Regulating the coordination structure of metal single atoms for efficient electrocatalytic CO2 reduction
The electrochemical CO2 reduction reaction (CO2RR) to eliminate excess CO2 and produce fuels/chemicals under mild conditions provides a sustainable way to maintain 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, etc. can be modulated to affect the selectivity/activity towards the CO2RR, which relies on electron transfer, adsorption states and so on. Hence, an in-depth summary about the regulation of the coordination structure for the CO2RR is significant and pressing. This review concentrates on the manipulation of central atoms and coordination atoms on carbon and other supports in SACs for the CO2RR. As a prototype, a definitive correlation between the structure and XAFS spectra characteristics was properly decoded. Then, the influence of the coordination atoms and coordination number on the current density, reduction products, reaction path, etc., is highlighted. Finally, prospects such as identification of the coordination structure, machine learning, fine adjustment of the coordination atoms and control of the product distribution were put forward. This Review contributes profound insights for the rational design of the coordination structure towards highly efficient and even guided electrocatalytic CO2 reduction.