Enhanced photodegradation of tetracycline hydrochloride by hexameric AgBr/Zn-Al MMO S-scheme heterojunction photocatalysts: Low metal leaching, degradation mechanism and intermediates

A novel hexagonal AgBr/Zn-Al MMO S-scheme photocatalyst was prepared by adopting a simplified hydrothermal and co-precipitation method. The prepared photocatalytic system exhibited excellent photocatalytic performance in degradation of tetracycline hydrochloride (TC). In particular, the ABMO0.2/Vis system generated the best TC removal rate (95%) within 60 min of visible light irradiation. Moreover, no significant decrease of the photocatalytic performance had been observed after four cycles, while the leaching of silver ions was effectively controlled. The excellent photocatalytic performance can be attributed to the synergistic effect occurring between the unique morphological structure and the S-scheme heterojunction charge transfer mechanism, since that that synergistic effect enhanced light absorption capacity and separation efficiency of the photogenerated carriers and the redox ability. In addition, liquid chromatography-mass spectrometry (LC-MS) analysis clarified the mineralization behavior and detailed decomposition pathways of TC. This work opens a new pathway for the design of efficient S-scheme heterojunctions and provides new insights into the photocatalytic degradation mechanism of antibiotics.