Surface Engineering Modulation Unlocks Durable Acidic Oxygen Evolution Catalysis in Co3O4

Abstract Cobalt oxides are promising alternatives to noble metal catalysts for the acidic oxygen evolution reaction (OER). However, while polarizing Co3O4 to high anodic potentials can accelerate OER, the pH-dependent redox potential of cobalt often leads to rapid structural degradation from cobalt cation dissolution. In this study, we significantly enhanced the OER activity and durability of Co3O4 using a surface engineering strategy to create Co2MnOx@Co3O4 heterostructures. The addition of Co2MnOx not only reduced the overpotential at 50 mA cm−2 from 556 mV to 427 mV but also significantly improved stability, extending the catalyst's lifetime in 0.5 M H2SO4 from ∼12 h to over 370 h—a 30-fold increase. Our detailed mechanistic investigation reveals that the heterostructure interface creates a powerful electronic modulation within the Co3O4 lattice. This electronic restructuring shifts the cobalt d-band center toward the Fermi level, which enables the formation of corrosion-resistant, high-valent active species at a lower potential. This modification not only boosts intrinsic OER activity by optimizing intermediate adsorption but also fundamentally fortifies the catalyst's structure against degradation. Our work highlights a powerful and facile surface engineering strategy to create cost-effective, earth-abundant catalysts with high durability for acidic OER.