Engineering Hierarchical MCo2O4/NF Nanowire Networks via Cation Substitution for High-Performance Oxygen Evolution Reaction

Abstract

Spinel Co3O4 has emerged as a highly promising electrocatalyst for the oxygen evolution reaction (OER), yet enhancing the intrinsic activity of its octahedral Co3+ sites remains challenging. Herein, we strategically tune the polarization degree of Co3+-O bond in Co3O4 octahedron through cation substitution to synthesize MCo2O4/NF (M = Ni, Zn, Mn) nanowire catalysts with hierarchical three-dimensional architecture. The compositionally optimized MCo2O4/NF catalysts synergistically integrate one-dimensional nanowire morphology with binary compositional modulation, resulting in elevated densities of catalytically active Co3+ sites and oxygen vacancies compared to pristine Co3O4/NF. Among the series, NiCo2O4/NF exhibits superior OER performance with an overpotential of only 277 mV at 10 mA cm-2 and a Tafel slope of 91 mV dec-1, significantly outperforming Co3O4/NF. The catalyst maintains excellent stability and durability over 24 h of continuous operation in alkaline electrolyte. This work demonstrates the efficacy of combining cationic substitution with nanowire architectural engineering to enhance Co3O4 catalytic activity and provides insights for designing high-performance cobalt-based spinel oxide electrocatalysts.