Engineering of 2D/3D architectures type II heterojunction with high-crystalline g-C3N4 nanosheets on yolk-shell ZnFe2O4 for enhanced photocatalytic tetracycline degradation

• 2D/3D HCCN/ZFO was prepared by a solvothermal method and a calcination process;. • 2D/3D HCCN/ZFO can enhance photo-absorption and separation efficiency of carriers;. • 2D/3D HCCN/ZFO exhibits the outstanding photocatalytic degradation activity of TC. Heterostructures constructed in various dimensions have received considerable attention as promising platforms for improving activity of photocatalytic materials. Herein, two-dimensional (2D) high crystalline g-C 3 N 4 (HCCN) nanosheets were loaded onto the surface of three-dimensional (3D) yolk-shell ZnFe 2 O 4 (ZFO) to construct 2D/3D HCCN/ZFO heterojunction by a simple two-step process consisting of a solvothermal method and a calcination process. It is found that the formation of heterojunction can effectively enhance photo-absorption and separation efficiency of carriers. In contrast to pure HCCN and ZFO, the tetracycline (TC, 30 mg/L) degradation rate of optimal 20% HCCN/ZFO heterojunction can be reached 85%, and degradation rate constant is 0.0133 min −1 , which is 3.8 and 4.9 times higher than HCCN (0.0035 min −1 ) and ZFO (0.0027 min −1 ), respectively. Besides, the reasonable mechanism of photocatalytic degradation of TC and possible intermediates products were discussed based on the results of capture experiments, electron spin resonance (ESR) and liquid chromatography-mass spectrometry (LC-MS).