Operando Insight into the Correlation between the Structure and Composition of CuZn Nanoparticles and their Selectivity for the Electrochemical CO2 Reduction

Bimetallic CuZn catalysts have been recently proposed as alternative in order to achieve selectivity control during the electrochemical reduction of CO2 (CO2RR). However, fundamental understanding of the underlying reaction mechanism and parameters determining the CO2RR performance is still missing. In this study we have employed size-controlled (~5 nm) Cu100-xZnx nanoparticles (NPs) supported on carbon to investigate the correlation between their structure and composition and catalytic performance. By tuning the concentration of Zn, a drastic increase in CH4 selectivity (~70% Faradaic efficiency (F.E.)) could be achieved for Zn contents from 10-50, which was accompanied by a suppression of the H2 production. Samples containing a higher Zn concentration displayed significantly lower CH4 production and an abrupt switch in the selectivity to CO. Lack of metal leaching was observed based on quasi in situ X-ray photoelectron spectroscopy (XPS). Operando X-ray absorption fine structure (XAFS) spectroscopy meas...