CO Binding Energy is an Incomplete Descriptor of Cu‐Based Catalysts for the Electrochemical CO2 Reduction Reaction

CO binding energy has been employed as a descriptor in the catalyst design for the electrochemical CO2 reduction reactions (CO2 RR). The reliability of the descriptor has yet been experimentally verified due to the lack of suitable methods to determine CO binding energies. In this work, we determined the standard CO adsorption enthalpies ( ΔHCO∘${\Delta {H}_{CO}^{^\circ{}}}$ ) of undoped and doped oxide-derived Cu (OD-Cu) samples, and for the first time established the correlation of ΔHCO∘${\Delta {H}_{CO}^{^\circ{}}}$ with the Faradaic efficiencies (FE) for C2+ products. A clear volcano shaped dependence of the FE for C2+ products on ΔHCO∘${\Delta {H}_{CO}^{^\circ{}}}$ is observed on OD-Cu catalysts prepared with the same hydrothermal durations, however, the trend becomes less clear when all catalysts investigated are taken into account. The relative abundance of Cu sites active for the CO2 -to-CO conversion and the further reduction of CO is identified as another key descriptor.