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。 Based on the first principle of density functional theory (DFT), the dissociation and diffusion of hydrogen on Mg (0001) surface were studied using Sc as a catalyst. First, the stable adsorption and substitution positions of Sc atoms on the Mg (0001) surface were studied. The results show that Sc atoms will be replaced instead of being stable at the second layer of the surface. Next, the dissociation and diffusion behavior of hydrogen on the Mg (0001) surface of the second layer with substitution of Sc for hydrogen was investigated. The results show that due to the existence of Sc, the dissociation barrier of hydrogen decreases to 0.57 eV on its surface, and the barrier of diffusion of hydrogen on its surface decreases to 0.11 eV. Of the electrons on the Mg surface dissociation has played a catalytic role; more importantly, hydrogen atoms in the Sccp above the hcp position within the Mg diffusion barrier from 0.69 eV down to 0.26 eV. Drastically reduces the resistance of hydrogen atoms to diffuse inside Mg, and provides more channels for diffusion of hydrogen atoms into Mg. Sc effectively enhances the hydrogen absorption and desorption kinetics of Mg-based hydrogen storage materials and is a good catalyst for improving the kinetic properties of Mg-based hydrogen storage materials.