Comparative Study of CeO 2 and Doped CeO 2 with Tailored Oxygen Vacancies for CO Oxidation

• Published in: Chemphyschem 2011-10, Vol.12 (15), p.2763-2770
• Main Authors: Wang, Zhen, Wang, Qi, Liao, Yuchao, Shen, Genli, Gong, Xuzhong, Han, Ning, Liu, Haidi, Chen, Yunfa
• Format: Article
• Language: English
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201100346

We report on the preparation and characterization of CeO 2 nanofibers (CeO 2 ‐NFs) and nanocubes (CeO 2 ‐NCs), as well as Sm‐ and Gd‐doped CeO 2 nanocubes (Sm‐CeO 2 ‐NCs and Gd‐CeO 2 ‐NCs), synthesized by a simple hydrothermal process for CO catalytic oxidation. The samples were characterized by X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and photoluminescence spectroscopy. Their oxygen‐storing capacity (OSC) was examined by means of hydrogen temperature‐programmed reduction (H 2 ‐TPR) and oxygen pulse techniques. Their catalytic properties for CO catalytic oxidation were comparatively investigated. The results showed that the CeO 2 ‐NFs possessed a higher catalytic activity compared to the CeO 2 ‐NCs because of their smaller size and the greater number of oxygen vacancies. The activity of the Sm‐CeO 2 ‐NCs was higher than that of the CeO 2 ‐NCs due to an increase in the number of oxygen vacancies, which results from the substitution of Ce 4+ species with Sm 3+ ions. In contrast, Gd doping had a negative effect on the CO catalytic oxidation due to the special electron configuration of Gd 3+ (4f 7 ). Our work demonstrates that the oxygen vacancies in pure CeO 2 and the electron configuration of the dopants in doped CeO 2 play an important role in CO oxidation.