Enhanced Hydrogen Adsorption on In₂O₃(111) via Oxygen Vacancy Engineering

Area of Science:

• Materials Science
• Surface Chemistry
• Catalysis

Background:

• Indium oxide (In₂O₃) is a promising catalyst for selective hydrogenation reactions.
• The precise mechanism of hydrogen dissociation on In₂O₃ surfaces is not well understood.

Purpose of the Study:

• To elucidate the role of oxygen vacancies in hydrogen interaction with In₂O₃ surfaces.
• To investigate the adsorption and dissociation pathways of hydrogen on In₂O₃.

Main Methods:

• Utilized in situ near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and ultraviolet photoelectron spectroscopy (UPS).
• Employed infrared reflection absorption spectroscopy (IRRAS) and density functional theory (DFT) calculations.
• Studied both oxidized In₂O₃(111) and oxygen-deficient In₂O_3-x (111) surfaces.

Main Results:

• Hydrogen (H₂) dissociates and adsorbs as hydroxyl (OH) groups exclusively on the In₂O_3-x (111) surface.
• Adsorbed hydrogen species act as electron donors, leading to electron accumulation and downward band bending.
• DFT calculations confirm oxygen vacancies are essential for heterolytic H₂ dissociation, stabilizing In-H and OH species.

Conclusions:

• Oxygen vacancies significantly influence hydrogen dissociation and adsorption on In₂O₃.
• The findings provide critical insights into the catalytic mechanisms of indium oxide in hydrogenation and redox reactions.