In-situ growth of ZnO globular on g-C3N4 to fabrication binary heterojunctions and their photocatalytic degradation activity on tetracyclines

The zinc oxide/graphitic carbon nitride (ZnO/g-C 3 N 4 ) heterostructured nanocomposite was successfully synthesized by a facile two-step process involving thermal condensation of melamine and hydrothermal in situ growth of globular zinc oxide (ZnO) nanoparticles on the surface of graphitic carbon nitride (g-C 3 N 4 ). The morphologies, chemical compositions, and optical properties of the prepared ZnO/g-C 3 N 4 were investigated via a series of characterization techniques. SEM and TEM validate the grafting of ZnO globular with a diameter of 40–50 nm on the surface of g-C 3 N 4 . The visible photodegradation activity of the nanocomposite was assessed via tetracycline and oxytetracycline as target pollutants. Under visible light irradiation, 15 wt% ZnO globular-g-C 3 N 4 exhibits high photocatalytic activity with 78.4% of tetracycline degraded in 50 min and 63.5% of oxytetracycline in 50 min which was much faster photocatalytic degradation efficiency than that of the reported materials. Reactive species scavenging experiments revealed that photogenerated holes are the main reason for the photocatalytic degradation. After six recycles, the ZnO globular-g-C 3 N 4 resulted in 70% degradation efficiency of TC suggesting its high stability and reusability. This work proved a new insight for constructing novel high-performance photocatalysts for TC degradation.