Electron transport kinetics via ZnO with ultralow Fe dopant for stable oxygen reduction to H2O2

The two-electron oxygen reduction reaction (2e− ORR) is a promising approach to obtain hydrogen peroxide (H2O2) from oxygen in a friend manner. However, the 4e− ORR being the thermodynamically preferred route to H2O is always competes with the 2e− route. Herein, the ultralow iron was doped into ZnO through a solution combustion synthesis to construct an active and stable catalyst for 2e− ORR. In alkaline conditions, the catalyst exhibits a H2O2 production rate of 3.8 mol gcat−1h−1 and selectivity of more than 95 % with a Faraday efficiency of 88.6 % ± 2.2 %. More importantly, it shows a negligible activity decay with a durability of 500 h, representing the best stability performance among all the metal oxide catalysts. Furthermore, the catalyst exhibits an efficient electrochemical degradation ability of model organic pollutants in alkaline conditions. Experiments and theoretical calculations have demonstrated that the substitution defects generated by trace Fe doping promote the interfacial 2e− ORR transfer rate, leading to a high H2O2 selectivity. This work provides a facile but efficient strategy for the construction of carbon-free metal oxide electrocatalysts for H2O2 production.