Publications by authors named "Philippe Knauth"

20 Publications

  • Page 1 of 1

Silica Containing Composite Anion Exchange Membranes by Sol-Gel Synthesis: A Short Review.

Polymers (Basel) 2021 Jun 4;13(11). Epub 2021 Jun 4.

Department of Industrial Engineering and International Laboratory "Ionomer Materials for Energy", University of Rome Tor Vergata, I-00133 Rome, Italy.

This short review summarizes the literature on composite anion exchange membranes (AEM) containing an organo-silica network formed by sol-gel chemistry. The article covers AEM for diffusion dialysis (DD), for electrochemical energy technologies including fuel cells and redox flow batteries, and for electrodialysis. By applying a vast variety of organically modified silica compounds (ORMOSIL), many composite AEM reported in the last 15 years are based on poly (vinylalcohol) (PVA) or poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) used as polymer matrix. The most stringent requirements are high permselectivity and water flux for DD membranes, while high ionic conductivity is essential for electrochemical applications. Furthermore, the alkaline stability of AEM for fuel cell applications remains a challenging problem that is not yet solved. Possible future topics of investigation on composite AEM containing an organo-silica network are also discussed.
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http://dx.doi.org/10.3390/polym13111874DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8200225PMC
June 2021

Nanocomposite Anion Exchange Membranes with a Conductive Semi-Interpenetrating Silica Network.

Membranes (Basel) 2021 Apr 4;11(4). Epub 2021 Apr 4.

MADIREL (UMR 7246) and International Laboratory, Ionomer Materials for Energy, Campus St Jérôme, Aix Marseille University, CNRS, 13013 Marseille, France.

Nanocomposite anion exchange membranes were synthesized based on poly(sulfone trimethylammonium) chloride. A hybrid semi-interpenetrating silica network containing a large amount of quaternary ammonium groups was prepared by two sol-gel routes, in situ with a single precursor, -trimethoxysilylpropyl-,,-trimethylammonium chloride (TMSP), or ex situ mixing two precursors, TMSP and 3-(2-aminoethylamino)propyldimethoxy-methylsilane (AEAPS). The properties of these hybrid composites and their degradation after immersion in 1 M KOH at 60 °C were studied. The degradation is reduced in the composite materials with a lower decrease in the ion exchange capacity. FTIR spectra showed that a main degradation mechanism with a single precursor TMSP is the dissolution of the hybrid silica network in KOH, whereas it is stable with the mixture of TMSP/AEASP. This conclusion is in agreement with the thermogravimetric analysis. The mechanical properties show a better ductility with a single precursor and higher stiffness and strength, but less ductility, by the ex situ route. The activation energy was between 0.25 and 0.14 eV for Cl and OH ion conduction, respectively, consistent with the migration mechanism.
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http://dx.doi.org/10.3390/membranes11040260DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8066660PMC
April 2021

Stability of Proton Exchange Membranes in Phosphate Buffer for Enzymatic Fuel Cell Application: Hydration, Conductivity and Mechanical Properties.

Polymers (Basel) 2021 Feb 2;13(3). Epub 2021 Feb 2.

CNRS, MADIREL (UMR 7246) and International Laboratory: Ionomer Materials for Energy, Aix Marseille Univ, Campus St. Jérôme, 13013 Marseille, France.

Proton-conducting ionomers are widespread materials for application in electrochemical energy storage devices. However, their properties depend strongly on operating conditions. In bio-fuel cells with a separator membrane, the swelling behavior as well as the conductivity need to be optimized with regard to the use of buffer solutions for the stability of the enzyme catalyst. This work presents a study of the hydrolytic stability, conductivity and mechanical behavior of different proton exchange membranes based on sulfonated poly(ether ether ketone) (SPEEK) and sulfonated poly(phenyl sulfone) (SPPSU) ionomers in phosphate buffer solution. The results show that the membrane stability can be adapted by changing the casting solvent (DMSO, water or ethanol) and procedures, including a crosslinking heat treatment, or by blending the two ionomers. A comparison with Nafion shows the different behavior of this ionomer versus SPEEK membranes.
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http://dx.doi.org/10.3390/polym13030475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7867367PMC
February 2021

Study of Annealed Aquivion Ionomers with the INCA Method †.

Membranes (Basel) 2019 Oct 17;9(10). Epub 2019 Oct 17.

University of Rome Tor Vergata, Department of Industrial Engineering and International Associated Laboratory: Ionomer Materials for Energy, Via del Politecnico 1, 00133 Roma, Italy.

We investigated the possibility to increase the working temperature and endurance of proton exchange membranes for fuel cells and water electrolyzers by thermal annealing of short side chain perfluorosulfonic acid (SSC-PFSA) Aquivion membranes. The Ionomer n Analysis (INCA method), based on n/T plots where n is a counter elastic force index, was applied to SSC-PFSA in order to evaluate ionomer thermo-mechanical properties and to probe the increase of crystallinity during the annealing procedure. The enhanced thermal and mechanical stability of extruded Aquivion 870 (equivalent weight, EW = 870 g·mol) was related to an increase of long-range order. Complementary differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) measurements confirmed the increase of polymer stiffness by the annealing treatment with an enhancement of the storage modulus over the whole range of temperature. The main thermomechanical relaxation temperature is also enhanced. DSC measurements showed slight base line changes after annealing, attributable to the glass transition and melting of a small amount of crystalline phase. The difference between the glass transition and melting temperatures derived from INCA plots and the ionic-cluster transition temperature derived from DMA measurements is consistent with the different experimental conditions, especially the dry atmosphere in DMA. Finally, the annealing procedure was also successfully applied for the first time to an un-crystallized cast membrane (EW = 830 g·mol) resulting in a remarkable mechanical and thermal stabilization.
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http://dx.doi.org/10.3390/membranes9100134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835819PMC
October 2019

"Intrinsic" Anion Exchange Polymers through the Dissociation of Strong Basic Groups: PPO with Grafted Bicyclic Guanidines.

Membranes (Basel) 2019 Apr 29;9(5). Epub 2019 Apr 29.

Dep. Industrial Engineering, and International Associated Laboratory: Ionomer Materials for Energy, University of Rome Tor Vergata, 00133 Roma, Italy.

We synthesized anion exchange polymers by a reaction of chloromethylated poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) with strongly basic 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). TBD contains secondary and tertiary amine groups in the guanidine portion. To favor the functionalization with the secondary amine, TBD was activated with butyl lithium. The yield of amine formation via the reaction of the benzyl chloride moiety with TBD was 85%. Furthermore, we prepared polymers with quaternary ammonium groups by the reaction of PPO-TBD with CHI. The synthesis pathways and ionomer structure were investigated by NMR spectroscopy. The thermal decomposition of both ionomers, studied by thermogravimetry, started above 200 °C, corresponding to the loss of the basic group. The ion exchange capacities, water uptake and volumetric swelling are also reported. The "intrinsic" anion conductivity of PPO-TBD due to the dissociation of grafted TBD was in the order of 1 mS/cm (Cl form). The quaternized ionomer (PPO-TBD-Me) showed an even larger ionic conductivity, above 10 mS/cm at 80 °C in fully humidified conditions.
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http://dx.doi.org/10.3390/membranes9050057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572084PMC
April 2019

Bottom-Up Electrochemical Deposition of Poly(styrene sulfonate) on Nanoarchitectured Electrodes.

ACS Appl Mater Interfaces 2017 Jul 28;9(27):22902-22910. Epub 2017 Jun 28.

Aix Marseille Univ (AMU) , CNRS, Madirel (UMR 7246), Electrochemistry of Materials Group, site St Jérôme, 13397 Marseille, France.

The cathodic deposition of poly(styrene sulfonate) on nanoarchitectured TiO electrodes is explored by cyclic voltammetry and potentiostatic and galvanostatic experiments, showing a diffusion-controlled deposition described by Cottrell's law. The structure and composition of the polymer is evidenced by various spectroscopic techniques, including nuclear magnetic resonance, Fourier transform infrared, and X-ray photoelectron spectroscopy, and its morphology is studied by scanning electron microscopy. The average chain length can be estimated from the NMR spectra. The electropolymerization mechanism initiates by radical anion formation. The cycling behavior in half-cell batteries against Li metal is excellent, especially at high rates explored up to 10 C. The areal insertion capacity is above recent literature results, up to 80 μA h cm. The combination of normalized areal power density and areal energy density is one of the best reported in the literature.
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http://dx.doi.org/10.1021/acsami.7b04335DOI Listing
July 2017

Porous NASICON-Type Li3Fe2(PO4)3 Thin Film Deposited by RF Sputtering as Cathode Material for Li-Ion Microbatteries.

Nanoscale Res Lett 2016 Dec 17;11(1):365. Epub 2016 Aug 17.

Aix-Marseille University, CNRS, MADIRELLaboratory, UMR 7246, 13397, Marseille, France.

We report the electrochemical performance of porous NASICON-type Li3Fe2(PO4)3 thin films to be used as a cathode for Li-ion microbatteries. Crystalline porous NASICON-type Li3Fe2(PO4)3 layers were obtained by radio frequency sputtering with an annealing treatment. The thin films were characterized by XRD, SEM, and electrochemical techniques. The chronoamperometry experiments showed that a discharge capacity of 88 mAhg(-1) (23 μAhcm(-2)) is attained for the first cycle at C/10 to reach 65 mAhg(-1) (17 μAhcm(-2)) after 10 cycles with a good stability over 40 cycles.
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http://dx.doi.org/10.1186/s11671-016-1574-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988962PMC
December 2016

Low-Permeability Poly(ether Ether Ketone)-Based Ampholytic Membranes.

Chempluschem 2016 Jun 17;81(6):550-556. Epub 2016 May 17.

University of Rome Tor Vergata (URoma2), Dip. Ingegneria Industriale, 00133, Roma, Italy.

Ion-exchange membranes based on sulfonated and sulfaminated poly(ether ether ketone) were prepared by a modified sulfamination route. In a first step, poly(ether ether ketone) was sulfonated. The sulfonic acid groups were then transformed into chlorosulfonic moieties by reaction with thionyl chloride. A proportion of the chlorosulfonic functionalities reacted with dimethylamine to give basic sulfonamide groups, whereas those remaining were hydrolyzed back to sulfonate moieties obtaining, after immersion in acidic solution, an ampholytic polymer. The thermal, mechanical, electrical, and permeability properties of these amphoteric membranes were characterized. These membranes exhibit good thermal and mechanical stability and ultra-low vanadium ion permeability. The type and value of ion conductivity can be adjusted by the choice of acidic or basic medium. The tunable ion conductivity and the low ion permeability are suitable characteristics for the development of high-performance separator membranes.
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http://dx.doi.org/10.1002/cplu.201600076DOI Listing
June 2016

Fluoride-ion-conducting Polymers: Ionic Conductivity and Fluoride Ion Diffusion Coefficient in Quaternized Polysulfones.

Chemphyschem 2015 Dec 2;16(17):3631-6. Epub 2015 Oct 2.

Aix Marseille University, CNRS, MADIREL (UMR 7246), Campus St Jerome, F-13397, Marseille, France.

We describe the three-step synthesis of a new polymeric fluoride ion conductor based on the fully aromatic polymer polysulfone (PSU). In the first step, PSU is chloromethylated (CM-PSU) using reagents (i.e., stannic chloride, paraformaldehyde, and trimethylchlorosilane) that are less toxic than those used in the standard procedure. In the second step, CM-PSU reacts with a tertiary amine (trimethylamine or 1,4-diazabicyclo[2.2.2]octane) to form quaternary ammonium groups fixed on the PSU backbone and mobile chloride counter-anions. The chloride ions can, in a third step, be exchanged with fluoride ions by immersion of the ionomer in NaF solution. The fluoride ion conductivity reaches 3-5 mS cm(-1) at 25 °C and 5-10 mS cm(-1) at 40 °C. We determined the F(-) diffusion coefficient in these ionomers by pulsed gradient spin-echo (PGSE) high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy and by impedance spectroscopy using the Nernst-Einstein relation. The diffusion coefficients determined by the two methods are in good agreement, ranging from 2 to 4×10(-10)  m(2)  s(-1) . The porosity and tortuosity of the ionomer membranes can be estimated.
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http://dx.doi.org/10.1002/cphc.201500643DOI Listing
December 2015

Simple approach for the fabrication of PEDOT-coated Si nanowires.

Beilstein J Nanotechnol 2015 4;6:640-50. Epub 2015 Mar 4.

Aix-Marseille University, Institut Matériaux Microélectronique Nanosciences de Provence-IM2NP, CNRS-UMR 7334, équipe OPTO-PV, Domaine Universitaire de Saint-Jérôme, Service 231, 13397 Marseille Cedex 20, France ; Ecole Centrale Marseille, 38 rue Joliot Curie, 13451 Marseille Cedex 20, France.

The synthesis of a conformal poly(3,4-ethylenedioxythiophene) (PEDOT) layer on Si nanowires was demonstrated using a pulsed electrodeposition technique. N-type Si nanowire (SiNWs) arrays were synthesized using an electroless metal-assisted chemical etching technique. The dependence of the SiNW reflection on the concentration of the AgNO3 solution was identified. A reflection of less than 2% over the entire visible spectral range was obtained for these structures, evidencing their excellent antireflective properties. The etched SiNWs nanostructures can be further modified by using a tapering technique, which further preserves the strong light trapping effect. P-type PEDOT was grown on these SiNWs using electrochemical methods. Since the polymerization reaction is a very fast process with regards to monomer diffusion along the SiNW, the conformal deposition by classical, fixed potential deposition was not favored. Instead, the core-shell heterojunction structure was finally achieved by a pulsed deposition method. An extremely large shunt resistance was exhibited and determined to be related to the diffusion conditions occurring during polymerization.
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http://dx.doi.org/10.3762/bjnano.6.65DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4362025PMC
March 2015

Enhanced electrochemical performance of Lithium-ion batteries by conformal coating of polymer electrolyte.

Nanoscale Res Lett 2014 2;9(1):544. Epub 2014 Oct 2.

Aix-Marseille Université, CNRS, LP3 UMR 7341, F-13288, Marseille Cedex 9, France ; Aix-Marseille Université, CNRS, MADIREL UMR 7246, F-13397, Marseille Cedex 20, France.

This work reports the conformal coating of poly(poly(ethylene glycol) methyl ether methacrylate) (P(MePEGMA)) polymer electrolyte on highly organized titania nanotubes (TiO2nts) fabricated by electrochemical anodization of Ti foil. The conformal coating was achieved by electropolymerization using cyclic voltammetry technique. The characterization of the polymer electrolyte by proton nuclear magnetic resonance ((1)H NMR) and size-exclusion chromatography (SEC) shows the formation of short polymer chains, mainly trimers. X-ray photoelectron spectroscopy (XPS) results confirm the presence of the polymer and LiTFSI salt. The galvanostatic tests at 1C show that the performance of the half cell against metallic Li foil is improved by 33% when TiO2nts are conformally coated with the polymer electrolyte.
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http://dx.doi.org/10.1186/1556-276X-9-544DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4194452PMC
October 2014

Three-dimensional self-supported metal oxides for advanced energy storage.

Adv Mater 2014 Jun 2;26(21):3368-97. Epub 2014 Apr 2.

Aix-Marseille University, CNRS, LP3 Laboratory, UMR 7341, 13288, Marseille, France.

The miniaturization of power sources aimed at integration into micro- and nano-electronic devices is a big challenge. To ensure the future development of fully autonomous on-board systems, electrodes based on self-supported 3D nanostructured metal oxides have become increasingly important, and their impact is particularly significant when considering the miniaturization of energy storage systems. This review describes recent advances in the development of self-supported 3D nanostructured metal oxides as electrodes for innovative power sources, particularly Li-ion batteries and electrochemical supercapacitors. Current strategies for the design and morphology control of self-supported electrodes fabricated using template, lithography, anodization and self-organized solution techniques are outlined along with different efforts to improve the storage capacity, rate capability, and cyclability.
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http://dx.doi.org/10.1002/adma.201306126DOI Listing
June 2014

Electrochemical fabrication and properties of highly ordered Fe-doped TiO2 nanotubes.

Chemphyschem 2012 Nov 28;13(16):3707-13. Epub 2012 Aug 28.

Aix Marseille University, CNRS, LP UMR, Marseille, France.

Highly-ordered Fe-doped TiO(2) nanotubes (TiO(2)nts) were fabricated by anodization of co-sputtered Ti-Fe thin films in a glycerol electrolyte containing NH(4)F. The as-sputtered Ti-Fe thin films correspond to a solid solution of Ti and Fe according to X-ray diffraction. The Fe-doped TiO(2)nts were studied in terms of composition, morphology and structure. The characterization included scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, UV/Vis spectroscopy, X-ray photoelectron spectroscopy and Mott-Schottky analysis. As a result of the Fe doping, an indirect bandgap of 3.0 eV was estimated using Tauc's plot, and this substantial red-shift extends its photoresponse to visible light. From the Mott-Schottky analysis, the flat-band potential (E(fb)) and the charge carrier concentration (N(D)) were determined to be -0.95 V vs Ag/AgCl and 5.0×10(19) cm(-3) respectively for the Fe-doped TiO(2)nts, whilst for the undoped TiO(2)nts, E(fb) of -0.85 V vs Ag/AgCl and N(D) of 6.5×10(19) cm(-3) were obtained.
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http://dx.doi.org/10.1002/cphc.201200406DOI Listing
November 2012

Highly conformal electrodeposition of copolymer electrolytes into titania nanotubes for 3D Li-ion batteries.

Nanoscale Res Lett 2012 Jun 27;7(1):349. Epub 2012 Jun 27.

Aix Marseille Université, CNRS, Chemistry of Materials Research Group LP3 UMR 7341, Marseille, F-13288, France.

The highly conformal electrodeposition of a copolymer electrolyte (PMMA-PEO) into self-organized titania nanotubes (TiO2nt) is reported. The morphological analysis carried out by scanning electron microscopy and transmission electron microscopy evidenced the formation of a 3D nanostructure consisting of a copolymer-embedded TiO2nt. The thickness of the copolymer layer can be accurately controlled by monitoring the electropolymerization parameters. X-ray photoelectron spectroscopy measurements confirmed that bis(trifluoromethanesulfone)imide salt was successfully incorporated into the copolymer electrolyte during the deposition process. These results are crucial to fabricate a 3D Li-ion power source at the micrometer scale using TiO2nt as the negative electrode.
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http://dx.doi.org/10.1186/1556-276X-7-349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3536562PMC
June 2012

Durability of sulfonated aromatic polymers for proton-exchange-membrane fuel cells.

ChemSusChem 2011 Nov 18;4(11):1526-36. Epub 2011 Oct 18.

Université de Provence-CNRS, UMR 6264: Laboratoire Chimie Provence, Marseille, France.

As a key component of proton-exchange-membrane fuel cells (PEMFCs), proton-exchange membranes (PEMs) must continuously withstand very harsh environments during long-term fuel cell operations. With the coming commercialization of PEMFCs, investigations into the durability and degradation of PEMs are becoming more and more urgent and interesting. Herein, various recent attempts and achievements to improve the durability of sulfonated aromatic polymers (SAPs) are reviewed and some further developments are predicted. Extensive investigations into inexpensive SAPs as alternative electrolyte membranes include modification of available polymer materials; design, synthesis, and optimization of new macromolecules; durability testing; and exploring the degradation mechanisms.
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http://dx.doi.org/10.1002/cssc.201000415DOI Listing
November 2011

EXAFS study of dopant ions with different charges in nanocrystalline anatase: evidence for space-charge segregation of acceptor ions.

Chemphyschem 2009 Jun;10(8):1238-46

Université de Provence-CNRS, UMR 6264: Laboratoire Chimie Provence, Centre St Jérôme, 13397 Marseille Cedex 20, France.

Nanocrystalline TiO(2) (anatase) is an essential oxide for environment and energy applications. A combination of EXAFS spectroscopy and DFT calculations on a series of dopants with quite similar ion radius, but increasing ion charge, show boundary space charge segregation of acceptor cations. The picture illustrates the Fourier-transformed EXAFS spectrum for Sn(4+)-doped TiO(2).A series of dopants, including acceptor ions (Zn(2+), Y(3+)), isovalent ions (Zr(4+), Sn(4+)) as well as a donor ion (Nb(5+)), were studied by EXAFS spectroscopy in nanocrystalline TiO(2) anatase powders and nanoceramics. Similar results were found for nanocrystalline powders and nanocrystalline ceramics, made by hot-pressing the powders. Boundary segregation was observed for the acceptor ions yttrium and zinc, whereas tin, zirconium and niobium ions were placed on substitutional bulk sites and did not segregate, whatever their concentration. These results can be interpreted based on defect thermodynamics, in the framework of a space charge segregation model with positive boundary core, due to excess oxide ion vacancies, and negative space charge regions, where ionized acceptors are segregated.
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http://dx.doi.org/10.1002/cphc.200800806DOI Listing
June 2009

Analysis of temperature-promoted and solvent-assisted cross-linking in sulfonated poly(ether ether ketone) (SPEEK) proton-conducting membranes.

J Phys Chem B 2009 May;113(21):7505-12

Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Roma, Italy.

Sulfonated poly(ether ether ketone) (SPEEK) membranes were thermally treated at temperatures between 120 and 160 degrees C. Water uptake measured at different relative humidity values or by full immersion in water between 25 and 145 degrees C was found to depend very strongly on previous thermal treatment and casting solvent. Water-uptake coefficient values as low as 10-15 even upon immersion in water at 100 degrees C were obtained with membranes treated at 160 degrees C. This effect is related to cross-linking by SO2 bridges between macromolecular chains. An important role is also played by the casting solvent: among the investigated solvents, dimethylsulfoxide (DMSO) gave the best results. A chemical kinetics model is outlined that permits the estimation of the relevant kinetic parameters, especially the activation energy of the cross-linking reaction, which was found to be about 60 kJ/mol. These results are of significant importance for the improvement of proton-exchange membrane fuel cells.
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http://dx.doi.org/10.1021/jp9006679DOI Listing
May 2009

Electrochemical fabrication of Sn nanowires on titania nanotube guide layers.

Nanotechnology 2008 May 14;19(20):205601. Epub 2008 Apr 14.

University of Aix-Marseille I, II, III-CNRS, UMR 6264: Laboratoire Chimie Provence, Electrochemistry of Materials Research Group, Centre Saint Jérôme, F-13397 Marseille Cedex 20, France.

We describe a novel approach for the fabrication of tailored nanowires using a two-step electrochemical process. It is demonstrated that self-organized TiO(2) nanotubes can be used to activate and guide the electrochemical growth of Sn crystallites, leading to the formation of vertical features with a high aspect ratio. We show that the dimensions and the density of Sn crystallites depend on the electrodeposition parameters.
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http://dx.doi.org/10.1088/0957-4484/19/20/205601DOI Listing
May 2008

Solid-state electrolysis in CuBr thin films: observation and modelling of fractal growth.

Chemphyschem 2002 Jan;3(1):107-10

Laboratoire Matériaux Divisés, Revêtements, Electrocéramiques (MADIREL) UMR 6121, Université de Provence-CNRS, Centre St. Charles, Case 26, 13331 Marseille, France.

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http://dx.doi.org/10.1002/1439-7641(20020118)3:1<107::AID-CPHC107>3.0.CO;2-2DOI Listing
January 2002

Zeolite Synthesis by the High-Pressure Hydrothermal Method: Synthesis of Natural 6-Ring Zeolites with Different Void Systems.

Angew Chem Int Ed Engl 2001 Oct;40(20):3831-3833

Institut für Mineralogie Freie Universität Berlin Takustrasse 6, 14195 Berlin (Germany).

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http://dx.doi.org/10.1002/1521-3773(20011015)40:20<3831::aid-anie3831>3.0.co;2-zDOI Listing
October 2001
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