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Mediator enhanced water oxidation using Rb4[Ru II(bpy)3]5[{RuIII 4O 4(OH)2(H2O)4}(γ-SiW 10O36)2] film modified electrodes

Journal Article


Abstract


  • The water insoluble complex Rb4[RuII(bpy) 3]5[{RuIII 4O4(OH) 2(H2O)4}(γ-SiW10O 36)2], ([RuIIbpy]5[Ru III 4POM]), was synthesized from Rb8K 2[{RuIV 4O4(OH)2(H 2O)4}(γ-SiW10O36) 2] and used for electrocatalytic water oxidation under both thin- and thick-film electrode conditions. Results demonstrate that the [Ru IIbpy]5[RuIII 4POM] modified electrode enables efficient water oxidation to be achieved at neutral pH using thin-film conditions, with [Ru(bpy)3]3+([Ru IIIbpy]) acting as the electron transfer mediator and [Ru V 4POM] as the species releasing O2. The rotating ring disc electrode (RRDE) method was used to quantitatively determine the turnover frequency (TOF) of the catalyst, and a value of 0.35 s-1 was obtained at a low overpotential of 0.49 V (1.10 V vs Ag/AgCl) at pH 7.0. The postulated mechanism for the mediator enhanced catalytic water process in a pH 7 buffer containing 0.1 M LiClO4 as an additional electrolyte includes the following reactions (ion transfer for maintaining charge neutrality is omitted for simplicity): [RuIIbpy]5[Ru III 4POM] → [RuIIIbpy]5[Ru V 4POM] + 13 e- and [RuIIIbpy] 5[RuV 4POM] + 2H2O → [Ru IIIbpy]5[RuIV 4POM] + O2 + 4H+. The voltammetry of related water insoluble [Ru IIbpy]2[S2M18O62] (M = W and Mo) and [FeIIPhen]x[RuIII 4POM] materials has also been studied, and the lack of electrocatalytic water oxidation in these cases supports the hypothesis that [RuIIIbpy] is the electron transfer mediator and [RuV 4POM] is the species responsible for oxygen evolution. © 2014 American Chemical Society.

UOW Authors


  •   Guo, Si Xuan. (external author)
  •   Lee, Chong Yong
  •   Zhang, Jie (external author)
  •   Bond, Alan M. (external author)
  •   Geletii, Yurii V. (external author)
  •   Hill, Craig L. (external author)

Publication Date


  • 2014

Citation


  • Guo, S. Xuan., Lee, C., Zhang, J., Bond, A. M., Geletii, Y. V. & Hill, C. L. (2014). Mediator enhanced water oxidation using Rb4[Ru II(bpy)3]5[{RuIII 4O 4(OH)2(H2O)4}(γ-SiW 10O36)2] film modified electrodes. Inorganic Chemistry: including bioinorganic chemistry, 53 (14), 7561-7570.

Scopus Eid


  • 2-s2.0-84904651076

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/4836

Has Global Citation Frequency


Number Of Pages


  • 9

Start Page


  • 7561

End Page


  • 7570

Volume


  • 53

Issue


  • 14

Place Of Publication


  • United States

Abstract


  • The water insoluble complex Rb4[RuII(bpy) 3]5[{RuIII 4O4(OH) 2(H2O)4}(γ-SiW10O 36)2], ([RuIIbpy]5[Ru III 4POM]), was synthesized from Rb8K 2[{RuIV 4O4(OH)2(H 2O)4}(γ-SiW10O36) 2] and used for electrocatalytic water oxidation under both thin- and thick-film electrode conditions. Results demonstrate that the [Ru IIbpy]5[RuIII 4POM] modified electrode enables efficient water oxidation to be achieved at neutral pH using thin-film conditions, with [Ru(bpy)3]3+([Ru IIIbpy]) acting as the electron transfer mediator and [Ru V 4POM] as the species releasing O2. The rotating ring disc electrode (RRDE) method was used to quantitatively determine the turnover frequency (TOF) of the catalyst, and a value of 0.35 s-1 was obtained at a low overpotential of 0.49 V (1.10 V vs Ag/AgCl) at pH 7.0. The postulated mechanism for the mediator enhanced catalytic water process in a pH 7 buffer containing 0.1 M LiClO4 as an additional electrolyte includes the following reactions (ion transfer for maintaining charge neutrality is omitted for simplicity): [RuIIbpy]5[Ru III 4POM] → [RuIIIbpy]5[Ru V 4POM] + 13 e- and [RuIIIbpy] 5[RuV 4POM] + 2H2O → [Ru IIIbpy]5[RuIV 4POM] + O2 + 4H+. The voltammetry of related water insoluble [Ru IIbpy]2[S2M18O62] (M = W and Mo) and [FeIIPhen]x[RuIII 4POM] materials has also been studied, and the lack of electrocatalytic water oxidation in these cases supports the hypothesis that [RuIIIbpy] is the electron transfer mediator and [RuV 4POM] is the species responsible for oxygen evolution. © 2014 American Chemical Society.

UOW Authors


  •   Guo, Si Xuan. (external author)
  •   Lee, Chong Yong
  •   Zhang, Jie (external author)
  •   Bond, Alan M. (external author)
  •   Geletii, Yurii V. (external author)
  •   Hill, Craig L. (external author)

Publication Date


  • 2014

Citation


  • Guo, S. Xuan., Lee, C., Zhang, J., Bond, A. M., Geletii, Y. V. & Hill, C. L. (2014). Mediator enhanced water oxidation using Rb4[Ru II(bpy)3]5[{RuIII 4O 4(OH)2(H2O)4}(γ-SiW 10O36)2] film modified electrodes. Inorganic Chemistry: including bioinorganic chemistry, 53 (14), 7561-7570.

Scopus Eid


  • 2-s2.0-84904651076

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/4836

Has Global Citation Frequency


Number Of Pages


  • 9

Start Page


  • 7561

End Page


  • 7570

Volume


  • 53

Issue


  • 14

Place Of Publication


  • United States