Catalytic Degradation of 4-Nitrophenol in Polluted Water by Three-Dimensional Gold Nanoparticles/Reduced Graphene Oxide Microspheres

Microspheres as catalysts catalyst supports have attracted a great deal of attention over the last two decades.Here, gold nanoparticles (Au-NPs) encapsulated within the reduced graphene oxide microspheres (rGO microspheres) were prepared by using a spray-drying method.The Au-NPs were distributed evenly through the rGO microsphere composite.The mass content of Au-NPs in the rGO microspheres composite reached 30.3%, and the average size of the Au-NPs was 10.5±2.5 nm.The morphologies and structural characteristics of the materials were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) patterns.The as-prepared composite was used to catalyze the reduction of 4-nitrophenol to 4-aminophenol in the presence of excess sodium borohydride and exhibited high catalytic activity.The catalysis process was monitored by UV spectroscopy, and the -3 -1 4first order rate constant of the catalytic reaction K was 1.96×10 s , and the activation energy E was found to be 3.5×10 J/mol.The catalytic a experiment results indicated the Au/rGO microspheres prepared have a great application for friendly environment aspects.