Preparation of hollow Nd/TiO2 sub-microspheres with enhanced visible-light photocatalytic activity

Abstract

Hollow Nd-doped TiO₂ sub-microspheres are synthesised via a controlled hydrolysis reaction, where carbon spheres are employed as the template. The building blocks of TiO₂ doped with Nd are deposited on the surface of carbon spheres and subsequently, the carbon spheres are removed by calcination in air. The structure and morphology of the hollow Nd/TiO₂ sub-microsphere composites are characterised by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), low temperature N₂ adsorption (Brunauer–Emmett–Teller analysis), simultaneous thermal analysis (TG-DTA), diffuse reflectance UV-vis spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The SEM and TEM micrographs reveal that the as-prepared hollow Nd/TiO₂ sub-microsphere composite has an average diameter of 100 nm and a special uniform morphology, where the hollow sub-microspheres are constructed by TiO₂ nano-chains, which resemble cage-like structures. The Nd-doped Nd/TiO₂ composites exhibit high visible light absorption capacity, high adsorption ability and high photocatalytic activity towards Rhodamine B (RhB). Further, the effect of neodymium content on the physical structure and photocatalytic properties of hollow Nd/TiO₂ sub-microspheres is investigated. Finally, it is concluded that the higher photocatalytic performance of as-prepared hollow Nd/TiO₂ sub-microspheres stems from their hollow structure comprised of Nd/TiO₂ nanostructures and a high light-harvesting efficiency.