Ionic liquid-induced construction of 0D/3D carbon quantum dots modified PbBiO2Cl/PbBiO2Br microspheres: Boosting molecular oxygen activation for efficient antibiotics degradation

Developing highly efficient heterostructured photocatalysts for contaminants removal has long been studied, which is mainly limited by ineffective capture of visible-light photon, undesirable recombination of photoinduced hole-electron pairs, and insufficient consumption of charge carriers during surface catalytic reactions. Herein, carbon quantum dots (CQDs) modified PbBiO2Cl/PbBiO2Br nanocomposite photocatalyst have been firstly developed through in-situ ionic liquids induced synthesis. The bridge function of ionic liquids guarantees the symmetrical disperse of CQDs around PbBiO2Cl/PbBiO2Br microspheres, for synchronically overcoming the above drawbacks and markedly promoting antibiotics degradation efficiency: (i) CQDs modification harness solar photons from visible to near-infrared region; (ii) tight coupling of PbBiO2Cl and PbBiO2Br endows the heterojunction with enhanced separation efficiency of charge carriers; (iii) particular delocalized conjugated construction of CQDs strength the enrichment and utilization of photogenerated electrons. Benefiting from these distinguished features, the optimized CQDs/PbBiO2Cl/PbBiO2Br nanocomposite displays obviously enhanced photocatalytic activity towards the elimination of ciprofloxacin and tetracycline under visible light irradiation. The spin-trapping ESR spectra and radicals trapping tests demonstrate that superoxide radicals, hydroxyl radicals and holes are the major active species participated in the purification of antibiotics and the conceivable photocatalytic mechanism has been promoted. This research provides new insights into the development of CQDs modified heterostructured photocatalyst for solar energy conversion applications.