Nanoarchitectonics of single-atom catalysts for electrochemical CO2 reduction: Promoting C-C bond coupling toward multi-carbon products

Electrochemical reduction of carbon dioxide (CO 2 RR) offers a promising pathway for transforming CO 2 , a major greenhouse gas, into valuable C 2+ products such as ethylene, ethanol, and propanol. Among the various catalytic systems under investigation, single-atom catalysts (SACs) have attracted growing interest due to their maximum atomic efficiency, well-defined active sites, and tunable coordination environments. These unique features offer unique opportunities to stabilize key intermediates and potentially direct reaction pathways toward C C bond coupling, intensifying the production of targeted C 2+ products. However, the isolated nature of single atoms often facilitates the C 1 products, and the C C bond coupling poses intrinsic challenges for SACs. Overcoming this bottleneck requires innovative strategies in catalyst design, such as introducing dual-atom motifs, engineering support interactions, or constructing high-density SACs networks to promote intermediate proximity and facilitate dimerization. This review highlights the recent advances in understanding the mechanisms of CO 2 -to-C 2+ conversion over SACs, discusses the fundamental challenges impeding their performance, and outlines emerging design principles for next-generation SACs capable of delivering both high activity and selectivity toward multi‑carbon products. Advancing SACs for CO 2 RR not only opens new directions in electrocatalysis but also holds significant potential for carbon recycling and sustainable energy development. • Unlocking C C bond coupling in CO 2 electroreduction via tailored single-atom catalysts. • High-density SAC architectures redefine pathways toward multi-carbon fuels and chemicals. • Coordination environment engineering emerges as a key lever for precise C 2+ selectivity. • Operando–theory synergy accelerates the blueprint for next-generation SAC design.