Folding-fan-like Mn–Co3O4@Mo–Co3O4 core-shell heterostructure with high-valence dual doping for efficient seawater electrolysis

Designing affordable electrocatalysts that accelerate the oxygen evolution reaction and resist chloride corrosion is key for practical seawater electrolysis. A fan-like Mn–Co 3 O 4 @Mo–Co 3 O 4 core–shell heterostructure was synthesized, where vertically aligned Mn-doped Co 3 O 4 nanowires serve as structural ribs and conformal Mo-doped Co 3 O 4 nanosheets form the fan surface. Dual Mn/Mo doping creates oxygen vacancies and modulates the metal–oxygen electronic structure, boosting intermediate adsorption and OER kinetics, while the nanosheet–nanowire framework maximizes active sites and facilitates charge and mass transport. As a result, the catalyst delivers an overpotential of 220 mV at 50 mA cm −2 in 1 M KOH, outperforming other reference samples. In alkaline seawater, it maintains overpotentials of 252 and 289 mV at 50 and 100 mA cm −2 and exhibits negligible degradation over 120 h with nearly 100% Faradaic efficiency. These results demonstrate that synergistic electronic tuning and nano-architectural design enable robust electrocatalysts for efficient seawater electrolysis.