Photoelectric active hybrid film based on RuII terpyridyl complex and EuIII substituted Keggin polyoxometalate of [Eu(BW11O39)2]15−

The hybrid film consisting of alternating layers of EuIII substituted Keggin polyoxometalate anion [Eu(BW11O39)2]15− (EuBW) and RuII complex cation of [Ru(L)2]2+ {L = 4′-(4-(imidazol-1-yl)phenyl)-2,2′:6′,2″-terpyridine}, abbreviated as RuL1, was prepared on quartz and indium-tin oxide (ITO)-coated glass substrates by electrostatically self-assembled method, and studied by UV-vis absorption spectroscopy, cyclic voltammetry, permeability of the film to the redox probe [Fe(CN)6]3−, electrochemical impedance spectroscopy and photoelectrochemical measurements. The uniform depositions of the two components into the films were evidenced by uniform growths of the UV-vis absorption peaks. The ITO electrodes modified with the hybrid film showed stable electrochemical property in relation to EuBW anion and RuL1. The significant cathodic photocurrent generation was observed upon visible light irradiation with a maximum photocurrent density of 8.47 μA/cm2 being achieved for a 5-layer film of (EuBW/RuL1)5 at an applied potential of −0.3 V versus saturated calomel electrode. The effects of substitution atoms in MBW (M = EuIII vs. ZnII) and experimental conditions including applied bias potentials, layer numbers of the films and irradiated light intensities on photocurrent generation were discussed.