Nanoconfinement effects on CuBi3 alloy catalyst for efficient CO2 electroreduction to formic acid

Electrochemical reduction reaction of CO2 (CO2RR) toward chemical and fuel production is a compelling component of the new energy system. The dual-metal site strategy is an effective way to realize efficient CO2 electroreduction into formic acid, however, the limited interfacial area and low activity of traditional dual-metal catalysts result in unsatisfactory CO2 electroreduction performance. Herein, we proposed a co-deposition strategy to prepare designed Cu-Bi alloy (CuBi3) which with unique nanoconfinement effect for the mass transport and enlarge the interfacial active area for CO2RR. As expected, the CuBi3 exhibits excellent electrochemical performance on CO2 reduction to formic acid with Faradaic efficiency (FE) of 98.4% and formic acid partial current density of -21.2 mA cm -2 in 0.1 M KHCO3. Experiment and density functional theory (DFT) calculations suggest that CuBi3 catalyst with regulation of electron state and outstanding adsorption capacity of CO2 provide lattice and spatial confinement environment for active sites. This confinement environment can significantly lower the energy barrier for the formation of *HCOO, which are responsible for the high activity and selectivity toward CO2-to-formic acid conversion.