<p>Oxygen evolution reaction (OER) serves as a crucial anodic process in clean energy systems, its inherently multi-step electron transfer process impedes reaction kinetics, making the development of highly efficient OER catalysts essential for improving energy conversion efficiency. Cobalt-based spinel oxides demonstrate considerable promise as electrocatalysts owing to their highly tunable electronic structures. However, conventional hydrothermal method for synthesizing their precursors is energy-intensive, raises safety issues, and is difficult to scale, thereby underscoring the urgent need for alternative green pathways under mild conditions. In this study, a room-temperature “Mg ion exchange strategy” was adopted to successfully prepare two-dimensional nanosheet MCo₂O₄ spinel precursors (M = Mn, Fe, Co, Ni, Cu, Zn). Electrochemical tests revealed that NiCo₂O₄ exhibited superior OER performance, which was comparable to the hydrothermally synthesized sample NiCo₂O₄-HT. Specifically, it delivered the lowest overpotential (310 mV at 10&#xa0;mA/cm²), the smallest Tafel slope (33.1 mV/dec), the lowest charge transfer resistance (1.8 Ω) and the highest surface area (116.5 m² g^− 1). Comprehensive characterization further revealed that Ni doping induced synergistic enrichment of Co²⁺ and surface oxygen vacancies. This electronic structure modulation promoted charge transfer, which in turn collectively triggered and stabilized the lattice oxygen oxidation mechanism, ultimately leading to the superior OER performance.</p> Graphical Abstract <p></p>