Preparation and properties of amorphous titania-coated zinc oxide nanoparticles

• Published in: Journal of solid state chemistry 2006-07, Vol.179 (7), p.2020-2026
• Main Authors: Liao, Min-Hung, Hsu, Chih-Hsiung, Chen, Dong-Hwang
• Format: Article
• Language: English
• Subjects: Core-shell; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; FOURIER TRANSFORMATION; Growth from solutions; INFRARED SPECTRA; LAYERS; MATERIALS SCIENCE; Methods of crystal growth; physics of crystal growth; Nanoparticles; Nanopowders; Nanoscale materials and structures: fabrication and characterization; NANOSTRUCTURES; PHOTOLUMINESCENCE; Physics; RAMAN SPECTRA; TiO 2; TITANIUM OXIDES; TRANSMISSION ELECTRON MICROSCOPY; ZINC OXIDES; ZnO
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2006.03.042

Amorphous TiO 2-coated ZnO nanoparticles were prepared by the solvothermal synthesis of ZnO nanoparticles in ethanol and the followed by sol–gel coating of TiO 2 nanolayer. The analyses of X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the resultant ZnO nanoparticles were hexagonal with a wurtzite structure and a mean diameter of about 60 nm. Also, after TiO 2 coating, the TEM images clearly indicated the darker ZnO nanoparticles being surrounded by the lighter amorphous TiO 2 layers. The zeta potential analysis revealed the pH dependence of zeta potentials for ZnO nanoparticles shifted completely to that for TiO 2 nanoparticles after TiO 2 coating, confirming the formation of core-shell structure and suggesting the coating of TiO 2 was achieved via the adhesion of the hydrolyzed species Ti–O − to the positively charged surface of ZnO nanoparticles. Furthermore, the analyses of Fourier transform infrared (FTIR) and Raman spectra were also conducted to confirm that amorphous TiO 2 were indeed coated on the surface of ZnO nanoparticles. In addition, the analyses of ultraviolet–visible (UV–VIS) and photoluminescence (PL) spectra revealed that the absorbance of amorphous TiO 2-coated ZnO nanoparticles at 375 nm gradually decreased with an increase in the Ti/Zn molar ratio and the time for TiO 2 coating, and the emission intensity of ZnO cores could be significantly enhanced by the amorphous TiO 2 shell. Amorphous titania-coated ZnO nanoparticles with a core-shell structure were prepared. It was found that the emission intensity of ZnO cores could be significantly enhanced by the amorphous TiO 2 shell.