Sc对镁基储氢材料吸放氢动力学影响

发布时间：2018-01-03 04:26

本文关键词：Sc对镁基储氢材料吸放氢动力学影响　出处：《稀土》2016年03期 　论文类型：期刊论文

【摘要】：用基于密度泛函理论的第一性原理,对Sc作为催化剂对氢气在Mg(0001)表面解离和扩散性能进行了研究。首先,对Sc原子在Mg(0001)表面的稳定吸附和替代位置进行了研究,结果表明,Sc原子将替代在表面的第二层稳定。接下来有对氢气在Sc替代在第二层的Mg(0001)表面解离和扩散性能进行了研究。结果显示由于Sc的存在,氢气在其表面的解离势垒下降至0.57 e V,氢原子在其表面扩散的势垒降低至0.11 e V,利用分波态密度分析得出Sc原子d轨道上的电子对氢气在Mg表面解离起到了促进的作用;更重要的是,氢原子在Sc原子上方的hcp位向Mg内部扩散的势垒由0.69 e V下降至0.26 e V。大幅度降低氢原子向Mg内部扩散的阻力,也为氢原子向Mg内部扩散提供了更多的通道。Sc有效提高了镁基储氢材料的吸放氢动力学性能,是改善镁基储氢材料的动力学性能很好的催化剂。
[Abstract]:With the first principle based on the density functional theory of Sc as the catalyst of hydrogen in Mg (0001) surface dissociation and diffusion properties were studied. Firstly, the Sc atoms on Mg (0001) surface stable adsorption and alternative position were studied. The results show that Sc atoms will be replaced in second stable surface layer the next of hydrogen in the Sc substitution in the second tier of the Mg (0001) surface dissociation and diffusion properties were studied. The results show that due to the presence of Sc, the hydrogen dissociation barrier on the surface of e decreased to 0.57 V, the hydrogen atoms on the surface of the diffusion barrier decreased to 0.11 e V, the use of wave state density analysis of Sc D atomic orbitals on the electron of hydrogen to promote role on the surface of Mg dissociation; more importantly, the hydrogen atoms in the internal diffusion of HCP Mg orientation Sc atoms above the barrier by 0.69 e V down to 0.26 e V. lower hydrogen atoms to Mg The resistance of internal diffusion also provides more channels for the diffusion of hydrogen atoms into Mg..Sc effectively improves the kinetics of hydrogen absorption and desorption of Mg based hydrogen storage materials, and is a good catalyst for improving the dynamic properties of Mg based hydrogen storage materials.

【作者单位】：平顶山学院化学化工学院;广西科技大学生物与化学工程学院;
【基金】：河南省科技攻关项目(KJT142102310462;KJT142192310186) 河南省教育厅自然科学基金平顶山学院高层次人才基金
【分类号】：TB34
【正文快照】： 近年来,由于环境污染严重和化石能源的日渐枯竭,氢气作为清洁能源和未来替代化石能源的新型能源越来越受到关注,寻找一种经济、安全、高效的储氢材料就显得十分必要。Mg由于其储量大、成本低、储氢质量含量高(Mg H2的储氢质量比达到7.6%)等优势被认为是最具潜力的储氢材料[1,2

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