Cationic Copper Species Stabilized by Zinc during the Electrocatalytic Reduction of CO2 Revealed by In Situ X-Ray Spectroscopy

Advanced in situ X-ray absorption spectroscopy characterization ofelectrochemically co-electrodeposited bi-element copper alloy electrodesshows that zinc yields the formation of a stable cationic Cu species during theelectroreduction of CO2 at high cathodic polarization. In contrast, theformation/stabilization of cationic Cu species in copper oxides, or doping Cuwith another element, like Ni, is not possible. It is found that the pure andmixed Cu:Zn electrodes behave similarly in term of electrocatalytic selectivityto multi-carbon products. At higher Zn concentrations the electrode behaveslike the pure Zn catalyst, which indicates that the Cu cationic species do nothave a significant influence on the selectivity to multi-carbon products. It isfound that in the non-monotonically distribution of products is dominated interm of surface energy in which copper prefers the surface. Otherwise, thiswork highlights the importance of in situ characterization to uncover themechanisms mediating the catalytic reactions in contrast to ex situ or postmortem analysis, which can be a source of misinterpretation.