Preparation of polyoxometalate nanoparticles with Keggin structure by solid-state reaction at room temperature

The polyoxometalate particles with Keggin structure, (NH4)(3)PMo12O40. 9H(2 )O(1) and (NH4)(3)PW12O40. 7H(2)O(2), were prepared firstly by solid-state reaction at room temperature. Their structure, particle sizes and appearanc es were characterized with elemental analyses, IR, XRD and TEM techniques. The size distribution of nanoparticle I is in the range of 5-14 nm, the mea n size is 9 nm, and the size distribution of nanoparticle 2 is in the range of 3-12 nm, the mean size is 6 nm, It was found that the product H2C2O4. 2 H(2)O plays a critical role in preventing the nanoparticles from aggregatin g to large particles.