Abstract
The reduction of CO2 to CO from bicarbonate feedstocks offers a pathway to directly use aqueous carbon capture solutions while bypassing energy-intensive gaseous CO2 regeneration. Here, we resolve how alkali cation identity affects bicarbonate electrolysis. Our results show that cation identity does not change the rate of in situ CO2 formation, but strongly affects the rate and selectivity of CO2 reduction to CO. CO selectivity increases across the series Li+, Na+, K+, and Cs+, demonstrating a quantitative relationship between CO product selectivity and cation radius.