Platinum based nanocomposite materials are widely used as catalysts for proton-exchange membrane fuel cells (PEMFC).Carbon supported pure Pt electrocatalysts were prepared by several methods including wet synthesis and electrochemical technique. The X-ray absorption measurements of pure Pt catalysts in the Pt L3 absorption edge were carried out at the Rigaku R-XAS using fluorescence mode. A change of white line intensity of XANES with changes of Pt/C particle size was found. The change of oxidation state of Pt/C nanoparticles, which may be the result of the interaction of nanoparticles with a carbon substrate, is shown. Also theoretical XANES spectra with decreasing interatomic distance Pt-Pt were calculated using FEFF8 code. It is well known that the decreasing of the Pt-Pt distance is one of the reasons of the positive influence of the catalytic activity toward the oxygen reduction reaction (ORR).

Keywords: XANES, nanoparticles, nanocatalysts, nanocomposites, composite materials