Boosted degradation of tetracycline over a novel hierarchical 2D/1D S-scheme heterojunction Bi2O4 @SnS under visible light irradiation

Highly efficient photocatalytic degradation of tetracyclines (TCs) has drawn increasing interest in the field of environmental remediation. Constructing S-scheme heterojunction is a desirable strategy for booting the photocatalytic activity of the semiconductors. Herein, rod-like Bi2O4 was decorated with SnS nanosheets with excellent light harvesting ability to construct 2D/1D hierarchical S-scheme heterojunction Bi2O4 @SnS. The photocatalytic degradation of TC over Bi2O4 @SnS was carried out under visible-light. S-scheme interfacial charge transfer mode was inferred via in-situ irradiated X-ray photoelectron spectroscopy (XPS). The optimum Bi2O4 @SnS composites 20-SSBO exhibits excellent photocatalytic activity and stability for degradation of TC in both deionized water and natural river water. Within 120 min, the degradation efficiency of tetracycline reaches 91%. The degradation rate constant of TC over 20-SSBO is 3.3 and 10.6 folds that over Bi2O4 and SnS, respectively. The significant enhancement of photocatalytic activity is mainly due to two aspects: On the one hand, the successful construction of S-scheme heterojunction between Bi2O4 and SnS not only effectively promotes the separation and transfer of photogenerated carriers but also preserves electrons with strong reduction ability and photogenerated holes with strong oxidation ability. On the other hand, the 2D/1D hierarchical core-shell structure resulted in increased specific surface area and broadened visible-light absorption region. In addition, environmental factor such as pH, typical inorganic cations and anions, and natural organic matters have less effect on the photocatalytic degradation of tetracycline. The possible photocatalytic degradation pathway of TC was proposed. The S-scheme heterojunction Bi2O4 @SnS have promising application in natural Environmental remediation.