Layer-by-layer self-assembly polytungstogermanate multilayer films and their photocatalytic properties under sunlight irradiation

The dilacunary decatungstogermanate [γ-GeW10O36]8− (GeW10) and the monolacunary undecatungstogermanate [β2-GeW11O39]8− (GeW11) were employed as polyanions to layer-by-layer self-assembly with cationic thionine (TH) dye. The (GeW10/TH)n and (GeW11/TH)n composite films were characterized by UV–vis spectra, atomic force microscopy images (AFMs) and cyclic voltammograms (CV). Their photocatalytic activities were evaluated by photocatalytic degradation of methyl orange aqueous solution under sunlight irradiation. The results indicated that the (GeW10/TH)n and (GeW11/TH)n films exhibited the sunlight photocatalytic activities for methyl orange (MO) solution. The dye molecule TH extended the light absorption spectrum of polyoxometalates toward the visible light region. The photocatalytic mechanism of composite films was also discussed.

Graphical abstract(GeW10/TH)n and (GeW11/TH)n (TH = thionine) films exhibit the sunlight photocatalytic activities for methyl orange (MO) solution.Figure optionsDownload full-size imageDownload high-quality image (47 K)Download as PowerPoint slideHighlights► (GeW10/TH)n and (GeW11/TH)n films were prepared on solid slides through LbL self-assembly method. ► Cationic thionine (TH) dye to sensitize POMs for photocatalysis. ► GeW10/TH)n and (GeW11/TH)n films exhibited the sunlight photocatalytic activities for MO solution.