An electroactive BiOBr@PPy hybrid film with synergistic effect for electrochemically switched capture of bromine ions from aqueous solutions

The separation and capture of Br - ions from aqueous solutions is of great significance in view of their dual characteristics, that is, its economic value and its harmful effect on human body. In this study, BiOBr@PPy electroactive hybrid film with core-shell structure, which was fabricated by in-situ coating conductive PPy on BiOBr with ion storage space, was applied to selectively capture Br - ions using electronically switched ion exchange technology (ESIX). The capture capacity of BiOBr@PPy hybrid film reached 146.2 mg g −1 at 0.8 V oxidation voltage. While, the hybrid film had an excellent selectivity towards Br - ions in the aqueous solution with several competing anions. It was confirmed that selective Br - ion capture/release by the BiOBr@PPy hybrid film was achieved through the synergistic effect generated from sufficient Br - ions storage space of BiOBr, highly conductivity and ion screening function of PPy, and powerful driving forces jointly activated by the electrochemical redox reaction of BiOBr and PPy. In addition, the capacity retention efficiency and release rate of the hybrid film still remained above 80% after 10 cycles due to the strategy of in-situ coating of PPy. It is predicted that such a BiOBr@PPy hybrid film with synergistic effects may be a potential electroactive material for the separation and capture of Br - ions from aqueous solutions.