Advanced Materials Research Vols. 347-353

Abstract: A new composite electrocatalyst, well-dispersed TiO2/active carbon (AC), has been assessed with regard to its applicability for oxygen reduction in air electrodes. TiO2/AC powders were prepared by one-step vapor hydrolysis of TiCl4 with active carbon. The structure and composition of the powders were analyzed by means of XRD and FTIR, and the results showed that anatase titanium dioxide of particle size 16.5 nm was produced after calcination at 400 °C. The influences of the preparative parameters of the air electrode on its discharge performance were studied by polarization curve measurements. The terminal voltage of the air battery was maintained at above 1.05 V while the current density of the air electrodes reached 150 mA cm-2. These results show that the composite catalyst has high electrochemical activity for the oxygen reduction reaction.

Abstract: How to keep combustion stability and less carbon deposit in micro-channel for the methane wet-air auto-thermal reforming combustion technology is a hot research area all over the world now. Even if there are some literatures with respect to this area, but there are many problems to keep studying. In this paper, the effects on the carbon deposit rule, hydrogen and methane conversion characteristics under lean oxygen at pressure have been studied below 973K by thermodynamic analysis with constant feed gas mass flow. Results show that the carbon deposit increases with increasing the temperature first, and then, it decreases. At the same time, the carbon deposit always decreases with increasing reaction pressure. At the different reaction pressure, the temperature zone of carbon deposit is changed, but the upper temperature limit is around 850K. H2 mass fraction and CH4 conversion ratio are raised with increasing the temperature, decreased with increasing the pressure. Adding pressure helps to reduce carbon deposit and maintain a certain H2 mass fraction and CH4 conversion ratio. All results show the reasonable reaction pressure is 0.2MPa in micro reactor.

Abstract: Laccases (1.10.3.2, p-diphenol: dioxygen oxidoreductases) is a family of blue copper-containing oxidases that are commonly found in bacteria, fungi and plants. It is able to oxidize and degrade a variety of aromatic compounds and other organic compounds. Due to this ability, laccases can serve environmental bioremediation processes and industrial purposes. Cell-surface display of enzymes is one of the most attractive applications in yeast. It is a effective utilization to construct the whole cell biocatalyst. The cDNA sequence of Trametes sp. C30 LAC3 was optimized and synthesized according to the codon bias of Saccharomyces Italic textcerevisiae, because codon optimization has been proved to be effective to maximize production of heterologous proteins in yeast. The genes encoding galactokinase (GAL1) promoter, α-mating factor 1 (MFα1) pre-pro secretion signal, fully codon-optimized LAC3, the 320 amino acids of C terminal of α-agglutinin, alcohol dehydrogenase (ADH1) terminator and kanMX cassette were amplified and cloned into YEplac181 to construct a cell-surface display vector called pGMAAK-lac3 with α-agglutinin as an anchor. Then pGMAAK-lac3 was transformed into S. cerevisiae. The results show LAC3 was immobilized and actively expressed on S. cerevisiae. However, the substrate specifity and activity were obviously changed. The displayed LAC3 lost the activity to phenolic substrate (guaiacol) and its activity to non-phenolic substrate (ABTS) was greatly reduced. To our knowledge, this was the first attempt to construct and express laccase through cell-surface display technology.

Abstract: Activated carbon Fiber supported PtRu hollow nanospheres have been prepared by a replacement reation in a homogeneous solution with cobalt nanoparticles as sacrificial templates. The morphology, elemental composition, structure and electrocatalytic properties of the PtRu hollow nanospheres have been investigated by transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and typical electrochemical methods, respectively. The results indicate that the ACF supported PtRu hollow nanospheres show a high activity and stability for electrocatalytic oxidation of methanol as compared to co-reduced solid PtRu nanoparticles. The reasons of the high electrocatalytic activity due to the high surface area resulted from the hollow nanosphere structure with porous shell.

Abstract: In this study, we investigated a simple strategy by introducing a adhesion promoter into the electrode to improve decrease bonder content and the supercapacitor performance. The improved electrodes are characterized by scanning electron microscopy (SEM) and electrochemical measurements. According to the results, the treated activated carbon electrode retains good adhesion strength with smaller bonder content. The electrode prepared using activated carbon treated with the adhesion promoter and a bonder mass content of 7.0 % shows the best electrochemical performance. The specific capacitance reaches 347.5 F•g-1, whereas the internal resistance is 0.94 Ω.

Abstract: A novel and simple strategy by introducing a titanate coupling agent into the electrode to improve the supercapacitor performance has been developed in this study. The surface modification of the activated carbon material are conducted under neutral conditions. The improved electrodes are characterized by mechanical tests and electrochemical measurements. The obtained results reveal that the treated activated carbon electrode retains good mechanical properties with decreased bonder content. The electrode prepared using activated carbon treated with the Titanate coupling agent and a bonder mass content of 8.0 % shows the best electrochemical performance. The specific capacitance reaches 376.2 F•g-1, whereas the internal resistance is 0.91 Ω.

Abstract: In respect to conventional particle size distribution, the fractal size dimension (FSD) has become a powerful tool for characterization of particles.In this paper, we applied both the single fractal law and the bi-fractal approaches to analyze the fractal and mutifractal characteristics of the Qingshuiying coal particles in the ultra-fine pulverizing process. The relationship between FSD and the ultra-fine pulverizing time was detected and had certain guidance meaning for optimizing the operational parameters and reducing energy consumption of the ultra-fine pulverization.

Abstract: The Li[Li0.2Co0.4Mn0.4]O2 cathode material was prepared by a sol-gel method. The X-ray diffraction (XRD) spectroscopic showed that the material was a solid solution of LiCoO2 and Li2MnO3. The material showed a reversible discharge capacity of 155.6 mAhg−1 in the voltage window of 2.0-4.3 V after percharge to 4.6 V. While the material cycled in the same voltage window without precharge could only deliver capacity of 77.6 mAhg−1. This high capacity was attributed to the loss of oxygen and structural rearrangement in the precharge process.

Abstract: The Li[Li0.2Co0.4Mn0.4]O2 cathode material was prepared by a sol-gel method. Combinative X-ray diffraction (XRD) studies showed that the material was a solid solution of LiCoO2 and Li2MnO3. The material showed a reversible discharge capacity of 155.0 mAhg−1 at -20 °C, which is smaller than that at room temperature (245.5 mAhg−1). However, the sample exhibited capacity retention of 96.3 % at -20 °C, only 74.2 % at 25 °C. The good electrochemical cycle performance at low temperature was due to the inexistence of Mn3+ in the material.

Abstract: The AMPS-ID program is used to investigate optical and electrical properties of the solar cell of a-SiC:H/a-Si1-xGex:H/a-Si:H thin films. The short circuit current density, open circuit voltage, fill factor and conversion efficiency of the solar cell are investigated. For x=0.1, the conversion efficiency of the solar cell achieve maximum 9.19 % at the a-Si1-xGex:H thickness of 340 nm.