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He W.,Xuchang University | He W.,U.S. Food and Drug Administration | Kim H.-K.,U.S. Food and Drug Administration | Wamer W.G.,U.S. Food and Drug Administration | And 3 more authors.
Journal of the American Chemical Society | Year: 2014

Semiconductor nanostructures with photocatalytic activity have the potential for many applications including remediation of environmental pollutants and use in antibacterial products. An effective way for promoting photocatalytic activity is depositing noble metal nanoparticles (NPs) on a semiconductor. In this paper, we demonstrated the successful deposition of Au NPs, having sizes smaller than 3 nm, onto ZnO NPs. ZnO/Au hybrid nanostructures having different molar ratios of Au to ZnO were synthesized. It was found that Au nanocomponents even at a very low Au/ZnO molar ratio of 0.2% can greatly enhance the photocatalytic and antibacterial activity of ZnO. Electron spin resonance spectroscopy with spin trapping and spin labeling was used to investigate the enhancing effect of Au NPs on the generation of reactive oxygen species and photoinduced charge carriers. Deposition of Au NPs onto ZnO resulted in a dramatic increase in light-induced generation of hydroxyl radical, superoxide and singlet oxygen, and production of holes and electrons. The enhancing effect of Au was dependent on the molar ratio of Au present in the ZnO/Au nanostructures. Consistent with these results from ESR measurements, ZnO/Au nanostructures also exhibited enhanced photocatalytic and antibacterial activity. These results unveiled the enhanced mechanism of Au on ZnO and these materials have great potential for use in water purification and antibacterial products. © 2013 American Chemical Society.

Liu R.,California Institute of Technology | Zheng Z.,Energy Micro | Zheng Z.,Xuchang University | Spurgeon J.,California Institute of Technology | And 2 more authors.
Energy and Environmental Science | Year: 2014

An important approach for solving the world's sustainable energy challenges is the conversion of solar energy to chemical fuels. Semiconductors can be used to convert/store solar energy to chemical bonds in an energy-dense fuel. Photoelectrochemical (PEC) water-splitting cells, with semiconductor electrodes, use sunlight and water to generate hydrogen. Herein, recent studies on improving the efficiency of semiconductor-based solar water-splitting devices by the introduction of surface passivation layers are reviewed. We show that passivation layers have been used as an effective strategy to improve the charge-separation and transfer processes across semiconductor-liquid interfaces, and thereby increase overall solar energy conversion efficiencies. We also summarize the demonstrated passivation effects brought by these thin layers, which include reducing charge recombination at surface states, increasing the reaction kinetics, and protecting the semiconductor from chemical corrosion. These benefits of passivation layers play a crucial role in achieving highly efficient water-splitting devices in the near future. This journal is © the Partner Organisations 2014.

Feng Z.-B.,Xuchang University | Feng Z.-B.,CAS Wuhan Institute of Physics and Mathematics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

We propose a potentially practical scheme for quantum state transfer between a Cooper-pair box circuit and an electron spin ensemble of diamond nitrogen-vacancy (NV) centers. Both subsystems are placed into a common circuit QED and can be modeled as effective three-level subsystems under the appropriate external biases. Due to significant suppression of the photon decay, the robust state transfer between the two subsystems can be accomplished by using the technique of stimulated Raman adiabatic passage by individual microwave pulses, where a superconducting coplanar resonator serves as the quantum data bus. Numerical simulations show that the present scheme could offer a viable route towards robust quantum state transfer in hybrid solid-state systems. © 2015 American Physical Society.

We have developed hexadecyl trimethyl ammonium bromide (CTAB) functionalized graphene oxide (GO)/multiwalled carbon nanotubes (MWNTs) modified glassy carbon electrode (CTAB-GO/MWNT) as a novel system for the simultaneous determination of dopamine (DA), ascorbic acid (AA), uric acid (UA) and nitrite (NO2 -). The combination of graphene oxide and MWNTs endow the biosensor with large surface area, good biological compatibility, electricity and stability, high selectivity and sensitivity. In the fourfold co-existence system, the linear calibration plots for AA, DA, UA and NO2 - were obtained over the range of 5.0-300μM, 5.0-500μM, 3.0-60μM and 5.0-800μM with detection limits of 1.0μM, 1.5μM, 1.0μM and 1.5μM, respectively. In addition, the modified biosensor was applied to the determination of AA, DA, UA and NO2 - in urine samples by using standard adding method with satisfactory results. © 2014 Elsevier B.V.

Yidong Z.,Xuchang University
Industrial Lubrication and Tribology | Year: 2012

Purpose - The purpose of this paper is to prove the self-repairing Cu film of Cu-DDP additive in base lubricating oil. Design/methodology/approach - Cu nanoparticles coated with dialkydithiophosphate (Coded as Cu-DDP) were synthesized ITin situ/IT by redox method. The size and structure of Cu-DDP were characterized using transmission electronic microscopy (TEM) and electronic diffraction (ED) analysis. The self-repairing performance of Cu-DDP as additive in base lubricating oil was evaluated by MRH-3 stock-on-ring testing machine. Scanning electronic microscopy (SEM), UMT-2 tribometer, X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectrum (EDS) were used to study the self-repairing Cu film on the stock. Findings - The test results showed that the modified Cu-DDP additive in base lubricating oil exhibited excellent anti-wear and friction-reducing properties, as well as good self-repairing performance. Research limitations/implications - The thickness of the self-repairing Cu film was unknown, and the relationship between thickness of the Cu film and load, time, rotation velocity was still necessary to investigate. Practical implications - The Cu-DDP additive was involved P and S elements, therefore, it is still promising to seek environment friendly additive without P and S elements. Originality/value - For the first time, MRH-3 stock-on-ring testing machine, Scanning electronic microscopy (SEM), UMT-2 tribometer, X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectrum (EDS) were widely used to study the self-repairing Cu film on the stock. © 2012 Emerald Group Publishing Limited. All rights reserved.

Feng Z.-B.,Xuchang University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

In this Brief Report, we propose a theoretical scheme to transfer quantum states between superconducting charge qubits and semiconductor spin qubits in a circuit QED device. Under dispersive conditions, resonator-assisted state transfer between qubits can be performed controllably only by addressing the flux bias applied to the charge qubits. The low infidelity and existing advantages show that the proposal may provide an effective route toward scalable quantum-information transfer with solid-state hybrid qubits. © 2012 American Physical Society.

The present study was aimed to improve the method for detecting Mycobacterium tuberculosis complex recently reported on Letters in Applied Microbiology. Eriochrome black T (EBT) was added to the reaction system of LAMP, due to complexation of EBT with magnesium ions, the color of reaction solution was red at beginning, when the reaction was in process, the precipitate of magnesium ions and pyrophosphate ions formed, EBT lost magnesium ions, the color of reaction solution became sky blue from red gradually, and the method exhibits a high sensitivity of 8 fg/μL. The improved LAMP assay can detect Mycobacterium tuberculosis complex rapidly, sensitively and visually, the method developed in this study had solved the "bottleneck" in popularization and application of LAMP technology, which had not only avoided aerosol pollution but also solved the false positive problem caused by primer dimers. © (2014) Trans Tech Publications, Switzerland.

Yang Y.J.,Xuchang University | Zi J.,Xuchang University | Li W.,Xuchang University
Electrochimica Acta | Year: 2014

Flower-like CuS nanoparticles (NPs) were synthesized with a simple and mild hydrothermal method. XRD analysis indicated that the product is pure hexagonal phase CuS. The morphology of the particles was studied by TEM. The electrode modified with CuS nanoflowers showed excellent electrocatalytic activities to the oxidation of glucose and reduction of hydrogen peroxide in pH 7.2 phosphate buffer. It is the first reported copper sulfide based sensor of both glucose and hydrogen peroxide. Electrochemical analysis of the particulate CuS for detecting H2O2 and glucose is described, showing remarkable sensitivity in both cases. The estimated detection linear ranges and sensitivities for H2O2 (1 × 10-6-1 × 10-4 M, 3.64 × 104 μA M-1) and glucose (1 × 10-5 M-1 × 10-2 M, 5.86 × 103 μA M-1) suggest that the response for H 2O2 detection is higher than that for glucose detection. The good analytical performance makes CuS NPs/chitosan modified glassy carbon electrode (CuS/CS/GCE) a promising electrochemical sensor for glucose and hydrogen peroxide. © 2013 Elsevier Ltd.

Zhang Y.,Xuchang University
Applied Surface Science | Year: 2015

In this work, NiO coating was fabricated by magnetron sputtering method on quartz and indium tin oxide (ITO) substrates in an inert gas ambient of Ar followed by a thermal oxidation process in air at 400 °C for 2 h. The NiO coating was analyzed by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and UV-vis spectrometer. A preliminary photovoltaic performance measurement of the as-prepared device (ITO/NiO/poly-TPD/PC71BM/Al) shows a short circuit current density (Jsc) of 5.6 mA cm-2 and power conversion efficiency (PCE) of 1.5% under an illumination of 100 mW cm-2. The PCE of device with NiO HTLs was ca. 20% higher than those of the devices based on PEDOT:PSS hole transport layers (HTLs). The thermal oxidation fabricated NiO coating may provide an excellent route to fabricate other NiO-based optoelectronic devices. © 2015 Elsevier B.V. All rights reserved.

Zhang Y.,Xuchang University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2015

(Figure Presented) In this work, NiO nanowires have been synthesized by a hydrothermal reaction of NiCl2 with Na2C2O4 in the presence of ethylene glycol at 180°C for 12 h, then calcinated at 400°C for 2 h. The NiO nanowires were analyzed by means of scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The resulting current-voltage (I-V) characteristics of the NiO nanowires exhibited a clear rectifying behavior. This rectify behavior was attributed to the formation of a Schottky contact between Au coated atomic force microscopy (AFM) tip and NiO nanowires (nano-M/SC) which was dominated by the surface states in NiO itself. Photo-assisted conductive AFM (PC-AFM) was used to demonstrate how the I-V characteristics are influenced by the surface states. Our I-V results also showed that the nano-M/SCs had a good photoelectric switching effect at reverse bias. © 2015 Elsevier B.V. All rights reserved.

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