Stability of Prussian Blue-polypyrrole (PB/PPy) composite films synthesized via one-step redox-reaction procedure

Composite materials of Prussian Blue-polypyrrole (PB/PPy) were obtained via chemical redox process in mixed solution of iron (III), hexacyanoferrate (III), and pyrrole with chloride or nitrate supporting electrolyte. Synthesized composites in the form of a sedimented powder, or a film on the surface of Pt and ITO-coated glass, were characterized by various physical and electrochemical methods. Stability of PB/PPy films on Pt substrate was tested in electrocatalytic reaction of hydrogen peroxide reduction in weakly acidic medium (pH 6) as well as on ITO-coated glass substrate via electrochromic (spectroelectrochemical) measurements. Stability period of the amperometric response in 1 mM H2O2 solution for films on Pt substrate synthesized in chloride media is 20 times longer than that of pure PB films obtained electrochemically in potentiostatic mode. Morphology of PB/PPy films has been found to depend on the composition of supporting electrolyte. Synthesis of PB/PPy composites in nitrate electrolyte leads to formation of a high-quality morphology, whereas PB/PPy films obtained in chloride solutions are cracked. In conformity with this observation, the stability period of the H2O2 electroreduction for nitrate-synthesized films on Pt substrate was about 150 min, i.e., 80 times longer than that of pure Prussian Blue films without polymeric support and four times longer than that of chloride-synthesized films. Stability of the electrochromic response of PB/PPy films formed in nitrate media is 10 times higher than pure PB film.