Fonctionnalisation de surface par chimie douce en solution liquide. Nanoparticules métalliques (platine, or, argent) et revêtements TiO2

Structural, optical, and photocatalytic properties of sol-gel TiO2 films have been studied. A particular attention has been paid to the influence of platinum metal nanoparticles on the photocatalytic activity. In that view, several platinisation protocols have been prospected to disperse platinum particles through photochemistry routes at the surfaces of TiO2 films. It is shown how a suitable control of the size, amount, and dispersion of platinum particles, which in turn relies on optimized elaboration parameters, yields a photocatalytic activity enhancement by a factor 3 to 4 compared to non-platinized films. These studies have also evidenced an unusual magnetism of platinum nanoparticles formed through photochemistry routes, as well as the potential of these particles for (photo)-electrochemical applications. These photochemistry routes have also been extrapolated to the elaboration of gold and silver nanoparticles, whose potential for optical and plasmonic applications is discussed.Les propriétés structurales, optiques et photocatalytiques de revêtements sol-gel TiO2 ont été étudiées. Une importance particulière a été donnée à l'influence de nanoparticules métalliques de platine sur l'activité photocatalytique. Pour cela, plusieurs protocoles de platinisation par voie photochimique ont été prospectés afin de disperser des particules de platine à la surface des revêtements TiO2. Nous montrons comment un contrôle adapté de la taille, du taux et de la dispersion des particules de platine, lesquels relèvent de paramètres d'élaboration optimisés, conduit à une augmentation d'activité photocatalytique par un facteur 3 à 4 par rapport à des revêtements non platinisés. Ces études ont aussi mis en évidence le magnétisme inusuel des nanoparticules de platine formées par voie photochimique, ainsi que le potentiel de ces particules pour des applications (photo)-électrochimiques. Ces voies d'élaboration photochimiques ont également été extrapolées à la synthèse de nanoparticules d'or et d'argent dont le potentiel pour des applications en optique et plasmonique est discuté

Nouvelle génération de capteurs chimiques optiques opérant en milieu biologique

National audienc

Sol-Gel Direct Photolithography - Principle and Applications

International audienc

Sol-Gel Based Direct Photolitography : Principle and Applications

International audienc

Sol-Gel Based Direct Photolitography : Principle and Applications

International audienc

Surface Functionalization by Sol-Gel Chemistry

International audienc

From Superhydrophilic to Superhydrophobic Surfaces

International audienc

Nanostructuration de couches minces pour le développement de revêtements superhydrophobes et transparents

National audienc

Study and Optimization of a Micro-Structured Waveguiding and Fluorescent Sol-Gel Architecture

Channel waveguides with diffraction gratings at their input and output for light injection and extraction, respectively, constitute the key components for applications in integrated optics and photonics. Here, we report for the first time on such fluorescent micro-structured architecture entirely elaborated on glass by sol-gel processing. This architecture particularly takes advantage of a high-refractive index and transparent titanium oxide-based, sol-gel photoresist that can be imprinted through a single photolithography step. This resist enabled us to photo-imprint the input and output gratings on a photo-imprinted channel waveguide doped with a ruthenium complex fluorophore (Rudpp). In this paper, the elaboration conditions and optical characterizations of derived architectures are presented and discussed with respect to optical simulations. We firstly show how the optimization of a two-step deposition/insolation sol-gel procedure leads to reproducible and uniform grating/waveguide architectures elaborated on rather large dimensions. Then, we show how this reproducibility and uniformity govern the reliability of fluorescence measurements in waveguiding configuration. These measurements demonstrate that: (i) our sol-gel architecture is well adapted to the efficient channel–waveguide/diffraction grating coupling at the Rudpp excitation and emission wavelengths; (ii) it enables an efficient propagation of the emission signal in the core of the waveguide allowing its photo-detection after extraction through the output grating; and (iii) it is affected by very reduced parasitic mechanisms, such as propagation losses and photobleaching features. This work constitutes a promising preliminary step toward the integration of our architecture in a microfluidic platform for further fluorescence measurements in liquid medium and waveguiding configuration

The photocatalytic activity of sol-gel derived photo-platinized TiO2 films

Sol–gel TiO2 thin films have been loaded with platinum clusters through a photo-platinization method using water/ethanol platinum solutions. The morphological and physico-chemical properties of platinized films as well as the chemical state of platinum clusters have been studied by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. These characterizations show that morphological and physico-chemical properties are strongly influenced by the water/ethanol composition of the platinum solution and temperature of the post-platinization heat-treatment, which in turn determines the photocatalytic performances of platinized films. UV-assisted photocatalytic reactions induced by platinized films follow bi-regime kinetics. The first regime is characterized by a rather high rate constant, while long term UV exposition promotes a more or less pronounced deceleration of the photocatalytic reaction. Optimization of the photocatalytic activity requires a platinization in presence of a water excess followed by a heat-treatment in the 250–400 °C thermal range. Films processed in such conditions exhibit rate constants in the first and second photocatalysis regime which are four times and three times greater, respectively, than the rate constant measured for non-platinized films