Probing the Dynamics of Low-Overpotential CO2‑to-CO Activation on Copper Electrodes with Time-Resolved Raman Spectroscopy
Jim de Ruiter a b
a Inorganic Chemistry and Catalysis, Department of Chemistry, Utrecht University, Daltonlaan, 200, Utrecht, Netherlands
b Institute for Sustainable & Circular Chemistry, Department of Chemistry, Utrecht University
Proceedings of International Conference on Frontiers in Electrocatalytic Transformations (INTERECT22)
València, Spain, 2022 November 21st - 22nd
Organizers: Sara Barja, Nongnuch Artrith and Matthew Mayer
Oral, Jim de Ruiter, presentation 011
Publication date: 11th October 2022

Oxide-derived copper electrodes have displayed a boost in activity and selectivity toward valuable base chemicals in the electrochemical carbon dioxide reduction reaction (CO2RR), but the exact interplay between the dynamic restructuring of copper oxide electrodes and their activity and selectivity is not fully understood. In this contribution, the utilization of time-resolved surface-enhanced Raman spectroscopy (TR-SERS) during CO2 electroreduction will be discussed, which shows the dynamic restructuring of the copper (oxide) electrode surface and the adsorption of reaction intermediates during cyclic voltammetry (CV) and pulsed electrolysis (PE). By coupling the electrochemical data to the spectral features in TR-SERS, we studied the dynamic activation of and reactions on the electrode surface and find that CO2 is already activated to carbon monoxide (CO) during PE (10% Faradaic efficiency, 1% under static applied potential) at low overpotentials (−0.35 VRHE). PE at varying cathodic bias on different timescales revealed that stochastic CO is dominant directly after the cathodic bias onset, whereas no CO intermediates were observed after prolonged application of low overpotentials. An increase in cathodic bias (−0.55 VRHE) resulted in the formation of static adsorbed CO intermediates, while the overall contribution of stochastic CO decreased. The low overpotential CO2-to-CO activation is attributed to a combination of selective Cu(111) facet exposure, partially oxidized surfaces during PE, and the formation of copper-carbonate-hydroxide complex intermediates during the anodic pulses. This work sheds light on the restructuring of oxide-derived copper electrodes and low-overpotential CO formation and highlights the power of the combination of electrochemistry and time-resolved vibrational spectroscopy to elucidate CO2RR mechanisms.



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