LanthanideDoping and Dual-Site Switching on AmorphousHigh-Entropy Metallene Oxides Boost Acidic Water Oxidation

Abstract

High-entropy oxides (HEOs) are promising electrocatalysts for breaking the Sabatier principle and maximizing their oxygen evolution reaction (OER) efficiency. Herein, the effect of lanthanide doping on RuIr-based HEOs is investigated through theoretical and experimental studies. The optimized amorphous RuIrMnCoGd high-entropy metallene oxides (a-Gd_HEMOs) with moderate intermediate affinity exhibit a small overpotential of 211 mV and an ultralong stability of 700 h at 10 mA cm(-2) in acidic media. Integrated into a proton exchange membrane electrolyzer, they deliver 3.0 A cm(-2) at 1.872 V and maintain stable operation for 300 h at 1.0 A cm(-2). Operando characterizations reveal the changes in electronic configurations and coordination environments of Ru and Ir sites during OER. Theoretical simulations further clarify the adsorbate evolution mechanism and the distinct role of the constituent elements. Specifically, the switching of Ru and activated Ir as primary active sites at low and high potentials, respectively, enhances robustness for oxygen generation.