Hierarchical TiO2 nanoflowers/nanosheets array film: synthesis, growth mechanism and enhanced photoelectrochemical properties

Abstract

The possible growth mechanism of a hierarchical TiO₂ nanoflower/nanosheet (NFS) array was put forward in the work. The TiO₂ NFS array film perpendicularly grown on transparent conductive fluorine-doped tin oxide (FTO) glass substrates was prepared via a one-step template-free hydrothermal method. The NFS array film was formed by the self assembly of nanosheets with exposed highly reactive {001} facets. Titanium butoxide and ammonium hexafluorotitanate ((NH₄)₂TiF₆) were used as titanium precursor and morphology controlling agent, respectively. The growth process of TiO₂ NFS array was investigated according to the SEM images and XRD patterns of the products at different reaction stages. The tractable morphology controlling agent played a key role in the preparation of pure anatase TiO₂ and affected the thickness of the nanosheets. This study provides new insights into the synthesis of hierarchical anatase TiO₂ nanostructures with a high percentage of {001} facets. In addition, the photoelectrochemical performance of the CdS QDs sensitized TiO₂ NFS array film was assessed, indicating a variety of applications such as dye-sensitized or quantum dot-sensitized solar cells fields.