Insight into the electrochemical reduction of CO2 on gold via surface-enhanced Raman spectroscopy and N-containing additives

Abstract

Due to increasing levels of greenhouse gases in the atmosphere, increased attention has been given to minimizing their emissions and reducing current levels. Primarily focusing on CO2, routes towards reducing atmospheric levels include capture, sequestration, and conversion. For CO2 conversion, Au electrocatalysts have demonstrated high CO2 reduction activity to CO which can then be further converted to various synfuels or commodity chemicals. In this work, we further probe Au electrocatalysts by utilizing a Ag-based model, using N-containing additives, such as pyrazole and benzotriazole, and surface-enhanced Raman spectroscopy. Surface-enhanced Raman spectroscopy (SERS) reveals that only in the presence of N-containing additives is a stronger CO band seen. These additives do not affect the CO2 reduction mechanism of Au, as found by Tafel and product distribution analysis. We also demonstrate enhancement of the CO2 reduction rate on Au by utilizing a known CO2 scavenger, ethanolamine, adsorbed on the Au surface. This result suggests that improving CO2 reduction should focus on the reactant side of the Sabatier plot.