Designing catalysts and interfacial environments for CO2 reduction toward C3+ products.

The electrochemical CO2 reduction reaction (CO2RR) yielding C3+ products offers an attractive route for producing valuable long-chain fuels and chemicals. However, direct CO2-to-C3+ conversion remains substantially challenging because it requires concerted control over complex processes involving CO2 activation, types and accumulation of C1/C2 intermediates, multiple C-C couplings, and product desorption. Increasing reports demonstrate that catalysts and interfacial environments collectively govern CO2 reduction pathways, whereas general design principles and strategies are lacking. This review summarizes recent progress in C3+ electrosynthesis from the perspective of catalyst design and interfacial environment engineering. The fundamentals underlying the formation of various C3+ products are first discussed, followed by outlining catalyst design principles based on facets, alloying, atomic-site engineering, defects, surface ligand modification, and morphology control, emphasizing how these strategies regulate the adsorption strength of intermediates and their transport and residence. Furthermore, the effects of electrolyte pH, cations, anions, and porous modification layers on reshaping the local interfacial environment and CO2RR pathways by controlling proton availability, solvation structure, interfacial electric fields, and hydrophobicity are analyzed. Then, state-of-the-art advances in CO2-to-C3+ conversion over representative Cu-based and non-Cu-based (Ni, Mo, Co, and Fe) catalysts are critically assessed, with particular focus placed on the structure-performance relationship to reveal catalytic mechanisms. Lastly, challenges and future research directions are suggested to promote renewable energy-powered CO2-to-C3+ transformation.