Modulating Electronic\nCorrelations in Ruthenium Oxides\nfor Highly Efficient Oxygen Evolution Reaction

Elucidating the electronic factors dominating the adsorption\nproperties\nof transition-metal oxides is essential to construct highly efficient\noxygen-evolving catalysts for hydrogen production by water splitting\nbut remains a great challenge. Electron correlation from on-site Coulomb\nrepulsion (<i>U</i>) among d-electrons is generally believed\nto significantly affect the electronic structure of these materials;\nhowever, it has long been neglected in studying their adsorption properties.\nHere, by choosing ruthenium oxide as a model system, we demonstrate\nthe role of electron correlation on the electrocatalytic activity\ntoward oxygen evolution reaction (OER). Our density functional theory\nplus U calculations on rutile RuO<sub>2</sub> reveal that the electron\ncorrelation can tune the adsorption energies for oxygenated intermediate\nand optimize them after the metallic oxide being a Mott insulator\nupon increasing <i>U</i>. By regulating the RuO<sub>6</sub> octahedral network, we constructed and synthesized a series of strongly\ncorrelated ruthenium oxides, where the Mott insulating ones indeed\nexhibit a superior OER performance to the metallic RuO<sub>2</sub>. Our work builds a bridge between the electrochemistry and Mott\nphysics for transition-metal oxides, opening a new avenue for designing\nadvanced catalysts.