Regulating the coordination structure of metal single atoms for efficient electrocatalytic CO2 reduction

Electrochemical CO2 reduction reaction (CO2RR) to eliminate the excess CO2 and produce fuels/chemicals under mild conditions provides a sustainable way to maintain the carbon balance and alleviate the energy shortage. However, the low current density, competitive H2 evolution reaction and uncontrollable product distribution are urgent to be solved. Benefiting from the well-defined active centers in single atom catalysts (SACs), the coordination bond, bond length/angle, et al. can be modulated to affect the selectivity/activity towards CO2RR, which relies on electrons transfer, adsorption states and so on. Hence, an in-depth summary about the regulation of coordination structure for CO2RR is significant and pressing. This review concentrates on the manipulation of central atoms, coordination atoms on carbon and other supports in SACs for CO2RR. As a prototype, definitive correlation between structure and XAFS spectra characteristics was properly decoded. Then, the influence of coordination atoms and coordination number on current density, reduction products, reactive path, etc., are highlighted. Finally, prospects such as identification of coordination structure, machine learning, fine adjustment of coordination atoms and control of product distribution were put forward. This Review contributes to provide profound insights for the rational design of coordination structure towards highly efficient and even guided electrocatalytic CO2 reduction.