Advances and challenges in single-site catalysts towards electrochemical CO₂ methanation

Electrochemical CO₂ reduction to a valuable product is a sustainable and economical method towards carbon neutralization. Among the different products of the electrochemical CO₂ reduction reaction (CO₂RR), methane is an excellent energy carrier with a high combustion heat. However, for higher methane product selectivity it is crucial to avoid C-C coupling that leads to multi-carbon products. Thus, single-site catalysts (SSCs) with a single active site are ideal candidates. This review summarizes and discusses the current research progress and future application prospects of electrochemical CO₂ methanation on SSCs. The CO₂ methanation mechanism and primary activity descriptors are discussed in detail with an extensive overview of the coordination structure and design of SSCs, as well as their several in situ characterization methods for tracking the structural changes in SSCs. This review provides insights into the further exploitation of SSCs for selective CO₂ methanation that inspires the rational design of SSCs in electrochemical CO₂ methanation research.