Covalency‐Controlled Titanate Pyrochlore Nanoparticles with Enhanced Oxygen Electrocatalytic Activity for Zinc–Air Batteries

Pure‐phase titanate pyrochlores, BIi 2 Ti 2 O 7 (BTO) and Y 2 Ti 2 O 7 (YTO), are synthesized via an optimized sol–gel method that effectively suppresses secondary phase formation and produces uniform nanoparticle morphologies. Comprehensive structural and interfacial characterizations reveal that YTO exhibits stronger TiO covalent bonding and a lower density of oxygen vacancies compared to BTO, despite both adopting the same A 2 B 2 O 7 pyrochlore framework. Electrochemical evaluations in alkaline media demonstrate that this enhanced covalency in YTO promotes improved charge–transfer kinetics and stabilizes key oxygenated intermediates, resulting in superior bifunctional electrocatalytic activity. Notably, YTO achieves a low oxygen evolution reaction overpotential of 350 mV at 10 mA cm −2 and delivers durable round‐trip performance in rechargeable zinc–air flow batteries, surpassing the conventional Pt/C + RuO 2 benchmark. These results underscore that Ti‐centered active sites and strong interfacial covalent networks—rather than oxygen‐vacancy density alone—play a decisive role in governing oxygen electrocatalysis. Given their structural tunability, cost‐effectiveness, and excellent interfacial stability, titanate pyrochlores represent promising alternatives to noble‐metal‐based catalysts for next‐generation metal–air batteries and other surface‐sensitive energy applications.