Preparation Of Polyrrole Nanocomposites And Their Applications In Catalysis

With the gradual development of nanoscience, many people begin to payattention to micro-functionalized materials. Metal nanoparticles have drawn moreand more attentions due to their low density and large surface area. In this paper, weused template-assisted selectively etching method for preparation of Fe₃O₄@PPy/Pdyolk/shell structures and hard templates method for prearation of gold nanorods@carbon hollow capsules. And their structure and properties were explored as well.The morphology and composition of the composites were characterized by means ofScanning Electron Microscope（SEM）, Transmission Electron Microscope（TEM）,X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, Fourier TransformInfrared Spectroscopy（FT-IR）, Ultraviolet-Visible（UV-Vis） and grainsize analyzer.And their application in catalysis were explored as well.Firstly, we prepared Fe₃O₄@SiO₂composites, subsequently, thepolypyrrole（PPy） shell was covered on the surface of Fe₃O₄@SiO₂composites, thenyolk/shell Fe₃O₄@SiO₂@PPy composites formed. After selectively etching themiddle SiO₂layer, the yolk/shell Fe₃O₄@PPy composites were obtained. Yolk/shellFe₃O₄@PPy composites were used as supports for deposition of Pd nanoparticles.The morphology and composition of the composites were characterized by a seriesof means. By changing the dosage of tetraethylorthosilicate（TEOS）, the SiO₂shellthicknesses could be well controlled from16to45nm, suggesting the voidsbetween the Fe₃O₄core and PPy shell in yolk/shell Fe₃O₄@PPy composites couldrange from32to90nm. Fe₃O₄@PPy/Pd catalysts showed excellent catalyticactivity towards the reduction of methylene blue dye with sodium borohydride.Their catalytic property was improved with an increase of PdCl2dosage.Compared with traditional solid supporters, hollow capsules have attractedmore and more attentions due to their large surface area and low density, the mosteffective preparation way is hard-template method. This paper uses polystyrenenano-particles as a template, due to its low cost, simple preparation and convenientto removal. This template is usually negatively charged, and metal nanomaterialswith the positive charge of adsorption, we chose to use metal nanoparticles of goldnanorods（GNRs）. To avoid the phenomenon of the GNRs inevitably melted andaggregated, in our work, the GNRs were firstly embedded in the PPy shell, evenafter calcination at600°C, they still well preserved rod-like morphology withoutaggregations in carbon shell. Because of the melting under the high temperature,their aspect ratio reduced from original3.7to1.7. When concentration of pyrrole monomer increased from25.2to75.6mM, the PPy and corresponding carbon shellthicknesses increased from28to60nm and14to40nm. GNRs@C catalystsshowed excellent catalytic activity towards the reduction of methylene blue dyewith sodium borohydride.Their catalytic property was improved with an increase ofGNRs solution dosage.