Oxyanion Engineering Renewable Lattice Oxygen Mechanism of CoFe Oxide for Enhanced Water Oxidation

Abstract Lattice oxygen mechanism (LOM) promises CoFe‐based catalysts with superior oxygen evolution reaction (OER) performance in alkaline media. However, the imbalance between rapid consumption and sluggish regeneration of lattice oxygen causes oxygen vacancy accumulation and catalyst structure collapse during OER, resulting in poor activity and stability. To surmount this challenge, an oxyanion‐tailored strategy by adsorbing phosphate ions on CoFe oxide to realize renewable LOM is proposed. The longer Co─O bond with enhanced Co─O hybridization after adsorbing phosphate ion (PO ₄ ³⁻ )stimulates the evolution of lattice oxygen for boosting OER. Meanwhile, the local surficial Co(Fe)OOH formed on CoFe oxide modified by PO ₄ ³⁻ during OER with high adsorption capacity serves as a service station, providing oxygenous intermediates to offset released lattice oxygen of CoFe oxide with satisfied durability. Therefore, the overpotential of CoFe oxide is reduced by 42 mV after adsorbing PO ₄ ³⁻ and the PO ₄ ³⁻ modified CoFe oxide shows an extremely robustness over 300 h with a low attenuation of 0.02 mA h ⁻¹ , outperforming that of pure CoFe oxide (attenuation: 0.26 mA h ⁻¹ ). This work represents a momentous step toward optimizing the catalytic performances of cobalt–iron‐based catalysts by regulating renewable lattice oxygen mechanism.