First-Principle Study of H₂ Adsorption on Mg₃N₂(110) Surface

The adsorption of H₂ on two kinds of Mg₃N₂(110) crystal surface is studied by first principles. Adsorption sites, adsorption energy, and the electronic structure of the Mg₃N₂(110)/H₂ systems are calculated separately. It is found that H₂ is mainly adsorbed as chemical adsorption, on these sites the H₂ molecules are dissociated and the H atoms tend to the top of two N, respectively, forming two NH, or the H atoms tend to the same N forming one NH₂. There are also some physical adsorption sites. One of the bridge sites of Mg₃N₂(110) surface is more favorable than the other sites. On this site, H atoms tend to the top of two N, forming two NH. This process belongs to strong chemical adsorption. The interaction between H₂ molecule and Mg₃N₂(110) surface is mainly due to the overlap-hybridization among H 1s, N 2s, and N 2p states, covalent bonds are formed between the N and H atoms.