Construction of microspherical flower-like Zn3In2S6-BGQDs/AgBr S-scheme heterojunction for photocatalytic elimination of nitrofurazone and Cr (VI)

It is crucial to design efficient photocatalysts for elimination of combined pollutants in wastewater. Herein, the S-scheme Zn 3 In 2 S 6 -BGQDs/AgBr (ZBA) heterojunction was synthesized through co-modification of Zn 3 In 2 S 6 with B-doped graphene quantum dots (BGQDs) and AgBr nanoparticles using solvothermal method for synchronous removals of nitrofurazone (NFZ) and Cr (VI). Characterization results revealed that ZBA showed superior photocatalytic activity than the counterparts. In NFZ-Cr (VI) coexistence environment, removal efficiencies towards NFZ and Cr (VI) were 95.23% and 99.39% using the ZBA photocatalyst within 2 h of visible light irradiation. Results demonstrated that ∙OH, h + and ∙O 2 − played major role for NFZ removal, while mainly e - and ∙O 2 − contributed to Cr (VI) reduction. The S-scheme heterojunction mechanism of ZBA was confirmed by energy band structure analysis, ESR and calculated work function.   Possible pathways and mechanisms of NFZ degradation were proposed according the identified intermediates. Besides, the ecotoxicity of intermediates was analyzed. This study advances the development of photocatalytic treatment of combined-polluted wastewater.