Hydrothermal Synthesis Of Mesoporous Tio <sub> 2 </ Sub> And Its Photocatalytic Properties

Anatase TiO₂ nanoparticles with average particle size in 20nm and specific surface area in 67.49m²/g were prepared directly using titanium sulfate and urea as raw materials by a simple hydrothermal process at low temperature. The influence of hydrothermal treatment time, hydrothermal treatment temperature, the molar ratio and concentration of the reactants on the as-prepared samples was investigated via XRD and SEM. Their photocatalytic activities were valuated by the probe reaction of methly orange degradation. The results indicated that the degradation rate of methly orange is 97.7% after a 6-hour photocatalytic treatment and that TiO₂ nanopaticles still show high photocatalytic activity of 81.2% methy orange degradation rate after a three 6-hour photocatalytic treatment.The mesoporous TiO₂ powders were fabricated via the introduction of surfacant template into hydrothermal process and two-step calcinations was used to remove template. The obtained mesoporous TiO₂ through different templates were characterized by SXRD, BET absorption and HRTEM, and the acting mechanisms of different templates were discussed. It was found that the use of composite CTAB/P123 as a template led to the orderly mesoporous TiO₂ with 320.46m²/g in Sbet and 4.48nm in pore diameter, which degraded 98.1% of methly orange after 4-hour photocatalytic treatment, showing higher photocatalytic activity than nano-sized TiO₂. The results of SXRD and BET absorption indicated that the orderly mesoporous structure was still obtained after calcining at 350℃, got unstable with an further increase in calcining temperature and was destroyed completely after calcining at 500℃.