The Effect of N-Tol-Pyridinium Deposition Time on Copper-Mediated CO2 Reduction

Due to the rise of CO₂ emissions around the world, there is great interest in converting atmospheric CO₂ into useful multi-carbon products such as ethylene and ethanol. This goal can be accomplished by electrocatalytic CO₂ reduction (CO₂R) on copper electrodes. Our team has previously discovered that by using N-substituted aryl pyridinium additives, the selectivity of copper electrodes can be enhanced. As a hydrophobic organic layer is deposited onto the surface of a copper electrode, it suppresses the hydrogen evolution reaction (HER) and the formation of undesired side products such as CO and CH₄, leading to higher selectivity for multi-carbon products. Previously, the additive has been deposited in situ during electrochemical CO₂R and the precise film thickness has yet to be elucidated. This study is focused on analyzing the effect of additive deposition time, which may affect the film thickness, on our system’s CO₂R selectivity profile. In conjunction, we are looking at the effect of deposition time on the electrochemical active surface area (ECSA). The ECSA represents the area on the copper electrode where CO₂R can occur. We suspect that a “sweet spot” deposition time may exist, in which the selectivity profile is optimized, and the resulting film thickness can be probed.