Reaction Environment Engineering for Selective C ₃₊ Formation in CO ₂ Electroreduction: Progress and Perspectives

Electrocatalytic CO 2 reduction (ECRR) offers a sustainable way to produce high‐value chemicals. While C 1 and C 2 electrosynthesis have achieved notable success, ECRR‐to‐C 3+ conversion remains limited by two key challenges: low overall C 3+ selectivity and poor selectivity for specific C 3+ products. To address these issues, this review summarizes three main formation mechanisms: *CO–*CO–*CO coupling, *CO 2 –*OCHCH 2 coupling (*CO 2 insertion), and *CO–*OCHCH 2 coupling (*CO insertion). We employ thermodynamic analysis on Cu(100) to build a comprehensive reaction network. This practice identifies key branching points and the competition between hydrocarbon and oxygenate pathways. Building on these insights, we highlight a couple of new reaction environment engineering strategies, which include catalyst architecture and electrolyte interface engineering. This integrated approach holds promise for simultaneously promoting C–C couplings and tuning post‐coupling selectivity. Finally, we propose challenges and perspectives for further development of ECRR‐to‐C 3+ conversion, aiming to guide future research in this field.