Low melting point and high stability polyoxomolybdate-based ionic liquids as photocatalysts

The polyoxometalate-imidazole ionic liquids(POM-ILs) with low melting points at 94.5 and 95.5 °C, [C_nmim]₄[Mo₈O₂₆](C_nmim=1-alkyl-3-methylimidazolium, n=12,14), have been successfully synthesized and characterized by DSC, single-crystal X-ray diffraction and TGA, etc. The two POM-ILs have relatively high stability with decomposing temperature up to about 347 and 344 °C, respectively. Further photocatalytic performance was measured via the degradation of rhodamine B(RB) in aqueous solution. The experiments show that the conversion reached to 90% after 90 min under UV-light and the degradation efficiency depended on pH value, different dosages and so on. In addition, the catalysts can be recycled for several times without significant loss of activity.