Fe-based dual-atom catalysts for the oxygen reduction reaction

Abstract

The oxygen reduction reaction (ORR) is widely employed at the cathode of next-generation energy devices such as fuel cells and metal–air batteries to accommodate electrons produced by anode reactions. The development of highly efficient and durable electrocatalysts for the ORR has been constrained by the involvement of multiple oxygen-containing intermediates and their scaling relations. Recently, dual-atom catalysts (DACs) supported on carbon materials have been intensively studied as ORR electrocatalysts due to their potential to precisely tune the adsorption/reactive performance of each metal site. In particular, Fe-based DACs exhibit outstanding ORR activities, holding great promise as substitutes for state-of-the-art Pt-based catalysts. However, the adjustment of the microenvironment of metal sites, loading density, scaling relation limitation, and excessively strong adsorption energy pose limitations on the practical applications of Fe-based DACs. To promote studies of Fe-based DACs, we summarize the current research status in this review by focusing on (1) the fundamental of the ORR and effects of Fe-based DACs, (2) common synthesis strategies of Fe-based DACs, and (3) ORR performance evaluations of Fe-based DACs. Additionally, this review provides our viewpoint on future directions and possible strategies to design catalysts for further optimization of the ORR.