Electrochemical carbon dioxide reduction on copper-zinc alloys: ethanol and ethylene selectivity analysis

The electrochemical conversion of CO2 to ethanol and ethylene is an environmentally and economically promising method for addressing global climate change in a carbon-neutral society. Ethanol is desirable because of its high energy density. However, ethanol production is less favored than ethylene production on Cu catalysts. Alloys have gained prominence as a catalyst that enhances ethanol selectivity. In this study, metallic CuZn alloys with different Zn contents (Cu, Cu9Zn1, Cu3Zn1, and Cu2Zn1) were fabricated by co-sputtering Cu and Zn. A maximum ethanol/ethylene ratio of 9.2 was achieved on Cu2Zn1, which is 11 times higher than that of the Cu catalyst. Furthermore, we prepared Cu9Zn1 on polytetrafluoroethylene (PTFE), which achieved an ethanol partial density of approximately 93 mA cm(-2) at -0.76 V vs. RHE. Cu9Zn1/PTFE exhibited stable ethanol production with similar to 25% faradaic efficiency and similar to 11% full-cell energy efficiency of ethanol over a period of 7 h in a membrane electrode assembly system. The remarkable ethanol selectivity of the CuZn catalysts was attributed to the local atomic arrangement, which was supported by density functional theory calculations.