Surface effects of functionalized Cu2O-derived Cu(0) for C2+-selective electrochemical CO2 reduction

Abstract

Selective electrochemical carbon dioxide reduction (CO2RR) to multi-carbon (C2+) products is an attractive method to close the carbon cycle as well as to provide a long-term, large-scale energy storage solution. With copper catalysts, since C2+ product formation is in direct competition with the formation of single-carbon products and hydrogen evolution, methods to modulate the product selectivity are highly desirable. In addition, surface charging effects are not commonly considered in CO2RR experiments. Functionalized cuprous oxide-derived copper synthesized via a simple wet chemistry approach was tested in a H-cell set-up and their surface properties were then studied with electrochemical impedance spectroscopy (EIS) and pulsed voltammetry (PV). Selectivity and turnover were observed to improve with imidazole functionalization, with exceptionally high C2+ selectivity and wide C2+-selectivity potential widow with histidine-functionalized catalysts. In addition, strong correlations of parameters describing surface charging effects obtained from EIS and PV highlight its importance in influencing C2+ selectivity. The strong correlation between EIS and PV parameters with C2+ selectivity also suggests the potential of these experiments to be exploited for high-throughput catalyst discovery in the future.