Multifunctional Multilayer Films Containing Polyoxometalates and Bismuth Oxide Nanoparticles

Multifunctional multilayer films consisting of the Keggin-type polyoxometalate [SiW9V3O40](7-) (SiW9V3) and bismuth oxide nanoparticles (Bi2O3) were prepared by the layer-by-layer assembly method. For the first tithe, electrochromic and photochromic studies were done on a film containing both polyoxometalates and nanoparticles. The films were characterized by UV-vis absorption, emission spectra, and atomic force microscopy. Their electrochromic and photochromic properties were investigated by cyclic voltammetry and UV-vis spectroscopy. The results show that the reduction of SiW9V3 is very reversible and tunable with the addition of Bi2O3 layers into the film. The electrocatalytic activity of the films toward oxidation of L-cysteine hydrochloride hydrate (L-cysteine) and reduction of nitrite were studied with cyclic voltammetry. The results show that the incorporation of Bi2O3 nanoparticles into the films changed the films' photoluminescence properties and electrocatalytic efficiency.