First-Principles Study Of Hydrogen Adsorption On Beryllium (0001) And Beryllium Oxide (0001) Surface

Beryllium are widely used in nuclear industries for low density, high melting point, neutron multiplication ability, good thermal conductivity, no chemical reaction with hydrogen and low hydrogen solubility. In this work, the first-principles calculations based on density functional theory is employed to investigate the adsorption of oxygen and hydrogen on Be(0001) and BeO(0001) surface with different coverage. In addition, the methane adsorption and dissociation on Be(0001) surface is discussed by the nudged elastic band method. The main conclusions can be summarized as follows:1. The most stable configurations of oxygen atom on Be(0001) surface and mechanical properties are calculated. The results show that beryllium surface is oxidized to form BeO due to the strong interaction between the oxygen and the beryllium atoms. According to the mechanical stabilitycriteria, all the systems of different coverages are stable configurations at ground state. Increasing of oxygen coverage, the fracture resistance abilities and stretch resistance ability of oxygen adsorption on the Be(0001) surface increased.2. The most stable configurations of hydrogen atoms on Be(0001) and BeO(0001) surface and the mechanical properties are investigated. The calculations of adsorption energies indicate that the configurations of hydrogen adsorption are more stable on the BeO(001) surface than on Be(0001) surface. Alternatively, the calculated results of mechanical properties indicate that all hydrogen adsorption systems are stable configurations at ground state. With the increase of hydrogen coverage, the shear resistance and stretching ability of hydrogen adsorption reducded and the fracture abilities of the systems of hydrogen atoms adsorbed on the BeO(0001) surface increased. Compared with that on Be(0001) surface, the shear resistance and stretching ability of hydrogen adsorption on BeO(0001) surfaceis stronger, higher stiffness and plastic better.3. The methane adsorption and dissociation on Be(0001) surface are discussed using NEB method. The most stable structures of H and CHx(x=0-4) on Be(0001) surface are determined. In addition, the dissociation process of CH4 was investigated.The activation energy and transition state configuration of the methane dehydrogenation reaction were calculated. The results indicate that the dissociation of CH4 on Be(0001) surface is exothermic and the main dissociation product is carbon.