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51.
Xiaofeng Cui Guiyuan Jiang Ming Zhu Zhen Zhao Luchao Du Yuxiang Weng Chunming Xu Dekai Zhang Quanlai Zhang Yuechang Wei Aijun Duan Jian Liu Jinsen Gao 《International Journal of Hydrogen Energy》2013
Solar driven semiconductor photocatalytic water splitting to produce hydrogen is an extremely charming process by storing photon energy in chemical bonds. In the present study, composite semiconductor TiO2/CdS was structured into uniform and porous double-shelled hollow sphere with cocatalyst platinum selectively loaded onto the internal wall. The SEM, TEM, STEM, XRD, BET and EDS elemental distribution etc. were employed to evidence the formation of the targeted photocatalyst. It was demonstrated that the material has a high efficiency of visible-light-driven hydrogen evolution (296 μmol·h−1/10 mg) with an apparent quantum efficiency (QE) of 14.5% at wavelength of 420 nm. Comparative experiment analysis and time-resolved infrared absorption study suggested that the high photocatalytic activity of the catalyst is attributed to the vectorial electron transfer (CdS → TiO2 → Pt) and the spatial separation of reduction and oxidation active surfaces achieved by the special morphology. 相似文献
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Hong Rok Kim Jayeeta Chattopadhyay Jae Ik Son Daewon Pak 《Korean Journal of Chemical Engineering》2008,25(4):775-779
Pure TiO2 hollow spheres were prepared by using poly(styrene-methacrylic acid) latex particles as template; thereafter, titania hollow
spheres were coated by platinum with an appropriate amount of choloroplatinic acid solution to obtain Pt/TiO2 catalysts. The morphology and structure of nonstructural Pt/TiO2 hollow spheres were characterized by BET, XRD, TGA, SEM and TEM analysis. In the samples, a remarkably uniform layer of Pt
consisting of particles from 5 to 70 nm in size was formed over TiO2 hollow spheres. We found the electrocatalytic nature of the samples by cyclic voltammetric experiment in acidic solution.
The anodic peak current density of 20 wt% Pt-loaded TiO2 hollow particles was observed 2.5 times higher than that of 5 wt% Pt/TiO2 in the same experimental condition. Also, the anodic current density of 20 wt% Pt/TiO2 hollow spheres calcined at various temperatures followed the order: 400 °C≈500 °C>600 °C. The electrocatalytic activity of
the Pt-loaded TiO2 hollow spheres depends on the amount of atomic platinum present in the sample; a higher concentration of platinum results
in a larger current density value in anodic sweep, resulting in more oxygen production during electrolysis. Pt/TiO2 hollow sphere catalysts have also shown long term electrocatalytic stability in acidic media. 相似文献
54.
根据超塑成形的工艺要求,利用ANSYS/LS-DYNA有限元软件对空心风扇叶片成形过程进行数值模拟分析,以此研究不同的芯板厚度对超塑成形结果的影响.分析的结果表明:选取的三种厚度的芯板里,当厚度为0.8mm时,塑性变形最均匀,成形效果最好. 相似文献
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分析了常规钢锭与无帽口钢锭制作筒类锻件的特点。明确指出无帽口钢锭锻件的优势:提高了钢锭利用率和锻件合格率,有效降低了冶炼和锻造成本,生产效率显著提高。 相似文献
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Synthesis and in vitro bioactivity of novel mesoporous hollow bioactive glass microspheres 总被引:1,自引:0,他引:1
The remarkable tissue-repairing bioactivity and biocompatibility of bioactive glass make it suitable for a wide range of applications. Here, novel mesoporous hollow bioactive glass microspheres (MHBGMs) with a uniform diameter range of 2-5 µm were prepared by a sol-gel method. Structural characterization indicated that the shell of hollow sphere had a mesopore size range between 2 and 10 nm and a thickness about 500 nm. The in vitro bioactivity test indicated that the novel structure exhibited high in vitro bioactivity. The uniform microspherical morphology and mesoporous hollow structure of MHBGMs, together with their high bioactivity, turn them into a good candidate as an injectable and drug-loading biomaterial for in vivo tissue regeneration and drug control release. 相似文献
59.
The hollow cylinder shear test is somewhat controversial due to its non-uniform stresses and strains, and has been analyzed by simple theoretical methods and two-dimensional FE calculations. In this paper, the hollow cylinder test under strain control was carried out numerically by treating the specimen as a three-dimensional initial-boundary value problem considering the inertial forces. At first, besides the known nonuniform strain, the non-uniformities of excess pore water pressure and overconsolidation ratio have been shown to benefit from a soil–water coupled analysis that employs the SYS Cam-clay model. Then, the influence of the specimen geometries, including wall thicknesses, heights and outer diameters on the non-uniformity was investigated sequentially. A new method for evaluating non-uniformity was proposed, which is suitable for the three-dimensional analysis. The response under a uniform deformation field, which is indicated by “the perfect path”, was presented to draw a comparison with the apparent behaviors, with non-uniformities taken into consideration. It should be noted that there is a critical height to prevent failure at the specimen ends according to the apparent behavior. Finally, the torque-controlled experiment indicated that 4 ribs could not transfer the torque reliably while 6 or 8 ribs were feasible. 相似文献
60.