The significantly boosted photodegradation of tetracycline over a novel hierarchical 0D/3D S-scheme heterojunction ZnSnO3/CdIn2S4

In recent years, constructing S-scheme heterostructure, as a novel and desirable strategy for the improvement of the photocatalytic performance, has attracted extensive interest. Herein, a novel hierarchical 0D/3D S-scheme heterostructure ZnSnO3/CdIn2S4 was constructed. The synthesized ZnSnO3/CdIn2S4 was characterized by various measures. The photodegradation of tetracycline (TC) was conducted under visible light to investigate the photocatalytic activity and stability of ZnSnO3/CdIn2S4. The impacts of pH and typical environmental factors on TC degradation were also explored. The S-scheme electron transfer mode in ZnSnO3/CdIn2S4 heterostructure was proposed based on Fermi level, in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), and identification of the active species. The ZnSnO3/CdIn2S4 heterojunction exhibits outstanding photocatalytic activity and stability. The degradation efficiency and mineralization rate of TC reach 87% and 33.5%, respectively. After five reuses of ZnSnO3/CdIn2S4, degradation efficiency of TC decreases by only 6.5%. The rate constant (0.0140 min-1) of TC degradation over ZnSnO3/CdIn2S4 is 2.41 and 43.75 times as high as those over CdIn2S4 and ZnSnO3. The dramatically boosted activity of ZnSnO3/CdIn2S4 is owing to the superior visible-light response and the significantly accelerated separation and migration of the photoproduced charge carriers due to the construction of the hierarchical S-scheme heterojunction. Moreover, the photodegradation of TC is enhanced marginally with the rising pH and is slightly inhibited by the typical ions and natural organic matters (NOM). This work brings a new strategy to design highly efficient photocatalysts applied in environmental restoration.