Functionalized MIL-68(In) for the photocatalytic treatment of Cr(VI)-containing simulation wastewater: Electronic effects of ligand substitution

Abstract A family of functionalized MIL-68(In) have been successfully synthesized and applied to photoreduction of Cr(VI) aqueous under simulated sunlight (280 nm  2 BDC, H 2 BDC-NH 2 , H 2 BDC-NO 2 and H 2 BDC-Br) on photocatalytic performance of MIL-68(In)-X (X = H, NH 2 , NO 2 , Br). Further experimental results demonstrated that the photoactivities of the obtained MIL-68(In)-X have been greatly affected by the electronic effect of ligand substituent. That is, the reaction rates obtained by functionalized MIL-68(In) have been linearly associated with the Hammett coefficients of different substituents. More significantly, MIL-68(In)-NH 2 has also exhibited outstanding performance in a co-existed model system (Cr(VI)/dyes), which represents a first example to use the In-based MOFs as bifunctional photocatalysts. It is hope that this work not only represents the structure-property relationships on photocatalysis in MOFs, but also promotes further interest in design and construction of more efficient MOFs-based photocatalysts for environmental remediation.