Diatomic Nitrogen-Coordinated Metal-Doping Carbon for Oxygen Reduction: A Focus on Structure and Active Site

Abstract

Diatomic nitrogen-coordinated metal-doping carbon (M-NC) electrocatalysts are marked by rearranged electronic structures and modified active sites, which are a hot frontier of oxygen reduction reaction (ORR). However, precisely prefabricating stable structures and revealing catalytic centers of diatomic M-NC are arduous tasks. In this review, a series of synthetic strategies are outlined, including MOFs and coordination carbon precursors. The significance of metal precursors is also clarified based on controlling a well-defined structure. Subsequently, various structural characterization methods to confirm diatomic dispersion and fine structure are elaborated, emphasizing on aberration-corrected electron microscope technique and X-ray absorption spectroscopy (XAFS) analysis. The poisoning experiments and in situ testing techniques with dynamic monitoring to reveal catalytic active center are discussed. Finally, a summary and several reflections in the development of diatomic M-NC are addressed. This review aims to provide valuable guidance for the preliminary exploration of enhanced diatomic catalysts.