Two 2D uranyl coordination complexes showing effective photocatalytic degradation of Rhodamine B and mechanism study

Abstract

Two new hydrostable two-dimensional (2D) uranyl coordination complexes [(UO2)5(μ3-O)2(nbca)2]·7H2O (1) and [(UO2)3(nbca)2(H2O)3]·2H2O (2) (H3nbca = 5-nitro-1,2,3-benzenetricarboxylic acid) were hydrothermal synthesized. Single-crystal structural refinements reveal that both of the two complexes were formed by the packing of 2D uranyl coordination sheets via the hydrogen bonds. The nbca ligand coordinating to the uranyl polyhedron centers constructed the 2D sheets. There are UO8 hexagonal bipyramids and UO7 pentagonal bipyramids in 1 while only UO7 pentagonal bipyramids in 2. Photocatalytic degradation of rhodamine B (RhB) in aqueous solution was studied. Complex 2 possesses better performance than 1 with 96.2 % of the RhB was degraded in only 60 min. Mechanism studies reveal that the dissolved oxygens are essential to the RhB degradation. The photocurrent density of 2 is more stable than that of 1, which indicating the stronger ability to separate photoexcited electrons and hole pairs of 2.