Electrochemical investigations into ferrocenylphosphonic acid functionalized mesostructured porous nanocrystalline titanium oxide films

Abstract

Titanium dioxide nanocrystalline mesoporous thin films were prepared by the evaporation induced self assembly process onto a SnO₂–F (FTO) electrode and post-functionalized by ferrocenylphosphonic acid as a grafted electrochemical probe. We showed that the pseudo-diffusive electron hopping between the redox species is related to the specific order of the TiO₂ layer mesoporosity. The electrochemical measurements exhibit a very unusual behavior for a modified electrode as far as the slopes of the log Ivs. log t curves are concerned, featuring a charge transfer occurring in a strongly anisotropic medium. The electronic diffusion coefficient values have been determined and fit well with results obtained for similar materials using soluble redox probes. This study demonstrates that efficient charge transfer can be driven when organic components are grafted onto the porous surface of mesotructured TiO₂ semiconducting films.