Real-Time Observation of Reaction Processes of CO2 on Cu(997) by Ambient-Pressure X-ray Photoelectron Spectroscopy

The reaction of CO2 on the vicinal Cu(997) surface at 340 K under CO2 gas pressure of 0.8 mbar was investigated by ambient pressure X-ray photoelectron spectroscopy. A main reaction product on the surface was identified as carbonate (CO3), based on estimation of the composition ratio of oxygen to carbon. CO3 was produced on the surface through the reaction of CO2 with oxygen formed from CO2 dissociation. The amount of adsorbed CO3 was increased and saturated as time elapsed. After saturation of adsorbed CO3, atomic oxygen appeared on the surface, indicating that CO2 dissociation into CO and O continued to take place. The present study shows the importance of CO3 intermediate in the CO2 chemistry on stepped Cu surfaces.