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The effects of copper nanoparticles (CuNP) dispersion on the optical and electrical properties of mesoporous SBA-15 like silica were investigated. Full characterization of the resulting SBA-15-Cu through X-ray diffraction (XRD), thermogravimetry analysis (TGA), scanning electron microscopy (SEM), energy dispersion X-ray fluorescence (ED-XRF), diffuse reflectance (DRS) and Fourier Transform Infrared spectroscopy (FT-IR) revealed marked changes in the structure properties after copper incorporation. Slight decrease in the optical band gap energy in the SBA-15-Cu was also noticed. The shifts towards higher wavelengths are attributed to change in the acceptor capacity level induced by iron nanoparticles. Measurements of Z' and Z" in temperature showed an improvement in proton mobility of SBA-15-Cu. Deeper insights in the capacitance and conductance by impedance spectroscopy measurements over a wide range of frequencies at various temperatures suggest that CuNPs interaction with SBA-15 surface and silanol deprotonation can be, at least partly, responsible for conductance improvement. The above properties make these materials to be regarded as efficient materials for potential applications in electronics.

International audience; In this study, a flexible multifunctional fibrous membrane for heterogeneous Fenton-like removal of organic and pathogenic contaminants from wastewater was developed by immobilizing zerovalent iron nanoparticles (Fe-NPs) on an amine/thiol grafted polyester membrane. Full characterization of the resulting polyester membranes allowed validation of successful grafting of amine/thiol (NH 2 or SH) functional groups and immobilization of Fe-NPs (50-150 nm). The Fenton-like functionality of iron immobilized fibrous membranes (PET-Fe, PET-Si-NH 2-Fe, PET-NH 2-Fe, and PET-SH-Fe) in the presence of hydrogen peroxide (H 2 O 2) was comparatively studied in the removal of crystal violet dye (50 mg L À1). The effect of pH, amount of iron and H 2 O 2 concentration on dye removal was systematically investigated. The highest dye removal yield reached 98.87% in 22 min at a rate constant 0.1919 min À1 (R 2 ¼ 95.36) for PET-SH-Fe providing 78% toxicity reduction assessed by COD analysis. These membranes could be reused for up to seven repeated cycles. Kinetics and postulated mechanism of colour removal were proposed by examining the above results. In addition, the resultant membranes showed substantial antibacterial activity against pathogenic bacteria (Staphylococcus epidermidis, Escherichia coli) strains studied through disc diffusion-zone inhibitory and optical density analysis. These findings are of great importance because they provide a prospect of textile-based flexible catalysts in heterogeneous Fenton-like systems for environmental and green chemistry applications.

International audience; Polyester (PET) was pre-activated by atmospheric air plasma and coated by various inorganic oxide nanoparticles (MOx) such as titanium dioxide (TiO2), zinc oxide (ZnO), and silicon oxide (SiO2), using poly(vinylidene fluoride) (PVDF) and chitosan (CT) as binders. The resulting PET-PVDF-MOx-CT composites were thermally compressed and then characterized by scanning electron microscopy, Fourier infrared spectroscopy, thermal gravimetric analysis, and flame retardancy (FR) ability tests. PET modifications resulted in more thermally stable and less harmful composites with weaker hazardous gas release. This was explained in terms of structure compaction that blocks pyrolysis gas emissions. CT incorporation was found to reduce the material susceptibility to oxidation. This judicious procedure also allowed improving flame retardancy ability, by lengthening the combustion delay and slowing the flame propagation. Chitosan also turned out to contribute to a possible synergy with the other polymers present in the synthesized materials. These results provide valuable data that allow understanding the FR phenomena and envisaging low-cost high FR materials from biodegradable raw materials.

This study reports the synthesis, immobilization and stabilization of multiscale zero valent iron (Fe0 = ZVI) particles on fibrous polyester (PET) nonwoven membrane for heterogeneous Fenton-like removal of hazardous pollutants in water. Activation of PET fiber surface by air atmospheric plasma with or without a consecutive grafting of hyperbranched poly-(ethylene glycol)-pseudo generation 5 dendrimer having hydroxyl (-OH) end group functionality created polar reactive functional groups allowing immobilization and stabilization of ZVI particles. Synthesis of ZVI was carried out through chemical reduction of ferric ions, either through a single step in-situ, or a two-step ex-situ reduction-immobilization method. The nonwovens were characterized using wettability, Fourier transform infrared spectroscopy (FTIR), optical microscopy, scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA). Results confirmed the formation and immobilization of nano to sub-micronic multi-scale ZVI particles. The particle size, distribution and stability of ZVI were found to be influenced by the methods of ZVI synthesis and PET surface activation used. The ZVI particles initially formed, quasi-instantaneously turned to yellowish brown indicating the formation of oxide layer, except in the case of dendrimer grafted PET, where higher content (22.30%) and stability of ZVI was detected. All ZVI immobilized nonwovens exhibited high effectiveness towards Fenton-like degradation of malachite green dye (20 ppm), with fastest color removal (98% in 20 min) achieved by dendrimer/ex-situ nonwoven. This nonwoven could be used up to eight repeated cycles providing low TDS (52 ppm) and high COD reduction (66.23%). Combined use of eco-friendly plasma and dendrimer grafting, provides efficient fibrous textile base heterogeneous catalysis.

Robust immobilization of glucose oxidase (GOx) enzyme was achieved on poly(ethylene terephthalate) nonwoven fabric (PN) after integration of favourable surface functional groups through plasma treatments [atmospheric pressure-AP or cold remote plasma-CRP (N2 + O2)] and/or chemical grafting of hyperbranched dendrimers [poly-(ethylene glycol)-OH or poly-(amidoamine)]. Absorption, stability, catalytic behavior of immobilized enzymes and reusability of resultant fibrous bio-catalysts were comparatively studied. Full characterization of PN before and after respective modifications was carried out by various analytical, instrumental and arithmetic techniques. Results showed that modified polyester having amine terminal functional groups pledged better surface property providing up to 31% enzyme loading, and 81% active immobilized enzymes. The activity of the enzyme was measured in terms of interaction aptitude of GOx in a given time to produce hydrogen peroxide using colorimetric assay. The immobilized GOx retained 50% of its original activity after being reused six (06) times and exhibited improved stability compared with the free enzyme in relation to temperature. The reaction kinetics, loading efficiency, leaching, and reusability analysis of enzyme allowed drawing a parallel to the type of organic moiety integrated during GOx immobilization. In addition, resultant fibrous bio-catalysts showed substantial antibacterial activity against pathogenic bacteria strains (Staphylococcus epidermidis and Escherichia coli) in the presence of oxygen and glucose. These results are of great importance because they provide proof-of-concept for robust immobilization of enzymes on surface-modified fibrous polyester fabric for potential bio-industrial applications.

International audience; Mesoporous silica SBA-15 was functionalized with various amines and then doped with copper II cation (Cu2+). The modified materials were tested for the retention of CO2 at room temperature using temperature-programmed desorption (CO2-TPD). Several parameters affecting the CO2 retention capacity (CRC) such as the nature of amine groups, repetitive adsorption-desorption cycles and dispersion of copper were investigated. CO2-TPD and H2O-TPD allowed correlating the hydrophilic character with the CO2 retention capacity. The obtained results showed that amine-functionalized mesoporous materials containing their own moisture exhibit higher effectiveness in the retention of CO2. Triamine-functionalized SBA-15 displayed the highest CRC value as a result of the increase of the number of adsorption sites. Material reuse in three adsorption/desorption cycles revealed high stability with a slight decrease in CRC. The dispersion of copper induced a progressive decrease in the CRC value. The CRC decreased with increasing Cu2+ content due to competitive complexation of Cu2+ by the amino groups.

Intercalation of Na+-montmorillonite (NaMt) by dendrimer H20 and incorporation of palladium (Pd) and copper (Cu) nanoparticles (PdNP and CuNP) resulted in NaMt-H20-Cu and NaMt-H20-Pd materials with affinity towards carbon dioxide (CO2) and hydrogen (H2). Metal incorporation produced a slight structure compaction due to PdNP and CuNP interactions with clay lattice and dendrimer oxygen atoms. Measurements through CO2 temperature programmed desorption revealed higher CO2 retention capacity for NaMt-H20-Pd but higher hydrogen uptake for NaMt-H20-Cu. The affinity towards hydrogen decreased in the following sequence: NaMt-H20-Cu > NaMt-H20-Pd > NaMt-H20 > NaMt, confirming the significant role of the incorporated metals. Hydrogen was found to adsorb almost instantly at ambient temperature and pressure, with easy consecutive release upon slight heating up to 80 °C or under forced convection upon strong carrier gas stream. These results demonstrate the occurrence of preponderantly physical hydrogen adsorption, opening promising prospects for the reversible capture of CO2 and hydrogen.

The affinity towards carbon dioxide (CO2) of coal fly ash-derived zeolites such as 4A, NaP1, zeolite X nanosized and their commercial counterparts was investigated. For this purpose, their surface basicity and hydrophilic character were assessed through thermal programmed desorption measurements (TPD) of CO2 and water retention capacities (CRC and WRC, respectively). X-ray powder diffraction (XRD) and fluorescence (XRF), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and measurements on nitrogen adsorption-desorption isotherms demonstrated the key-roles of the zeolite structure and chemical composition. Decreasing CRC induces a WRC increase, indicating a direct proportionality between the zeolite basicity and hydrophobic character, which are essential requirements for potential applications in the capture of acidic gases. TPD patterns deconvolution revealed an enhancement of the hydrophilic character and weak to medium basicity with increasing Si content at the expense of strong basic sites. All zeolites display at least three strengths in retaining CO2 and moisture, whose distribution is governed by the structure and chemical composition. Within specific Si/Al range, the partial negative charge of lattice oxygens was found to strongly influence the zeolite basicity and hydrophobic character. These findings are of great interest, because they allow tailoring the surface properties for optimum and reversible capture of greenhouse gases, acidic gasses and volatile organic compounds.

This paper presents for the first time surface functionalization of cocoa shells (CS) through the covalent grafting of 3-aminopropyltriethoxysilane (APTES) followed by the substitution of poly(dimethylsiloxane) (PDMS) and in situ generation/insertion of cobalt nanoparticles (Co-NP). The immobilization and stability of APTES–PDMS on cocoa shell were confirmed by Fourier transform infrared spectroscopy and differential scanning calorimetry. Morphological analyses by scanning electron microscopy demonstrated that Co-NPs successfully grew on the surface of CS–APTES–PDMS. The CO2-adsorption capacity of these new materials was examined at ambient conditions. Both CS–APTES–PDMS and CS–APTES–PDMS–Co showed increased CO2 adsorption capacities as compared to unmodified cocoa shell. This enhancement was explained by the synergetic behavior of the silane derivate, PDMS grafting, and Co-NP incorporation for CO2 adsorption. This work represents a new step toward using cocoa shell as an excellent low-cost candidate for a variety of environmental applications such as CO2 storage at ambient temperature.

International audience; Dispersion of iron nanoparticles (Fe-NPs) was achieved on polyester fabrics (PET) before and after the incorporation of dendrimers (PAMAM), 3-(aminopropyl) triethoxysilane (APTES) or thioglycerol (SH). The catalytic activity of the resulting materials (PET-Fe, PET-PAMAM-Fe, PET-APTES-Fe and PET-SH-FE) was comparatively investigated in the degradation of 4-nitrophenol (4-NP) and methylene-blue (MB). Full characterization through diverse instrumental methods allowed correlating the type of the organic moiety incorporated with the Fe content, catalytic properties and stability. The highest 4-NP degradation yield reached 99.6% in 12 min for PET-SH-Fe. The catalytic activity was explained in terms of reactant interaction with Fe-NPs. The 1st order reaction kinetics and pseudo-1st order adsorption kinetics provide evidence of the key role of reactant adsorption. These findings allow envisaging the preparation of fiber-based catalysts for potential uses in environmental and green chemistry.

International audience; In this work, for the first time, a grafting of 3-aminopropyltriethoxysilane (APTES) followed by incorporation of iron nanoparticles (Fe-NPs) was used for the functionalization of graphene oxide (GO). Changes in stability, structural, morphological, thermal and catalytic properties of the resulting GO/APTES/Fe material were investigated by scanning electron microscopy, transmission electron microscopy, energy dispersive X-Ray, Fourier transform infrared and UV–visible spectroscopies, zeta potential measurements, X-ray photoelectron spectroscopy and differential scanning calorimetry. The average crystallite size of GO/APTES/Fe was found to decrease significantly after the post treatment, producing slight structure compaction. Iron nanoparticles were immobilized by APTES on the GO sheets, with a particle size around 50 nm. Fe insertion and APTES grafting resulted in high thermal stability of GO. As an application, GO/APTES/Fe exhibited an excellent catalytic activity in the reduction of 4-nitrophenol into 4-aminophenol. The presence of both APTES and small amount of Fe nanoparticles in GO/APTES/Fe induced a significant improvement in catalytic activity. GO/APTES/Fe also showed appreciable recyclability after four repeated uses without noticeable loss in activity. This stability was higher to those of other GO-materials. The results obtained herein open new prospects for Fe-loaded organo-graphene oxide as efficient material in catalysis and industrial applications.

This work focuses on the optimization of heterogeneous Fenton-like removal of organic pollutant (dye) from water using newly developed fibrous catalysts based on a full factorial experimental design. This study aims to approximate the feasibility of heterogeneous Fenton-like removal process and optionally make predictions from this approximation in a form of statistical modeling. The fibrous catalysts were prepared by dispersing zerovalent iron nanoparticles on polyester fabrics (PET) before and after incorporation of either polyamidoamine (PAMAM, –NH2) dendrimer, 3-(aminopropyl) triethoxysilane (APTES, –Si–NH2) or thioglycerol (SH). The individual effect of two main factors [pH (X1) and concentration of hydrogen peroxide-[H2O2]μl (X2)] and their interactional effects on the removal process was determined at 95% confidence level by an L27 design. The results indicated that increasing the pH over 5 decreases the dye removal efficiency whereas the rise in [H2O2]μl until equilibrium point increases it. The principal effect of the type of catalysts (PET–NH2–Fe, PET–Si–NH2–Fe, and PET–SH–Fe) did not show any statistical significance. The factorial experiments demonstrated the existence of a significant synergistic interaction effect between the pH and [H2O2]μl as expressed by the values of the coefficient of interactions and analysis of variance (ANOVA). Finally, the functionalization of the resultant fibrous catalysts was validated by electrokinetic and X-ray photoelectron spectroscopy analysis. The optimization made from this study are of great importance for rational design and scaling up of fibrous catalyst for green chemistry and environmental applications.

International audience; This work reports the design and functionalization of new composite-based polyethylene terephthalate (PET) fibers with high anti UV radiation. Polyethylene terephthalate fibrous nonwovens were coated by materials oxides (MOx) like titanium dioxide (TiO2), zinc oxide (ZnO) and silicon dioxide (SiO2). Chitosan (CT) and polyvinylidene fluoride (PVDF) polymers were used to ensure the good surface compatibility of the resulting composite PET-PVDF-MOx-CT. These composites were fully characterized and the chemical coatings, surface modification, physical and thermal properties were investigated. Incorporation of materials oxides resulted in the formation of strong cross-linked chitosan network. The developed modification on PET nonwovens allows to highly reducing the UV radiation with an excellent blocking rate and a good UV protection factor (80.5–113.4). An outline mechanism is proposed for the UV protection. This was explained by the surface compatibly and the interfacial bonding occurred in the matrix. Regarding to the above results, the current work developed a facile process for the production of advanced materials based nonwovens with excellent UV blocking.

International audience; This article reports the synthesis and functionalization of a novel CuO@SiO2-APTES@Ag0 core-shell-shell material using a simple and low-cost process. The growth, design strategies and synthesis approach are the key factors for the development of CuO@SiO2-APTES@Ag0 as efficient material with enhanced antibacterial activity. We investigated the morphology, surface charge, structure and stability of our new core-shell-shell by atomic force microscopy, scanning electron microscopy, energy dispersive X-ray, Fourier transform infrared and UV–visible spectroscopies, zeta potential measurements, and differential scanning calorimetry. The covalent surface grafting of APTES (3-(aminopropyl)triethoxysilane) onto CuO@SiO2 involving electrostatic interactions was confirmed. Size measurements and Scanning electron images showed that both APTES grafting and SiO2/Ag shells dropped on the surface of CuO produced structural compaction. UV–Vis spectroscopy proved to be a fast and convenient way to optically detect SiO2 shell on the surface of colloids. Additionally, the Ag-decorated CuO@SiO2-APTES surfaces were found to possess antibacterial activity and thermally more stable than undecorated surfaces. CuO@SiO2-APTES@Ag0 core-shell had antibacterial properties against Gram-positive bacteria making it a promising candidate for antibacterial applications.

Metal-organoclays (MOC) were prepared through incorporation of Boltorn polyol dendrimer H30 in Na+-exchanged montmorillonite (NaMt), followed by in-situ dispersion of Cu0 and Pd0 nanoparticles (CuNPs and PdNPs). The organoclays displayed high CO2 retention capacity (CRC) of 3.6–11.1 μmol/g, but metal incorporation induced a significant increase of hydrogen uptake up to 51.8–508.2 micmol/g at the expense of the CRC. Thermal programmed desorption and FT-IR investigations revealed strong interactions with CO2 before metal incorporation. These interactions markedly depleted in the presence of CuNPs and PdNPs. This was regarded as a precise indicator of the appreciable metal stabilization within the organic entanglement, due to enhancements of HO:Cu0 and HO:Pd0 interactions at the expense of HO:CO2 carbonate-like association. The CO2 and H2 retention capacities (CRC and HRC, respectively) were found to strongly correlate to the number of OH groups of the dendritic moiety incorporated. Hydrogen retention appears to involve mainly physical interactions as supported by easy gas release between 20 °C and 75 °C or even at room temperature under vacuum. This demonstrates unequivocally the reversible capture of hydrogen. The increase of the hydrogen uptake with increasing contact time provides evidence of the occurrence of diffusion phenomena. This was not observed with CO2 before metal incorporation, suggesting a structure compaction that improves metal stabilization. This opens new prospects for hydrogen storage via truly reversible capture on low cost clay materials and biodegradable hyperbranched macromolecules deriving from plants.

International audience; A facile and eco-friendly method was developed to prepare a microporous CuO@Ag0 core–shell with high catalytic and antibacterial activities. Scanning and transmission electron microscopy revealed a preponderance of nearly spherical 50 nm particles with slight structure compaction. Comparison of the hysteresis loops confirmed the structure compaction after AgNP incorporation, and a significant decrease of the specific surface area from 55.31 m2 g−1 for CuO to 8.03 m2 g−1 for CuO@Ag0 was noticed. A kinetic study of 4-nitrophenol (4-NP) reduction into 4-aminophenol (4-AP) with sodium borohydride revealed a first order reaction that produces total conversion in less than 18 minutes. CuO@Ag0 also exhibited appreciable antibacterial activity against Staphylococcus aureus. The antibacterial effects were found to strongly depend on the size, contact surface, morphology and chemical composition of the catalyst particles. The addition of Ag0-NPs produced more reactive oxygen species in the bacteria medium. These results open promising prospects for its potential applications as a low cost catalyst in wastewater treatment and antibacterial agent in cosmetics.

Nanoparticles of Cuo (CuNPs) and Feo (FeNPs) were dispersed in SBA-16-like silica, resulting metal-loaded materials (Cu-SBA-16 and Fe-SBA-16) with improved affinity towards hydrogen. Electron microscopy and X-ray diffraction showed that MNP dispersion occurs mainly inside SBA-16 channels. MNP incorporation was found to confer affinity to the silica surface, since higher CO2 retention capacity (CRC) was registered Cu/SBA-16 and Fe/SBA-16. This was accompanied by a significant improvement of the affinity towards hydrogen, as supported by hydrogen adsorption tests. This was explained in terms of strong hydrogen interaction with MNP and lattice oxygen atoms. The results reported herein open new prospects for SBA-16 as potential adsorbents for hydrogen storage.

Incorporation of iron nanoparticles (FeNP) induced changes in the textural and electrical properties of SBA-15-like silica. Electron microscopy showed that FeNP dispersion occurs mainly inside the channels. Diffuse UV–Vis reflectance spectroscopy revealed a band gap decrease from 2.68 eV to 2.59 eV. Nyquist plots ( Z ″ versus Z ′) were found to fit with an equivalent circuit model consisting of a resistance Rs , a double layer capacitance Q , an electron-transfer resistance R e t and a Warburg impedance Z w . FeNPs and silica deprotonation seem to be responsible of conductance change. SBA-15-Fe appears to be a promising material for electrodes and semi-conductors.

This study reports the carbon dioxide (CO 2 ) adsorption on montmorillonite (NaMt) incorporating Cu 0 , Fe 0 , Pd 0 and Ag 0 as metallic nanoparticles (MNPs). The changes in structural, textural, morphological and adsorption properties of the resulting materials (NaMt-MNPs) were investigated. Electron microscopy and X-ray diffraction showed that dispersion of fine MNPs occurs mainly within the interlayer space of NaMt, producing a slight structure expansion. This was accompanied by a visible enhancement of the affinity towards CO 2 , as supported by thermal programmed desorption measurements. NaMt-MNPs displayed high CO 2 retention capacity (CRC) of ca. 657 μmol/g for NaMt-Cu as compared to NaMt. This was explained in terms of increased number of available adsorption sites due to enlarged interlayer spaces caused by MNP insertion. The differences in CO 2 adsorption capacities clearly demonstrate the key role of MNPs in improving the surface properties and adsorption capacity. The results reported herein open new prospects for clay supported metal nanoparticles as efficient adsorbents for CO 2 .

Copper-loaded organo-montmorillonite showed improved affinity towards hydrogen under ambient conditions. Clay ion exchange with a propargyl-ended cation followed by thiol-yne coupling with thioglycerol resulted in a porous structure with a 6 fold higher specific surface area, which dramatically decreased after copper incorporation. X-ray diffraction and photoelectron spectrometry, nuclear magnetic resonance (1H and 13C) and CO2-thermal programmed desorption revealed strong sulfur:Cu0 and oxygen:Cu0 interactions. This was explained in terms of structure compaction that 'traps' Cu0 nanoparticles (CuNPs) and reduces their mobility. Transmission electron microscopy showed predominant 1.0-1.5 nm CuNPs. Hydrogen capture appears to involve predominantly physical interaction, since differential scanning calorimetry measurements gave low desorption heat and almost complete gas release between 20 °C and 75 °C. Possible hydrogen condensation within the compacted structure should hinder gas diffusion inside CuNPs and prevent chemisorption. These results allow safe hydrogen storage with easy gas release to be envisaged even at room temperature under vacuum. The reversible capture of hydrogen can be even more attractive when using natural inorganic supports and commercial plant-derived dendrimers judiciously functionalized, even at the expense of porosity.

International audience; In this work, polyester fiber (PET) were functionalized by oxides (Ox) like titanium dioxide (TiO2), zinc oxide (ZnO) and silicon dioxide (SiO2), using polyvinylidene fluoride (PVDF) as binder to obtain a PET-PVDF-Ox material. Chitosan polymer (CT) was further grafted as coating layer to improve the surface compatibility, resulting in the PET-PVDF-Ox-CT composite. The obtained products were thermally pressed and fully characterized. The chemical coatings, physical and thermal properties were investigated. It was found that coated PET nonwoven is highly hydrophobic materials with good diffusion resistance. Incorporation of TiO2, ZnO and SiO2 resulted in the formation of strong cross-linked CT network, producing improved dripping resistance of PET nonwoven. In addition, the modification steps allowed increasing significantly the mechanical resistance. This was explained in terms of improved surface compatibly and interfacial bonding occurred in the matrix. Moreover, soil release tests confirmed the high durability against washing for PET-PVDF-Ox-CT composite. This work allowed developing a facile process for the fabrication of new composite based nonwovens with satisfactory durability and high mechanical resistance.

International audience; A novel hydrochar-based core–shell material with improved affinity towards CO2 was synthesized through encapsulation within ZnO shell, followed by chemical grafting to an organic moiety bearing terminal diethanolamino groups and further dispersion of Cu0 nanoparticles. Characterization through nitrogen adsorption–desorption isotherms with BET and BJH models, SEM, TEM, zeta potential measurements, FTIR spectroscopy, DSC and XPS analyses revealed a strong influence of the modification procedure on the performance of each material in CO2 adsorption. The resulting metal-inorganic-organic-core–shell (MIOCS) displayed compacted structure with a wide pore size distribution that imposes intraparticle diffusion as a kinetic-controlling step. Cu-MIOCS showed an appreciable CO2 retention capacity of 5.42 mmol/g compared to many adsorbents reported so far. This affinity towards CO2 was explained in terms of physical and non-stoichiometric CO2 condensation. This finding is of great importance, because it demonstrates that judicious modifications of vegetal-deriving wastes such as woods and other biomasses give rise to added-value materials as low cost and efficient gas adsorbents with high affinity towards CO2.

Nitrate (NO3−) and chromium (Cr(VI)) ions from contaminated aqueous solutions were successfully adsorbed onto functionalized cocoa shell (ECAB, an agricultural waste material) via chemical grafting of 3-aminopropyltriethoxysilane (APTES). The resulting adsorbent – ECAB-APTES-HCl – was characterized by SEM, zeta potential, calorimetry, FTIR spectroscopy and point of zero charge. The adsorption parameters were investigated to optimize the removal of chromium and nitrate ions. The maximum removal efficiency stabilized at around 91–99 % for chromium and 58 % for nitrate, for an initial concentration of 50 mg.L−1 of the ions. The adsorption process fitted well with both Freundlich and Langmuir isotherms, and with the pseudo-second order model. Accordingly, adsorption onto ECAB-APTES-HCl involved both physisorption and chemisorption. Desorption studies demonstrated that 82 % of nitrate and 79.8 % of chromium were recovered in less than 2 h. These results open onto the possible removal of heavy metals from aqueous solutions in the absence of energy constraints, using low-cost biomass relevantly functionalized for high adsorption efficiency.

In this work, the sol–gel technique was carried out to prepare lithium doped ZnO materials with a controlled percentage (3–10 %). The changes in structural, optical and photocatalytic properties were investigated using X-ray powder diffraction, FT-IR spectroscopy, diffuse reflectance UV–visible and scanning/transmission electron microscope. X-ray diffraction showed that ZnO nanoparticles exhibit hexagonal wurtzite structure. The calculated average crystalline size increases from 30 nm of ZnO and 40 nm of ZnO–Li (10 %). The UV peaks positions of the modified samples shifted towards the longer wavelength compared to pure ZnO. The optical band gap of the samples was found to be 3.24 eV for ZnO–Li (3 %) and 3.28 eV for ZnO–Li (10 %), which proves the change in the acceptor level induced by the Li atoms. For the application, the evaluation of the photocatalytic activity is carried out using p-nitrophenol (p-NP) as a model of chemical pollutants. As result, Li doped ZnO materials displayed photocatalytic activity is less than pure ZnO, due to the Li atom that increases the recombination rate of electron–hole pairs, which decreases the photocatalytic activity.

The structural, optical and electrical properties of molybdenum nanoparticles (Mo-NPs)-loaded anatase TiO2 were investigated using x-ray diffraction, UV–Vis diffuse reflectance, and Fourier transform infrared and complex impedance spectroscopy. x-ray diffraction showed that Mo-NPs incorporation induced a decrease in particle size from 30 nm to 21 nm of TiO2 and TiO2-Mo, respectively, producing a slight structure expansion. Mo-NPs dispersion resulted in a slight decrease in the optical band gap energy from 3.85 eV to 3.51 eV. Slight shifts towards higher wavelengths were attributed to the change in the acceptor capacity level induced by Mo-NPs. In addition, the ac impedance studies show the effect of Mo-NPs incorporation that appeared to be responsible for conductance of enhancement. The conduction mechanism is based on space charge-limited current via deep levels with different energy positions in the band gap. The temperature dependence of electrical properties showed that both capacitance and conductance of TiO2-Mo samples increased with increasing temperature. At low frequency, the relaxation phenomenon is related to the surface effect. The results will be beneficial to further developing titanium dioxide photo-catalysts.

Mo/DAN/ZnO was successfully synthesized through ZnO impregnation in a 1,5-diaminonaphthalene (DAN) solution followed by a dispersion of molybdenum nanoparticles (MoNPs). The resulting material was characterized by X-ray powder diffractometry, transmission electron microscopy, UV-diffuse reflectance, FT-IR spectrophotometery and complex impedance spectroscopy. No changes in the hexagonal shape of the ZnO crystals were noticed after modifications, but slight decrease in the optical band gap energy of Mo/DAN/ZnO was registered after incorporation of MoNPs and DAN. The effects of the surface groups of Mo/DAN/ZnO and charge transfer were found to be almost proportional to the capacitance. Mo/DAN/ZnO also displayed higher affinity towards hydrogen as compared to DAN/ZnO and ZnO. Hydrogen was found to adsorb almost instantly at ambient temperature and pressure, but maximum uptakes can be achieved only after long saturation time. This was explained in terms of diffusion hindrance. The results obtained herein open new prospects for Mo-loaded metal oxide as low cost electrode material and hydrogen storage matrice.

Iron nanoparticles were incorporated into zinc oxide powders by an in situ dispersion method. The products were fully characterized by X-ray diffractometry, diffuse reflectance, FTIR spectrophotometry and complex impedance spectroscopy. The XRD patterns agreed with that of the ZnO typical wurtzite structure, the sharp diffraction peaks indicating good crystallinity of ZnO and ZnO-Fe nanoparticles. The average particle size determined by the Scherrer equation showed an increase from 20 to 25 nm for ZnO and ZnO-Fe respectively. The UV peak positions of the modified samples shifted to a longer wavelength compared to pure ZnO, providing evidence of changes in the acceptor level induced by iron nanoparticles. The optical band gap of the samples was found to be 3.14 eV for ZnO and 3.04 eV for ZnO-Fe. The electrical properties were investigated between 273 and 413 K, at several frequencies. Besides, a detailed analysis of the impedance spectrum showed an appreciable improvement of the conductivity due to the addition of iron nanoparticles. The incorporation of Fe-NPs appears to be responsible for conductance variations, charge transfer and capacitance improvement. The above properties make these materials to be regarded as very promising electrode materials for high-efficiency energy storage.

Tin oxide (SnO 2 ) was functionalized by hexamethylenediamine (HMD) grafting and incorporation of iron nanoparticles (Fe-NPs) and, then, fully characterized by X-ray diffractometry, transmission electron microscopy, diffuse reflectance spectrometry, FTIR spectrophotometery, photoluminescence spectroscopy and complexes impedance spectroscopy measurements. The covalent surface-grafting of HMD within mesopores was confirmed by the results from Fourier-transformed infrared spectroscopy. XRD and TEM study showed a dominant tetragonal structure. Fe-NPs were finely dispersed inside mesopores, producing a slight structure compaction. The crystallite size decreased in the presence of HMD and Fe-NPs. Photoluminescence (PL) insights revealed the presence of oxygen vacancies and the PL intensity was found to strongly depend on HMD grafting and Fe-NPs insertion. The incorporation of both Fe-NPs and HMD grafting appear to be responsible for electrical properties improvement. This material displayed an unprecedented surface affinity factor towards hydrogen of 8.5 μmol m −2 at ambient temperature and pressure. This was attributed to the contribution of both physical and chemical hydrogen adsorption, and to the presence of fine Fe-NPs. These properties open promising prospects for green energy storage.

This study reports the modification of synthetic ZnO nanoparticles by Hexamethylemediamine (HMD) grafting and an in-situ dispersion of iron nanoparticles (FeoNPs). The changes in structural, optical and electrical properties of the resulting Metal-Organo-Zinc oxide (MOZ) were investigated. Covalent surface-grafting of HMD within ZnO mesopores was confirmed by Fourier-transformed infrared (FTIR) spectroscopy. Electron microscopy and X-ray diffraction showed that dispersion of fine iron NPs occurs mainly inside ZnO mesopores, producing a slight structure expansion. This was accompanied by a significant improvement of the electrical conductivity. Iron NP incorporation and HMD grafting resulted in a slight decrease in the optical band gap energy in the metal-organo-zinc oxide. Slight shifts towards higher wavelengths are attributed to change in the acceptor capacity level induced by iron nanoparticles. The capacitance, conductance and relaxation phenomenon of the material were studied by means of impedance spectroscopy measurements at several temperatures. Both FeoNPs incorporation and HMD grafting appear to be, at least partly, responsible for conductance variations. The effects of the surface groups of ZnO–HMD–Fe and charge transfer were found to be almost proportional to the capacitance. These properties make these materials to be regarded as promising electrode materials for high-efficiency energy storage.

International audience; Several iron oxides nanoparticles (Fe2O3@Fe2O3, Fe°@Fe2O3, GO@Fe2O3 and calcinated Fe2O3) have been assessed as catalysts in the 1,4-addition of a cyclic β-ketoester onto methyl vinyl ketone under neat conditions. It appeared that calcinated Fe2O3NP are efficient catalysts at 1 mol% loading for the Michael addition of 1,3-dicarbonyl compounds onto various enones.

Effective adsorbents for the reversible capture of CO2 at ambient temperature were prepared by acid activation of bentonite (AAB) and chemical grafting of 3-amino-propyltriethoxysilane (γ-APTES) or 3-diethanolamino-propyltriethoxysilane (3-diEtOH-APTES). Full characterization of the resulting organo-AAB materials through X-ray diffraction, nitrogen adsorption-desorption isotherms, thermogravimetric analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and 29Si solid-state nuclear magnetic resonance (NMR) revealed thermally stable porous structures with higher affinity towards CO2. Thermal programmed desorption analyses (TPD) gave appreciable CO2 retention capacity (CRC) with easy release of ca. 90% of the absorbed CO2 at temperature not exceeding 80 °C. Total regeneration of adsorbents was achieved at less than 160 °C, without affecting the stability of the grafted groups. Acid activation produced an increase of the number of silanol groups and of the silylation capacity, but unavoidably a marked CRC decay. Further grafting of amino and diethanol-amino groups was found to revive the affinity towards CO2. The CRC increase with increasing amount of impregnating CO2 and decreasing carrier gas throughput allows predicting even much higher CO2 uptakes than those obtained in the present work through predominant non-stoichiometric physical condensation around the amino groups. Such low-cost hybrid materials appear as promising alternative to others prepared by physical incorporation of amine, and the results obtained herein allow envisaging effective reversible capture of CO2 without amine loss upon thermal stresses.

Highlights• Reversible CO2 capture is possible on Co-loaded amino-functionalized hydrochar.• Co incorporation reduces the surface basicity of amino-functionalized hydrochar.• Co loading favors structure compaction and impedes direct CO2:NH2 interaction.• Weak non-contact CO2:NH2 interaction is favored at the expense of chemisorption.• Reversible CO2 capture is due to predominant physical condensation via weak interactions.; International audience; This work was achieved to investigate the effect of both aminopropyltriethoxysilane (APTES) grafting and cobalt particle incorporation on the CO2 adsorption behavior of cocoa shell based hydrochar (HC). Electron microscopy and measurements using nitrogen adsorption-desorption isotherms showed a structure swelling after APTES grafting, followed by a compaction after Co particle insertion that attenuates the surface basicity. HC-APTES-Co displayed higher CO2 retention capacity than its metal-free counterpart, in spite of its lower basicity and porosity. CO2 adsorption was found to obey pseudo-first order kinetics and intra-particle diffusion mechanisms due to the predominance of physical interaction. This favors CO2 condensation of higher CO2 amount than predicted by the stoichiometry of carbamate formation. This concept allows envisaging promising prospects for plant-deriving adsorbents intended for CO2 concentration and valorization into added values products.Graphical abstractChemical modification of hydrochar to obtain a robust and low cost material for CO2 uptake.

International audience; The aim of this research is to investigate how (3-aminopropyl)triethoxysilane (APTES) grafting and cobalt nanoparticles (Co-NPs) immobilization may improve the activity of cocoa shell (CS) towards the adsorption of CO2 under ambient temperature. Pure CS are agricultural by-products which are inexpensive and abundantly available. CS powder was functionalized at 80 °C by APTES grafting and modified through the subsequent immobilization of Co-NPs. Physical and thermal properties and stability of the adsorbents have been investigated. Thus, their composition, surface charge, and morphology were determined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), differential scanning calorimetry (DSC), and zeta potential measurements. CO2 adsorption capacity was remarkably increased from 0.015 mmol g−1 for the raw material to 0.24 mmol g−1 after surface modification, highlighting a promising synergistic effect. The adsorption behavior of CO2 was investigated, which involves both physical and chemical adsorption. We hope that this work will open new prospects to develop high-performance biomass-derived adsorbents.

International audience; A novel functional polyester fabric (PF) was successfully prepared by a facile method. PF were coated by copper oxide (CuO) followed by chemical grafting of 3-chloropropyltriethoxysilane (ClPTES) and diethanolamine (DEA). The morphology and structure of the resulting material PF@CuO–Si–N(OH)2 was characterized by X-ray diffraction, scanning electron and optical microscopy, thermogravimetry and Fourier-transformed infrared spectroscopy. The results revealed that the CuO particles were densely surrounded PF, and the covalent surface-grafting of ClPTES and DEA within PF was confirmed. It was also demonstrated that CuO/ClPTES/DEA addition generated new functional sites at the PF surface, improving the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The prepared PF@CuO–Si–N(OH)2 exhibited high catalytic activity with appreciable cycling stability for the reduction of 4-NP to 4-AP, even after six successive cycles with nearly 90% conversion. Hence, it may be conclude that the catalytic activity and stability of this catalyst allows envisaging great prospect for large scale reduction of 4-NP.

International audience; In this paper, a new synthetic strategy towards functionalized ZnO-HMD@ZnO-Fe/Cu core-shell using sol-gel process modified by chemical grafting of hexamethylenediamine (HMD) on the core and in-situ dispersion of Cu0/Fe0 as metallic nanoparticles (M-NPs) on the shell. The as-prepared core-shell materials were fully characterized by transmission electron microscopy, X-ray powder diffractometry, diffuse reflectance and FT-IR spectrophotometery, photoluminescence, and complexes impedance spectroscopy measurements. The XRD patterns agreed with that of the ZnO typical wurtzite structure, indicating good crystallinity of ZnO-HMD@ZnO-Fe/Cu, with the presence of Fe0 and Cu0 phases. Hexamethylenediamine grafting and M-NPs insertion were highly activated and enhanced the core and shell interface by the physiochemical interaction. After functionalization, luminescence intensities and electrical properties of both core and core-shell nanoparticles are improved, indicating the effects of the surface groups on the charge transfer of ZnO-HMD@ZnO-Fe/Cu. The hydrogen capacity retention was depended strongly on the composition and structure of the obtained core-shell. Iron/Copper-loaded ZnO-HMD@ZnO materials exhibited the highest capacity for hydrogen storage. The excellent stability and performance of the ZnO-HMD@ZnO-Fe/Cu core-shell make it an efficient candidate for hydrogen storage.

International audience; The outer portion of the cocoa bean, also known as cocoa husk or cocoa shell (CS), is an agrowaste material from the cocoa industry. Even though raw CS is used as food additive, garden mulch, and soil conditioner or even burnt for fuel, this biomass material has hardly ever been investigated for further modification. This article proposes a strategy of chemical modification of cocoa shell to add value to this natural material. The study investigates the grafting of aryl diazonium salt on cocoa shell. Different diazonium salts were grafted on the shell surface and characterized by infrared spectroscopy and scanning electronic microscopy imaging. Strategies were developed to demonstrate the spontaneous grafting of aryl diazonium salt on cocoa shell and to elucidate that lignin is mainly involved in immobilizing the phenyl layer.

International audience; A core-shell material was prepared using SBA-15 crystallites as cores for the growth of a ZnO shell, followed by Cu0 dispersion. The resulting Cu/SBA-15@ZnO nanostructure displayed higher specific surface area (SSA) and higher number of smaller pores as compared to the starting materials. Dispersion of fine Cu0NPs induced a compaction of the host matrice and a marked decay of the hydrophilic character, explained in terms of the involvement of terminal hydroxyl groups in competitive HO:Cu interaction at the expense of H-bridges with water. Heating at 400–450 °C seems to trigger ZnO dehydroxylation with possible self-polycondensation and/or the formation of Si-O-Zn bridges. This is an additional explanation of the significant SSA increase and decrease in the average pore diameter. Both ZnO and Cu0NP incorporation induced shifts in the UV–vis absorption band towards higher wavelengths, indicating a decrease in the optical band gap energy and an improvement of the conductance properties. As compared to ZnO, Cu0NPs produced stronger improvement of the conductance, which was found to increase with higher frequencies. Cu/SBA-15@ZnO also displayed higher affinity towards hydrogen as compared to SBA-15@ZnO and SBA-15 at ambient conditions. These outstanding properties combined to an appreciable thermal stability are worth to be prone to deeper investigations, because they can open promising prospects for Cu/SBA-15@ZnO as sensor, electrode material, electrocatalyst and/or hydrogen capture matrice.

International audience; Tantalum-decorated mixed oxides (Ti0.5Sn0.5O2) was successfully synthesized, using a microwave-assisted polyol process (MAP) and triethylene glycol as a solvent, in a much shorter time than conventional heating. The newly-synthesized nanocomposites materials were used to make resistive semiconductor gas sensors to detect CO2. The powders were investigated using X-ray diffractometry, transmission electron microscopy and N2 physisorption. The X-ray diffraction patterns of the samples confirm that TiO2 is in the anatase phase and SnO2 and Ti0.5Sn0.5O2 are in the cassiterite phase. The TEM images showed uniform isotropic morphologies with average sizes close to 10 nm. The optimized sensor, based on TiO2/SnO2/Ta showed promising performances towards CO2 capture, ensuring a high response and fast dynamics at an operating temperature of 20 °C. The CO2 adsorption capacity was also remarkably increased from 0.58 mmol g−1 for TiO2 alone to 0.90 mmol g−1 for the Ti0.5Sn0.5O2. This work brings insights into a new way of limiting atmospheric pollution using mixed-oxide nanoparticles.

International audience; Tin oxide (SnO2) was synthesized via a co-precipitation method and activated by 1,5 diaminonaphthalene (DAN) grafting and molybdenum nanoparticles (Mo-NPs) incorporation. The resulting SnO2–DAN–Mo nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, diffuse reflectance and FTIR spectrophotometry, photoluminescence spectroscopy and complex impedance spectroscopy measurements. The surface-grafting of DAN within mesopores was confirmed by Fourier-transform infrared spectroscopy. The XRD and TEM studies showed a dominant tetragonal structure. The dispersion of fine Mo-NPs on the surface of the matrices, produced slight structural compaction. The crystallite size decreased with the insertion of DAN and Mo-NPs. The photoluminescence study revealed the presence of oxygen vacancies and that the PL intensity strongly depends on DAN grafting and Mo-NPs insertion. In addition, both the incorporation of Mo-NPs and DAN grafting appear to be responsible for the changes in the conductance and relaxation phenomenon. The effects of surface groups of SnO2–DAN–Mo and charge transfer were found to be almost proportional to the capacitance. The above properties make these nanocomposites efficient electrode materials for green energy storage.