Surface Engineering Modulation Unlocks Durable Acidic Oxygen Evolution Catalysis in Co ₃ O ₄

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.