Unité de Catalyse et de Chimie du Solide site Artois
Faculté des Sciences de Lens
PUBLICATIONS MARQUANTES 2022 :
- «Crystallinity and piezoelectric properties of spray-coated films of P(VDF70-TrFE30): effect of film thickness and spin-crossover nanofillers»
J-E. Angulo Cervera, M. Piedrahita-Bello, B. Martin, E. Dantras, L. Nicu, T. Leichlé, K. Dalla Francesca, A. Da Costa, A. Ferri, R. Desfeux, L. Salmon, G. Molnar and A. Bousseksou
J. Mater. Chem. C, 2022, 10, 8466-8473 - doi: 10.1039/D2TC01162J
|Spray coating the ferroelectric polymer P(VDF-TrFE) appears as an attractive approach for the fabrication of electromechanical transducers. However, it is important to elucidate how the crystallinity and associated piezoelectric properties depend on the coating thickness and additives. To this aim, we have spray-coated various substrates both with pure and nanocomposite films of the 70-30 % copolymer in a broad thickness range (200 nm – 30 µm). Using X-ray diffraction, differential scanning calorimetry, Raman spectroscopy and atomic force microscopy, we show that the obtained films are dense and homogeneous with ca. 50-60 % crystallinity, which consists of a majority polar β-phase, with slight alterations in the sub-micrometer thickness regime. Robust piezoelectricity and ferroelectricity are revealed at room temperature through both local hysteresis loops and lithography experiments using the piezoresponse force microscopy technique. After poling, the piezoelectric d33 coefficient displays values up to -19 and -11 pC/N for the pure copolymer and the composite, respectively. For a 33 vol% load of inorganic spin-crossover nanofiller, the switching properties are substantially improved and a coercive voltage <10 V is demonstrated for micrometric films. Overall, this approach appears as a promising way for the in-situ integration of high quality piezopolymer films into complex transducer geometries for sensing, actuating and energy harvesting purposes.
- «Interesterification of triglycerides with methyl acetate for biodiesel production using a cyclodextrin-derived SnO@γ-Al2O3 composite as heterogeneous catalyst»
C. Prestigiacomo, M. Biondo, A. Galia, E. Monflier, A. Ponchel, D. Prevost, O. Scialdone, S. Tilloy, R. Bleta
Fuel 321 (2022) 124026 - doi: 10.1016/j.fuel.2022.124026
|Particle morphology and surface properties of metal oxides are topics of great importance in the field of heterogeneous catalysis. Herein, we have developed a molecular-colloidal coassembly approach combined with an ultrasonic-assisted precipitation method to fabricate SnO@γ-Al2O3 composites with tuneable pore size and well-defined octahedral-shape crystal structure. The supramolecular assemblies formed between the randomly methylated β-cyclodextrin (RaMeβCD) and Pluronic F127 were employed as template to tailor the size and shape of γ-Al2O3 nanoparticles and direct their assembly almost exclusively on the surface of micrometer-sized SnO single crystals. Results revealed that the cooperative action of the supramolecular template and γ-Al2O3 nanoparticles may have a critical effect on the growth and orientation of SnO microcrystals and ultimately determine their catalytic performance in the interesterification of rapeseed oil with methyl acetate. The compartmentalized SnO@γ-Al2O3 structures could achieve fatty acid methyl esters (FAME) and triacetin (TA) yields of 33.5% and 1.5% respectively after 30 min at 210 °C, exceeding by 38% the FAME yield of the commercial catalyst.
- «Nanoscale electrical investigation of transparent conductive electrodes Based on silver nanowire network»
S. H. Pham, A. Ferri, A. Da Costa, M. M. Saj Mohan, V. D. Tran, D. C. Nguyen, P. Viville, R. Lazzaroni, R. Desfeux, P. Leclère
Adv Mater Interfaces 2022, 9, 2200019 - doi: 10.1002/admi.202200019
Article in cover
|Presently, metallic nanowires (NWs) are the most promising materials to fabricate flexible transparent electrodes as an alternative to indium tin oxide. Here, the high performance of transparent conductive electrodes (TCEs) based on silver nanowires (AgNWs) percolation networks is reported. With optimized experimental conditions for the deposition, the AgNWs result in low sheet resistance of 10 Ω sq−1 combined with a high optical transmittance of 92.6% at λ = 550 nm. This leads to a valuable figure of merit as compared to other TCEs. In this study, the nanoscale electrical properties of the AgNWs are measured via conductive atomic force microscopy to characterize the percolation network. The electrical resistivity value calculated for a single AgNW is found to be about 12.35 µΩ cm, while a nanoscale conductivity map over an AgNW network bridging two electrodes has revealed high levels of current within the network over a distance of more than 1000 µm. The favorable determined conductivity results along with the high optical properties of the AgNWs network strongly suggest that thin-film electrodes based on AgNWs will be a potential approach for future flexible electronic devices.
- « Unnatural cyclodextrins can be accessed from enzyme-mediated dynamic combinatorial libraries»
D. Larsen, M. Ferreira, S. Tilloy, E. Monflier, S.R. Beeren
Chem. Comm. 2022, 58, 2287-2290 - doi : 10.1039/D1CC06452E
This article is part of the themed collection: Chemical Communications HOT Articles 2022
|Dynamic systems of cyclodextrins (CDs) enabled by a native cyclodextrin glucanotransferase (CGTase) can incorporate unnatural glucopyranose-derived building blocks, expanding the applicability of enzyme-mediated dynamic combinatorial chemistry by using synthetically modified substrates. Starting dynamic combinatorial libraries from CDs with a single 6-modified glucopyranose results in a dynamic mixture of CDs containing several modified glucopyranoses. The relative concentrations of modified α, β or γ-CDs can be controlled by the addition of templates, providing a novel way to access modified CDs.
- « An unusual O2-/F- distribution in the new pyrochlore oxyfluorides: Na2B2O5F2 (B= Nb, Ta)»
E. Boivin, F. Pourpoint, S. Saitzek, P. Simon, P. Roussel, H. Kabbour
Chem. Comm., 2022, 58, 2391-2394 - doi: 10.1039/D1CC06760E
|Two new oxyfluorides with a pyrochlore-type structure, Na2Nb2O5F2 and Na2Ta2O5F2, have been obtained and for which the XRD crystallographic study coupled with 19F solid state NMR reveals an unusual O/F distribution. Both materials are n-type semiconductors exhibiting photoconductive properties.
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