Self-assembly of polyoxometalate–azure A multilayer films and their photocatalytic properties for degradation of methyl orange under visible light irradiation

Multilayer films (PW12–AA)n (PW12 = PW12O403-, AA = azure A, n is the number of PW12–AA bilayers) were prepared on solid slides via a layer-by-layer (LbL) self-assembly method. The growth of the films was characterized by UV–vis spectra, FTIR spectra, and atomic force microscopy (AFM). The results show that the deposition process is linear and reproducible from layer to layer and the PW12 is intact during the self-assembly process. AFM images indicate that the film surface is smooth and uniform. Moreover, the photocatalytic property of the films was investigated by the decomposition of methyl orange (MO) under visible light irradiation (λ > 420 nm). The multilayer films show photocatalytic activity for the degradation of MO under visible light irradiation using a xenon lamp and sunlight. The kinetics of the photodecomposition follows the first-order reaction.

AA is excited by visible light to appropriate excited states. Then, the electrons inject into the conduction band of POMs to form O2-, decomposing the MO molecules.Figure optionsDownload high-quality image (44 K)Download as PowerPoint slideResearch highlights
► (PW12–AA)n multilayer films can be prepared via layer-by-layer self-assembly method.
► (PW12–AA)n films show photocatalytic activity to decompose MO molecules.
► AA has played a role as a sensitizer to extend the UV adsorption of PW12 to the visible region.