Unité de Catalyse et de Chimie du Solide site Artois
Faculté des Sciences de Lens
PUBLICATIONS MARQUANTES 2023 :
- «Application of cyclodextrins as second-sphere coordination ligands for gold recovery»
A. Ponchel, E. Monflier
Nat. Commun. 2023 14, 1283 - doi: 10.1038/s41467-023-36700-z
|Supramolecular chemistry based on cyclodextrin receptors as second-sphere ligands contribute to developing non-covalent materials with synergistic functionalities. Herein, we comment on a recent investigation of this concept, describing selective gold recovery through a hierarchical host-guest assembly specifically built from β-CD.
- «Exploiting poly(e-caprolactone) grafted from hydrohydroxymethylated sunflower oil as biodegradable coating material of water-soluble fertilizers»
A. El Mouat, T. El Assimi, M. Raihane, J. Ternel, H. Bricout, E. Monflier, S. Tilloy, M. Lahcini
Progress in Organic Coatings 179 (2023) 107513 - doi: 10.1016/j.porgcoat.2023.107513
|In the present study, hyperbranched poly(ε-caprolactones) were prepared and used as coating materials to prepare slow release diammonium phosphate (DAP) fertilizer. Firstly, the sunflower oil was hydrohydroxymethylated by one-pot two-step process using Rh(acac)(CO)2 as catalyst, and triethylamine as ligand. Next, the bio-based hyperbranched poly(ɛ-caprolactone) (PCL) were prepared in open air by in-situ ring-opening polymerization of ε-caprolactone using hydrohydroxymethylated sunflower oil as macro-initiator and tetra(phenylethynyl)tin (Sn(C ≡ CPh)4) as catalyst. The structures of the prepared polymers (SFO-O-g-PCL) were confirmed by nuclear magnetic resonance (1H NMR) and the infrared spectroscopy (FTIR). Furthermore, molecular weight values around 20.000 g.mol−1 of PCL grafted in SFO-O-g-PCL were obtained, the thermal stability and morphology of the coated film were also evaluated using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) respectively. The hydrophobic character of the films prepared from SFO-O-g-PCL was confirmed by measuring the contact angle of water droplets. In the second part, the DAP granular fertilizers were uniformly coated by the prepared material (SFO-O-g-PCL) using a laboratory rotary drum. Then the slow release performance in water of the coated and uncoated DAP fertilizer granules was evaluated by tracking the cumulative concentration of P2O5 released. Thus, it was found that only 10 % of P2O5 was released after 2 h of essay from the coated DAP compared to a total release of P2O5 from uncoated DAP (conventional fertilizer) during the same period. This finding opens a wide perspective to combine the advantages of hydrophobic polyesters and bio-based oils to produce biodegradable coating agents.
- «Effect of Sr and Ti substitutions on optical and photocatalytic properties of Bi1-xSrxFe1-xTixO3nanomaterials»
M. Benyoussef, S. Saitzek, N. S. Rajput, M. El Marssi, M. Jouiad
NANOSCALE ADV, 2023, 5, 869-878 - doi: 10.1039/D2NA00755J
|The potential use of down-sized BFO-xSTO systems (x ≤ 25%) as highly efficient photoanodes for photocatalytic water splitting is investigated. BFO-xSTO is prepared by a solid-state method and subsequently deposited by spray coating. The compounds possess rhombohedral symmetry for x ≤ 15% and phase coexistence for x > 15%, as demonstrated by Raman spectroscopy and transmission electron microscopy. Our findings revealed a drastic grain size decrease with increasing STO content, namely 260 nm for BFO to 50 nm for BFO with 25% STO. Moreover, BFO-xSTO, x > 10% exhibited high optical absorption (> 80%) in the full spectrum and interestingly a very promising band alignment with water redox potentials. Moreover, the photochemical measurements revealed a photocurrent density of ~0.17 μA cm−2 achieved for x = 15% at 0 bias. Using DFT calculations, the substitution effects on the electronic, optical, and photocatalytic performances of the BFO system were investigated and quantified. Surprisingly, a high hydrogen yield (~191 μmol g−1) was achieved by BFO-12.5%STO compared to 1 μmol g−1 and 57 μmol g−1 for BFO and STO, respectively. This result highlights the beneficial effects of both the downsizing and substitution of BFO on the photocatalytic water splitting and hydrogen production performances of Bi1−xSrxFe1−xTixO3 systems.
- «New Pyrochlore-like Oxyfluorides Na2-2xSnxM2O5F2 (M = Nb5+ or Ta5+ and 1 ≤ x ≤ 0) as Potential Candidates for Overall Water Splitting Photocatalysis»
E. Boivin, S. Saitzek, F. Fauth, M. Huvé, P. Roussel, H. Kabbour
Chem. Mater., 2023, 35, 2, 447–456 - doi: 10.1021/acs.chemmater.2c02801
|Lone pair containing oxyfluorides have recently emerged as efficient and stable photocatalysts for overall water splitting (OWS). In this work we have obtained several new potential OWS photocatalysts with pyrochlore structure (i.e., Na2–2xSnxM2O5F2 with M = Nb5+ or Ta5+ and 1 ≤ x ≤ 0) through kinetically controlled ion-exchange reaction from Na2M2O5F2. Rietveld refinement of the structures as well as DFT indicate the Sn2+ lone pair stereochemical activity. The partial density of states reveals contributions at the top of the valence band that are mainly composed of a Sn 5s–Sn 5p hybridization through the (O,F) 2p orbitals. This leads to a significant narrowing of the band gap and an improvement of the photoconduction response by a factor ca. 50 with respect to the x = 0 compound, Na2Nb2O5F2. The Mott–Schottky measurements show that all materials possess band edge positions encompassing the thermodynamic redox potential of H+/H2 and O2/H2O. However, the valence band of SnNb2O5F2 may not be oxidative enough to overcome the overpotential associated with the O2– oxidation and hence could be unsuitable for OWS photocatalysis in contrast with Na1.5Sn0.25Nb2O5F2.
- «Direct conversion of glucose to 5-hydroxymethylfurfural over niobium oxide/phosphate-carbon composites derived from hydrothermal carbonization of cyclodextrins»
W. H. Saadaoui, C. Machut, S. Rio, S. Bigot, V. Wiatz, E. Monflier, A. Ponchel
Molecular Catalysis - 537 (2023) 112931 - doi : 10.1016/j.mcat.2023.112931
|Direct conversion of glucose to 5-hydroxymethylfurfural was studied in a biphasic system, with phosphated niobium oxide-carbon catalysts. We developed a facile approach to generate Nb-based composites with high metal loadings (~20 %) through hydrothermal carbonization (HTC), followed by calcination and H3PO4 adsorption. Attention has been paid to the nature of oligosaccharide and amount of water used upon HTC. Catalysts were characterized by XRD, N2 adsorption, NH3-TPD, SEM-EDS and XPS. NbP@C-RB30 and NbP@C-RB15 prepared from randomly methylated ß-CD in low volumes were found to be more efficient for HMF production, with yields of 32-34 % attained after 3 h in biphasic NaCl-water/methyl isobutyl ketone media. Notably, HTC route provided appropriate conditions for forming acidic Nb2O5 nanoparticles, dispersed and maintained over carbon microspheres, and enriched with surface P–OH. These features played an important role for an adequate distribution of the catalyst in the reaction medium composed of two immiscible solvents.
- «Beneficial Effect of β-Cyclodextrin Assisted Synthesis of CuO/Hydroxyapatite Catalyst in Toluene Oxidation»
M. Ibrahim, M. Labaki, A. Ponchel, J-M. Giraudon, O. Gardoll, J-F. Lamonier
ChemCatChem 2023, 15, e202200943 - doi : 10.1002/cctc.202200943
|Two hydroxyapatite supported CuO (10 wt% Cu) catalysts were prepared using the wet impregnation method via the conventional process and with the addition of native β-cyclodextrin using Cu(NO3)2.3H2O as copper precursor and adopting a ratio of β-cyclodextrin to copper of 0.1. After the impregnation step, the materials were dried at 80 °C and calcined in flowing dry air at 400 °C. The copper supported materials were characterized in the dried state and after calcination by means of conventional methods including X-ray diffraction, TG-MS, H2-TPR-MS, Raman spectroscopy, UV-vis-DR, ToF-SIMS and XPS. It was found that β-cyclodextrin hasd a profound impact on the final properties of the catalysts, both in terms of reducibility and dispersion of active species. It is suggested that at the early stages of the calcination, some hydroxyl groups of the β-CD units in close contact with Ca2+ of hydroxyapatite could play the role of spacers between the copper-based entities thus minimizing the aggregation process of the CuO nanoparticles. Finally, these copper oxide catalysts prepared from β-cyclodextrin were able to oxidize toluene more efficiently than the conventional catalyst. The copper oxide particles generated by the thermal decomposition of Cu2(OH)3(NO3) were smaller than those formed with copper nitrate alone and exhibited a higher reducibility, two key determinants for VOC total oxidation on transition metal oxides.
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