NH2-mediated indium metal-organic framework as a novel visible-light-driven photocatalyst for reduction of the aqueous Cr(VI)

Metal-organic framework In-benzenedicarboxylate (MIL-68(In)) and its derivative (In-2-NH2-benzenedicarboxylate, MIL-68(In)-NH2) were prepared via a simple solvothermal method. Powder X-ray diffraction (XRD) confirmed the isoreticular nature of MIL-68(In) and MIL-68(In)-NH2, while Fourier transformed infrared spectra (FUR) proved the effective presence of amino group. Moreover, combined with UV-vis diffuse reflectance spectra (DRS) analysis, it was revealed MIL-68(In)-NH2 shown an extra absorption band in the visible light region with the absorption edge extending to around 440 nm. Importantly, MIL-68(In)-NH2 was proved to perform as an efficient visible-light-driven photocatalyst with considerable activity and stability for the reduction of Cr(VI), which could be attributed to its relatively high CB based on the result of Mott-Schottky experiment. Further experimental results revealed that the addition of hole scavenger and pH value of the reaction solution played important roles in the photocatalytic reduction of Cr(VI). Finally, a possible reaction mechanism had also been investigated in detail. (C) 2014 Elsevier B.V. All rights reserved.