Ultrathin BiOCl/nitrogen-doped graphene quantum dots composites with strong adsorption and effective photocatalytic activity for the degradation of antibiotic ciprofloxacin

Photocatalysis, as a green chemical technology for the removal of antibiotics, has attracted great interest recently. This study proposed a facile one-step hydrothermal process to fabricate ultrathin two dimensional (2D) BiOCl/nitrogen-doped graphene quantum dots (BiOCl/NGQDs) composites. Compared to pure BiOCl, the BiOCl/NGQDs composites exhibited enhancement in both adsorption and photodegradation for antibiotic ciprofloxacin (CIP). The optimized content of NGQDs was 6.9% and this optimized composite showed a degradation efficiency of 82.5% within 60 min under visible-light irradiation, which was considerably better than that of pure BiOCl (34.9%). Meanwhile, most of CIP was efficiently mineralized into CO2, H2O and other inorganic products, as revealed by a total organic carbon (TOC) removal efficiency of 95.5% within 5 h. The improved photocatalytic activity was attributed to excellent adsorption capability, enhanced visible-light response and efficient separation of the photoinduced electron-hole pairs in BiOCl/NGQDs composite. The active species trap experiments and electron spin resonance revealed that center dot O2- and hole mainly participated in the CIP degradation process. Such an effective strategy to design ultrathin 2D composite photocatalysts would provide a new approach for application in wastewater purification.