LAUSR

Abstract The redox properties of CeO2-WO3 mixed oxide supported on multi-walled carbon nanotubes (MWCNTs) and TiO2 were investigated in terms of valence state and active oxygen species. Ce-W/CNT and Ce-W/TiO2 were synthesized by impregnation method to support CeO2-WO3 mixed oxide on CNTs and TiO2. The interplanar distance of CeO2 in Ce-W/CNT was measured to be 0.316 nm by TEM and SAED pattern analysis, which was larger than that of Ce-W/TiO2 (0.310 nm), indicating the lattice expansion due to Ce3+ formation. Since the F2g and Ov peaks in Raman spectrum of Ce-W/CNT were broader than those of Ce-W/TiO2, it implied the increased oxygen vacancies of CeO2 supported on CNTs. In XPS analysis, Ce3+/(Ce4++Ce3+) ratios in Ce-W/CNT and Ce-W/TiO2 were 42.28 % and 28.60 %, and Oα/(Oα+Oβ) ratios were 29.07 % and 17.29 %, respectively. The redox properties of the catalysts were investigated by H2-TPR analysis. The reduction peak of Ce-W/CNT shifted to a lower temperature compared to Ce-W/TiO2, and H2 consumption increased by 1.91 mmol/g, increasing the redox properties. The reduction in the valence state of Ce4+ was caused by charge transfer between CNT and CeO2-WO3 mixed oxide, and the reduction promoted the formation of oxygen vacancies and active oxygen species.