Electrode Kinetics of the Redox Reaction of Tris(2,2′-bipyridine) nickel Complexes in an Ionic Liquid

Yasushi Katayama, Yuichi Toshimitsu, Takashi Miura

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Electrode reaction of tris(2,2′-bipyridine)nickel complexes, [Ni(bpy)3]3+ and [Ni(bpy)3]2+, was investigated in an aprotic ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) using AC impedance spectroscopy. The formal potential of [Ni(bpy)3]3+/2+ was 1.37 V vs. ferrocene/ferrocenium at 25 °C. The diffusion coefficients of [Ni(bpy) 3]3+ and [Ni(bpy)3]2+ at 25°C were 4.2 and 7.0 × 10-8 cm2 s-1, respectively, which are close to those of [M(bpy)3]3+ and [M(bpy)3]2+ (M = Ru and Fe) due to the similarity in the charge densities. The activation energies for the diffusion coefficients were close to that for the viscosity of the ionic liquid, indicating the viscosity is a major factor that determine the diffusion of the complexes. The rate constant of [Ni(bpy)3]3+/2+ was 8.3 × 10-6 cm s-1, which is smaller by two orders of magnitude than those for [Ru(bpy)3]3+/2+ and [Fe(bpy)3]3+/2+, reflecting the slow electron transfer caused by participation of the anti-bonding molecular orbital in the redox reaction. The apparent activation energy for the rate constant of [Ni(bpy)3]3+/2+ is considered determined not only by the activation energy for the viscosity but also by the reorganization energy, of which the inner component is larger than those in [Ru(bpy)3]3+/2+ and [Fe(bpy)3] 3+/2+.

Original languageEnglish
Pages (from-to)36-41
Number of pages6
JournalElectrochimica Acta
Volume131
DOIs
Publication statusPublished - 2014 Jun 10

Fingerprint

Ionic Liquids
Redox reactions
Nickel
Ionic liquids
Activation energy
Viscosity
Electrodes
Kinetics
Rate constants
Molecular orbitals
Charge density
Amides
Spectroscopy
Electrons
tris(2,2'-bipyridine)ruthenium II

Keywords

  • AC impedance
  • Electrode kinetics
  • Ionic liquid
  • Tris(2;2′-bipyridine)nickel complex

ASJC Scopus subject areas

  • Electrochemistry
  • Chemical Engineering(all)

Cite this

Electrode Kinetics of the Redox Reaction of Tris(2,2′-bipyridine) nickel Complexes in an Ionic Liquid. / Katayama, Yasushi; Toshimitsu, Yuichi; Miura, Takashi.

In: Electrochimica Acta, Vol. 131, 10.06.2014, p. 36-41.

Research output: Contribution to journalArticle

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