Improving catalytic activity of supported Au nanoparticles depending on its density

Supporting density of Au nanoparticles on the surface of magnetic carrier was carefully investigated because of its great effect on the catalytic activity. Micro-sized magnetic polymer beads (Fe3O4@PMMA) were employed to immobilize Au nanoparticles due to its easy surface modification and rapid magnetic separation. By controlling the supporting density and particles size of Au NPs, the catalytic activity of immobilized Au NPs in reducing p-nitrophenol was effectively improved. When 10 nm Au NPs were employed to be immobilized on the magnetic carrier with the density of 4292 mu g/g, the catalytic activity of Fe3O4@PMMA/Au even approached to that of isolated Au NPs, which indicated that suitable supporting density of Au NPs might compensate some drawbacks of heterogeneous catalysts. It meant that the catalytic activity of Au NPs was not damaged even after its immobilization. Furthermore, this magnetic supported catalyst could be easily separated and recycled. After 23 runs of recycling, no significant loss of catalytic activity was found. This catalyst also performed high catalytic activity in continuous-flow column reactors, which showed much potential in practical application. (C) 2016 Elsevier B.V. All rights reserved.