| 1. |
- Pardo, M., et al.
(författare)
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Data preprocessing enhances the classification of different brands of Espresso coffee with an electronic nose
- 2000
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 69:3, s. 397-403
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Tidskriftsartikel (refereegranskat)abstract
- Two different ways of preprocessing chemical sensor data are presented as a means to improve the interpretation and the classification ability of an electronic nose (EN). The practical problem at hand is the distinction between four commercial coffee blends - containing up to 12 types of coffees - all of which are to be consumed as Espresso. Coffee was sampled in three successive preparation phases: a beans, ground (powder) or liquid (the actual Espresso). In the case of beans, stress is put on the improved clusters visualization after the preprocessing and before the actual classification is performed. Different catalysed sensors and successive extractions were used to differentiate the response pattern towards the various coffees. The features which permitted the best samples' classification as judged from Principal Component Analysis (PCA) score plots were selected. To this end, an empirical search strategy inside the feature space is presented. Scores from PCA were subsequently utilized as inputs for a feed forward multilayer perceptron (MLP) with cross-validation resulting in 100% correct classification with just two sensors. In the case of ground coffee, a (supervised) drift compensation algorithm was developed. It essentially consists of removing the first principal component (PC) for every cluster since this is seen to be given by the drift. An 87.5% classification performance was achieved. Liquid coffee, on the other hand, was not successfully classified, probably due to the difficulty in assuring reproducible sampling conditions.
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| 2. |
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| 3. |
- Comini, E., et al.
(författare)
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Influence of iron addition on ethanol and CO sensing properties of tin oxide prepared with the RGTO technique
- 2006
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 115:2, s. 561-566
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Tidskriftsartikel (refereegranskat)abstract
- Effects of iron introduction in RGTO prepared tin oxide gas sensors are presented. The films were deposited by sputtering from a tin target with the introduction of an adjustable number or iron inset. Iron content was varied in the range 0-7%. The thin films are investigated by the volt-amperometric technique for electrical and gas-sensing properties. The layers are capable of sensing CO and ethanol, no evidence of surface poisoning is detected, and recovery of the resistance is complete. The response of the sensors is stable and reproducible at all operating temperatures tested (200-500 °C) during 3 months of operation. © 2005 Elsevier B.V. All rights reserved.
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| 4. |
- Sberveglieri, G., et al.
(författare)
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Preparation of transparent conducting oxide nanostructures for dye-sensitized solar cells
- 2008
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Ingår i: 2008 33rd IEEE Photovoltaic Specialists Conference. - Piscataway, NJ : IEEE Communications Society. - 9781424416417
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Konferensbidrag (refereegranskat)abstract
- ZnO, SnO2, Indium-tin oxide (ITO) nanostructures have been produced on glass substrates coated with a transparent conducting oxide (TCO) electrode for application in dye sensitized solar cells (DSC). Quasi one-dimensional (1D) nanostructures of different TCOs have been synthesized using the vapour transport-and-condensation technique. Nanostructures with different shape and aspect-ratio can be obtained by properly tailoring of the condensation conditions and the substrate preparation. A multi technique approach, using electron microscopy and DC electrical characterization, has been applied for micro-structural and functional characterization of the nanostructures. © 2008 IEEE.
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| 5. |
- Vomiero, Alberto, et al.
(författare)
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Integration of metal oxide nanowires in dye sensitized solar cells
- 2009
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Ingår i: 2009 34th IEEE Photovoltaic Specialists Conference : (PVSC 2009). - Piscataway, NJ : IEEE Communications Society. - 9781424429509 ; , s. 001325-001326
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Konferensbidrag (refereegranskat)abstract
- One of the most promising architectures of third generation solar cells is integration of single crystalline nanowires as electron transporters in anodes of electrochemical cells.[1-3] The nanowire-based cells aim at significantly increase cell efficiency thanks to the higher mobility of electrons along the single crystalline lattice of the nanowires with respect to traditional polycrystalline networks, greatly reducing electron-hole recombination controllable by passivation, functionalization or coaxial coating of the nanowire. The nanonetworks have been integrated in DSCs using the traditional N719 dye and the I-3/I-3 redox couple. The functional properties of the cells under 1 sun irradiation have been compared with traditional polycrystalline TiO2 photoanodes. ©2009 IEEE.
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| 6. |
- Bianchi, S., et al.
(författare)
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Indium oxide quasi-monodimensional low temperature gas sensor
- 2006
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 118:1-2, s. 204-207
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the sensing properties of indium oxide nanostructures and tailored the deposition conditions in order to obtain nano-wires of indium oxide. We have comparatively tested the gas sensing properties of nano-wires with micrometric or even nanometric size. The micro-wires feature interesting gas sensitivity at room temperature, particularly in the case of nitrogen dioxide detection. The sensing performance is improved as the lateral dimension of the wire decreases. © 2006 Elsevier B.V. All rights reserved.
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| 7. |
- Comini, E., et al.
(författare)
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Functional nanowires of tin oxide
- 2007
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 89:1, s. 73-76
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Tidskriftsartikel (refereegranskat)abstract
- Quasi-one-dimensional nanostructures of tin oxide were produced in controlled conditions through condensation from the vapor phase. The preparation was assisted by noble metal catalysts and uniform single-crystalline nanowires were produced. The nucleation of nanowires was achieved at 470 °C, owing to the vapor-liquid-solid growth mechanism activated by the catalytic Pt clusters. The peculiar microstructural properties of these semiconducting metal oxide nanostructures will be summarized. The high aspect ratio and the high degree of crystallinity achieved for the nanowires foresee their functional exploitation. © 2007 Springer-Verlag.
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| 8. |
- Comini, E., et al.
(författare)
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Quasi-one dimensional metal oxide semiconductors : Preparation, characterization and application as chemical sensors
- 2009
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Ingår i: Progress in Materials Science. - : Elsevier BV. - 0079-6425 .- 1873-2208. ; 54:1, s. 1-67
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Tidskriftsartikel (refereegranskat)abstract
- The continuous evolution of nanotechnology in these years led to the production of quasi-one dimensional (Q1D) structures in a variety of morphologies such as nanowires, core-shell nanowires, nanotubes, nanobelts, hierarchical structures, nanorods, nanorings. In particular, metal oxides (MOX) are attracting an increasing interest for both fundamental and applied science. MOX Q1D are crystalline structures with well-defined chemical composition, surface terminations, free from dislocation and other extended defects. In addition, nanowires may exhibit physical properties which are significantly different from their coarse-grained polycrystalline counterpart because of their nanosized dimensions. Surface effects dominate due to the increase of their specific surface, which leads to the enhancement of the surface related properties, such as catalytic activity or surface adsorption: key properties for superior chemical sensors production. High degree of crystallinity and atomic sharp terminations make nanowires very promising for the development of a new generation of gas sensors reducing instabilities, typical in polycrystalline systems, associated with grain coalescence and drift in electrical properties. These sensitive nanocrystals may be used as resistors, and in FET based or optical based gas sensors. This article presents an up-to-date review of Q1D metal oxide materials research for gas sensors application, due to the great research effort in the field it could not cover all the interesting works reported, the ones that, according to the authors, are going to contribute to this field's further development were selected and described. © 2008 Elsevier Ltd. All rights reserved.
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| 9. |
- Galstyan, V., et al.
(författare)
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Fabrication of pure and Nb-TiO 2 nanotubes and their functional properties
- 2012
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 536:SUPPL.1, s. S488-S490
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Tidskriftsartikel (refereegranskat)abstract
- TiO 2 and Nb-doped TiO 2 nanotubes were obtained on flexible polymeric substrates (Kapton HN) and alumina with high roughness (alumina substrate with granular surface). Nanotubes were prepared by electrochemical anodization of a Ti thick film. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to investigate the morphology of the structures and the roughness of the substrates. The functional properties of tubular arrays obtained on flexible and rough substrates were investigated towards two applications, namely, chemoresistive gas sensors and flexible dye sensitized solar cells. © 2011 Elsevier B.V. All rights reserved.
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| 10. |
- Galstyan, V., et al.
(författare)
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Fabrication of TiO 2 and TiO 2 nanotubular arrays and their gas sensing properties
- 2011
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Ingår i: Procedia Engineering. - : Elsevier BV. - 1877-7058. ; 25, s. 757-760
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Tidskriftsartikel (refereegranskat)abstract
- Pure TiO 2 and TiO 2 nanotubular arrays were successfully sensitized. Nanotubular arrays were prepared by electrochemical anodization of thin films of Ti and of Ti-Nb deposited on alumina substrates with two different roughness. Morphological characterization and functional properties are presented. The gas sensing properties of TiO 2 and TiO 2 nanotubes with different gases have been tested in a wide range of operating temperatures. © 2011 Published by Elsevier Ltd.
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| 11. |
- Galstyan, V., et al.
(författare)
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TiO 2 nanotubular and nanoporous arrays by electrochemical anodization on different substrates
- 2011
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 1:6, s. 1038-1044
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Tidskriftsartikel (refereegranskat)abstract
- The preparation of nanotubular arrays on different substrates and nanoporous structures on titanium foil by means of electrochemical anodization of titanium layer has been investigated. Highly aligned nanotubes of TiO 2 on flexible, rough and flat substrates are reported. Modification of anodization conditions of titanium on specific substrates such as polyethylene terephthalate (PET), conducting glass and granular alumina was found to affect the morphology of TiO 2 nanotubes. Two different kinds of aqueous electrolytes have been applied, containing either glycerol or H 2SO 4, in order to investigate the effect of ion mobility on anodization process. Galvanostatic and potentiostatic anodization modes have been investigated: transition from nanotubes to nanoporous structures has been highlighted in galvanostatic mode, depending on the intensity of anodization current density. These results pave the way for massive production of TiO 2 nanotubes over, in principle, whatever substrate, enabling exploitation of new functional properties derived from the combination of tubes and substrates. This journal is © The Royal Society of Chemistry 2011.
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| 12. |
- Sberveglieri, G., et al.
(författare)
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Semiconducting tin oxide nanowires and thin films for Chemical Warfare Agents detection
- 2009
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 517:22, s. 6156-6160
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Tidskriftsartikel (refereegranskat)abstract
- In this work we report the preparation and structural characterization of tin oxide nanowires as functional materials for the development of chemical sensors. Aspects of material preparation relevant for gas sensing applications, such as the control of the wire diameter, are emphasized. The functional characterization is focused on the detection of Chemical Warfare Agents (CWAs) simulants, with particular regard to poisoning effects induced by dimethyl methyl phosphonate (DMMP), a simulant for Sarin nerve agent. Tin oxide thin films, prepared by means of rheotaxial growth and thermal oxidation (RGTO) technique, are used as reference to better compare the performance of nanowires with thin films traditionally used in gas sensing field. © 2009 Elsevier B.V. All rights reserved.
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| 13. |
- Sberveglieri, G., et al.
(författare)
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Synthesis and characterization of semiconducting nanowires for gas sensing
- 2007
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 121:1, s. 208-213
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Tidskriftsartikel (refereegranskat)abstract
- Quasi one-dimensional nanostructures of semiconducting metal oxides are promising for the development of nano-devices. Tin, indium, and zinc oxides were produced in form of single-crystalline nanowires through condensation from vapor phase. Such a growth occurs in controlled thermodynamical condition and size reduction effects on the electrical and optical response to gases have been exploited. Preparation, microstructural, and electrical characterization of nanowires are presented and the peculiarities of these innovative structures are highlighted. © 2006 Elsevier B.V. All rights reserved.
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| 14. |
- Vomiero, Alberto, et al.
(författare)
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In2O3 nanowires for gas sensors : morphology and sensing characterisation
- 2007
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 515:23, s. 8356-8359
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Tidskriftsartikel (refereegranskat)abstract
- Thin and densely packed In2O3 nanowires have been synthesised on alumina substrates via transport and condensation method, starting from nanoparticles of indium or palladium as catalysts for the condensation process. Indium catalyst promoted wires growth according to vapour-solid (VS) mechanism, while palladium catalyst leads to wires formation based on vapour-liquid-solid (VLS) condensation. Electron microscopy and related diffraction analysis demonstrated that the wires are monocrystalline, with atomically sharp termination of the lateral sides, and are free from extended defects. The sensing properties of nanowires bundles have been tested to acetone using the flow through technique in the temperature range between 100 and 500 °C. © 2007 Elsevier B.V. All rights reserved.
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| 15. |
- Vomiero, Alberto, et al.
(författare)
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Nanoscience for innovative dye sensitized solar cells
- 2010
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Ingår i: ISOPE-2010, Beijing. - Cupertino, Calif : ISOFE. - 9781880653777 ; , s. 538-541
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Konferensbidrag (refereegranskat)abstract
- Innovative nanonetwork composed of oxide nanoparticles and single-crystalline ZnO nanowires is demonstrated as efficient photoanode in excitonic solar cells. Such architecture benefits of the capability of high sensitizer loading offered by the nanoparticles and of the direct conduction path for electrons guaranteed by the single-crystal nanowires. The combination of these features leads to improved light absorption, electron photogeneration, and charge collection. Various types of nanonetwork were implemented in a dye-sensitized solar cell architecture demonstrating great enhancement of the efficiency with respect to a nanowire photoanode of the same thickness. © 2010 by The International Society of Offshore and Polar Engineers (ISOPE).
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| 16. |
- Vomiero, Alberto, et al.
(författare)
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One-dimensional nanostructured oxides for thermoelectric applications and excitonic solar cells
- 2012
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Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855. ; 1:3, s. 372-390
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Tidskriftsartikel (refereegranskat)abstract
- Among the most interesting features offered by one-dimensional (1D) nanostructured oxides are their functional properties that can be usefully exploited in the field of energy conversion, in applications such as thermoelectrics and excitonic solar cells. Peculiar characteristics of 1D oxide structures with respect to polycrystalline or bulk counterpart, mainly related to their adjustable electronic conduction, render them strong candidates for the next generation of energy conversion devices. Furthermore, many of these materials are characterized by low-cost production, are non-toxic and relatively easy to produce, allowing a good perspective in large-scale assembly for the fabrication of end-user devices. In this paper we review the most recent achievements on 1D nanostructured oxides applied to thermoelectric devices and excitonic solar cells, highlighting the benefits offered by 1D shape on the functional properties of the devices and the possibility to manage energy transduction mechanisms in more efficient ways. © 2012 Elsevier Ltd.
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| 17. |
- Vomiero, Alberto, et al.
(författare)
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Preparation of radial and longitudinal nanosized heterostructures of in2O3 and SnO2
- 2007
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 7:12, s. 3553-3558
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Tidskriftsartikel (refereegranskat)abstract
- Radial and longitudinal nanosized In2O3-SnO 2 heterostructures were produced by applying a suitable methodology of transport and condensation. Sequential evaporation-condensation over In-seeded alumina promotes the formation of a radial heterostructure, driven by the direct vapor-solid growth mechanism. The single-crystalline In 2O3 nanowire nucleates and acts as the backbone for condensation of a polycrystalline SnO2 sheath. Fabrication of longitudinal heterostructures over sapphire is achieved through the application of a nanosized gold catalyst: the gold particles promote nucleation according to the vapor-liquid-solid mechanism, and lead to the formation of single-crystalline In2O3 nanowires with a gold droplet at the apex. Gold maintains its catalytic activity even during subsequent evaporation of SnO2 and induces the nucleation of a SnO2 single-crystal nanowire from the termination of an In2O3 nanowire. The electrical characterization of the longitudinally assembled In2O3-SnO2 structure highlighted a peculiar behavior, as the heterojunction of two n-type semiconducting oxides was revealed, tin oxide being reversely biased. These results hold great potential for the application of precisely shaped heterojunctions. © 2007 American Chemical Society.
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| 18. |
- Vomiero, Alberto, et al.
(författare)
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ZnO/ TiO2 nanonetwork as efficient photoanode in excitonic solar cells
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 95:19
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Tidskriftsartikel (refereegranskat)abstract
- An innovative nanonetwork composed of TiO2 nanoparticles and single-crystalline ZnO nanowires is demonstrated as efficient photoanode in excitonic solar cells. Such architecture benefits of the capability of high sensitizer loading offered by the nanoparticles and of the direct conduction path for electrons guaranteed by the nanowires. The combination of these features leads to improved light absorption, electron photogeneration, and charge collection. The nanonetwork was implemented in a dye-sensitized solar-cell architecture demonstrating threefold enhancement of the efficiency with respect to a nanowire photoanode of the same thickness. Cell efficiency of 1.6% was obtained in 1.5 μm thick nanonetwork. © 2009 American Institute of Physics.
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