A stable Zn-MOF with anthracene-based linker for Cr(VI) photocatalytic reduction under sunlight irradiation

Abstract

The highly desired goal is to employ visible light for the photocatalytic reduction of toxic Cr(VI) to environmentally friendly Cr(III). Metal-organic frameworks (MOFs) are considered one of the most promising materials for the photoreduction of Cr(VI). Nevertheless, developing MOFs with high stability and activity is still challenging. Herein, we report a stable Zn-based MOF (named DZU-64 ) with an anthracene functionalized ligand, and its reduction of Cr(VI) under sunlight irradiation was investigated. DZU-64 exhibits excellent chemical stability in pH range of 2−14 aqueous solution, and remarkable thermal stability to 570 °C. For the photoreduction of Cr(VI) under visible light irradiation, DZU-64 gives a record rate constant of 0.467 min −1 and a high Cr(VI) reduction rate of 6.68 mg Cr (VI) g −1 cata min −1 at pH 2. Moreover, under real solar light, DZU-64 can also efficiently reduce Cr(VI) to Cr(III) while retaining its catalytic activity throughout 5 cycles without any notable decline, further demonstrating its great application prospect. By combining the photovoltaic performance tests and electron spin resonance test, the possible photoreduction of Cr(VI) mechanism in DZU-64 was analyzed. A new photoactive Zn(II) metal-organic frameworks was designed through a rational strategy of implantation using a photosensitive anthracene linker. Benefitting from its robust framework and suitable porous environment, it exhibited significant removal efficiency for Cr(VI) wastewater under both simulated and real sunlight irradiation.