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Platinum Nanoparticles (platinum + nanoparticle)
Selected AbstractsElectrochemical deposition of Pt nanoparticles on diamond substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2009Jingping Hu Abstract Platinum nanoparticles were deposited on polished smooth, as-grown large grain and small grain diamond substrates by a potentiostatic method. The influence of deposition potential and the morphology of BDD substrates were studied. A progressive nucleation along with spherical clusters was observed on smooth BDD electrode, accompanied with a heterogeneous segregation of platinum on diamond facets of higher electrochemical activities and a weak binding to the substrate. In contrast, an instantaneous nucleation was observed on as-grown small grain and large grain BDD electrodes, with a dendritic microstructure and a much larger specific active area. The platinum decorated as-grown smaller grain BDD electrodes show a much better electrochemical stability than the other electrodes investigated. [source] Preparation of Highly Active and Dispersed Platinum Nanoparticles on Mesoporous Al-MCM-48 and Their Activity in the Hydroisomerisation of n- OctaneCHEMISTRY - A EUROPEAN JOURNAL, Issue 19 2008Abstract Platinum nanoparticles supported on Al-MCM-48 materials have been prepared. The resultant catalysts have been characterized by means of XRD, N2 physisorption experiments, scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). The activity of these nanoparticles has been tested in relation to the hydroisomerisation of n- octane. The catalytic activities were typically 50,%, with selectivities in the isomerisation process in excess of 70,%, favouring the formation of the 3-methylheptane isomer with respect to the 2- and 4-methylheptanes. [source] Reagentless Biosensor for Hydrogen Peroxide Based on the Immobilization of Hemoglobin in Platinum Nanoparticles Enhanced Poly(chloromethyl thiirane) Cross-linked Chitosan Hybrid FilmELECTROANALYSIS, Issue 12 2009Shanshan Jia Abstract An unmediated hydrogen peroxide (H2O2) biosensor was prepared by co-immobilizing hemoglobin (Hb) with platinum nanoparticles enhanced poly(chloromethyl thiirane) cross-linked chitosan (CCCS-PNs) hybrid film. CCCS could provide a biocompatible microenvironment for Hb and PNs could accelerate the electron transfer between Hb and the electrode. Spectroscopic analysis indicated that the immobilized Hb could maintain its native structure in the CCCS-PNs hybrid film. Entrapped Hb exhibited direct electrochemistry for its heme Fe(III)/Fe(II) redox couples at ,0.396,V in the CCCS-PNs hybrid film, as well as peroxidase-like activity to the reduction of hydrogen peroxide without the aid of an electron mediator. [source] Platinum Nanoparticles Supported on Ionic Liquid-Modified Magnetic Nanoparticles: Selective Hydrogenation CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2007Raed Abu-Reziq Abstract A method for supporting platinum nanoparticles on magnetite nanoparticles is described. The method requires modification of the surface of the magnetic nanoparticles with ionic liquid groups. Before modification, the magnetic nanoparticles are not stable and easily aggregate and, after modification, the magnetite nanoparticles become highly stable and soluble in polar or non-polar organic solvents depending on the alkyl group of the linked ionic liquids. The supporting of platinum nanoparticles on the modified magnetic nanoparticles was achieved by adsorbing platinum salts (K2PtCl4) on the surface of the magnetite nanoparticles via ion exchange with the linked ionic liquid groups and then reducing them by hydrazine. The supported platinum nanoparticles were applied in the catalytic hydrogenation of alkynes in which cis -alkenes were selectively produced, and in the hydrogenation of ,,,-unsaturated aldehydes where the allyl alcohols were obtained as the exclusive products. The new catalyst can be easily separated from the reaction mixtures by applying an external magnetic field and recycled. [source] Luminol chemiluminescence catalysed by colloidal platinum nanoparticlesLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2007Sheng-Liang Xu Abstract Platinum colloids prepared by the reduction of hexachloroplatinic acid with citrate in the presence of different stabilizers were found to enhance the chemiluminescence (CL) of the luminol,H2O2 system, and the most intensive CL signals were obtained with citrate-protected Pt colloids synthesized with citrate as both a reductant and a stabilizer. Light emission was intense and reproducible. Transmission electron microscopy and X-ray photoelectron spectroscopy studies were conducted before and after the CL reaction to investigate the possible CL enhancement mechanism. It is suggested that this CL enhancement is attributed to the catalysis of platinum nanoparticles, which could accelerate the electron-transfer process and facilitate the CL radical generation in aqueous solution. The effects of Pt colloids prepared by the hydroborate reduction were also investigated. The application of the luminol,H2O2,Pt colloids system was exploited for the determination of compounds such as uric acid, ascorbic acid, phenols and amino acids. Copyright © 2006 John Wiley & Sons, Ltd. [source] Mesoporous Pt,SiO2 and Pt,SiO2,Ta2O5 Catalysts Prepared Using Pt Colloids as TemplatesCHEMPHYSCHEM, Issue 5 2007Vasile I. Pârvulescu Prof. Dr. Abstract Sol-gel synthesis of silica and silica,tantalum oxide embedded platinum nanoparticles is carried out using Pt colloids as templates. These colloids are prepared by reduction with Na[AlEt3H] and stabilized with different ligands (ammonium halide derivatives, non-ionic surfactants with polyether chains, and 2-hydroxy-propionic acid). The aim of the present study is to prepare mesoporous silica embedded Pt colloids combining the "precursor concept" with the model of catalyst preparation using preformed spheres. Nanoparticles of Pt incorporated in high surface area mesoporous materials are formed after calcination. Further, it is observed that calcination of these catalysts causes partial aggregation and oxidation of the parent colloids, a process that is largely dependent on the nature of the stabilizing ligands. Several methods have been used for characterization of these materials: adsorption-desorption isotherms at 77 K, H2 chemisorption, X-ray diffraction(XRD), 29Si and 13C magic angle spinning (MAS) NMR, ammonia diffuse reflectance Fourier transform infrared spectroscopy (NH3 -DRIFT), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It is found that both metal oxide systems exhibit Brønsted acidity (weaker for silica and quite strong for silica,tantalum oxide). In addition, NH3 -DRIFT experiments demonstrate the oxidative properties of the surface. Part of the adsorbed NH4+ species is oxidized to N2O. Testing these catalysts in the reduction of NO and NO2 with isopentane under lean conditions indicate that the activity of these catalysts is indeed dependent on the size of the platinum particles, with those of size 8,10 nm demonstrating the best results. The support likely contributes to this effect, particularly after Ta incorporation into silica. 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