Formation of TiO₂ Hollow Nanoparticles via Gas Phase Synthesis using Titanium Oxide Acetylacetonate as a Precursor

Abstract

TiO₂ nanoparticles were synthesized by chemical vapor condensation (CVC) using titanium oxide acetylacetonate as a precursor in the temperature range of 800-1000°C. TEM observation revealed that TiO₂ nanoparticles 10-40 nm in diameter consisted of a hollow structure with shells 4-5 nm in thickness. From XRD results, it was found that TiO₂ nanopowders obtained at all temperatures consisted of a two-phase rutile and anatase mixture. The sequential decomposition of the metal acetylacetonate precursor observed in thermogravimetry (TG) analysis showed that formation of the hollow structure depends on the characteristics of the metal-organic precursor. In addition, it was found that the transmittance of TiO₂ hollow nanoparticles is lower than that of commercial nanopowders in the wavelength range of 400-800 nm by UV-visible spectrophotometry. However, the band gap energy of the TiO₂ hollow nanoparticles at about 3.0 eV is unchanged from other forms of TiO₂.