Stepwise construction of Pt decorated oxygen-deficient mesoporous titania microspheres with core-shell structure and magnetic separability for efficient visible-light photocatalysis

Solid photocatalysts with high specific surface area, superior photoactivity and ease of recycling are highly desired in chemical process, water treatment and so on. In this study, a facile stepwise sol-gel coating approach was utilized to synthesize Pt decorated oxygen-deficient mesoporous titania microspheres with core-shell structure and convenient magnetic separability (denoted as Fe3O4-@SiO2@Pt/mTiO(2-x)). These photocatalysts consist of magnetic Fe3O4 cores, nonporous insulating SiO2 middle layer and mesoporous anatase TiO2-x shell decorated by Pt nanoparticles (similar to 3.5 nm) through wet impregnation and H-2 reduction. As a result of high activity of oxygen-deficiency of black TiO2-x by H-2 reduction and efficient inhibition of electron-hole recombination by Pt nanoparticles, the rationally designed core-shell Fe3O4@SiO2@Pt/mTiO(2-x) photocatalysts exhibit superior photocatalytic performance in rhodamine B (RhB) degradation under visible light irradiation, with more than 98% of RhB degraded within 50 min. These core-shell structured photocatalysts show excellent recyclability under the assistance of magnetic separation with well-retained photocatalytic performance even after running five cycles. This stepwise synthesis method paves the way for the rational design of a high-efficiency recyclable heterogeneous catalyst, including photocatalysts, for various applications. (c) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.