Energy level mediation of (BiO)2CO3 via Br doping for efficient molecular oxygen activation and ciprofloxacin photodegradation

Solar-driven molecular oxygen activation is of great importance for reactive oxygen species (ROS) production in environmental remediation. In this work, a convenient bromine doping strategy was developed to mediate the energy level of Bi2O2CO3 for molecular oxygen activation. The band structure and DFT calculation demonstrate that the Fermi level of Bi2O2CO3 elevates after bromine doping, which promotes the molecular oxygen activation and ROS production. The Br-doped Bi2O2CO3 exhibits remarkably enhanced photocatalytic ability and could degrade 95% of the ciprofloxacin within 30 min. Moreover, HPLC-MS analysis elucidates that the pyrrolidone ring degradation process is the dominate pathway in ciprofloxacin degradation over Br-doped Bi2O2CO3, resulting in the decrease of antimicrobial activity of the degradation products and the risk of drug-resistance. This work not only provides a molecular oxygen activation strategy via energy level mediation, but also helps us to further understand the relationship between the elemental doping and molecular oxygen activation.