Synthesis of small yolk–shell Fe3O4@TiO2 nanoparticles with controllable thickness as recyclable photocatalysts

Abstract

Core–shell nanophotocatalysts consisting of superparamagnetic cores and functional shells are intriguing in environmental remediation and biology. A few Fe₃O₄@TiO₂ particles have been developed in previous research studies, while most of them show a submicron-scale size and thick SiO₂ interlayers. Herein, we present a facile approach to prepare small Fe₃O₄@TiO₂ with a unique yolk–shell structure below 50 nm, in which most of the SiO₂ interlayers have been simultaneously etched off during synthesis. The prepared photocatalysts have been characterized by TEM, XRD, BET and VSM, and a formation mechanism is proposed. Controllable thickness of the TiO₂ shell has been achieved and its effect on their photocatalytic activities has also been investigated. These small yolk–shell Fe₃O₄@SiO₂ nanoparticles are expected to be applied in a variety of fields due to their low density, high surface area, superparamagnetic behavior and good photocatalytic activity.