Interfacial electronic modulation by single-atom metals in nitrogen-doped carbon on Co₃O₄ for acidic oxygen evolution

Non-precious metal-based catalysts for the acidic oxygen evolution reaction (OER) offer great potential due to their continuously improving performance, earth abundance and low cost. However, their catalytic activity and stability remain inadequate for practical applications. Here we implement an interfacial modulation strategy by coating cobalt oxide (e.g., Co₃O₄) nanocrystals with a single-metal-atom–modified, nitrogen-doped carbon (MNC) layer, and further optimize the interface between Co₃O₄ and MCN through single atom metal regulation. Across the series, Co₃O₄/MnNC exhibits a trend-like optimum, delivering overpotentials of 296 and 401 mV at 10 and 100 mA·cm^–2, respectively, and showing excellent durability with only a 36 mV increase after 240 h at 10 mA·cm^–2. Combining X-ray absorption fine structure (XAFS) characterization and density functional theory (DFT) calculations, the Co–N–Mn structure is identified as the active site, while the coating layer suppresses surface structural relaxation of Co₃O₄, thereby improving the structural stability. Moreover, in situ XAFS investigations confirm the formation of a stable Co–N–Mn interfacial structure under operational conditions. These results offer interfacial modulation as an effective route for high-performance, earth-abundant OER catalysts in acidic media.