中文摘要：

采用直流电弧等离子体法结合原位钝化法制备Mg-Nb和Mg-Nb2O5复合储氢材料超细粉体,并利用ICP、XRD、TEM、P-C-T、TG-DTA等测试手段研究对比粉体的成分、相组成、微观形貌、颗粒粒径和吸放氢性能.ICP分析显示Mg-Nb粉中Nb含量高于Mg-Nb2O5粉,但均低于初始含量.XRD和TEM皆在Mg-Nb粉中发现MgNb2O3.67相,而Mg-Nb2O5中有NbO2.46新相生成.Mg-Nb粉的P-C-T曲线吸放氢平台更平坦,滞后更小;计算出Mg-Nb粉的氢化生成焓为-73.33 kJ/mol H2,低于Mg-Nb2O5粉的-82.45 kJ/mol H2.氢化后粉体的TG-DTA分析,Mg-Nb粉的放氢峰更尖锐,放氢速度更快.Mg-Nb粉体更佳的热力学和动力学性能证明钝化引入的氧化物MgNb2O3.67起到了催化作用,而Mg-Nb2O5中的NbO2.46由于含量少、分布不均匀等原因催化效果差.以上结果证明经过钝化获得氧化物的催化效果好于直接电弧蒸发.

英文摘要：

The Mg-Nb and Mg-Nb2O5 hydrogen storage composite powders were prepared through arc plasma method followed by in-situ passivation.The composition,the phase component,the morphology,the particle size and the hydrogen storage properties of two powders were systematically analyzed by using inductive coupled plasma emission spectrometer （ICP）,X-ray diffraction （XRD）,transmission electron microscopy （TEM）,pressure-composition-temperature （PCT） and thermogravimetry/differential thermal analysis （TG/DTA）techniques.ICP analyses reveal that the Nb contents of both powders reduce compared with their initial compositions.In addition,Nb content in Mg-Nb powder is higher than that in Mg-Nb2O5 powder.XRD results show that MgNb2O3.67 phase exists in Mg-Nb powder and NbO2.46 phase in Mg-Nb2O5 powder.TEM observations reveal that the MgNb2O3.67 particles are distributed more homogeneously and their particle sizes are smaller than those of the NbO2.46 particles in Mg-Nb2O5 powder.PCT analyses show that the hydrogen sorption plateaus of the Mg-Nb powder are wider and smoother with a smaller absorption/desorption gap compared to those of Mg-Nb2O5 powder.Based on Van＇t Hoff equation,the hydrogenation enthalpy of the Mg-Nb powder is determined to be-73.33 kJ/mol H2,lower than the value of -82.45 kJ/mol H2 for Mg-Nb2O5 powder.TG-DTA measurements show that the hydrogenated Mg-Nb powder has a faster desorption rate and a sharper endothermic desorption peak compared to those of the hydrogenated Mg-Nb2O5 powder.The better hydrogen storage thermodynamic and kinetic properties of Mg-Nb powder may be attributed to the catalytic effect of MgNb2O3.67 generated in passivation.In contrast,the NbO2.46 phase can be reduced during hydrogenaing.Also,it has a low content and a heterogeneous distribution in Mg-Nb2O5 powder and thus possesses a poor catalytic effect.The above results show that the arc plasma method followed by in-situ passivation is an more efficient approach to produce metal-oxide hydrogen storage composite with a