Morphology changes and mechanistic aspects of the electrochemically-induced reversible solid - Solid transformation of microcrystalline TCNQ into Co[TCNQ]2-based materials (TCNQ = 7,7,8,8-tetracyanoqujnodimethane)

Nafady, A, O'Mullane, A, Neufeld, A and Bond, A 2006, 'Morphology changes and mechanistic aspects of the electrochemically-induced reversible solid - Solid transformation of microcrystalline TCNQ into Co[TCNQ]2-based materials (TCNQ = 7,7,8,8-tetracyanoqujnodimethane)', Chemistry of Materials, vol. 18, no. 18, pp. 4375-4384.


Document type: Journal Article
Collection: Journal Articles

Title Morphology changes and mechanistic aspects of the electrochemically-induced reversible solid - Solid transformation of microcrystalline TCNQ into Co[TCNQ]2-based materials (TCNQ = 7,7,8,8-tetracyanoqujnodimethane)
Author(s) Nafady, A
O'Mullane, A
Neufeld, A
Bond, A
Year 2006
Journal name Chemistry of Materials
Volume number 18
Issue number 18
Start page 4375
End page 4384
Total pages 10
Publisher American Chemical Society
Abstract The chemically reversible solid-solid phase transformation of a TCNQ-modified glassy carbon, indium tin oxide, or metal electrode into Co[TCNQ]2(H2O)2 material in the presence of Co2+(aq) containing electrolytes has been induced and monitored electrochemically. Voltammetric data reveal that the TCNQ/ Co[TCNQ]2(H2O)2 interconversion process is independent of electrode material and identity of cobalt electrolyte anion. However, a marked dependence on electrolyte concentration, scan rate, and method of electrode modification (drop casting or mechanical attachment) is found. Cyclic voltammetric and double potential step chronoamperometric measurements confirm that formation of Co[TCNQ]2(H2O)2 occurs through a rate-determining nucleation and growth process that initially involves incorporation of Co2+(aq) ions into the reduced TCNQ crystal lattice at the TCNQ|electrode|electrolyte interface. Similarly, the reverse (oxidation) process, which involves transformation of solid Co[TCNQ]2(H2O)2 back to parent TCNQ crystals, also is controlled by nucleation-growth kinetics. The overall chemically reversible process that represents this transformation is described by the reaction: 2TCNQ(s)0 + 2e- + Co 2+(aq) +2H2O[Co(TCNQ)2(H 2O)2](s). Ex situ SEM images illustrated that this reversible TCNQ/Co[TCNQ]2(H2O)2 conversion process is accompanied by drastic size and morphology changes in the parent solid TCNQ. In addition, different sizes of needle-shaped nanorod/nanowire crystals of Co[TCNQ]2(H2O)2 are formed depending on the method of surface immobilization.
Subject Chemical Engineering not elsewhere classified
Copyright notice © 2006 American Chemical Society.
ISSN 0897-4756
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