CO₂ Activation on Ni(111) and Ni(100) Surfaces in the Presence of H₂O: An Ambient-Pressure X‑ray Photoelectron Spectroscopy Study

Nickel-based catalysts play an important role in the chemical transformation of CO2. A fundamental understanding of the interaction between CO2 and Ni surfaces at atomic level is necessary. In this study, the interfacial reactions of CO2 and CO2 + H2O mixture on Ni(111) as well Ni(100) surfaces were investigated using ambient pressure X-ray photoelectron spectroscopy as well as theoretical calculations. The results indicate that the distributions of dissociation products are very different on the Ni(111) and Ni(100) surfaces. Carbonate, CO, and graphitic carbon formed on both Ni(111) and Ni(100) surfaces in the presence of 0.2 Torr CO2. However, more than 90% adsorption species on the Ni(111) surface is the carbonate, whereas the Ni(100) surface is mainly covered by adsorbed CO* and graphitic carbon. The co-adsorption of H2O weakens the influence of structure effect on the interfacial interaction between CO2 and Ni surfaces. Furthermore, the density functional theory calculations suggest that the activation of CO2 on Ni(111) and Ni(100) tends to follow different reaction paths, which are consistent with the experimental results