Synthesis, microstructure, and properties of black anatase and B phase TiO2 nanoparticles

Abstract

We report the preparation of black TiO2 nanoparticles by UV irradiation of monodispersed TiO2-B nanoparticles with an average size of 5.0nm. After heating, the light-induced electron doping (Ti3+) TiO2-B nanoparticles in argon, air-stable black TiO2-B nanoparticles were obtained by heating at 340°C and further transformed to black anatase TiO2 by heating at 360°C. A characteristic single electron signal of electron paramagnetic resonance indicates oxygen vacancies with trapped electrons in black TiO2-B and black anatase TiO2. HRTEM images demonstrate that the black TiO2 samples have TiO2/TiO2−x core-shell heterostructures. Both of the black TiO2-B and black anatase TiO2 show room temperature superparamagnetic behavior and efficient photocatalysis under visible light.