Interfacial Active Sites in Catalysts for Higher Alcohol Synthesis From CO₂: A Review

Converting CO₂ into higher alcohols is a promising strategy for producing valuable chemicals and fuels while improving carbon utilization. However, achieving selective formation of higher alcohols remains challenging because CO₂ hydrogenation is thermodynamically limited and competes with methanation, the reverse water-gas shift (RWGS), and methanol synthesis. Recent studies suggest that higher-alcohol synthesis is governed not by isolated active sites, but by cooperative interfacial ensembles with complementary catalytic functions. This review examines recent progress in identifying the active sites responsible for higher-alcohol formation in Cu─, Co─, and Mo-based catalysts. Particular attention is given to how interfacial structures, promoter-induced electronic effects, and metal-support interactions influence key steps, including CO₂/CO activation, CH_x formation, CO insertion, and C─C coupling. Cu-based catalysts often rely on Cu─ZnO─Fe_xCᵧ interfaces, while Co-based catalysts are generally linked to Co⁰/Co^δ+ or Co₂C/Co⁰ interfacial motifs, and Mo-based catalysts benefit from adjustable oxidation states and coordination environments that stabilize oxygenate intermediates and promote chain growth. Finally, this review highlights common mechanistic principles, unresolved challenges, and interfacial active-site engineering as a useful strategy for designing more selective catalysts.