Asymmetric active sites originate from high-entropy metal selenides by joule heating to boost electrocatalytic water oxidation

High-entropy materials (HEMs) have garnered tremendous attention for electrocatalytic water oxidation because of their extraordinary properties. Nevertheless, scant attention has been directed toward comprehending the origin of their excellent activity and intricate atomic arrangements. Herein, we demonstrate the synthesis of high-entropy metal selenides (HEMSs) using a rapid joule-heating method, effectively circumventing the immiscibility challenges inherent in combining multiple metal elements. This achievement is collectively verified by a convergence of diverse analytical techniques encompassing quasi in situ X-ray absorption spectroscopy and operando attenuated total reflectance infrared spectroscopy. The HEMS exhibits a low overpotential of 222 mV at 10 mA cm⁻² and extraordinary durability with negligible degradation over a 1,000 h durability test at 10 mA cm⁻² and 500 h at 100 mA cm⁻². Further, our theoretical investigations establish the pronounced mechanism of asymmetric Cu-Co-Ni active units in HEMS by manipulating the interaction of oxygen-containing intermediates, which leads to enhanced OER activity and durability.