Reinforced built-in electric field and mediated Schottky barrier height via carbon quantum dots electronic bridges on BiOBr/Ti₃C₂ for efficient photocatalytic quinolone antibiotics degradation

Schottky junction-based photocatalysts formed by metal-semiconductor contact are attractive, but their photocatalytic performance is limited by poor built-in electric field (IEF) driving force and excessive Schottky barrier height (SBH). A prospective strategy for efficient charge transfer is modulating interface gap states by inserting viable buffer layer. Herein, carbon quantum dots (CQDs) were inserted in BiOBr/Ti₃C₂ Schottky heterojunction to form electronic bridges via Bi–O–C and Ti–O–C chemical bonds. The CQDs electronic bridges regulated charge spatial distribution, resulting in a 3.4-fold increased IEF, and facilitated efficient charge separation and transfer within BiOBr/CQDs/Ti₃C₂. The carrier lifetime of BiOBr/CQDs/Ti₃C₂ had been extended to 2357.8 ps, increasing effectively charge carrier density. Besides, the reinforced interfacial interaction by Ti–C–O and Bi–C–O bonding significantly reduced the SBH from 2.02 eV to 1.77 eV within BiOBr/CQDs/Ti₃C₂, accelerating charge transport across the metal-semiconductor interface. Remarkably, BiOBr/CQDs/Ti₃C₂ exhibited excellent photocatalytic degradation for multiple quinolone antibiotics (FQs), especially for Moxifloxacin (MOX, 96.1 %) within 120 min, which was 2.63, 2.48 and 1.84 times higher than that of BiOBr, BiOBr/CQDs and BiOBr/Ti₃C₂, respectively. Furthermore, the high environmental adaptability and recycle stability were revealed in BiOBr/CQDs/Ti₃C₂. This work provides a new strategy to construct electronic bridges in Schottky-based photocatalysts for enhancing photocatalytic activities.