A new, highly sensitive and selective hydrogen gas (H-2) sensor based on birnessite-type manganese oxide (delta-MnO2) nanoflakes was prepared. The delta-MnO2 nanoflakes sensor selectively detected H-2 with detection limits in air of 150 ppb at 200 degrees C and 7.5 ppm at room temperature. In addition, the sensor also exhibited a considerable response to H-2 in an N-2 atmosphere. The sensor rapidly responded to trace levels of H-2 gas and displayed reversible recovery, while the detected H-2 concentrations could be accurately calculated using a modified Langmuir isotherm adsorption equation. The influence of the temperature and humidity on the sensing performance of the sensor was also investigated. The mechanism of the sensor is based on the oxidation of H2O and H-2 accompanied by the formation and oxidation of MnOOH. It is believed that the low detection limit, high selectivity and fast reversible response of the delta-MnO2 nanoflake sensor are important benefits that make this sensor a promising candidate for H-2 leak detection. (C) 2014 Elsevier B.V. All rights reserved.

The high capacity of Co3O4 nanoflowers (NFs) on Ni foam as anodes in Li ion batteries is reported in this paper. The NFs grown firmly on Ni foam is convenient for the construction of lithium ion batteries without any extra electrode preparation process. The NFs presents an initial discharge capacity of 811mAh g(-1) at a current of 1 C. Our facile solvothermal film growth technique offers an exciting opportunity for growth of metal oxide nanostructures on substrates with practical application in lithium ion batteries.

Instant detection of trace-level nitroaromatic explosives is highly desirable for national security and environmental protection. In this paper, a new strategy for the construction of nitroaromatic-indicator paper was proposed based on a mixture of red emitting cysteamine modified cadmium telluride quantum dots and green emitting thioglycollic acid capped cadmium telluride quantum dots which served as the nitroaromatic sensor and reference probes, respectively. Nitroaromatic-indicator paper showed excellent response to trinitrotoluene and picric acid with visual detection limits of 1.59 and 1.16 ng mm(-2). The screening process was accomplished within half a minute. The visualization of the nitroaromatic-indicating paper was significantly enhanced when the green reference probe was used as the background. Therefore, a rapid, simple, convenient, and high selectivity paper sensor was developed for nitroaromatics.

本文依据葡萄糖在水热条件下可生成模板剂胶体碳球的原理,以葡萄糖和六水合氯化钴为原料,经180℃条件下的水热反应,然后进行热处理制备了纳米四氧化三钴空心球材料.采用X射线粉末衍射仪对产物进行了结构表征,实验表明所得四氧化三钴的晶形为面心立方结构.采用热场发射扫描电镜对产物进行了形貌分析,实验表明所得四氧化三钴的形貌为空心球,空心球的直径约为0.3~1.2μm,球壳为多孔结构.分析了水热反应时间对四氧化三钴空心结构的影响.试验证明,将水热反应从2小时延长到4小时时,产物的形貌基本保持不变.

A gas chromatography(GC) for the determination of the purity of 2,6-dichloropyrazine(DCP) was established via the study of solvent affecting the chromatographic fractionation efficiency and determination of the solvent and the optimum separation conditions used in GC analysis.The results show that choosing acetone as solvent,using DB-5capillary chromatographic column to separation,the relationship between the DCP concentration and peak area has a good linearity,the correlation coefficient is 0.9999,the relative standard deviation is less than 0.3%,and the recovery rate is 99%-102%.The method is rapid,accurate,lower toxic,and can meet the requirements of the quality control of DCP.

A WO3/TiO2 composite, hollow-sphere photocatalyst with average diameter of 320 nm and shell thickness of 50 nm was successfully prepared using a template method. UV–vis diffuse reflectance spectra illustrated that the main absorption edges of the WO3/TiO2 hollow spheres were red-shifted compared to the TiO2 hollow spheres, indicating an extension of light absorption into the visible region of the composite photocatalyst. The WO3 and TiO2 phases were confirmed by X-ray diffraction analysis. BET isotherms revealed that the specific surface area and average pore diameter of the hollow spheres were 40.95 m2/g and 19 nm, respectively. Photocatalytic experiments indicate that 78% MB was degraded by WO3/TiO2 hollow spheres under visible light within 80 min. Under the same conditions, only 24% MB can be photodegraded by TiO2. The photocatalytic mineralization of MB, catalyzed by TiO2 and WO3/TiO2, proceeded at a significantly higher rate under UV irradiation than that under visible light, and more significant was the increase in the apparent rate constant with the WO3/TiO2 composite semiconductor material which was 3.2- and 3.5-fold higher than with the TiO2 material under both UV and visible light irradiation. The increased photocatalytic activity of the coupled nanocomposites was attributed to photoelectron/hole separation efficiency and the extension of the wavelength range of photoexcitation.

Novel large-scale Co3O4 nanoflower (NF) structures on Ni foam are prepared for the first time via a general two-step synthesis. Through a controllable solvothermal process and hereafter with a post-calcination process in air, the NFs have been grown firmly on Ni foam, which is convenient for the construction of supercapacitors without any extra electrode preparation process. The pore sizes and the amount of Co3O4 NFs can be tuned through different post-calcination and solvothermal conditions, respectively. The electrochemical properties of the NFs are tested by cyclic voltammetry, galvanostatic charge–discharge in 6.0M KOH solution. The results show that the NFs can have a specific capacitance of 1936.7Fg−1 at a current density of 0.2Ag−1 and a capacity retention of 78.2% after 1000 cycles at a current density of 3Ag−1 (1309.4Fg−1). The Co3O4 NFs grown on Ni foam with large area and superior electrochemical performance have great potential application in supercapacitors.

To study and explore the new acid electrolyte rechargeable zinc-air battery,our research used titanium plates for zinc anode –carriers,through the linear scan curve,SEM,metallographic analysis and charge methods to test their performance,the effect of acidity and current density on zinc deposition,and explore the best solution ratio and the suitable current density under the acid environment.At ambient temperature,acid concentration of 1.0 mol/L conditions,the most appropriate conditions for the deposition of zinc are as follows:50 mA/cm2 of current density,and deposition voltage platforms for titanium substrate ranged from 3.0 to 3.1 V.Additionally,deposition layers are uniform,with no obvious dendrite and deformation.After six cycles deposition and dissolution of the zinc on titanium substrate,there is higher than 85 percent of the current efficiency,therefore titanium plates are proved suitable zinc-carriers for the new acid rechargeable zinc-air battery.

Co3O4 thin film is synthesized on ITO by a chemical bath deposition. The prepared Co3O4 thin film is characterized by X-ray diffraction, and scanning electron microscopy. Electrochemical capacitive behavior of synthesized Co3O4 thin film is investigated by cyclic voltammetry, constant current charge/discharge and electrochemical impedance spectroscopy. Scanning electron microscopy images show that Co3O4 thin film is composed of spherical-like coarse particles, together with some pores among particles. Electrochemical studies reveal that capacitive characteristic of Co3O4 thin film mainly results from pseudocapacitance. Co3O4 thin film exhibits a maximum specific capacitance of 227Fg−1 at the specific current of 0.2Ag−1. The specific capacitance reduces to 152Fg−1 when the specific current increases to 1.4Ag−1. The specific capacitance retention ratio is 67% at the specific current range from 0.2 to 1.4Ag−1.

Free-standing and well-ordered TiO2 membranes were prepared by two-step anodization in F−-containing ethylene glycol electrolytes at voltage of 60V. It was found that the ordering of TiO2 membranes was significantly improved after the second anodization process. The initially closed bottom side of TiO2 membranes was opened through chemical etching to obtain two-end opened TiO2 membranes. Using the two-end opened membranes as template, dense NiTiO3/TiO2 nanotubes were successfully prepared for the first time by a sol–gel method. The microstructure and morphologies of the samples were characterized by scanning and the transmission electron microscopy techniques.