Synthesis and improved photocatalytic activity of ultrathin TiO₂ nanosheets with nearly 100% exposed (001) facets

Tremendous interest has been shown in the controllable synthesis and application of anatase TiO₂ nanomaterials with high percentage of reactive facets. In this work, ultrathin anatase TiO₂ nanosheets dominated by nearly 100% high-energy (001) facets were synthesized by using tetrabutyl titanate (TBT) and hydrofluoric acid (HF) as precursors. The morphological evolution of anatase TiO₂ nanosheets was studied by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM). As-prepared ultrathin TiO₂ nanosheets exhibited excellent photocatalytic activity toward the degradation of organic dye molecule rhodamine B (RhB) superior even to that of commercially available Degussa P25, due to the exposure of nearly 100% high-energy (001) facets and the effective suppression of recombination rates of photogenerated electrons and holes. These results demonstrate that the photocatalytic activity of anatase ultrathin TiO₂ nanosheets is highly dependent upon its exposed (001) facets, revealing important structure-property relationships in anatase TiO₂ nanosheets with specifically exposed (001) facets. The finding in this paper helps us further understand how shape variation, especially exposed (001) facets, influences the photocatalysis, it may also promote further development of anatase TiO₂ nanocrystals with tailored facets as well as the design and synthesis of other facet-exposed transition metal oxide nanomaterials.