Analysis of the influence of impurity gas on the hydrogen storage performance of Ti/2C-BN

Abstract

Ti-modified carbon-doped hexagonal boron nitride (Ti/2C-BN) at a concentration of 25 at% exhibits excellent hydrogen storage performance at room temperature. However, the presence of impurities in large-scale hydrogen production processes such as fossil fuel reforming and biomass gasification may contaminate the surface of hydrogen storage materials. Therefore, it is necessary to study the influence of common impurity gases in hydrogen sources, including O2, CO2, H2S, N2, CO, H2O, CH4, Ar, and He, on the adsorption capacity of H2 after pre-adsorption on the Ti/2C-BN surface, as well as their mechanism of influence. The VASP program package based on density functional theory (DFT) is employed to perform relevant simulation calculations. The results show that the hydrogen storage performance on Ti/2C-BN is not affected by CH4, Ar and He. Although O2, CO2 and CO will occupy the active site of the material, the adsorption energy of H2 is between physical adsorption and chemical adsorption, and its influence can be neglected. The adsorption energy of H2 is increased by H2O. The material is poisoned by H2S and N2, causing its adsorption energy to fall below −0.1 eV.