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采用第一性原理方法研究了H2分子在Li2NH(110)晶面的表面吸附。通过研究Li2NH(110)/H2体系的吸附位置、吸附能和电子结构,发现H2分子吸附在Li长桥位时会发生解离,并在Li2NH(110)面形成NH2基,其吸附能为1.178 eV,属于强化学吸附,吸附最稳定。此时,NH2基中的H原子与Li2NH表面的相互作用主要源于H 1s轨道与Li2NH表层N原子的2s,2p轨道重叠杂化的贡献,且N–H键为共价键;另一个H原子与Li2NH表面的相互作用主要是与Li之间的离子键作用;H2分子的解离能垒为1.31 eV,表明在一定热激活条件下H2分子在Li2NH(110)表面发生解离吸附。N顶位吸附时,优化结束后形成NH3,但该吸附方式不稳定,可见Li2NH(110)面与H2反应不易直接生成NH3。
The first-principles method was used to study the adsorption of H2 on the surface of Li2NH (110) crystal. By studying the adsorption sites, adsorption energies and electronic structures of Li2NH (110) / H2 system, it was found that H2 molecules were dissociated when they were adsorbed on the Li long bridge and formed NH2 groups on the Li2NH (110) surface with an adsorption energy of 1.178 eV, belonging to strong chemical adsorption, the most stable adsorption. At this time, the interaction between the H atom in the NH2 group and the Li2NH surface mainly comes from the contribution of the 2s, 2p orbital hybridization of the H 1s orbital to the N atom on the surface of Li2NH, and the N-H bond is a covalent bond. The other H The interaction between Li2NH and Li2NH surface is mainly due to the ionic bond with Li. The dissociation energy barrier of H2 is 1.31 eV, indicating that the H2 molecules are dissociatively adsorbed on the Li2NH (110) surface under certain thermal activation conditions. When N is adsorbed on the top, NH3 is formed after the optimization, but the adsorption mode is unstable. It can be seen that the reaction of Li2NH (110) with H2 is not easy to generate NH3 directly.