Abstract: The electrochemical CO₂ reduction reaction (CO₂RR) is a method to convert CO₂ into chemicals and fuels by using electricity generated from renewable sources. CO is an intermediate in this process, which can be split into two steps. The first is the conversion of CO₂ to CO, while the second is the further reduction of CO into hydrocarbons and oxygenates.

This second step, which is known as the electrochemical CO reduction reaction (CORR), occurs on the surface of copper catalysts under alkaline conditions. The CORR produces C₁ products such as methane and more commercially favorable C₂₊ products such as ethylene, ethanol, and n-propanol but suffers from competition from the undesirable hydrogen evolution reaction.

The goal of this work is to elucidate selectivity trends in the CO₂RR with a view to developing design principles for optimizing the production of C₂₊ products. Effects such as reactant mass transport, copper catalyst preparation method, and the nature of the electrolyte cation can all impact the reaction selectivity. However, these effects are not well understood and remain a topic of discussion in recent literature.

In this work, we employ in situ attenuated total reflection surface enhanced infrared absorption spectroscopy coupled with reactivity studies to probe the electrochemical interface and obtain mechanistic insights into the CO₂ RR pathway.