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A CdS/reduced graphene oxide (RGO)/ZnO nanowire array (NWAs) heterostructure is designed, which exhibits enhanced photoelectrochemical (PEC) activity compared to pure ZnO, RGO/ZnO, and CdS/ZnO. The enhancement can be attributed to the synergistic effect of the high electron mobility of ordered 1D ZnO NWAs, extended visible-light absorption of CdS nanocrystals, and the formed type II band alignment between them. Moreover, the incorporation of RGO further promotes the charge carrier separation and transfer process due to its excellent charge collection and shuttling characteristics. Subsequently, the CdS/RGO/ZnO heterostructure is successfully utilized for the PEC bioanalysis of glutathione at 0 V (vs Ag/AgCl). The self-powered device demonstrates satisfactory sensing performance with rapid response, a wide detection range from 0.05 mm to 1 mm, an acceptable detection limit of 10 μm, as well as certain selectivity, reproducibility, and stability. Therefore, the CdS/RGO/ZnO heterostructure has opened up a promising channel for the development of PEC biosensors., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Modulation of broadband light trapping through assembly of 3D structures and modification with narrow band-gap semiconductors provide an effective way to improve the photoelectrochemical (PEC) performance. Here, 3D-branched ZnO nanowire arrays (NWAs) modified with cadmium sulfide (CdS) nanoparticles are designed and synthesized via solution chemical routes. The 3D-branched ZnO NWA-CdS nanoparticle photoanodes show an excellent PEC performance in UV and visible region and the maximum photo-to-hydrogen conversion efficiency reaches to 3.1%. The high performance of 3D-branched ZnO NWA-CdS composites is mainly attributed to the excellent carrier collection capability and high light-trapping ability of 3D-branched ZnO NWAs as well as the excellent photocatalytic activity of CdS nanoparticles in the visible region. In addition, the photocorrosion mechanism of 3D-branched ZnO NWA-CdS photoanodes is systematically investigated, and a protective TiO2 layer is deposited onto the photoanodes to elevate the PEC stability. The results benefit a deeper understanding of the role of 3D-branched structures decorated with narrow band-gap semiconductors in solar water splitting. [ABSTRACT FROM AUTHOR]

In this work, zinc oxide (ZnO) nanowires-based electrochemical biosensor is designed and fabricated for the detection of L-lactic acid. ZnO nanowires were successfully synthesized via the chemical vapor deposition method. The morphology and structure of the prepared products were characterized, and the average diameter of synthesized ZnO samples was 500 nm. The fluorescence characterization was performed to verify the immobilization of lactate oxidase onto the ZnO surface. Biosensors based on large-area ZnO nanowires were then constructed, and a series of electrochemical experiments showed that ZnO could provide the efficient electron transfer channel between the enzymic active sites and the electrode surface. The proposed electrochemical biosensor exhibited a sensitivity of 15.6 µA cm mM, a wide linear range of 12 µM-1.2 mM with a low-detection limit of 12 µM for L-lactic acid detection. This study has indicated the potential applications for ZnO nanowires to construct the simple and economic nano-bio devices for the detection of biological species. [ABSTRACT FROM AUTHOR]

We describe the use of individual zinc oxide (ZnO) micro/nanowires in an electrochemical biosensor for uric acid. The wires were synthesized by chemical vapor deposition and possess uniform morphology and high crystallinity as revealed by scanning electron microscopy, X-ray diffraction, and photoluminescence studies. The enzyme uricase was then immobilized on the surface of the ZnO micro/nanowires by physical adsorption, and this was proven by Raman spectroscopy and fluorescence microscopy. The resulting uric acid biosensor undergoes fast electron transfer between the active site of the enzyme and the surface of the electrode. It displays high sensitivity (89.74 μA cm mM) and a wide linear analytical range (between 0.1 mM and 0.59 mM concentrations of uric acid). This study also demonstrates the potential of the use of individual ZnO micro/nanowires for the construction of highly sensitive nano-sized biosensors. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A ZnO nanowire (NW) array ultraviolet photodetector (PD) with Pt Schottky contacts has been fabricated on a glass substrate. Under UV light illumination, this PD showed a high photo-to-dark current ratio of 892 at 30 V bias. Interestingly, it was also found that this PD had a high sensitivity of 475 without external bias. This phenomenon could be explained by the asymmetric Schottky barrier height (SBH) at the two ends causing different separation efficiency of photogenerated electron–hole pairs, which resulted in the formation of photocurrent. It is anticipated to have potential applications in self-powered UV detection field. [Copyright &y& Elsevier]

Abstract: Schottky-barrier ultraviolet (UV) detectors based on ZnO-nanowires (NWs) were fabricated with Pt as electrodes in this investigation. The ZnO NWs synthesized by the hydrothermal method were characterized by field-emission scanning electron microscopy (FE-SEM), Raman and PL spectroscopy. Photoelectric properties under 254 and 365 nm UV light were investigated. It is found that the photo-response properties of the devices under 365 nm UV light are better than those under 254 nm UV light, which is further illustrated by light transmission theory, energy-band diagram and absorption spectra. The results demonstrate that ZnO NWs detectors with selectivity to near-UV (NUV) light are promising candidates in photoelectric devices. [Copyright &y& Elsevier]

Abstract: Qualitative and quantitative detection of biological and chemical species is crucial in many areas, ranging from clinical diagnosis to homeland security. Due to the advantages of ultralow detection limit, label-free, fast readout and easy fabrication over the traditional detection systems, semiconductor nanowire based electronic devices have emerged as a potential platform. In this paper, we fabricated a single ZnO nanowire-based biologically sensitive field-effect transistors (bioFETs) for detection of different concentrations of uric acid solution at the same time. The addition of uric acid with the concentrations from 1pM to 0.5mM resulted in the electrical conductance changes of up to 227nS, and the response time turns out to be in the order of millisecond. The ZnO NW biosensor could easily detect as low as 1pM of the uric acid with 14.7nS of conductance increase, which implied that the detection limit of the biosensor can be as low as 1pM. [Copyright &y& Elsevier]

The fatigue behavior of ZnO nanowires(NWs) and microwires wassystematically investigated with in situ transmission electron microscopyelectromechanical resonance method. The elastic modulus and mechanicalquality factors of ZnO wires were obtained. No damage or failure wasfound in the intact ZnO wires after resonance for about 108–109cycles, while the damaged ZnO NW under electronbeam (e-beam) irradiation fractured after resonance for seconds. Theresearch results will provide a useful guide for designing, fabricating,and optimizing electromechanical nanodevices based on ZnO nanomaterials,as well as future applications. [ABSTRACT FROM AUTHOR]