Dual roles of basic bismuth nitrates in the composites: morphology regulation and heterojunction effects

Generally, the construction of heterojunctions is considered as a simple and efficient method to enlarge visible light response of broad band gap semiconductors and improve separation efficiency of charge carriers of single component. Given that basic bismuth nitrate [Bi6O5(OH)(3)](NO3)(5)center dot 3H(2)O (labeled as BBN-5N) could not be irradiated by visible light, herein, the heterojunction BiOBr/BBN-5N has been prepared by using a facile co-precipitation method at room temperature, which exhibited enhanced photocatalytic activity for the degradation of malachite green and tetracycline under visible light illumination as compared to pure BiOBr and BBN. The structure and property characterization indicate that BBN in the composites could not only restrict the recombination of the photogenerated carriers but also benefit for the formation of highly dispersed flower-like BiOBr. By removing BBN in the composites, the remaining flower-like BiOBr exhibited better photocatalytic activity than sheet-like BiOBr obtained by adding excessive KBr into Bi(NO3)(3)solution. Similar phenomena could be observed for the composite [Bi6O6(OH)(2)](NO3)(4)center dot 2H(2)O/BiOBr (labeled as BiOBr/BBN-4N). This work sheds light on the preparation of the heterojunction photocatalysts with controlled morphology.