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

Abstract: 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. Graphical Abstract: [Figure not available: see fulltext.]