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119 results on '"Dal Santo V."'

6. Hot Electron Collection on Brookite Nanorods Lateral Facets for Plasmon-Enhanced Water Oxidation

Author

Naldoni, A, Montini, T, Malara, F, Mroz, M, Beltram, A, Virgili, T, Boldrini, C, Marelli, M, Romero-Ocana, I, Delgado, J, Dal Santo, V, Fornasiero, P, Naldoni A., Montini T., Malara F., Mroz M. M., Beltram A., Virgili T., Boldrini C. L., Marelli M., Romero-Ocana I., Delgado J. J., Dal Santo V., Fornasiero P., Naldoni, A, Montini, T, Malara, F, Mroz, M, Beltram, A, Virgili, T, Boldrini, C, Marelli, M, Romero-Ocana, I, Delgado, J, Dal Santo, V, Fornasiero, P, Naldoni A., Montini T., Malara F., Mroz M. M., Beltram A., Virgili T., Boldrini C. L., Marelli M., Romero-Ocana I., Delgado J. J., Dal Santo V., and Fornasiero P.

Abstract

Photocatalytic reactions could enhance the share of chemicals produced through renewable sources. The efficiency of photocatalysts drastically depends on light absorption, on the surface energy of the crystals, and on the properties of the nanobuilding blocks assembled in devices. Here, we show that photoelectrochemical water oxidation on brookite TiO2 nanorods is greatly enhanced by engineering the location of Au nanoparticles deposition. Brookite photoanodes show a very low onset potential for water oxidation to H2O2 of -0.2 VRHE due to energetics of exposed crystal facets. By combining electrochemical measurements and ultrafast optical spectroscopy, we link the water oxidation activity with electron-hole recombination phenomena. The preferential Au decoration at the electrode/water interface produces highly enhanced photocurrent, while when Au is distributed along the whole film thickness, the activity is depressed with respect to pure brookite. In the latter case, Au nanoparticles act as recombination centers with plasmonic carriers recombining on the same time scale of their generation (fs). Conversely, Au surface decoration enables a hot electrons lifetime 4 orders of magnitude longer (ns) due to efficient hopping on brookite lateral facets, thus providing an efficient path for plasmon-enhanced solar water oxidation. (Graph Presented).

Published
2017

15. Enhanced photocatalytic activity of titania nanotubes by ligand-free Au nanoparticle loading

Author

Strini A., Schiavi L., Pedeferri M.P., Diamanti M.V., Evangelisti C., Marelli M., and Dal Santo V.

Subjects
Photocatalysis, titania nanotubes, Au-TiO2
Abstract

In the last years titania nanotubes arrays (TNTAs) have attracted increasing attention in photocatalysis due to their unique properties, not least the possibility of a direct production of supported TNTAs by anodic oxidation of metallic titanium foils. Besides, loading of TiO2-based photocatalysts with Au nanoparticles (NPs) has been extensively investigated so as to improve the photocatalytic efficiency. In order to combine the advantages of TNTAs with Au NPs decoration and to overcome the problems derived from current deposition methods this work proposes a simple and scalable synthetic protocol able to load size-controlled (10 µg cm-2) a pronounced deactivation was observed. Using the described method the Au loading was finely tuned ranging from 1.5 to 11.6 ?g cm-2 by controlling the support/Au dipping time without significant change of Au NPs mean size. No further thermal or chemical post-treatments were necessary. The Au loadings strongly influenced the photocatalytic activities and the best performance results in a three times enhancement of the bare TNTAs activity obtained with a sample containing 3.3 ?g cm-2 of Au. The proposed protocol demonstrated a remarkable enhancement of the photocatalytic activity of metal-supported TNTAs at room temperature without any post-deposition process.

Published
2016

17. Pt and Au/TiO2 photocatalysts for methanol reforming: Role of metal nanoparticles in tuning charge trapping properties and photoefficiency

Author

Naldoni, A, D'Arienzo, M, Altomare, M, Marelli, M, Scotti, R, Morazzoni, F, Selli, E, Dal Santo, V, Dal Santo, V., D'ARIENZO, MASSIMILIANO, SCOTTI, ROBERTO, MORAZZONI, FRANCA, Naldoni, A, D'Arienzo, M, Altomare, M, Marelli, M, Scotti, R, Morazzoni, F, Selli, E, Dal Santo, V, Dal Santo, V., D'ARIENZO, MASSIMILIANO, SCOTTI, ROBERTO, and MORAZZONI, FRANCA

Abstract

Metal-loaded TiO2 is, by far, one of the most important class of photocatalysts in hydrogen production through photoreforming of organics and water photosplitting. In this study anatase loaded with Au and Pt nanoparticles (Au/TiO2 and Pt/TiO2) by an impregnation-reduction method was investigated as for morphological, electronic (XPS) and photocatalytic properties in hydrogen production by methanol photoreforming. The electron and hole trapping centers, Ti3+ and O-, respectively, formed under UV-vis irradiation of the photocatalysts, were studied by in situ electron spin resonance (ESR) spectroscopy. The nature of the loaded metal affected both the H2 evolution rate and the distribution of the methanol oxidation products. The better performance of Pt/TiO2 is attributable to the greater ability of Pt with respect to Au to act as electron sink, slowering the recombination of photoproduced electron-hole couples. Direct evidence of this effect was obtained by ESR analysis, showing that the amount of Ti3+ active sites follows the order TiO2>Au/TiO2Pt/TiO2, thus confirming easier electron transfer from Ti3+ to Pt, where the H+ reduction to H2 occurs. © 2012 Elsevier B.V.

Published
2013

23. Electrochemically-assisted Deposition on TiO2 Scaffold for Tissue Engineering: an Apatite Bio-Inspired Crystallization Pathway

Author

Naldoni, A., Minguzzi, A., Vertova, A., Dal Santo, V., Borgese, L., and Bianchi, C. L.

Abstract

The interactions among inorganic materials and biological environments occurring at the nanoscale level are crucial to understand the mechanisms behind the bioactivity of biomaterials and for their better design. In the present study, we prepare TiO2 and TiO2/hydroxyapatite (HA) scaffolds for Tissue Engineering (TE) via a sol–gel/polymeric sponge method. The obtained architectures have a biomimetic morphology (trabecular bone) and an average pore dimension of 100 mm. Moreover, we introduce a versatile electrochemically assisted deposition method for non-conductive substrates that allows the formation of a stable coating on the pore walls of the scaffolds with the morphology and phase composition determined by SEM and DRIFTS. Both the materials properties are strictly correlated to the scaffold composition: pure TiO2 scaffolds are coated with amorphous calcium carbonate while onto TiO2/HA scaffolds we observe the growth of octacalcium phosphate nanocrystals. The bioactivity of the TiO2-based scaffolds is then predicted examining the apatite formation on their surface in simulated body fluid. The presence of apatite crystals is observed only for pure TiO2 scaffolds due to the transformation of amorphous calcium carbonate into crystalline biomimetic HA: a novel bio-inspired crystallization pathway toward the bioactivity of scaffold for TE.

Published
2011

24. Most recent results in hydrogen production from glycerol steam reforming

Author

Gallo, A., Dal Santo, V., and Pirovano, C.

Abstract

Here we report the most recent results in hydrogen production through glycerol steam reforming (SR). Glycerol is principally obtained as byproduct of biodiesel production and a glut in its market is expected in the next few years, rendering it an attractive renewable source for hydrogen production. On the contrary of the well known methane and ethanol steam reforming, glycerol SR is not yet so extensively studied and the matter is still quite open. We briefly discuss the general features of the reaction taking into account thermodynamic, mechanism, support role and promotion effects, giving some selected examples on non noble (Ni) and noble metals (Pt, Rh, Ru) based catalytic systems.

Published
2011

30. Hydrogen production by glycerol steam reforming

Author

Dal Santo, V., De Grandi, V., Gallo, A., Sordelli, L., and Psaro, R.

Subjects
STEAM REFORMING, CHEMICAL VAPOR DEPOSITION (CVD), RHODIUM NANOPARTICLES, HYDROGEN, GLYCEROL
Published
2008

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