Effect of Humidity on C1, C2 Product Selectivity for CO2 Reduction in a Hybrid Gas/Liquid Electrochemical Reactor

Hybrid gas/liquid-fed electrochemical flow reactors may become attractive alternatives for chemical synthesis once it is understood how catalytic product selectivity may be optimized through the control of gas phase reactants. Using a constant pH basic electrolyte to suppress the hydrogen evolution reaction, we explore how protonation by water vapor added to the flowing CO2 supply affects the CO2 reduction reaction. Although H2 remains the dominant product, supplying dry CO2 gas selectively produces more C2 products than C1. However, adding protons through water vapor changes selectivity toward C1 products, increasing the overall faradaic efficiency of hydrocarbon production while reducing H2 production.