Novel n-p-n heterojunction of AgI/BiOI/UiO-66 composites with boosting visible light photocatalytic activities

Antibiotics, considered as persistent organic pollutants, have harmful effect on the environment and human health. We aimed at designing and fabricating ternary AgI/BiOI/UiO-66 composites and evaluate the photocatalytic activities of tetracycline (TC) in water environment under visible light irradiation. X-ray diffractometer (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and ultraviolet-visible (UV-vis) diffuse reflectance spectra (DRS) analyses were carried out to characterize the ternary AgI/BiOI/UiO-66 composites. The effects of pristine BiOI, UiO-66, and AgI loading ratios on the AgI/BiOI/UiO-66 composites for TC photodegradation were evaluated to obtain the optimal one (1-ABU), which can remove 90.1% TC with visible light irradiation. In the batch experiment, the influences of pH, ion strength, TC concentration, and dosage of photocatalyst were investigated. 1-ABU exhibited excellent photocatalytic activities and stability including pH and ion strength resistance in certain degree. After recycled five times, 1-ABU still showed good degradation efficiency, indicating the advanced stability of the ternary composites. center dot OH and h(+) active species are the prime, whereas center dot O-2(-) act as secondary during the TC degradation process. 1-ABU exhibits an n-p-n heterojunction, which can inhibit the recombination of photogenerated electron-hole pairs and generate more active center dot OH species. This work highlights a reference for the design and synthesis of heterojunction for excellent photocatalytic performance.