3D extended polyoxoniobates/tantalates solid structure: Preparation, characterization and photocatalytic properties

Two novel 3D extended polyoxotantalates/niobates solid complexes: [Na6(H2O)13)][Li(H2O)(H3O)][(Ta6O19)] (1) and [Na6(H2O)13][Li(H2O)2][H(Nb6O19)] (2) have been assembled successfully based on double alkali metal ions (Li+ and Na+) and Lindqvist clusters ([Ta6O19]8−/[Nb6O19]8−) under aqueous solution. Both compounds have been characterized by IR, TG analysis and single-crystal X-ray diffraction. It is worth noting that Li and Na ions, different kinds of alkali ions, are first observed coexisting in two resultant solid crystal structures of polyoxotantalates/niobates. Further photocatalytic investigations show that methylene blue (MB) dye solution can be degraded by UV irradiation effectively in the presence of [Nb6O19]8−/[Ta6O19]8−. The experiments indicate that the degradation efficiency depends on pH value, irradiation time, initial MB concentration and different types of POM anions etc.