Quartz crystal microbalance monitoring of density changes in mesoporous TiO2 phytate films during redox and ion exchange processes

Katy J. McKenzie, Frank Marken, Xin Gao, Shik Chi Tsang, Kin Y. Tam

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Nanofilm deposits of TiO2 nanoparticle phytates are formed on gold electrode surfaces by 'directed assembly' methods. Alternate exposure of a 3-mercapto-propionic acid modified gold surface to (i) a TiO2 sol and (ii) an aqueous phytic acid solution (pH 3) results in layer-by-layer formation of a mesoporous film. Ru(NH33+6 is shown to strongly adsorb/accumulate into the mesoporous structure whilst remaining electrochemically active. Scanning the electrode potential into a sufficiently negative potential range allows the Ru(NH3)3+6 complex to be reduced to Ru(NH3)2+6 which undergoes immediate desorption. When applied to a gold coated quartz crystal microbalance (QCM) sensor, electrochemically driven adsorption and desorption processes in the mesoporous structure become directly detectable as a frequency response, which corresponds directly to a mass or density change in the membrane. The frequency response (at least for thin films) is proportional to the thickness of the mass-responsive film, which suggests good mechanical coupling between electrode and film. Based on this observation, a method for the amplified QCM detection of small mass/density changes is proposed by conducting measurements in rigid mesoporous structures.

Original languageEnglish
Pages (from-to)286-291
Number of pages6
JournalElectrochemistry Communications
Issue number4
Publication statusPublished - 1 Apr 2003


  • Adsorption
  • Bioinorganic composite materials
  • Density response
  • Directed assembly
  • Nanoparticles
  • Phytic acid
  • Quartz crystal microbalance
  • TiO
  • Voltammetry

ASJC Scopus subject areas

  • Electrochemistry

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