Photoactivation of Cu Centers in Metal–Organic Frameworks for Selective CO₂ Conversion to Ethanol

Catalytic CO2 hydrogenation to ethanol is of practical importance but poses a significant challenge due to the need of forming one C-C bond while keeping one C-O bond intact. CuI centers were recently shown to selectively catalyze CO2-to-ethanol conversion, but these CuI catalytic sites are unstable under reaction conditions. Here we report the use of low-intensity light to generate CuI species in the cavities of a metal-organic framework (MOF) for catalytic CO2 hydrogenation to ethanol. X-ray photoelectron and transient absorption spectros-copies indicate the generation of CuI species via single-electron transfer from photoexcited [Ru(bpy)3]2+-based ligands on the MOF to CuII centers in the cavities and from Cu0 centers to the photoexcited [Ru(bpy)3]2+-based ligands. Upon light activation, this Cu-Ru-MOF hybrid selectively hydrogenates CO2 to EtOH with an activity of 9650 µmol/gCu/h under 2MPa of H2/CO2=3/1 at 150 oC. Low-intensity light thus generates and stabilizes CuI species for sustained EtOH production.