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An engineered multilayer structure of platinum-cadmium stannate-titanium oxide (Pt-CTO-TO), with different TO layer thickness (in the range 1-5 nm), has been grown at 400 °C on glass substrates by RF magnetron sputtering, following a 2-step procedure without breaking vacuum. To produce an alternative and reliable front contact for dye sensitized solar cells (DSCs), morphology and composition of a TO blocking layer have been studied, paying particular attention to the oxide-oxide (CTO-TO) interface characteristics. The influence of the metallic mesh on the transparent conductive oxide sheet resistance has also been considered. A sputtered CTO layer shows a high average transmittance, over 90%. The Pt mesh yields a drastic reduction in the series resistance, almost one order, without affecting the optical properties. The ultrathin blocking layer of Ti oxide prevents charge recombination, improving the overall performance of the solar cells: +86% in efficiency, +50% in short circuit current, with respect to bare CTO.

Nanostructured (3-6 nm) thin films (80 nm) of SnO2 and Pt-doped SnO2 were obtained by a new sol-gel route using tetra(tert-butoxy)tin(IV) and bis(acetylacetonato)platinum(II) as precursors. EPR and XPS investigations, performed on thin films after interaction with CO, demonstrated that singly ionized oxygen vacancies (V-o(.)) fully transferred their electrons to the noble metal and reduced Pt(IV) to Pt(ll). Contact with air at room temperature led to the reduction of O-2 to O-2(-), therefore, re-oxidizing metal centers. The reaction mechanism concords with the high electrical sensitivity of this material. (C) 2001 Elsevier Science B.V. All rights reserved.

Nanostructured (3-6 nm) thin films (80 nm) of SnO2 and Pt-doped SnO2 were obtained by a new sol-gel route using tetra(tert-butoxy)tin(IV) and bis(acetylacetonato)platinum(II) as metal precursors. The results of glancing incidence X-ray diffraction (GIXRD) and X-ray photoelectron spectroscopy (XPS) investigations demonstrated that platinum substituted for tin(IV) in the cassiterite structure. Electron paramagnetic resonance (EPR) and XPS analyses showed that singly ionized paramagnetic oxygen vacancies (Vo(.)) were formed on pure SnO2 thin films by interaction with CO atmosphere; in Pt-doped SnO2 films, the same defects Vo(.) fully transferred their electrons to the noble metal so that Pt(IV) became Pt(II) and Pt(0). Such samples successively exposed to air, at room temperature, reduced O-2 to O-2(-). The behavior was well-detected by EPR measurements, which showed on thin films the presence of Sn(IV)-O-2(-) species. The surface reactivity agrees with the results of the electrical measurements.

Pt/alpha-Fe2O3 nanocomposites were synthesized on fluorine-doped tin oxide (FTO) substrates by a sequential plasma enhanced-chemical vapor deposition (PE-CVD)/radio frequency (RF) sputtering approach, tailoring the overall Pt content as a function of sputtering time. The chemico-physical properties of the as-prepared systems were extensively investigated by means of complementary techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDXS), secondary ion mass spectrometry (SIMS), and optical absorption spectroscopy, and compared to those of the homologous Pt/alpha-Fe2O3 systems annealed in air prior and/or after sputtering. The obtained results evidenced that the material compositional, structural and morphological features, with particular regard to the Pt oxidation state and hematite nano-organization, could be finely tailored as a function of the adopted processing conditions. Pt/alpha-Fe2O3 systems were finally tested as photoanodes in photoelectrochemical (PEC) water splitting experiments, evidencing a remarkable interplay between functional performances and the above-mentioned material properties, as also testified by transient absorption spectroscopy (TAS) results.

An engineered multilayer structure of platinum-cadmium stannate-titanium oxide (Pt-CTO-TO), with different TO layer thickness (in the range 1-5 nm), has been grown at 400 °C on glass substrates by RF magnetron sputtering, following a 2-step procedure without breaking vacuum. To produce an alternative and reliable front contact for dye sensitized solar cells (DSCs), morphology and composition of a TO blocking layer have been studied, paying particular attention to the oxide-oxide (CTO-TO) interface characteristics. The influence of the metallic mesh on the transparent conductive oxide sheet resistance has also been considered. A sputtered CTO layer shows a high average transmittance, over 90%. The Pt mesh yields a drastic reduction in the series resistance, almost one order, without affecting the optical properties. The ultrathin blocking layer of Ti oxide prevents charge recombination, improving the overall performance of the solar cells: +86% in efficiency, +50% in short circuit current, with respect to bare CTO. © 2013 The Owner Societies.

The distribution of arsenic (As) in the soil, rice grain and straw of Kaudikasa, Rajnandgaon, central India is described. Speciation of monomethylarsenonate (MMA) and dimethylarsinite (DMA) and As(III) in the rice grain is presented. A remarkably high concentration of arsenic in soil is observed. The geogenic sources of arsenic and other metals in the soil were apportioned., QC 20130130