Synthesis and characterization of new hybrid decatungstate anions (CTAB)4W10O32 : toward heterogeneous photocatalysis

In the present study, hybrid decatungstate based photocatalysts, [(C16H33)N(CH3)3]4[W10O32], were synthesized through the reaction of hexadecyltrimethylammonium surfactant (CTAB) and sodium decatungstate Na4W10O32.2.6 H2O (W10) using different molar ratios of W10:CTAB (1:1 for compound 1 and 1:3 for compound 2) under aqueous conditions. The characterization of these hybrid materials was carried out using FT-IR spectroscopy, UV-visible spectroscopy, TGA, XRD and SEM, which confirmed the formation of [(C16H33)N(CH3)3]4[W10O32] materials. The influences of the molar ratio on the bandgap energy, photocatalytic activity and material morphology were compared and discussed in detail. FT-IR Spectroscopy indicates that CTAB reacted with W10, producing an insoluble product in aqueous media as expected. UV-Visible spectroscopy revealed that the hybrid material with a low amount of CTAB absorbed in the visible area compared to the other one, with the optical bandgap decreasing to 2.42 eV for compound 1 in particular. The UV-visible photocatalytic degradation of carbamazepine (CBZ) in aqueous solution demonstrated the efficiency of both compounds with approximately 46 and 88% of CBZ transformation after 7 hours of exposure for compound 1 and 2, respectively. These results prove that the new hybrid decatungstate has effective photocatalytic activity, which depends on the synthesis conditions.