Synergistic Structural Engineering of Hierarchically Porous MnCo2O4@MnS Nanowire Arrays for Oxygen Evolution Catalysis

Abstract

Electrochemical water splitting, a promising route for sustainable hydrogen production, faces significant challenges due to the slow kinetics of the oxygen evolution reaction (OER), a four-electron transfer process. Manganese-based catalysts, with their earth-abundance and tunable electronic structures, hold potential for OER, but their practical application is limited by poor conductivity and low active site density. Herein, we address these issues by surface modification of MnCo 2 O 4 nanowire arrays: oxygen plasma etching enhances surface roughness and oxygen vacancy concentration, followed by controlled MnS nanoparticle deposition to form a core-shell heterostructure (p-MnCo 2 O 4 @MnS). Key parameters include surface structure regulation and dynamic tuning of Mn 2 ⁺/Mn 3 ⁺/Co 2 ⁺/Co 3 ⁺ ratios, which critically influence catalytic performance. Results show plasma etching increases active sites and mitigates Jahn-Teller distortion via interfacial charge redistribution. The composite exhibits an overpotential of 290 mV at 10 mA cm⁻ 2 , which is better than conventional OER catalysts. This work shows synergistic effects of surface modification and structural optimization, advancing high-efficiency sustainable energy technologies.