具可变价态稀土氧化物对Mg2Ni合金储氢性能的催化作用  

Catalytic effect of rare earth oxides with variable valences on hydrogen storage properties of Mg2Ni alloy

作　　者：张国芳[1] 孙涵丰 许剑轶[1] 张羊换[1] ZHANG Guo-fang;SUN Han-feng;XU Jian-yi;ZHANG Yang-huan(School of Materials and Metallurgy,Inner Mongolia Universityof Science and Technology,Baotou 014010,Inner Mongolia,China)

机构地区：[1]内蒙古科技大学材料与冶金学院

出　　处：《材料工程》2019年第10期90-96,共7页Journal of Materials Engineering

基　　金：国家自然科学基金(51962028,51501095);内蒙古自然科学基金(2017MS(LH)0516,2017MS(LH)0519,2017BS0504);内蒙古科技大学创新基金-优秀青年科学基金(2018YQL02)

摘　　要：采用球磨法制备Mg2Ni-Ni-5%RExOy(CeO2,Nd2O3,Tb4O7)复合材料。通过XRD,SEM,面扫描能谱分析,电化学及动力学测试系统研究材料的组织及储氢性能。结果表明:添加稀土氧化物后复合材料的结晶程度降低,稀土氧化物催化剂在合金表面分布均匀。复合材料的最大放电容量明显提高,含Tb4O7样品室温下最大放电容量达871mAh·g-1,且具有较高循环稳定性。CeO2及Tb4O7催化剂可有效提高合金电极表面电荷转移能力,增大氢原子在合金内部的传输速率。稀土氧化物催化剂还可提高复合材料的气态吸氢容量,其中含Tb4O7样品的吸氢量最高,在250℃时吸氢量达到2.02%(质量分数),但在较低温度时吸氢速率稍慢。稀土氧化物的催化作用主要与稀土离子的变价特性有关,离子的易变价性越强,则催化活性越高。催化活性由大到小的顺序为Tb4O7>CeO2>Nd2O3。Mg2Ni-Ni-5%RExOy(CeO2,Nd2O3,Tb4O7)composites were synthesized via ball milling method.The microstructure and hydrogen storage properties of the materials were analyzed systematically by XRD,SEM,EDS,the electrochemical and kinetic measurements.The results show that the crystallinities of the composites with rare earth oxides decrease,and the distribution of the rare earth oxide catalysts on the surface of alloys is uniform.The maximum discharge capacities of the composites with rare earth oxides rise evidently,the discharge capacity of the sample containing Tb4O7 reaches to 871mAh·g^-1 at room temperature,and the composites can also keep higher cycling stability.The CeO2 and Tb 4O7 catalysts can enhance the abilities of charge transfer on the surface of alloys,and improve the transmission rate of H atoms in the bulk of Mg2Ni alloy obviously.The rare earth oxides catalysts can also increase the gaseous hydrogen absorption capacity.The hydrogen storage capacity of the sample with Tb 4O7 reaches tO2.02%(mass fraction)at 250℃,which is the maximum hydrogen absorption capacity among these samples,but the hydriding rate is relatively slow at lower temperature.The catalytic effect of the rare earth oxides is mainly related to the changeable valences of the rare earth ions,that is,the more likely of the valences change of the ions,the better the catalytic activities exhibit.The catalytic activities in descending order are Tb 4O7,CeO2 and Nd 2O3.

关 键 词：稀土氧化物 Mg2Ni合金 电化学性能 动力学性能 催化作用 

分 类 号：TG139.7[一般工业技术—材料科学与工程]