Interfacial hydrogen bonds induced by porous FeCr bimetallic atomic sites for efficient oxygen reduction reaction.

Abstract

Interfacial hydrogen bonds are pivotal in enhancing proton activity and accelerating the kinetics of proton-coupled electron transfer during electrocatalytic oxygen reduction reaction (ORR). Here we propose a novel FeCr bimetallic atomic sites catalyst supported on a honeycomb-like porous carbon layer, designed to optimize the microenvironment for efficient electrocatalytic ORR through the induction of interfacial hydrogen bonds. Characterizations, including X-ray absorption spectroscopy and in situ infrared spectroscopy, disclose the rearrangement of delocalized electrons due to the formation of FeCr sites, which facilitates the dissociation of interfacial water molecules and the subsequent formation of hydrogen bonds. This process significantly accelerates the proton-coupled electron transfer process and enhances the ORR reaction kinetics. As a result, the catalyst FeCrNC achieves a remarkable half-wave potential of 0.92 V and exhibits superior four-electron selectivity in 0.1 M KOH solution. Moreover, the zinc-air battery assembled by FeCrNC demonstrates a high power density of 207 mW cm^-2 and negligible degradation over 240 h at a current density of 10 mA cm^-2.