Local Structure and Redox Properties of Amorphous CeO(2)-TiO(2) Prepared Using the H(2)O(2)-Modified Sol-Gel Method

Amorphous CeO(2)-TiO(2) nanoparticles synthesized by the H(2)O(2)-modified sol-gel method were investigated in terms of the Ce-O-Ce and Ti-O-Ti linkage, local structure, and redox properties. The decrease in the crystallinity of CeO(2)-TiO(2) by H(2)O(2) addition was confirmed. The metal–oxygen linkage analysis showed the difference in size of the metal–oxygen network between crystalline CeO(2)-TiO(2) and amorphous CeO(2)-TiO(2) due to the O(2)(2−) formed by H(2)O(2). The local structure of CeO(2)-TiO(2) was analyzed with an extended X-ray absorption fine structure (EXAFS), and the oscillation changes in the k space revealed the disordering of CeO(2)-TiO(2). The decrease in Ce-O bond length and the Ce-O peak broadening was attributed to O(2)(2−) interfering with the formation of the extended metal–oxygen network. The temperature-programmed reduction of the H(2) profile of amorphous CeO(2)-TiO(2) exhibited the disappearance of the bulk oxygen reduction peak and a low-temperature shift of the surface oxygen reduction peak. The H(2) consumption increased compared to crystalline CeO(2)-TiO(2), which indicated the improvement of redox properties by amorphization.