First-principles study of H2S adsorption and dissociation on the Ni(111) and Cl-covered Ni(111) surfaces

Abstract

This article is based on density functional theory to calculate and study the adsorption and dissociation of H2S on Ni(111) and Cl-covered Ni(111) surfaces. The calculation results show that H2S is stably adsorbed at the Top site on both surfaces. There is a certain repulsive effect between Cl and H2S, which leads to a decrease in the adsorption strength of H2S. The dissociation energy barriers of the first step for H2S are higher than those of the second step on both surfaces, indicating that the first step of dissociation is the rate-determining step. In the presence of Cl, the energy barrier for the first step of H2S dissociation decreases from 0.27 eV to 0.19 eV, while the energy barrier for the second step of H2S dissociation increases from 0.01 eV to 0.11 eV. This means that the presence of Cl accelerates the first step of H2S dissociation and hinders the second step. The increase energy barrier for the second step of H2S dissociation implies greater difficulty in breaking the SH bond during this step, so the presence of Cl can inhibit the breaking of the SH bond in the second step. Additionally, the decomposition of H2S on both Ni(111) and Cl-covered Ni(111) surfaces is an exothermic process and a spontaneous one.