Synthesis and Characterization of Ce_1−<i>x</i>Eu_<i>x</i>O_{2−<i>x</i>/2} Mixed Oxides and Their Catalytic Activities for CO Oxidation

Abstract

A series of Ce 1− x Eu x O 2− x /2 mixed oxides was synthesized by coprecipitation. The solids were characterized by means of XRF, S BET, XRD, UV−vis, and Raman techniques, and their catalytic activities toward CO oxidation were tested. A solid solution, with CeO 2 F-type structure, is formed for europium contents (measured as Eu 2 O 3 by XRF) ≤20% wt. For higher contents, the solid solution is not formed, but a physical mixture is detected. The existence of oxygen vacancies in the solids with Eu 2 O 3 contents between 3 and 17% wt was demonstrated by the presence of bands at 532 and 1275 cm −1 in their Raman spectra. The catalytic performances of the solids correlate with the amount of these punctual defects in the solid solution.