Constructing CoNiRuIrMn high-entropy alloy network for boosting electrocatalytic activity toward alkaline water oxidation

Abstract

Anodic oxygen evolution reaction (OER) is crucial for several clean energy storage and conversion processes, like the rechargeable Zn-air battery and electrocatalytic water splitting. However, constructing advanced OER electrocatalysts with exceptional higher activity and stability compared to commercial IrO₂ and RuO₂ remains a significant challenge. Herein, a high-entropy alloy material consisting of five metal elements (Co, Ni, Ru, Ir, and Mn) with a 3D porous network structure is reported to be fabricated through a facile and mild one-pot co-reduction method, enabling its excellent electron/mass transport property and the modulated d-band center to optimize the intermediates adsorption in electrocatalysis. Therefore, the resultant CoNiRuIrMn sample exhibits the overpotential of merely 169 mV to deliver 10 mA cm⁻² in alkaline environment, greatly lower than that of the commercial electrocatalysts (RuO₂ and IrO₂). Significantly, the CoNiRuIrMn catalyst demonstrates an ultrahigh mass activity of 376.2 A g⁻¹, which is 110.6- and 63.8-fold greater than those of IrO₂ and RuO₂ catalysts, respectively. Furthermore, the overall water splitting device assembled with CoNiRuIrMn and Pt/C catalyst presents a much better operation voltage and long-term stability than RuO₂||Pt/C and IrO₂||Pt/C electrolyzers, showcasing its promising potential for efficient hydrogen production.