Carbon dot-bridge-constructed Z-scheme heterojunction for photocatalytic degradation of waterborne pollutants under visible light

In heterogeneous catalysis, optimizing the separation of photogenerated carriers by tuning synthesis of catalysis, is always a crucial strategy to strengthen the photocatalytic performance. Here, O vs -BiOCl@Carbon dots/Bi 2 WO 6 (OB/CB) of a Z-scheme heterojunction, was fabricated by coupling O vs -BiOCl (OB) nanosheets with carbon dots/Bi 2 WO 6 (CB) compound in one-pot hydrothermal treatment. The optimized heterojunction of OB/CB with the weight ratio of 1:2 (OB/CB-1:2) achieve the degradation efficiency of 91.66 % of Tetracycline (TCH) under the visible light, which was much higher than those of pure OB of 34.46 % and CB of 81.92 %. Meanwhile, the Z-Scheme OB/CB-1:2 also display the extremely adaptable and effective to eliminate Rhodamine B (Rh. B) of 99.43 %, Oxytetracycline (OTC) of 83.04 % and Ciprofloxacin (CIP) of 87.66 %, respectively. The photocatalytic activities are probably attributed to the recombination of photogenerated carriers, occurring at the accumulated electrons (e - ) from the conduction band (CB) of Bi 2 WO 6 (BWO) transfer to the holes (h + ) from the valence band (VB) of O vs -BiOCl in the heterojunction driven by CDs, and thus the more oxidizing h + of BWO with the more reducing e - can be retained synchronously. The extra oxygen vacancies maximize the reduction ability of e - and further support the higher photocatalytic activity of OB/CB-1:2 than other counterparts. In addition, the corresponding photoelectrochemical measurements and scavenging experiments cooperatively demonstrated that the formation of OB/CB-1:2 definitely facilitated the separation of photogenerated carriers, and further revealed that species of •O 2 ‾ and h + mainly contributed to the photodegradation. This work illustrated that the potential utilization of CDs can effectively modulate Z-scheme heterojunction to achieve water remediation etc.