Phosphate‐Triggered Interlayer Engineering in Cobalt‐Iron Silicate Hydroxides Enables Efficient and Durable Oxygen Evolution Reaction

ABSTRACT Efficient oxygen evolution catalysis is pivotal to advancing water electrolysis as a scalable route to green hydrogen. For layered transition‐metal hydroxide catalysts, incorporating hetero‐anions is widely employed to boost oxygen evolution reaction (OER) activity, yet the underlying promotion mechanism remains debated. Here, we use cobalt‐iron silicate hydroxides (CFSH) as a flexible and robust layered platform to systematically interrogate anion effects by introducing SO 4 2− and PO 4 3− . Notably, phosphate incorporation induces pronounced structural variations and simultaneously optimizing the electronic structure, thereby markedly accelerating OER kinetics. The phosphate‐modified CFSH delivers a low overpotential of 258 mV at 10 mA cm −2 and retains 98.5% of its activity after 24 h of continuous electrolysis. Density functional theory (DFT) further attributes the performance enhancement to an upshifted Co 3d band center and a balanced adsorption energetics, as reflected by a moderate Δ G O* ‐Δ G HO* . This work establishes a mechanistically informed paradigm for leveraging targeted anion regulation in layered architectures to achieve high‐performance OER electrocatalysis.