Catalytic Activity of Gold and Silver Nanoparticles Supported on Zinc Oxide

Gold (AuNPs) and silver (AgNPs) nanoparticles have been prepared by “one-pot” synthetic method in the presence of poly(N-vinylpyrrolidone) (PVP). Absorption spectra, size, morphology, and structure of AuNPs and AgNPs were studied by UV-Vis spectroscopy, DLS, SEM, and TEM. According to DLS measurements the average sizes of metal nanoparticles stabilized by PVP in aqueous solution are varied from 10 to 25 nm for AuNPs and from 6.5 to 44 nm for AgNPs. The impregnation method is used to support AuNPs and AgNPs on the surface of ZnO. The amount of AuNPs and AgNPs immobilized on the surface of ZnO does not exceed 0.2 wt.%. The catalytic activity of AuNPs and AgNPs supported on the surface of ZnO was evaluated with respect to decomposition of hydrogen peroxide. The optimal conditions for H2O2 decomposition were found to be dependent on of the amount of the catalyst, concentration of substrate, molecular weight of PVP, and temperature. The activation energy of H2O2 decomposition is equal to 44.1 kJ×mol-1. The decomposition of H2O2 in the presence of AuNPs and AgNPs supported on ZnO surface is discussed in the context of supramolecular catalysis mimicking catalase-like behavior. The recyclability of AuNPs supported on ZnO surface was tested.