Electrochemical reduction of CO₂ to C₃₊ products, including alcohols and hydrocarbons, remains challenging. However, extensive research efforts have been devoted to the conversion of CO₂ to these valuable products. This review highlights recent mechanistic understanding of how carbon chain grows in these multiple proton-coupled electron transfer steps.

Electrochemical reduction of carbon dioxide to value-added chemical feedstocks and fuels presents a promising strategy for carbon utilization and storage. Although advancements in enhancing the selectivity for C₁ and C₂ products have been witnessed, the research progress for efficient production of C₃₊ molecules remains slow. Moreover, the mechanism underlying carbon chain growth is still ambiguous. In this review, the recent developments in understanding how C–C coupling proceeds in the pathway toward C₃₊ molecules are mainly focused on. A few examples which reported the formation of C₃–C₆ molecules in electroreduction of carbon dioxide are first elaborated. Then, the production of 1-propanol, 2-propanol, 1-butanol, allyl alcohol, and propylene, with particular attention to the mechanism of carbon chain growth, is consecutively discussed. Moreover, alternatives for synthesizing valuable C₃₊ molecules from carbon dioxide, including tandem electrolyzer and electro–bio hybrid systems, are explored. The review is concluded with remarks on current challenges as well as perspectives on future research possibilities in electroreduction of carbon dioxide to C₃₊ chemicals and fuels.