Synthesis and characterization of visible-light-active mesoporous titania by doping Ni and N

Abstract

Ultrafine TiO2 nanoparticles with a narrow size distribution were designed for extending the light absorption wavelength from ultraviolet to visible light with the increased photocatalytic activity. The mesoporous spherical TiO2 nanoparticles and the Ni doped TiO2 nanoparticles were prepared by sol–gel method, with the Ni molar fraction ranged from 0.5, 1, 2, 3, 4 to 5%. Samples were calcined at 550 °C to form crystallized TiO2 and eliminate organic impurities. The Ni and N co-doped TiO2 nanocrystals were prepared by heating Ni doped TiO2 powders in NH3 flow at 650 °C. All the doped titania nanocrystals are well crystallized anatase with a tetragonal structure. 0.5% Ni–TiO2 exhibited optimum photocatalytic activity for MB degradation under UV-light irradiation, which was about twice compared to that of the blank TiO2. The visible light photocatalytic activity of 5% Ni/N-TiO2 was remarkably raised up to 4 times by contrast with the blank TiO2 while the photocatalytic activity of N-TiO2 only increased to 2 times compared to that of the blank TiO2.