Preparation and Surface Reduction Behavior of CeO₂ Nanoparticle Layer on Al₂O₃(0001) Crystal Substrate

Abstract

The CeO₂ NP layer on Al₂O₃(0001) prepared by dipping method using CeO₂ NPs colloid solution showed less contacted state among the primary particles even after heat treatment at 1000°C in air. The surface reduction behavior of CeO₂ NP layer on Al₂O₃(0001) was investigated by XPS under the Ar⁺ sputtering in vacuum. The result indicates that Ar⁺ sputtering induced a considerable reduction of CeO₂ NP layer on Al₂O₃(0001) and its final ratio of Ce³⁺ was 79%. In comparison with CeO₂ powder, the difference between their final ratio of Ce³⁺ (79% and 68%) was small. Therefore, it was indicated that the Ar⁺ sputtering induced the reduction of Ce⁴⁺ to Ce³⁺ in CeO₂ by mainly physical effect, however the chemical effect in low oxygen pressure could be attributed to the local thermal energy transfer induced by kinetic energy of Ar⁺ ions. The substrate-stabilized and dispersed CeO₂ NPs showed slightly accelerated capacity in reducing behavior of CeO₂. [DOI: 10.1380/ejssnt.2018.172]