ZrO2@Ag composite catalyst for hydrogenation reduction of organic dye: Preparation and characterization as well as catalytic performance evaluation

Amorphous monodisperse spheres of amino-functionalized zirconia (ZrO 2 ) were prepared by the co-condensation of zirconium tetrabutoxide as the precursor of ZrO 2 in the presence of aminopropyltriethoxy silane (APS) as the source of terminal amino groups. The resultant amino functional groups possess lone-pair electrons that can be coordinated with Ag seed colloid to immobilize the Ag seeds on the surface of ZrO 2 . Ag seeds tethered on the surface of the amino-functionalized ZrO 2 served as nucleation sites for the growth of Ag nanoshell overlayer via the reduction of AgNO 3 by polyvinylpyrrolidone (PVP), thereby affording core–shell structure ZrO 2 @Ag composite. The microstructure and chemical state of the as-prepared ZrO 2 @Ag composite were characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy, and its catalytic activity towards the hydrogenation reduction of Rhodamine B (RhB) and 4-nitrophenol (4-NP), two of common organic dye, was evaluated by ultraviolet–visible spectrophotometry. The results indicate that the uniformly distributed Ag nanoparticles with average size of 10 nm are strongly attached to ZrO 2 surface. Besides, the as-prepared ZrO 2 @Ag composite exhibits excellent catalytic performance for the hydrogenation reduction of RhB and 4-NP.