Preparation And Photocatalytic Investigation Of A Self-assembly Multilayer Film Based On Keggin-type Polyoxometalate And Oxide Nanoparticles

In recent years, the use of micro-and nano-assembly of chemical engineering technology to develop new multi-functional thin films have attracted wide attention from researchers. And the oxide nanoparticles play an important role in building nano-thin film devices,which have excellent optical, electrical and catalytic properties. The polyoxometalates have attracted more and more attention because of their excellent physical and chemical properties and potential applications. In particular, polyoxometalates, due to its unique dragon-like structure and electronic diversity, having the ability to proceed in multiple, consecutive, and reversible multielectron reductions without decomposition to mixed-valence species due to their unique electronic diversity, have great significance for the electrochemistry and materials chemistry research. Therefore, the self-assembly of polyoxometalates and oxide nanoparticles can produce a new excellent photochemical and electrochemical properties, not only explore the potential application in material chemistry but also enrich polyoxometalates chemistry theory.In this paper, we mainly aim at the preparation of the composite multilayer film containing polyoxometalates and oxide nanoparticles. A series of multilayer films {PEI/[PW₁₂/TiO₂]_n} and {PEI/[PW₁₂/PEI/PSS-CdO/PEI]_n} were prepared by layer- by-layer self-assembly method. The comp- onents, structure and properties of the multilayer films were characterized by cyclic voltammetry, UV-vis, scanning electron microscope, atom force microscope, and fluorescence spectroscopy.The results showed that it was uniform and smooth from layer by layer monitored by UV-vis spectra. The images of atom force microscope indicated that the surface of the multiplayer film were smooth and dispersed with uniform spherical particles. From the fluorescence spectra of the films {PEI/[PW₁₂/ PEI/PSS-CdO/ PEI]_n}, we found that luminescent properties of nano-CdO still exists. Simultan- eously, under the UV-vis irrdiation, the UV-vis spectra of {PEI/[PW₁₂/ PEI/PSS–CdO/PEI]_n} films showed slight photochromic phenomenon at the range of the visible lignt by prolong the time of irrdiation. Photocatalytic results showed that the composite film {PEI/[PW₁₂/TiO₂]_n} and {PEI/[PW₁₂/PEI/ PSS-CdO/PEI]_n} have a higher photocatalytic activity than single component multi-layer film for methyl orange dye decolorization degradation. And proved by experiments, the composite film {PEI/[PW₁₂/PEI/PSS-CdO/PEI]_n} catalyst can be reused. The results of photo- catalytic experiments demonstrated that the multilayer films have well photo- catalytic activity with polyoxometalate and oxide nanoparticles.