Enhanced Photocatalytic Performance of Hierarchical ZnFe2O4/g-C3N4 Heterojunction Composite Microspheres

Semiconductor photocatalysts with suitable band gap for fair response to visible light and efficient separation of electron–hole pairs, are the key to practical application of photocatalytic technology. Magnetically separable hierarchical ZnFe2O4/g-C3N4 composite photocatalysts were prepared by a facile solvothermal method combined with a subsequent annealing process. The composite microspheres were composed of ZnFe2O4 nanoparticles, whose diameter was restricted due to the confined space effect from g-C3N4 nanosheets. ZnFe2O4/g-C3N4 heterojunction structures led to the improvement of the efficiency for photodegrading methylene blue and rhodamine B under visible light, where the kinetic constant over ZnFe2O4/CN-150 photocatalyst was more than ten times larger than that over pure ZnFe2O4. The photogenerated electrons from g-C3N4 surfaces could easily migrate to ZnFe2O4, leading to efficient separation of electron–hole pairs. Also, the composite photocatalyst possessed a chemical stability against photocorrosion and a magnetic property, which made it magnetically separable and reusable conveniently.