Tailoring CuNi heteronuclear diatomic catalysts: Precision in structural design for exceptionally selective CO2 photoreduction to ethanol

The photocatalytic reduction of CO2 to ethanol has attracted extensive attention, particularly for intricate C–C coupling. In this study, we propose a synthetic pathway for asymmetric CuNi heteronuclear diatoms (CuNi HDAs) by anchoring single Cu atoms on the Ni sites of (Ni, Zr)-UiO-66-NH2 to enhance C–C coupling. Cu-(Ni,Zr)-UiO-66-NH2 efficiently performs photocatalytic CO2 conversion with a mass-specific activity (selectivity) of 3218 μmol·gCu–1·h–1 (97.3%). Spectroscopic analyses and density functional theory calculations revealed that CuNi HDAs with an asymmetric electronic distribution facilitated the activation of CO2 molecules and lowered the C–C coupling barrier energy, thus promoting the formation of *OCCHO intermediates. This, in turn, led to a significant enhancement of ethanol selectivity. Furthermore, with interfacial Cu–Ni–O bonds as a rapid electron transport channel, CuNi HDAs enrich enough electrons for 12-electron CO2 reduction, thereby enhancing ethanol productivity. This study provides a novel strategy for designing highly selective photocatalysts for CO2 conversion at the atomic scale.