Poly(N-vinylpyrrolidone) Protected Gold and Silver Nanoparticles: Synthesis, Characterization and Catalytic Properties

摘要

Summary: Gold (AuNPs) and silver (AgNPs) nanoparticles protected by poly(Nvinylpyrrolidone)(PVP) and b-Cyclodextrine (b-CD) were prepared by Turkevich method and “one-pot” synthetic protocol. Absorption spectra, size, morphology, structure and thermal properties of AuNPs and AgNPs were studied by UV-Vis spectroscopy, DLS, SEM, TEM and DSC. According to DLS measurement the average size of AuNPs stabilized by PVP in aqueous solution is varied from 10 to 25 nm while the same parameter of AgNPs stabilized by PVP and b-CD was in the range of 7- 25 nm. PVP and b-CD protected AuNPs and AgNPs were deposited on aluminum and zinc oxides by impregnation method. It was found that the amount of AuNPs-PVP deposited onto Al_2O_3 and ZnO does not exceed 0.07-0.1%. SEM and TEM images reveal that the average size of AuNPs-PVP deposited on the surface of Al_2O_3 is arranged between 8 and 30 nm and coincides well with DLS measurement. The catalytic activity of polymer-protected AuNPs and AgNPs supported on the surface of Al_2O_3 and ZnO was evaluated with respect to decomposition of hydrogen peroxide. The optimal conditions for H_2O_2 decomposition in relation to catalysts amount, concentration of substrate and temperature was found. The rate of H_2O_2 decomposition in the presence of Al_2O_3/AuNPs-PVP exhibits an induction period, is dependentupon the molecular weight of PVP and increases in the following order: PVP-350 kD > PVP-40 kD > PVP-10 kD. The H_2O_2 decomposition rate in the presence of Al_2O_3/AuNPs-PVP is much higher than that of Al_2O_3/AgNPs-PVP.