Biomimetic synthesis of micro/nanostructured tubular TiO2 photocatalyst: adjusting the shape of the outer tube wall from nanoparticles to interlaced nanofibers and nanobelts

In this study, hierarchical micro/nanostructured tubular TiO2 photocatalysts were fabricated with the fluff of the chinar tree (FCT) as a biological template and titanium tetrachloride (TiCl4) as a precursor through an impregnation–calcination method. The structure, morphology and optical properties were extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption–desorption, Fourier-transform infrared spectroscopy (FTIR), UV-vis diffused reflectance spectroscopy (UV-vis) and photoluminescence (PL) spectra. The results indicated that the FCT played pivotal roles as a template and inducer to assemble the tubular micro/nanostructure. Interestingly, the morphologies and structures of the outer tube wall of the obtained materials could be controlled and tailored by adjusting the dosages of TiCl4. In addition, the structures of the outer tube wall of the samples could be tuned from cross-linked nanobelts to interlaced nanofibers, and then spherical-likely nanoparticles by adjusting the dosages of TiCl4. Moreover, the as-prepared TiO2 material exhibited a 99.8% photocatalytic degradation rate for 15 mg L−1 rhodamine B (RhB) in 30 min under a 300 W mercury lamp. Compared with P25, the obtained TiO2 had superior photocatalytic activity. Furthermore, the hierarchical micro/nanostructured tubular TiO2 was easily recycled and had excellent photocatalytic stability.