Beyond C₁ Products: How Single-Atom Catalysts Contribute to Solar-Driven CO₂ Reduction into C₂₊ Hydrocarbons

Single-atom catalysts (SACs) have demonstrated their potential in photocatalytic CO₂ reduction due to their fascinating properties and well-defined structure for forecasting the mechanism. Although remarkable progress has been achieved in enhancing SAC activity, the selective formation of C₂₊ hydrocarbons with higher energy densities remains a significant challenge, primarily due to the inherent limitations of isolated single-active sites in simultaneously enabling CO₂ adsorption, activation, and C─C coupling. Therefore, in this review, recent advances in SAC-based strategies for promoting C₂₊ hydrocarbons production are summarized, with a particular focus on dual single-atom catalysts and hybrid SAC systems. The introduction of dual metal sites with tunable electronic structures and charge distributions is discussed can stabilize key intermediates (^*CO, ^*CHO), mitigate electrostatic repulsion, enhance intermediate collision probability, influence intermediate adsorption configurations, and ultimately facilitate C─C coupling. By offering insights into the design principles, mechanistic pathways, and characterization techniques, this review aims to motivate future efforts toward the rational design of highly selective and efficient systems for solar-driven CO₂ reduction into C₂₊ hydrocarbons.