Br-doping mediated band-gap engineering contributed Bi/Bi2O2CO3 nano-platelets with enhanced photocatalytic performance

• The Br-doped Bi/Bi 2 O 2 CO 3 nano-platelets was prepared firstly. • The doping of Br narrowed the energy level of Bi 2 O 2 CO 3 significantly. • The SPR effect of Bi nanoparticles facilitated the utilization of photons. • Degradation pathways of tetracycline and toxicity of intermediates were discussed. Photocatalyst modification by energy level engineering is of great significance for the generating of active free radical. In this work, a novel strategy was employed to construct Br-doped Bi 2 O 2 CO 3 followed by in situ reduction deposited Bi nanoparticles on the surface of Bi 2 O 2 CO 3 component. Therein, the doping of Br regulated the energy level structure of Bi 2 O 2 CO 3 . The characterization of SEM and TEM intuitively displayed the morphology changes among Bi 2 O 2 CO 3 , Br-Bi 2 O 2 CO 3 and Br-Bi/Bi 2 O 2 CO 3 in size and thickness, while XRD illustrated that the decrease in shape was consistent with the increase in the half-peak width of the Br-doped samples. The Tauc spectrum verified that the bandgap of Br-Bi/Bi 2 O 2 CO 3 nanosheets was obviously narrowed, and after Bi nanoparticles were deposited on the surface of Bi 2 O 2 CO 3 by in-situ reduction of Bi 3+ with glucose, the absorption of visible light was enlarged distinctively. Excitingly, the kinetic constant of Br-Bi/Bi 2 O 2 CO 3 sample was 7.22 times higher than that of Bi 2 O 2 CO 3 , showed excellent photocatalytic performance on degrading of tetracycline. The liquid chromatography-mass spectrometry (LC-MS) was employed to deduce the possible degradation routes, and then the toxicity of tetracycline and its degradation intermediates were analysed based on quantitative structure activity relationship (QSAR).