Electronic structure of mixed-valence silver oxide AgO from hybrid density-functional theory

Abstract

Mixed-valence AgO has attracted attention due to its utility in battery technologies. Despite this, a nanoscopic understanding of its electronic structure has been lacking and there has been considerable controversy about the formal oxidation states of silver in the system. In this Rapid Communication we study the electronic structure of AgO using density functional theory: generalized gradient approximation (GGA) and a screened hybrid density functional (HSE). GGA is found to be unable to model the mixed valence of the material, resulting in an (AgO)-O-II symmetric structure. We show conclusively using HSE that the oxidation states of silver in AgO are Ag-I and Ag-III, and not Ag-I and Ag-II with holes on neighboring oxygen ions as had previously been predicted.