(Keynote) Insights into the CO2 Reduction Pathway through the Electrolysis of Aldehydes

Abstract

Investigating the electrochemical reduction of aldehydes to alcohols provides insights into the mechanistic pathways of converting CO2 to alcohols electrochemically. Both acetaldehyde and propionaldehyde were electrochemically reduced on a polycrystalline Cu catalyst to illustrate that it is a viable pathway to ethanol and 1-propanol, respectively, supporting the mechanistic route previously proposed in the literature. 13C and 1H NMR analysis on isotopically labeled acetaldehyde was utilized to trace the reduction process. In an aqueous solution, acetaldehyde is at equilibrium with ethanediol, and propionaldehyde with propanediol. The dissociation of adsorbed ethanediol to acetaldehyde and water was also found to be favorable on both Cu and Au surfaces. Experimental observations were also supported with DFT calculations, indicating a higher-energy reaction intermediate on Au (111) over Cu (100). In summary, the results from this study support previously proposed mechanisms and provide a framework for testing other stable CO2 reaction intermediates to gain insights into the overall CO2 reaction pathway. Figure 1