The CO₂ concentration in the atmosphere has increased significantly during the past decades.¹ Electrochemical reduction of CO₂ into various valuable chemical fuels provides a promising solution to extenuate this issue and leads to the renewable development of society.^2-3 However, the unsatisfactory performance of electrocatalysts has prevented the widespread commercial use of this technique. The poor understandings on reaction mechanisms are one of the reasons that hinder the development of more advanced catalysts.

In this study, surface enhanced infrared absorption spectroscopy (SEIRAS) with the attenuated total reflection (ATR) technique was used to probe the reaction mechanisms of CO₂ reduction on Cu thin films deposited on a hemispherical Si prism. Various reaction intermediates (e.g. CO, COH, OCH₃) were detected on CO₂ electrochemical reduction for the first time (Figure 1). The evolution of reaction intermediates during cathodic potential sweep were direct observed and possible reaction pathways on Cu surfaces were proposed.

This work added new insights into the reaction mechanisms of CO₂ electrochemical reduction and would help the rational design of catalyst with a higher activity and selectivity.

References

1. World Meteorological Organization Greenhouse Gas Bulletin, 2014.

2. Hori, Y., in Modern Aspects of Electrochemistry, Springer, New York, 2008.

3. Qiao, J.; Liu, Y.; Hong, F.; Zhang, J. Chemical Society Reviews 2014, 43, 631-675.

Figure 1. Real-time SEIRA spectra recorded during CO₂ electrochemical reduction on a Cu thin film in the cathodic potential sweep in a CO₂-saturated 0.1 M KHCO₃ solution.