Microwave-Assisted Synthesis of High-Energy Faceted TiO2 Nanocrystals Derived from Exfoliated Porous Metatitanic Acid Nanosheets with Improved Photocatalytic and Photovoltaic Performance

A facile one-pot microwave-assisted hydrothermal synthesis of rutile TiO 2 quadrangular prisms with dominant {110} facets, anatase TiO 2 nanorods and square nanoprisms with co-exposed {101}/[111] facets, anatase TiO 2 nanorhombuses with co-exposed {101}/{010} facets, and anatase TiO 2 nanospindles with dominant {010} facets were reported through the use of exfoliated porous metatitanic acid nanosheets as a precursor. The nanostructures and the formation reaction mechanism of the obtained rutile and anatase TiO 2 nanocrystals from the delaminated nanosheets were investigated. The transformation from the exfoliated metatitanic nanosheets with distorted hexagonal cavities to TiO 2 nanocrystals involved a dissolution reaction of the nanosheets, nucleation of the primary [TiO 6] 8？ monomers, and the growth of rutile-type and anatase-type TiO 2 nuclei during the microwave-assisted hydrothermal reaction. In addition, the photocatalytic activities of the as-prepared anatase nanocrystals were evaluated through the photocatalytic degradation of typical carcinogenic and mutagenic methyl orange (MO) under UV-light irradiation at a normal temperature and pressure. Furthermore, the dye-sensitized solar cell (DSSC) performance of the synthesized anatase TiO 2 nanocrystals with various morphologies and crystal facets was also characterized. The {101}/[111]-faceted pH2.5-T175 nanocrystal showed the highest photocatalytic and photovoltaic performance compared to the other TiO 2 samples, which could be attributed mainly to its minimum particle size and maximum specific surface area. View Full-Tex