Engineering O–O formation on dual-atom Fe–Mo catalysts for oxygen electrocatalysis

Abstract

Although single-atom Fe–N–C catalysts exhibit outstanding oxygen reduction reaction (ORR) activity, their stability presents challenges due to the oxidation and destruction of Fe–N_x active sites by Fenton-like reactions, severely restricting their application in energy storage and conversion technologies. Here, we construct a dual-atom oxygen electrocatalyst (FeMo/NC) with FeMoN₇ active sites, which demonstrates excellent bifunctional oxygen electrocatalysis performance. The FeMo/NC-based zinc–air battery (ZAB) can operate continuously for over 200 h without significant activity decay, making it superior to the Fe/NC-based ZAB. In situ X-ray absorption spectroscopy (XAS) and Raman characterizations reveal the formation of the *Fe–O–O–Mo* intermediate with an oxygen bridge bond, which synergistically enables adsorption or desorption of O₂ through the Fe–Mo dual-atom sites, avoiding the limitations of the linear scaling relationship and thereby accelerating the oxygen electrocatalysis process. Density functional theory calculations reveal that the bridged oxygen adsorption mode on the Fe–Mo dual-atom sites exhibits lower energy barriers compared to that on single Fe/Mo sites, favoring the oxygen electrocatalysis.