Bingbing Xu

Enhanced electrochromic performance of composite films by combination of polyoxometalate with poly(3,4-ethylenedioxythiophene)

A composite film containing poly(3,4-ethylenedioxythiophene) (PEDOT), polyoxometalate (POM) clusters K6P2W18O62·14H2O (P2W18) and polyallylamine hydrochloride (PAH) was fabricated by a smart combination of layer-by-layer (LbL) with electro-polymerization methods. The composite film displays enhanced electrochromic performance by incorporation of P2W18 into the PEDOT film. The electrochromic property of the film is significantly improved, resulting in an optical contrast of 54.7% at 600 nm and an absorbance that does not change after 1500 cycles. Additionally, the film provides broader absorption throughout the visible region. These results demonstrate the essential role of POMs in improving functionality on PEDOT for applications in electrochromic devices.

Enhanced photovoltaic response of the first polyoxometalate-modified zinc oxide photoanode for solar cell application

A photovoltaic electrode consisting of polyoxometalate (SiW12) and zinc oxide (ZnO) was fabricated on indium tin oxide (ITO) glass by one-step electrodeposition. The addition of SiW12 strongly influences the morphology and crystallographic orientation of the ZnO. The photovoltaic properties of the ZnO film and the SiW12–ZnO composite films were investigated via solar cell assembly. Both transient photocurrent and current–voltage curve measurements demonstrate that the photocurrent and power conversion efficiency of the SiW12–ZnO composite film were markedly enhanced in comparison with that of the ZnO film. Based on the results of fluorescence quenching measurements, the enhanced photovoltaic effect should be attributed to the occurrence of the photoinduced electron transfer between polyoxometalate and ZnO, which increases the efficient dissociation of excited electron–hole pairs (excitons).

Effects of film structure on electrochromic properties of the multilayer films containing polyoxometalates

Multilayer films of tungstophosphate anion (P(2)W(18)) and poly(allylamine hydrochloride) (PAH) were fabricated on quartz and ITO substrates by layer-by-layer self-assembly method. These films were characterized by UV-vis spectroscopy, cyclic voltammetry (CV), chronoamperometric (CA), chronocoulometry (CC) and atomic force microscopy (AFM). The effects of film structure on multilayer electrochromic properties were investigated. The electrochromic responses of the composite films were related to the surface coverage of anion and multilayer thickness. It was found that higher concentration of polycation and anion, or adding salt to the polycation solution used for multilayer film preparation led to thicker and denser film structure which improved optical contrast and coloration efficiency whereas prolonged response time.

Polyoxometalate-based gasochromic silica

Materials capable of gasochromic behavior are still rare. In this paper, amorphous gasochromic hybrid silica material containing phosphomolybdic acid (PMo12) is prepared by the sol–gel technique. The structure and properties of the material are investigated by cyclic voltammetry, thermal gravimetric analysis, FT-IR spectra, X-ray diffraction, UV-Vis spectra and X-ray photoelectron spectra. The structural integrity of phosphomolybdic acid has been preserved after incorporation into the porous silica framework. Furthermore, the PMo12–SiO2 hybrid material shows sensing activity for H2S and SO2 gases at room temperature based on the color change.

Fabrication of polyoxometalate-based nano/micrometer composite films by electrophoretic deposition method.

Keggin-type heteropolyanion H(3)PMo(12)O(40) encapsulated by a cationic surfactant dioctadecyldimethylammonium chloride (DODACl) has been assembled on ITO substrates using an electrophoretic approach. The films were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), IR spectra, X-ray photoelectron spectra (XPS) and cyclic voltammetry. The AFM images exhibit a spherical assembly of surfactant-encapsulated complex (SEC) nanoparticles with uniform size. The SEM was also used to investigate the surface topography. It is the first report that the thin films of SEC are fabricated using this method, which provides a new route to explore the possibility of application to polyoxometalate-based hybrid inorganic-organic materials.