A study of electrochemically grown prussian blue films using Fourier-transform infra-red spectroscopy

Abstract

The electrochemical cycling of films of Prussian Blue (PB), deposited by electroreduction onto Pt, have been studied by in situ Fourier-transform i.r. spectroscopy under potential control. The results are compared with those obtained earlier using ellipsometry. The behaviour of the films can be understood in terms of a two-phase model, in agreement with the ellipsometric results. The outer, porous film, present in variable amount, is found to be largely ‘insoluble’ PB whereas the inner film, which constitutes the majority of material present in the experiments, changes to ‘soluble’ PB on repeated reductive cycling. The two phases have quite different i.r. spectra, and their relative intensities change as a function of cycling, in agreement with earlier work. The process of oxidation to Prussian Yellow reveals the kinetic sluggishness of the outer layer particularly clearly.