Varied crystalline orientation of anatase TiO2 nanotubes from [101] to [001] promoted by TiF62− ions and their enhanced photoelectrochemical performance

Herein, we report an ionic cross-linkage process of synthesizing [001] preferred oriented anatase TiO2 nanowires and nanotubes hybrid structure (TWTs) based on anodization method wherein varied amounts of TiF62− ions are added in synthetic process. We show how the TiF62− ions switch the growth direction of TWTs from [101] to [001] (denoted as T101WTs and T001WTs, respectively) and change their geometrical morphologies, i.e., small ionic radii TiF62− ions migrate and partly replace the TiO62− octahedra under electric field, which separate out and leave vacancies during annealing process, resulting in a reconstruction of TiO2. Importantly, absorption property and photoelectrochemical (PEC) performance of T001WTs exceed those of T101WTs. Furthermore, CdS QDs are assembled onto TWTs photoelectrodes by successive ionic layer adsorption and reaction technique. Likewise, T001WT/CdS presents superior absorption capability and enhanced PEC performance to those of T101WT/CdS. This could be attributed to their preponderances of improved light absorption capability and decreased electron recombination.