Terminal-dependent ion recognition of BiOBr/PPy hybrid film with befitting absorption function for rapidly selective bromine ions removal

Abstract

The further development of promising electrically switched ion exchange (ESIX) materials with considerable selectivity and large adsorption capacity have been generally concerned in ion removal filed. Herein, a hybrid film with core–shell structure and large lattice spacing, which integrated the virtues of highly adsorptive-selective BiOBr with conductive PPy was explored to be able to synergistically remove bromine ions (Br−) from an aqueous solution by combining density functional theory (DFT) calculations with experiments. The large-area and intimate contact between BiOBr and PPy generate a built-in electric field with quasi one-dimensional charge transfer from BiOBr to PPy, inducing the activation of CC conjugated bonds with the facilitating of the structure stability and electroactivity. Interestingly, the cooperation of PPy could significantly facilitate Br− migration on account of enhancing electroactivity without affecting the adsorption capacity of BiOBr. Meanwhile, BiOBr/PPy exhibits prominent selective capacity towards Br− in the presence of other competing ions, attributing to the shielding effect of PPy, particular electron transfer between Br and Bi, sucking stability and rapid ion kinetic diffusion accelerated by befitting adsorption capacity. Furthermore, the reversible redox process demonstrates that Bi(3−x)+OBr1−x with a Bi-terminated dependent manner could store Br− in the formation of BiOBr through an ESIX procedure (Bi(3−x)+OBr1−x + xBr−↔Bi3+OBr + xe−). It is expected that this study might propel the development of electroactive materials in the ion treatment field.