|Article title||IN SITU NUCLEATION AND GROWTH STUDIES NANOCATALYSTS BASED ON PT IN AN ATMOSPHERE OF HELIUM|
|Authors||N.M. Nevzorova, I.N. Leontyev, G.E. Yalovega|
|Section||SECTION II. NANOTECHNOLOGY, MICROELECTRONICS AND MICROELECTRONIC EQUIPMENT|
|Month, Year||12, 2015 @en|
|Abstract||Platinum based nanocomposite materials are widely used as catalysts for proton-exchange membrane fuel cells (PEMFC). The aim is to determine the kinetics of nucleation and growth, structural parameters nanosize platinum-based catalysts by heating in a helium atmosphere. Platinum acetylacetonate (II) (Pt(acac)2) was used as a precursor and inactive carbon Vulcan XC-72 was used as a support. Carbon supported pure Pt electrocatalysts were prepared by impregnating Pt(acac)2 precursor Vulcan XC-72. We have investigated the change features of XAFS spectra of formed in the gas phase nanoparticles by varying the temperature. We used He as a reducing gas. For direct control of the processes of formation of nanoparticles of Pt/C as a function of the synthesis conditions (T, heating time) we used XAFS (EXAFS and XANES) method. The X-ray absorption measurements of pure Pt catalysts in the Pt L3 absorption edge were carried out at the European Synchrotron Radiation Facility (France) using transmission mode. The measurements of the XAFS Pt L3-edge spectra were provided during the sample heating as a function of temperature. The temperature was raised from ambient temperature (~25°С) to 260°С under a flow of He. The changes in the shape of XANES spectra indicate to decomposition of Pt(acac)2 during the sample heating in helium atmosphere and supposedly formation of nanostructured platinum. A change of white line intensity of XANES with changes of Pt/C particle size was found. The temperatures of nucleation and growth of platinum nanoparticles were determined. In accordance of analysis of EXAFS data Pt nanoparticles formed on the carbon surface.|
|Keywords||Fuel elements; nanoparticles Pt/C; catalystst; XANES; EXAFS.|
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