Highly Improved Photocatalytic Activity of Magnetically Separable Ferroferric Oxide@Zinc Oxide/Carbon Nitride Nanocomposites and Interface Mechanism

Magnetic Fe3O4@ZnO/g-C3N4 nanocomposites were synthesized with two-step method. Fe3O4@ZnO anchors on the surface of g-C3N4 to form Fe3O4@ZnO/g-C3N4 nanocomposites. Fe3O4@ZnO/g-C3N4 nanocomposites greatly improve the photocatalytic activity to MB. The heterojunction interface efficiently separated the photogenerated electrons and holes. All samples could be easily separated with magnetic separation method. To develop an efficient and recyclable photocatalyst, ternary magnetic Fe3O4@ZnO/g-C3N4 nanocomposites were synthesized for the photodegradation of methylene blue (MB). The microstructures, magnetic response and photocatalytic activity of the as-prepared nanocomposites were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), N-2 adsorption-desorption isotherms and spectrophotometer. All results indicate that ZnO nanoparticles anchor on the surface of Fe3O4 nanoparticles and Fe3O4@ZnO exists on the surface of g-C3N4 to form Fe3O4@ZnO/g-C3N4 nanocomposites. The photocatalytic activity to MB of Fe3O4@ZnO/g-C3N4 nanocomposites is significantly higher than those of pristine g-C3N4 and Fe3O4@ZnO. Owing to the heterojunctions between the interface of g-C3N4 and ZnO, the high separation efficiency of the photogenerated electrons and holes increases the radicals center dot OH and center dot O-2(-) to photodegrade MB. Fe3O4@ZnO/g-C3N4 (20%) presents the highest MB removal of 93.74% and could be easily separated from solution with magnetic separation method.

Automated summary

Ternary magnetic Fe3O4@ZnO/g-C3N4 nanocomposites were synthesized for the photodegradation of methylene blue, showing significantly higher photocatalytic activity than pristine g-C3N4 and Fe3O4@ZnO. The efficient separation of photogenerated electrons and holes at the heterojunction interface led to increased radicals production for MB degradation. Fe3O4@ZnO/g-C3N4 (20%) exhibited the highest MB removal of 93.74% and could be easily separated from solution using magnetic separation.