Keggin Structure To Replace The Type Polyoxometalate Nano-structure Research

Nanostructure system is a important field, which derives from nanomaterials. Because this system has much fancy physical phenomenon and correlates with nanostructure apparatus in the future, the preparation and characterization of the nanostructure become research hotspot. In this thesis, nano- or micro-fibers of polyvinyl alcohol(PVA)/ polyoxometalates with Keggin structure substituted by different metals were prepared. By calcining the fibers, different nanostruture of pure polyoxometalates were gotten. The main results are obtained as follow:1. PVA/polyoxometalates with Keggin struture substituded by aluminium transitional metal or rare metal nano- or micro-fibres were prepared by electrospinning method. Moreover, relevant polyoxometaltes nanostructure, SiWAl nano-flakes, SiWgAla nano-tubs, SiWnMn SiW11Fe SiW11Co, SiW11Ni Ce(SiW11)2 Nd(SiW11)2nano-particles and SiW11Ti SiW11Cr SiW11Cu nano-fibres,were obtained by calcining the fibres in different temperatures.2. All products were characterized by IR spectra, X-ray powder diffraction (XRD), scanning electron microscopy (SEM). The IR spectra show that all the products still keep Keggin structure. XRD patterns show most of products having preferable crystal state. The SEM photographs show that the nanostructure shape of the products have changed.3. By investigating the different experimental phenomenon, we rationally presume and regularly summarize the process of the nanostructure as follow: (1) For the polyoxometalates substituted with transitional metal element, the change of the nanostructure shape may correlate with d or f electrons. (2) For the polyoxometalates substituted with Al, the formation process of the nanotubes is deduced, i.e. from nanofibers, nanobars, nanoflakes, to nanotubes.