Reducibility of ZrO 2 /Pt 3 Zr and ZrO 2 /Pt 2D films compared to bulk zirconia: a DFT+U study of oxygen removal and H 2 adsorption

• Published in: Nanoscale 2017-05, Vol.9 (20), p.6866-6876
• Main Authors: Ruiz Puigdollers, Antonio, Pacchioni, Gianfranco
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c7nr01904a

Oxide reducibility is an important property that determines the chemical and physical behavior of the materials under working conditions. Zirconia is a non-reducible oxide that exhibits high resistance to the loss of oxygen and low reactivity towards hydrogen, two typical processes involved in oxide reduction. Oxide reducibility can change substantially by nanostructuring (e.g. formation of nanoparticles). In this study, we investigate theoretically by means of DFT+U calculations including dispersion interactions the properties of 2D zirconia films supported on a Pt Zr alloy and Pt metal surfaces, two systems recently prepared experimentally. The results show that the supported ZrO ultrathin films behave very differently from the corresponding bulk oxide, with a low formation energy of oxygen vacancies, and a clear tendency to split the H molecule homolytically with direct reduction of the oxide. The comparison of free-standing and supported ZrO films shows that these peculiar properties are not due to the formation of a 2D nanostructure, but rather to the presence of the metal support and of a metal/oxide interface. The results provide evidence for the uncommon properties of supported 2D oxides.