金属原子(Li/K)掺杂对NaMgH_3体系放氢性能影响的理论研究  

Theoretical Study on the Dehydrogenation from NaMgH_3 by Metal(Li/K) Doping

作　　者：陈玉红[1,2] 何开宙 张梅玲 元丽华[1] 张材荣[1,2] 

机构地区：[1]兰州理工大学,甘肃兰州730050 [2]省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050

出　　处：《稀有金属材料与工程》2018年第1期157-161,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51562022);省部共建有色金属先进加工与再利用国家重点实验室开放基金(SKLAB02014004);甘肃省高校基本科研业务费项目(05-0342);NSFC-广东联合基金(第2期)超级计算科学应用研究专项资助

摘　　要：通过密度泛函理论研究了NaMgH_3和M(Li/K)替代部分Na体系的电子结构和放氢热力学性质。计算了掺杂体系沿着4条可能的反应路径的反应焓,表明掺杂体系以反应M_xNa_(1-x)MgH_3→xMH+(1–x)NaH+Mg+H_2放氢的可能性最大。Li替代部分Na后降低了体系的反应焓,改善了体系的放氢热力学性能;而K掺杂体系的反应焓变化不明显。通过对电子态密度和键布局的分析表明:Li的掺入降低了离子对价带的贡献,同时减弱了Li与H之间的相互作用,这有利于体系放氢。计算Li在不同掺杂浓度下的反应焓,表明随着Li掺杂量的增加,掺杂体系放氢热力学性能逐步改善,但Li的掺杂量不能超过50.00%。The electronic structure and dehydrogenation properties of NaMgH3 and metal（Li/K） substitution for parts of Na have been investigated using the density functional theory. Further calculations of reaction enthalpies along four possible dehydrogenation reaction pathways indicate that reaction pathway MxNa~.xMgH3--}xMI-I＋（I-x）NaH＋Mg＋H2 is the most realistic. The Li doping in NaMgH3 decreases the value of reaction enthalpy and improves thermodynamic properties, but the K substitution has little impact on them. The electronic densities of states and the mulliken population analysis show that Li doping is of benefit to releasing H because of decreasing the contribution of H to the valence band and weakening the interaction between Li and H. The different Li doping contents of reaction enthalpies indicate that with the increase of Li content the structure presents excellent thermodynamic properties. But the Li substitution content should be less than 50.00%.

关 键 词：NaMgH3 第一性原理 掺杂 形成焓 反应焓 

分 类 号：TK91[动力工程及工程热物理]