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Tungsten oxide nanostructures functionalized with gold or platinum NPs are synthesized and integrated, using a single-step method via aerosol-assisted chemical vapour deposition, onto micro-electromechanical system (MEMS)-based gas-sensor platforms. This co-deposition method is demonstrated to be an effective route to incorporate metal nanoparticles (NP) or combinations of metal NPs into nanostructured materials, resulting in an attractive way of tuning functionality in metal oxides (MOX). The results show variations in electronic and sensing properties of tungsten oxide according to the metal NPs introduced, which are used to discriminate effectively analytes (C2H 5OH, H2, and CO) that are present in proton-exchange fuel cells. Improved sensing characteristics, in particular to H2, are observed at 250 °C with Pt-functionalized tungsten oxide films, whereas non-functionalized tungsten oxide films show responses to low concentrations of CO at low temperatures. Differences in the sensing characteristics of these films are attributed to the different reactivities of metal NPs (Au and Pt), and to the degree of electronic interaction at the MOX/metal NP interface. The method presented in this work has advantages over other methods of integrating nanomaterials and devices, of having fewer processing steps, relatively low processing temperature, and no requirement for substrate pre-treatment. Tungsten oxide nanoneedles functionalized with gold or platinum nanoparticles (NPs) are synthesized using a single-step aerosol-assisted chemical vapor deposition method. They are integrated into gas-sensor platforms, which are used to discriminate analytes present in proton-exchange fuel cells. This co-deposition method is demonstrated to be effective both for incorporating metal NPs into nanostructured materials, resulting in an attractive way of tuning functionality in metal oxides, and for directly integrating these materials with devices. Copyright © 2013 WILEY-VCH Verlag GmbH &

We have prepared tungsten oxide films decorated with gold particles on Si substrates by aerosol assisted chemical vapor deposition (AACVD) and characterized them using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). SEM shows that the films are composed of needle-like structures and TEM shows that both the needles and the gold particles are crystalline. XPS indicates the presence of oxygen vacancies, i.e. the films are WO 3-x, and hence the deposited material is composed of semiconducting nanostructures and that the interaction between the gold particles and the WO 3 needles surface is weak. The synthesis of semiconducting tungsten oxide nanostructures decorated with metal particles represents an important step towards the development of sensing devices with optimal properties. © 2012 Elsevier B.V. All rights reserved.

A new method of synthesising nanoparticle-functionalised nanostructured materials via Aerosol Assisted Chemical Vapour Deposition (AACVD) has been developed. Co-deposition of Au nanoparticles with WO(3) nanoneedles has been used to deposit a sensing layer directly onto gas sensor substrates providing devices with a six-fold increase in response to low concentrations of a test analyte (ethanol).

In this article is a report of SnO2 deposition by aerosol-assisted (AA)CVD from tin complexes, [Sn(18-Cr-6)Cl4] and [Sn(H2O)2Cl4](18-Cr-6). The structure and properties of the precursors, used to synthesize SnO2 layers by AACVD for the first time, are characterized with the help of X-ray diffraction (XRD), infrared (IR), and thermogravimetric analysis (TGA). Each complex is deposited by AACVD at 250, 400, and 500°C in a flow of N2. The resulting films are studied by XRD and atomic force microscopy (AFM). Gas-sensing properties of the deposited layers are tested to 10ppm NO2 in air. The maximum sensor response to the analyte is measured at 300°C. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In this doctoral thesis, it has been investigated and developed the Aerosol Assisted Chemical Vapour Deposition (AACVD) method for direct in-situ growth of intrinsic and Au-functionalised nanostructured WO3, as well as SnO2-based devices for gas sensing applications. The nanostructured material synthesis, device fabrication and their gas sensing properties have been studied. AACVD method was used for synthesis and direct deposition of sensing films onto classical alumina and microhotplate gas sensor substrates, demonstrating the compatibility between the microhotplate fabrication process and the sensing nanostructured layer deposition. The effect of Au nanoparticles on the gas sensor’s response was measured and presented in this thesis. The test results revealed that the addition of Au nanoparticles to the WO3 nanoneedles has increased the sensor’s response towards the tested gases (i.e. EtOH). It was therefore demonstrated that the Au-functionalisation has an enhancing effect on the gas sensing properties of WO3 nanoneedles, En esta tesis doctoral, se ha investigado y desarrollado un nuevo método de CVD asistido por aerosol (AACVD), que permite el crecimiento de nanoestructuras de WO3 intrínsecas y funcionalizadas con Au. Así mismo se han depositado capas policristalinas de SnO2 para aplicaciones de detección de gases. La síntesis de materiales nanoestructurados, la fabricación de dispositivos y sus propiedades de detección de gases, han sido estudiadas. El método AACVD fue utilizado para la síntesis y la deposición directa de capas activas encima de sustratos de alúmina y también sobre substratos micromecanizados (microhotplates), lo que demuestra la compatibilidad entre la tecnología de silicio y la deposición de la capas activas nanoestructuradas. En la tesis se ha demostrado que las capas nanoestructuradas de WO3 funcionalizadas con oro tienen una sensibilidad mejor que las intrínsecas frente a algunos gases relevantes y al mismo tiempo se ha producido un cambio de selectividad.