Effect of Different In₂O₃(111) Surface Terminations on CO₂ Adsorption

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Indium oxide (In2O3)-based catalysts exhibit high activity and selectivity for carbon dioxide (CO2) hydrogenation to methanol.
• The fundamental reasons behind the superior performance of In2O3 remain incompletely understood.

Purpose of the Study:

• To investigate the initial stages of CO2 hydrogenation over In2O3.
• To elucidate the adsorption behavior of CO2 on different In2O3(111) surface terminations.

Main Methods:

• Combined X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations.
• Studied CO2 adsorption on stoichiometric, reduced, and hydroxylated In2O3(111) surfaces.
• Analyzed surface reduction, water dissociation, and CO2 adsorption states.

Main Results:

• Surface reduction of In2O3 leads to the formation of Indium (In) adatoms.
• Water readily dissociates on the In2O3 surface at ambient temperatures.
• CO2 adsorbs as a carbonate species across all examined surface terminations.
• Hydroxyl groups on the surface inhibit CO2 adsorption.

Conclusions:

• The study clarifies the initial CO2 adsorption mechanism on In2O3 surfaces.
• Surface termination significantly influences CO2 interaction, with hydroxyl groups posing a barrier.
• Findings provide insights into optimizing In2O3 catalysts for CO2 hydrogenation.