RuO2-Modified High-Entropy Spinel Electrocatalysts for Efficient Alkaline Water-Splitting Reactions

Abstract Developing cost-effective electrocatalysts that can efficiently and stably drive alkaline water-splitting is crucial to the large-scale production of hydrogen. Herein, high- and medium-entropy spinel materials, (CoCuFeMnNi)3O4 (HESOx), (CoCuFeMnNi)3O4PVP (HESOxPVP), and (CoFeMnNi)3O4PVP (MESOxPVP) are prepared via the reverse coprecipitation method and calcination and modified with RuO2 for enhanced performance. The RuO2-modified HESOxPVP exhibits enhanced HER performance, requiring an overpotential of 24.3 mV to achieve 10 mA cm–2. In addition, RuO2/(CoCuFeMnNi)3O4PVP (RuO2/HESOxPVP) shows better OER, reaching 10 mA cm–2 at 322 mV overpotential. Two electrode water-splitting tests with the RuO2/HESOxPVP as both anode and cathode attained 10 mA cm–2 at 1.36 V. It also shows good tolerance toward long-term activity, thereby showing promise as a potential electrocatalyst for large-scale production of hydrogen and oxygen via water-splitting.