Rational design, application and dynamic evolution of Cu–N–C single-atom catalysts

Benefiting from the unique electronic and structural characteristics, transition metal and nitrogen co-doped carbon-based (M–N–C) nanomaterials are considered to be one of the most promising catalysts. The combination of uniformly dispersed Cu sites and N-doped carbon materials has enabled Cu–N–C SACs to show outstanding performances in many catalytic fields. However, the adjustment of their coordination environment, the influence of carrier materials and their dynamic evolution in the catalytic process still remain unclear, which limits the application of Cu–N–C SACs. Thus, it is of great significance and urgent to deeply understand the reaction mechanism of Cu–N–C SACs in different catalytic fields. This review focuses on the preparation strategy, regulation mechanism of the coordination environment, catalytic performance and dynamic evolution process of Cu–N–C SACs. Combined with a series of in situ/operando characterization methods, the changes in their coordination and structure in the catalytic process is highlighted. Finally, the prospects of active machine learning, coordination structure identification and determination of real active sites are presented. This review aims to provide a reference for the rational design of Cu–N–C SACs and the exploration of their catalytic mechanism.