Tailoring The Structure Of Titania With Enhanced Photocatalytic Activity

Recently, great attention has been paid to semiconductor photocatalysis due to itspotential in solving the problems of energy shortage and environment pollution. As oneof the most important semiconductor photocatalst, TiO₂has been used in many fieldssuch as photocatalytic degradation of organic contaminant, air purification, productionof hydrogen by water splitting and dye-sensitized solar cells. However, the widebandgap and low quantum efficiency （⁴%）, hampered the widespread practicalapplications of TiO₂. It is of great importance in exploring the photocatalyst with visiblelight response and/or high quantum efficiency.In this thesis, strategy for preparation of TiO₂-based photocatalyst with highphotocatalytic activity was studied from the viewpoints of semiconductor coupling,energy-facet tailoring and hollow microspheric effect, shown as follows:Section1: Flower-like Bi₂WO₆were prepared via hydrothermal route employingNa₂WO₄·2H₂O and Bi（NO₃）₃·5H₂O as precursors and polymeric PSS as additive. TiO₂nanoparticles were deposited on the surface of Bi₂WO₆followed by calcination. Theeffect of TiO₂on the photocatalytic activity of Bi₂WO₆/TiO₂composite wassystematically studied. It was found that the composite containing20wt.%TiO₂showsthe highest photocatalytic activity in degradation of Brilliant Red X3B dye. EnhancedUV-vis light absorption, improved adsorption to substrate and suppression of therecombination of photo-generated electron-hole pairs are responsible for theimprovement of the photocatalytic performance of Bi₂WO₆/TiO₂composite.Section2: Anatase TiO₂nanocrystals with tunable percentage of reactive {001}facets were rapidly fabricated by a microwave-assisted strategy （200℃for30min）.Not only the exposure of high-energy facets, but also surface chemistry shows intimaterelationship with the photocatalytic activity of high-energy TiO₂nanocrystals.Section3: Rapid synthesis of chain-like TiO₂hollow microspheres （TiO₂-HMS）was put forward, which was synthesized by hydrothermal reaction at low temperature（150℃） using （NH₄）₂TiF6as the titanium source, urea and H₂O₂as the morphologycontrolling agents. The fabrication of TiO₂-HMS can be greatly enhanced in thepresence of H₂O₂. The formation mechanism of TiO₂-HMS was discussed.