Multi-anions-coupled electronic states in Cl−-doped BiOBr induce highly efficient decomposition of tetracycline hydrochloride

A series of flower-like BiOCl x Br 1-x (x = 0∼1) with different Cl − doping contents were prepared via a simple co-precipitation method. Experimental results show that BiOCl 0.2 Br 0.8 (20 mg) can decompose tetracycline hydrochloride (20 mg/L) of ∼100% within 30 min, which is far higher than those of the previously reported BiOCl and BiOBr. Microstructural and spectroscopic characterization demonstrates that Cl − doping can effectively change the growth orientation of the layered BiOCl x Br 1-x nanosheets to expose more (102) active surfaces. Density of states calculations and radical trapping experiments reveal that strong coupling between the electronic states of multi-anions adjusts the band structure, which improves light absorption and generation of main active species ⋅O 2 − . Meanwhile, strong polarization caused by anionic doping also promotes separation and migration of the photogenerated carriers to different positions of the active surface. As a result, the photocatalytic activities are improved largely and optimal in BiOCl 0.2 Br 0.8 .