(726b) Electrochemical Reduction of CO2 on Cu Catalysts in a Diluted Ionic Liquid/Water Mixture

Biddinger, E. - Presenter, City College of New York
Sharifi Golru, S., City University of New York-Graduate Center
The growing atmospheric concentration of CO2, a greenhouse gas, results in global warming and climate change. Electroreduction of CO2 is one of the promising methods to convert waste CO2 to valuable chemicals and fuels. Among the metallic catalysts used in CO2 electroreduction, copper is known to produce hydrocarbons. However, CO2 electroreduction on Cu in traditional aqueous electrolyte suffers from the broad product distribution and low faradaic efficiency 1. Moreover, in aqueous electrolytes, higher overpotentials are required to convert CO2 into the intermediates on metal electrodes1. To overcome these limitations, ionic liquids (ILs) have been proposed as supporting electrolytes due to some unique properties such as the ability to interact with CO22. ILs have been reported to affect the product selectivity and kinetics in CO2 electroreduction on different metals such as silver 2, 3.

In this study, we have investigated the impact of using ionic liquids in CO2 electroreduction on Cu catalysts. CO2 electroreduction experiments were done on Cu flags for 30 mins at different potentials and in a H-type electrochemical cell. The results showed that ionic liquids affect the product selectivity even at very low concentrations. It was observed that by adding just 10 mM 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTF2]) to the 0.1 M KHCO3 electrolyte, the total current density increased by 63% at -1.1 V (vs RHE). Moreover, a 80% increase in FE at -1.1 V (vs RHE) for methane was observed in the ionic liquid/water mixture. We also detected a 50% increase in faradaic efficiency for formate at the lowest examined potential (-0.91 V) when adding the ionic liquid.

1. Hori, Y., Electrochemical CO2 reduction on metal electrodes. In Modern Aspects of Electrochemistry, Vayenas, C. G.; White, R. E.; Gamboa-Aldeco, M. E., Eds. Springer: New York, 2008; Vol. 42, pp 89-189.

2. Mu, T.; Chen, Y., Conversion of CO2 to value-added products mediated by ionic liquids. Green Chemistry 2019.

3. Rosen, B. A.; Salehi-Khojin, A.; Thorson, M. R.; Zhu, W.; Whipple, D. T.; Kenis, P. J. A.; Masel, R. I., Ionic liquid-mediated selective conversion of CO2 to CO at low overpotentials. Science 2011,334(6056), 643-644.