Facile fabrication of polystyrene microsphere supported gold-palladium alloy nanoparticles with superior catalytic performance for the reduction of 4-nitrophenol in water

摘要

Herein a simple method is reported for depositing gold-palladium alloy nanoparticles NPs) with various chemical compositions on the surface of polystyrene microspheres abbreviated as PS/Au-Pd composite particles) based on a thermodynamic effect. Noticeably, surface pretreatments of PS microspheres and Au-Pd alloy NPs are not required at all for achieving the self-assembly of preformed heterogeneous particles. The Au-Pd alloy NPs act as steric stabilizer and attach spontaneously onto the surface of the PS microspheres to reduce the Gibbs free energy of the colloidal system. Afterwards, we investigate the catalytic properties of PS/Au-Pd composite particles for the reduction of 4-nitrophenol, which is of industrial significance for converting 4-nitrophenol a water pollutant with high toxicity) into 4-aminophenol an important intermediate of various industries). We have found that the catalytic activity of PS/Au-Pd composite particles is remarkably affected by the chemical composition of supported Au-Pd alloy NPs. The maximum activity is achieved in the case of supported alloy NPs having the Au/Pd molar ratio of 54:46, which is much higher than that of pure Au NPs and Pd NPs supported on the PS microspheres. Furthermore, these PS/Au-Pd composite particles can be easily recovered owing to the large size of PS microspheres and reused three times without significant loss of catalytic activity.