Synthesis of One-Dimensional Ce_(1-x)Y_xO_(2-x/2) (0≤ x≤ 1) Solid Solutions and Their Catalytic Properties: The Role of Oxygen Vacancies

摘要

Oxygen vacancy plays a critical role in most enhanced performances of ceria-based materials. In this study, a facile hydrothermal method was developed for the synthesis of one-dimensional rare-earth doped ceria: Ce_(1-x)Y_xO_(2-x/2) (0≤ x≤ 1) .The doping concentration could be as high as 90% and the oxygen vacancies therein could be tuned in a wide range. The role of oxygen vacancies on the catalytic properties of these one-dimentional solid solutions had been systematically investigated. It was found that the amounts of the dopant (Y~(3+)) determined the concentration, type, and distribution of oxygen vacancies, which in turn influenced the reducibility and catalytic activity of the solid solutions: in the lightly doped ceria (x ≤0.1), oxygen vacancies formed associates with doped ions and improved the reducibility and catalytic activity of materials; with the dopants increased (0.1 ≤x ≤ 0.5), microdomains or C-type superstructures generated through the ordering of oxygen vacancies formed and decreased the catalytic activity of the solid solutions gradually; while in the heavily doped ceria, the reactivity of the solid solutions was drastically promoted; then, as the crystal transformed into the C-type structure (x > 0.9), the solid solutions suffered poor reactivity again. The present finding deepens the understanding of the nature of oxygen vacancies and may furtherly guide the design of highly reactive metal oxide catalytic materials.