In situ FTIR studies on prussian blue (PB)-, polyaniline (PAn)- and inner PB|outer PAn film-modified electrodes

Abstract

The electrochemical properties of the Pt electrodes modified with Prussian blue (PB), polyaniline (PAn) and inner PB|outer PAn films have been examined using in situ Fourier transform infrared spectroscopy. At the PB-modified electrode, two strong peaks were observed at 2040 and 2110cm −1 owing to the bridging CN ligand in the PB structure. Three absorption bands appeared at 2780, 1015, and 982 cm −1 by stepping the potential to more positive than +0.2V vs. Ag|AgCl|l M KCl, which were assigned to various vibrational modes of water molecules coordinated to the high-spin Fe 3+ ion of PB. It is suggested that doping or undoping of potassium ions during the polarization of the Pt|PB electrode is accompanied by expulsion or introduction of water molecules respectively. At the PB|PAn-modified electrode, the absorption spectrum of PAn in the vibrational region was searcely affected by the underlying PB. The spectral intensity of the PAn on Pt|PB was much larger than that of the PAn on Pt, which is brought about by the K + ions being more effective as the charge-compensating ions in the PB|PAn film.