Adsorption and dissociation of H2S on Mo2C(001) surface-A first-principle study

The adsorption and decomposition reaction mechanisms of H2S on Mo2C(001) has been systematically studied using self-consistent periodic density functional theory. Results show that the molecular of H2S is adsorbed either on the Mo top site or bridge site. Mulliken population analysis and density of states for H2S/Mo-terminated Mo2C(001) adsorption system are examined to confirm the adsorption mechanism of H2S with the Mo2C(001) surface, which can involve the donation of charge from the “s lone pair electrons” that are LUMO orbitals into the surface and the back donation of electrons from the surface into the HOMO orbital. The optimal pathway for the dissociation of H2S on the Mo2C(001) surface can be H2Stop → SHfcc + Hfcc → Sfcc + Hfcc + Hfcc. The first step is the rate-determining step because it has the smallest rate constant among the possible reactions pathways.