Defect-enriched, active, self-supporting, coralline-like, high-entropy spinel oxide (FeNiCoMnCr)3O4 electrodes for high-stability oxygen evolution reaction

Abstract

High-entropy spinel oxides are promising catalysts for the oxygen evolution reaction due to their unique structures and high stability. However, developing defect-enriched, active, self-supporting, high-entropy spinel oxide electrodes is still a challenge. This study is the first to report defect-enriched, self-supporting, coralline-like, high-entropy spinel oxide (FeNiCoMnCr)₃O₄ electrodes (HEO-H500@NF) prepared using a synergistic approach integrating hydrothermal synthesis with hydrogen reduction. The optimized electrode exhibited excellent OER performance with an overpotential of 280 mV at 100 mA cm⁻² and a small Tafel slope of 40.3 mV dec⁻¹, superior to that of most high-entropy oxide catalysts reported so far. Additionally, the electrode maintained a stable overpotential of 280 mV at a current density of 100 mA cm⁻² for 200 hours. Experimental and computational studies showed that the large number of oxygen vacancies on the surface of the HEO-H500@NF electrode was capable of enhancing the adsorption of the OER intermediates at active sites and reducing the energy barrier (formation of *O) of the rate-determining step, thus improving the OER performance. This study provides a new strategy for improving the OER performance of self-supporting, high-entropy oxide electrodes.