Programmed synthesis of Pd@hTiO2 hollow core–shell nanospheres as an efficient and reusable catalyst for the reduction of p-nitrophenol

Abstract

Here, we report a facile synthesis approach to obtain a Pd@hTiO₂ hollow mesoporous nanocomposite composed of tiny Pd nanoparticles cores encapsulated within hollow TiO₂ mesoporous shells. The core–shell strategy efficiently prevents the aggregation of Pd NPs (Pd nanoparticles) in the high temperature calcination process and the leaching of Pd NPs for the catalytic reaction in a liquid phase. The catalyst was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N₂ adsorption/desorption, elemental analysis and inductively coupled plasma atomic emission spectrometry (ICP-AES). The synthesized catalyst exhibited high catalytic activity in the reduction of p-nitrophenol with NaBH₄ aqueous solution at room temperature. Furthermore, Pd@hTiO₂ had an excellent recyclability, evidenced by being extensively reused for eight times without any substantial loss of activity.