Tuning the structural and catalytic properties of ceria by doping with Zr4+, La3+ and Eu3+ cations

This work attempts to gain information about the role of trivalent and tetravalent dopants on the structural and catalytic properties of ceria (CeO2). In this study, we have prepared Zr4+, La3+, and Eu3+ doped ceria (CZ, CL, and CE) by coprecipitation method and calcined at 773 K. The physicochemical characterization was achieved by using various techniques, namely, X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR) spectroscopy. The catalytic efficiency for soot oxidation was evaluated by thermogravimetric (TG) method and compared with undoped CeO2. Doped CeO2 catalysts decreased the soot oxidation temperature by more than 158 K compared to pure ceria. This is ascribed to mutual interaction and synergistic effect between the dopant species and the ceria. Among the synthesized nanocatalysts, the CE sample exhibited better performance. The observed better activity of CE was attributed to the presence of more number of oxygen vacancies, a high specific surface area, and easy reducibility as confirmed from Raman, BET surface area, and TPR measurements, respectively.