Recent progress of M-N-C single atom electrocatalysts for carbon dioxide reduction reaction

M-N-C is a class of single-atom catalysts that consist of isolated metal atoms dispersed on heteroatoms doped carbon, showing remarkable efficiency, stability and selectivity for reducing carbon dioxide to various products. In the early studies, M-N-C catalysts mainly produced CO from CO2 reduction, and only a few types of metals, such as Fe and Ni, were explored well as active sites. However, in recent years, with the advancement of synthesis and coordination environment tuning, M-N-C catalysts have demonstrated a wide range of product selectivity, including C1 products such as methane, formic acid, methanol, and even C2 products such as ethylene and ethanol with Cu-N-C catalysts applied. This review focuses on the function of atoms in the structure of M-N-C catalysts and their recent developments. We analyze how the metal atoms, coordination environments, and supporting carbon materials affect M-N-C catalysts' activity and selectivity for CO2 reduction. This review aims to provide a comprehensive overview and helpful guidance for further research and application of M-N-C catalysts in CO2 reduction.