Electrochemical and enhanced photoelectrochemical properties of a hybrid film composed of anionic sandwich-type heteropolyoxotungstate and cationic hemicyanine

Abstract

A new inorganic–organic hybrid film, consisting of a sandwich-type [ZnWMn2(H2O)2(ZnW9O34)2]12− (ZnWMn) polyanion and a hemicyanine cation of (E)-1,1′-(hexane-1,6-diyl)bis(4-(4-(dimethylamino)styryl)pyridinium) (H6), (ZnWMn/H6) n , has been deposited on quartz and indium-tin-oxide substrates through electrostatic self-assembly and studied by means of UV–vis spectroscopy, cyclic voltammetry and photoelectrochemical techniques. A uniformly deposition of the two film-forming components, evident bathochromic shift of visible absorption band of the films, compacted and ZnWMn-based quasi-reversible redox behaviours, large cathodic photocurrents of (ZnWMn/H6) n films are revealed. The effects of incorporation of ZnWMn as well as the experimental conditions including light intensities, applied bias potentials, electrolyte pH, and the film layer number on photocurrent generation of (ZnWMn/H6) n film are explored. A new hybrid electrostatically self-assembled film based on [ZnWMn2(H2O)2(ZnW9O34)2]12− (ZnWMn) polyanion and a hemicyanine cation of (E)-1,1′-(hexane-1,6-diyl)bis(4-(4-(dimethylamino)styryl)pyridinium) (H6) was uniformly deposited. The (ZnWMn/H6) n film-modified electrodes exhibited large steady cathodic photocurrent originated from excited H6*, but photocurrents generated from the (ZnWMn/H6) n film were enhanced by incorporating of ZnWMn anion.