Electrochemical charging of carbon nanotubes modified with polyoxometallates monolayers

Magdalena Skunik ,  Paweł J. Kulesza ,  Malgorzata Chojak ,  Krzysztof Miecznikowski ,  Beata Baranowska 

Warsaw University, Faculty of Chemistry, Pasteura 1, Warszawa 02-093, Poland

Abstract

We demonstrate here a novel type of electrode material for electrochemical capacitors (ECs) with improved capacitance properties that is prepared in a form of carbon nanotubes (CNTs) modified with ultra-thin films of a Keggin type polyoxometallate (POM), namely phosphododecamolybdic acid, H3PMo12O40 (PMo12). Such features of POMs as their well-defined structures, the ability to undergo fast and reversible redox reactions, specific photoelectrochemical properties made them model systems not only for nanometric metal (e.g. Mo or W) oxide particles but also for inorganic functional materials of potential utility in electrocatalysis, molecular electronics, sensing and in energy storage applications. Here we refer to such attractive properties of PMo12 as its ability to adsorb irreversibly in forms of monolayers on solid surfaces as platinum, gold and carbon. It is notworthy that monolayers of such Keggin type POM’s are formed not only on solid electrodes but also on metal (e.g. Pt) nanoparticles, as well as on carbon particles (carbon black) and CNTs. In this communication, we explore the possibility of modification of CNT surfaces through adsorption of the anionic PMo12 monolayers. It is apparent from three distinct test experiments (based on cyclic voltammetry, galavanostatic charging-discharging and AC impedance) that capacitors utilizing H3PMo12O40-modified carbon nanotubes are characterized by higher specific capacitances and energy densities than systems built from bare (pristine) carbon nanotubes. It is reasonable to expect that multi-walled CNTs modified through the interfacial adsorption of Keggin-type polyoxometallate (PMo12) monolayers seem to exhibit both double-layer type capacitive effects as well as pseudo-capacitance properties originating from the fast and reversible multi-electron redox reactions of PMo12 that significantly contribute to the observed overall capacitance. When it comes to the determination of specific capacitance, a good correlation between such three electrochemical methods as cyclic voltammetry, galvanostatic charging-discharging and AC impedance has been found.

 

Related papers
  1. Development of multifunctional bioelectrocatalytic films for oxidation of ethanol   
  2. Integrated carbon nanotube based mediating systems for bioelectrocatalysis: application to oxygen reduction and glucose oxidation
  3. Preparation of copper hexacyanoferrate multilayer films modified with 4-(Pyrrole-1-yl) benzoic acid on glassy carbon electrode.
  4. Development of electrocatalytic materials based on the mixed addenda Dawson heteropolyanion and conducting polymers
  5. Development of novel bioelectrocatalytic systems through controlled combination of multiwalled carbon nanotubes, redox mediators and enzymes
  6. Oxidation of glucose at nanostructured composite bioelectrocatalytic systems
  7. Application of Inorganic Redox - Conducting Solids As Charge Relays in Dye-Sensitized Solar Cell
  8. Bi-functional electrocatalytic systems for oxygen reduction in acid medium
  9. Incorporation of RuSex/C within nanostructural Ir matrices to enhance oxygen reduction
  10. Enzymatic carbon nanotube based composite electrodes for dioxygen reduction
  11. Multifunctional bio-electrocatalytic systems for reduction of oxygen and hydrogen peroxide
  12. Electrocatalysis and Bioelectrocatalysis at Network Films of Metal Nanoparticles and Carbon Nanostructures
  13. Bioelectrocatalytic dioxygen reduction at carbon nanotubes – silicate composite film modified electrode
  14. Development and characterization of bioelectrocatalytic systems for oxygen reduction
  15. Activation of Methanol-Tolerant Carbon-Supported RuSex Electrocatalytic Nanoparticles Towards More Efficient Oxygen Reduction
  16. Electrocatalysis and bioelectrocatalysis and nanostructured composite films
  17. New strategies in the electroctalytic reduction of oxygen for fuel and biofuel cells
  18. Polyoxometallate-modified conducting polymer linked Pt nanoparticles as bifunctional electrocatalysts for bromate reduction
  19. Network Films of Conducting Polymer Linked and Polymeatallate Stabilized Platinum Nanoparticles

Presentation: Poster at SMCBS'2007 International Workshop, by Magdalena Skunik
See On-line Journal of SMCBS'2007 International Workshop

Submitted: 2007-09-24 15:54
Revised:   2009-06-07 00:44