Effect of hydrogen dilution on intrinsic a-Si:H layer between emitter and Si wafer in silicon heterojunction solar cell

In silicon heterojunction solar cells, a thin intrinsic amorphous-silicon (a-Si:H) buffer layer between a doped emitter and a c-Si wafer is essential to minimize carrier recombination. This study examines the effect of H₂ dilution on the properties of the intrinsic a-Si:H layers deposited on Si wafers by plasma-enhanced chemical vapor deposition. A H₂/SiH₄ ratio of 24 led to improvements in the quality of intrinsic a-Si:H films and in the performance of passivation compared to a-Si:H film without H₂ dilution. A high H₂-dilution ratio, however, degraded the passivation of the a-Si:H film. The Si heterojunction solar cells with an optimal intrinsic a-Si:H layer showed an efficiency of 12.3%.     

超声速来流与横向喷流干扰流场冻结流数值模拟

利用对称TVD格式和重叠网格技术数值求解NS方程及组分方程，采用单一空气组分模型和双组分冻结流模型，模拟了某导弹构形的横向喷流干扰流场，对计算结果进行了分析．     

尼龙射流冲击夹层装药的仿真研究

为实现尼龙射流对夹层装药的穿而不爆,利用非线性动力学分析软件AUTODYN-2D对尼龙射流冲击起爆夹层B炸药进行数值仿真,研究不同装药结构下尼龙射流对夹层装药的侵彻效果。结果表明,药型罩壁厚和锥角与射流u2d值成正相关关系,装药长径比与射流u2d值成负相关关系,尼龙射流冲击引爆夹层B炸药的u2d阈值约为20.939 mm3/μs2,对反爆炸式反应装甲(ERA)战斗部设计具有重要的参考价值。     

混流式喷水推进泵叶轮刮擦故障诊断方法

针对喷水推进泵的叶顶间隙过大或者过小都会影响喷水推进船航速的问题,提出一种利用泵壳体振动和输入轴力矩参量对叶轮刮擦故障进行识别的方法。在介绍混流式喷水推进泵叶轮径向摩擦振动机理的基础上,对装有2台喷泵的某高速巡逻艇的实船试航,通过获取的靠近叶轮的壳体振动信号以及输入轴力矩信号分析,得到了具体的故障特征指标。该分析结果为使用人员及时对这类异常状态做出快速、准确的判断,及时调整叶轮安装的状态以防止更大事故的发生提供了参考。     

Pt and Ru dispersed on LiCoO2 for hydrogen generation from sodium borohydride solutions

Nano-sized platinum and ruthenium dispersed on the surface LiCoO₂ as catalysts for borohydride hydrolysis are prepared by microwave-assisted polyol process. The catalysts are characterized by transmission electron microscopy (TEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). Very uniform Pt and Ru nanoparticles with sizes of <10 nm are dispersed on the surface of LiCoO₂. XRD patterns show that the Pt/LiCoO₂ and Ru/LiCoO₂ catalysts only display the characteristic diffraction peaks of a LiCoO₂ crystal structure. Results obtained from XPS analysis reveal that the Pt/LiCoO₂ and Ru/LiCoO₂ catalysts contain mostly Pt(0) and Ru(0), with traces of Pt(IV) and Ru(IV), respectively. The hydrogen generation rates using low noble metal loading catalysts, 1 wt.% Pt/LiCoO₂ and 1 wt.% Ru/LiCoO₂, are very high. The hydrogen generation rate using Ru/LiCoO₂ as a catalyst is slightly higher compared with that of Pt/LiCoO₂.     

Electrochemical hydrogen pumping using a high-temperature polybenzimidazole (PBI) membrane

Electrochemical hydrogen pumping using a high-temperature (>100 °C) polybenzimidazole (PBI) membrane was demonstrated under non-humidified and humidified conditions at ambient pressures. Relatively low voltages were required to operate the pump over a wide range of hydrogen flow rates. The advantages of the high-temperature capability were shown by operating the pump on reformate feed gas mixtures containing various amounts of CO and CO₂. Gas purity measurements on the cathode gas product were conducted and significant reductions in gas impurities were detected. The applicability of the PBI membrane for electrochemical hydrogen pumping and its durability under typical operating conditions were established with tests that lasted for nearly 4000 h.     

Influence of different ruthenium(II) bipyridyl complex on the photocatalytic H2 evolution over TiO2 nanoparticles with mesostructures

H₂ production over dye-sensitized Pt/TiO₂ nanoparticles with mesostructures (m-TiO₂) under visible light (λ > 420 nm) was investigated by using methanol as electron donors. Experimental results indicate that three types of ruthenium(II) bipyridyl complex dyes (one binuclear Ru, two mononuclear Ru), which can be attached to Pt/m-TiO₂ with different linkage modes, show different photosensitization effects due to their different coordination circumstances and physicochemical properties. The dye tightly linked with m-TiO₂ has better durability but the lowest H₂ evolution efficiency, whereas the loosely attached dyes possess higher H₂ evolution efficiency and preferable durability. It seems that the dynamic equilibrium between the linkage of the ground state dye with TiO₂ and the divorce of the oxidization state dye from the surfaces plays a crucial role in the photochemical behavior during the photocatalyst sensitization process. It is helpful to improve the H₂ evolution efficiency by enhancing the electron injection and hindering the backward transfer. The binuclear Ru(II) dye shows a better photosensitization in comparison with mononuclear Ru(II) dyes due to its large molecular area, conjugation system, and “antenna effect”, which, in turn, improve the visible light harvesting and electron transfer between the dye molecules and TiO₂.     

Chemical stability and hydrogen permeation performance of Ni–BaZr0.1Ce0.7Y0.2O3−δ in an H2S-containing atmosphere

Composite membranes based on Ni and Zr-doped BaCeO₃ are promising for hydrogen separation. Such composites show high proton conductivity and adequate chemical stability in H₂O and CO₂, but may be unstable in H₂S. In this work, the hydrogen permeation performance of Ni–BaZr_0.1Ce_0.7Y_0.2O_3−δ was measured in an H₂S-containing atmosphere at 900 °C. The hydrogen permeation flux began to degrade in 60 ppm H₂S and decreased by about 45% in 300 ppm H₂S. After hydrogen permeation tests, X-ray diffraction analysis revealed the formation of BaS, doped CeO₂, Ni₃S₂ and Ce₂O₂S. Analysis of the microstructure and phase composition, and results of thermodynamic calculations suggest that reaction between H₂S and doped BaCeO₃ caused the performance loss of the Ni–BaZr_0.1Ce_0.7Y_0.2O_3−δ.     

Amorphous Ni–S–Mn alloy as hydrogen evolution reaction cathode in alkaline medium

Amorphous Ni–S–Mn alloy electrodes were obtained by electrodeposition. The microstructure, surface morphology and composition of the new Ni–S–Mn alloy on the Ni substrate were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX). The electrochemical kinetics and mechanism of the hydrogen evolution reaction (HER) of formed electrodes were studied by measurement of the steady-state polarization. Owing to the larger exchange current densities, the lower standard reaction activity energy and a larger surface roughness, the amorphous Ni–S–Mn alloy electrode performs at a higher electrochemical activity with greater stability for the HER in 30 wt% KOH solution at various temperatures than the Ni–S alloy electrode.