Synthesis and photoelectrochemical behaviour of hydrogenated titania nanotubes modified with conducting polymer infiltrated by redox active network

Abstract

In this work, we show preparation of ordered inorganic-organic composite electrode material where hydrogenated titania nanotubes H-TiO2 with tubularly developed surface modified with poly(3,4-ethylenedioxythiophene) matrix permeated by Prussian Blue (PB) inorganic redox network in order to reach highly photoactive heterojunction. The polymer deposition was realized via two subsequent processes covering: i) potentiostatic polymerization carried out at H-TiO2 electrode immersed in solution of EDOT monomer and Fe[(CN)6]3−/4− ions and ii) cyclic voltammetry routs in iron chloride solution. The inorganic-organic hybrids were characterized by scanning electron microscopy, spectroscopic techniques (UV-Vis, Raman, Fourier transform infrared and X-ray photoelectron spectroscopy) and using electrochemical methods. Cyclic voltammetry curves registered for inorganic-organic composite exhibit clear reversible reduction/oxidation peaks attributed to the high spin (HS) FeII/FeIII redox activity when low spin (LS) FeII/FeIII redox activity overlaps with the water oxidation process. The LS FeII/FeIII redox center of PB imbedded in pEDOT matrix plays crucial role in high increase of photocurrent recorded for composite H-TiO2NTs/pEDOT:BP that is 3.7 times higher in comparison to photocurrent measured for H-TiO2NT at anodic polarization of electrode.