Silica‐Free Synthesis of Mesoporous Co₃O₄/CoO_xP_y as a Highly Active Oxygen Evolution Reaction Catalyst

Abstract Highly active and stable catalysts towards electrochemical oxygen evolution reaction are crucial for the efficient water splitting and sustainable hydrogen generation. Here we report a novel mesoporous Co₃O₄ with the surface decoration of mixed CoO_xP_y species towards efficient OER catalysis. The material is synthesized from a simple carbon template derived from p‐phenylenediamine bisulfate followed by low temperature phosphorization. Unlike traditional methods, silica intermediates are not involved during synthesis, improving the overall safety and efficiency. The as‐prepared mesoporous Co₃O₄/CoO_xP_y catalyst shows excellent catalytic activity and stability towards oxygen evolution reaction in 1 M KOH. The overpotential is 295 mV at 10 mA cm⁻², superior to that of commercial IrO₂/C catalyst. A small Tafel slope of 70 mV dec⁻¹ and high stability are also observed. The excellent electrochemical performance is attributed to the mesoporous structure, strong electronic interaction, and synergistic effect of the mesoporous Co₃O₄ and CoO_xP_y phases. Other heterogeneous catalysts with similar structures and compositions may also be fabricated following the same design principle.