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

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−1cata 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.