In this paper the method of electrochemical oxidation/dispersion of zinc using pulse alternating current with average density of 0.2:1.2 A/cm2 was used. The mixture of ZnO and Zn5(OH)8Cl2·H2O (simonkolleite) was obtained. The application of this product as a photocatalyst provides a practically full removal of methylene blue dye under UV light. When the sample is calcined at 400 °С the decomposition of simonkolleite with a ZnO formation occurs. It is accompanied by decrease in surface area and photocatalytic activity of the material.

Keywords: zinc oxide, nanoparticle, simonkolleite, pulse alternating current, morphology, photocatalysis, methylene blue

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

The catalytic activity of Pt/C and PtxNi/C electrocatalysts prepared by  borohydride methode was studed. It was established that the specific activity  of fresh prepared Pt3,7Ni/C  catalyst  in oxygen  electroreduction  reaction is higher in compare with Pt/C material. After treatment of Pt3,7Ni/C material in the hot acid  nickel in the surface layers of nanoparticles was dissolved and the composition of nanoparticles was changed to Pt5,6Ni. The electrochemical surface area of the Pt5,6Ni catalyst and specific activity was slightly decreased after corrosion treatment. 

Keywords: platinum electrocatalysts, corrosion stability of the nanoparticles, fuel cells, X-ray diffraction, borohydride synthesis