Effect of Calcination Temperature on Surface Oxygen Vacancies and Catalytic Performance Towards CO Oxidation of Co3O4 Nanoparticles Supported on SiO2
- Received Date: 2011-09-20
Abstract: Co3O4/SiO2 catalysts for CO oxidation were prepared by conventional incipient wetness impregnation followed by calcination at various temperatures. Their structures were char-acterized with X-ray diffraction (XRD), laser Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR) and X-ray absorption fine structure (XAFS) spectroscopy. Both XRD and Raman spectroscopy only detect the ex-istence of Co3O4 crystallites in all catalysts. However, XPS results indicate that excess Co2+ ions are present on the surface of Co3O4 in Co3O4(200)/SiO2 as compared with bulk Co3O4. Meanwhile, TPR results suggest the presence of surface oxygen vacancies on Co3O4 in Co3O4(200)/SiO2, and XAFS results demonstrate that Co3O4 in Co3O4(200)/SiO2 con-tains excess Co2+. Increasing calcination temperature results in oxidation of excess Co2+ and the decrease of the concentration of surface oxygen vacancies, consequently the for-mation of stoichiometric Co3O4 on supported catalysts. Among all Co3O4/SiO2 catalysts,Co3O4(200)/SiO2 exhibits the best catalytic performance towards CO oxidation, demon-strating that excess Co2+ and surface oxygen vacancies can enhance the catalytic activity of Co3O4 towards CO oxidation. These results nicely demonstrate the effect of calcination temperature on the structure and catalytic performance towards CO oxidation of silica-supported Co3O4 catalysts and highlight the important role of surface oxygen vacancies on Co3O4.
|Citation:||Jin-bing Li, Zhi-quan Jiang, Kun Qian, Wei-xin Huang. Effect of Calcination Temperature on Surface Oxygen Vacancies and Catalytic Performance Towards CO Oxidation of Co3O4 Nanoparticles Supported on SiO2[J]. Chinese Journal of Chemical Physics , 2012, 25(1): 103-109. doi: 10.1088/1674-0068/25/01/103-109|