Integration of mixed ligand into a multivariate metal-organic framework for enhanced UV-light photocatalytic degradation of Rhodamine B

The photocatalytic activity of a series of UIO-66 modified MOFs viz. UiO-66-NO2 [1], UiO-66-NH2 [2] and UiO-66-NO2/UiO-66-NH2 [3] materials for photocatalytic degradation of model aromatic dye Rhodamine B [Rh B] have been assessed. The photocatalysis experiments indicated that the most efficient photocatalyst for the Rh B degradation is 3 which achieved 95.5% degradation under UV light irradiation and displayed excellent recyclability and reusability when compared to 1 and 2. The trapping experiments indicated that O2˙− radical anion is main ROS generated during the photocatalysis play major role in the Rh B degradation. The LC-MS experiments and band gap calculations have been performed which suggested initial protection of xanthene unit and confirmed the major contribution of O2˙− radical anion generated by ligand to ligand transition in 3 for photodegradation of Rh B. This facile approach inculcating benefits of mixed ligands in multivariate metal-organic framework, lays a new pathway to design effective photocatalytic systems for safe and sustainable degradation of aromatic dyes. This strategy led to suppression in rate of hole-electron pair recombination that concomitantly uplifted photocatalytic efficiency over single component counterparts.