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

Abstract

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.