Unravelling the critical role of biomass carbon dots in atomic co-sharing Sb2S3/Sb2WO6 heterojunctions: Boosting photocatalytic water purification via precise dual-electric field

Developing an efficient, recyclable, and sustainable photocatalyst is crucial for the removal of both inorganic and organic pollutants in water matrices. In this study, N-doped biomass carbon dots (NCDs) sensitized Sb₂S₃/Sb₂WO₆ (NCSSWO) heterostructures were constructed for simultaneously photocatalytic removals of Cr(Ⅵ) and ofloxacin under 10 W LED irradiation using an in-situ microwave-assisted ion exchange method. The optimal NCSSWO-1 exhibited superior performance for both Cr(Ⅵ) and ofloxacin elimination, yielding up to 24.1 and 1.9 times greater Cr(Ⅵ) and ofloxacin rate constants, respectively, than pristine Sb₂WO₆. Notably, the ability of NCSSWO-1 to remove Cr(Ⅵ) and ofloxacin in co-existing systems is evidently better than in single-pollutant systems. Experimental and theoretical analyses reveal the prominent activity is attributed to multiple roles caused by the formation of an intense dual-electric field. Specifically, the Sb–S/Sb–O bonds at Sb₂S₃–Sb₂WO₆ heterointerface endow atomic co-sharing electron channel for accelerating charge separation. Moreover, the NCDs are imperative for the charge-oriented accumulation near the Sb₂WO₆ side via van der Waals interactions and provide extra light-harvesting and reactive centers. Additionally, the ofloxacin decomposition process, intermediate biotoxicity, and catalytic mechanism were confirmed. This synergistic eradication strategy of constructing dual Z-scheme heterostructure via interfacial engineering offers valuable insight into developing ternary-based photocatalysts for efficient environment purification.