Synthesis of hollow TiO2@g-C3N4/Co3O4 core-shell microspheres for effective photooxidation degradation of tetracycline and MO

Abstract Traditional bulk photocatalysts often experience serious charge recombination and poor visible-light capturing, resulting in inefficient photocatalytic activity. However, proper nanostructure design usually helps to increase the activity of composite photocatalysts. Here, hollow TiO2@g-C3N4/Co3O4 core-shell microspheres are first reported. The hollow structure of the heterostructured will directionally separate the photogenerated carriers, and the photogenerated holes transferred to the surface will be further captured by Co3O4 to achieve an exposed oxidized surface. The novel multi-stage hollow microspheres can simultaneously achieve effective transfer of photogenerated carriers and extended light absorption. Benefiting from these structural and compositional characteristics, the optimized TiO2@g-C3N4/Co3O4 nanospheres have excellent photodegradation activity for tetracycline and MO. Under simulated sunlight, the degradation rates of TC (10 mg/L) and MO (25 mg/L) at 60 min are 91.6% and 97.8%, respectively. At the same time, high activity is maintained after multiple cycles of testing. Possible transfer paths for photogenerated carriers have also been proposed. This work will provide more inspiration for the design of multi-stage hollow photocatalytic systems.