Encapsulation of phosphotungstic acid into UiO-66-(OH)2 for synergistic and rapid photocatalytic degradation of organic pollutants

PW12@ UiO-66-(OH)2 crystal was successfully fabricated by selecting UiO-66-(OH)2 as host matrix and encapsulating phosphotungstic acid (H3PW12O40, PW12) into its cage via one-pot synthesis. Characterization with FT-IR, PXRD, EDS and XPS confirmed that both the Keggin structure of PW12 and crystal structure of UiO-66-(OH)2 maintained well in the composite. The PW12@ UiO-66-(OH)2 can act as a photocatalyst to rapidly degrade organic pollutants in aqueous solution. UiO-66-(OH)2 was not only a carrier of PW12, but also an electron donor for the photocatalytic system. Due to the synergistic effect of PW12 and UiO-66-(OH)2, the degradation rate of methyl orange (MO) with PW12@ UiO-66-(OH)2 (90.42%) was greatly enhanced compared with using PW12 (28.25%) and UiO-66-(OH)2 (39.88%). Benefiting from the perfect size matching of PW12 and UiO-66-(OH)2, PW12@ UiO-66-(OH)2 exhibited satisfactory stability and reuse effect. This work will provide a new insight into the development of MOF-based composite photocatalysts to remove organic pollutants from wastewater.