Modulating Electronic Correlations in Ruthenium Oxides for Highly Efficient Oxygen Evolution Reaction

Elucidating the electronic factors dominating the adsorption properties of transition-metal oxides is essential to construct highly efficient oxygen-evolving catalysts for hydrogen production by water splitting but remains a great challenge. Electron correlation from on-site Coulomb repulsion (U) among d-electrons is generally believed to significantly affect the electronic structure of these materials; however, it has long been neglected in studying their adsorption properties. Here, by choosing ruthenium oxide as a model system, we demonstrate the role of electron correlation on the electrocatalytic activity toward oxygen evolution reaction (OER). Our density functional theory plus U calculations on rutile RuO2 reveal that the electron correlation can tune the adsorption energies for oxygenated intermediate and optimize them after the metallic oxide being a Mott insulator upon increasing U. By regulating the RuO6 octahedral network, we constructed and synthesized a series of strongly correlated ruthenium oxides, where the Mott insulating ones indeed exhibit a superior OER performance to the metallic RuO2. Our work builds a bridge between the electrochemistry and Mott physics for transition-metal oxides, opening a new avenue for designing advanced catalysts.