| AVS 54th International Symposium | |
| Advanced Surface Engineering | Wednesday Sessions |
| Session SE-WeM |
| Session: | Photocatalytic Coatings |
| Presenter: | K.S. Lin, Yuan Ze University, Taiwan, R.O.C. |
| Authors: | K.S. Lin, Yuan Ze University, Taiwan, R.O.C. W.R. Chen, Yuan Ze University, Taiwan, R.O.C. C.F. Wu, Yuan Ze University, Taiwan, R.O.C. |
| Correspondent: | Click to Email |
A core-shell structured composite, nanophase titania coated Ni-, or Zn-ferrites nanoparticles, not only reserve the characteristics and advantages of TiO2 but also have the strong ferromagnetism of the ferrites. Therefore, the main objective of this study was to synthesize TiO2/nickel or zinc ferrite nanocomposites with spinel structure. In addition, it focused on the magnetic characteristics of the TiO2 surface-modified Zn or Ni-ferrite nanoparticles, which was expected to prepare a magnetically separable TiO2 photocatalyst. Experimentally, nickel or zinc ferrite core nanoparticles were synthesized under hydrothermal conditions by precipitating from metal nitrates with aqueous ammonia. TiO2 coated on the surface of the nickel or zinc ferrites were then prepared by hydrolysis of titanium chloride in the presence of ferrite nanoparticles. The optimal synthetic conditions included pH values of 8~9 and sintering at 673-773 K. The obtained ferrites or TiO2/Ni-, Zn-ferrites samples were characterized by XRD, FE-SEM, and TEM techniques. The results indicated that the size of nanoshell of TiO2 with anatase structure was 20-50 nm. X-ray absorption near edge structure (XANES) or extended X-ray absorption fine structure (EXAFS) was performed to identify the fine structures and oxidation state of Ni- or Zn-ferrites and anatase-typed TiO2 coated ferrites nanoparticles. By using XANES spectra, Ni- or Zn-ferrites may exhibit an absorbance feature for the 1s to 3d transition can reveal the occupation of tetrahedral sites within the lattice, it showed that Ni ferrite had the same reverse spinel structure with Fe3O4 and the valence of hydrogenated ferrites were between 2 and 3. When the sintered temperature arrive 723 K, the nanoshell of TiO2 would transform from amorphous to anatase, and the nanoshell of TiO2 photocatalysts were all Ti (IV). The EXAFS data revealed that the nanoshell TiO2 photocatalyst had first, second shell of Ti-O, and third shell of Ti-Ti with bond distances of 1.96 ± 0.01, 2.01 ± 0.01, and 3.05 ± 0.01 Å, respectively.