Photoelectrochemical Studies on Inorganic/Organic Aqueous Nano-Suspensions Made by TiO2/Poly Neutral Red Assembly

Abstract

An inorganic/organic interface (IOI) consisting of TiO2/polyNeutral Red(PNR) was subjected to photoelectrochemical studies in both aqueous nano-suspensions and in thin solid forms. The effects caused by PNR modifier on the photoelectrochemical behaviour of the IOI were investigated using [Fe(CN)6]4- as a photoactive hydrated electron donor agent. Results show that the adsorption process of [Fe(CN)6]3- (photolysis product) controls the photo-activity outcomes of IOI assemblies. TiO2/PNR shows lower heterogeneous photochemical response than native TiO2 in a short photolysis time. At longer photolysis times the IOI show a photo activity greater than that of native TiO2. TiO2 /PNR nanoparticles adsorb more [Fe(CN)6]3- in a very steady adsorption /desorption process than the unmodified particles. The interface activities were explained by analysing the IOI junction characteristics, such as electron affinity, work function and hole/electron barrier heights. At TiO2/PNR a strong hybridization between electrons-like and hole-like sub band states in close vicinity to the Fermi energy are developed. The aqueous nano-systems retained moderate stability as indicated by the reproducibility of their photo catalytic activities. Both [Fe(CN)6]4- and PNR contributed to the stability of native TiO2 surfaces.