References of "Mahy, Julien"
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See detailNi-doped γ-Al2O3 as secondary catalyst for bio-syngas purification: influence of Ni loading, catalyst preparation and gas composition on catalytic activity
Claude, Vincent; Mahy, Julien ULiege; Geens, Jérémy ULiege et al

in Materials Today Chemistry (2019), 13

In this work, Ni/γ-Al2O3 catalysts were prepared by sol-gel methods with different Ni loadings (10 to 50 wt.%) and used as secondary catalyst for the steam reforming of toluene. A sample prepared by wet ... [more ▼]

In this work, Ni/γ-Al2O3 catalysts were prepared by sol-gel methods with different Ni loadings (10 to 50 wt.%) and used as secondary catalyst for the steam reforming of toluene. A sample prepared by wet impregnation with 10 wt.% of Ni was also synthesized and compared to the corresponding sol-gel sample. This study was divided in three main parts: the comparison of catalysts prepared by sol-gel process and impregnation, the influence of the gas composition on the catalytic performance of the sol-gel 10 wt.% Ni/γ-Al2O3 catalyst and the influence of Ni loading on the catalytic activity. When sol-gel and impregnated samples are compared, the impregnated catalyst showed a high initial toluene conversion followed by a consequent and progressive deactivation. Contrarily, the sol-gel catalyst showed a stable catalytic activity and relatively low carbon deposit. Indeed, before the steam reforming of toluene at 650 °C, the sol-gel catalyst was only calcined and no reduction step was realized to reduce nickel oxide. So this sample was reduced during the catalytic test at 650 °C. Moreover, it was observed that, if toluene was withdrawn from the syngas mixture during the catalytic test, the sol-gel sample was progressively re-oxidized by CO2 and H2O, leading to higher deactivation. As the Ni loading increased, the nickel oxide with strong interactions (NiAl2O4) was progressively joined by nickel oxide with low interactions (NiO/Al2O3) and bulk nickel oxide (NiO). This led to a high initial conversion of toluene, but also to a progressive loss of the catalytic activity throughout the catalytic test. It was shown that the sol-gel method developed throughout this work allowed preparing micro/mesoporous Ni/γ-Al2O3 catalysts with a high dispersion of Ni nanoparticles. [less ▲]

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See detailOptimization of Synthesis Parameters for the Production of Biphasic Calcium Phosphate Ceramics via Wet Precipitation and Sol‐Gel Process
Tilkin, Rémi ULiege; Mahy, Julien ULiege; Regibeau, Nicolas ULiege et al

in ChemistrySelect (2019), 4(21), 6634-6641

During the past few years, bioceramics, like hydroxyapatite and β‐tricalcium phosphate have been widely developed for bone reconstruction. These materials have to meet strict criteria regarding ... [more ▼]

During the past few years, bioceramics, like hydroxyapatite and β‐tricalcium phosphate have been widely developed for bone reconstruction. These materials have to meet strict criteria regarding biocompatibility, degradability, and mechanical properties. This work has been focusing on the influence of synthesis parameters on the production of calcium phosphate mixes, called biphasic calcium phosphate. In this optic, powders obtained from two synthesis processes (i. e. wet precipitation and sol‐gel process) were produced. The influence of pH, Ca/P molar mixing ratio, and calcination temperature was studied. These new materials were characterized in terms of composition, thermal properties, and textural properties via X‐ray diffraction, infrared spectroscopy, scanning electronic microscopy, thermogravimetric analysis, and nitrogen adsorption‐desorption. Wet precipitation technique produces in situ mixes with different hydroxyapatite contents while the sol‐gel process ends up with ceramics contaminated by cytotoxic CaO. Wet precipitation has been demonstrated more successful to control in situ mixes with specific composition. [less ▲]

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See detailHydrodechlorination and complete degradation of chlorinated compounds with the coupled action of Pd/SiO2 and Fe/SiO2 catalysts: towards industrial catalyst synthesis conditions
Mahy, Julien ULiege; Tasseroul, Ludivine; Tromme, Olivier et al

in Journal of Environmental Chemical Engineering (2019), 7(1),

In this study, Pd/SiO2 and Fe/SiO2 catalysts have been synthesized by the cogelation process for hydrodechlorination applications. Different synthesis conditions were tested to approach the industrial ... [more ▼]

In this study, Pd/SiO2 and Fe/SiO2 catalysts have been synthesized by the cogelation process for hydrodechlorination applications. Different synthesis conditions were tested to approach the industrial conditions using industrial grade reactants and ambient air drying. The influence of these changes have been studied on the texture and the catalytic activity of the catalysts. The resulting materials are composed of metallic (Pd catalysts) or metallic oxide (Fe catalysts) nanoparticles highly dispersed in porous silica. The catalysts present a high specific surface area (between 250 and 500 m2/g) with a large pore size range between micro-, meso- and macropores. The modifications of the synthesis conditions give catalysts with similar textural properties compared to lab-scale catalysts. The catalytic activity of the binary catalysts have been evaluated on the hydrodechlorination of the 2,4,6-trichlorophenol (TCP) in water. Results show that Pd/SiO2 catalysts are able to dechlorinate the TCP and that Fe/SiO2 materials are able to degrade the resulting phenol. So this process allows a complete degradation of TCP. Industrial conditions catalysts show also similar catalytic results compared to lab-scale catalysts for the hydrodechlorination of the 2,4,6-trichlorophenol (TCP) in water. [less ▲]

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See detailPorphyrin-based hybrid silica-titania as a visible-light photocatalyst
Mahy, Julien ULiege; Pàez Martinez, Carlos ULiege; Carcel, Carole et al

in Journal of Photochemistry and Photobiology A: Chemistry (2019), 373

A silylated porphyrin derivative is co-hydrolyzed with Ti(OiPr)4 to produce a hybrid TiO2 photocatalyst, and three different ratios between porphyrin and TiO2 are made. In this way, the porphyrin ... [more ▼]

A silylated porphyrin derivative is co-hydrolyzed with Ti(OiPr)4 to produce a hybrid TiO2 photocatalyst, and three different ratios between porphyrin and TiO2 are made. In this way, the porphyrin fragments are held in the resulting matrix through strong Si-O-Ti covalent bonds to limit porphyrin leaching. Thanks to its photoactive character the porphyrin fragment can act as an actuator for the TiO2 to degrade organic pollutants using light from ultra-violet to the visible range. The photocatalysts are synthesized using an easy aqueous route allowing “green conditions” for synthesis. For comparative purposes, the corresponding pure TiO2 and a grafted catalyst are also synthesized and studied. For all samples, a mixture of anatase/brookite TiO2 is obtained, resulting in crystalline materials with low temperature synthesis. The three porphyrin-doped samples prepared in water prove to be efficient photocatalysts for the degradation of p-nitrophenol (PNP) under visible light, and an improvement in photoactivity is observed when the amount of porphyrin increases. The photocatalyst activity is very stable over time as the PNP degradation remains nearly constant after 264 h of testing, showing no leaching of porphyrin. In recycling tests, the grafted sample presents bond breaking between POR-Si and TiO2 and a decrease in photoactivity towards pure TiO2 sample activity. A comparison with the commercial Evonik P25 catalyst shows that the porphyrin-doped TiO2 is nearly 6 times more photoactive under visible light for PNP degradation. [less ▲]

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See detailSol-gel syntheses of photocatalysts for the removal of pharmaceutical products in water
Belet, Artium ULiege; Wolfs, Cédric ULiege; Mahy, Julien ULiege et al

in Nanomaterials (2019), 9

A screening study on seven photocatalysts was performed to identify the best candidate for pharmaceutical products degradation in water. Photocatalysts were deposited as thin films through a sol-gel ... [more ▼]

A screening study on seven photocatalysts was performed to identify the best candidate for pharmaceutical products degradation in water. Photocatalysts were deposited as thin films through a sol-gel process and subsequent dip-coating on glass slides. The efficiency of each photocatalyst was assessed through the degradation of methylene blue first, and then, through the degradation of fifteen different pharmaceutical products. Two main types of synthesis methods were considered: aqueous syntheses, where the reaction takes place in water, and organic syntheses, where reactions take place in an organic solvent and only a stoichiometric amount of water is added to the reaction medium. Photocatalysts synthesized via aqueous sol-gel routes showed relatively lower degradation efficiencies; however, the organic route required a calcination step at high temperature to form the photoactive crystalline phase, while the aqueous route did not. The best performances for the degradation of pharmaceuticals arose when Evonik P25 and silver nanoparticles were added to TiO2, which was synthesized using an organic solvent. In the case of methylene blue degradation, TiO2 modified with Evonik P25 and TiO2 doped with MnO2 nanoparticles were the two best candidates. [less ▲]

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See detailDurable photocatalytic thin coatings for road applications
Mahy, Julien ULiege; Pàez Martinez, Carlos ULiege; Hollevoet, Jonas et al

in Construction and Building Materials (2019), 215

In this study, 6 different coatings have been developed as photocatalytic coatings based on TiO2, which can be applied to concrete for road applications. The goal of these coatings is to degrade ... [more ▼]

In this study, 6 different coatings have been developed as photocatalytic coatings based on TiO2, which can be applied to concrete for road applications. The goal of these coatings is to degrade pollutants such as nitrogen oxides and volatile organic compounds emitted by road transport. The coatings are synthesized by sol-gel process in organic or water solvent or by a functionalization technique with hydroxybenzoic acid on commercial TiO2 nanoparticles (P25). These suspensions are deposited by dip-coating or spray-coating on three different concrete substrates: pavement blocks, brushed or exposed aggregates road concrete. For each process, particular attention has been paid to the development of TiO2 synthesis that will be easily produced on a larger scale. The samples are characterized with photocatalytic test on NOx degradation, mechanical resistance test and resistance to freeze-thaw cycles in presence of de-icing salts. Except from the samples resulting from the sol-gel organic route, all other samples show a NOx degradation between 10 and 45%. From resistance point of view, the best coating is the TiO2 P25/E coating synthesized by functionalization of P25 nanoparticles. Results highlight that anatase TiO2 is well present at the surface of the sample and an optimal TiO2 loading exists for this coating. The TiO2 P25/E coating shows promising properties for road applications. [less ▲]

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See detailSynthesis of Ni/γ-Al2O3-SiO2 catalysts with different silicon precursors for the steam toluene reforming
Claude, Vincent; Mahy, Julien ULiege; Geens, Jérémy ULiege et al

in Microporous and Mesoporous Materials (2019), 284

This work investigated the intrinsic properties and performances of Ni/γ-Al2O3-SiO2 modified with different silicon precursors for the steam reforming of toluene in biomass gasifier exit conditions (8000 ... [more ▼]

This work investigated the intrinsic properties and performances of Ni/γ-Al2O3-SiO2 modified with different silicon precursors for the steam reforming of toluene in biomass gasifier exit conditions (8000 ppmv of toluene, 650 °C). Samples were synthesized by an aqueous sol-gel process in presence of aluminum nitrate, nickel nitrate and the use of either tetramethoxysilane (TMOS, Si-(OCH3)4) or tetraethoxysilane (TEOS, Si-(OC2H5)4) in order to understand the influence of the reactivity of the silicon precursor. Furthermore, the use of N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDAS, (OCH3)3-Si-(CH2)3-NH-(CH2)2-NH2) is also investigated in order to understand the influence of a silicon precursor containing an ethylenediamine group, able to complex Ni2+ ions. By the chelation of Ni2+ ions by ethylenediamine groups during the synthesis, Ni/γ-Al2O3-SiO2 samples modified with EDAS showed higher dispersion of the metallic Ni nanoparticles and the higher resistance against the sintering of Ni particles. This was also attributed to the high microporous volume and the narrow mesoporous distribution of the support, which could also prevent the migration of the metallic Ni nanoparticles. The catalytic tests revealed that the reactivity of the silicon precursor played a major role on the conversion of toluene. For alumina supports modified with a silicon precursor with a low reactivity such as TEOS, the low integration of the Si atoms inside the bulk alumina lead to a slightly higher catalytic activity, but also to a high formation of structured carbon. The opposite effect was observed for the samples modified with a highly reactive silicon precursor, such as TMOS or EDAS, which showed a slightly lower catalytic activity, but a higher resistance against coking compared to pure Ni/γ-Al2O3 catalysts. [less ▲]

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See detailTailored films and biomaterials: another reality
Mahy, Julien ULiege; Wolfs, Cédric ULiege; Tilkin, Rémi ULiege et al

Poster (2018, December 10)

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See detailModification inorganique d’une argile locale: Application au traitement des eaux
Benhebal, Hadj; Kadi, Samir; Lellou, Salima et al

Poster (2018, December)

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See detailElaboration de matériaux zéolithiques à partir d'argiles locales: Application au traitement des eaux
Benhebal, Hadj; Kadi, Samir; Lellou, Salima et al

Poster (2018, December)

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See detailEasy-cleaning and photocatalytic materials
Mahy, Julien ULiege; léonard, Géraldine; Zubiaur, Anthony ULiege et al

Conference (2018, November 20)

Dans ce travail, un procédé sol-gel en phase aqueuse a été développé pour produire à grande échelle un photocatalyseur à base de TiO2 présentant des propriétés hydrophiles et une activité photocatalytique ... [more ▼]

Dans ce travail, un procédé sol-gel en phase aqueuse a été développé pour produire à grande échelle un photocatalyseur à base de TiO2 présentant des propriétés hydrophiles et une activité photocatalytique élevée pour la dépollution de l'eau et de l'air. La première étape consistait à développer une synthèse sol-gel en phase aqueuse de TiO2 pur à l'échelle du laboratoire. Le protocole de synthèse a été simplifié pour réduire le temps de synthèse, la température et le nombre d’étapes comme les étapes de lavage. Les propriétés physico-chimiques et photocatalytiques du matériau obtenu ont été caractérisées pour évaluer la production d'un revêtement hydrophile sur acier inoxydable et la formation d'un photocatalyseur efficace sur la dégradation de trois polluants (bleu de méthylène, p-nitrophénol ou acétaldéhyde) sous différentes formes (film ou poudre) et dans différentes phases (liquide ou gazeuse). Dans la deuxième partie, la synthèse aqueuse a été adaptée pour produire des catalyseurs de TiO2 dopés avec des ions Fe3+, Ag+, Cu2+, Zn2+, Cr3+, Al3+, Mn2+ et Co2+ et des nanoparticules métalliques de Pt afin d'améliorer leur activité. Certains dopants ont montré une photoactivité accrue et certains mécanismes ont été proposés pour expliquer ces modifications de l'activité avec le dopage. En outre, la comparaison des coûts à l'échelle du laboratoire a montré que le dopage au Zn2+ pouvait être envisagé pour des applications industrielles. En utilisant cette méthode, un photocatalyseur de TiO2 dopé au Zn a été synthétisé à grande échelle et a montré des propriétés homologues au produit à l'échelle du laboratoire. La troisième étape consistait à étudier la propriété de redispersion des colloïdes de TiO2 nanocristallins. En effet, les poudres obtenues par séchage sous air de ces colloïdes peuvent être redispersées dans l'eau pour produire des colloïdes qui sont comparés à ceux obtenus initialement. Cinq cycles de séchage-redispersion ont été réalisés sur des colloïdes sélectionnés. Un mécanisme a été proposé pour expliquer cette propriété intéressante, l'acide présent dans la synthèse semble être le facteur principal. Cela peut être très utile pour une application industrielle de cette synthèse permettant de réduire le volume et le poids pour le transport et le stockage. [less ▲]

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See detailAqueous N-Doped TiO2 Catalysts for Visible Light Photocatalytic Applications
Mahy, Julien ULiege; Cerfontaine, Vincent; Poelman, Dirk et al

Poster (2018, November)

In this work, TiO2 prepared with an aqueous sol-gel synthesis by peptization process is doped with nitrogen precursor to extend its activity towards the visible region. Three N-precursors are used: urea ... [more ▼]

In this work, TiO2 prepared with an aqueous sol-gel synthesis by peptization process is doped with nitrogen precursor to extend its activity towards the visible region. Three N-precursors are used: urea, ethylenediamine and triethylamine. Different molar N/Ti ratios are tested and the synthesis is adapted for each dopant. For urea- and trimethylamine-doped samples, anatase-brookite TiO2 nanoparticles of 6–8 nm are formed, with a specific surface area between 200 and 275 m2 g−1. In ethylenediamine-doped samples, the formation of rutile phase is observed, and TiO2 nanoparticles of 6–8 nm with a specific surface area between 185 and 240 m2 g−1 are obtained. X-ray photoelectron spectroscopy (XPS) and diffuse reflectance measurements show the incorporation of nitrogen in TiO2 materials through Ti–O–N bonds allowing light absorption in the visible region. Photocatalytic tests on the remediation of water polluted with p-nitrophenol show a marked improvement for all doped catalysts under visible light. The optimum doping, taking into account cost, activity and ease of synthesis, is up-scaled to a volume of 5 L and compared to commercial Degussa P25 material. This up-scaled sample shows similar properties compared to the lab-scale sample, i.e., a photoactivity 4 times higher than commercial P25. [less ▲]

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See detailSpray-coating as a scalable means for making TiO2 thin films in the context of advanced oxidative processes
Wolfs, Cédric ULiege; Mahy, Julien ULiege; Mertes, Alexander ULiege et al

Conference (2018, October 29)

Micropollutants are introduced into the environment by domestic, industrial or hospital waste waters. TiO2 photocatalysis is an efficient and versatile way of removal of these micropollutants. However ... [more ▼]

Micropollutants are introduced into the environment by domestic, industrial or hospital waste waters. TiO2 photocatalysis is an efficient and versatile way of removal of these micropollutants. However, efficient, low-cost production of TiO2 thin films is not straightforward in the case of big reactors. Spray-coating is presented as the better solution cost-wise, and as a similar solution efficiency-wise. [less ▲]

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See detailEfficient P/N and Ag-doped titania for the photocatalytic degradation of waste water organic pollutants
Mahy, Julien ULiege; Bodson, Céline; Cerfontaine, Vincent et al

Conference (2018, October 04)

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See detailHeterogeneous photocatalysis for water and air depollution
Mahy, Julien ULiege

Doctoral thesis (2018)

In this work, a TiO2 aqueous sol-gel process was developed to produce, at large scale, photocatalysts with hydrophilic property and high activity, both under visible and UV/visible light, for water and ... [more ▼]

In this work, a TiO2 aqueous sol-gel process was developed to produce, at large scale, photocatalysts with hydrophilic property and high activity, both under visible and UV/visible light, for water and air remediation. The first step was to develop an easy aqueous sol-gel synthesis of pure TiO2 at laboratory scale. The synthesis protocol was simplified to reduce the synthesis time, the temperature and the number of steps as washing step. The physico-chemical and photocatalytic properties of the obtained materials have been characterized to assess the production of hydrophilic coatings on stainless steel and the formation of efficient photocatalysts for the degradation of three pollutants (methylene blue, p-nitrophenol or acetaldehyde) under different shapes (film or powder) and in different phases (liquid or gaseous). Then this synthesis has been up-scaled to a volume of 5 L and deposited with a pilot line on stainless steel. The produced coating was characterized and compared to the laboratory material to show the successful operation of up-scaling. In second part, the aqueous synthesis was adapted to produce TiO2 catalysts doped with Fe3+, Ag+, Cu2+, Zn2+, Cr3+, Al3+, Mn2+, and Co2+ ions and Pt metallic nanoparticles in order to improve their activity. Some dopants showed an increased photoactivity and some mechanisms were proposed to explain these modifications of activity with doping. Furthermore, cost comparison at laboratory scale showed that Zn2+ doping may be considered for industrial applications. Using this method, a large scale Zn-doped TiO2 photocatalyst was synthesized with properties homologous to the lab-scale product. The third step was to study the redispersion property of the nanocrystalline TiO2 colloids. Indeed, the powders obtained by air drying of these colloids can be redispersed in water to produce colloids which are compared to the initial one. Five cycles of drying-redispersion were achieved on selected colloids. A mechanism was proposed to explain this interesting property, acid present in the synthesis seems to be the main factor. This would be very useful for an industrial application of this synthesis allowing to reduce the volume and weight for transportation and storage. In the last part of this work, the aqueous TiO2 photocatalyst was modified to extend his activity towards visible light. In this aim, silylated porphyrin and nitrogen-based reagents were used. The silylated porphyrin was synthesized in laboratory and co-hydrolysed with a titanium precursor in aqueous medium to produce hybrid TiO2 photocatalyst. Results showed that the porphyrin fragments are held to the resulting matrix through strong Si-O-Ti covalent bonds limiting leaching of the former and an increased photoactivity under visible was obtained. Concerning nitrogen doping, three N-precursors were used: urea, ethylenediamine and triethylamine. Results showed the incorporation of nitrogen in TiO2 materials allowing absorption in visible region and improvement in visible activity on the remediation of polluted water with p-nitrophenol. The best doping, regarding cost, activity and ease of synthesis, was successfully up-scaled to volume of 5 L and compared to commercial Degussa P25 material. [less ▲]

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See detailLarge scale production of photocatalytic TiO2 coating for volatile organic compound (VOC) air remediation
Mahy, Julien ULiege; Lambert, Stéphanie ULiege; Geens, Jérémy ULiege et al

in AIMS Materials Science (2018), 5(5), 945-956

In this work, a pure TiO2 colloid was produced at pilot scale of 5 L and deposited on stainless steel with a pilot roll-to-roll line to produce photocatalytic coating for VOC degradation. The pure TiO2 ... [more ▼]

In this work, a pure TiO2 colloid was produced at pilot scale of 5 L and deposited on stainless steel with a pilot roll-to-roll line to produce photocatalytic coating for VOC degradation. The pure TiO2 colloid was synthesized with an aqueous sol–gel process, producing crystalline nanoparticles around 4–5 nm (mainly anatase phase) dispersed in water. The crystalline phases were produced at low temperature (<100 ℃) without calcination step. The crystalline coating produced with roll-to-roll process was very thin, around 50 nm. The photoactivity of this coating towards VOC destruction was evaluated on the degradation of acetaldehyde; the measured activity of the coating was 35 ± 5%. With the use of mass spectrometer, it was shown that acetaldehyde was mainly converted in CO2. The durability of the coating was assessed after 1, 2 and 3 weeks, and showed that the photoactivity stayed constant for this period. [less ▲]

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See detailAcid acting as redispersing agent to form stable colloids from photoactive crystalline aqueous sol–gel TiO2 powder
Mahy, Julien ULiege; Deschamps, Fabien ULiege; Collard, Valérie ULiege et al

in Journal of Sol-Gel Science and Technology (2018), 87

In this work, the redispersion of three nanocrystalline TiO2 colloids is studied: one pure and two Fe-doped titania. These three colloids are produced by an easy aqueous sol-gel synthesis using ... [more ▼]

In this work, the redispersion of three nanocrystalline TiO2 colloids is studied: one pure and two Fe-doped titania. These three colloids are produced by an easy aqueous sol-gel synthesis using precipitation-acidic peptization of Ti precursor. For the two Fe-doped TiO2, one is doped during synthesis (primary doping) and the other is doped after the synthesis (secondary doping). The initial colloids are composed of crystalline TiO2 particles around 7 nm with good photocatalytic properties, tested on PNP degradation under visible light (wavelength > 390 nm). The powders obtained by air drying of these three colloids are redispersed in water to produce colloids which are compared to the initial colloid produced. For each colloid, 5 cycles of drying-redispersion are achieved. The colloids are characterized by dynamic light scattering, zeta potential measurements, inductively coupled plasma–atomic emission spectroscopy, X-ray diffraction, nitrogen adsorption-desorption measurements, Mössbauer spectroscopy, diffuse reflectance spectroscopy, and photocatalytic tests. The results show that similar products are obtained between the cycles, maintaining homologous properties of colloids. This property of redispersion is mainly due to the acid (HNO3, HCl, or H2SO4) which protonates the surface of the TiO2 nanoparticle leading to high surface charges and electrostatic repulsions between aggregates. This property can be very useful for industrial applications of this synthesis, especially as it allows the volume and weight to be reduced for transportation and storage. Moreover, results show that the pure TiO2 powder can be doped during its redispersion step. The redispersion of the TiO2 developed here is possible without surface functionalization or multiple step processes, contrary to commercial Degussa P25. A two year stability study of all the produced colloids has been performed by following the evolution of the macroscopic aspect and the physico-chemical properties of these sols. This study showed high stability of the produced colloids. [less ▲]

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See detailHighly Efficient Low-Temperature N-Doped TiO2 Catalysts for Visible Light Photocatalytic Applications
Mahy, Julien ULiege; Cerfontaine, Vincent; Poelman, Dirk et al

in Materials (2018), 11(584),

In this paper, TiO2 prepared with an aqueous sol-gel synthesis by peptization process is doped with nitrogen precursor to extend its activity towards the visible region. Three N-precursors are used: urea ... [more ▼]

In this paper, TiO2 prepared with an aqueous sol-gel synthesis by peptization process is doped with nitrogen precursor to extend its activity towards the visible region. Three N-precursors are used: urea, ethylenediamine and triethylamine. Different molar N/Ti ratios are tested and the synthesis is adapted for each dopant. For urea- and trimethylamine-doped samples, anatase-brookite TiO2 nanoparticles of 6–8 nm are formed, with a specific surface area between 200 and 275 m2·g−1. In ethylenediamine-doped samples, the formation of rutile phase is observed, and TiO2 nanoparticles of 6–8 nm with a specific surface area between 185 and 240 m2·g−1 are obtained. X-ray photoelectron spectroscopy (XPS) and diffuse reflectance measurements show the incorporation of nitrogen in TiO2 materials through Ti–O–N bonds allowing light absorption in the visible region. Photocatalytic tests on the remediation of water polluted with p-nitrophenol show a marked improvement for all doped catalysts under visible light. The optimum doping, taking into account cost, activity and ease of synthesis, is up-scaled to a volume of 5 L and compared to commercial Degussa P25 material. This up-scaled sample shows similar properties compared to the lab-scale sample, i.e., a photoactivity 4 times higher than commercial P25. [less ▲]

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See detailInteractions between Zn2+ or ZnO with TiO2 to produce an efficient photocatalytic, superhydrophilic and aesthetic glass
Léonard, Géraldine ULiege; Pàez Martinez, Carlos ULiege; Ramirez, Alfonso et al

in Journal of Photochemistry and Photobiology A: Chemistry (2018), 350

Zinc was coupled with titanium dioxide using different methods. SiO2 and Zn-SiO2 doped TiO2 films, on the one hand, and Zn doped TiO2 on the other hand, have been produced using controlled sol-gel ... [more ▼]

Zinc was coupled with titanium dioxide using different methods. SiO2 and Zn-SiO2 doped TiO2 films, on the one hand, and Zn doped TiO2 on the other hand, have been produced using controlled sol-gel processes by alcoholic, cogelation and aqueous ways. From these syntheses, films were deposited on soda lime glass. These samples were compared to ZnO samples but also to bilayer samples constituting one layer of TiO2 and one layer of ZnO. The physico-chemical properties of the films were characterized by grazing-incidence X-ray diffraction, profilometry and UV-Vis absorption analyses. The photocatalytic activity has been evaluated from the degradation of methylene blue under UV-A light, from the degradation of p-nitrophenol under visible light and from the degradation of H2O2 under halogen light (UV-A + visible light). Superhydrophilicity was evaluated from contact angle measurement after UV exposition and also from hysteresis effects. Finally, a haze measurement was performed to evaluate the impact of the coating on the aesthetic property of the coated glass. Aqueous films have better photocatalytic activity and superhydrophilicity than samples from alcoholic synthesis. The crystallization of the sample appears to be one key factor: alcoholic films required calcination to ensure the crystallization of TiO2, but the alkali migration from the glass support prevents this crystallisation, while aqueous synthesis promotes crystallized particles at low temperatures without alkali interference. It appears that the relative activity from one sample to another depends on the nature of the illumination and on the nature of the molecule to be degraded. Nevertheless, the sample with ZnO layer deposited on first TiO2 layer (ZnO 500 Alc/TiO2 100 AQ) composite is found to be the best sample, maintaining a high hydrophilicity similar to TiO2 and a good activity. [less ▲]

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