The effect of metal matrix M (M = Co, Ni, Cu) on the water dissociation performance of oxophilic Cr from density functional theory

Abstract

In this paper, the water dissociation abilities of transition metals Cr, Co, Ni, Cu, and surface Cr incorporated into Co, Ni, and Cu matrix were estimated using density functional theory. The calculations indicate that the transition metal matrix can markedly affect the ability of surface Cr to promote H₂O dissociation. The barriers of the H₂O dissociation step on Cr, Co, Ni, and Cu increase in sequence. After introducing Cr into a transition metal matrix, the H₂O dissociation ability of Cr reduces. Compared with pure metals, doping the Co surface with Cr is less favorable for H₂O dissociation and introducing Cr onto Ni and Cu surfaces can accelerate the H₂O dissociation reaction and Cr–Ni has stronger H₂O dissociation ability than Cr–Cu. The electron distribution calculations show that the electron deviation levels from Cr to the metal matrix are a key factor in affecting the H₂O dissociation ability of surface Cr, and strong electron deviation is advantageous. The adsorption calculations reveal that the OH-binding energy of catalyst cannot relate to its H₂O dissociation ability and follows a rough volcano relationship with its alkaline HER performance.