Chemical and electrochemical modification of carbon
Chemical modification of electrodes by adsorption or grafting allows for the control of the kinetics and the selectivity of electron transfer processes. The resulting modified electrodes might prove useful for application in sensors, catalysis and electrocatalysis.
We and others have recently shown that carbon based electrodes could be electrochemically and chemically modified by electrochemical reduction of diazonium cations according to:
<-Carbon, silicon, metal
This modification procedure was also extended to silicon and metallic electrodes. The properties of the resulting modified carbon electrodes can be tailored by careful selection of the R group. Thus, hydrophilic (COOH), electroactive (NO2) and hydrophobic (CF3) surfaces can be generated with such terminal groups. We have also demonstrated that at lower pH when the carboxy group are protonated, ferricyanide gave rise a well-defined cyclic voltammogram and confirms that electrical communication occurs between the redox species and the carbon electrode. We have also shown that carboxy phenyl functionalized carbon electrodes would be suitable for recovery of metallic ions present in an aqueous solution. As a natural extension of this work metallic particles were also recently generated at these surfaces.
This research project currently focuses on the chemical and electrochemical modification as well as the characterization of substituted phenyl modified carbon electrodes and the use of these modified electrodes for electrocatalysis and sensors. The modification of gold is also investigated.
Electrochemical reduction of nitrate
The elimination of nitrate from water effluents, underground water sources and in industrial processes generating high concentration of nitrate is an important problem that has attracted a lot of interest recently due to the health hazard associated with nitrate. Consequently, several non electrochemical and electrochemical approaches have been suggested in the literature for the removal of nitrate.
The long-term objective of the research in this area would be to transform nitrate into harmless nitrogen gas. For the purpose of developing electrode materials that could be used in industrial applications, metal and metal oxides offer attractive alternatives since these electrode materials are already being used in several other electrochemical applications.
This project is performed in collaboration with Professor Lionel Roué from INRS-EMT (E-mail: roue@inrs-emt.uquebec.ca).
Modification of membrane
The treatment of industrial effluents that is required to minimize the contamination of the environment upon disposal and/or to recover valuable chemicals concerns several industries. Some of these industrial wastes consist of spent acids containing heavy metals that are generated by a number of industrial processes, such as steel treatment, metal refining (zinc and copper), pigment production (titanium), surface treatment (chromium and nickel) and chemical production (catalysis). Such acid wastes can be treated by neutralization with a base, distillation, evaporation and pyrolysis but the environmental consequences related to the stocking of the resulting toxic solid wastes remain an important issue. Thus, the development of other technological solutions for the treatment of industrial spent acids become evident. Among the possible alternatives, electrodialysis is an attractive technique because it allows the purification and reconcentration of acid and also the production of lower amounts of salt effluents or sludges.
This research project deals with the surface modification of commercial cation-exchange membrane with a positively charged layer to enhance its selectivity towards protons with respect to divalent cations in electrodialysis processes.
The usefulness of such modified membrane to minimize methanol cross-over in direct methanol fuel cell is also currently investigated in our laboratory.
Electrochemical supercapacitors
Supercapacitors are currently extensively studied as possible auxiliary energy storage devices to be used with rechargeable batteries. They combine the advantages of both dielectric capacitors, which can deliver high power within very small period and rechargeable batteries which store high energy. Active electrode materials for electrochemical supercapacitors consist of carbon, conducting polymers and metal oxides. The two last kind of systems involve pseudo faradaic reactions unlike carbon systems which use the double layer capacitance arising from the separation of charge at the interface between the solid electrode and an electrolyte.
A group of materials currently investigated are low-cost metal oxides such as MnO 2 and Fe 3O 4. Low cost oxides are prepared by a variety of techniques that enable the. Finally, various carbon materials are also tested as electrode materials for aqueous electrochemical capacitors.
The objectives of this project consist in the electrochemical and chemical synthesis of the materials and their characterization by spectroscopic and electrochemical techniques. We are currently developing hybrid system, which consists of a metal oxide as the positive electrode and either a carbon or another metal oxide electrode as the negative. Finally, electrochemical supercapacitors assembled with these materials as active electrode materials are also characterized and their charge storage (discharge capacity, energy and power densities) performance was also evaluated.
This project is done in collaboration with Professor Thierry Brousse (École Polytechnique de l'Université de Nantes ). E-mail: thierry.brousse@polytech.univ-nantes.fr
(2005)
J. Marwan, T. Addou, and D. Bélanger (2005) "Functionalization of glassy carbon electrodes with metal-based species" Chem. Mater., accepted, March 9.
M. Toupin, D. Bélanger I, Hill and D. Quinn (2005) "Performance of experimental carbon blacks in aqueous supercapacitors" J. Power Sources, 140, 203-210.
G. Chamoulaud and D. Bélanger (2004) " Modification of ion-exchange membrane used for separation of protons and metallic cations and characterization of the membrane by current–voltage curves" J. Colloid Interface Sci ., 281, 179-187.
(2004)
M. Toupin, T. Brousse and D. Bélanger (2004) "Charge storage mechanism for MnO2 electrode used in aqueous electrochemical capacitor" Chem. Mater., 16, 3184-3190.
G. Chamoulaud and D. Bélanger (2004) "Chemical modification of the surface of a sulfonated membrane by formation of a sulfonamide bond" Langmuir, 20, 4989-4995.
T. Brousse, M. Toupin and D. Bélanger (2004) "A hybrid activated carbon-manganese dioxide capacitor using a mild aqueous electrolyte" J. Electrochem. Soc., 151, A614-A622.
O. Ghodbane, G. Chamoulaud and D. Bélanger (2004) "Chemical reactivity of 4-bromophenyl modified glassy carbon electrode" Electrochem. Commun., 6, 254-258.
(2003)
T. Brousse and D. Bélanger (2003) "An Hybrid Fe3O4-MnO2 Capacitor in Mild Aqueous Electrolyte" Electrochem. Solid-State Lett., 6, A244-A248.
M. D’Amours and D. Bélanger (2003) "Stability of substituted phenyl groups electrochemically grafted at carbon electrode surface" J. Phys. Chem. B, 107, 4811-4817.
D. Villers, D. Jobin, C. Soucy, D. Cossement, R. Chahine, L. Breau and D. Bélanger (2003) "The Influence of the Range of Electroactivity and Capacitance of Conducting Polymers on the Performance of Carbon/Conducting Polymer Hybrid Supercapacitor" J. Electrochem. Soc., 150, A-747-A752.
M. De Koninck, T. Brousse and D. Bélanger (2003) "The electrochemical generation of ferrate at pressed iron powder electrode: Effect of different parameters" Electrochimica Acta, 48, 1425-1433.
M. De Koninck and D. Bélanger (2003) "The electrochemical generation of ferrate at pressed iron powder electrode: Comparison with a foil electrode" Electrochimica Acta, 48, 1435-1442.
S. Tan, A. Laforgue, and D. Bélanger (2003) "Characterization of a cation-exchange/polyaniline composite membrane" Langmuir, 19, 744-751.
(2002)
E. Naudin, P. Dabo, D. Guay and D. Bélanger (2002) "X-ray photoelectron spectroscopy studies of the electrochemically n-doped state of a conducting polymer" Synth. Met., 132, 71-79.
E. Naudin, H.A. Ho, L. Breau and D. Bélanger (2002) "Electrochemical polymerization and characterization of poly (3-(4-fluorophenyl)thiophene) in pure ionic liquids" J. Phys. Chem.B, 106, 10585-10593.
M. Toupin, T. Brousse and D. Bélanger (2002) "The influence of microstructure on the charge storage properties of chemically synthesized manganese dioxide" Chem. Mater., 14, 3946-3952.
S. Tan, V. Viau, D. Cugnod and D. Bélanger (2002) "Chemical modification of a sulfonated membrane with cationic polyaniline layer to improve its permselectivity" Electrochem. Solid-State Lett., 5, E55-E58.
E. Naudin, H.A. Ho, M.-A. Bonin, L. Breau and D. Bélanger (2002) "Preparation and characterization of 2,3-dimethyl-1-(4-thien-3-ylbenzyl)-1H-imidazol-3ium bis((trifluoromethyl)sulfonyl)imide" Macromolecules, 35, 4983-4987.
P. Soudan, J. Gaudet, D. Guay, D. Bélanger and R. Schulz (2002) "Electrochemical properties of ruthenium-based nanocrystalline materials as electrodes for supercapacitors" Chem. Mater., 14, 1210-1215.
(2001)
P. Soudan, H. A. Ho, L. Breau and D. Bélanger (2001) "Chemical synthesis and electrochemical properties of poly(cyano-substituted-diheteroarenethylene) as conducting polymers for electrochemical supercapacitors" J. Electrochem. Soc., 148, A775-A782.
P. Soudan, P. Lucas, H.A. Ho, D. Jobin, L. Breau and D. Bélanger (2001) "Synthesis, chemical polymerization and electrochemical properties of low band gap conducting polymers for use in supercapacitors" J. Mater. Chem., 11, 773-782.
E. Naudin, N. El Mehdi, C. Soucy, L. Breau and D. Bélanger (2001) "Poly(3-arylthiophenes): Syntheses of monomers and spectroscopic and electrochemical characterization of the corresponding monomers" Chem. Mater., 13, 634-642.
F. Fusalba, P. Gouérec, D. Villers and D. Bélanger (2001) "Electrochemical characterization of polyaniline in non-aqueous electrolyte and its evaluation as electrode material for electrochemical supercapacitors" J. Electrochem. Soc., 148, A1-A6.
(2000)
F. Fusalba, H. Anh Ho, L. Breau and D. Bélanger (2000) "Poly(cyano-substituted diheteroareneethylene as active electrode material for electrochemical supercapacitors" Chem. Mater., 12, 2581-2589.
D. Bélanger, X. Ren, J. Davey, F. Uribe and S. Gottesfeld (2000) "Characterization and long-term performance of polyanilinie based electrochemical capacitors" J. Electrochem. Soc., 147, 2923-2929.
P. Lucas, N. El Mehdi, H. Anh Ho, D. Bélanger and L. Breau (2000) “Expedient synthesis of symmetric aryl ketones and of ambient-temperature molten salts of imidazole” Synthesis, 9, 1253-1258.
P. Soudan, P. Lucas, L. Breau and D. Bélanger (2000) "Electrochemical modification of poly(3-(4-fluorophenyl)thiophene)" Langmuir, 16, 4362-4366.
F. Fusalba and D. Bélanger (2000) "Electrochemical characterization of polyaniline-molybdenum trisulfide electrode in non aqueous media", Electrochim. Acta (Special Issue on The QCM in Electrochemistry), 45, 3877-3883.
(1999)
F. Fusalba and D. Bélanger (1999) "Electropolymerization of polypyrrole and polyaniline-polypyrrole from organic acidic medium" J. Phys. Chem. B, 103, 9044-9054.
F. Fusalba, N. El Mehdi, L. Breau and D. Bélanger (1999) "Physicochemical and electrochemical characterization of polycyclopenta[2,1-b3,4-b’]ditiophen-4-one as an active electrode for electrochemical supercapacitors" Chem. Mater., 11, 2743-2753.
F. Fusalba and D. Bélanger (1999) "Chemical synthesis and characterization of polyaniline-molybdenum trisulfide composite", J.Mater. Res.,14, 1805-1813.
M. Vaillancourt, G. Fortier and D. Bélanger (1999) "Electrochemical and enzymatic studies of electron transfer mediation by ferrocene derivatives with Nafion-glucose oxidase electrodes" Electroanalysis, 11, 23-31.
B. Garcia, F. Roy et D. Bélanger (1999) "Electrochemical behavior of polypyrrole-molybdenum trisulfide-tetrathiomolybdate electrode in non aqueous media" J. Electrochem. Soc., 146, 226-231.