Synthesis And Catalytic Property Of Ag/PPY/Fe₂O₃Composite Nanoparticles

Hematite (a-Fe2O3) is thought of an important semiconductor. Conductive polypyrrole (PPY) has been attracted more attention because of its high conductivity, inoxidizability, softness and innocuity. In this thesis, the hematites were employed as cores, the PPY as shell and the silver nanoparticles were deposited on the surface of PPY/Fe2O3composite to obtain the core/shell/shell particles.As a conductive polymeric material, polypyrrole can transport its charges effectively to active sites of catalyst surface, increasing the negative electronic properties of the catalyst, which can improve the selectivity and catalytic activity of silver.Monodispersed and pseudo-spherical a-Fe2O3with average size of50nm were prepared by forced hydrolysis of FeCl3.PPY/Fe2O3composite nanospheres with well-defined core/shell structure were obtained through in-situ Polymerization. The effects of different reaction conditions on the structure of core-shell particles were discussed. The morphology structure and composition of the products were characterized by transmission electronic microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy The results showed, the optimum conditions for synthesis PPY/Fe2O3composite nanoparticles were as follows:the concentration of ppyrrole was1.25×10-2mol-L-1, PVP as surfactant, reaction time was8h and the reaction temperature was25℃.The Ag/PPY/Fe2O3composite nanospheres with shell/shell/core structures were prepared through the redox reaction between silver nitrate and polypyrrole at20℃,40℃and60℃respectively. TEM, XRD, FT-IR and UV-Vis were also used to character the composite particles. The catalytic reduction of sodium3-nitrobenzene sulfonate and RHB were used as probe to study the catalytic property of Ag/PPY/Fe2O3composite nanoparticles. The results showed, the catalytic activity of Ag/PPY/Fe2O3prepared at60℃with more content of silver was better than the Ag/PP Y/Fe2O3prepared at40℃.