PNNL

Abstract

First-principles calculations based on density functional theory (DFT) have been performed to study O adsorption in on-surface and subsurface sites. For different coverages, hollow site is found to be the most stable on-surface adsorption site. The subsurface adsorption at the bare Mo surface is found unfavored. The most stable subsurface site, the tetrahedral site, has a higher adsorption energy than on-surface sites. The pre-adsorbed O overlayer reduces the adsorption energy of subsurface O atoms, particularly for the octahedral site at p(2×2) phase. Also, vibrational frequencies, work-function and density of states are presented for O adsorption in on-surface sites.