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

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]