S-scheme 1 T phase MoSe2/AgBr heterojunction toward antibiotic degradation: Photocatalytic mechanism, degradation pathways, and intermediates toxicity evaluation

Development of efficient and stable photocatalysts is of essential for photocatalytic degradation of refractory organics in wastewaters. Herein, the novel S-scheme MoSe 2 /AgBr (MS/AB) heterojunctions were synthesized for antibiotics degradation.   Various characterization results showed that the S-scheme MS/AB photocatalysts exhibited efficient carriers’ separation and strong redox potential. Tetracycline (TC) (20 mg/L) degradation efficiency of 81.4% was achieved using the 5MS/AB within 90 min at pH of 9, superior to those of the counterparts. Photogenerated carriers' transfer and photocatalytic reaction mechanism of the S-scheme MoSe 2 /AgBr heterojunction were deduced by DFT calculation, in-situ XPS and work function calculation.   Moreover, possible degradation pathways of TC were proposed based on identified intermediates, and most of the intermediates showed lower toxicity than that of TC. The 5MS/AB photocatalyst also showed great stability and excellent antibacterial effect.   This study advances the design of efficient photocatalysts and enriches related mechanisms.