References of "Zubiaur, Anthony"
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See detailTunable carbon-supported catalyst materials processed by low-pressure plasma treatments of solid precursors
Pireaux, Jean-Jacques; da Silva Pires, Mathieu; Bocchese, Fabrice et al

Conference (2019, February)

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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 detailSynthesis, characterization, and durability study of PtCo hollow nanoparticles deposited on carbon xerogel as electrocatalysts for Proton Exchange Membrane Fuel Cells
Zubiaur, Anthony ULiege; Asset, Tristan; Deschamps, Fabien ULiege et al

Poster (2018, July)

Proton exchange membrane fuel cell (PEMFC) catalysts are generally made of carbon black (CB)-supported platinum-based nanoparticles, and the PEMFC electrodes display high Pt loading (up to 0.5 mgPt/cm² ... [more ▼]

Proton exchange membrane fuel cell (PEMFC) catalysts are generally made of carbon black (CB)-supported platinum-based nanoparticles, and the PEMFC electrodes display high Pt loading (up to 0.5 mgPt/cm²) to reach high current without severe mass transport issues. To decrease the system cost, the decrease of the Pt mass contained in the PEMFC electrodes, in particular at the cathode where the oxygen reduction reaction (ORR) proceeds, remains a major challenge. Improving the mass activity of the catalyst towards ORR is currently best achieved by alloying Pt with 3d-transition metal atoms such as cobalt or nickel. These alloys perform better for the ORR because the substitution of some Pt atoms by 3d-metal atoms with smaller radius leads to a modified Pt electronic structure [1]. Therefore, the Pt loading of the electrode can be decreased by increasing the catalyst mass activity through alloying. Moreover, the properties of CBs, as described by Rodríguez-Reinoso [2], are not optimal for electrocatalysis; in particular, the electrode pore texture after processing (which includes hot-pressing) cannot be controlled. A possible solution to the drawbacks of CBs is the use of synthetic nanostructured materials with a controllable and reproducible pore texture and with a pure, known and constant chemical composition; carbon xerogels (CX) exhibit such properties [3]. Recently, various highly dispersed CX-supported Pt catalysts (Pt/CX), made of 3-4 nm metal nanoparticles, have been synthesized via several methods, such as the strong electrostatic adsorption (SEA), the charge enhanced dry impregnation (CEDI), or the liquid phase reduction of Pt ions with formic acid [4]. Their performances were found quite comparable to those of up-to-date commercial Pt/carbon black electrocatalysts. Another major challenge for the extensive worldwide commercialization of PEMFCs is the stability of the catalysts. Indeed, the stability of the Pt-based nanoparticles, as shown in Fig. 1a and 1b, has to be improved in order to increase the lifetime of PEMFCs [5]. A way to improve the durability of the catalyst is to use new and stable particle structures, such as hollow nanoparticles. The synthesis and performance of hollow PtCo nanoparticles/CX (Fig. 1c) are currently studied by our group. The synthesis consists in the formation of a Co nanoparticle colloid using citrate molecules as complexing agents, followed by the galvanic replacement of Co atoms by Pt ions and, then, by the diffusion of the remaining core Co atoms through/in the Pt shell. The results indicate that the ORR specific activity (expressed in A/mPt²) and the ORR mass activity (expressed in A/gPt) of the bimetallic hollow particles dispersed on CX are ca. 15 or 7 times higher than that of commercial pure Pt/CB, respectively. The durability of the hollow PtCo/CX catalyst was studied in a three-electrode cell and in a PEMFC electrode. In particular, accelerated stress tests (ASTs, i.e. 30,000 potential cycles between 0.6 and 1.0 V), performed in PEMFC assemblies, show that the hollow structure is stable: hollow particles present in the pristine catalyst (Fig. 1c) are still observed after cycling (Fig. 1d). Moreover, the performance of the cell constituted of the hollow PtCo/CX catalyst stabilizes: while Pt/C catalyst show a continuous performance drop, no further performance decrease is observed after the 10,000 first AST cycles, proving the good stability of this catalyst (Fig. 2). [less ▲]

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See detailStreamlining of the synthesis process of Pt/carbon xerogel electrocatalysts with high Pt loading for the oxygen reduction reaction in proton exchange membrane fuel cells applications
Zubiaur, Anthony ULiege; Job, Nathalie ULiege

in Applied Catalysis B: Environmental (2018)

Pt/carbon xerogel catalysts were synthesized by different methods. The strong electrostatic adsorption (SEA) method, which consists in enhancing electrostatic interactions between the support and the ... [more ▼]

Pt/carbon xerogel catalysts were synthesized by different methods. The strong electrostatic adsorption (SEA) method, which consists in enhancing electrostatic interactions between the support and the precursor, was first modified in order to avoid any Pt loss (charge enhanced dry impregnation, CEDI). In a second step, the synthesis was rationalized to speed up the reduction (liquid phase reduction with sodium borohydride, NaBH4). The synthesis procedure was further simplified in order to obtain one-step procedures, such as (i) reduction of highly loaded platinum solution by sodium borohydride, (ii) formic acid reduction, and (iii) colloid synthesis. All the catalysts were analyzed by physicochemical and electrochemical methods. They are compared to a reference commercial catalyst (Tanaka). The best performances are obtained by the SEA, the CEDI and the formic acid reduced catalysts, the performance of which are at least equal to, or even higher (up to 20–25% in mass activity) than those of the commercial reference. From these three methods, the only one-step method is the formic acid reduction, which allows avoiding time-consuming drying and H2 reduction steps. [less ▲]

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See detailDevelopment of new catalysts for proton exchange membrane fuel cells (PEMFCs)
Zubiaur, Anthony ULiege

Doctoral thesis (2017)

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See detailSynthesis, characterization, and durability study of Pt-Co hollow nanoparticles deposited on carbon xerogel electrocatalysts for Proton Exchange Membrane Fuel Cells (PEMFC)
Zubiaur, Anthony ULiege; Asset, Tristan ULiege; Olu, Pierre-Yves et al

Poster (2017, September)

Proton exchange membrane fuel cell (PEMFC) catalysts are generally made of carbon black (CB)supported platinum-based nanoparticles. However, the properties of CBs, as described by RodríguezReinoso [1 ... [more ▼]

Proton exchange membrane fuel cell (PEMFC) catalysts are generally made of carbon black (CB)supported platinum-based nanoparticles. However, the properties of CBs, as described by RodríguezReinoso [1], are not optimal for electrocatalysis. A possible solution to the drawbacks of CBs is the use of synthetic nanostructured materials with a controllable and reproducible texture and with a pure, known and constant chemical composition; carbon xerogels (CX) exhibit such properties [2]. Recently, various highly dispersed CX-supported Pt nanoparticles catalysts (Pt/CX) have been synthesized via several methods, such as the strong electrostatic adsorption (SEA) [3] or the charge-enhanced dry impregnation (CEDI) [4]. However, the decrease of the Pt mass contained in the PEMFC electrodes, in particular at the cathode where the oxygen reduction reaction (ORR) is processed, remains a major challenge. Improving the ORR mass activity is currently best achieved by alloying Pt with 3d-transition metal atoms such as cobalt (Co). These alloys perform better than the ORR because the substitution of some Pt atoms by 3d-metal atoms with smaller radius leads to a modified Pt electronic structure [5]. The synthesis and durability of Pt-Co hollow particles/CX (Fig. 1) is currently being studied in our groups. The results indicate that the specific and mass activity of the bimetallic hollow particles dispersed on CX is ca. 10 times higher than that of pure Pt/CB. The first durability results show good stability of the hollow particles structure. Performances and accelerated stress tests (ASTs) in PEMFCs were finally performed. [less ▲]

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See detailHighly efficient doped nanocristalline TiO2 for water Treatment
Mahy, Julien ULiege; Léonard, Géraldine ULiege; Zubiaur, Anthony ULiege et al

Conference (2017, July 13)

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See detailCarbon gel-supported catalysts for PEM fuel cell catalytic layers
Zubiaur, Anthony ULiege; Asset, Tristan; Deschamps, Fabien ULiege et al

Conference (2017, March 03)

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See detailTowards a large scale aqueous sol-gel synthesis of doped TiO2: Study of various metallic dopings for the photocatalytic degradation of p-nitrophenol
Mahy, Julien ULiege; Lambert, Stéphanie ULiege; Léonard, Géraldine ULiege et al

in Journal of Photochemistry and Photobiology A: Chemistry (2016), 329

In this paper, an easy aqueous sol-gel synthesis developed previously by Mahy et al. [J. Sol-Gel Sci. Technol. (2016)] is adapted to produce highly active TiO2 catalysts doped with Fe3+, Ag+, Cu2+, Zn2 ... [more ▼]

In this paper, an easy aqueous sol-gel synthesis developed previously by Mahy et al. [J. Sol-Gel Sci. Technol. (2016)] is adapted to produce highly active TiO2 catalysts doped with Fe3+, Ag+, Cu2+, Zn2+, Cr3+, Al3+, Mn2+, and Co2+ ions and Pt metallic nanoparticles. Samples are characterized by inductively coupled plasma–atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), Mössbauer spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption–desorption measurements and diffuse reflectance spectroscopy measurements. Results show that the samples are composed of anatase-brookite TiO2 nanoparticles with a spherical shape and mean diameter of around 5-8 nm and a surface area of between about 150 - 250 m2 g-1. In each doped sample, the dopant is present in the form added during the synthesis, given that the sample has not undergone any particular treatment. Photoactivity tests show improvement in catalyst activity for Fe3+, Ag+, Cu2+, Zn2+, and Al3+ ion and Pt metallic nanoparticle dopants, while a decrease of activity is obtained for Cr3+, Mn2+ and Co2+ ion dopants. For some dopants, the activity of TiO2 doped with metallic ions and synthesized from the aqueous sol-gel process is equal or superior to the activity of the commercial photocatalyst Degussa P25. Some mechanisms are proposed to explain these modifications of activity with doping. Furthermore, cost comparison at laboratory scale showed that Zn and Cu nitrate salt dopings are clearly less expensive for a halogen light (UV/visible) or low energy light enhanced catalyst and may be considered for industrial applications. Using this method, a large scale Zn-doped TiO2 photocatalyst is synthesized with properties homologous to the lab-scale product. Results show that the aqueous sol-gel synthesis developed previously can be easily adapted for doping in order to produce an up-scalable synthesis. [less ▲]

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See detailDevelopment of a large scale aqueous sol-gel synthesis of doped TiO2
Mahy, Julien ULiege; Lambert, Stéphanie ULiege; Léonard, Géraldine ULiege et al

Conference (2016, July 20)

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See detailPt-Ni Hollow Nanoparticles for Oxygen Reduction Reaction: Controlling the Nanoparticles Morpholo-gy
Asset, Tristan ULiege; Chattot, Raphaël; Zubiaur, Anthony ULiege et al

Poster (2015, October 15)

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See detailPt-Ni Hollow Nanoparticles for Oxygen Reduction Reaction : Controlling the Nanoparticle Morphology
Asset, Tristan ULiege; Zubiaur, Anthony ULiege; Chattot, Raphael et al

Poster (2015, September 13)

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See detailDesign of Pt/carbon xerogel catalysts for PEM fuel cells
Job, Nathalie ULiege; Lambert, Stéphanie ULiege; Zubiaur, Anthony ULiege et al

in Catalysts (2015), 5

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See detailHighly dispersed iron xerogel catalysts for p-nitrophenol degradation by photo-Fenton effects
Mahy, Julien ULiege; Tasseroul, Ludivine ULiege; Zubiaur, Anthony ULiege et al

in Microporous and Mesoporous Materials (2014), 197

Several iron xerogel catalysts were synthesized by hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) which is able to form a chelate with iron ... [more ▼]

Several iron xerogel catalysts were synthesized by hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) which is able to form a chelate with iron ions. The EDAS/TEOS ratio strongly influences the texture of xerogel catalysts. The specific surface area and the micro- and mesoporous volume increase with this ratio. It seems that EDAS plays a nucleating agent role for silica particles and allows to anchor Fe-based moieties inside the silica network. Iron oxide nanoparticles of diameter 1-1.5 nm and Fe3+ ions result, encapsulated in silica particles with sizes of about 10-30 nm in diameter. The iron species was determined by Mössbauer spectroscopy and magnetometry measurements and only Fe3+ species were observed in xerogel catalysts. The Fenton and photo-Fenton effect of these catalysts were evaluated on the degradation of p-nitrophenol in aqueous media under different conditions. Results show that in the presence of H2O2, iron xerogel catalysts present a photo-Fenton effect, reaching 99 % of degradation after 24 h. [less ▲]

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See detailSynthesis of Pt/Carbon Xerogel Electrocatalysts for PEM Fuel Cells by the Multiple SEA Method
Zubiaur, Anthony ULiege; Chatenet, Marian; Maillard, Frédéric et al

Poster (2014, July)

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See detailHighly dispersed iron xerogel catalysts for p-nitrophenol degradation by photo-Fenton effects
Mahy, Julien ULiege; Tasseroul, Ludivine ULiege; Zubiaur, Anthony ULiege et al

Poster (2014, July)

Since the beginning of the industrial era, the various human activities have increased steadily, leading to a rapid technological development and a high population growth. Thus, the expansion of the ... [more ▼]

Since the beginning of the industrial era, the various human activities have increased steadily, leading to a rapid technological development and a high population growth. Thus, the expansion of the industry has heavily polluted the atmosphere, soil and water with negative consequences for humans and environment [1]. To decrease this pollution, it exists various treatment methods: chemical, physical and biological [2,3]. Among all these methods, a recent way of treatment is the degradation of pollutants in soils or waters by Fenton and photo-Fenton reactions [3] which use H2O2, iron-based compounds and UV light. In this way, several Fe2O3/SiO2 xerogel catalysts were synthesized by cogelation method by hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) which is able to form a chelate with iron ions [4]. Five samples were synthesized: four samples with different percentage of iron (0.5, 1, 1.5 and 2.5 theoretical wt% confirmed by ICP-AES measurements), and a sample of pure silica. TEM pictures, nitrogen adsorption-desorption and mercury porosimetry measurements have established that EDAS plays a role of nucleating agent of silica particles [5,6] and allows to anchor iron particles inside silica network [4]. Indeed, it results iron nanoparticles of diameter 1-1.5 nm encapsulated in silica particles with sizes of about 10-30 nm in diameter. The species of iron was determined by Mössbauer spectroscopy and only Fe3+ ions were observed in xerogel catalysts. Then, the Fenton and photo-Fenton effect of these catalysts were evaluated on the degradation of p-nitrophenol (PNP) in aqueous medium in different conditions. Results show that Fe2O3/SiO2 xerogels present a photo-Fenton effect with H2O2, reaching with a sample 99 % of degradation after 24 h. [1] M. A. Khan, A. M. Ghouri, Environmental pollution: its effects on life and its remedies, Journal of Arts, Science & Commerce (Vol. 2), 2011, pg 276-285. [2] M. S. Kuyukina , I. B. Ivshina, Biology of rhodococcus: chapter 9, Springer, 2010, pg 232-256. [3] J. J. Pignatello, E. Oliveros, A. MacKay, Advanced Oxidation Processes for Organic Contaminant Destruction Based on the Fenton Reaction and Related Chemistry, Critical Reviews in Environmental Science and Technology (Vol. 36), 2006, pg 1-84. [4] B. Heinrichs, L. Rebbouh, J.W. Geus, S. Lambert, H.C.L. Abbenhuis, F. Grandjean, G.J. Long, J.-P. Pirard, R.A. van Santen, Iron (III) species dispersed in porous silica through sol-gel chemistry, Journal of Non-Crystalline Solids (Vol. 354), 2008, pg 665-672. [5] S. Lambert, C. Alié, J.-P. Pirard, B. Heinrichs, Study of textural properties and nucleation phenomenon in Pd/SiO2 , Ag/SiO2 and Cu/SiO2 cogelled xerogel catalysts, Journal of Non-Crystalline Solids (Vol. 342), 2004, pg 70-81. [6] B. Heinrichs, S. Lambert , N. Job , J.-P. Pirard, in "Catalyst Preparation: Science and Engineering, J. R. Regalbuto (Ed.)", CRC Press, Taylor & Francis Group, Boca Raton, 2007, p. 163-208. [less ▲]

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