Nanocomposites and nanomaterials

Electrocatalytic investigation of Pt/TiO2 and N/Pt/TiO2 electrodes synthesized by sol-gel method
Linnik O.1, Ihnatiuk D.1, Smirnova N.1, Vorobets V.2, Kolbasov G.2
1 Chuiko Institute of Surface Chemistry of the NAS of Ukraine. General Naumov Str.,17, Kyiv-03680, Ukraine. 
E-mail: smirnat@i.ua
2 Institute of General & Inorganic Chemistry of National Academy of Sciences of Ukraine, Acad. Palladin Str. 32/34, 03680, Kyiv, Ukraine

Platinum supported materials have been widely applied in the catalytic reactions. Nitrogen and platinum co-doped titania matrix can be used as the photocatalysts for environmental purification, hydrogen production, carbon dioxide reduction, etc. under solar light. It is reported the influence of Pt ions content, the presence of nitrogen, synthesis procedure on the electrocatalytic properties of the electrodes. The sol-gel synthesis of mesoporous and nonporous doped titania is designed to obtain co-doped materials. The sol-gel method used for mesoporous films is based on the sol formation of titanium(IV) isopropoxide, platinum(II) acetylacetonate, a three-block copolymer Pluronic P123 as a template and acetylacetone as a stabilizing agent. The nonporous films are formed using the simpler and faster route based on the hydrolysis of titanium(IV) isopropoxide and platinum(II) acetylacetonate in ethanol medium. The different pretreatment procedures of the films (heating or heating and UV treatment) are expected to cause the formation of platinum in its different valence states within titania matrix.
Photoelectrochemical investigations of the Pt/TiO2 and N/Pt/TiO2 electrodes synthesized in the same manner using the titanium sheet instead of the glass have been carried out in the wavelength range of 250–600 nm in a quartz electrochemical cell under irradiation of a high-pressure xenon lamp. The Iph spectra are expressed in the units of quantum efficiency (electron/photon). Ag/AgCl electrode has been used as a reference one. Electrocatalytic activity of the films in the oxygen and hydrogen reduction has been studied by means of the current-voltage dependencies in the working range (0 – -1.3)V. Efficiency of mesoporous and nonporous Pt/N/TiO2 electrodes in the electrocatalytic hydrogen evolution reaction depends on the dopants’ ratio, pretreatment conditions and the electronic state of admixtures in TiO2 matrix. The synergetic effect of Pt and nitrogen co-doping leads to the higher values of current density І(Н2) in comparison with TiO2 films.