Theoretical investigation of adsorption and dissociation behaviors of H2O molecules on the surfaces of Transition-metal doped γ-graphyne

Abstract

The characteristics of adsorption and dissociation of H2O molecules on the surfaces of γ-graphyne doped with transition metal atoms (TM-GY) were explored by the first-principles calculation. Transition metal single-atom could be confined firmly at the center of acetylene ring, and it is difficult to migrate to the adjacent center of benzene ring because of the very high diffusion energy barrier. The positions of doped atoms on the TM-GY surfaces could be used as active sites, and H2O molecules on the Sc/Ti/V/Cr/Mn/Fe-GY surfaces all are a typical chemical adsorption. All possible reaction pathways for H2O molecules dissociation on TM-GY surfaces were evaluated. Adsorbed H2O molecules on TM-GY surfaces are more likely to be dissociated into OH and H along the path1 with a lower reaction energy barrier (less than 1.248 eV). Especially, for V/Cr-GY surface, the dissociation energy barrier is as low as 0.317/0.312 eV, this process is exothermic along with a large amount of energy releasing of about 1.524/1.709 eV. Therefore, stable doped substrate together with the lower dissociation barrier promises that TM-GY may serve as a high efficiency catalyst for H2O dissociation.