Solvothermal Synthesis Of TiO₂Nanoparticles And Their Photocatalytic Activity In Degradation Of Gaseous VOCs

In recent years, volatile organic compounds （VOCs） are not only hazardous to humanhealth but also harmful to the environment. Among various VOCs, benzene and acetonehas been regarded as a priority hazardous substance. Semiconductor photocatalysts suchas TiO₂are found increasing applications in environmental remediation. Among variousmethods available for the preparation of TiO₂nanoparticles, the solvothermal techniquewhich facilitates the control of grain size, particle morphology, microstructure and phasecomposition obtained more and more attention.In this dissertation, TiO₂nanoparticleswere prepared via solvothermal method. Solvothermal synthesis of TiO₂nanoparticles,TiO₂hollow nanoparticles and N-doped TiO₂nanoparticles was studied in detail.Effects of different precursors and calcination temperatures on the structure,morphology and photocatalytic ability of the products were discussed in detail.TiO₂hollow nanoparticles were prepared by a hydrothermal method which wascalcined at different temperatures. Effects of calcination temperature on the structure andmorphology of the products were characterized in detail. Experimental results had shownthat the as-prepared TiO₂powders possessed hollow microsphere morphology withdiameter of about100nm, and calcination temperature altered the crystallinity,morphology, surface area and porous structure of the as prepared samples. Thephotocatalytic activity of the TiO₂powders was evaluated by the photocatalyticdegradation of gaseous acetone under UV-light irradiation in air. It was found that theTiO₂sample calcined at250oC exhibited the highest photocatalytic activity, whosephotocatalytic activity was higher than that of Degussa P25.Anatase-brookite mixed phase N-doped TiO₂nanoparticles were synthesized bysolvothermal method with ammonium nitrate. The synthesized materials werecharacterized by X-Ray diffraction （XRD）, Brunauer-Emmett-Teller （BET）, X-Rayphotoelectron spectroscopy （XPS）, Transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM）. The effects of dopingnitrogen on phase composition, particle size, microstructure, specific surface area wereinvestigated in detail. The photocatalytic activity of the sample was evaluated bydegradation of benzene in air under UV light irradiation. It is found that the N-TiO₂prepared with ammonium nitrate achieve much higher photocatalytic performance thansamples including PT and P25in the photocatalytic process. The amount of CO₂producedfrom the photocatalytic reaction is up to367.13mg/m³after150min.