Thiourea Treatment to Boost the Electrochemical Kinetics and Interfacial Stability of MnCo₂O_4.5 Spinel as a Novel Bifunctional Electrocatalyst for Rechargeable Zn–Air Batteries

Developing efficient and cost‐effective bifunctional catalysts is pivotal in advancing Zn–air batteries (ZABs). In this study, a novel multiple‐surface modification strategy is presented for MnCo₂O_4.5 (MCO) spinel electrocatalyst with the pyrolysis of thiourea. The preparation involves a hydrothermal process to obtain MCO, followed by surface modification with varying concentrations of thiourea (10%weight (wt), 30, 50%wt) under nitrogen atmosphere at 300 °C. The 10% wt thiourea‐modified MCO (MCO‐10%T) achieves a half‐wave potential of 0.787 V vs. reversible hydrogen electrode for the oxygen reduction reaction and an overpotential of 450 mV at 10 mA cm⁻² for the oxygen evolution reaction, rivaling the benchmark Pt/C‐RuO₂ catalyst. This enhanced performance arises from the synergistic effects of sulfur doping, carbon coating, and the hierarchical porous structure introduced by thiourea. These features collectively improve electrical conductivity, increase active site availability, and facilitate charge transfer. When employed as an air cathode catalyst for aqueous ZABs, MCO‐10%T demonstrates a high specific capacity of 800 mAh g⁻¹, a power density of 154 mW cm⁻², and outstanding charge–discharge cycling stability. This study offers important guidance for designing bifunctional catalysts with enhanced activity and stability, leveraging surface reconstruction strategies tailored for spinel materials.