Preparation and photocatalytic activity of macro-mesoporous n-doped TiO₂

A visible-light-active nitrogen-doped titanium dioxide (N-TiO₂) photocatalyst, being of macro-mesoporous structure, was synthesized by the sol-gel method using a block copolymer as template and fromamide as nitrogen source. The effects of the block copolymer on the microstructrue and the visible light absorption activity were studied by the analysis of X-ray diffraction, low temperature nitrogen ad-sorption-desorption, and UV-Vis spectroscopy. The results showed that the materials were composed of anatase and brookite phase. When the concentration of the block copolymer was adjusted, the particle size, mesoporous pore size, and band gap of the materials varied in the range of 9-12 nm, 10-14 nm, and 2.98-2.76 eV, respectively. Furthermore, the pore size of macropores and the thickness of walls increased with the increase of the concentration of the block copolymer. The results of photodegradation of methyl orange showed that the macro-mesoporous N-TiO₂ possessed good photocatalytic activity. With the increase of concentration of the block copolymer, the efficiency and velocity of photodegradation increase.