Reaction Environment Engineering for Selective C₃₊ Formation in CO₂ Electroreduction: Progress and Perspectives

Electrocatalytic CO₂ reduction (ECRR) offers a sustainable way to produce high-value chemicals. While C₁ and C₂ electrosynthesis have achieved notable success, ECRR-to-C₃₊ conversion remains limited by two key challenges: low overall C₃₊ selectivity and poor selectivity for specific C₃₊ products. To address these issues, this review summarizes three main formation mechanisms: *CO-*CO-*CO coupling, *CO₂-*OCHCH₂ coupling (*CO₂ insertion), and *CO-*OCHCH₂ 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-C₃₊ conversion, aiming to guide future research in this field.