Single Atom Catalysts for Electrochemical CO₂ Reduction Reaction: Synthetic Strategies and Mechanistic Insights

Electrocatalytic CO₂ reduction is one of the most promising pathways for addressing environmental and green energy concerns while converting CO₂ into added value chemicals and fuels. For this purpose, single-atom catalysts (SACs) have emerged as highly active and selective classes of materials toward electrochemical CO₂ reduction (CO₂RR) due to their unique electronic properties, exposed active centers, and tunable coordination environment. Herein, a critical assessment of the recent development of SACs for CO₂RR is presented. Rational design and synthetic strategies of SACs have been summarized. The interaction of ligands and modulation of both activity and selectivity with extensive analysis on local atomic structure and different SAC types is discussed. The reaction mechanisms of SACs based CO₂RR and synergistic effect of SACs with nanoparticles and nanoclusters are also highlighted, emphasizing enhanced catalytic performance due to improved charge transfer, optimized binding of intermediates, and improved accessibility of the active site. Finally, the future perspective of SACs based CO₂RR is provided.