanorod Arrays as Anode in Micro Lithium Ion Battery.

    PubMed

    Yue, Chuang; Yu, Yingjian; Wu, Zhenguo; Sun, Shibo; He, Xu; Li, Juntao; Zhao, Libo; Wu, Suntao; Li, Jing; Kang, Junyong; Lin, Liwei

    2016-03-01

    Three-dimensional (3D) Si/Ge-based micro/nano batteries are promising lab-on-chip power supply sources because of the good process compatibility with integrated circuits and Micro/Nano-Electro-Mechanical System technologies. In this work, the effective interlayer of TiN/Ti thin films were introduced to coat around the 3D Si nanorod (NR) arrays before the amorphous Ge layer deposition as anode in micro/nano lithium ion batteries, thus the superior cycling stability was realized by reason for the restriction of Si activation in this unique 3D matchlike Si/TiN/Ti/Ge NR array electrode. Moreover, the volume expansion properties after the repeated lithium-ion insertion/extraction were experimentally investigated to evidence the superior stability of this unique multilayered Si composite electrode. The demonstration of this wafer-scale, cost-effective, and Si-compatible fabrication for anodes in Li-ion micro/nano batteries provides new routes to configurate more efficient 3D energy storage systems for micro/nano smart semiconductor devices. PMID:26954851

  20. Highly ordered Pb(Zr0.52Ti0.48)O3 piezoelectric nanorod arrays

    NASA Astrophysics Data System (ADS)

    Yang, Su Chul; Sanghadasa, Mohan; Priya, Shashank

    2013-06-01

    One-dimensional (1D) piezoelectric nanostructures have attracted significant attention for a broad range of applications including optoelectronics, thermoelectrics, electrochemical and electromechanical converters. We demonstrate the synthesis of 1D nanostructures based upon Pb(Zr0.52Ti0.48)O3 (PZT) on conductive substrates via sol-gel template synthesis. The vertically aligned PZT nanostructures with heights around one micron were synthesized by vacuum infiltration of sol-gel precursors into highly ordered cylindrical pores of anodized aluminum oxide templates. The 1D nanostructures were developed on large scale platinized silicon wafers and exhibited dense rod-like structure with a uniform diameter of 90 nm and an aspect ratio of 10. Scanning probe microscopy conducted on individual nanorods demonstrated good electromechanical properties with a high piezoelectric magnitude of 41 pm V-1. We believe that this study opens the possibility of developing high performance nanoscale piezoelectric sensors and transducers.

  1. Vertically aligned ZnO@CuS@PEDOT core@shell nanorod arrays decorated with MnO₂ nanoparticles for a high-performance and semi-transparent supercapacitor electrode.

    PubMed

    Rodríguez-Moreno, Jorge; Navarrete-Astorga, Elena; Dalchiele, Enrique A; Schrebler, Ricardo; Ramos-Barrado, José R; Martín, Francisco

    2014-05-30

    Hybrid nano-architectures with high electrochemical performance for supercapacitors have been designed by growing hierarchical ZnO NRs@CuS@PEDOT@MnO2 core@shell heterostructured nanorod arrays on ITO/glass substrates. This hybrid nano-structured electrode exhibits excellent electrochemical performance, with a high specific areal capacitance of 19.85 mF cm(-2), good rate capability, cycling stability and diffused coloured transparency. PMID:24756158

  2. A CdSe thin film: a versatile buffer layer for improving the performance of TiO2 nanorod array:PbS quantum dot solar cells

    NASA Astrophysics Data System (ADS)

    Tan, Furui; Wang, Zhijie; Qu, Shengchun; Cao, Dawei; Liu, Kong; Jiang, Qiwei; Yang, Ying; Pang, Shan; Zhang, Weifeng; Lei, Yong; Wang, Zhanguo

    2016-05-01

    To fully utilize the multiple exciton generation effects in quantum dots and improve the overall efficiency of the corresponding photovoltaic devices, nanostructuralizing the electron conducting layer turns out to be a feasible strategy. Herein, PbS quantum dot solar cells were fabricated on the basis of morphologically optimized TiO2 nanorod arrays. By inserting a thin layer of CdSe quantum dots into the interface of TiO2 and PbS, a dramatic enhancement in the power conversion efficiency from 4.2% to 5.2% was realized and the resulting efficiency is one of the highest values for quantum dot solar cells based on nanostructuralized buffer layers. The constructed double heterojunction with a cascade type-II energy level alignment is beneficial for promoting photogenerated charge separation and reducing charge recombination, thereby responsible for the performance improvement, as revealed by steady-state analyses as well as ultra-fast photoluminescence and photovoltage decays. Thus this paper provides a good buffer layer to the community of quantum dot solar cells.To fully utilize the multiple exciton generation effects in quantum dots and improve the overall efficiency of the corresponding photovoltaic devices, nanostructuralizing the electron conducting layer turns out to be a feasible strategy. Herein, PbS quantum dot solar cells were fabricated on the basis of morphologically optimized TiO2 nanorod arrays. By inserting a thin layer of CdSe quantum dots into the interface of TiO2 and PbS, a dramatic enhancement in the power conversion efficiency from 4.2% to 5.2% was realized and the resulting efficiency is one of the highest values for quantum dot solar cells based on nanostructuralized buffer layers. The constructed double heterojunction with a cascade type-II energy level alignment is beneficial for promoting photogenerated charge separation and reducing charge recombination, thereby responsible for the performance improvement, as revealed by steady

  3. Differentiation and classification of bacteria using vancomycin functionalized silver nanorods array based surface-enhanced Raman spectroscopy and chemometric analysis.

    PubMed

    Wu, Xiaomeng; Huang, Yao-Wen; Park, Bosoon; Tripp, Ralph A; Zhao, Yiping

    2015-07-01

    Twenty seven different bacteria isolates from 12 species were analyzed using intrinsic surface-enhanced Raman scattering (SERS) spectra with recently developed vancomycin coated silver nanorod (VAN AgNR) substrates. The VAN AgNR substrates could generate reproducible SERS spectra of the bacteria with little to no interference from the environment or bacterial by-products as compared to the pristine substrates. By taking advantage of the structural composition of the cellular wall which varies from species to species, the differentiation of bacterial species is demonstrated by using chemometric analyses on those spectra. A second chemometric analysis step within the species cluster is able to differentiate serotypes and strains. The spectral features used for serotype differentiation arises from the surface proteins, while Raman peaks from adenine dominate the differentiation of strains. In addition, due to the intrinsic structural differences in the cell walls, the SERS spectra can distinguish Gram-positive from Gram-negative bacteria with high sensitivity and specificity, as well as 100% accuracy on predicting test samples. Our results provide important insights for using SERS as a bacterial diagnostic tool and further guide the design of a SERS-based detection platform. PMID:25882413

  4. Amorphous TiO2 nanotube-derived synthesis of highly ordered anatase TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Zhao, Cong; Zhu, Dachuan; Cao, Shixiu

    2016-02-01

    A facile method by combining anodic oxidation and hydrothermal method was developed to construct highly ordered anatase TiO2 nanorods (TNRs) and nanotubes (TNTs). In this method, the anodic oxidation was used for preparing highly ordered amorphous TNTs, which subsequently served as highly ordered template for next reaction process. Upon hydrothermal treatment, the as-anodized amorphous template got converted to highly ordered anatase TNTs (blank sample) in without cobalt nitrate solution and TNRs (doped sample) in cobalt nitrate solution, respectively. To our best knowledge, this is first successful attempt to prepare highly ordered anatase TNRs based on the above amorphous template. The scanning electron microscope (SEM) and transmission electron microscope (TEM) observations indicate that the as-prepared anatase TNRs are composed by a large number of anatase TiO2 nanoparticles (TNPs) and the morphology at top of TNRs is different from that of its trunk. Details of the morphology, phase transformation, and growth mechanism of the obtained TNRs are discussed. In addition, the role of Co2+ in the crystallization process had been also discussed.

  5. Plasmon enhanced CdS-quantum dot sensitized solar cell using ZnO nanorods array deposited with Ag nanoparticles as photoanode

    NASA Astrophysics Data System (ADS)

    Eskandari, M.; Ahmadi, V.; Yousefi rad, M.; Kohnehpoushi, S.

    2015-04-01

    CdS-quantum dot sensitized solar cell using ZnO nanorods (ZnO NRs) array deposited with Ag nanoparticles (Ag NPs) as photoanode was fabricated. Light absorption effect of Ag NPs on improvement of the cell performance was investigated. Performance improvement of metal nanoparticles (MNPs) was controlled by the structure design and architecture. Different decorations and densities of Ag NPs were utilized on the photoanode. Results showed that using 5% Ag NPs in the photoanode results in the increased efficiency, fill factor, and circuit current density from 0.28% to 0.60%, 0.22 to 0.29, and 2.18 mA/cm2 to 3.25 mA/cm2, respectively. Also, incident photon-to-current efficiencies (IPCE) results showed that cell performance improvement is related to enhanced absorption in the photoanode, which is because of the surface plasmonic resonance and light scattering of Ag NPs in the photoanode. Measurements of electrochemical impedance spectroscopy revealed that hole transfer kinetics increases with introduction of Ag NPs into photoanode. Also, it is shown that chemical capacitance increases with introduction of Ag NPs. Such increase can be attributed to the surface palsmonic resonance of Ag NPs which leads to absorption of more light in the photoanode and generation of more photoelectron in the photoanode.

  6. Development of Solution-Processed ZnO Nanorod Arrays Based Photodetectors and the Improvement of UV Photoresponse via AZO Seed Layers.

    PubMed

    Zhang, Yuzhu; Xu, Jianping; Shi, Shaobo; Gao, Yanyan; Wang, Chang; Zhang, Xiaosong; Yin, Shougen; Li, Lan

    2016-08-31

    Designing a rational structure and developing an efficient fabrication technique for bottom-up devices offer a promising opportunity for achieving high-performance devices. In this work, we studied how Al-doped ZnO (AZO) seed layer films influence the morphology and optical and electrical properties for ZnO aligned nanorod arrays (NRs) and then the performance of ZnO NRs based ultraviolet photodetectors (UV PDs) with Au/ZnO NRs Schottky junctions and p-CuSCN/n-ZnO NRs heterojunctions. The PD with AZO thin film with 0.5 at. % Al doping (named as AZO (0.5%)) exhibited more excellent photoresponse properties than that with pristine ZnO and AZO (1%) thin films. This phenomenon can be ascribed to the good light transmission of the AZO layer, increased density of the NRs, and improved crystallinity of ZnO NRs. The PDs based on CuSCN/ZnO NRs heterojunctions showed good rectification characteristics in the dark and self-powered UV photoresponse properties with excellent stability and reproducibility under low-intensity illumination conditions. A large responsivity located at 365 nm of 22.5 mA/W was achieved for the PD with AZO (0.5%) thin film without applied bias. The internal electric field originated from p-CuSCN/n-ZnO NRs heterojunctions can separate photogenerated carriers in ZnO NRs and drift toward the corresponding electrode. PMID:27500944

  7. Effect of SiO2 Spacer-Layer Thickness on Localized Surface Plasmon-Enhanced ZnO Nanorod Array LEDs.

    PubMed

    Liu, Weizhen; Xu, Haiyang; Yan, Siyi; Zhang, Cen; Wang, Lingling; Wang, Chunliang; Yang, Liu; Wang, Xinhua; Zhang, Lixia; Wang, Jiannong; Liu, Yichun

    2016-01-27

    Localized surface plasmon (LSP)-enhanced ultraviolet LEDs have been constructed via spin-coating Ag nanoparticles onto ZnO/SiO2 core/shell nanorod array/p-GaN heterostructures. Different from the previous reports where the dielectric spacer-layer thickness was determined only through photoluminescence (PL) characterization, the SiO2 shell thickness in this work is also optimized by actual electroluminescence (EL) measurements to maximize the enhancement. It is interesting to find that the enhancement ratios derived from PL and EL measurements demonstrate different thickness dependences on SiO2 shell: an optimal 3.5-fold PL enhancement was obtained at the SiO2 thickness of 16 nm, while an "abnormal" 7-fold EL enhancement was achieved at the thickness of 12 nm. Time-resolved spectroscopy studies, as well as theoretical estimations and numerical simulations, reveal that the higher-ratio EL enhancement stems from joint contributions, both internal-quantum-efficiency improvement induced by exciton-LSP coupling and light-extraction-efficiency improvement aroused by photon-LSP coupling. PMID:26741886

  8. High performance of Mn-doped CdSe quantum dot sensitized solar cells based on the vertical ZnO nanorod arrays

    NASA Astrophysics Data System (ADS)

    Hou, Juan; Zhao, Haifeng; Huang, Fei; Jing, Qun; Cao, Haibin; Wu, Qiang; Peng, Shanglong; Cao, Guozhong

    2016-09-01

    Doping transition metal ions Mn2+ to semiconductor quantum dots (QDs) are extremely interesting for the development of photovoltaic devices. Quantum dot sensitized solar cells (QDSCs) are able to show promising power conversion efficiencies (PCE) by employing Mn2+ doped QDs. Herein we achieve effective CdS/Mnsbnd CdSe/ZnS QDs co-sensitized vertical ZnO nanorod arrays film that provides an appreciable enhancement in photovoltaic performance. The measured PCE of the solar cells with Mn2+ doped CdSe QDs is 4.14%, which is higher than the efficiency of 2.91% for the solar cells without Mn2+ or a ∼42% increase. The improvement in PCE is ascribed to a higher open-circuit voltage (Voc = 0.74 V) and a superior short-circuit current density (Jsc = 12.6 mA cm-2) with the introduction of Mn2+ into CdSe QDs. The enhancement seen with Mn2+ doped CdSe QDs are investigated and explained by the fact that the enhanced light absorption and reduced charge recombination by the formation of Mnsbnd CdSe passivation layer covering the QDs.

  9. Unique Core-Shell Nanorod Arrays with Polyaniline Deposited into Mesoporous NiCo2O4 Support for High-Performance Supercapacitor Electrodes.

    PubMed

    Jabeen, Nawishta; Xia, Qiuying; Yang, Mei; Xia, Hui

    2016-03-01

    Polyaniline (PANI), one of the most attractive conducting polymers for supercapacitors, demonstrates a great potential as high performance pseudocapacitor materials. However, the poor cycle life owing to structural instability remains as the major hurdle for its practical application; hence, making the structure-to-performance design on the PANI-based supercapacitors is highly desirable. In this work, unique core-shell NiCo2O4@PANI nanorod arrays (NRAs) are rationally designed and employed as the electrode material for supercapacitors. With highly porous NiCo2O4 as the conductive core and strain buffer support and nanoscale PANI layer as the electrochemically active component, such a heterostructure achieves favorably high capacitance while maintaining good cycling stability and rate capability. By adopting the optimally uniform and intimate coating of PANI, the fabricated electrode exhibits a high specific capacitance of 901 F g(-1) at 1 A g(-1) in 1 M H2SO4 electrolyte and outstanding capacitance retention of ∼91% after 3000 cycles at a high current density of 10 A g(-1), which is superior to the electrochemical performance of most reported PANI-based pseudocapacitors in literature. The enhanced electrochemical performance demonstrates the complementary contributions of both componential structures in the hybrid electrode design. Also, this work propels a new direction of utilizing porous matrix as the highly effective support for polymers toward efficient energy storage. PMID:26889785

  10. Coalescence-induced planar defects in GaN layers grown on ordered arrays of nanorods by metal-organic vapour phase epitaxy

    NASA Astrophysics Data System (ADS)

    Huang, Chang-Ning; Shields, Philip A.; Allsopp, Duncan W. E.; Trampert, Achim

    2013-08-01

    The planar defect structure of coalesced GaN layers fabricated on ordered arrays of nanorods and grown by metal-organic vapour phase epitaxy has been studied using conventional and high-resolution transmission electron microscopy. During the process of coalescence, a boundary was created between two pyramids, where I1-type basal plane stacking faults propagating through the overgrown layers are terminated by Frank-Shockley partial dislocations. According to multislice HRTEM simulations of experimental observed images in the [ ? ] zone axis, the step-and hairpin-shaped basal prismatic stacking faults with inclined ? plane are consistent with Drum's structural model, which has a lower formation energy compared with the model proposed by Amelinckx. Based on the observation that there are no stacking faults in the overgrown layers prior to the nanopyramid merging, the mechanism of coalescence induced stacking faults is proposed. This research contributes to the understanding of planar defect formation in III-nitride semiconductor grown by a coalescence process.

  11. Enhanced photoelectrochemical and photocatalytic behaviors of MFe2O4 (M = Ni, Co, Zn and Sr) modified TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Liu, Xiangxuan; Zhu, Zuoming; Wang, Xuanjun; Xie, Zheng

    2016-07-01

    Modified TiO2 nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe2O4, M = Ni, Co, Zn, and Sr), are utilized to modify the well aligned TiO2 nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe2O4/TiO2 NRAs show obvious red shift into the visible light region compared with the TiO2 NRAs. In particular, NiFe2O4 modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO2 NRAs. Furthermore, the separation and transfer of charge carriers after MFe2O4 modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe2O4/TiO2 NRAs is proposed. Through comparison among different transition metals modified TiO2 with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO2 nanomaterials as visible light active photocatalysts.

  12. Enhanced photoelectrochemical and photocatalytic behaviors of MFe2O4 (M = Ni, Co, Zn and Sr) modified TiO2 nanorod arrays.

    PubMed

    Gao, Xin; Liu, Xiangxuan; Zhu, Zuoming; Wang, Xuanjun; Xie, Zheng

    2016-01-01

    Modified TiO2 nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe2O4, M = Ni, Co, Zn, and Sr), are utilized to modify the well aligned TiO2 nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe2O4/TiO2 NRAs show obvious red shift into the visible light region compared with the TiO2 NRAs. In particular, NiFe2O4 modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO2 NRAs. Furthermore, the separation and transfer of charge carriers after MFe2O4 modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe2O4/TiO2 NRAs is proposed. Through comparison among different transition metals modified TiO2 with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO2 nanomaterials as visible light active photocatalysts. PMID:27464888

  13. Controllable in situ photo-assisted chemical deposition of CdSe quantum dots on ZnO/CdS nanorod arrays and its photovoltaic application.

    PubMed

    Wang, Xinwei; Liu, Hong; Shen, Wenzhong

    2016-02-26

    Compound semiconductors have been widely applied in the energy field as light-harvesting materials, conducting substrates and other functional parts. Nevertheless, to effectively grow them in various forms toward objective applications, limitations have often been met to achieving high growth rate, simplicity of method and controllability of growing processes simultaneously. In this work, we have grown a uniform CdSe layer on ZnO/CdS nanorod arrays by a novel in situ photo-assisted chemical deposition method. The morphology and quality of the as-formed material could be significantly influenced by tuning the optical parameters of the injected light. Due to the effect of injected light on the key reactions during the growth, a modified natural light with removal of the UV and IR components seems to be more suitable than monochromic light. An efficiency of 3.59% was achieved without any additional treatment, significantly higher than the efficiency of 2.88% of the sample by conventional CBD method under similar conditions with growth rate one order of magnitude higher. In general, the result has suggested its potential importance for other compound materials and opto-electronic devices. PMID:26821250

  14. Controllable in situ photo-assisted chemical deposition of CdSe quantum dots on ZnO/CdS nanorod arrays and its photovoltaic application

    NASA Astrophysics Data System (ADS)

    Wang, Xinwei; Liu, Hong; Shen, Wenzhong

    2016-02-01

    Compound semiconductors have been widely applied in the energy field as light-harvesting materials, conducting substrates and other functional parts. Nevertheless, to effectively grow them in various forms toward objective applications, limitations have often been met to achieving high growth rate, simplicity of method and controllability of growing processes simultaneously. In this work, we have grown a uniform CdSe layer on ZnO/CdS nanorod arrays by a novel in situ photo-assisted chemical deposition method. The morphology and quality of the as-formed material could be significantly influenced by tuning the optical parameters of the injected light. Due to the effect of injected light on the key reactions during the growth, a modified natural light with removal of the UV and IR components seems to be more suitable than monochromic light. An efficiency of 3.59% was achieved without any additional treatment, significantly higher than the efficiency of 2.88% of the sample by conventional CBD method under similar conditions with growth rate one order of magnitude higher. In general, the result has suggested its potential importance for other compound materials and opto-electronic devices.

  15. Dependencies of the emission behavior and quantum well structure of a regularly-patterned, InGaN/GaN quantum-well nanorod array on growth condition.

    PubMed

    Liao, Che-Hao; Tu, Charng-Gan; Chang, Wen-Ming; Su, Chia-Ying; Shih, Pei-Ying; Chen, Hao-Tsung; Yao, Yu-Feng; Hsieh, Chieh; Chen, Horng-Shyang; Lin, Chun-Han; Yu, Chih-Kang; Kiang, Yean-Woei; Yang, C C

    2014-07-14

    To achieve green emission from the sidewall non-polar quantum wells (QWs) of a GaN nanorod (NR) light-emitting diode, regularly patterned InGaN/GaN QW NR arrays are grown under various growth conditions of indium supply rate, QW growth temperature, and QW growth time for comparing their emission wavelength variations of the top-face c-plane and sidewall m-plane QWs based on photoluminescence and cathodoluminescence (CL) measurements. Although the variation trends of QW emission wavelength by changing those growth conditions in the NR structure are similar to those in the planar structure, the emission wavelength range of the QWs on an NR is significantly shorter than that in a planar structure under the same growth conditions. Under the growth conditions for a longer NR QW emission wavelength, the difference of emission wavelength between the top-face and sidewall QWs is smaller. Also, the variation range of the emission wavelength from the sidewall QWs over different heights on the sidewall becomes larger. On the other hand, strain state analysis based on transmission electron microscopy is undertaken to calibrate the average QW widths and average indium contents in the two groups of QW of an NR. The variation trends of the calibrated QW widths and indium contents are consistent with those of the CL emission wavelengths from various portions of NR QWs. PMID:25090544

  16. A CdSe thin film: a versatile buffer layer for improving the performance of TiO2 nanorod array:PbS quantum dot solar cells.

    PubMed

    Tan, Furui; Wang, Zhijie; Qu, Shengchun; Cao, Dawei; Liu, Kong; Jiang, Qiwei; Yang, Ying; Pang, Shan; Zhang, Weifeng; Lei, Yong; Wang, Zhanguo

    2016-05-21

    To fully utilize the multiple exciton generation effects in quantum dots and improve the overall efficiency of the corresponding photovoltaic devices, nanostructuralizing the electron conducting layer turns out to be a feasible strategy. Herein, PbS quantum dot solar cells were fabricated on the basis of morphologically optimized TiO2 nanorod arrays. By inserting a thin layer of CdSe quantum dots into the interface of TiO2 and PbS, a dramatic enhancement in the power conversion efficiency from 4.2% to 5.2% was realized and the resulting efficiency is one of the highest values for quantum dot solar cells based on nanostructuralized buffer layers. The constructed double heterojunction with a cascade type-II energy level alignment is beneficial for promoting photogenerated charge separation and reducing charge recombination, thereby responsible for the performance improvement, as revealed by steady-state analyses as well as ultra-fast photoluminescence and photovoltage decays. Thus this paper provides a good buffer layer to the community of quantum dot solar cells. PMID:27124650

  17. Improved photoelectrochemical water oxidation kinetics using a TiO2 nanorod array photoanode decorated with graphene oxide in a neutral pH solution.

    PubMed

    Chae, Sang Youn; Sudhagar, Pitchaimuthu; Fujishima, Akira; Hwang, Yun Jeong; Joo, Oh-Shim

    2015-03-28

    We prepared TiO2 nanorod (NR) arrays on a fluorine-doped tin oxide substrate and decorated with graphene oxide (GO) to study their photoelectrochemical (PEC) water oxidation activities in two different electrolytes. The PEC performances of GO-decorated TiO2 NR photoanodes were characterized by optical and electrochemical impedance spectroscopy measurements. In 1 M KOH, the photocurrent density of the TiO2 NR film decreased after deposition of GO, while in the neutral pH electrolyte (phosphate buffered 0.5 M Na2SO4), the TiO2 NR photoanode showed enhanced performance after deposition with the 2 wt% GO solution. This was a consequence of the decrease in charge transfer resistance between the electrode surface and the electrolyte. The improvement of photocurrents by GO decoration was obvious near the onset potential of the photocurrents in the neutral pH electrolyte. These opposite contributions of GO on the TiO2 NR photoanodes suggest that GO can promote water oxidation effectively in a neutral electrolyte because depending on the pH of the electrolyte, different chemical species interact with the surface of the photoanode in the water oxidation reaction. PMID:25711207

  18. Enhanced photoelectrochemical and photocatalytic behaviors of MFe2O4 (M = Ni, Co, Zn and Sr) modified TiO2 nanorod arrays

    PubMed Central

    Gao, Xin; Liu, Xiangxuan; Zhu, Zuoming; Wang, Xuanjun; Xie, Zheng

    2016-01-01

    Modified TiO2 nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe2O4, M = Ni, Co, Zn, and Sr), are utilized to modify the well aligned TiO2 nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe2O4/TiO2 NRAs show obvious red shift into the visible light region compared with the TiO2 NRAs. In particular, NiFe2O4 modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO2 NRAs. Furthermore, the separation and transfer of charge carriers after MFe2O4 modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe2O4/TiO2 NRAs is proposed. Through comparison among different transition metals modified TiO2 with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO2 nanomaterials as visible light active photocatalysts. PMID:27464888

  19. Solar hydrogen generation by a CdS-Au-TiO2 sandwich nanorod array enhanced with Au nanoparticle as electron relay and plasmonic photosensitizer.

    PubMed

    Li, Jiangtian; Cushing, Scott K; Zheng, Peng; Senty, Tess; Meng, Fanke; Bristow, Alan D; Manivannan, Ayyakkannu; Wu, Nianqiang

    2014-06-11

    This paper presents a sandwich-structured CdS-Au-TiO2 nanorod array as the photoanode in a photoelectrochemical cell (PEC) for hydrogen generation via splitting water. The gold nanoparticles sandwiched between the TiO2 nanorod and the CdS quantum dot (QD) layer play a dual role in enhancing the solar-to-chemical energy conversion efficiency. First, the Au nanoparticles serve as an electron relay, which facilitates the charge transfer between CdS and TiO2 when the CdS QDs are photoexcited by wavelengths shorter than 525 nm. Second, the Au nanoparticles act as a plasmonic photosensitizer, which enables the solar-to-hydrogen conversion at wavelengths longer than the band edge of CdS, extending the photoconversion wavelength from 525 to 725 nm. The dual role of Au leads to a photocurrent of 4.07 mA/cm(2) at 0 V (vs Ag|AgCl) under full solar spectrum irradiation and a maximum solar-to-chemical energy conversion efficiency of 2.8%. An inversion analysis is applied to the transient absorption spectroscopy data, tracking the transfer of electrons and holes in the heterostructure, relating the relaxation dynamics to the underlying coupled rate equation and revealing that trap-state Auger recombination is a dominant factor in interfacial charge transfer. It is found that addition of Au nanoparticles increases the charge-transfer lifetime, reduces the trap-state Auger rate, suppresses the long-time scale back transfer, and partially compensates the negative effects of the surface trap states. Finally, the plasmonic energy-transfer mechanism is identified as direct transfer of the plasmonic hot carriers, and the interfacial Schottky barrier height is shown to modulate the plasmonic hot electron transfer and back transfer. Transient absorption characterization of the charge transfer shows defect states cannot be ignored when designing QD-sensitized solar cells. This facile sandwich structure combines both the electrical and the optical functions of Au nanoparticles into a

  20. Towards high efficiency air-processed near-infrared responsive photovoltaics: bulk heterojunction solar cells based on PbS/CdS core-shell quantum dots and TiO2 nanorod arrays.

    PubMed

    Gonfa, Belete Atomsa; Kim, Mee Rahn; Delegan, Nazar; Tavares, Ana C; Izquierdo, Ricardo; Wu, Nianqiang; El Khakani, My Ali; Ma, Dongling

    2015-06-14

    Near infrared (NIR) PbS quantum dots (QDs) have attracted significant research interest in solar cell applications as they offer several advantages, such as tunable band gaps, capability of absorbing NIR photons, low cost solution processability and high potential for multiple exciton generation. Nonetheless, reports on solar cells based on NIR PbS/CdS core-shell QDs, which are in general more stable and better passivated than PbS QDs and thus more promising for solar cell applications, remain very rare. Herein we report high efficiency bulk heterojunction QD solar cells involving hydrothermally grown TiO2 nanorod arrays and PbS/CdS core-shell QDs processed in air (except for a device thermal annealing step) with a photoresponse extended to wavelengths >1200 nm and with a power conversion efficiency (PCE) as high as 4.43%. This efficiency was achieved by introducing a thin, sputter-deposited, uniform TiO2 seed layer to improve the interface between the TiO2 nanorod arrays and the front electrode, by optimizing TiO2 nanorod length and by conducting QD annealing treatment to enhance charge carrier transport. It was found that the effect of the seed layer became more obvious when the TiO2 nanorods were longer. Although photocurrent did not change much, both open circuit voltage and fill factor clearly changed with TiO2 nanorod length. This was mainly attributed to the variation of charge transport and recombination processes, as evidenced by series and shunt resistance studies. The optimal PCE was obtained at the nanorod length of ∼450 nm. Annealing is shown to further increase the PCE by ∼18%, because of the improvement of charge carrier transport in the devices as evidenced by considerably increased photocurrent. Our results clearly demonstrate the potential of the PbS/CdS core-shell QDs for the achievement of high PCE, solution processable and NIR responsive QD solar cells. PMID:25975363

  1. Tailoring the sensing capabilities of nanohole arrays in gold films with Wood's anomaly-surface plasmon polaritons

    SciTech Connect

    McMahon, J. M; Henzie, J.; Odom, T. W.; Schatz, G. C.; Gray, S. K.; Northwestern Univ.

    2009-01-01

    Surface plasmon polaritons (SPPs) and diffraction effects such as Rayleigh anomalies (RAs) play key roles in the transmission of light through periodic subwavelength hole arrays in metal films. Using a combination of theory and experiment we show how refractive index (RI) sensitive transmission features arise from hole arrays in thin gold films. We show that large transmission amplitude changes occur over a narrow range of RI values due to coupling between RAs and SPPs on opposite sides of the metal film. Furthermore, we show how to predict, on the basis of a relatively simple analysis, the periodicity and other system parameters that should be used to achieve this 'RA-SPP' effect for any desired RI range.

  2. The multivariate detection limit for Mycoplasma pneumoniae as determined by Nanorod Array-Surface Enhanced Raman Spectroscopy and comparison with limit of detection by qPCR

    PubMed Central

    Henderson, Kelley C.; Sheppard, Edward S.; Rivera-Betancourt, Omar E.; Choi, Joo-Young; Dluhy, Richard A.; Thurman, Kathleen A.; Winchell, Jonas M.; Krause, Duncan C.

    2015-01-01

    Mycoplasma pneumoniae is a cell wall-less bacterial pathogen of the human respiratory tract that accounts for up to 20% of community-acquired pneumonia. At present, the standard for detection and genotyping is quantitative polymerase chain reaction (qPCR), which can exhibit excellent sensitivity but lacks standardization and has limited practicality for widespread, point-of-care use. We previously described a Ag nanorod array-surface enhanced Raman spectroscopy (NA-SERS) biosensing platform capable of detecting M. pneumoniae in simulated and true clinical throat swab samples with statistically significant specificity and sensitivity. We report here that differences in sample preparation influence the integrity of mycoplasma cells for NA-SERS analysis, which in turn impacts the resulting spectra. We have established a multivariate detection limit (MDL) using NA-SERS for M. pneumoniae intact-cell sample preparations. Using an adaptation of International Union of Pure and Applied Chemistry (IUPAC)-recommended methods for analyzing multivariate data sets, we found that qPCR had roughly 10× better detection limits than NA-SERS when expressed in CFU/ml and DNA concentration (fg). However, the NA-SERS MDL for intact M. pneumoniae was 5.3 ± 1.0 genome equivalents (cells/μl). By comparison, qPCR of a parallel set of samples yielded a limit of detection of 2.5 ± 0.25 cells/μl. Therefore, for certain standard metrics NA-SERS provides a multivariate detection limit for M. pneumoniae that is essentially identical to that determined via qPCR. PMID:25335653

  3. Using carbon nanotubes-gold nanocomposites to quench energy from pinnate titanium dioxide nanorods array for signal-on photoelectrochemical aptasensing.

    PubMed

    Deng, Wenping; Shen, Lei; Wang, Xiu; Yang, Chunlei; Yu, Jinghua; Yan, Mei; Song, Xianrang

    2016-08-15

    On the basis of the absorption and emission spectra overlap, an enhanced resonance energy transfer caused by excition-plasmon resonance between carbon nanotubes-gold nanoparticles (CNTs-Au) and pinnate titanium dioxide nanorods array (P-TiO2 NA) was obtained. Three-dimensional single crystalline P-TiO2 were prepared successfully on fluorine-doped tin oxide conducting glass (FTO glass), and its optical absorption properties and photoelectrochemical (PEC) properties were investigated. With the synergy of CNTs-Au as energy acceptor, it resulted in the enhancement of energy transfer between excited P-TiO2 NA and CNTs-Au. Upon the novel sandwichlike structure formed via DNA hybridization, the exciton produced in P-TiO2 NA was annihilated and a damped photocurrent was obtained. 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 the optimal conditions, the PEC aptasensor for CEA determination exhibited a linear range from 0.001 to 2.5ngmL(-1) with a detection limit of 0.39pgmL(-1) and was satisfactory for clinical sample detection. Furthermore, the proposed aptasensor shows satisfying performance, such as easy preparation, rapid detection and so on. Moreover, since different aptamer can specifically bind to different target molecules, the designed strategy has an expansive application for the construction of versatile PEC platforms. PMID:27088368

  4. The multivariate detection limit for Mycoplasma pneumoniae as determined by nanorod array-surface enhanced Raman spectroscopy and comparison with limit of detection by qPCR.

    PubMed

    Henderson, Kelley C; Sheppard, Edward S; Rivera-Betancourt, Omar E; Choi, Joo-Young; Dluhy, Richard A; Thurman, Kathleen A; Winchell, Jonas M; Krause, Duncan C

    2014-12-21

    Mycoplasma pneumoniae is a cell wall-less bacterial pathogen of the human respiratory tract that accounts for up to 20% of community-acquired pneumonia. At present, the standard for detection and genotyping is quantitative polymerase chain reaction (qPCR), which can exhibit excellent sensitivity but lacks standardization and has limited practicality for widespread, point-of-care use. We previously described a Ag nanorod array-surface enhanced Raman spectroscopy (NA-SERS) biosensing platform capable of detecting M. pneumoniae in simulated and true clinical throat swab samples with statistically significant specificity and sensitivity. We report here that differences in sample preparation influence the integrity of mycoplasma cells for NA-SERS analysis, which in turn impacts the resulting spectra. We have established a multivariate detection limit (MDL) using NA-SERS for M. pneumoniae intact-cell sample preparations. Using an adaptation of International Union of Pure and Applied Chemistry (IUPAC)-recommended methods for analyzing multivariate data sets, we found that qPCR had roughly 10× better detection limits than NA-SERS when expressed in CFU ml(-1) and DNA concentration (fg). However, the NA-SERS MDL for intact M. pneumoniae was 5.3 ± 1.0 genome equivalents (cells per μl). By comparison, qPCR of a parallel set of samples yielded a limit of detection of 2.5 ± 0.25 cells per μl. Therefore, for certain standard metrics NA-SERS provides a multivariate detection limit for M. pneumoniae that is essentially identical to that determined via qPCR. PMID:25335653

  5. Double Fano resonances in plasmon coupling nanorods

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Jin, Jie

    2015-05-01

    Fano resonances are investigated in nanorods with symmetric lengths and side-by-side assembly. Single Fano resonance can be obtained by a nanorod dimer, and double Fano resonances are shown in nanorod trimers with side-by-side assembly. With transverse plasmon excitation, Fano resonances are caused by the destructive interference between a bright superradiant mode and dark subradiant modes. The bright mode originates from the electric plasmon resonance, and the dark modes originate from the magnetic resonances induced by near-field inter-rod coupling. Double Fano resonances result from double dark modes at different wavelengths, which are induced and tuned by the asymmetric gaps between the adjacent nanorods. Fano resonances show a high figure of merit and large light extinction in the periodic array of assembled nanorods, which can potentially be used in multiwavelength sensing in the visible and near-infrared regions.

  6. Tailoring the High-Q LC Filter Arrays for Readout of Kilo-Pixel TES Arrays in the SPICA-SAFARI Instrument

    NASA Astrophysics Data System (ADS)

    Bruijn, M. P.; Gottardi, L.; den Hartog, R. H.; van der Kuur, J.; van der Linden, A. J.; Jackson, B. D.

    2014-08-01

    Following earlier presentations of arrays of high quality factor (Q 10.000) superconducting resonators in the MHz regime, we report on improvement of the packing density of resonance frequencies to 160 in the 1-3 MHz band. Spread in the spacing of resonances is found to be limited to 1 kHz (1 with the present fabrication procedure. The present packing density of frequencies and chip area approaches the requirements for the SAFARI instrument on the SPICA mission (in preparation). The a-Si:H dielectric layer in the planar S-I-S capacitors shows a presently unexplained apparent negative effective series resistance, depending on operating temperature and applied testing voltage.

  7. Interaction of phospholipid with silver nanorods

    NASA Astrophysics Data System (ADS)

    Anju, K. N.; Mahesh, S.; Kalarikkal, Nandakumar

    2014-01-01

    Development of a simple method for incorporating phospholipids onto the surfaces of anisotropic silver nanorods as a stepping-stone for creating responsive and multifunctional nanocomposites. 1, 2-distearoyl-sn-glycero-3-phosphatidylcholine (DSPC)-silver nanorod composites were prepared by immobilizing liposomes onto the surface of cetyltrimethylammonium bromide (CTAB) capped silver nanorods. Here we report the role of phospholipids to control the self assembly of silver nanorods into agglomerate architectures ranging from open "end-to-end" networks to densely packed "side-to-side" arrays. The tuning of electrostatic interactions within the phospholipid layers is governed to lipid silver nanorod assembly and also about the organization of phospholipid layers themselves around nanorod surfaces. The initial studies on passive lipid functionalized nanorods could serve as the groundwork for introducing active components into these systems to make more switchable or reconfigurable nanocomposite material. Changing the surface species on silver nanorods from CTAB to DSPC is reflected in ξ- potential measurements. The surface morphology is studied using SEM and TEM. The optical studies are carried out using UV-Vis spectroscopy.

  8. Electronic Structure Engineering of Cu2O Film/ZnO Nanorods Array All-Oxide p-n Heterostructure for Enhanced Photoelectrochemical Property and Self-powered Biosensing Application

    NASA Astrophysics Data System (ADS)

    Kang, Zhuo; Yan, Xiaoqin; Wang, Yunfei; Bai, Zhiming; Liu, Yichong; Zhang, Zheng; Lin, Pei; Zhang, Xiaohui; Yuan, Haoge; Zhang, Xueji; Zhang, Yue

    2015-01-01

    We have engineered the electronic structure at the interface between Cu2O and ZnO nanorods (NRs) array, through adjusting the carrier concentration of Cu2O. The electrodeposition of Cu2O at pH 11 acquired the highest carrier concentration, resulting in the largest interfacial electric field between Cu2O and ZnO, which finally led to the highest separation efficiency of photogenerated charge carriers. 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 glutathione (GSH) in PBS buffer even at applied bias of 0 V which made the device self-powered. Besides, the favorable selectivity, high reproducibility and extremely wide detection range, make such heterostructure a promising candidate for PEC biosensing applications, probably for the extended field of PEC water splitting or other solar photovoltaic beacons.

  9. Faceted Gold Nanorods: Nanocuboids, Convex Nanocuboids, and Concave Nanocuboids.

    PubMed

    Zhang, Qingfeng; Zhou, Yadong; Villarreal, Esteban; Lin, Ye; Zou, Shengli; Wang, Hui

    2015-06-10

    Au nanorods are optically tunable anisotropic nanoparticles with built-in catalytic activities. The state-of-the-art seed-mediated nanorod synthesis offers excellent control over the aspect ratios of cylindrical Au nanorods, which enables fine-tuning of plasmon resonances over a broad spectral range. However, facet control of Au nanorods with atomic-level precision remains significantly more challenging. The coexistence of various types of low-index and high-index facets on the highly curved nanorod surfaces makes it extremely challenging to quantitatively elucidate the atomic-level structure-property relationships that underpin the catalytic competence of Au nanorods. Here we demonstrate that cylindrical Au nanorods undergo controlled facet evolution during their overgrowth in the presence of Cu(2+) and cationic surfactants, resulting in the formation of anisotropic nanostructures enclosed by well-defined facets, such as low-index faceting nanocuboids and high-index faceting convex nanocuboids and concave nanocuboids. These faceted Au nanorods exhibit enriched optical extinction spectral features, broader plasmonic tuning range, and enhanced catalytic tunability in comparison to the conventional cylindrical Au nanorods. The capabilities to both fine-tailor the facets and fine-tune the plasmon resonances of anisotropic Au nanoparticles open up unique opportunities for us to study, in great detail, the facet-dependent interfacial molecular transformations on Au nanocatalysts using surface-enhanced Raman scattering as a time-resolved spectroscopic tool. PMID:25927399

  10. Effects of calcination treatment on the morphology, crystallinity, and photoelectric properties of all-solid-state dye-sensitized solar cells assembled by TiO2 nanorod arrays.

    PubMed

    Sun, Xianmiao; Sun, Qiong; Li, Yang; Sui, Lina; Dong, Lifeng

    2013-11-14

    TiO2 has been extensively investigated due to its unique photoelectric properties. In this study, oriented single-crystal rutile TiO2 nanorod arrays were synthesized and then calcined at different temperatures in the atmosphere. The morphology and crystalline characterization indicated that the length of TiO2 nanorods increased rapidly and the nanorods became aggregated and fragile after calcination, yet the sintering treatment seemed to have almost no effect on the crystallinity. To obtain the all-solid-state, dye-sensitized solar cells (DSSCs), a newly reported solid inorganic semiconductor, CsSnI2.95F0.05, was employed as the electrolyte, and the Pt deposited on the conductive side of the fluorine-doped tin oxide (FTO) glass substrate was used as the counter-electrode. The effects of the calcination treatment on the photoelectric properties of the solar cells, including external quantum efficiency (EQE), open circuit voltage (V(OC)), short-circuit current (J(SC)), and photoelectric conversion efficiency (η), were investigated under the illumination of a solar simulator. As a result, all of the EQE, V(OC), J(SC), and η values of the cells first increased and then declined with the increase of calcination temperatures, and the highest η of 2.81% was obtained by the cell assembled with its TiO2 electrode sintered at 450 °C for 3 h, a value almost 2.5 times that of the non-sintered sample (1.1%). PMID:24071636

  11. Highly Sensitive and Selective Surface-Enhanced Raman Spectroscopy Label-free Detection of 3,3',4,4'-Tetrachlorobiphenyl Using DNA Aptamer-Modified Ag-Nanorod Arrays.

    PubMed

    Sun, Kexi; Huang, Qing; Meng, Guowen; Lu, Yilin

    2016-03-01

    An improved label-free approach for highly sensitive and selective detection of 3,3',4,4'-tetrachlorobiphenyl (PCB-77), a type of polychlorinated biphenyl, via surface-enhanced Raman spectroscopy (SERS) using DNA aptamer-modified Ag-nanorod arrays as the effective substrate is reported. The devised system consists of Ag-nanorod (Ag-NR) arrays with the PCB-77 binding aptamers anchored covalently to the Ag surfaces through a thiol linker. The aptamers are made of single-stranded DNA (ssDNA) oligomers, with one end standing on the Ag surface, and upon conjugation with PCB-77, the ssDNA molecules can change their conformation to hairpin loops, so that the Raman intensity of guanines at the other end of the DNA strand increases accordingly. As such, the intensity ratio I(656 cm(-1))/I(733 cm(-1)) increases concomitantly with the increase of the concentration of PCB-77, making the quantitative evaluation of trace amounts of PCB-77 attainable. Moreover, it is found that the DNA aptamer-based Ag-NR arrays can be more responsive with a lower and optimal density of the DNA molecules modified on the substrate surface, and the best sensitivity for detection of PCB-77 can be achieved with the lower detection limit approaching 3.3 × 10(-8) M. This work therefore demonstrates that the design of aptamer-modified Ag-NRs can be used as a practically promising SERS substrate for label-free trace detection of persistent organic pollutants (POPs) in the environment. PMID:26849392

  12. Functionalized ZnO@TiO2 nanorod array film loaded with ZnIn(0.25)Cu(0.02)S(1.395) solid-solution: synthesis, characterization and enhanced visible light driven water splitting.

    PubMed

    Wang, Ruosong; Xu, Xiaoxue; Zhang, Yi; Chang, Zhimin; Sun, Zaicheng; Dong, Wen-Fei

    2015-07-01

    We have designed a novel semiconductor core/layer nanostructure of a uniform ZnO@TiO2 nanorod array modified with a ZnIn0.25Cu0.02S1.395 solid-solution on the surface via a facile hydrothermal synthesis. This novel nanostructure combines the merits of all components and meets the requirements of photovoltaic system application. An intimate PN heterojunction is formed from the ZnO@TiO2 nanorod and polymetallic sulphide solid-solution, which is remarkably beneficial for the effective visible light absorption and rapid charge carrier separation. The nanostructures exhibit higher photocurrent and incident photon to electron conversion efficiency (IPCE) under no bias potential versus the Ag/AgCl electrode. We also analyzed the interface and photoelectrochemical characteristics of the nanostructure and revealed the kinetic process of the electron and hole transmission. In addition, the photoanode test shows the hydrogen production capability of the nanostructures from solar water splitting. These results verified that the ZnO and TiO2 can be sensitized by the polymetallic sulfide for UV-Vis light driven energy conversion. Importantly, the approach we used to design the photoanode enables the development of micro-nano electronic devices with enhanced performance. PMID:26055666

  13. Core-Shell Sn-Ni-Cu-Alloy@Carbon Nanorods to Array as Three-Dimensional Anode by Nanoelectrodeposition for High-Performance Lithium Ion Batteries.

    PubMed

    Peng, Hao; Li, Rui; Hu, Jiangtao; Deng, Wenjun; Pan, Feng

    2016-05-18

    We report the synthesis of a novel three-dimensional anode based on the core-shell Sn-Ni-Cu-alloy@carbon nanorods which was fabricated by pulse nanoelectrodeposition. Li ion batteries equipped with the three-dimensional anode demonstrated almost 100% capacity retention over 400 cycles at 450 mA g(-1) and excellent rate performance even up to 9000 mA g(-1) for advanced Li-ion battery. Insight of the high performance can be attributed to three key factors, Li-Sn alloys for Li-ion storage, Ni-Cu matrix for the electronic conductive and nanorods structure, and the carbon shell for the electronic/Li-ion conductive and holding stable solid electrolyte interphase (SEI), because these shells always kept stable volumes after extension of initial charge-discharge cycles. PMID:27113033

  14. Interfacial effects of the Cu2O nano-dots decorated Co3O4 nanorods array and its photocatalytic activity for cleaving organic molecules

    NASA Astrophysics Data System (ADS)

    Qiu, X. P.; Yu, J. S.; Xu, H. M.; Chen, W. X.; Hu, W.; Chen, G. L.

    2016-09-01

    A heterogeneous nanocomposite catalyst constructed by the Co3O4 nanorods decorated with the Cu2O quantum dots (QDs) were successfully synthesized via a simple hydrothermal method followed by an oxidation-reduction processing. The fabricated Cu2O/Co3O4 nanocomposite was characterized by the SEM, TEM, XPS, XRD, UV-vis and PL, and the (2 2 0) and (3 1 1) facets of the Co3O4 were exposed. Compared with the original Co3O4 nanorods with an average diameter of 350 nm, a substantial decrease in the band gap was observed after doping the nanorods with the Cu2O QDs (average diameter of 5 nm). Such a dramatic decrease in the band gap indicated a significant enhancement of the photocatalytic activities under visible light. The methylene blue (MB) dye and the phenol were used as model organic pollutants, and the Cu2O/Co3O4 nanocomposite catalyst exhibited both high catalytic activity and good recycling stability. The catalytic activities of the Cu2O/Co3O4/potassium monopersulfate triple salt (PMS) system for cleaving the MB and the phenol were dependent on the dosages of the Cu2O QDs, and the calculated degradation rates achieved by 7.0 wt% Cu2O/Co3O4 nanocomposite catalyst were about 11.3 and 1.8 times than that of the pristine Co3O4 nanorod catalyst for the MB and the phenol, respectively. The reactive species of rad O2- and the holes were determined to be the main active species for the phenol photocatalytic degradation by the 7 wt% Cu2O/Co3O4/PMS system and the 7 wt% Cu2O/Co3O4/H2O2 system, respectively.

  15. Synergistic effect of dual interfacial modifications with room-temperature-grown epitaxial ZnO and adsorbed indoline dye for ZnO nanorod array/P3HT hybrid solar cell.

    PubMed

    Chen, Dian-Wei; Wang, Ting-Chung; Liao, Wen-Pin; Wu, Jih-Jen

    2013-09-11

    ZnO nanorod (NR)/poly(3-hexylthiophene) (P3HT) hybrid solar cells with interfacial modifications are investigated in this work. The ZnO NR arrays are modified with room-temperature (RT)-grown epitaxial ZnO shells or/and D149 dye molecules prior to the P3HT infiltration. A synergistic effect of the dual modifications on the efficiency of the ZnO NR/P3HT solar cell is observed. The open-circuit voltage and fill factor are considerable improved through the RT-grown ZnO and D149 modifications in sequence on the ZnO NR array, which brings about a 2-fold enhancement of the efficiency of the ZnO NR/P3HT solar cell. We suggested that the more suitable surface of RT-grown ZnO for D149 adsorption, the chemical compatibility of D149 and P3HT, and the elevated conduction band edge of the RT-grown ZnO/D149-modified ZnO NR array construct the superior interfacial morphology and energetics in the RT-grown ZnO/D149-modified ZnO NR/P3HT hybrid solar cell, resulting in the synergistic effect on the cell efficiency. An efficiency of 1.16% is obtained in the RT-grown ZnO/D149-modified ZnO NR/P3HT solar cell. PMID:23937447

  16. Improved Light Extraction Efficiency in Blue Light-Emitting Diodes by SiO2-Coated ZnO Nanorod Arrays

    NASA Astrophysics Data System (ADS)

    Cho, Chu-Young; Kim, Na-Yeong; Kang, Jang-Won; Leem, Young-Chul; Hong, Sang-Hyun; Lim, Wantae; Kim, Sung-Tae; Park, Seong-Ju

    2013-04-01

    We report on the improved light extraction efficiency of blue light-emitting diodes (LEDs) by SiO2-coated ZnO nanorods (NRs) grown on indium-tin oxide (ITO). The optical output power of the LEDs with SiO2-coated ZnO NRs, which are grown on the patterned sapphire substrates, increases by 5% at 20 mA, compared with that of LEDs with bare ZnO NRs. This increase is attributed to the improved light extraction efficiency of LEDs because the SiO2 layer with a refractive index lower than that of ZnO NRs further reduces the Fresnel reflection.

  17. Functionalized ZnO@TiO2 nanorod array film loaded with ZnIn0.25Cu0.02S1.395 solid-solution: synthesis, characterization and enhanced visible light driven water splitting

    NASA Astrophysics Data System (ADS)

    Wang, Ruosong; Xu, Xiaoxue; Zhang, Yi; Chang, Zhimin; Sun, Zaicheng; Dong, Wen-Fei

    2015-06-01

    We have designed a novel semiconductor core/layer nanostructure of a uniform ZnO@TiO2 nanorod array modified with a ZnIn0.25Cu0.02S1.395 solid-solution on the surface via a facile hydrothermal synthesis. This novel nanostructure combines the merits of all components and meets the requirements of photovoltaic system application. An intimate PN heterojunction is formed from the ZnO@TiO2 nanorod and polymetallic sulphide solid-solution, which is remarkably beneficial for the effective visible light absorption and rapid charge carrier separation. The nanostructures exhibit higher photocurrent and incident photon to electron conversion efficiency (IPCE) under no bias potential versus the Ag/AgCl electrode. We also analyzed the interface and photoelectrochemical characteristics of the nanostructure and revealed the kinetic process of the electron and hole transmission. In addition, the photoanode test shows the hydrogen production capability of the nanostructures from solar water splitting. These results verified that the ZnO and TiO2 can be sensitized by the polymetallic sulfide for UV-Vis light driven energy conversion. Importantly, the approach we used to design the photoanode enables the development of micro-nano electronic devices with enhanced performance.We have designed a novel semiconductor core/layer nanostructure of a uniform ZnO@TiO2 nanorod array modified with a ZnIn0.25Cu0.02S1.395 solid-solution on the surface via a facile hydrothermal synthesis. This novel nanostructure combines the merits of all components and meets the requirements of photovoltaic system application. An intimate PN heterojunction is formed from the ZnO@TiO2 nanorod and polymetallic sulphide solid-solution, which is remarkably beneficial for the effective visible light absorption and rapid charge carrier separation. The nanostructures exhibit higher photocurrent and incident photon to electron conversion efficiency (IPCE) under no bias potential versus the Ag/AgCl electrode. We also

  18. High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes.

    PubMed

    Zhou, Lite; Zhao, Chenqi; Giri, Binod; Allen, Patrick; Xu, Xiaowei; Joshi, Hrushikesh; Fan, Yangyang; Titova, Lyubov V; Rao, Pratap M

    2016-06-01

    BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2 (Sb:SnO2) nanorod-arrays (Sb:SnO2/BiVO4 NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest ηabs × ηsep efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a core nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential. PMID:27203779

  19. Electronic Structure Engineering of Cu2O Film/ZnO Nanorods Array All-Oxide p-n Heterostructure for Enhanced Photoelectrochemical Property and Self-powered Biosensing Application

    PubMed Central

    Kang, Zhuo; Yan, Xiaoqin; Wang, Yunfei; Bai, Zhiming; Liu, Yichong; Zhang, Zheng; Lin, Pei; Zhang, Xiaohui; Yuan, Haoge; Zhang, Xueji; Zhang, Yue

    2015-01-01

    We have engineered the electronic structure at the interface between Cu2O and ZnO nanorods (NRs) array, through adjusting the carrier concentration of Cu2O. The electrodeposition of Cu2O at pH 11 acquired the highest carrier concentration, resulting in the largest interfacial electric field between Cu2O and ZnO, which finally led to the highest separation efficiency of photogenerated charge carriers. 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 glutathione (GSH) in PBS buffer even at applied bias of 0 V which made the device self-powered. Besides, the favorable selectivity, high reproducibility and extremely wide detection range, make such heterostructure a promising candidate for PEC biosensing applications, probably for the extended field of PEC water splitting or other solar photovoltaic beacons. PMID:25600940

  20. Electronic structure engineering of Cu2O film/ZnO nanorods array all-oxide p-n heterostructure for enhanced photoelectrochemical property and self-powered biosensing application.

    PubMed

    Kang, Zhuo; Yan, Xiaoqin; Wang, Yunfei; Bai, Zhiming; Liu, Yichong; Zhang, Zheng; Lin, Pei; Zhang, Xiaohui; Yuan, Haoge; Zhang, Xueji; Zhang, Yue

    2015-01-01

    We have engineered the electronic structure at the interface between Cu2O and ZnO nanorods (NRs) array, through adjusting the carrier concentration of Cu2O. The electrodeposition of Cu2O at pH 11 acquired the highest carrier concentration, resulting in the largest interfacial electric field between Cu2O and ZnO, which finally led to the highest separation efficiency of photogenerated charge carriers. 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 glutathione (GSH) in PBS buffer even at applied bias of 0 V which made the device self-powered. Besides, the favorable selectivity, high reproducibility and extremely wide detection range, make such heterostructure a promising candidate for PEC biosensing applications, probably for the extended field of PEC water splitting or other solar photovoltaic beacons. PMID:25600940

  1. Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives

    SciTech Connect

    Ye, XC; Jin, LH; Caglayan, H; Chen, J; Xing, GZ; Zheng, C; Doan-Nguyen, V; Kang, YJ; Engheta, N; Kagan, CR; Murray, CB

    2012-03-01

    We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to similar to 0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR's aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures.

  2. Surface-enhanced Raman spectroscopy in 3D electrospun nanofiber mats coated with gold nanorods.

    PubMed

    Camposeo, Andrea; Spadaro, Donatella; Magrì, Davide; Moffa, Maria; Gucciardi, Pietro G; Persano, Luana; Maragò, Onofrio M; Pisignano, Dario

    2016-02-01

    Nanofibers functionalized by metal nanostructures and particles are exploited as effective flexible substrates for surface-enhanced Raman scattering (SERS) analysis. Their complex three-dimensional structure may provide Raman signals enhanced by orders of magnitude compared to untextured surfaces. Understanding the origin of such improved performances is therefore very important for pushing nanofiber-based analytical technologies to their upper limit. Here, we report on polymer nanofiber mats which can be exploited as substrates for enhancing the Raman spectra of adsorbed probe molecules. The increased surface area and the scattering of light in the nanofibrous system are individually analyzed as mechanisms to enhance Raman scattering. The deposition of gold nanorods on the fibers further amplifies Raman signals due to SERS. This study suggests that Raman signals can be finely tuned in intensity and effectively enhanced in nanofiber mats and arrays by properly tailoring the architecture, composition, and light-scattering properties of the complex networks of filaments. PMID:26670770

  3. Improved size-tunable synthesis of monodisperse gold nanorods through the use of aromatic additives.

    PubMed

    Ye, Xingchen; Jin, Linghua; Caglayan, Humeyra; Chen, Jun; Xing, Guozhong; Zheng, Chen; Doan-Nguyen, Vicky; Kang, Yijin; Engheta, Nader; Kagan, Cherie R; Murray, Christopher B

    2012-03-27

    We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to ~0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR's aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures. PMID:22376005

  4. Enhanced waveguide-type ultraviolet electroluminescence from ZnO/MgZnO core/shell nanorod array light-emitting diodes via coupling with Ag nanoparticles localized surface plasmons

    NASA Astrophysics Data System (ADS)

    Zhang, Cen; Marvinney, Claire Elizabeth; Xu, Hai Yang; Liu, Wei Zhen; Wang, Chun Liang; Zhang, Li Xia; Wang, Jian Nong; Ma, Jian Gang; Liu, Yi Chun

    2014-12-01

    Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ~9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their ``remote'' separation. Thereby, two possible models involving the dynamic process of interactions among excitons, photons, and LSPs, were established to understand the selective enhancement of ZnO EL.Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ~9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their ``remote'' separation

  5. Buffer layer effect on ZnO nanorods growth alignment

    NASA Astrophysics Data System (ADS)

    Zhao, Dongxu; Andreazza, Caroline; Andreazza, Pascal; Ma, Jiangang; Liu, Yichun; Shen, Dezhen

    2005-06-01

    Vertical aligned ZnO nanorods array was fabricated on Si with introducing a ZnO thin film as a buffer layer. Two different nucleation mechanisms were found in growth process. With using Au catalyst, Zn vapor could diffuse into Au nanoclusters with forming a solid solution. Then the ZnO nucleation site is mainly on the catalyst by oxidation of Au/Zn alloy. Without catalyst, nucleation could occur directly on the surface of buffer layer by homoepitaxy. The density and the size of ZnO nanorods could be governed by morphological character of catalyst and buffer layer. The nanorods growth is followed by vapor-solid mechanism.

  6. Spatially branched hierarchical ZnO nanorod-TiO2 nanotube array heterostructures for versatile photocatalytic and photoelectrocatalytic applications: towards intimate integration of 1D-1D hybrid nanostructures.

    PubMed

    Xiao, Fang-Xing; Hung, Sung-Fu; Tao, Hua Bing; Miao, Jianwei; Yang, Hong Bin; Liu, Bin

    2014-12-21

    Hierarchically ordered ZnO nanorods (NRs) decorated nanoporous-layer-covered TiO2 nanotube array (ZnO NRs/NP-TNTAs) nanocomposites have been prepared by an efficient, two-step anodization route combined with an electrochemical deposition strategy, by which monodispersed one-dimensional (1D) ZnO NRs were uniformly grown on the framework of NP-TNTAs. The crystal phases, morphologies, optical properties, photocatalytic as well as photoelectrocatalytic performances of the well-defined ZnO NRs/NP-TNTAs heterostructures were systematically explored to clarify the structure-property correlation. It was found that the ZnO NRs/NP-TNTAs heterostructure exhibits significantly enhanced photocatalytic and photoelectrocatalytic performances, along with favorable photostability toward degradation of organic pollutants under UV light irradiation, as compared to the single component counterparts. The remarkably enhanced photoactivity of ZnO NRs/NP-TNTAs heterostructure is ascribed to the intimate interfacial integration between ZnO NRs and NP-TNTAs substrate imparted by the unique spatially branched hierarchical structure, thereby contributing to the efficient transfer and separation of photogenerated electron-hole charge carriers. Moreover, the specific active species during the photocatalytic process was unambiguously determined and photocatalytic mechanism was tentatively presented. It is anticipated that our work could provide new insights for the construction of various hierarchical 1D-1D hybrid nanocomposites for extensive photocatalytic applications. PMID:25363649

  7. Structural and optical study of core–shell InGaN layers of nanorod arrays with multiple stacks of InGaN/GaN superlattices for absorption of longer solar spectrum

    NASA Astrophysics Data System (ADS)

    Bae, Si-Young; Jung, Byung Oh; Lekhal, Kaddour; Lee, Dong-Seon; Deki, Manato; Honda, Yoshio; Amano, Hiroshi

    2016-05-01

    We report on the material and optical properties of core–shell InGaN layers grown on GaN nanorod arrays. The core–shell InGaN layers were well grown on polarization-reduced surfaces such as semipolar pyramids and nonpolar sidewalls. In addition, to compensate the biaxial strain between GaN and InGaN layers, we grew interlayers underneath a thick InGaN layer. Here, the interlayers were composed of multiple superlattice structures. We could observe that the indium composition of core–shell InGaN structures increased with the number of interlayers. This indicates that the absorption energy band of InGaN alloys can be better matched to the spectral irradiance of the solar spectrum in nature. We also implemented a simulation of Ga-polar and nonpolar InGaN-based solar cells based on the indium composition obtained from the experiments. The result showed that nonpolar InGaN solar cells had a much higher efficiency than Ga-polar InGaN solar cells with the same thickness of the absorption layer.

  8. Enhanced waveguide-type ultraviolet electroluminescence from ZnO/MgZnO core/shell nanorod array light-emitting diodes via coupling with Ag nanoparticles localized surface plasmons.

    PubMed

    Zhang, Cen; Marvinney, Claire Elizabeth; Xu, Hai Yang; Liu, Wei Zhen; Wang, Chun Liang; Zhang, Li Xia; Wang, Jian Nong; Ma, Jian Gang; Liu, Yi Chun

    2015-01-21

    Localized surface plasmon (LSP) enhanced waveguide-type ultraviolet light-emitting diodes (LEDs) were fabricated by sputtering Ag nanoparticles (Ag-NPs) onto ZnO/MgZnO core/shell nanorod array (CS-NRA)/p-GaN heterostructures. A ∼9-fold enhancement of ZnO ultraviolet electroluminescence (EL) was demonstrated by the Ag-NPs decorated LED compared with the device without Ag-NPs. Angle-dependent EL measurements, as well as finite-difference time-domain simulations of the EL intensity spatial distribution, confirmed the waveguide-type EL transmission mode along the NR's axial direction. The increased spontaneous emission rate observed in time-resolved spectroscopy suggested that the ZnO EL enhancement was attributed to LSP-exciton/polariton coupling. However, a direct coupling is very difficult to achieve between Ag-LSPs and electron-hole pairs in the active region due to their "remote" separation. Thereby, two possible models involving the dynamic process of interactions among excitons, photons, and LSPs, were established to understand the selective enhancement of ZnO EL. PMID:25475883

  9. An array of highly flexible electrodes with a tailored configuration locked by gelatin during implantation—initial evaluation in cortex cerebri of awake rats

    PubMed Central

    Agorelius, Johan; Tsanakalis, Fotios; Friberg, Annika; Thorbergsson, Palmi T.; Pettersson, Lina M. E.; Schouenborg, Jens

    2015-01-01

    Background: A major challenge in the field of neural interfaces is to overcome the problem of poor stability of neuronal recordings, which impedes long-term studies of individual neurons in the brain. Conceivably, unstable recordings reflect relative movements between electrode and tissue. To address this challenge, we have developed a new ultra-flexible electrode array and evaluated its performance in awake non-restrained animals. Methods:An array of eight separated gold leads (4 × 10 μm), individually flexible in 3D, were cut from a gold sheet using laser milling and insulated with Parylene C. To provide structural support during implantation into rat cortex, the electrode array was embedded in a hard gelatin based material, which dissolves after implantation. Recordings were made during 3 weeks. At termination, the animals were perfused with fixative and frozen to prevent dislocation of the implanted electrodes. A thick slice of brain tissue, with the electrode array still in situ, was made transparent using methyl salicylate to evaluate the conformation of the implanted electrode array. Results: Median noise levels and signal/noise remained relatively stable during the 3 week observation period; 4.3–5.9 μV and 2.8–4.2, respectively. The spike amplitudes were often quite stable within recording sessions and for 15% of recordings where single-units were identified, the highest-SNR unit had an amplitude higher than 150 μV. In addition, high correlations (>0.96) between unit waveforms recorded at different time points were obtained for 58% of the electrode sites. The structure of the electrode array was well preserved 3 weeks after implantation. Conclusions: A new implantable multichannel neural interface, comprising electrodes individually flexible in 3D that retain its architecture and functionality after implantation has been developed. Since the new neural interface design is adaptable, it offers a versatile tool to explore the function of various brain

  10. Graded core/shell semiconductor nanorods and nanorod barcodes

    DOEpatents

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2010-12-14

    Graded core/shell semiconductor nanorods and shaped nanorods are disclosed comprising Group II-VI, Group III-V and Group IV semiconductors and methods of making the same. Also disclosed are nanorod barcodes using core/shell nanorods where the core is a semiconductor or metal material, and with or without a shell. Methods of labeling analytes using the nanorod barcodes are also disclosed.

  11. Graded core/shell semiconductor nanorods and nanorod barcodes

    DOEpatents

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2013-03-26

    Graded core/shell semiconductor nanorods and shapped nanorods are disclosed comprising Group II-VI, Group III-V and Group IV semiconductors and methods of making the same. Also disclosed are nanorod barcodes using core/shell nanorods where the core is a semiconductor or metal material, and with or without a shell. Methods of labeling analytes using the nanorod barcodes are also disclosed.

  12. Charge collection enhancement by incorporation of gold-silica core-shell nanoparticles into P3HT:PCBM/ZnO nanorod array hybrid solar cells.

    PubMed

    Wang, Ting-Chung; Su, Yen-Hsun; Hung, Yun-Kai; Yeh, Chen-Sheng; Huang, Li-Wen; Gomulya, Widianta; Lai, Lai-Hung; Loi, Maria A; Yang, Jih-Sheng; Wu, Jih-Jen

    2015-08-14

    In this work, gold-silica core-shell (Au@silica) nanoparticles (NPs) with various silica-shell thicknesses are incorporated into P3HT:PCBM/ZnO nanorod (NR) hybrid solar cells. Enhancement in the short-circuit current density and the efficiency of the hybrid solar cells is attained with the appropriate addition of Au@silica NPs regardless of the silica-shell thickness. Compared to the P3HT:PCBM/ZnO NR hybrid solar cell, a 63% enhancement in the efficiency is achieved by the P3HT:PCBM/Au@silica NP/ZnO NR hybrid solar cell. The finite difference time domain simulations indicate that the strength of the Fano resonance, i.e., the electric field of the quasi-static asymmetric quadrupole, on the surface of Au@silica NPs in the P3HT:PCBM/ZnO NR hybrid significantly decreases with increasing thickness of the silica shell. Raman characterization reveals that the degree of P3HT order increases when Au@silica NPs are incorporated into the P3HT:PCBM/ZnO NR hybrid. The charge separation at the interface between P3HT and PCBM as well as the electron transport in the active layer are retarded by the electric field of the Fano resonance. Nevertheless, the prolongation of the electron lifetime and the reduction of the electron transit time in the P3HT:PCBM/ZnO NR hybrid solar cells, which result in an enhancement of electron collection, are achieved by the addition of Au@silica NPs. This may be attributed to the improvement in the degree of P3HT order and connectivity of PCBM when Au@silica NPs are incorporated into the P3HT:PCBM active layer. PMID:26159896

  13. Effects of electrical and optical properties of thickness condition of ZnO nanorod array layer for efficient electrochemical luminescence cell device

    NASA Astrophysics Data System (ADS)

    Choi, Hye Su; Chansri, Pakpoom; Sung, Youl Moon

    2016-02-01

    In this paper, we report on electrochemical luminescence (ECL) cells with a ZnO nanorod (ZNR) layer. The investigated ECL cells were composed of F-doped SnO2 (FTO) glass/Ru(II)/ZNRs/FTO glass, which used a ZNR layer as an electrode and the Ru(II) complex [Ru(bpy)32+] as a light-emitting material. The ECL cells were fabricated by changing the thickness of ZNRs from 5 to 12.5 µm. The luminescence property of the ECL cells was strongly affected by the variation in the thickness of the ZNR layer. The threshold voltage for the light emission from the ECL cells was 2 V for 10 µm thick ZNRs, which was lower than that of the thickness of the ECL cells without a ZNR layer. Also, the intensity of luminance from the ECL cells with ZNRs was much higher than that from the ECL cells without ZNRs at the same operating voltage. The efficiency of the ECL cells without ZNRs measured at 3 V was 0.0049 lm/W, while those of the ECL cells with ZNRs were 0.0121, 0.0157, 0.0354, and 0.024 lm/W for the ZNRs layer thicknesses 5, 7.5, 10, and 12.5 µm, respectively. However, the peak light intensity at the wavelength was 623 nm which had not affected the all ZNRs thicknesses. The best lifetime of the ECL cells with these thicknesses was 40 min for ZNRs 10 µm. The use of the ZNR layer in the ECL cells significantly improves the luminescence performance.

  14. Nanorods of Co/Pd multilayers fabricated by glancing angle deposition for advanced media

    NASA Astrophysics Data System (ADS)

    Su, Hao; Natarajarathinam, Anusha; Gupta, Subhadra

    2013-05-01

    Perpendicular anisotropy magnetic nanorods composed of Co/Pd multilayers have been successfully fabricated by glancing angle deposition (GLAD) in a planetary sputtering system. Co and Pd layer thickness, ratio, and bilayer number were optimized for both normal and GLAD depositions. Scanning electron micrographs estimated the nanorods to be about 12 nm in diameter. M-H loops showed that the coercivity for the GLAD nanorods increased from 1.3 kOe for the normally deposited continuous films to 2.9 kOe for the GLAD nanorod array, a 123% increase.

  15. Nanorods of Co/Pd multilayers fabricated by glancing angle deposition for advanced media

    SciTech Connect

    Su, Hao; Gupta, Subhadra; Natarajarathinam, Anusha

    2013-05-28

    Perpendicular anisotropy magnetic nanorods composed of Co/Pd multilayers have been successfully fabricated by glancing angle deposition (GLAD) in a planetary sputtering system. Co and Pd layer thickness, ratio, and bilayer number were optimized for both normal and GLAD depositions. Scanning electron micrographs estimated the nanorods to be about 12 nm in diameter. M-H loops showed that the coercivity for the GLAD nanorods increased from 1.3 kOe for the normally deposited continuous films to 2.9 kOe for the GLAD nanorod array, a 123% increase.

  16. Nanocap arrays of granular CoCrPt:SiO2 films on silica particles: tailoring of the magnetic properties by Co+ irradiation.

    PubMed

    Krone, P; Brombacher, C; Makarov, D; Lenz, K; Ball, D; Springer, F; Rohrmann, H; Fassbender, J; Albrecht, M

    2010-09-24

    An approach for tailoring the magnetic properties by ion irradiation of granular perpendicular CoCrPt:SiO(2) films grown on silica particles with sizes down to 10 nm was investigated. The as-prepared samples reveal an intriguing scaling dependence of the coercive field and remnant magnetization: both parameters are found to decrease with decreasing particle size. However, Co(+) irradiation at a low fluence of 0.5 x 10(14) cm(-2) already results in an opposite scaling behavior. It is assumed that this modification is due to the enhancement of the intergranular magnetic exchange coupling of the granular CoCrPt:SiO(2) film initiated by Co(+) irradiation resulting in a modified reversal behavior. Further increase of the irradiation fluence beyond 1.6 x 10(14) ions cm(-2) leads to a degradation of the magnetic layer properties, lowering the remnant magnetization and the coercive field in the easy-axis direction. Moreover, the local magnetic properties of the samples were analyzed by magnetic force microscopy revealing magnetic multi-domain cap structures. PMID:20798462

  17. Nanocap arrays of granular CoCrPt:SiO2 films on silica particles: tailoring of the magnetic properties by Co + irradiation

    NASA Astrophysics Data System (ADS)

    Krone, P.; Brombacher, C.; Makarov, D.; Lenz, K.; Ball, D.; Springer, F.; Rohrmann, H.; Fassbender, J.; Albrecht, M.

    2010-09-01

    An approach for tailoring the magnetic properties by ion irradiation of granular perpendicular CoCrPt:SiO2 films grown on silica particles with sizes down to 10 nm was investigated. The as-prepared samples reveal an intriguing scaling dependence of the coercive field and remnant magnetization: both parameters are found to decrease with decreasing particle size. However, Co + irradiation at a low fluence of 0.5 × 1014 cm - 2 already results in an opposite scaling behavior. It is assumed that this modification is due to the enhancement of the intergranular magnetic exchange coupling of the granular CoCrPt:SiO2 film initiated by Co + irradiation resulting in a modified reversal behavior. Further increase of the irradiation fluence beyond 1.6 × 1014 ions cm - 2 leads to a degradation of the magnetic layer properties, lowering the remnant magnetization and the coercive field in the easy-axis direction. Moreover, the local magnetic properties of the samples were analyzed by magnetic force microscopy revealing magnetic multi-domain cap structures.

  18. Colloidal luminescent silicon nanorods.

    PubMed

    Lu, Xiaotang; Hessel, Colin M; Yu, Yixuan; Bogart, Timothy D; Korgel, Brian A

    2013-07-10

    Silicon nanorods are grown by trisilane decomposition in hot squalane in the presence of tin (Sn) nanocrystals and dodecylamine. Sn induces solution-liquid-solid nanorod growth with dodecylamine serving as a stabilizing ligand. As-prepared nanorods do not luminesce, but etching with hydrofluoric acid to remove residual surface oxide followed by thermal hydrosilylation with 1-octadecene induces bright photoluminescence with quantum yields of 4-5%. X-ray photoelectron spectroscopy shows that the ligands prevent surface oxidation for months when stored in air. PMID:23731184

  19. Shape-induced separation of nanospheres and aligned nanorods.

    PubMed

    Ahmad, I; Zandvliet, H J W; Kooij, E S

    2014-07-15

    We studied the phase separation and spatial arrangement of gold nanorods and nanospheres after evaporative self-assembly from aqueous suspension. Depending on the position relative to the contact line of the drying droplet, spheres and rods separate into various liquid-crystalline phases. Nanorods exhibit a strong preference for side-by-side alignment, giving rise to smectic phases; spheres in solution are forced out of these regions and form close-packed arrays. We discuss this self-separation into nanorod- and sphere-rich phases in terms of various interactions, including electrostatic, van der Waals, and deplection interactions forces. The experimental results are compared to quantitative calculations of the colloidal interaction energies. We also describe and discuss the role of the surfactant on the different crystal facets of the nanorods on the assembly process. PMID:24959664

  20. Highly tunable gold nanorod dimer resonances mediated through conductive junctions

    NASA Astrophysics Data System (ADS)

    Fontana, Jake; Ratna, Banahalli

    2015-03-01

    Tailoring the resonant frequency in plasmonic nanostructures is critical to developing disruptive metamaterial technologies. Here we numerically study the optical properties of gold nanorod dimers connected end-to-end by a thin metallic bridge. We find the resonant frequency along the long axis of the dimer shifts linearly with the nanorod aspect ratio behaving as it was a single nanorod with an aspect ratio nearly an order of magnitude larger. We show by controlling the material and geometry of the connecting bridge the effective depolarization factor of the dimer is significantly modulated tuning the resonant frequency over a decade, from 1 to 10 μm. We present an alternative description for the emergence and behavior of the dimer resonance using a straightforward ``Drude-like'' model and self-assembly experiments creating such structures.

  1. Optical forces in nanorod metamaterial

    PubMed Central

    Bogdanov, Andrey A.; Shalin, Alexander S.; Ginzburg, Pavel

    2015-01-01

    Optomechanical manipulation of micro and nano-scale objects with laser beams finds use in a large span of multidisciplinary applications. Auxiliary nanostructuring could substantially improve performances of classical optical tweezers by means of spatial localization of objects and intensity required for trapping. Here we investigate a three-dimensional nanorod metamaterial platform, serving as an auxiliary tool for the optical manipulation, able to support and control near-field interactions and generate both steep and flat optical potential profiles. It was shown that the ‘topological transition’ from the elliptic to hyperbolic dispersion regime of the metamaterial, usually having a significant impact on various light-matter interaction processes, does not strongly affect the distribution of optical forces in the metamaterial. This effect is explained by the predominant near-fields contributions of the nanostructure to optomechanical interactions. Semi-analytical model, approximating the finite size nanoparticle by a point dipole and neglecting the mutual re-scattering between the particle and nanorod array, was found to be in a good agreement with full-wave numerical simulation. In-plane (perpendicular to the rods) trapping regime, saddle equilibrium points and optical puling forces (directed along the rods towards the light source), acting on a particle situated inside or at the nearby the metamaterial, were found. PMID:26514667

  2. Eight-channel transceiver RF coil array tailored for ¹H/¹⁹F MR of the human knee and fluorinated drugs at 7.0 T.

    PubMed

    Ji, Yiyi; Waiczies, Helmar; Winter, Lukas; Neumanova, Pavla; Hofmann, Daniela; Rieger, Jan; Mekle, Ralf; Waiczies, Sonia; Niendorf, Thoralf

    2015-06-01

    The purpose of this study was to evaluate the feasibility of an eight-channel dual-tuned transceiver surface RF coil array for combined (1)H/(19)F MR of the human knee at 7.0 T following application of (19)F-containing drugs. The (1)H/(19)F RF coil array includes a posterior module with two (1)H loop elements and two anterior modules, each consisting of one (1)H and two (19)F elements. The decoupling of neighbor elements is achieved by a shared capacitor. Electromagnetic field simulations were performed to afford uniform transmission fields and to be in accordance with RF safety guidelines. Localized (19)F MRS was conducted with 47 and 101 mmol/L of flufenamic acid (FA) – a (19)F-containing non-steroidal anti-inflammatory drug – to determine T1 and T2 and to study the (19)F signal-to-dose relationship. The suitability of the proposed approach for (1)H/(19)F MR was examined in healthy subjects. Reflection coefficients of each channel were less than -17 dB and coupling between channels was less than -11 dB. Q(L)/Q(U) was less than 0.5 for all elements. MRS results demonstrated signal stability with 1% variation. T1 and T2 relaxation times changed with concentration of FA: T1 /T2 = 673/31 ms at 101 mmol/L and T1 /T2 = 616/26 ms at 47 mmol/L. A uniform signal and contrast across the patella could be observed in proton imaging. The sensitivity of the RF coil enabled localization of FA ointment administrated to the knee with an in-plane spatial resolution of (1.5 × 1.5) mm(2) achieved in a total scan time of approximately three minutes, which is well suited for translational human studies. This study shows the feasibility of combined (1)H/(19)F MRI of the knee at 7.0 T and proposes T1 and T2 mapping methods for quantifying fluorinated drugs in vivo. Further technological developments are necessary to promote real-time bioavailability studies and quantification of (19)F-containing medicinal compounds in vivo. PMID:25916199

  3. Effective PEGylation of gold nanorods

    NASA Astrophysics Data System (ADS)

    Schulz, F.; Friedrich, W.; Hoppe, K.; Vossmeyer, T.; Weller, H.; Lange, H.

    2016-03-01

    Standard procedures to coat gold nanorods (AuNR) with poly(ethylene glycol) (PEG)-based ligands are not reliable and high PEG-grafting densities are not achieved. In this work, the ligand exchange of AuNR with PEGMUA, a tailored PEG-ligand bearing a C10 alkylene spacer, is studied. PEGMUA provides AuNR with very high stability against oxidative etching with cyanide. This etching reaction is utilized to study the ligand exchange in detail. Ligand exchange is faster, less ligand consuming and more reproducible with assisting chloroform extraction. Compared to PEG ligands commonly used, PEGMUA provides much higher colloidal and chemical stability. Further analyses based on NMR-, IR- and UV/Vis-spectroscopy reveal that significantly higher PEG-grafting densities, up to ~3 nm-2, are obtained with PEGMUA. This demonstrates how the molecular structure of the PEG ligand can be used to dramatically improve the ligand exchange and to synthesize PEGylated AuNR with high chemical and colloidal stability and high PEG grafting densities. Such AuNR are especially interesting for applications in nanomedicine.Standard procedures to coat gold nanorods (AuNR) with poly(ethylene glycol) (PEG)-based ligands are not reliable and high PEG-grafting densities are not achieved. In this work, the ligand exchange of AuNR with PEGMUA, a tailored PEG-ligand bearing a C10 alkylene spacer, is studied. PEGMUA provides AuNR with very high stability against oxidative etching with cyanide. This etching reaction is utilized to study the ligand exchange in detail. Ligand exchange is faster, less ligand consuming and more reproducible with assisting chloroform extraction. Compared to PEG ligands commonly used, PEGMUA provides much higher colloidal and chemical stability. Further analyses based on NMR-, IR- and UV/Vis-spectroscopy reveal that significantly higher PEG-grafting densities, up to ~3 nm-2, are obtained with PEGMUA. This demonstrates how the molecular structure of the PEG ligand can be used to

  4. Ultrasensitive, Real-time and Discriminative Detection of Improvised Explosives by Chemiresistive Thin-film Sensory Array of Mn(2+) Tailored Hierarchical ZnS.

    PubMed

    Zhou, Chaoyu; Wu, Zhaofeng; Guo, Yanan; Li, Yushu; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

    2016-01-01

    A simple method combing Mn(2+) doping with a hierarchical structure was developed for the improvement of thin-film sensors and efficient detection of the explosives relevant to improvised explosive devices (IEDs). ZnS hierarchical nanospheres (HNs) were prepared via a solution-based route and their sensing performances were manipulated by Mn(2+) doping. The responses of the sensors based on ZnS HNs towards 8 explosives generally increase firstly and then decrease with the increase of the doped Mn(2+) concentration, reaching the climate at 5% Mn(2+). Furthermore, the sensory array based on ZnS HNs with different doping levels achieved the sensitive and discriminative detection of 6 analytes relevant to IEDs and 2 military explosives in less than 5 s at room temperature. Importantly, the superior sensing performances make ZnS HNs material interesting in the field of chemiresistive sensors, and this simple method could be a very promising strategy to put the sensors based on thin-films of one-dimensional (1D) nanostructures into practical IEDs detection. PMID:27161193

  5. Ultrasensitive, Real-time and Discriminative Detection of Improvised Explosives by Chemiresistive Thin-film Sensory Array of Mn2+ Tailored Hierarchical ZnS

    NASA Astrophysics Data System (ADS)

    Zhou, Chaoyu; Wu, Zhaofeng; Guo, Yanan; Li, Yushu; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

    2016-05-01

    A simple method combing Mn2+ doping with a hierarchical structure was developed for the improvement of thin-film sensors and efficient detection of the explosives relevant to improvised explosive devices (IEDs). ZnS hierarchical nanospheres (HNs) were prepared via a solution-based route and their sensing performances were manipulated by Mn2+ doping. The responses of the sensors based on ZnS HNs towards 8 explosives generally increase firstly and then decrease with the increase of the doped Mn2+ concentration, reaching the climate at 5% Mn2+. Furthermore, the sensory array based on ZnS HNs with different doping levels achieved the sensitive and discriminative detection of 6 analytes relevant to IEDs and 2 military explosives in less than 5 s at room temperature. Importantly, the superior sensing performances make ZnS HNs material interesting in the field of chemiresistive sensors, and this simple method could be a very promising strategy to put the sensors based on thin-films of one-dimensional (1D) nanostructures into practical IEDs detection.

  6. Ultrasensitive, Real-time and Discriminative Detection of Improvised Explosives by Chemiresistive Thin-film Sensory Array of Mn2+ Tailored Hierarchical ZnS

    PubMed Central

    Zhou, Chaoyu; Wu, Zhaofeng; Guo, Yanan; Li, Yushu; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

    2016-01-01

    A simple method combing Mn2+ doping with a hierarchical structure was developed for the improvement of thin-film sensors and efficient detection of the explosives relevant to improvised explosive devices (IEDs). ZnS hierarchical nanospheres (HNs) were prepared via a solution-based route and their sensing performances were manipulated by Mn2+ doping. The responses of the sensors based on ZnS HNs towards 8 explosives generally increase firstly and then decrease with the increase of the doped Mn2+ concentration, reaching the climate at 5% Mn2+. Furthermore, the sensory array based on ZnS HNs with different doping levels achieved the sensitive and discriminative detection of 6 analytes relevant to IEDs and 2 military explosives in less than 5 s at room temperature. Importantly, the superior sensing performances make ZnS HNs material interesting in the field of chemiresistive sensors, and this simple method could be a very promising strategy to put the sensors based on thin-films of one-dimensional (1D) nanostructures into practical IEDs detection. PMID:27161193

  7. Watching single gold nanorods grow.

    PubMed

    Wei, Zhongqing; Qi, Hua; Li, Min; Tang, Bochong; Zhang, Zhengzheng; Han, Ruiling; Wang, Jiaojiao; Zhao, Yuliang

    2012-05-01

    The consecutive evolution process of single gold nanorods is monitored using atomic force microscopy (AFM). The single-crystal gold nanorods investigated are grown directly on surfaces to which gold seed particles are covalently linked. The growth kinetics for single nanorods is derived from the 3D information recorded by AFM. A better understanding of the seed-mediated growth mechanism may ultimately lead to the direct growth of aligned nanorods on surfaces. PMID:22378704

  8. Photoactive area modification in bulk heterojunction organic solar cells using optimization of electrochemically synthesized ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Mehdi, Ahmadi; Sajjad Rashidi, Dafeh

    2015-11-01

    In this work, ZnO nanorod arrays grown by an electrochemical deposition method are investigated. The crucial parameters of length, diameter, and density of the nanorods are optimized over the synthesize process and nanorods growth time. Crystalline structure, morphologies, and optical properties of ZnO nanorod arrays are studied by different techniques such as x-ray diffraction, scanning electron microscope, atomic force microscope, and UV-visible transmission spectra. The ZnO nanorod arrays are employed in an inverted bulk heterojunction organic solar cell of Poly (3-hexylthiophene):[6-6] Phenyl-(6) butyric acid methyl ester to introduce more surface contact between the electron transporter layer and the active layer. Our results show that the deposition time is a very important factor to achieve the aligned and uniform ZnO nanorods with suitable surface density which is required for effective infiltration of active area into the ZnO nanorod spacing and make a maximum interfacial surface contact for electron collection, as overgrowing causes nanorods to be too dense and thick and results in high resistance and lower visible light transmittance. By optimizing the thickness of the active layer on top of ZnO nanorods, an improved efficiency of 3.17% with a high FF beyond 60% was achieved.

  9. Growth of vertically aligned ZnO nanorods using textured ZnO films

    PubMed Central

    2011-01-01

    A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.) PMID:21899743

  10. Effective PEGylation of gold nanorods.

    PubMed

    Schulz, F; Friedrich, W; Hoppe, K; Vossmeyer, T; Weller, H; Lange, H

    2016-04-01

    Standard procedures to coat gold nanorods (AuNR) with poly(ethylene glycol) (PEG)-based ligands are not reliable and high PEG-grafting densities are not achieved. In this work, the ligand exchange of AuNR with PEGMUA, a tailored PEG-ligand bearing a C10 alkylene spacer, is studied. PEGMUA provides AuNR with very high stability against oxidative etching with cyanide. This etching reaction is utilized to study the ligand exchange in detail. Ligand exchange is faster, less ligand consuming and more reproducible with assisting chloroform extraction. Compared to PEG ligands commonly used, PEGMUA provides much higher colloidal and chemical stability. Further analyses based on NMR-, IR- and UV/Vis-spectroscopy reveal that significantly higher PEG-grafting densities, up to ∼3 nm(-2), are obtained with PEGMUA. This demonstrates how the molecular structure of the PEG ligand can be used to dramatically improve the ligand exchange and to synthesize PEGylated AuNR with high chemical and colloidal stability and high PEG grafting densities. Such AuNR are especially interesting for applications in nanomedicine. PMID:26975977

  11. Gold Nanobipyramid-Directed Growth of Length-Variable Silver Nanorods with Multipolar Plasmon Resonances.

    PubMed

    Zhuo, Xiaolu; Zhu, Xingzhong; Li, Qian; Yang, Zhi; Wang, Jianfang

    2015-07-28

    We report on a method for the preparation of uniform and length-variable Ag nanorods through anisotropic Ag overgrowth on high-purity Au nanobipyramids. The rod diameters can be roughly tailored from ∼20 nm to ∼50 nm by judicious selection of differently sized Au nanobipyramids. The rod lengths can be tuned from ∼150 nm to ∼550 nm by varying the Ag precursor amount during the overgrowth process and/or by anisotropic shortening through mild oxidation. The controllable aspect ratios, high purity, and high dimensional uniformity of these Ag nanorods enable the observation of Fabry-Pérot-like multipolar plasmon resonance modes in the colloidal suspensions at the ensemble level, which has so far been demonstrated only on Au nanorods prepared electrochemically with anodic aluminum oxide templates. Depending on the mode order and geometry of the Ag nanorods, the multipolar plasmon wavelengths can be readily tailored over a wide spectral range from the visible to near-infrared region. We have further elucidated the relationships between the multipolar plasmon wavelengths and the geometric dimensions of the Ag nanorods at both the ensemble and single-particle levels. Our results indicate that the Au nanobipyramid-directed, dimensionally controllable Ag nanorods will be an attractive and promising candidate for developing multipolar plasmon-based devices and applications. PMID:26135608

  12. Facile fabrication of rutile monolayer films consisting of well crystalline nanorods by following an IL-assisted hydrothermal route

    SciTech Connect

    Peng Peng; Liu Xiaodi; Sun, Chuansheng; Ma Jianmin; Zheng Wenjun

    2009-05-15

    In this study, rutile films consisting of rectangular nanorods were facilely deposited on glass substrates from strongly acid solution of TiCl{sub 4}. The highly ordered array of nanorods was realized in presence of ionic liquid (IL) of [Bmim]Br by following a hydrothermal process. In this process, Degussa P25 nanoparticles served as seeds that were pre-deposited on the substrates to facilitate the array of rutile nanorods. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectrum were used to characterize the obtained nanorod films. The measurements showed that the nanorods were rectangular with width of 100-200 nm and length of more than 1 {mu}m, and grew up typically along c-axis to form the arrays against the substrate. The presence of IL was found vital for the formation of rutile nanorods, and the suitable molar ratio of [Bmim]Br to TiCl{sub 4} ranged from 500:1 to 1500:1. The excessive [Bmim]Br may hinder the precipitation of rutile particles. - Graphical abstract: The rutile film consisting of rectangular nanorods is successfully deposited on glass substrate in presence of ionic liquid (IL) of [Bmim]Br. The nanorods were rectangular with width of 100-200 nm and length of more than 1 {mu}m, which grew up typically along c-axis to form the arrays against the substrate.

  13. Effect of thicknesses of copper catalyst and oxide sublayer on morphology of ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Lyanguzov, N. V.; Kaydashev, V. E.; Kaidashev, E. M.; Abdulvakhidov, K. G.

    2011-03-01

    The influence of thicknesses of a ZnO sublayer and a copper catalyst film on the morphology of ZnO nanorods grown by carbothermal synthesis on α-Al2O3(11-20) substrates has been studied. An increase in the Cu catalyst film thickness leads to a growth in the diameters, heights, and surface density of nanorods. As the ZnO sublayer thickness is increased, the average diameter of nanorods also increases, while their lengths and surface density decrease. The effect of elevated temperatures on the thermal decomposition of ultrathin Cu films deposited on α-Al2O3 substrates has been studied. The photoluminescence characteristics of nanorod arrays have been measured at high levels of optical pumping. An increase in the pumping level to 250-280 kW/cm2 leads to superluminescence of the nanorods.

  14. Synthesis of Absorption-Dominant Small Gold Nanorods and Their Plasmonic Properties.

    PubMed

    Jia, Henglei; Fang, Caihong; Zhu, Xiao-Ming; Ruan, Qifeng; Wang, Yi-Xiang J; Wang, Jianfang

    2015-07-01

    Absorption-dominant small Au nanorods with diameters of less than 10 nm are prepared using a facile seed-mediated growth method. The diameters of the small gold nanorods range from 6 to 9 nm, and their lengths vary from 16 to 45 nm. Their aspect ratios can be tailored from 2.7 to 4.7. As a result, the longitudinal plasmon resonance wavelengths are readily tunable from ∼720 nm to ∼830 nm by changing the seed-to-Au(III) molar ratio in the growth solution. The fractions of the scattering in the total extinction of the small Au nanorods are found to be in the range of 0.005 to 0.025 with finite-difference time-domain simulations, confirming that the extinction values of these small Au nanorods are dominantly contributed to by the light absorption. Moreover, the small Au nanorod sample is coated with a dense silica layer for photothermal therapy with three cell lines. It shows improved photothermal therapy performance compared to a large Au nanorod sample for the same cellular Au contents. Our study suggests that small Au nanorods are promising light absorbers and photothermal therapy agents. PMID:26079391

  15. Laser stimulated electrooptics in the Ag-ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Tan, Sin Tee; AlZayed, N. S.; Lakshminarayana, G.; Naumar, F.; Umar, A. A.; Oyama, M.; Myronchuk, G.; Kityk, I. V.

    2014-07-01

    In the present work, we have discovered a photoinduced linear electrooptics in ZnO nanorods which were fabricated by simply varying the content of the growth solution. It was established that by varying the growth solution concentration one can vary the surface density of the ZnO nanorod arrays growth on the surface. The lowest ZnO content produces the lowest surface density in the nanorods. The photoinduced linear electrooptics was studied using the He-Ne laser at wavelength 1150 nm and was stimulated by 7 ns nitrogen laser at 371 nm. The nonlinear dependence of the Ag nanoparticle (NP) concentration was found and it was significantly higher than that for the pure ZnO NP. Principal role of the Ag NP on the observed effects was discussed.

  16. Investigating the optical XNOR gate using plasmonic nano-rods

    NASA Astrophysics Data System (ADS)

    Akhlaghi, Majid; Kaboli, Milad

    2016-04-01

    In this paper, a coherent perfect absorption (CPA)-type XNOR gate based on plasmonic nano particle is proposed. It consists of two plasmonic nano rod arrays on top of two parallel arms with quartz substrate. The operation principle is based on the absorbable formation of a conductive path in the dielectric layer of a plasmonic nano-particles waveguide. Since the CPA efficiency depends strongly on the number of plasmonic nano-rod and the nano rod location, an efficient binary optimization method based the Particle Swarm Optimization (PSO) algorithm is used to design an optimized array of the plasmonic nano-rod in order to achieve the maximum absorption coefficient in the 'off' state and the minimum absorption coefficient in the 'on' state. In Binary PSO (BPSO), a group of birds consists a matrix with binary entries, control the presence ('1‧) or the absence ('0‧) of nano rod in the array.

  17. Directed self-assembly of nanorod networks: bringing the top down to the bottom up.

    PubMed

    Einsle, Joshua F; Scheunert, Gunther; Murphy, Antony; McPhillips, John; Zayats, Anatoly V; Pollard, Robert; Bowman, Robert M

    2012-12-21

    Self-assembled electrodeposited nanorod materials have been shown to offer an exciting landscape for a wide array of research ranging from nanophotonics through to biosensing and magnetics. However, until now, the scope for site-specific preparation of the nanorods on wafers has been limited to local area definition. Further there is little or no lateral control of nanorod height. In this work we present a scalable method for controlling the growth of the nanorods in the vertical direction as well as their lateral position. A focused ion beam pre-patterns the Au cathode layer prior to the creation of the anodized aluminium oxide (AAO) template on top. When the pre-patterning is of the same dimension as the pore spacing of the AAO template, lines of single nanorods are successfully grown. Further, for sub-200 nm wide features, a relationship between the nanorod height and distance from the non-patterned cathode can be seen to follow a quadratic growth rate obeying Faraday's law of electrodeposition. This facilitates lateral control of nanorod height combined with localized growth of the nanorods. PMID:23183100

  18. Photochemical synthesis of gold nanorods.

    PubMed

    Kim, Franklin; Song, Jae Hee; Yang, Peidong

    2002-12-01

    Gold nanorods have been synthesized by photochemically reducing gold ions within a micellar solution. The aspect ratio of the rods can be controlled with the addition of silver ions. This process reported here is highly promising for producing uniform nanorods, and more importantly it will be useful in resolving the growth mechanism of anisotropic metal nanoparticles due to its simplicity and the relatively slow growth rate of the nanorods. PMID:12452700

  19. Highly efficient yttrium-doped ZnO nanorods for quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Soo-Kyoung; Gopi, Chandu V. V. M.; Srinivasa Rao, S.; Punnoose, Dinah; Kim, Hee-Je

    2016-03-01

    Yttrium-doped ZnO nanorod arrays were applied to photoanodes of quantum dot-sensitized solar cells (QDSCs). The introduction of yttrium to ZnO nanostructures facilitates the growth of ZnO nanorods and increases the amount of QD deposition with a large surface area. Furthermore, lower electrical resistance and longer electron lifetime were achieved with yttrium-doping owing to fewer defects and trap sites on the surface of yttrium-doped ZnO nanorods. As a result, the conversion efficiency of 3.3% was achieved with the optimized concentration of yttrium.

  20. Vertically aligned self-assembled gold nanorods as low turn-on, stable field emitters

    NASA Astrophysics Data System (ADS)

    Apte, Amey; Joshi, Padmashree; Bhaskar, Prashant; Joag, Dilip; Kulkarni, Sulabha

    2015-11-01

    In this work we have investigated field emission from self-assembled, vertically aligned, gold nanorod arrays, which were synthesized via a colloidal growth method. A field emission current density of ∼1 mA/cm2 was measured for these gold nanorod arrays using an anode-cathode separation of ∼3.5 mm. The field emission investigation of these gold nanorod arrays was carried out at a base pressure of ∼10-8 mbar. The turn on field, defined as the electric field required to obtain a current density of 1 μA/cm2, is observed to be 1.9 V/μm. Assuming a work function value of 5.3 eV, the field enhancement factor β is estimated to be ∼2931, which is higher than the reported values for other gold nanostructures/arrays.

  1. Tailored Porous Materials

    SciTech Connect

    BARTON,THOMAS J.; BULL,LUCY M.; KLEMPERER,WALTER G.; LOY,DOUGLAS A.; MCENANEY,BRIAN; MISONO,MAKOTO; MONSON,PETER A.; PEZ,GUIDO; SCHERER,GEORGE W.; VARTULI,JAMES C.; YAGHI,OMAR M.

    1999-11-09

    Tailoring of porous materials involves not only chemical synthetic techniques for tailoring microscopic properties such as pore size, pore shape, pore connectivity, and pore surface reactivity, but also materials processing techniques for tailoring the meso- and the macroscopic properties of bulk materials in the form of fibers, thin films and monoliths. These issues are addressed in the context of five specific classes of porous materials: oxide molecular sieves, porous coordination solids, porous carbons, sol-gel derived oxides, and porous heteropolyanion salts. Reviews of these specific areas are preceded by a presentation of background material and review of current theoretical approaches to adsorption phenomena. A concluding section outlines current research needs and opportunities.

  2. Growth and characterization of vertically aligned ZnO nanorods grown on porous silicon: Effect of precursor concentration

    NASA Astrophysics Data System (ADS)

    Shabannia, R.; Abu Hassan, H.

    2013-10-01

    Vertically aligned ZnO nanorods were successfully synthesized on porous silicon (PS) substrates by chemical bath deposition method at low temperature. The effect of precursor concentration on the growth of ZnO nanorods were systematically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), low and high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and Raman spectroscopy. The XRD results reveal that all the as-grown ZnO nanorod arrays grew preferentially oriented along the c-axis with a hexagonal wurtzite structure. The FESEM images show that the ZnO nanorods grown perpendicular to the PS substrates had diameters and lengths ranging from 13 nm to 69 nm and from 85 nm to 208 nm, respectively. The low-resolution TEM image indicates that the ZnO nanorod arrays had a uniform diameter along their whole length and a smooth surface. PL and Raman analyses reveal that the aligned ZnO nanorods exhibited a sharp ultraviolet peak and high E2 (high) at around 390 nm and 433.8 cm-1, respectively. Furthermore, the ZnO nanorods grew vertically under 0.050 M precursor concentration, resulting in a high structural and optical quality. These ZnO nanorods can be potentially used for fabricating nanoelectronic and nano-optical devices.

  3. Semiconductor nanorod liquid crystals

    SciTech Connect

    Li, Liang-shi; Walda, Joost; Manna, Liberato; Alivisatos, A. Paul

    2002-01-28

    Rodlike molecules form liquid crystalline phases with orientational order and positional disorder. The great majority of materials in which liquid crystalline phases have been observed are comprised of organic molecules or polymers, even though there has been continuing and growing interest in inorganic liquid crystals. Recent advances in the control of the sizes and shapes of inorganic nanocrystals allow for the formation of a broad class of new inorganic liquid crystals. Here we show the formation of liquid crystalline phases of CdSe semiconductor nanorods. These new liquid crystalline phases may have great importance for both application and fundamental study.

  4. Electrochemical sensing of nuclear matrix protein 22 in urine with molecularly imprinted poly(ethylene-co-vinyl alcohol) coated zinc oxide nanorod arrays for clinical studies of bladder cancer diagnosis.

    PubMed

    Lee, Mei-Hwa; Thomas, James L; Chang, Yu-Chia; Tsai, Yuh-Shyan; Liu, Bin-Da; Lin, Hung-Yin

    2016-05-15

    In 1996 and 2000, the US Food and Drug Administration (FDA) approved the use of Nuclear matrix protein 22 (NMP22) as a monitoring tool for predicting the recurrence/clearing of bladder cancer, and for screening undiagnosed individuals who have symptoms of, or are at risk for, that disease. The fabrication of electrodes for sensing NMP22 and their integration with a portable potentiostat in a homecare system may have great value. This work describes a sensing element comprised of molecularly imprinted polymers (MIPs) for the specific recognition of NMP22 target molecules. Zinc oxide (ZnO) nanorods (214 ± 45 nm in diameter and 1.08 ± 0.11 μm long) were hydrothermally grown on the sensing electrodes to increase the surface area to be coated with MIPs. A portable potentiostat was assembled and a data acquisition (DAQ) card and the Labview program were utilized to monitor electrochemical reaction to sense NMP22 in urine samples. Finally, in phase 0 clinical trials, measurements were made of samples from a few patients with bladder cancer using the NMP22 MIP-coated ZnO nanorods electrodes that were integrated into a portable potentiostat, revealing NMP 22 concentrations in the range 128 ± 19 to 588 ± 53 ng/mL. PMID:26774095

  5. Horizontally assembled green InGaN nanorod LEDs: scalable polarized surface emitting LEDs using electric-field assisted assembly

    PubMed Central

    Park, Hoo Keun; Yoon, Seong Woong; Eo, Yun Jae; Chung, Won Woo; Yoo, Gang Yeol; Oh, Ji Hye; Lee, Keyong Nam; Kim, Woong; Do, Young Rag

    2016-01-01

    In this study, we report the concerted fabrication process, which is easy to transform the size of active emitting area and produce polarized surface light, using the electric-field-assisted assembly for horizontally assembled many tiny nanorod LEDs between two metal electrodes. We fabricate the millions of individually separated 1D nanorod LEDs from 2D nanorod arrays using nanosphere lithography, etching and cutting process of InGaN/GaN LED structure on a flat sapphire substrate. The horizontally assembled InGaN-based nanorods LED device shows bright (~2,130 cd/m2) and uniform polarized (polarization ratio, ρ = ~0.61) green emissions from large area (0.7 cm × 0.6 cm) planar surface. The realization of a horizontally assembled nanorod LED device can prove the concept of an innovative idea to fabricate formable and scalable polarized surface LED lighting. PMID:27324568

  6. Horizontally assembled green InGaN nanorod LEDs: scalable polarized surface emitting LEDs using electric-field assisted assembly

    NASA Astrophysics Data System (ADS)

    Park, Hoo Keun; Yoon, Seong Woong; Eo, Yun Jae; Chung, Won Woo; Yoo, Gang Yeol; Oh, Ji Hye; Lee, Keyong Nam; Kim, Woong; Do, Young Rag

    2016-06-01

    In this study, we report the concerted fabrication process, which is easy to transform the size of active emitting area and produce polarized surface light, using the electric-field-assisted assembly for horizontally assembled many tiny nanorod LEDs between two metal electrodes. We fabricate the millions of individually separated 1D nanorod LEDs from 2D nanorod arrays using nanosphere lithography, etching and cutting process of InGaN/GaN LED structure on a flat sapphire substrate. The horizontally assembled InGaN-based nanorods LED device shows bright (~2,130 cd/m2) and uniform polarized (polarization ratio, ρ = ~0.61) green emissions from large area (0.7 cm × 0.6 cm) planar surface. The realization of a horizontally assembled nanorod LED device can prove the concept of an innovative idea to fabricate formable and scalable polarized surface LED lighting.

  7. Horizontally assembled green InGaN nanorod LEDs: scalable polarized surface emitting LEDs using electric-field assisted assembly.

    PubMed

    Park, Hoo Keun; Yoon, Seong Woong; Eo, Yun Jae; Chung, Won Woo; Yoo, Gang Yeol; Oh, Ji Hye; Lee, Keyong Nam; Kim, Woong; Do, Young Rag

    2016-01-01

    In this study, we report the concerted fabrication process, which is easy to transform the size of active emitting area and produce polarized surface light, using the electric-field-assisted assembly for horizontally assembled many tiny nanorod LEDs between two metal electrodes. We fabricate the millions of individually separated 1D nanorod LEDs from 2D nanorod arrays using nanosphere lithography, etching and cutting process of InGaN/GaN LED structure on a flat sapphire substrate. The horizontally assembled InGaN-based nanorods LED device shows bright (~2,130 cd/m(2)) and uniform polarized (polarization ratio, ρ = ~0.61) green emissions from large area (0.7 cm × 0.6 cm) planar surface. The realization of a horizontally assembled nanorod LED device can prove the concept of an innovative idea to fabricate formable and scalable polarized surface LED lighting. PMID:27324568

  8. Synthesis and characterization of Cu-doped ZnO nanorods chemically grown on flexible substrate

    NASA Astrophysics Data System (ADS)

    Shabannia, R.

    2016-08-01

    Vertically aligned undoped and Cu-doped ZnO nanorods array were successfully grown on flexible substrate by chemical bath deposition method at a low 0074emperature. The fabricated materials were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and photoluminescence (PL) spectroscopy. XRD analysis showed that Cu doping improves the crystallinity of the fabricated ZnO nanorods. The mean diameter and bending of the ZnO nanorods increase with an increase of Cu doping, but the density of Cu-doped ZnO nanorods almost unchanged. Room temperature PL measurement displayed increased intensity in UV peak and decreased visible peak after Cu doping.

  9. Zinc oxide nanorod growth on gold islands prepared by microsphere lithography on silicon and quartz.

    PubMed

    Blackledge, Charles W; Szarko, Jodi M; Dupont, Aurélie; Chan, George H; Read, Elizabeth L; Leone, Stephen R

    2007-09-01

    Gold islands, vapor deposited on silicon and quartz by microsphere lithography patterning, are used to nucleate arrays of ZnO nanorods. ZnO is grown on approximately 0.32 microm2 Au islands by carbothermal reduction in a tube furnace. Scanning electron microscopy (SEM) and energy dispersive atomic X-ray spectroscopy (EDS) confirm that the gold effectively controls the sites of nucleation of ZnO. Atomic force microscopy (AFM) shows that approximately 30 nm diameter nanorods grow horizontally, along the surface. Alloy droplets that are characteristic of the vapor-liquid-solid (VLS) mechanism are observed at the tips of the nanorods. The spatial growth direction of VLS catalyzed ZnO nanorods is along the substrate when they nucleate from gold islands on silicon and quartz. The energy of adhesion of the VLS droplet to the surface can account for the horizontal growth. PMID:18019171

  10. Effect of Zinc Nitrate Concentration on the Optical and Morphological Properties of ZnO Nanorods for Photovoltaic Applications.

    PubMed

    Kim, Sung Jae; Anwar, M S; Heo, Si-Nae; Koo, Bon Heun

    2016-06-01

    We report the effect of zinc nitrate (ZN) concentration on the growth of zinc oxide (ZnO) nanorods and their optical and morphological properties. As prepared ZnO nanorods on glass substrate were characterized using field emission scanning electron microscopy (FE-SEM), ultra violet-visible (UV-Vis), Raman and Photo-luminescence (PL) spectroscopy. FE-SEM results show that the nanorods were obtained for the 0.033 and 0.053 M concentration of ZN. As the ZN concentration increased from 0.033 M to 0.053 M, the diameter of the nanorods was increased. It indicated that the diameter of the nanorods was affected by the ZN concentration. The Raman spectra of nanorods show only one peak at 438 cm(-1) corresponding to E2(high) high mode, which means that ZnO nanorods grown perpendicularly on the glass substrate, i.e., the ZnO nanorod arrays are highly c-axis oriented. Room-temperature PL spectrum of the as-grown ZnO nanorods reveals a near-band-edge (NBE) emission peak and defect induced green light emission. The green light emission band at -579 nm might be attributed to surface oxygen vacancies or defects. The UV-visible measurements reflect that the total transmittance for the as grown ZnO nanorods is over 80%. The simple technique presented in this study to grow ZnO nanorods on a glass substrate can be helpful for making the cost effective photovoltaic devices. PMID:27427680

  11. Tailored to Fit

    ERIC Educational Resources Information Center

    Milbradt, Allan; Klock, Ed

    2006-01-01

    Building a new school can be exciting and creative. The process enables parents, students, educators and the community to explore their dreams and priorities, and create a facility tailored to their unique needs. Unfortunately, the process also can leave education institutions and communities feeling like they've bought an "off-the-rack" facility…

  12. Elastically tailored composite structures

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Elastically tailored composite structures using out-of-autoclave processes. Several unsymetric autoclave-cured and electron-beam-cured composite laminates are compared. Cantilevered beam (unbalanced/asymetric laminate) used to demonstrate bend-twist coupling effects. Photographed in building 1145, photographic studio.

  13. Growth of Cu2ZnSnS4 Nanocrystallites on TiO2 Nanorod Arrays as Novel Extremely Thin Absorber Solar Cell Structure via the Successive-Ion-Layer-Adsorption-Reaction Method.

    PubMed

    Wang, Zhuoran; Demopoulos, George P

    2015-10-21

    Cu2ZnSnS4 (CZTS) is an environmentally benign semiconductor with excellent optoelectronic properties that attracts a lot of interest in thin film photovoltaics. In departure from that conventional configuration, we fabricate and test a novel absorber-conductor structure featuring in situ successive-ion-layer-adsorption-reaction (SILAR)-deposited CZTS nanocrystallites as a light absorber on one-dimensional TiO2 (rutile) nanorods as an electron conductor. The effectiveness of the nanoscale heterostructure in visible light harvesting and photoelectron generation is demonstrated with an initial short circuit current density of 3.22 mA/cm(2) and an internal quantum efficiency of ∼60% at the blue light region, revealing great potential in developing CZTS extremely thin absorber (ETA) solar cells. PMID:26422062

  14. TAILOR: A FORTRAN Procedure for Interactive Tailored Testing

    ERIC Educational Resources Information Center

    Cudeck, Robert A.; And Others

    1977-01-01

    TAILOR, a FORTRAN computer program for tailored testing, is described. The procedure for a joint ordering of persons and items with no pretesting as the basis for the tailored test is given, and a brief discussion of the computer program is included. (Author/JKS)

  15. Sputtering nickel-molybdenum nanorods as an excellent hydrogen evolution reaction catalyst

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Xiong, Kun; Nie, Yao; Wang, Xiaoxue; Liao, Jianhua; Wei, Zidong

    2015-11-01

    We report a novel fabrication of nickel-molybdenum alloy nanorods catalyst for hydrogen evolution reaction (HER), which is prepared by co-deposition of pure nickel and molybdenum in a multisource sputtering system on the surface of Ni foam substrate. The Ni-Mo alloy film exhibits favorable vertical nanorods structure and presents the most efficient activity for HER compared to the film only including one metal element. The remarkably enhanced catalytic activity is attributed to its ordered array geometry as well as the synergistic interaction between Ni and Mo. Meanwhile, the open space within nanorod arrays facilitates the electrolyte penetration and diffusion of ionic species, allowing high utilization efficiency of active species as well as rapidly release of evolved hydrogen gas from the electrode surface.

  16. Spectral tailoring device

    DOEpatents

    Brager, H.R.; Schenter, R.E.; Carter, L.L.; Karnesky, R.A.

    1987-08-05

    A spectral tailoring device for altering the neutron energy spectra and flux of neutrons in a fast reactor thereby selectively to enhance or inhibit the transmutation rate of a target metrical to form a product isotope. Neutron moderators, neutron filters, neutron absorbers and neutron reflectors may be used as spectral tailoring devices. Depending on the intended use for the device, a member from each of these four classes of materials could be used singularly, or in combination, to provide a preferred neutron energy spectra and flux of the neutrons in the region of the target material. In one embodiment of the invention, an assembly is provided for enhancing the production of isotopes, such as cobalt 60 and gadolinium 153. In another embodiment of the invention, a spectral tailoring device is disposed adjacent a target material which comprises long lived or volatile fission products and the device is used to shift the neutron energy spectra and flux of neutrons in the region of the fission products to preferentially transmute them to produce a less volatile fission product inventory. 6 figs.

  17. Reactive Oxygen Species Driven Angiogenesis by Inorganic Nanorods

    PubMed Central

    Patra, Chitta Ranjan; Kim, Jong Ho; Pramanik, Kallal; d’Uscio, Livius V.; Patra, Sujata; Pal, Krishnendu; Ramchandran, Ramani; Strano, Michael S; Mukhopadhyay, Debabrata

    2011-01-01

    The exact mechanism of angiogenesis by europium hydroxide nanorods was unclear. In this study we have showed that formation of reactive oxygen species (H2O2 and O2•−) are involved in redox signaling pathways during angiogenesis, important for cardiovascular and ischemic diseases. Here we used single-walled carbon nanotube (SWNT) sensor array to measure the single-molecule efflux of H2O2 and a HPLC method for the determination of O2•− from endothelial cells in response to pro-angiogenic factors. Additionally, ROS-mediated angiogenesis using inorganic nanorods was observed in transgenic (fli1a:EGFP) zebrafish embryos. PMID:21967244

  18. Bulk plasmon-polaritons in hyperbolic nanorod metamaterial waveguides

    PubMed Central

    Vasilantonakis, Nikolaos; Nasir, Mazhar E; Dickson, Wayne; Wurtz, Gregory A; Zayats, Anatoly V

    2015-01-01

    Hyperbolic metamaterials comprised of an array of plasmonic nanorods provide a unique platform for designing optical sensors and integrating nonlinear and active nanophotonic functionalities. In this work, the waveguiding properties and mode structure of planar anisotropic metamaterial waveguides are characterized experimentally and theoretically. While ordinary modes are the typical guided modes of the highly anisotropic waveguides, extraordinary modes, below the effective plasma frequency, exist in a hyperbolic metamaterial slab in the form of bulk plasmon-polaritons, in analogy to planar-cavity exciton-polaritons in semiconductors. They may have very low or negative group velocity with high effective refractive indices (up to 10) and have an unusual cut-off from the high-frequency side, providing deep-subwavelength (λ0/6–λ0/8 waveguide thickness) single-mode guiding. These properties, dictated by the hyperbolic anisotropy of the metamaterial, may be tuned by altering the geometrical parameters of the nanorod composite. PMID:26693254

  19. Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods

    NASA Astrophysics Data System (ADS)

    Watson, Derek W.; Jenkins, Stewart D.; Ruostekoski, Janne; Fedotov, Vassili A.; Zheludev, Nikolay I.

    2016-03-01

    We show how the elusive toroidal dipole moment appears as a radiative excitation eigenmode in a metamolecule resonator that is formed by pairs of plasmonic nanorods. We analyze one such nanorod configuration—a toroidal metamolecule. We find that the radiative interactions in the toroidal metamolecule can be qualitatively represented by a theoretical model based on an electric point dipole arrangement. Both a finite-size rod model and the point dipole approximation demonstrate how the toroidal dipole moment is subradiant and difficult to excite by incident light. By means of breaking the geometric symmetry of the metamolecule, the toroidal mode can be excited by linearly polarized light and appears as a Fano resonance dip in the forward scattered light. We provide simple optimization protocols for maximizing the toroidal dipole mode excitation. This opens up possibilities for simplified control and driving of metamaterial arrays consisting of toroidal dipole unit-cell resonators.

  20. Nanoheteroepitaxy of GaN on AlN/Si(111) nanorods fabricated by nanosphere lithography

    NASA Astrophysics Data System (ADS)

    Lee, Donghyun; Shin, In-Su; Jin, Lu; Kim, Donghyun; Park, Yongjo; Yoon, Euijoon

    2016-06-01

    Nanoheteroepitaxy (NHE) of GaN on an AlN/Si(111) nanorod structure was investigated by metal-organic chemical vapor deposition. Silica nanosphere lithography was employed to fabricate a periodic hexagonal nanorod array with a narrow gap of 30 nm between the nanorods. We were successful in obtaining a fully coalesced GaN film on the AlN/Si(111) nanorod structure. Transmission electron microscopy revealed that threading dislocation (TD) bending and termination by stacking faults occurred near the interface between GaN and the AlN/Si(111) nanorods, resulting in the reduction of TD density for the NHE GaN layer. The full width at half-maximum of the X-ray rocking curve for (102) plane of the NHE GaN was found to decrease down to 728 arcsec from 1005 arcsec for the GaN layer on a planar AlN/Si(111) substrate, indicating that the crystalline quality of the NHE GaN was improved. Also, micro-Raman measurement showed that tensile stress in the NHE GaN layer was reduced significantly as much as 70% by introducing air voids between the nanorods.

  1. Optoelectrical and magnetic characteristics of Mn doped Zn1-xSnxO nanorods

    NASA Astrophysics Data System (ADS)

    Hsu, Tsung-Yin; Lai, Shang-Hung; Hsieh, Hui-Huang; Lan, Ming-Der; Su, Chih-Chuan; Ho, Mon-Shu

    2013-01-01

    This paper describes a new method of fabricating Mn doped Zn1-xSnxO nanorod arrays on a silicon (111) substrate. The proposed method is a gold catalytic vapor-liquid-solid mechanism in a multi-layer deposition process using nanosphere lithographic patterning. Each step of the growth process was monitored using atomic force microscopy to ensure uniformity in the patterns and nanorods. The crystal structure and characteristics of the Mn doped Zn1-xSnxO nanaorods were determined using the X-ray diffraction analysis, scanning electron microscopy, high resolution transmission electron microscopy, and electron diffraction patterns corresponding to the selected area. The lattice constant along the Z-axis was calculated from the indexed pattern, as approximately 5.1 Å. This differs slightly from what was expected for undoped ZnO nanorods. Energy dispersive X-ray spectrometry provided information related to the chemistry of the ZnO nanorods and electro-optical properties at 363 nm were determined from photoluminescence emissions. Using conductive AFM, the band gap for single doped-ZnO nanorods was determined to be 3-3.45 eV. The magnetic properties were characterized by the measurement of a hysteresis loop. This investigation demonstrates the outstanding potential of patterned Mn doped Zn1-xSnxO nanorods for applications requiring dilute magnetic semiconductors in the future.

  2. Fabrication of ZnO nanorods and assessment of changes in optical and gas sensing properties by increasing their lengths

    NASA Astrophysics Data System (ADS)

    Mehrabian, Masood; Mirabbaszadeh, Kavoos; Afarideh, Hossein

    2013-12-01

    We report a low-temperature process to synthesize highly oriented arrays of ZnO nanorods, based on the epitaxial growth of the ZnO seed layer at a low temperature of 70 °C. The ZnO seed layer was deposited by sol-gel process under mild conditions on the glass substrates. The morphologies and crystal structures of the film and nanorods were characterized by x-ray diffraction and scanning electron microscopy, respectively. ZnO nanorods were grown on ZnO seed layers by hydrothermal method. The effect of growth period on the morphology and optical characteristics (e.g. optical transmission and band-gap energy), hydrophilicity and gas sensing properties of the grown ZnO seed layer (film) and nanorods were investigated. The long nanorods on the seed layer were observed. The increase in the length of the nanorods resulted in a significant reduction in the optical band-gap energy of the nanorods, which was attributed to the formation of further defects in the nanorods during their fast growth. The surface of the ZnO nanorods grown for 6 h was relatively hydrophilic (with a water contact angle of 18°). The fabricated sensors were used to gauge different concentrations of ethanol vapor in the air at different temperatures and evaluated the surface resistance of the sensors as a function of operating temperature and ethanol concentrations. The results showed that the sensitivity of the nanorods changed from 1.3 to 6 (at 300 °C) by increasing the growth period.

  3. 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

  4. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    NASA Astrophysics Data System (ADS)

    Kuang, Y.; van Lare, M. C.; Veldhuizen, L. W.; Polman, A.; Rath, J. K.; Schropp, R. E. I.

    2015-11-01

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  5. VLS-like growth and characterizations of dense ZnO nanorods grown by e-beam process

    NASA Astrophysics Data System (ADS)

    Agarwal, D. C.; Chauhan, R. S.; Avasthi, D. K.; Sulania, I.; Kabiraj, D.; Thakur, P.; Chae, K. H.; Chawla, Amit; Chandra, R.; Ogale, S. B.; Pellegrini, G.; Mazzoldi, P.

    2009-02-01

    We present a new approach to produce ZnO nanorods in a reproducible manner at a temperature lower than other physical vapour deposition techniques, such as the vapour-liquid-solid mechanism. Arrays of well-aligned ZnO nanorods of uniform diameter have been synthesized on the Si substrate precoated with Au, using a simple electron beam evaporation method without the flow of any carrier gas. Scanning electron microscopy and atomic force microscopy characterizations show that as-grown nanorods are well aligned and uniform in diameter. X-ray diffraction measurements and clear lattice fringes in high-resolution transmission electron microscopy image show the growth of good quality polycrystalline hexagonal ZnO nanorods and a lang0 0 2rang growth direction. The polarization-dependent studies of near edge x-ray absorption fine structure (NEXAFS) are performed to investigate the electronic structure of the zinc and oxygen ions. The analysis of NEXAFS spectra at different angles of incidence of photon flux indicates the formation of ZnO nanorods having anisotropic behaviour of O and Zn states. The photoluminescence spectrum exhibits strong ultraviolet emission at 385 nm and the UV-visible spectrum also shows a band-gap transition around 390 nm indicating the good quality of nanorods. The catalytic growth mechanism of the ZnO nanorods is discussed on the basis of experimental results in this work.

  6. Multiple targeting in photoacoustic imaging using bioconjugated gold nanorods

    NASA Astrophysics Data System (ADS)

    Li, Pai-Chi; Wei, Chen-Wei; Liao, Chao-Kang; Chen, Cheng-Dah; Pao, Kuei-Chen; Wang, Churng-Ren Chris; Wu, Ya-Na; Shieh, Dar-Bin

    2006-02-01

    Cancer cells presented altered surface molecules to encourage their growth and metastasis. Expression of oncogeneic surface molecules also play important roles in the prediction of clinical outcome and treatment response of anti-cancer drugs. It is thus conceivable that imaging of cancer lesions while simultaneously obtaining their pathogenic information at molecular level of as many oncogenic proteins as possible is of great clinical significance. Gold nanoparticles have been used as a contrast agent for photoacoustic imaging. In addition, gold nanoparticles can be bioconjugated to probe certain molecular processes. An intriguing property of gold nanoparticles is its ability to tailor its optical properties. For example, size effects on the surface plasmon absorption of spherical gold nanoparticles have shown that the peak optical absorption red-shifts with the increasing particle size. In addition, the optical absorption spectrum of cylindrical gold nanoparticles (i.e., gold nanorods) exhibits a strong absorption band that is directly related to the aspect ratio. With these unique characteristics, selective targeting can be achieved in photoacoustic molecular imaging. Specifically, gold nanorods with different aspect ratios can be bioconjugated to different antibodies. Multiple targeting and simultaneous detection can then be achieved by using laser irradiation at the respective peak optical absorption wavelength. In this study, photoacoustic multiple targeting using gold nanorods is experimentally demonstrated. We have chosen Her2 and CXCR4 as our primary target molecule as Her2 expression is associated with growth characteristics and sensitivity to Herceptin chemotherapy. On the other hand, CXCR4 expression predict the organ-specific metastatic potential of the cancer cells for clinical intervention in advance. Monoclonal antibody (mAb) against Her2/neu was conjugated to nanorods with several different aspect ratios. The agarose gel is suitable for

  7. High performance electrical, magnetic, electromagnetic and electrooptical devices enabled by three dimensionally ordered nanodots and nanorods

    DOEpatents

    Goyal, Amit , Kang; Sukill

    2012-02-21

    Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

  8. High performance superconducting devices enabled by three dimensionally ordered nanodots and/or nanorods

    DOEpatents

    Goyal, Amit

    2013-09-17

    Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

  9. High performance devices enabled by epitaxial, preferentially oriented, nanodots and/or nanorods

    DOEpatents

    Goyal, Amit

    2011-10-11

    Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic, superconducting and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

  10. Zinc oxide nanowires and nanorods fabricated by vapour-phase transport at low temperature

    NASA Astrophysics Data System (ADS)

    Xu, C. X.; Sun, X. W.; Dong, Z. L.; Yu, M. B.; My, T. D.; Zhang, X. H.; Chua, S. J.; White, T. J.

    2004-07-01

    Using zinc chloride as source material, zinc oxide nanowires and nanorods were fabricated by a vapour-phase transport method at low temperature. The nanowires grown on gold-coated silicon showed a uniform diameter of about 40 nm, and the nanorods on copper-coated silicon grew upwards to form flower-like arrays. The x-ray diffraction and transmission electron microscopy analyses demonstrated that the nanostructural zinc oxide grew along the [0001] direction. The growth process was attributed to a vapour-liquid-solid mechanism. Distinct photoluminescent behaviours were observed for zinc oxide nanostructures grown on gold-coated and copper-coated silicon wafers.

  11. Selective photochemical synthesis of Ag nanoparticles on position-controlled ZnO nanorods for the enhancement of yellow-green light emission

    NASA Astrophysics Data System (ADS)

    Park, Hyeong-Ho; Zhang, Xin; Lee, Keun Woo; Sohn, Ahrum; Kim, Dong-Wook; Kim, Joondong; Song, Jin-Won; Choi, Young Su; Lee, Hee Kwan; Jung, Sang Hyun; Lee, In-Geun; Cho, Young-Dae; Shin, Hyun-Beom; Sung, Ho Kun; Park, Kyung Ho; Kang, Ho Kwan; Park, Won-Kyu; Park, Hyung-Ho

    2015-12-01

    A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to preferentially form Ag NPs on ZnO nanorods. The ratio of visible emission to ultraviolet (UV) emission for the Ag NP-decorated ZnO nanorod arrays, synthesized for 30 min, is 20.5 times that for the ZnO nanorod arrays without Ag NPs. The enhancement of the visible emission is believed to associate with the surface plasmon (SP) effect of Ag NPs. The Ag NP-decorated ZnO nanorod arrays show significant SP-induced enhancement of yellow-green light emission, which could be useful in optoelectronic applications. The technique developed here requires low processing temperatures (120 °C and lower) and no high-vacuum deposition tools, suitable for applications such as flexible electronics.A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to

  12. Size dependence of gold nanorod stability: the need for customized surface chemistry

    NASA Astrophysics Data System (ADS)

    SoRelle, Elliott; Liba, Orly; Hussain, Zeshan; Gambhir, Milan; de la Zerda, Adam

    2015-03-01

    Nanoparticles can be synthesized in a wide array of shapes and sizes to suit specific biomedical applications in therapy and imaging. Prerequisite to such applications are particle stability in biological environments, non-toxicity, and facile conjugation of the particle surface with targeting biological moieties (such as antibodies). Here we report significant flaws in the common methods used to functionalize the surface of gold nanorods (GNRs) of larger-than-usual sizes. We find that while GNRs of sizes smaller than 50 x 15 nm can be effectively stabilized by polyethylene glycol (PEG)-based methods, larger GNRs form major aggregates and crash under similar functionalization conditions. Large GNRs may provide enhanced imaging sensitivity in biological applications due to greater optical extinction cross sections, provided that the GNRs can be made biostable. In this study, GNRs of sizes up to 90 x 30 nm were synthesized using two different published methods. Particle morphology and size distributions were characterized using Transmission Electron Microscopy (TEM), and optical spectra were measured by Vis-NIR Spectrometry. The colloidal stability of different-sized GNRs was assayed at various stages of functionalization using zeta potential and Vis-NIR measurements. The results of these experiments indicate that large GNRs functionalized with PEG undergo irreversible aggregation after minimal washing. We find that coating large GNRs with polystyrene sulfonate (PSS) instead of PEG vastly improves GNR stability in water and serum. Moreover, we provide a novel platform for conjugating biomolecules of interest to PSS-coated large GNRs. We show that larger GNRs produce stronger photoacoustic signal than commonly used smaller GNRs, indicating an advantage of using large GNRs for biomedical imaging. Our observations underscore that the biomedical advantages of novel nanoparticle synthesis methods may not be realized without tailored surface functionalization methods. More

  13. An efficient methodology for measurement of the average electrical properties of single one-dimensional NiO nanorods

    NASA Astrophysics Data System (ADS)

    Patil, Ranjit A.; Devan, Rupesh S.; Lin, Jin-Han; Liou, Yung; Ma, Yuan-Ron

    2013-10-01

    We utilized a metal tantalum (Ta) ball-probe to measure the electrical properties of vertical-aligned one-dimensional (1D) nickel-oxide (NiO) nanorods. The 1D NiO nanorods (on average, ~105 nm wide and ~700 nm long) are synthesized using the hot-filament metal-oxide vapor deposition (HFMOVD) technique, and they are cubic phased and have a wide bandgap of 3.68 eV. When the 1D NiO nanorods are arranged in a large-area array in ohmic-contact with the Ta ball-probe, they acted as many parallel resistors. By means of a rigorous calculation, we can easily acquire the average resistance RNR and resistivity ρNR of a single NiO nanorod, which were approximately 3.1 × 1013 Ω and 4.9 × 107 Ω.cm, respectively.

  14. Piezoelectric ZnO-nanorod-structured pressure sensors using GaN-based field-effect-transistor

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Ting; Chiu, Ying-Shuo

    2015-02-01

    To utilize the piezoelectric property of ZnO nanorods, the ZnO nanorod array was grown on the AlGaN/GaN field-effect-transistor as the pressure sensors. The drain-source current of the ZnO nanorod-structured-AlGaN/GaN FET pressure sensors can be effectively modulated by the induced gate voltage caused from the piezoelectric phenomenon of ZnO nanorods under different pressures. The pressure sensors revealed the linearly response current under the pressure from 19.6 mN/mm2 to 490 mN/mm2. The ratio of the response current achieved 2.67% under the pressure of 490 mN/mm2. The induced piezoelectric potential under different pressure was also calculated and obtained in this work.

  15. Tailored Taylor vortices

    NASA Astrophysics Data System (ADS)

    Sprague, M. A.; Weidman, P. D.; Macumber, S.; Fischer, P. F.

    2008-01-01

    The stability of circular Couette flow in discontinuous axisymmetric geometries is investigated using numerical simulations and physical experiments. By contouring the geometry of the inner cylinder, Taylor vortices can be made to appear in discrete sections along the length of the cylinder while adjoining sections remain stable. The disparate flows are connected by transition regions that arise from the stability of the axially nonuniform base flow state. The geometry of the inner cylinder can be tailored to produce the simultaneous onset of Taylor vortices of different wavelength in neighboring sections. In another variant, a stack of inner cylinders of common radius are made to rotate independently to produce adjacent regions of stable and unstable flow.

  16. Tailoring Biointerfaces for Electrocatalysis.

    PubMed

    Milton, Ross D; Wang, Tao; Knoche, Krysti L; Minteer, Shelley D

    2016-03-15

    Bioelectrocatalysis is an expanding research area due to the use of this type of electrocatalysis in electrochemical biosensors, biofuel cells, bioelectrochemical cells, and biosolar cells. This feature article discusses recent advancements in tailoring the biointerface between electrodes and biocatalysts for facile electrocatalysis. This includes the design of pyrene moieties for directing the orientation of biocatalysts on electrode surfaces and mediation as well as the rational design of redox polymers for self-exchange-based electron transport to/from biocatalysts and the electrode and the use of bioscaffolding techniques for designing the bioelectrode structure. However, recent advances in the past decade have shown the importance of hybrid bioelectrocatalytic systems, and future work will be needed to use these same pyrene, redox polymer, and bioscaffolding techniques for hybrid bioelectrocatalysis. PMID:26898265

  17. Spatiotemporal Temperature Distribution and Cancer Cell Death in Response to Extracellular Hyperthermia Induced by Gold Nanorods

    PubMed Central

    Huang, Huang-Chiao; Rege, Kaushal; Heys, Jeffrey J.

    2010-01-01

    Plasmonic nanoparticles have shown promise in hyperthermic cancer therapy, both in vitro and in vivo. Previous reports have described hyperthermic ablation using targeted and non-targeted nanoparticles internalized by cancer cells, but most reports do not describe a theoretical analysis for determining optimal parameters. The focus of the current research was first to evaluate the spatiotemporal temperature distribution and cell death induced by extracellular hyperthermia in which gold nanorods (GNRs) were maintained in the dispersion outside human prostate cancer cells. The nanorod dispersion was irradiated with near infrared (NIR) laser and the spatiotemporal distribution of temperature was determined experimentally. This information was employed to develop and validate theoretical models of spatiotemporal temperature profiles for gold nanorod dispersions undergoing laser irradiation, and the impact of the resulting heat generation on the viability of human prostate cancer cells. A cell injury/death model was then coupled to the heat transfer model to predict spatial and temporal variations in cell death and injury. The model predictions agreed well with experimental measurements of both, temperature and cell death profiles. Finally, the model was extended to examine the impact of selective binding of gold nanorods to cancer cells compared to non-malignant cells, coupled with a small change in cell injury activation energy. The impact of these relatively minor changes results in a dramatic change in the overall cell death rate. Taken together, extracellular hyperthermia using gold nanorods is a promising strategy and tailoring the cellular binding efficacy of nanorods can result in varying therapeutic efficacies using this approach. PMID:20387828

  18. One-step growth of 3D CoNi2S4 nanorods and cross-linked NiCo2S4 nanosheet arrays on carbon paper as anodes for high-performance lithium ion batteries.

    PubMed

    Yang, Weiwei; Chen, Liang; Yang, Jie; Zhang, Xiang; Fang, Chun; Chen, Zhiling; Huang, Lin; Liu, Jianguo; Zhou, Yong; Zou, Zhigang

    2016-04-01

    3D CoNi2S4 and cross-linked NiCo2S4 arrays have been grown on carbon paper (CP) using a one-step hydrothermal method. The 3D cross-linked structure provides a convenient channel for electron and lithium-ion (Li(+)) transport and performs a facile strain relaxation during cycling, exhibits high capacity, excellent rate capability and superior cycle performance. PMID:27001486

  19. Fabrication and characterization of plasmonic nanorods with high aspect ratios

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaoxiao; Hu, Sheng; Li, Zhigang; Lv, Jiangtao; Si, Guangyuan

    2016-08-01

    Metallic nanostructures with high aspect ratios are important for developing devices in photonics and integrated optics. However, fabricating well-aligned plasmonic arrays is challenging due to the difficulties of etching metals. In this work, we investigate the feasibility of constructing high aspect ratio nanorods with desired shapes and controllable geometric parameters using direct focused ion beam etching. The whole fabrication process only involves a metal-deposition step and a single milling of designed patterns. Detailed characterizations of the fabricated devices are also experimentally demonstrated.

  20. Tuning near-field enhancements on an off-resonance nanorod dimer via temporally shaped femtosecond laser

    NASA Astrophysics Data System (ADS)

    Du, Guangqing; Yang, Qing; Chen, Feng; Lu, Yu; Wu, Yanmin; Ou, Yan; Hou, Xun

    2015-11-01

    We theoretically investigated ultrafast thermal dynamics tuning of near-field enhancements on an off-resonance gold nanorod dimer via temporally shaped femtosecond (fs) laser double pulses. The nonequilibrium thermal excitation is self-consistently coupled into a near-field scattering model for exploring the ultrafast near-field enhancement effects. It is revealed that the near electric-field localized within the gold nanorod dimer can be largely promoted via optimizing the temporal separation and the pulse energy ratio of temporally shaped femtosecond laser double pulses. The results are explained as thermal dynamics manipulation of plasmon resonances in the nanorod dimer via tailoring temporally shaped femtosecond laser. This study provides basic understanding for tuning near-field properties on poorly fabricated metallic nano-structures via temporally shaped femtosecond laser, which can find potential applications in the fields such as fs super-resolution near-field imaging, near-field optical tweezers, and fs photothermal therapy.

  1. Nanorod solar cell with an ultrathin a-Si:H absorber layer

    NASA Astrophysics Data System (ADS)

    Kuang, Yinghuan; van der Werf, Karine H. M.; Houweling, Z. Silvester; Schropp, Ruud E. I.

    2011-03-01

    We propose a nanostructured three-dimensional (nano-3D) solar cell design employing an ultrathin hydrogenated amorphous silicon (a-Si:H) n-i-p junction deposited on zinc oxide (ZnO) nanorod arrays. The ZnO nanorods were prepared by aqueous chemical growth at 80 °C. The photovoltaic performance of the nanorod/a-Si:H solar cell with an ultrathin absorber layer of only 25 nm is experimentally demonstrated. An efficiency of 3.6% and a short-circuit current density of 8.3 mA/cm2 were obtained, significantly higher than values achieved for planar or even textured counterparts with three times thicker (˜75 nm) a-Si:H absorber layers.

  2. Physiological investigation of gold nanorods toward watermelon.

    PubMed

    Wan, Yujie; Li, Junli; Ren, Hongxuan; Huang, Jin; Yuan, Hong

    2014-08-01

    The objective of the present study was to evaluate the phytotoxicity and oxidant stress of the gold nanorods toward watermelon, and hence give a quantitative risk assessment of both seeds and plants phase. The seed germination, the activity of antioxidant enzymes, and the contents of soluble protein and malondialdehyde (MDA) have been measured while the plant roots were observed by transmission electron microscopy (TEM). It was found that the gold nanorods significantly promoted the root elongation. Furthermore, the results on the enzymes activities of plant indicated that oxidative stress happened in the plant treated with gold nanorods. However, the gold nanorods resulted in the phytotoxicity toward plant especially at high concentration. The TEM images of the plant roots with and without the treatment of gold nanorods showed the significant different size of starch granules. In conclusion, significant physiological changes of plant occurred after treatment with the gold nanorods. PMID:25936063

  3. Mica sheets with embedded metal nanorods: Chemical imaging in a topographically smooth structure

    SciTech Connect

    Graca, Malgorzata; Turner, Jeff; Marshall, Michael; Granick, Steve

    2007-09-15

    We demonstrate the concept to combine topographical smoothness and plasmonic properties to produce flat substrates with surface enhanced Raman spectroscopy activity--properties that may find use in nanotribology and other thin film applications. Preliminary findings to this end are described. A dual-beam focused ion beam (FIB) system is used to drill large arrays of small pores in single crystals of mica, 2-6 {mu}m thick, yielding controlled cross sections (squares, triangles, and circles), sizes (100 nm to many microns), and arrangements (square, hexagonal, and random). When filled with metals, arrays result to embedded nanorods with their long axis oriented normal to the surface. As an extension of this method, arrays of nanorods standing perpendicular to a supporting surface can also be produced.

  4. Multi-component nanorods for vaccination applications

    NASA Astrophysics Data System (ADS)

    Salem, A. K.; Hung, C. F.; Kim, T. W.; Wu, T. C.; Searson, P. C.; Leong, K. W.

    2005-04-01

    Immune responses from Au/Ni nanorods prepared by electrochemical deposition in alumina templates are evaluated in C57BL/6 mice. When the nanorods are bombarded into skin, they generate a strong CD8 T-cell and antibody response. When pcDNA3 is bound to the Ni segment of the nanorod, it provides a strong immunostimulatory adjuvant effect to the antigen bound on the Au segment.

  5. Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials.

    PubMed

    Song, Haojie; Zhang, Junxi; Fei, Guangtao; Wang, Junfeng; Jiang, Kang; Wang, Pei; Lu, Yonghua; Iorsh, Ivan; Xu, Wei; Jia, Junhui; Zhang, Lide; Kivshar, Yuri S; Zhang, Lin

    2016-10-14

    Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate. PMID:27607837

  6. Impact of the nanorod structure on the tandem thin-film solar cell.

    PubMed

    Tang, M; Chang, S T; Huang, C-X; Liu, Y T; Chen, Y H

    2011-07-01

    The novel thin-film solar cell was investigated with a nanorod structure that could solve the conflict between light absorption and carrier transport in the amorphous silicon (a-Si)/amorphous silicon-germanium (a-SiGe) tandem thin-film solar cell. This structure has an n-type a-Si nanorod array on the substrate, and an a-SiOx p-layer and an a-SiGe i-layer are sequentially grown along the surface of each n-type a-Si nanorod, for the bottom cell. After the above bottom-cell process, a similar process is used to fabricate an amorphous Si p-i-n top cell on the bottom cell. Under sunlight illumination, the light is absorbed along the vertical direction of the nanorod, but as the carrier transport is along the horizontal direction, the nanorod may absorb most of the sunlight. In the meantime, the solar cell is still thin enough for the effective transport of photogenerated carriers. PMID:22121598

  7. Single inorganic-organic hybrid photovoltaic nanorod

    NASA Astrophysics Data System (ADS)

    Yoo, Sang-Hoon; Liu, Lichun; Ku, Tea-Woong; Hong, Soonchang; Whang, Dongmok; Park, Sungho

    2013-09-01

    We demonstrate that single photovoltaic (PV) nanorods can be readily fabricated by electrochemical processing in solution-phase under ambient conditions. A porous Au nanorod electrode in the core of the PV nanorod was central to both its structural formation and superior performance. We examined an intrinsically conducting polymer (polypyrrole) and an inorganic semiconductor (cadmium selenide) as precursor materials. Through an extremely simple and cost-effective fashioning process (solution-phase, room temperature), unadorned PV nanorods with up to 1.1% power conversion efficiency were obtained.

  8. Graded core/shell semiconductor nanorods and nanorod barcodes

    DOEpatents

    Alivisatos, A. Paul; Scher, Erik C.; Manna, Liberato

    2009-05-19

    Disclosed herein is a graded core/shell semiconductor nanorod having at least a first segment of a core of a Group II-VI, Group III-V or a Group IV semiconductor, a graded shell overlying the core, wherein the graded shell comprises at least two monolayers, wherein the at least two monolayers each independently comprise a Group II-VI, Group III-V or a Group IV semiconductor.

  9. Electrochemical fabrication and evaluation of highly sensitive nanorod-modified electrodes for a biotin/avidin system.

    PubMed

    Lee, Seung-Jun; Anandan, Venkataramani; Zhang, Guigen

    2008-02-28

    Bioaffinity sensors need to be rapid, specific, and highly sensitive. To realize these features, electrodes that can elicit high electrochemical performance are necessary. In this study, we developed nanorod array electrode and performed cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments to study the interfacial properties of the nanorod array electrode with Fe(CN)(6)(3-/4-) as the redox molecules. Results showed that both the CV and EIS measurements captured very well the resistive and capacitive changes due to the adsorption of functionalizing molecules and the coupling between avidin and biotin. The EIS measurements were more sensitive in discriminating small changes caused by the surface adsorption of various molecules. The use of avidin-functionalized gold nanorod modified electrodes had led to much increased detection sensitivity along with a detection-limit as low as 1 ng/mL of biotin. PMID:18077147

  10. Au nanorod helical superstructures with designed chirality.

    PubMed

    Lan, Xiang; Lu, Xuxing; Shen, Chenqi; Ke, Yonggang; Ni, Weihai; Wang, Qiangbin

    2015-01-14

    A great challenge for nanotechnology is to controllably organize anisotropic nanomaterials into well-defined three-dimensional superstructures with customized properties. Here we successfully constructed anisotropic Au nanorod (AuNR) helical superstructures (helices) with tailored chirality in a programmable manner. By designing the 'X' pattern of the arrangement of DNA capturing strands (15nt) on both sides of a two-dimensional DNA origami template, AuNRs functionalized with the complementary DNA sequences were positioned on the origami and were assembled into AuNR helices with the origami intercalated between neighboring AuNRs. Left-handed (LH) and right-handed (RH) AuNR helices were conveniently accomplished by solely tuning the mirrored-symmetric 'X' patterns of capturing strands on the origami. The inter-rod distance was precisely defined as 14 nm and inter-rod angle as 45°, thus a full helix contains 9 AuNRs with its length up to about 220 nm. By changing the AuNR/origami molar ratio in the assembly system, the average number of AuNR in the helices was tuned from 2 to 4 and 9. Intense chiroptical activities arose from the longest AuNR helices with a maximum anisotropy factor of ∼0.02, which is highly comparable to the reported macroscopic AuNR assemblies. We expect that our strategy of origami templated assembly of anisotropic chiral superstructures would inspire the bottom-up fabrication of optically active nanostructures and shed light on a variety of applications, such as chiral fluids, chiral signal amplification, and fluorescence combined chiral spectroscopy. PMID:25516475

  11. A self-reporting tetrazole-based linker for the biofunctionalization of gold nanorods.

    PubMed

    Stolzer, Lukas; Vigovskaya, Antonina; Barner-Kowollik, Christopher; Fruk, Ljiljana

    2015-10-01

    A photochemical approach based on nitrile imine-mediated tetrazole-ene cycloaddition is introduced to functionalize gold nanorods with biomolecules. For this purpose, a bifunctional, photoreactive linker containing thioctic acid as the Au anchoring group and a tetrazole moiety for the light-induced reaction with maleimide-capped DNA was prepared. The tetrazole-based reaction on the nanoparticles' surface results in a fluorescent pyrazoline product allowing for the spectroscopic monitoring of the reaction. This first example of nitrile imine-mediated tetrazole-ene cycloaddition (NITEC)-mediated biofunctionalization of Au nanorods paves the way for the attachment of sensitive biomolecules, such as antibodies and other proteins, under mild conditions and expands the toolbox for the tailoring of nanomaterials. PMID:26303592

  12. Large scale solution assembly of quantum dot-gold nanorod architectures with plasmon enhanced fluorescence.

    PubMed

    Nepal, Dhriti; Drummy, Lawrence F; Biswas, Sushmita; Park, Kyoungweon; Vaia, Richard A

    2013-10-22

    Tailoring the efficiency of fluorescent emission via plasmon-exciton coupling requires structure control on a nanometer length scale using a high-yield fabrication route not achievable with current lithographic techniques. These systems can be fabricated using a bottom-up approach if problems of colloidal stability and low yield can be addressed. We report progress on this pathway with the assembly of quantum dots (emitter) on gold nanorods (plasmonic units) with precisely controlled spacing, quantum dot/nanorod ratio, and long-term colloidal stability, which enables the purification and encapsulation of the assembled architecture in a protective silica shell. Overall, such controllability with nanometer precision allows one to synthesize stable, complex architectures at large volume in a rational and controllable manner. The assembled architectures demonstrate photoluminescent enhancement (5×) useful for applications ranging from biological sensing to advanced optical communication. PMID:24004164

  13. Optoelectronic properties of cauliflower like ZnO-ZnO nanorod/p-Si heterostructure

    NASA Astrophysics Data System (ADS)

    Rajabi, M.; Dariani, R. S.; Iraji zad, A.; Zahedi, F.

    2013-02-01

    The cauliflower like ZnO nanostructures are grown on ZnO nanorods using spray pyrolysis method. First, ZnO nanorod arrays are grown on p-type silicon substrate without catalyst by chemical vapor transport and condensation method in a horizontal tube furnace. Afterwards, the cauliflower like ZnO nanostructures is deposited on top of the ZnO nanorod array. The PL spectra of cauliflower like ZnO nanostructures consist of UV emission bands around 387 nm and a visible emission at ˜440 nm. The current-voltage (I-V) measurement under dark and UV illumination condition are performed to study photodetection of the cauliflower like ZnO-ZnO nanorod/p-Si heterostructure. The experimental data of dark I-V curve show that the tunneling-recombination model is the dominant current transport mechanism in our device heterostructure below 2 V. It is observed that UV photons are absorbed in ZnO and device exhibit 0.07 A/W responsivity at 5 V reverse bias which correspond to quantum efficiency of 26%.

  14. Effect of lattice strain on structural and optical properties of ZnO nanorods grown by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Gautam, Khyati; Singh, Inderpreet; Nirwal, Varun Singh; Singh, Joginder; Peta, Koteswara Rao; Bhatnagar, P. K.

    2016-05-01

    In this work, we have synthesized ZnO nanorods over ZnO seeds/ITO/glass substrate by the facile hydrothermal method. ZnO seeds are grown at different temperatures ranging from 150°C to 550°C in steps of 100°C. We have studied the effect of strain on the structural and optical properties of ZnOnanorods. It was observed that the growth temperature of seed layer has an influence over the lattice strain present in the nanorods. The as synthesized nanorods were characterized by scanning electron microscope (SEM), x-ray diffraction (XRD) and photoluminescence (PL). SEM images confirm the formation of dense arrays of vertically aligned nanorods on seeds which are grown at 350°C. In addition to this, XRD patterns reveal that these ZnO nanorods are preferentially oriented along (002) direction. The strain analysis based on the XRD results reveals that the minimum value of strain is obtained at 350°C which is attributed to the improved crystalline quality of the interface of seed layer and nanorods leading to their c-axis alignment and enhancement of ultraviolet emission as observed in the PL spectra.

  15. Angle-resolved reflectance of obliquely aligned silver nanorods.

    PubMed

    Wang, X J; Abell, J L; Zhao, Y-P; Zhang, Z M

    2012-04-01

    Arrays of silver nanorods (AgNRs) formed by oblique-angle deposition (OAD) are strongly anisotropic, with either metallic or dielectric characteristics depending on the polarization of incident light, and may be used to enhance Raman scattering and surface plasmon polaritons. This work investigates the polarization-dependent reflectance of inclined AgNR arrays at the wavelengths of 635 and 977 nm. The specular reflectance at various incidence angles and the bidirectional reflectance distribution function were measured with a laser scatterometer, while the directional-hemispherical reflectance was measured with an integrating sphere. The AgNR layer is modeled as an effectively homogenous, optically uniaxial material using the effective medium theory to elucidate the dielectric or metallic response for differently polarized incidence. The thin-film optics formulation is modified considering optical anisotropy and surface scattering. This study helps gain a better understanding of optical properties of nanostructured materials. PMID:22505070

  16. Hierarchical organization and molecular diffusion in gold nanorod/silica supercrystal nanocomposites

    NASA Astrophysics Data System (ADS)

    Hamon, Cyrille; Sanz-Ortiz, Marta N.; Modin, Evgeny; Hill, Eric H.; Scarabelli, Leonardo; Chuvilin, Andrey; Liz-Marzán, Luis M.

    2016-04-01

    Hierarchical organization of gold nanorods was previously obtained on a substrate, allowing precise control over the morphology of the assemblies and macroscale spatial arrangement. Herein, a thorough description of these gold nanorod assemblies and their orientation within supercrystals is presented together with a sol-gel technique to protect the supercrystals with mesoporous silica films. The internal organization of the nanorods in the supercrystals was characterized by combining focused ion beam ablation and scanning electron microscopy. A mesoporous silica layer is grown both over the supercrystals and between the individual lamellae of gold nanorods inside the structure. This not only prevented the detachment of the supercrystal from the substrate in water, but also allowed small molecule analytes to infiltrate the structure. These nanocomposite substrates show superior Raman enhancement in comparison with gold supercrystals without silica owing to improved accessibility of the plasmonic hot spots to analytes. The patterned supercrystal arrays with enhanced optical and mechanical properties obtained in this work show potential for the practical implementation of nanostructured devices in spatially resolved ultradetection of biomarkers and other analytes.Hierarchical organization of gold nanorods was previously obtained on a substrate, allowing precise control over the morphology of the assemblies and macroscale spatial arrangement. Herein, a thorough description of these gold nanorod assemblies and their orientation within supercrystals is presented together with a sol-gel technique to protect the supercrystals with mesoporous silica films. The internal organization of the nanorods in the supercrystals was characterized by combining focused ion beam ablation and scanning electron microscopy. A mesoporous silica layer is grown both over the supercrystals and between the individual lamellae of gold nanorods inside the structure. This not only prevented the

  17. Gold nanorods grown on microgels leading to hexagonal nanostructures.

    PubMed

    Kumar, V R Rajeev; Samal, A K; Sreeprasad, T S; Pradeep, T

    2007-08-14

    Hexagonal patterns of gold nanorods were made by assembling gold nanorod-coated poly(N-isopropyl acrylamide) microgels. The required population of nanorods on the microgels was achieved by attaching nanoparticle seeds on the latter and growing them to nanorods. The various materials prepared were characterized by UV-vis spectroscopy and transmission electron microscopy. Similar experiments with nanoparticle-coated or prefabricated nanorod-coated microgels did not give such hexagonal patterns. We suggest that the interlocking of nanorods leads to these regular structures. This is the first report of a solution phase method for assembling nanorods into a hexagonal pattern. PMID:17637011

  18. Preparation of ZnO Nanorod/Graphene/ZnO Nanorod Epitaxial Double Heterostructure for Piezoelectrical Nanogenerator by Using Preheating Hydrothermal.

    PubMed

    Shin, Dong-Myeong; Kang, Seok Hee; Kim, Seongsu; Seung, Wanchul; Tsege, Ermias Libnedengel; Kim, Sang-Woo; Kim, Hyung Kook; Hong, Suck Won; Hwang, Yoon-Hwae

    2016-01-01

    Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we describe a one-step fabrication technique to synthesis freestanding ZnO nanorod/graphene/ZnO nanorod double heterostructure. The preparation of the double heterostructure is performed by using thermal chemical vapor deposition (CVD) and preheating hydrothermal technique. In addition, the morphological properties were characterized by using the scanning electron microscopy (SEM). The utility of freestanding double heterostructure is demonstrated by fabricating the piezoelectric nanogenerator. The electrical output is improved up to 200% compared to that of a single heterostructure owing to the coupling effect of the piezoelectricity between the arrays of ZnO nanorods on the top and bottom of graphene. This unique double heterostructure have a tremendous potential for applications of electrical and optoelectrical devices where the high number density and specific surface area of nanorod are needed, such as pressure sensor, immuno-biosensor and dye-sensitized solar cells. PMID:26863044

  19. Structural and Morphology of ZnO Nanorods Synthesized Using ZnO Seeded Growth Hydrothermal Method and Its Properties as UV Sensing

    PubMed Central

    Ridhuan, Nur Syafinaz; Abdul Razak, Khairunisak; Lockman, Zainovia; Abdul Aziz, Azlan

    2012-01-01

    In this study, zinc oxide (ZnO) nanorod arrays were synthesized using a simple hydrothermal reaction on ZnO seeds/n-silicon substrate. Several parameters were studied, including the heat-treatment temperature to produce ZnO seeds, zinc nitrate concentration, pH of hydrothermal reaction solution, and hydrothermal reaction time. The optimum heat-treatment temperature to produce uniform nanosized ZnO seeds was 400°C. The nanorod dimensions depended on the hydrothermal reaction parameters. The optimum hydrothermal reaction parameters to produce blunt tip-like nanorods (770 nm long and 80 nm in top diameter) were 0.1 M zinc nitrate, pH 7, and 4 h of growth duration. Phase analysis studies showed that all ZnO nanorods exhibited a strong (002) peak. Thus, the ZnO nanorods grew in a c-axis preferred orientation. A strong ultraviolet (UV) emission peak was observed for ZnO nanorods grown under optimized parameters with a low, deep-level emission peak, which indicated high optical property and crystallinity of the nanorods. The produced ZnO nanorods were also tested for their UV-sensing properties. All samples responded to UV light but with different sensing characteristics. Such different responses could be attributed to the high surface-to-volume ratio of the nanorods that correlated with the final ZnO nanorods morphology formed at different synthesis parameters. The sample grown using optimum synthesis parameters showed the highest responsivity of 0.024 A/W for UV light at 375 nm under a 3 V bias. PMID:23189199

  20. Surfactant controlled synthesis of crystalline phosphovanadate nanorods

    SciTech Connect

    Asnani, Minakshi; Thomas, Jency; Sen, Prasenjit; Ramanan, Arunachalam . E-mail: aramanan@chemistry.iitd.ac.in

    2007-04-12

    Phosphovanadate nanorods were obtained in a reaction of vanadium (V) oxide as a precursor and a cationic surfactant, dodecylpyridinium chloride, as structure directing template at pH {approx}3 at room temperature. The composition and morphology of the nanorods was established by powder X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), fourier transform infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The obtained nanorods have diameters of 40-60 nm with lengths up to 1 {mu}m. The effect of reaction parameters such as concentration of surfactant and pH of the solution on the growth of nanorods has been investigated. A plausible mechanism involving the coalescence of nanoparticle 'seeds' leading to one-dimensional nanorods is also discussed. The same reaction when performed under hydrothermal condition, keeping other reaction parameters unchanged, resulted in the formation of phosphovanadate nanospheres of diameter 10-15 nm.

  1. Photoelectrochemical performance of CdS nanorods grafted vertically aligned TiO{sub 2} nanorods

    SciTech Connect

    Liu, Ya; Jiang, Jiangang; Xu, Quan; Li, Mingtao; Guo, Liejin

    2013-11-15

    Graphical abstract: - Highlights: • TiO{sub 2} nanorods/CdS nanorods composite samples were successfully achieved. • The photocurrent density increased by 100 percent compared with pure TiO{sub 2}. • Photocurrent density increase mechanism of this photoanode was also forecasted. - Abstract: In this study, TiO{sub 2} nanorods/CdS nanorods composite samples were successfully synthesized by grafting CdS nanorods on vertically aligned TiO{sub 2} nanorods. A two-step hydrothermal method was used to prepare the samples. Some properties of the samples, such as morphological, structural, and optical properties were characterized by energy-dispersive X-ray detection, field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and ultraviolet-visible spectroscopy. Moreover, photoelectrochemical properties were studied via current-voltage and photocurrent spectrum measurements. The results showed that CdS nanorods grafted on top of TiO{sub 2} nanorods like a lawn. The amount grafted as well as the diameter and crystallinity of CdS nanorods increased first and then decreased as the grafting time increased, due to Ostwald ripening. Under the back-side illumination, the composite film with 2 h grafting time exhibited the highest photocurrent density which was almost twice of that of the pure TiO{sub 2} nanorods.

  2. Fabrication and characterization of silicon wire solar cells having ZnO nanorod antireflection coating on Al-doped ZnO seed layer

    PubMed Central

    2012-01-01

    In this study, we have fabricated and characterized the silicon [Si] wire solar cells with conformal ZnO nanorod antireflection coating [ARC] grown on a Al-doped ZnO [AZO] seed layer. Vertically aligned Si wire arrays were fabricated by electrochemical etching and, the p-n junction was prepared by spin-on dopant diffusion method. Hydrothermal growth of the ZnO nanorods was followed by AZO film deposition on high aspect ratio Si microwire arrays by atomic layer deposition [ALD]. The introduction of an ALD-deposited AZO film on Si wire arrays not only helps to create the ZnO nanorod arrays, but also has a strong impact on the reduction of surface recombination. The reflectance spectra show that ZnO nanorods were used as an efficient ARC to enhance light absorption by multiple scattering. Also, from the current-voltage results, we found that the combination of the AZO film and ZnO nanorods on Si wire solar cells leads to an increased power conversion efficiency by more than 27% compared to the cells without it. PMID:22222067

  3. Role of ZnO thin film in the vertically aligned growth of ZnO nanorods by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Son, Nguyen Thanh; Noh, Jin-Seo; Park, Sungho

    2016-08-01

    The effect of ZnO thin film on the growth of ZnO nanorods was investigated. ZnO thin films were sputter-deposited on Si substrate with varying the thickness. ZnO nanorods were grown on the thin film using a chemical bath deposition (CBD) method at 90 °C. The ZnO thin films showed granular structure and vertical roughness on the surface, which facilitated the vertical growth of ZnO nanorods. The average grain size and the surface roughness of ZnO film increased with an increase in film thickness, and this led to the increase in both the average diameter and the average length of vertically grown ZnO nanorods. In particular, it was found that the average diameter of ZnO nanorods was very close to the average grain size of ZnO thin film, confirming the role of ZnO film as a seed layer for the vertical growth of ZnO nanorods. The CBD growth on ZnO seed layers may provide a facile route to engineering vertically aligned ZnO nanorod arrays.

  4. Visible light-driven CdSe nanotube array photocatalyst

    PubMed Central

    2013-01-01

    Large-scale CdSe nanotube arrays on indium tin oxide (ITO) glass have been synthesized using ZnO nanorod template. The strong visible light absorption in CdSe, its excellent photoresponse, and the large surface area associated with the tubular morphology lead to good visible light-driven photocatalytic capability of these nanotube arrays. Compared to freestanding nanoparticles, such one-piece nanotube arrays on ITO make it very convenient for catalyst recycling after their usage PMID:23680487

  5. Visible light-driven CdSe nanotube array photocatalyst

    NASA Astrophysics Data System (ADS)

    Zhu, Haojun; Li, Quan

    2013-05-01

    Large-scale CdSe nanotube arrays on indium tin oxide (ITO) glass have been synthesized using ZnO nanorod template. The strong visible light absorption in CdSe, its excellent photoresponse, and the large surface area associated with the tubular morphology lead to good visible light-driven photocatalytic capability of these nanotube arrays. Compared to freestanding nanoparticles, such one-piece nanotube arrays on ITO make it very convenient for catalyst recycling after their usage

  6. Visible light-driven CdSe nanotube array photocatalyst.

    PubMed

    Zhu, Haojun; Li, Quan

    2013-01-01

    Large-scale CdSe nanotube arrays on indium tin oxide (ITO) glass have been synthesized using ZnO nanorod template. The strong visible light absorption in CdSe, its excellent photoresponse, and the large surface area associated with the tubular morphology lead to good visible light-driven photocatalytic capability of these nanotube arrays. Compared to freestanding nanoparticles, such one-piece nanotube arrays on ITO make it very convenient for catalyst recycling after their usage. PMID:23680487

  7. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    SciTech Connect

    Kuang, Y.; Lare, M. C. van; Polman, A.; Veldhuizen, L. W.; Schropp, R. E. I.; Rath, J. K.

    2015-11-14

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  8. Growth of ZnO-based nanorod heterostructures and their photonic device applications

    NASA Astrophysics Data System (ADS)

    Yoo, Jinkyoung; Picraux, S. Thomas; Yi, Gyu-Chul

    2011-10-01

    This proceeding summarizes the materials preparation of position-controlled ZnO-based nanorod heterostructures and fabrication of vertically-aligned wide band gap semiconductor nanorod light-emitting devices. Especially the fabrication of GaN/InxGa1-xN/GaN/ZnO nanorod heterostructured visible-light-emitter arrays on sapphire and Si substrates, representing important progress in the field of nanoheteroepitaxy and photonic devices in nanoscale, are reported. Particularly, position-controlled vertical nanostructure arrays make those possible to prepare high-quality material systems without stress or strain accumulation and to fabricate high-performance light-emitting devices (LEDs) with a three-dimensional device configuration. Our method based on nanoheteroepitaxy and position-controlled nanodevice integration for fabricating GaN-based micro-LED arrays constitutes a promising strategy for resolving the issues of conventional GaN LEDs and fabricating high-performance LEDs on various substrates for potential optoelectronic integrated circuits and solid-state lighting applications.

  9. Plasmonics of Gold Nanorods. Considerations for Biosensing

    NASA Astrophysics Data System (ADS)

    Liz-Marzán, Luis M.; Pérez-Juste, Jorge; Pastoriza-Santos, Isabel

    In this chapter, we explore the sensitivity of gold nanorods toward changes in the dielectric constant of the surrounding medium. Experimental data for pure and silica-coated nanorods with varying shell thickness are compared to calculations based on the boundary element method (BEM). They indicate that anisotropy and sharp tips make nanoparticles more environmentally sensitive. We also find that sensitivity decreases as silica shell thickness increases, as expected from a dielectric screening effect. Even when coated with thin shells, gold nanorods are found to be excellent candidates for biosensing applications.

  10. The stabilization and targeting of surfactant-synthesized gold nanorods

    NASA Astrophysics Data System (ADS)

    Rostro-Kohanloo, Betty C.; Bickford, Lissett R.; Payne, Courtney M.; Day, Emily S.; Anderson, Lindsey J. E.; Zhong, Meng; Lee, Seunghyun; Mayer, Kathryn M.; Zal, Tomasz; Adam, Liana; Dinney, Colin P. N.; Drezek, Rebekah A.; West, Jennifer L.; Hafner, Jason H.

    2009-10-01

    The strong cetyltrimethylammonium bromide (CTAB) surfactant responsible for the synthesis and stability of gold nanorod solutions complicates their biomedical applications. The critical parameter to maintain nanorod stability is the ratio of CTAB to nanorod concentration. The ratio is approximately 740 000 as determined by chloroform extraction of the CTAB from a nanorod solution. A comparison of nanorod stabilization by thiol-terminal PEG and by anionic polymers reveals that PEGylation results in higher yields and less aggregation upon removal of CTAB. A heterobifunctional PEG yields nanorods with exposed carboxyl groups for covalent conjugation to antibodies with the zero-length carbodiimide linker EDC. This conjugation strategy leads to approximately two functional antibodies per nanorod according to fluorimetry and ELISA assays. The nanorods specifically targeted cells in vitro and were visible with both two-photon and confocal reflectance microscopies. This covalent strategy should be generally applicable to other biomedical applications of gold nanorods as well as other gold nanoparticles synthesized with CTAB.

  11. [Feasibility of tailored patient education].

    PubMed

    Tóth, Tamás; Dinya, Elek

    2013-03-17

    Patient education has an important role in the prevention and therapy. It enables the delivery of necessary information, development of skills and motivations and supporting to cope with the disease. Although many information sources are available, it is still necessary to provide organized patient education. Tailored patient education was proved to be more effective than using general information materials. The proper use of information technology enables the widespread and cost-effective implementation of tailored patient education. The authors analyse the components necessary for development of such a system. PMID:23477894

  12. Hierarchical organization and molecular diffusion in gold nanorod/silica supercrystal nanocomposites.

    PubMed

    Hamon, Cyrille; Sanz-Ortiz, Marta N; Modin, Evgeny; Hill, Eric H; Scarabelli, Leonardo; Chuvilin, Andrey; Liz-Marzán, Luis M

    2016-04-14

    Hierarchical organization of gold nanorods was previously obtained on a substrate, allowing precise control over the morphology of the assemblies and macroscale spatial arrangement. Herein, a thorough description of these gold nanorod assemblies and their orientation within supercrystals is presented together with a sol-gel technique to protect the supercrystals with mesoporous silica films. The internal organization of the nanorods in the supercrystals was characterized by combining focused ion beam ablation and scanning electron microscopy. A mesoporous silica layer is grown both over the supercrystals and between the individual lamellae of gold nanorods inside the structure. This not only prevented the detachment of the supercrystal from the substrate in water, but also allowed small molecule analytes to infiltrate the structure. These nanocomposite substrates show superior Raman enhancement in comparison with gold supercrystals without silica owing to improved accessibility of the plasmonic hot spots to analytes. The patterned supercrystal arrays with enhanced optical and mechanical properties obtained in this work show potential for the practical implementation of nanostructured devices in spatially resolved ultradetection of biomarkers and other analytes. PMID:26961684

  13. Vertically etched silicon nano-rods as a sensitive electron detector

    NASA Astrophysics Data System (ADS)

    Hajmirzaheydarali, M.; Akbari, M.; Soleimani-Amiri, S.; Sadeghipari, M.; Shahsafi, A.; Farahani, A. Akhavan; Mohajerzadeh, S.

    2015-07-01

    We have used vertically etched silicon nano-rods to realize electron detectors suitable for scanning electron microscopes. The results of deep etching of silicon nano-structures are presented to achieve highly ordered arrays of nano-rods. The response of the electron detector to energy of the primary electron beam and the effects of various sizes and materials has been investigated, indicating its high sensitivity to secondary and back-scattered electrons. The miniaturized structure of this electron detector allows it to be placed in the vicinity of the specimen to improve the resolution and contrast. This detector collects electrons and converts the electron current to voltage directly by means of n-doped silicon nano-rods on a p-type silicon substrate. Silicon nano-rods enhance the surface-to-volume ratio of the detector as well as improving the yield of electron detection. The use of nano-structures and silicon nanowires as an electron detector has led to higher sensitivities than with micro-structures.

  14. Gold coated ZnO nanorod biosensor for glucose detection

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Anuradha; Jain, Chhavi; Rao, V. Padmanapan; Banerjee, S.

    2012-06-01

    Gold coated ZnO nanorod based biosensor has been fabricated for its glucose detecting abilities and compared with that of ZnO nanorod based biosensor. SEM images of electrochemically grown ZnO nanorods show hexagonally grown ZnO nanorods on an ITO substrate. Electrochemical analysis show that gold coated ZnO based biosensors have higher sensitivity, lower limit of detection and a wider linear range for glucose detection. The results demonstrate that gold coated ZnO nanorod based biosensors are a promising material for biosensor applications over single component ZnO nanorod based biosensor.

  15. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.; Christenson, Todd R.

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  16. Photocatalytic paper using zinc oxide nanorods

    NASA Astrophysics Data System (ADS)

    Baruah, Sunandan; Jaisai, Mayuree; Imani, Reza; Nazhad, Mousa M.; Dutta, Joydeep

    2010-10-01

    Zinc oxide (ZnO) nanorods were grown on a paper support prepared from soft wood pulp. The photocatalytic activity of a sheet of paper with ZnO nanorods embedded in its porous matrix has been studied. ZnO nanorods were firmly attached to cellulose fibers and the photocatalytic paper samples were reused several times with nominal decrease in efficiency. Photodegradation of up to 93% was observed for methylene blue in the presence of paper filled with ZnO nanorods upon irradiation with visible light at 963 Wm-2 for 120 min. Under similar conditions, photodegradation of approximately 35% was observed for methyl orange. Antibacterial tests revealed that the photocatalytic paper inhibits the growth of Escherichia coli under room lighting conditions.

  17. Optical trapping of the anisotropic crystal nanorod.

    PubMed

    Bareil, Paul B; Sheng, Yunlong

    2015-05-18

    We observed in the optical tweezers experiment that some anisotropic nanorod was stably trapped in an orientation tiled to the beam axis. We explain this trapping with the T-matrix calculation. As the vector spherical wave functions do not individually satisfy the anisotropic vector wave equation, we expand the incident and scattered fields in the isotropic buffer in terms of E→, and the internal field in the anisotropic nanoparticle in terms of D→, and use the boundary condition for the normal components of D→ to compute the T-matrix. We found that when the optical axes of an anisotropic nanorod are not aligned to the nanorod axis, the nanorod may be trapped stably at a tilted angle, under which the lateral torque equals to zero and the derivative of the torque is negative. PMID:26074566

  18. Chemical synthesis of CdS onto TiO2 nanorods for quantum dot sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Pawar, Sachin A.; Patil, Dipali S.; Lokhande, Abhishek C.; Gang, Myeng Gil; Shin, Jae Cheol; Patil, Pramod S.; Kim, Jin Hyeok

    2016-08-01

    A quantum dot sensitized solar cell (QDSSC) is fabricated using hydrothermally grown TiO2 nanorods and successive ionic layer adsorption and reaction (SILAR) deposited CdS. Surface morphology of the TiO2 films coated with different SILAR cycles of CdS is examined by Scanning Electron Microscopy which revealed aggregated CdS QDs coverage grow on increasing onto the TiO2 nanorods with respect to cycle number. Under AM 1.5G illumination, we found the TiO2/CdS QDSSC photoelectrode shows a power conversion efficiency of 1.75%, in an aqueous polysulfide electrolyte with short-circuit photocurrent density of 4.04 mA/cm2 which is higher than that of a bare TiO2 nanorods array.

  19. TAILOR-APL: An Interactive Computer Program for Individual Tailored Testing

    ERIC Educational Resources Information Center

    McCormick, Douglas J.; Cliff, Norman

    1977-01-01

    An interactive computer program for tailored testing, called TAILOR, is presented. The program runs on the APL system. A cumulative file for each examinee is established and tests are then tailored to each examinee; extensive pretesting is not necessary. (JKS)

  20. Neonates need tailored drug formulations

    PubMed Central

    Allegaert, Karel

    2013-01-01

    Drugs are very strong tools used to improve outcome in neonates. Despite this fact and in contrast to tailored perfusion equipment, incubators or ventilators for neonates, we still commonly use drug formulations initially developed for adults. We would like to make the point that drug formulations given to neonates need to be tailored for this age group. Besides the obvious need to search for active compounds that take the pathophysiology of the newborn into account, this includes the dosage and formulation. The dosage or concentration should facilitate the administration of low amounts and be flexible since clearance is lower in neonates with additional extensive between-individual variability. Formulations need to be tailored for dosage variability in the low ranges and also to the clinical characteristics of neonates. A specific focus of interest during neonatal drug development therefore is a need to quantify and limit excipient exposure based on the available knowledge of their safety or toxicity. Until such tailored vials and formulations become available, compounding practices for drug formulations in neonates should be evaluated to guarantee the correct dosing, product stability and safety. PMID:25254168

  1. Magnetic and optical properties of Mn-doped ZnO vertically aligned nanorods synthesized by hydrothermal technique

    NASA Astrophysics Data System (ADS)

    Panda, J.; Sasmal, I.; Nath, T. K.

    2016-03-01

    In this paper we have reported the synthesis of high quality vertically aligned undoped and Mn-doped ZnO single crystalline nanorods arrays on Si (100) substrates using two steps process, namely, initial slow seed layer formation followed by solution growth employing wet chemical hydrothermal method. The shapes of the as grown single crystalline nanorods are hexagonal. The diameter and length of the as grown undoped ZnO nanorods varies in the range of 80-150 nm and 1.0 - 1.4 μm, respectively. Along with the lattice parameters of the hexagonal crystal structure, the diameter and length of Mn doped ZnO nanorods are found to increase slightly as compared to the undoped ZnO nanorods. The X-ray photoelectron spectroscopy confirms the presence of Mn atoms in Mn2+ state in the single crystalline ZnO nanorods. The recorded photoluminescence spectrum contains two emissions peaks having UV exciton emissions along with a green-yellow emission. The green-yellow emissions provide the evidence of singly ionized oxygen vacancies. The magnetic field dependent magnetization measurements [M (H)] and zero field cooled (ZFC) and field cooled (FC) magnetization [M(T)] measurements have been carried out at different isothermal conditions in the temperature range of 5-300 K. The Mn doped ZnO nanorods clearly show room temperature ferromagnetic ordering near room temperature down to 5 K. The observed magnetization may be attributed to the long range ferromagnetic interaction between bound magnetic polarons led by singly charged oxygen vacancies.

  2. Nanorod-Based Fast-Response Pressure-Sensitive Paints

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy; VanderWal, Randall

    2007-01-01

    A proposed program of research and development would be devoted to exploitation of nanomaterials in pressuresensitive paints (PSPs), which are used on wind-tunnel models for mapping surface pressures associated with flow fields. Heretofore, some success has been achieved in measuring steady-state pressures by use of PSPs, but success in measuring temporally varying pressures has been elusive because of the inherent slowness of the optical responses of these materials. A PSP contains a dye that luminesces in a suitable wavelength range in response to photoexcitation in a shorter wavelength range. The luminescence is quenched by oxygen at a rate proportional to the partial pressure of oxygen and thus proportional to the pressure of air. As a result, the intensity of luminescence varies inversely with the pressure of air. The major problem in developing a PSP that could be easily applied to a wind-tunnel model and could be useful for measuring rapidly varying pressure is to provide very high gas diffusivity for rapid, easy transport of oxygen to and from active dye molecules. Most PSPs include polymer-base binders, which limit the penetration of oxygen to dye molecules, thereby reducing responses to pressure fluctuations. The proposed incorporation of nanomaterials (somewhat more specifically, nanorods) would result in paints having nanostructured surfaces that, relative to conventional PSP surfaces, would afford easier and more nearly complete access of oxygen molecules to dye molecules. One measure of greater access is effective surface area: For a typical PSP as proposed applied to a given solid surface, the nanometer-scale structural features would result in an exposed surface area more than 100 times that of a conventional PSP, and the mass of proposed PSP needed to cover the surface would be less than tenth of the mass of the conventional PSP. One aspect of the proposed development would be to synthesize nanorods of Si/SiO2, in both tangle-mat and regular- array

  3. Nanorod measurement-layer separate structure for nanorod-character measurement, simulation, and application as sensor devices

    NASA Astrophysics Data System (ADS)

    Leem, Myoung-Kun; Park, Jin-Uk; Kim, Chang-Man; Kim, Kyu-Jin; Yeom, Se-Hyuk; Choi, Woo-Youp; Kang, Won-Seok; Kim, Jae-Ho; Kang, Shin-Won

    2009-02-01

    This paper reported the simple nanorod characteristic measurement method by layer separated structure. The structures are designed by the ANSYS simulation and they are fabricated by semiconductor fabrications. In the experiment, dielectrophoresis (DEP) principle is used to assemble nanorods which are synthesized by electrochemical deposition (ECD) method. However, it is difficult to make devices without assembly process because nanorods which are synthesized by the ECD method are dispersed in the medium. Therefore, this paper was studied to design and fabricate the nanorod assembly-layer and measurement-layer separation. After assembling the nanorods, I-V characteristics of the nanorods were measured.

  4. Antifouling properties of zinc oxide nanorod coatings.

    PubMed

    Al-Fori, Marwan; Dobretsov, Sergey; Myint, Myo Tay Zar; Dutta, Joydeep

    2014-01-01

    In laboratory experiments, the antifouling (AF) properties of zinc oxide (ZnO) nanorod coatings were investigated using the marine bacterium Acinetobacter sp. AZ4C, larvae of the bryozoan Bugula neritina and the microalga Tetraselmis sp. ZnO nanorod coatings were fabricated on microscope glass substrata by a simple hydrothermal technique using two different molar concentrations (5 and 10 mM) of zinc precursors. These coatings were tested for 5 h under artificial sunlight (1060 W m(-2) or 530 W m(-2)) and in the dark (no irradiation). In the presence of light, both the ZnO nanorod coatings significantly reduced the density of Acinetobacter sp. AZ4C and Tetraselmis sp. in comparison to the control (microscope glass substratum without a ZnO coating). High mortality and low settlement of B. neritina larvae was observed on ZnO nanorod coatings subjected to light irradiation. In darkness, neither mortality nor enhanced settlement of larvae was observed. Larvae of B. neritina were not affected by Zn(2+) ions. The AF effect of the ZnO nanorod coatings was thus attributed to the reactive oxygen species (ROS) produced by photocatalysis. It was concluded that ZnO nanorod coatings effectively prevented marine micro and macrofouling in static conditions. PMID:25115521

  5. Functionalized CdS nanospheres and nanorods

    NASA Astrophysics Data System (ADS)

    Lee, Hyeokjin; Yang, Heesun; Holloway, Paul H.

    2009-12-01

    Functionalized nanoparticles are discussed. Surfaces of CdS:Mn/ZnS core/shell nanospheres (Qdots) were converted from hydrophobic to hydrophilic by growth of a SiO 2 shell. The colloidal dispersion was stabilize by adding a surfactant with a negative surface charge, and a cell-penetrating-peptide, TAT, was attached through a primary amine group. The TAT functionalized Qdots were shown to pass the blood-brain-barrier and luminescence in the infused half of the brain. In addition, nanorods of S 2- rich CdS were synthesized by reaction of excess S with Cd precursors in the presence of ethylene diamine. The photoluminescence (PL) peak from the S 2- rich CdS nanorods was broad with a maximum at ∼710 nm, which was 40 nm longer in wavelength than the PL peak from Cd 2+ rich CdS (∼670 nm) nanorods. The influence of surface electron or hole trap states on the luminescent pathway of CdS nanorods were used to explain these shifts in wavelength. Nanocrystals of Au with ∼2 nm diameters were grown on S 2- rich surfaces of CdS nanorods. Significant quenching of photoluminescence was observed from Au nanocrystals on CdS nanorods due to interfacial charge separation. Charge separation by Au nanocrystals on CdS resulted in enhanced UV photocatalytic degradation of Procion red mix-5B (PRB) dye in aqueous solution.

  6. Modulation of physical and photocatalytic properties of (Cr, N) codoped TiO{sub 2} nanorods using soft solution processing

    SciTech Connect

    Lu, Wen-Chung; Nguyen, Hoang-Diem; Wu, Chun-Yi; Chang, Kao-Shuo Yoshimura, Masahiro

    2014-04-14

    Facile polymerized complex reactions together with a hydrothermal reaction were implemented to make single crystalline TiO{sub 2} nanorods for the first time. Chromium (Cr) and nitrogen (N{sub 2}) co-doping was performed to tailor the physical properties. Transmission electron microscopy and x-ray diffraction study illustrated that highly reactive facets of (101), (111), and (001) dominated rutile TiO{sub 2} nanorods. A growth model, based on formation of complex species, was proposed to elucidate effectiveness of the soft solution processing in making TiO{sub 2} nanorods. X-ray photoelectron spectroscopy analysis and consideration of fundamentals of charge neutrality showed N{sub 2} doping could inhibit formation of Cr{sup 6+} and oxygen vacancies (V{sub O}{sup 2+}). An investigation of the photocatalytic properties exhibited high efficiency of photodegradation of methylene blue in 15 min under pH = 10, using a nanocomposite of (7% Cr, 0.0021% N) codoped and 3% Cr doped TiO{sub 2} nanorods.

  7. Citrate-Stabilized Gold Nanorods

    PubMed Central

    2015-01-01

    Stable aqueous dispersions of citrate-stabilized gold nanorods (cit-GNRs) have been prepared in scalable fashion by surfactant exchange from cetyltrimethylammonium bromide (CTAB)-stabilized GNRs, using polystyrenesulfonate (PSS) as a detergent. The surfactant exchange process was monitored by infrared spectroscopy, surface-enhanced Raman scattering (SERS), and X-ray photoelectron spectroscopy (XPS). The latter established the quantitative displacement of CTAB (by PSS) and of PSS (by citrate). The Cit-GNRs are indefinitely stable at low ionic strength, and are conducive to further ligand exchange without loss of dispersion stability. The reliability of the surface exchange process supports the systematic analysis of ligand structure on the hydrodynamic size of GNRs, as described in a companion paper. PMID:25254292

  8. Methods of making functionalized nanorods

    DOEpatents

    Gur, Ilan; Milliron, Delia; Alivisatos, A. Paul; Liu, Haitao

    2012-01-10

    A process for forming functionalized nanorods. The process includes providing a substrate, modifying the substrate by depositing a self-assembled monolayer of a bi-functional molecule on the substrate, wherein the monolayer is chosen such that one side of the bi-functional molecule binds to the substrate surface and the other side shows an independent affinity for binding to a nanocrystal surface, so as to form a modified substrate. The process further includes contacting the modified substrate with a solution containing nanocrystal colloids, forming a bound monolayer of nanocrystals on the substrate surface, depositing a polymer layer over the monolayer of nanocrystals to partially cover the monolayer of nanocrystals, so as to leave a layer of exposed nanocrystals, functionalizing the exposed nanocrystals, to form functionalized nanocrystals, and then releasing the functionalized nanocrystals from the substrate.

  9. Oxidation dynamics of aluminum nanorods

    SciTech Connect

    Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

    2015-02-23

    Aluminum nanorods (Al-NRs) are promising fuels for pyrotechnics due to the high contact areas with oxidizers, but their oxidation mechanisms are largely unknown. Here, reactive molecular dynamics simulations are performed to study thermally initiated burning of oxide-coated Al-NRs with different diameters (D = 26, 36, and 46 nm) in oxygen environment. We found that thinner Al-NRs burn faster due to the larger surface-to-volume ratio. The reaction initiates with the dissolution of the alumina shell into the molten Al core to generate heat. This is followed by the incorporation of environmental oxygen atoms into the resulting Al-rich shell, thereby accelerating the heat release. These results reveal an unexpectedly active role of the alumina shell as a “nanoreactor” for oxidation.

  10. Oxidation dynamics of aluminum nanorods

    NASA Astrophysics Data System (ADS)

    Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

    2015-02-01

    Aluminum nanorods (Al-NRs) are promising fuels for pyrotechnics due to the high contact areas with oxidizers, but their oxidation mechanisms are largely unknown. Here, reactive molecular dynamics simulations are performed to study thermally initiated burning of oxide-coated Al-NRs with different diameters (D = 26, 36, and 46 nm) in oxygen environment. We found that thinner Al-NRs burn faster due to the larger surface-to-volume ratio. The reaction initiates with the dissolution of the alumina shell into the molten Al core to generate heat. This is followed by the incorporation of environmental oxygen atoms into the resulting Al-rich shell, thereby accelerating the heat release. These results reveal an unexpectedly active role of the alumina shell as a "nanoreactor" for oxidation.

  11. InxAl1-xN chiral nanorods mimicking the polarization features of scarab beetles

    NASA Astrophysics Data System (ADS)

    Magnusson, R.; Birch, J.; Hsiao, C.-L.; Sandström, P.; Arwin, H.; Järrendahl, K.

    2015-03-01

    The scarab beetle Cetonia aurata is known to reflect light with brilliant colors and a high degree of circular polarization. Both color and polarization effects originate from the beetles exoskeleton and have been attributed to a Bragg reflection of the incident light due to a twisted laminar structure. Our strategy for mimicking the optical properties of the Cetonia aurata was therefore to design and fabricate transparent, chiral films. A series of films with tailored transparent structures of helicoidal InxAl1-xN nanorods were grown on sapphire substrates using UHV magnetron sputtering. The value of x is tailored to gradually decrease from one side to the other in each nanorod normal to its growth direction. This introduces an in-plane anisotropy with different refractive indices in the direction of the gradient and perpendicular to it. By rotating the sample during film growth the in-plane optical axis will be rotated from bottom to top and thereby creating a chiral film. Based on Muellermatrix ellipsometry, optical modeling has been done suggesting that both the exoskeleton of Cetonia aurata and our artificial material can be modeled by an anisotropic film made up of a stack of thin layers, each one with its in-plane optical axis slightly rotated with respect to the previous layer. Simulations based on the optical modeling were used to investigate how pitch and thickness of the film together with the optical properties of the constitutive materials affects the width and spectral position of the Bragg reflection band.

  12. Bio-Functional Au/Si Nanorods for Pathogen Detection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Technical Abstract Nanotechnology applications for food safety and biosecurity, especially development of nanoscale sensors for foodborne pathogen measurement are emerging. A novel bio-functional nanosensor for Salmonella detection was developed using hetero-nanorods. The silica nanorods were fabr...

  13. Nanorod Aspect Ratios Determined by the Nano-Impact Technique.

    PubMed

    Plowman, Blake J; Young, Neil P; Batchelor-McAuley, Christopher; Compton, Richard G

    2016-06-01

    The in situ electrochemical sizing of individual gold nanorods is reported. Through the combination of electrochemical dissolution and the use of a surface-bound redox tag, the volume and surface area of the nanorods are measured, and provide the aspect ratio and the size of the nanorods. Excellent independent agreement is found with electron microscopy analysis of the nanorods, establishing the application of nano-impact experiments for the sizing of anisotropic nanomaterials. PMID:27106096

  14. Manufacturing tailored property ceramic composites

    SciTech Connect

    Ewsuk, K.G.; Harrison, L.W.

    1994-11-14

    Composite materials are desirable for many advanced engineering applications where the properties of a single phase material cannot meet all of the service requirements; however, existing process technology has limited the development and commercialization of composites. Lack of reproducible sintering to high density is one of the major obstacles to commercializing ceramic composites. Final-stage, non-reactive liquid phase sintering (NLPS) theory provides metrics for sinterability that can be used as guidelines to design and manufacture dense ceramic-filled-glass (CFG) composites. Additionally, within the constraints defined by the NLPS theory, sum-property models can be used to predict CFG composite properties, and to design composites with properties tailored to specific applications. By integrating composite process models with composite property models, processable, application-tailored CFG composites for microelectronics packaging have been designed and fabricated.

  15. Tailored Ceramics for Laser Applications

    SciTech Connect

    Hollingsworth, Joel

    2007-12-10

    Transparent ceramics match or exceed the performance of single-crystal materials in laser applications, with a more-robust fabrication process. Controlling the distribution of optical dopants in transparent ceramics would allow qualitative improvements in amplifier slab design by allowing gain and loss to be varied within the material. My work aims to achieve a controlled pattern or gradient of dopant prior to sintering, in order to produce tailored ceramics.

  16. Hydroquinone Based Synthesis of Gold Nanorods.

    PubMed

    Picciolini, Silvia; Mehn, Dora; Ojea-Jiménez, Isaac; Gramatica, Furio; Morasso, Carlo

    2016-01-01

    Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag(+)) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM. PMID:27585238

  17. Electrochromic and transparent conducting oxide nanorods

    NASA Astrophysics Data System (ADS)

    Limmer, Steven J.; Takahashi, Katsunori; Cao, Guozhong

    2003-11-01

    Electrochromic materials are of interest for a wide variety of applications, such as displays and smart windows. Many electrochromic oxide materials are synthesized through sol-gel processing. We have demonstrated a general technique for the synthesis of oxide nanorods using sol electrophoretic deposition with an appropriate template. This technique can be applied for the synthesis of nanorods of electrochromic materials, such as TiO2, V2O5 and Nb2O5, with diameters of ~100 nm and a length of ~10 μm. By attaching these nanorods to a conducting substrate (such as ITO coated glass), it is possible to characterize the electrochromic behavior of these materials via UV-Vis absorbance spectroscopy. A similar technique has been used to make nanorods of the transparent conducting oxide indium tin oxide (ITO), which is often used as a working electrode in electrochromic devices. Such ITO nanorods have diameters of ~75-140 nm and lengths up to 60 μm.

  18. Growth process for gallium nitride porous nanorods

    SciTech Connect

    Wildeson, Isaac Harshman; Sands, Timothy David

    2015-03-24

    A GaN nanorod and formation method. Formation includes providing a substrate having a GaN film, depositing SiN.sub.x on the GaN film, etching a growth opening through the SiN.sub.x and into the GaN film, growing a GaN nanorod through the growth opening, the nanorod having a nanopore running substantially through its centerline. Focused ion beam etching can be used. The growing can be done using organometallic vapor phase epitaxy. The nanopore diameter can be controlled using the growth opening diameter or the growing step duration. The GaN nanorods can be removed from the substrate. The SiN.sub.x layer can be removed after the growing step. A SiO.sub.x template can be formed on the GaN film and the GaN can be grown to cover the SiO.sub.x template before depositing SiN.sub.x on the GaN film. The SiO.sub.x template can be removed after growing the nanorods.

  19. Enhanced thermal stability of Ag nanorods through capping

    SciTech Connect

    Bachenheimer, Lou; Elliott, Paul; Stagon, Stephen; Huang, Hanchen

    2014-11-24

    Ag nanorods may serve as sensors in the detection of trace amounts of chemical agents, even single molecules, through surface enhanced Raman spectroscopy (SERS). However, thermal coarsening of Ag nanorods near room temperature limits their applications. This letter proposes the use of a thin oxide capping layer to enhance the thermal stability of Ag nanorods beyond 100 °C. Using electron microscopy characterization and SERS tests, the authors show that the proposed method is effective in stabilizing both morphology and sensitivity of Ag nanorods. The results of this work extend the applicability of Ag nanorods as chemical sensors to higher temperatures.

  20. Energy transfer between a biological labelling dye and gold nanorods

    NASA Astrophysics Data System (ADS)

    Racknor, Chris; Singh, Mahi R.; Zhang, Yinan; Birch, David J. S.; Chen, Yu

    2014-03-01

    We have demonstrated energy transfer between a biological labelling dye (Alexa Fluor 405) and gold nanorods experimentally and theoretically. The fluorescence lifetime imaging microscopy and density matrix method are used to study a hybrid system of dye and nanorods under one- and two-photon excitations. Energy transfer between dye and nanorods via the dipole-dipole interaction is found to cause a decrease in the fluorescence lifetime change. Enhanced energy transfer from dye to nanorods is measured in the presence of an increased density of nanorods. This study has potential applications in fluorescence lifetime-based intra-cellular sensing of bio-analytes as well as nuclear targeting cancer therapy.

  1. Thermostructural tailoring of fiber composite structures

    NASA Technical Reports Server (NTRS)

    Acquaviva, Thomas H.

    1992-01-01

    A significant area of interest in design of complex structures involves the study of multidisciplined problems. The coordination of several different intricate areas of study to obtain a particular design of a structure is a new and pressing area of research. In the past, each discipline would perform its task consecutively using the appropriate inputs from the other disciplines. This process usually required several time-consuming iterations to obtain a satisfactory design. The alternative pursued here is combining various participating disciplines and specified design requirements into a formal structural computer code. The main focus of this research is to develop a multidiscipline structural tailoring method for select composite structures and to demonstrate its application to specific areas. The development of an integrated computer program involves the coupling of three independent computer programs using an excutive module. This module will be the foundation for integrating a structural optimizer, a composites analyzer and a thermal analyzer. With the completion of the executive module, the first step was taken toward the evolution of multidiscipline software in the field of composite mechanics. Through the use of an array of cases involving a variety of objective functions/constraints and thermal-mechanical load conditions, it became evident that simple composite structures can be designed to a combined loads environment.

  2. Nanoparticle Optics of Complex Nanorod Architectures

    SciTech Connect

    Shuford, Kevin L; Park, Sungho

    2009-01-01

    Computational studies on the optical properties of nanorods with unique compositions and exotic surface structure are presented. The distinctive architectures investigated-and compared to smooth Au rods-include Ni/Au multiblock rods and nanoporous Au rods. The surface plasmon resonances are extremely dependent upon the morphology and makeup of the nanorods. For a rod with a given aspect ratio, the resonance structure is sensitive to attributes such as the size of Ni sections of multiblock rods and pore structure of nanoporous rods. These studies indicate that control of the optical properties of nanorods is possible via characteristics other than the aspect ratio and suggest that a broader range of tunability is attainable.

  3. Xylan-Degrading Catalytic Flagellar Nanorods.

    PubMed

    Klein, Ágnes; Szabó, Veronika; Kovács, Mátyás; Patkó, Dániel; Tóth, Balázs; Vonderviszt, Ferenc

    2015-09-01

    Flagellin, the main component of flagellar filaments, is a protein possessing polymerization ability. In this work, a novel fusion construct of xylanase A from B. subtilis and Salmonella flagellin was created which is applicable to build xylan-degrading catalytic nanorods of high stability. The FliC-XynA chimera when overexpressed in a flagellin deficient Salmonella host strain was secreted into the culture medium by the flagellum-specific export machinery allowing easy purification. Filamentous assemblies displaying high surface density of catalytic sites were produced by ammonium sulfate-induced polymerization. FliC-XynA nanorods were resistant to proteolytic degradation and preserved their enzymatic activity for a long period of time. Furnishing enzymes with self-assembling ability to build catalytic nanorods offers a promising alternative approach to enzyme immobilization onto nanostructured synthetic scaffolds. PMID:25966869

  4. Collective alignment of nanorods in thin Newtonian films

    NASA Astrophysics Data System (ADS)

    Gu, Yu; Burtovyy, Ruslan; Townsend, James; Owens, Jeffery; Luzinov, Igor; Kornev, Konstantin

    2013-11-01

    We provide a complete analytical description of the alignment kinetics of magnetic nanorods in magnetic field. Nickel nanorods were formed by template electrochemical deposition in alumina membranes from a dispersion in a water-glycerol mixture. To ensure uniformity of the dispersion, the surface of the nickel nanorods was covered with polyvinylpyrrolidone (PVP). A 40-70 nm coating prevented aggregation of nanoroda. These modifications allowed us to control alignment of the nanorods in a magnetic field and test the proposed theory. An orientational distribution function of nanorods was introduced. We demonstrated that the 0.04% volume fraction of nanorods in the glycerol-water mixture behaves as a system of non-interacting particles. However, the kinetics of alignment of a nanorod assembly does not follow the predictions of the single-nanorod theory. The distribution function theory explains the kinetics of alignment of a nanorod assembly and shows the significance of the initial distribution of nanorods in the film. It can be used to develop an experimental protocol for controlled ordering of magnetic nanorods in thin films. This work was supported by the Air Force Office of Scientific Research, Grant numbers FA9550-12-1-0459 and FA8650-09-D-507 5900.

  5. Time series with tailored nonlinearities

    NASA Astrophysics Data System (ADS)

    Räth, C.; Laut, I.

    2015-10-01

    It is demonstrated how to generate time series with tailored nonlinearities by inducing well-defined constraints on the Fourier phases. Correlations between the phase information of adjacent phases and (static and dynamic) measures of nonlinearities are established and their origin is explained. By applying a set of simple constraints on the phases of an originally linear and uncorrelated Gaussian time series, the observed scaling behavior of the intensity distribution of empirical time series can be reproduced. The power law character of the intensity distributions being typical for, e.g., turbulence and financial data can thus be explained in terms of phase correlations.

  6. Time series with tailored nonlinearities.

    PubMed

    Räth, C; Laut, I

    2015-10-01

    It is demonstrated how to generate time series with tailored nonlinearities by inducing well-defined constraints on the Fourier phases. Correlations between the phase information of adjacent phases and (static and dynamic) measures of nonlinearities are established and their origin is explained. By applying a set of simple constraints on the phases of an originally linear and uncorrelated Gaussian time series, the observed scaling behavior of the intensity distribution of empirical time series can be reproduced. The power law character of the intensity distributions being typical for, e.g., turbulence and financial data can thus be explained in terms of phase correlations. PMID:26565155

  7. Multifunctional nanorods for gene delivery

    NASA Astrophysics Data System (ADS)

    Salem, Aliasger K.; Searson, Peter C.; Leong, Kam W.

    2003-10-01

    The goal of gene therapy is to introduce foreign genes into somatic cells to supplement defective genes or provide additional biological functions, and can be achieved using either viral or synthetic non-viral delivery systems. Compared with viral vectors, synthetic gene-delivery systems, such as liposomes and polymers, offer several advantages including ease of production and reduced risk of cytotoxicity and immunogenicity, but their use has been limited by the relatively low transfection efficiency. This problem mainly stems from the difficulty in controlling their properties at the nanoscale. Synthetic inorganic gene carriers have received limited attention in the gene-therapy community, the only notable example being gold nanoparticles with surface-immobilized DNA applied to intradermal genetic immunization by particle bombardment. Here we present a non-viral gene-delivery system based on multisegment bimetallic nanorods that can simultaneously bind compacted DNA plasmids and targeting ligands in a spatially defined manner. This approach allows precise control of composition, size and multifunctionality of the gene-delivery system. Transfection experiments performed in vitro and in vivo provide promising results that suggest potential in genetic vaccination applications.

  8. Bio-functional Au/Si nanorods for pathogen detection

    NASA Astrophysics Data System (ADS)

    Park, Bosoon; Fu, Junxue; Zhao, Yiping; Siragusa, Gregory R.; Cho, Yong-Jin; Lawrence, Kurt C.; Windham, William R.

    2007-09-01

    Nanotechnology applications for food safety and biosecurity, especially development of nanoscale sensors for foodborne pathogen measurement are emerging. A novel bio-functional nanosensor for Salmonella detection was developed using hetero-nanorods. The silica nanorods were fabricated by glancing angle deposition method and the gold was sputtered onto the silica nanorods. Alexa488-succinimide dye was immobilized onto the annealed Si nanorods via the attachment between dye ester and primary amine group supplied by the 3-Aminopropyltriethoxysilane. The anti-Salmonella was conjugated to gold via Dithiobis[succinimidylpropionate] self-assembly monolayer. Due to the high aspect ratio nature of the Si nanorods, hundreds or thousands of dye molecules attached to the Si nanorods produced enhanced fluorescence signal. These biologically functionalized nanorods can be used to detect Salmonella with fluorescent microscopic imaging. This new nanoscale biosensor will be able to detect other foodborne pathogenic bacteria for food safety and security applications.

  9. Hyperthermic effects of gold nanorods on tumor cells

    PubMed Central

    Huff, Terry B.; Tong, Ling; Zhao, Yan; Hansen, Matthew N.; Cheng, Ji-Xin; Wei, Alexander

    2008-01-01

    Summary Plasmon-resonant gold nanorods, which have large absorption cross sections at near-infrared (NIR) frequencies, are excellent candidates as multifunctional agents for image-guided therapies based on localized hyperthermia. The controlled modification of the nanorods' surface chemistry is of critical importance, as issues of cell-specific targeting and nonspecific uptake must be addressed prior to clinical evaluation. Nanorods coated with CTAB (a cationic surfactant used in nanorod synthesis) are internalized within hours into KB cells by a nonspecific uptake pathway, whereas the careful removal of CTAB from nanorods functionalized with folate results in their accumulation on the cell surface over the same time interval. In either case, the nanorods render the tumor cells highly susceptible to photothermal damage when irradiated at the nanorods' longitudinal plasmon resonance, generating extensive blebbing of the cell membrane at laser fluences as low as 44 W/cm2. PMID:17716198

  10. Hyperthermic effects of gold nanorods on tumor cells.

    PubMed

    Huff, Terry B; Tong, Ling; Zhao, Yan; Hansen, Matthew N; Cheng, Ji-Xin; Wei, Alexander

    2007-02-01

    Plasmon-resonant gold nanorods, which have large absorption cross sections at near-infrared frequencies, are excellent candidates as multifunctional agents for image-guided therapies based on localized hyperthermia. The controlled modification of the surface chemistry of the nanorods is of critical importance, as issues of cell-specific targeting and nonspecific uptake must be addressed prior to clinical evaluation. Nanorods coated with cetyltrimethylammonium bromide (a cationic surfactant used in nanorod synthesis) are internalized within hours into KB cells by a nonspecific uptake pathway, whereas the careful removal of cetyltrimethylammonium bromide from nanorods functionalized with folate results in their accumulation on the cell surface over the same time interval. In either case, the nanorods render the tumor cells highly susceptible to photothermal damage when irradiated at the nanorods' longitudinal plasmon resonance, generating extensive blebbing of the cell membrane at laser fluences as low as 30 J/cm2. PMID:17716198

  11. Condensation on nanorods by molecular dynamics

    NASA Astrophysics Data System (ADS)

    Suh, Donguk; Yasuoka, Kenji

    2016-06-01

    Many recent experimental studies have been conducted on constructing nanorods and nanowires to use in a wide range of applications. In this study, molecular dynamics is used to directly examine the condensation rate of nanorods and the results are compared with other basic configurations such as cubes or spheres. According to previous studies conducted by Suh and Yasuoka [J. Phys. Chem. B 115, 10631 (2011); 116, 14637 (2012)], a simple change in the configuration of the seed produces a shape effect, where the curvature of the solid seed surface directly affects the growth generating an orderly difference depending on the curvature. Nanoscale cuboids or nanorods were studied to find an aspect ratio effect when condensation occurs on the surface. Various aspect ratios were examined for different nanorod sizes over a wide range of supersaturation ratios. The results show that the growth rate of the nanorod is independent of the supersaturation ratio, which was also observed for the sphere and cube. The growth rate for the rod fell between those of the cube and the sphere, and this is due to an increase in the surface area of the nanorod compared to the cube and curvature effect in comparison with the sphere. A clear size dependence of the seed was observed, which is also similar to the cube and sphere. Furthermore, no aspect ratio influence was seen for the growth rate. This does not mean that the actual amount of condensation is the same for longer seeds, but rather from the definition of the growth rate, the amount of accumulation per unit area is the same for all seed lengths.

  12. Titania nanorods curve to lower their energy.

    PubMed

    Zhang, Hengzhong; Finnegan, Michael P; Banfield, Jillian F

    2013-08-01

    Spontaneous formation of curved nanorods is generally unexpected, since curvature introduces strain energy. However, electron microscopy shows that under hydrothermal conditions, some nanorods grown by oriented attachment of small anatase particles on {101} surfaces are curved and dislocation free. Molecular dynamics simulations show that the lattice energy of a curved anatase rod is actually lower than that of a linear rod due to more attractive long-range interatomic Coulombic interactions among atoms in the curved rod. The thermodynamic driving force stemming from lattice energy could be harnessed to produce asymmetric morphologies unexpected from classical Ostwald ripening with unusual shapes and properties. PMID:23794056

  13. Directed spatial organization of zinc oxide nanorods.

    SciTech Connect

    Simmons, Neil C.; Liu, Jun; Voigt, James A.; Hsu, Julia W. P.; Tian, Zhengrong Ryan; Matzke, Carolyn M.

    2004-09-01

    The ability to precisely place nanomaterials at predetermined locations is necessary for realizing applications using these new materials. Using an organic template, we demonstrate directed growth of zinc oxide (ZnO) nanorods on silver films from aqueous solution. Spatial organization of ZnO nanorods in prescribed arbitrary patterns was achieved, with unprecedented control in selectivity, crystal orientation, and nucleation density. Surprisingly, we found that caboxylate endgroups of {omega}-alkanethiol molecules strongly inhibit ZnO nucleation. The mechanism for this observed selectivity is discussed.

  14. Nanorods and nanotubes: Synthesis, manipulation and properties

    NASA Astrophysics Data System (ADS)

    Wong, Eric Warren

    Nanorods and nanotubes represent idealized structures for investigating phenomena associated with reduced dimensionality and are potential building blocks for nanostructured materials. Understanding their synthesis as well as physical properties is crucial if they are to form the basis for future devices. The synthesis of carbide nanotubes and nanorods is described. Also presented is a general method that combines micropatterning techniques with scanning force microscopy (SFM) to probe individual quasi-one-dimensional materials. Polycrystalline TiC and NbC nanorods, with 20-30 nm diameters and lengths exceeding 1 mum, were synthesized by reacting gaseous Ti-I or Nb-I at 550-1100sp°C with carbon nanotubes which served as structural templates. Template growth from nanotubes appears general since polycrystalline BCsb{x} and amorphous Fesb3C nanorods were produced from Bsb2Osb2 and FeClsb3, respectively. However, reaction of Si-I precursors with nanotubes or graphite above 1050sp°C resulted in single crystal SiC nanorods, with 1-20 nm diameters and 1-20 mum lengths, that grew catalytically from MoSisb2 nanoparticles by a vapor-solid mechanism. Above 1200sp°C, single crystal TiC nanorods grew from nanotubes and Ti-I or TiO by an undetermined mechanism. To probe electrical transport in carbon nanotubes, a method was devised where a static gold contact was lithographically formed with one end of a nanotube while a second dynamic contact was made by a conducting SFM probe. The conducting SFM tip can simultaneously map the topography and conductance of the nanotube. The transport properties of a series of structurally distinct nanotubes were studied and shown to sensitively depend on their structure, the presence of defects causing dramatic increases in resistivity. The mechanics of SiC nanorods and carbon nanotubes were studied using an analogous technique. An SFM tip was used to measure the forces required to bend nanobeams. The SiC nanorods had elastic moduli in close

  15. In situ formation of a ZnO/ZnSe nanonail array as a photoelectrode for enhanced photoelectrochemical water oxidation performance

    NASA Astrophysics Data System (ADS)

    Wang, Liyang; Tian, Guohui; Chen, Yajie; Xiao, Yuting; Fu, Honggang

    2016-04-01

    In this study, a ZnO/ZnSe nanonail array was prepared via a two-step sequential hydrothermal synthetic route. In this synthetic process, the ZnO nanorod array was first grown on a fluorine-doped tin oxide (FTO) substrate using a seed-mediated growth approach via the hydrothermal process. Then, the ZnO nanonail array was obtained via in situ growth of ZnSe nano caps onto the ZnO nanorod array via a hydrothermal process in the presence of a Se source. The surface morphology and amount of ZnSe grown on the surface of the ZnO nanorods can be regulated by varying the reaction time and reactant concentration. Compared with pure ZnO nanorods, this unique nanonail array heterostructure exhibits enhanced visible light absorption. The transient photocurrent condition, in combination with steady-state and time-resolved photoluminescence spectroscopy, reveals that the ZnO/ZnSe nanonail array electrode has the highest charge separation rate, highest electron injection efficiency, and highest chemical stability. The photocurrent density of the ZnO/ZnSe nanonail array heterostructure reaches 1.01 mA cm-2 at an applied potential of 0.1 V (vs. Ag/AgCl), which is much higher than that of the ZnO/ZnSe nanorod array (0.71 mA cm-2), the pristine ZnO nanorod array (0.39 mA cm-2), and the ZnSe electrode (0.21 mA cm-2), indicating its significant visible light driven activities for photoelectrochemical water oxidation. This unique morphology of nail-capped nanorods might be important for providing better insight into the correlation between heterostructure and photoelectrochemical activity.In this study, a ZnO/ZnSe nanonail array was prepared via a two-step sequential hydrothermal synthetic route. In this synthetic process, the ZnO nanorod array was first grown on a fluorine-doped tin oxide (FTO) substrate using a seed-mediated growth approach via the hydrothermal process. Then, the ZnO nanonail array was obtained via in situ growth of ZnSe nano caps onto the ZnO nanorod array via a

  16. High quality boron carbon nitride/ZnO-nanorods p-n heterojunctions based on magnetron sputtered boron carbon nitride films

    SciTech Connect

    Qian, J. C.; Jha, S. K. E-mail: apwjzh@cityu.edu.hk; Wang, B. Q.; Jelenković, E. V.; Bello, I.; Klemberg-Sapieha, J. E.; Martinu, L.; Zhang, W. J. E-mail: apwjzh@cityu.edu.hk

    2014-11-10

    Boron carbon nitride (BCN) films were synthesized on Si (100) and fused silica substrates by radio-frequency magnetron sputtering from a B{sub 4}C target in an Ar/N{sub 2} gas mixture. The BCN films were amorphous, and they exhibited an optical band gap of ∼1.0 eV and p-type conductivity. The BCN films were over-coated with ZnO nanorod arrays using hydrothermal synthesis to form BCN/ZnO-nanorods p-n heterojunctions, exhibiting a rectification ratio of 1500 at bias voltages of ±5 V.

  17. A gradient field defeats the inherent repulsion between magnetic nanorods

    PubMed Central

    Gu, Yu; Burtovyy, Ruslan; Custer, John; Luzinov, Igor; Kornev, Konstantin G.

    2014-01-01

    When controlling the assembly of magnetic nanorods and chains of magnetic nanoparticles, it is extremely challenging to bring them together side by side while keeping a desired spacing between their axes. We show that this challenge can be successfully resolved by using a non-uniform magnetic field that defeats an inherent repulsion between nanorods. Nickel nanorods were suspended in a viscous film and a non-uniform field was used to control their placement. The in-plane movement of nanorods was tracked with a high-speed camera and a detailed image analysis was conducted to quantitatively characterize the behaviour of the nanorods. The analysis focused on the behaviour of a pair of neighbour nanorods, and a corresponding dynamic model was formulated and investigated. The complex two-dimensional dynamics of a nanorod pair was analysed analytically and numerically, and a phase portrait was constructed. Using this phase portrait, we classified the nanorod behaviour and revealed the experimental conditions in which nanorods could be placed side by side. Dependence of the distance between a pair of neighbour nanorods on physical parameters was analysed. With the aid of the proposed theory, one can build different lattices and control their spacing by applying different field gradients. PMID:26064550

  18. New trend for synthesizing of magnetic nanorods with titanomaghemite structure

    NASA Astrophysics Data System (ADS)

    Saber, Osama

    2016-07-01

    This research aims at developing magnetic and optical materials through fabrication of uniform nanorods by facile and novel technique. In this trend, titanium and iron were successfully combined together forming nanorods without template or high temperature by urea hydrolysis. TEM images showed uniform and homogeneous nanorods with dimensions; 10 nm in width and 50 nm in length. In the same time, fine nanoparticles were observed around the nanorods. With further treatment for the nanorods at high temperature and pressure, FESEM images revealed that the dimensions of the rods slightly increased to be 70 nm in length and 12 nm in width with a complete disappearance of the nanoparticles. Using X-ray diffraction, thermal analyses and infrared spectra in addition to the results of the electron microscopy, the oriented attachment mechanism was suggested for the formation of titanium iron oxides nanorods. The magnetic measurements revealed that the prepared nanorods possess ferromagnetic behavior and exhibit high saturation magnetization. Also, the optical properties showed that the nanorods have high absorption in the visible region and possess low band gap energy. Finally, we concluded that it is probably the first time to prepare nanorods by urea hydrolysis. The advanced optical and magnetic properties give the prepared nanorods relevance to use as building blocks in functional nanoscale devices.

  19. Femtosecond laser fabrication of gold nanorod/polymer composite microstructures

    NASA Astrophysics Data System (ADS)

    Masui, Kyoko; Shoji, Satoru; Ushiba, Shota; Duan, Xuan-Ming; Kawata, Satoshi

    2012-10-01

    We present a fabrication method of gold nanorod/ polymer composite microstructures by means of a femtosecond near-infrared laser light. The mechanism of this method is based on a cooperation of two optical reactions; two-photon polymerization (TPP) reaction only at the surface of gold nanorods, and optical accumulation of gold nanorods in photo-polymerizable resin. Gold nanorods were mass-produced by seed mediated growth method, and were mono-dispersed in photo-resin. The wavelength of the laser light was tuned resonant to two-photon absorption of the photo-resin, and also close to a longitudinal local surface plasmon resonance (LSPR) mode of the gold nanorods. The laser light excited LSPR onto gold nanorods, resulting in the formation of thin polymer layer only at their surface through TPP. Concurrently occurring optical accumulation of gold nanorods by continuous irradiation of laser light, gold nanorods got together into focus spot. The TPP layer at the surface of gold nanorods worked as a glue to stick one another for forming their aggregated structure in micro/nano scale. By controlling the intensity and the exposure time of laser light, an optimal condition was found to induce dominant polymerization without any thermal damages. The scanning of the focus spot makes it possible to create arbitrary micro/nano structures. This method has a potential to create plasmonic optical materials by controlling the alignment of gold nanorods.

  20. Ultrasensitive Characterization of Mechanical Oscillations and Plasmon Energy Shift in Gold Nanorods.

    PubMed

    Soavi, Giancarlo; Tempra, Iacopo; Pantano, Maria F; Cattoni, Andrea; Collin, Stéphane; Biagioni, Paolo; Pugno, Nicola M; Cerullo, Giulio

    2016-02-23

    Mechanical vibrational resonances in metal nanoparticles are intensively studied because they provide insight into nanoscale elasticity and for their potential application to ultrasensitive mass detection. In this paper, we use broadband femtosecond pump-probe spectroscopy to study the longitudinal acoustic phonons of arrays of gold nanorods with different aspect ratios, fabricated by electron beam lithography with very high size uniformity. We follow in real time the impulsively excited extensional oscillations of the nanorods by measuring the transient shift of the localized surface plasmon band. Broadband and high-sensitivity detection of the time-dependent extinction spectra enables one to develop a model that quantitatively describes the periodic variation of the plasmon extinction coefficient starting from the steady-state spectrum with only one additional free parameter. This model allows us to retrieve the time-dependent elongation of the nanorods with an ultrahigh sensitivity and to measure oscillation amplitudes of just a few picometers and plasmon energy shifts on the order of 10(-2) meV. PMID:26767699