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This work is focused on synthesis, characterization, and determination of main parameters of the multilayer P123 templated TiO2 films. The mesoporous multilayer thin films consist of TiO2 nanoparticles on the F-doped SnO2 (FTO) conductive glass substrates. The films were grown by implementing the protocol of supramolecular templating with the amphiphilic triblock copolymer, Pluronic P123. The templated multilayer films were manufactured by repeated dip coating followed by the thermal treatment at 350 °C for 2 h after deposition of each layer. It was found that the multilayer preparation technique at 350 °C has serious limitations. The structure does not further increase its specific surface area (roughness factor) after deposition of more than 3−5 layers. The new surface area added by deposition of the top layer is compensated by the reduction of the surface area lost due to the sintering of the bottom layers. The careful review of the analytical data suggests that the morphology of the P123 templated TiO...

Effect of the vapor-deposited Au nanoparticles on the rate of the Fe ( CN ) 6 - 3 / Fe ( CN ) 6 - 4 redox reaction at the highly oriented pyrolytic graphite (HOPG) electrode is investigated by cyclic and convolution potential sweep voltammetry. Surface morphology and electronic structure of Au deposits is studied by AFM and XP spectra measurements of Au 4f core electrons and of valence electrons, respectively. Au/HOPG surfaces are shown to have the morphology, which is characterized by the preferential deposition of Au nanoparticles along step edges and the formation of larger Au islands on HOPG planes. Au deposits after annealing have the electronic structure close to that of the bulk metal, they remain stable during voltammetric measurements of the Fe ( CN ) 6 - 3 / Fe ( CN ) 6 - 4 electron transfer, but they dissolve upon the surface oxide formation at far positive potentials. Dissolution does not allow using the usual electrochemical pretreatment, i.e., cycling the electrode potential between limits at which gold surface is oxidized and reduced, prior to kinetic measurements. The rate of the Fe ( CN ) 6 - 3 / Fe ( CN ) 6 - 4 electron transfer on the Au/HOPG electrodes increases with the increasing Au coverage. Apparent standard rate constant related the Au coverage attains a maximum of approximately 10% of the value for a polycrystalline Au electrode. It is proposed that slower kinetics is related to the presence of the adsorbed impurities on the Au/HOPG surface, or to a double layer effect. Linear diffusion and the Marcus kinetic model provide a plausible description of the electrode process at both the HOPG and Au/HOPG electrodes.

A nickel nanoparticle assembly was formed by vapour deposition on various single-crystal supports. The nanoparticle structure, distribution, composition and charge transfer properties were examined simultaneously by atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), mass spectroscopy (MS) and electrochemistry. The data obtained by applied analytical techniques were correlated. X-ray photoelectron spectroscopy (XPS) of nanoparticle assemblies deposited at ambient temperature revealed the Ni(II) oxidation state, while metallic Ni was found in nanoparticles grown at 300??C. The amount of nickel deposited on highly ordered pyrolytic graphite (HOPG) estimated by AFM was found to be an order of magnitude higher than that obtained from XPS analysis, while AFM and XPS data for silicon agree well. The discrepancy was discussed in terms of differences in support elastic properties and AFM-tip/surface interactions. Current?potential measurements of nanoparticle charge transfer reaction point to the high stability and low resistant Ohmic character of the nanoparticle/HOPG interface.

The extent of thermal template (tetra-propyl-ammonium: TPA+) removal from a silicalite-1 layer by heating in air was investigated. While a temperature of 330 °C was sufficient to eliminate all N-containing template species from the surface region of the layer (i.e., within a depth of ≈10 nm), their complete elimination from the bulk even at 550 °C was not achieved. This was caused by a series of reactions proceeding at high temperatures, involving the products of TPA+ thermal degradation. A substantial amount of C-containing template species remained in the sample even after a thermal treatment at 550 °C. A role the SiO2 phase of low organization present in the silicalite-1 layer plays in the retention of the products of thermal degradation has been proposed. Additionally, the stability of TPA+ irradiated by microwaves was examined. Only minor morphological changes of the layer upon thermal template removal were revealed by atomic force microscopy.

Electrochemical reductive doping and oxidative de-doping was employed to modify anatase photoelectrochemical properties in situ. Spectroelectrochemical (Raman) and surface analysis (XPS, STM) revealed that changes in surface composition are responsible for variations in the course of both dark and photoassisted charge transfer processes including sub-bandgap photoeffects. The amount of charge passed during electrochemical reduction and oxidation of the electrode served to control the doping process, the level of which was indicated by variations in the course of reactions taking place on the anatase/electrolyte interface. The electrochemical reduction and oxidation of anatase allowed the reversible alteration of the electron density and this influenced its performance as a photoelectrode.

Carbon nanostructures such a single wall carbon nanotubes (SWCNT), double wall carbon nanotubes (DWCNT) and fullerene peapods (e.g. C70@SWCNT) usually occur in the form of bundles. Here, we present application of a novel simple and versatile method for deposition of small isolated nanoribbons of carbon nanotubes on annealed gold surface. The nanoribbons were characterized by Raman spectroscopy and exhibit characteristic features of individual carbon nanostructures. The resonance condition allowed the observation of a distinct spectrum of one inner tube in the nanoribbon from DWCNT. The signal of inner tubes of isolated DWCNT nanoribbons was found to be up to 50 times stronger than the sum of signals of the corresponding tubes in buckypaper sample. This dramatic enhancement is assigned to SERS (surface enhanced resonant Raman scattering) effect.