Electrochemical Reduction of Amine-Captured CO2 in Aqueous Solutions

Technologies that can capture CO2 and enable conversion into value-adding chemicals and fuels or stable minerals for sequestration are vital for transitioning towards net zero or even negative greenhouse gas emissions. Conventional approaches for electrochemically converting CO2 have utilized a decoupled approach of first capturing and concentrating CO2, and then using the concentrated CO2 as a feedstock for conventional electrochemical processes. Direct electrochemical reduction of amine-captured CO2 1,2 can potentially offer advantages by removing the need to thermally regenerate the amine capture solution, which can be energy intensive and typically uses thermal energy from nonrenewable sources. In this talk, we share our recent work on the electrochemical reduction of amine-captured CO2 to value-adding products like CO and stable minerals like carbonates. We discuss the influence of the capture environment on the resulting capture solution chemistry, and how to alter the capture solution speciation through electrolyte design. We further consider the detailed CO2 reduction mechanisms in these amine-containing solutions and provide design strategies for increasing the Faradaic efficiency of CO2 reduction vs. the competitive hydrogen evolution reaction (HER), as well as decreasing the overpotential of CO2 reduction. References: (1) Chen, L.; Li, F.; Zhang, Y.; Bentley, C. L.; Horne, M.; Bond, A. M.; Zhang, J. Electrochemical Reduction of Carbon Dioxide in a Monoethanolamine Capture Medium. ChemSusChem 2017, 10 (20), 4109–4118. (2) Lee, G.; Li, Y. C.; Kim, J.-Y.; Peng, T.; Nam, D.-H.; Sedighian Rasouli, A.; Li, F.; Luo, M.; Ip, A. H.; Joo, Y.-C.; Sargent, E. H. Electrochemical Upgrade of CO2 from Amine Capture Solution. Nat. Energy 2021, 6 (1), 46–53.