Characterization and activity of mesoporous titanium dioxide beads with high surface areas and controllable pore sizes

Mesoporous titanium dioxide beads with high surface areas (over 90 m2/g) and tunable pore sizes (from 12.8 to 16.5 nm) were synthesized via a solvothermal process heating by microwave irradiation, with ammonia being used as both a source of nitrogen and a control agent for the mesoporous structure. Structural characterization indicated that the mesoporous TiO2 beads were composed of nanocrystals and pores and the beads possess a optical band gap energy of 3.11 eV. The doping nitrogen was in the form of NHx or NOx species and was adsorbed on surface of the beads, which caused changes to the surface electronic structure. The results show that the samples which possess higher-order structure, large surface area and well-defined crystallinity have the best performance in photocatalytic activities exhibited as evaluated in the degradation of methylene blue.