H₂O₂adsorption and dissociation on various CeO₂(111) surface models: a first-principles study.

Area of Science:

• Materials Science
• Surface Chemistry
• Computational Chemistry

Background:

• Hydrogen peroxide (H2O2) is a key chemical species with diverse applications.
• Understanding H2O2 decomposition mechanisms on metal oxide surfaces like ceria is crucial for catalysis and environmental remediation.
• Ceria (CeO2) is a widely studied material due to its redox properties and catalytic activity.

Purpose of the Study:

• To investigate the initial steps of H2O2 adsorption and decomposition on different ceria (111) surface models.
• To compare the reaction pathways and energy barriers on clean, defective, and hydroxylated ceria surfaces.
• To elucidate the role of surface structure and defects in H2O2 reactivity.

Main Methods:

• Periodic density functional theory (DFT) calculations were employed.
• The hybrid PBE0 functional and atom-centered Gaussian functions were used as basis sets.
• Three ceria (111) surface models were investigated: clean, defective, and hydroxylated.

Main Results:

• On clean ceria, H2O2 decomposition follows a three-step path with low activation barriers (<0.5 eV), forming peroxide and superoxide anions.
• On defective ceria, H2O2 dissociation is energetically favorable, driven by oxygen vacancy healing.
• On hydroxylated ceria, H2O2 adsorbs via H-bonding and dissociates heterolytically, forming new hydroxyl groups.

Conclusions:

• The surface structure of ceria significantly influences H2O2 decomposition pathways and energetics.
• Defects and hydroxylation on ceria can promote or alter H2O2 dissociation mechanisms.
• These findings provide insights into ceria-based catalysis involving H2O2.