Low‐Coordination Triangular Cu ₃ Motif Steers CO ₂ Photoreduction to Ethanol

Abstract Photoreduction of CO 2 using copper‐based multi‐atom catalysts (MACs) offers a potential approach to achieve value‐added C 2+ products. However, achieving MACs with high metal contents and suppressing the thermodynamically favored competing ethylene production pathway remain challenging, thus leading to unsatisfactory performance in ethanol production. Herein, we developed a “pre‐locking and nanoconfined polymerization” strategy for synthesis of an ultra‐high‐density Cu MAC with low‐coordination triangular Cu 3 motifs (Cu 3 MAC) on polymeric carbon nitride mesoporous nanofibers. The Cu 3 MAC with Cu contents of 36 wt% achieves a high reactivity of 117 µmol g −1 h −1 for ethanol production from CO 2 and H 2 O, with a remarkable selectivity of 98% under simulated sunlight irradiation, representing one of the highest performances in ambient conditions without sacrificial reagents. The superior catalytic efficiency is attributed to the triangular Cu 3 configuration, in which both Cu(I) and Cu(II) coexist, predominantly as Cu(I). Such Cu 3 motifs act as strong alkaline sites that effectively chemisorb and activate CO 2 , extend visible‐light absorption range, while accumulating high‐density electrons and favoring 12‐electron‐transfer products. An accelerated asymmetric C─C coupling with adsorption configuration of the bridge‐adsorbed *CO at paired Cu sites and atop‐adsorbed *CO at adjacent single Cu atom was observed, enabling preferential formation of *CHCHOH intermediates to produce ethanol.