Thermodynamic, electronic and structural properties of Cu/CeO2 surfaces and interfaces from first-principles DFT+U calculations
Abstract
Thermodynamic, structural and electronic properties of Cu/CeO2 systems are calculated by means of DFT+U method. We focus on Cu atom supported by stoichiometric and reduced CeO2(111) surface, dispersed as substitutional solid solution at the same surface, and Cu(111)/CeO2(111) interface.
Charge reorganization at metal/oxide contact is predicted for supported Cu particles, leading to Cu oxidation, CeO2 reduction, and interfacial Ce3+ ions. Thermodynamics predict that Cu adatom on stoichiometric surface is more stable than on O vacancy at all temperatures and pressures relevant for catalytic applications.
Supported Cu nanoparticles thus do not nucleate at surface O vacancies, at variance with other metal/ceria systems. In oxidizing conditions, solid solutions are more stable and promote an easy and reversible O release without reducing Ce ions.
The study of CeO2/Cu interface predicts full reduction of the interfacial CeO2 trilayer. Cu nanoparticles are then proposed to lie above a layer of Ce3+ ions.