A Stable and Low-Cost Metal-Azolate Framework with Cyclic Tricopper Active Sites for Highly Selective CO2 Electroreduction to C2+ Products

The electrochemical reduction of CO2 into multicarbon (C2+) products is important and challenging. Here, we show a stable and low-cost metal-azolate framework, namely, [Cu3(μ3-OH)(μ3-trz)3(OH)2(H2O)4] (Cutrz, Htrz = 1,2,4-triazole), based on the cyclic trinuclear clusters {Cu3(μ3-OH)(trz)3}2+ as the electrocatalyst for highly efficient and selective electroreduction of CO2 to C2+ hydrocarbons (Faradaic efficiencies of C2+ and C2H4 are 80 and 50%, respectively) and a current density of 280 mA cm–2 at the potential of −0.8 V vs reversible hydrogen electrode (RHE), representing remarkable performance reported to date. In situ infrared spectroscopy spectra and density functional theory calculations revealed that the cyclic trinuclear cluster {Cu3(μ3-OH)(μ3-trz)3}2+ acts as the electrochemical active site and that three *CO species can be simultaneously adsorbed on the same side of the active sites with three closely adjacent copper ions, thus giving a higher *CO coverage and higher C–C coupling probability compared to those of the traditional dicopper active sites. More importantly, Cutrz can be easily synthesized at the kilogram scale using an environmentally benign method under ambient conditions, highlighting the promising potential industrial implementation.