One-pot hydrothermal synthesis and high temperature thermal stability of CexZr1−xO2 nanocrystals

Abstract

We report a facile one–pot synthesis of Ce_xZr_1−xO₂ (0 ≤ x ≤ 1) solid solution nanocrystals using hydrothermal reactions. A direct formation of oxide solid solutions in aqueous solution under pressure at low temperatures was clearly revealed by X-ray diffraction, Raman spectroscopy, and chemical composition analysis of individual nanocrystals using energy dispersive X-ray spectroscopy in scanning transmission electron microscopy mode. Chemisorption behavior of the synthesized nanocrystals was characterized using a hydrogen temperature programmed reduction, which showed a superior low-temperature activity in Ce_xZr_1−xO₂ (0 < x < 1) compared to pure CeO₂. Furthermore, we investigated the thermal stability of the prepared Ce_0.5Zr_0.5O₂ at high temperatures (900 °C–1400 °C) under oxidation and reduction atmosphere. The effect of varying conditions of heat-treatment has given information on the phase transformation in Ce_0.5Zr_0.5O₂ from pseudocubic to tetragonal structure under oxidation atmosphere, and to pyrochlore structure under reduction atmosphere.