Preparation of a magnetic mesoporous Fe3O4–Pd@TiO2 photocatalyst for the efficient selective reduction of aromatic cyanides†
Abstract
Herein, a hierarchical magnetic mesoporous microsphere was successfully prepared as a photocatalyst via a simple and reproducible route. Typically, Pd nanoparticles (NPs) were evenly dispersed on the surface of a magnetic Fe3O4 microsphere and then coated with a porous anatase-TiO2 shell to form Fe3O4–Pd@TiO2. The core–shell structure could efficiently suppress the conglomeration of Pd NPs during the calcination process at high temperatures as well as the shedding of Pd during the catalytic reaction process in the liquid phase. The as-prepared photocatalyst was characterized by TEM, XRD, XPS, VSM, and N2 adsorption–desorption. Fe3O4–Pd@TiO2 exhibits high photocatalytic activity for the selective reduction of aromatic cyanides to aromatic primary amines in an acidic aqueous solution. Moreover, this magnetic photocatalyst could be easily recovered from the reaction mixture by an external magnet and reused five times without significant reduction in its activity. The superior photocatalytic efficiency of the proposed photocatalyst may be attributed to its high charge separation efficiency and charge transfer rate, which are caused by the Schottky junction and large interface area. The results indicate that the strategy of coating the active noble metal sites with a mesoporous semiconductor shell has a significant potential for application in metal–semiconductor-based photocatalytic reactions.