Synergistic regulation of multi-element doping with octahedral site substitution in Co3O4 for enhanced oxygen evolution reaction.

Electrochemical water splitting represents a critical technology for clean energy conversion. The development of efficient, cost-effective electrocatalysts based on noble-metal-atom doping in non-noble metal oxides holds significant research potential. A series of Ru-, Pd-, Ir-, Ni-, and Mn-doped Co3O4 nanosheet catalysts were synthesized from ZIF-67 via a cooperative doping-coordination strategy. This study presents a synergistic regulation strategy that integrates single-atom metal anchoring with non-stoichiometric, multi-element, high-entropy-like doping to precisely modulate active sites. Comprehensive structural characterizations confirm the successful incorporation of compositionally complex single-atom dopants which preferentially occupy octahedral Co sites in the spinel lattice. This dual-optimization regulatory mechanism significantly enhances the tunability of the Co2+/Co3+ redox couple and improves interfacial charge-transfer efficiency. The resulting catalyst delivers outstanding alkaline OER performance, achieving an overpotential of 269 mV at 10 mA cm-2 and a Tafel slope of 59.1 mV dec-1. DFT calculations also confirm the site-specific occupancy at the octahedral Co sites in the spinel framework. Thermodynamic analysis of the reaction barriers validates the dominance of the AEM pathway during the OER. The synergistic effect of multi-metal doping triggers local charge redistribution, which serves as the fundamental mechanism for reducing the reaction overpotentials.