氢分子在贮氢材料Li2MgN2H2表面的吸附与解离

Adsorption and Dissociation of Molecular H2 on Li2MgN2H2 Surface

摘要:

采用第一性原理计算方法研究了Li-Mg-N-H体系贮氢材料的放氢产物Li2MgN2H2的吸氢反应过程中的过渡态、表面电子态密度和表面能。结果表明：氢分子在Li2MgN2H2低指数表面中最低能量(100)表面的Mg-Mg-Li穴位吸附位置能够形成最稳定的吸附结构并发生解离，氢分子吸附能为–0.1898 eV，解离能约为0.84 eV (81 kJ/mol)，表明该反应所需的反应活化能仍较高，吸氢反应速度缓慢。

Abstract:

The electronic structure and surface energy of Li2MgN2H2 were calculated by the first principle, and then the transition state of molecular H2 adsorption and dissociation on the lowest energy (100) surface was analyzed for re-hydrogenation of Li2MgN2H2. The results show that the Mg-Mg-Li site on the lowest energy (100) surface is the most stable for molecular H2 adsorption and dissociating, where the related energies for these two reactions are about –0.1898 eV and 0.84 eV (81 kJ/mol), respectively. This indicates that the activation energy for re-hydrogenation of Li2MgN2H2 is apparently too high, and it results in the slow reaction rate of hydrogenation.