Decoration of Carbon Nanotubes with Gold Nanoparticles for Catalytic Applications
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Decoration of Carbon Nanotubes with Gold Nanoparticles for Catalytic Applications Wei Lü Shandong University at Weihai, Weihai 264209, PR. China Xicheng Ma1, Ning Lun, Shulin Wen School of Material Science and Engineering, Characterization and Analysis Center for Materials, 1 School of Chemistry and Chemical Engineering Shandong University, Jinan 250061, PR China ABSTRACT Gold nanoparticles supported on carbon nanotubes (CNTs) were prepared by using electroless plating technique. High-resolution transmission electron microscopy (HRTEM) has shown that spherical gold nanoparticles were homogeneously dispersed on the surfaces of the carbon nanotubes with a distribution of particle sizes sharply at around 3-4 nm in diameter. The results presented in this work will probably provide new catalysts with better performances. INTRODUCTION Recently, gold has attracted much attention in catalyst research and industrial chemistry since its “inertness” was disproved by using ultra-fin particles. It has been demonstrated that gold nanoparticles dispersed on metal oxides can exhibit high catalytic activities for various types of reactions, like the epoxidation of propene and the low temperature oxidation of CO [1]. Otherwise, the use of carbon nanotubes as potential catalyst supports is now attracting the interest of the catalytic community with evidence of unique metal/support interactions resulting in quite distinct catalytic behavior [2-4]. In the present work, we have tried to couple gold nanoparticles onto the sidewalls of CNTs by using a simple electroless plating technique. The purpose of us is to obtain new gold catalysts with improved performance, i.e. high activity and selectivity. Both high-resolution transmission electron microscope (HRTEM) and energy-dispersive X-ray spectroscopy microanalysis techniques (EDS) were used to investigate the composition and microstructures of the as-formed materials. EXPERIMENTAL DETAILS Synthesis and pretreatments of CNTs The multiwall carbon nanotubes (MWNTs) used in this work were produced by silica-supported cobalt catalysts catalytic decomposition of acetylene (C2H2) in a horizontal furnace equipped with a quartz tube at 1000 ℃ under N2 ambient. The so-formed powder of nanotubes-Co/SiO2 composite was first purified with an aqueous HF solution and nitric acid at
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room temperature in order to successively extract the CNTs by dissolution of the SiO2 and cobalt particles. The residues were then separated by filtration and washed with distilled water and dried at 100 ℃. Oxidized CNTs were then obtained by refluxing the ground CNTs powder in an H2SO4-HNO3 blend acid at 140 ℃ for about 6 h, then washed with distilled water. Samples after oxidation were characterized by a Philips Tacnai-20 high-resolution transmission electron microscope (HRTEM) operating at 200 KeV. A Perkin-Elmer 2000 FTIR spectrometer was applied to measure the diffusion reflectance infrared fourier transform (DRIFT) spectroscopy of the samples. Activation and electroless plating of CNTs with gold nanop
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