Sb2WO6 modulated Co3O4 with preferential adsorption enables efficient acidic oxygen evolution at low cost

Abstract

Designing low-cost, active and durable acidic oxygen evolution reaction (OER) catalysts for proton exchange membrane water electrolyzers (PEMWEs) remains challenging, primarily due to the difficulty in balancing catalytic performance with acid stability. Here, we present a strategy that enhances the OER activity and stability of earth-abundant cobalt oxide (Co₃O₄) through its integration with antimony tungsten oxide (Sb₂WO₆). The resultant Co₃O₄@Sb₂WO₆ composite exhibits significantly improved intrinsic OER performance and durability in acidic media. Specifically, it achieves a low overpotential of 360 ± 5 mV at 10 mA cm⁻² and demonstrates exceptional stability, retaining operation at 10 mA cm⁻² for over 220 h. Material characterization reveals that Sb₂WO₆ incorporation modifies the Co₃O₄ structure, leading to an elevated average oxidation state of cobalt and generating additional active sites. Operando Raman spectroscopic analysis indicates an increase in catalytically active Co–O species at octahedral sites within Co₃O₄@Sb₂WO₆ during the OER, accelerating the formation of the critical OOH* species. Microkinetic modeling and density functional theory (DFT) calculations corroborate these findings, confirming that the Co₃O₄@Sb₂WO₆ interface effectively lowers the activation energy barrier for the OER. This work not only yields a cost-effective acidic OER electrocatalyst but also provides fundamental insights into cobalt oxide structural engineering for advanced water electrolysis technologies.