Modulating coordination environment of Fe single atoms for high-efficiency all-pH-tolerated H2O2 electrochemical production

Designing atomically dispersed non-precious metal catalysts for 2e− oxygen reduction reaction (ORR) is an appealing strategy to harness O2-to-H2O2 chemistry. Nevertheless, prevailing M–N–C single-atom catalysts (SACs) might still not satisfy the directional regulation of ORR selectivity, hence fail to uphold scalable H2O2 electrosynthesis with a high yield. Herein, we report the precise synthesis of (O,N)-coordinated Fe SAC (FeN2O2) and relating investigation of its performance in H2O2 production over a wide pH range, in comparison with the FeN4 counterpart. Density functional theory simulations reveal that the coordination chemistry engineering has a profound influence on the strength of the oxygen intermediate adsorption. The electron delocalization of M–O configuration readily lowers the d-band center of the Fe metal, which is beneficial to weakening the intermediate adsorption capability and promoting the 2e− ORR process. The thus-derived FeN2O2 exhibits impressive selectivity in a wide pH range, particularly reaching 95% in alkaline conditions. Furthermore, our designed gas-diffusion electrode enables a favorable H2O2 yield (300 mmol L–1) at a current density of 60 mA cm–2 for 50 h. This work is anticipated to inspire the rational design of definitive SAC architecture for practically feasible electrochemical production of H2O2 toward environmental remediation.