Bi-template effect of a vegetal system on the synthesis of alkaline-earth tungstate nanocrystals

The MBS (mung bean sprouts) vegetal system, with its high penetrability, high selectivity, and space restriction, was explored to control nanocrystal synthesis. We found that the inside and outside of MBS have different structures and ion transformation properties. Two nanocrystals with distinct morphology, the nanorod and the nanosphere, were grown on the Outer surface and the inner stem wall of MBS, respectively. The two XWO4 (X = Ca, Sr, Ba) nanocrystals were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared (FTIR). The FTIR spectra of nanoproducts were different from bulk products due to the nano-size effect. A presumable mechanism was also determined. This work benefits the application of nanotungstates.