Electrocatalytic CO₂ Reduction to Chemicals and Fuels: From Single-Atom to Dual-Atom

In recent years, single-atom catalysts (SACs) have emerged as a prominent research focus in electrochemical CO₂ reduction reactions (CO₂RR), owing to their exceptional atomic utilization efficiency and superior catalytic performance. Nevertheless, their practical implementation may be constrained by inherently low metal loading and the presence of linear relationships imposed by their structurally simplistic active sites. Atomic-level engineering of active sites represents a transformative strategy to overcome the intrinsic limitations of SACs. Building upon the foundation of SACs, dual-atom catalysts (DACs) exhibit enhanced metal loading capacity and more sophisticated active site configurations, leading to superior catalytic performance and broader opportunities in electrocatalytic applications. This review first explains the possible reaction pathways for product generation via CO₂RR, including the underlying mechanisms, key intermediates, and strategies to optimize these pathways. Subsequently, a comprehensive overview of synthetic strategies and precise atomic-level characterization of atomic-scale catalysts is presented. SACs and DACs are systematically categorized according to their active site architectures and electronic configurations. The significant advantages of DACs over SACs in increasing the metal atom loading, promoting the adsorption and activation of CO₂ molecules, regulating intermediates, and promoting C-C coupling are compared. Finally, the prevailing challenges and future development prospects of DACs are summarized.