Enhanced electroactivity of BiOCl/PPy hybrid film with anamnestic lattice site for synergistically efficient selective uptake/release of chloride ions. (1st August 2022) - Zhang, Wei
Highlights: Synergistic effect of PPy and BiOCl accelerates the uptake/release of Cl − ions. Ion recognition with ultra-affinity is realized by memory effect of lattice sites. Induced built-in electric field provides driving force for ion transportation. Cl − as an information conveyor relating to BiOCl and PPy enhances electroactivity. Abstract: In this work, density functional theory (DFT) calculation was applied for the electronic property analysis to illustrate the internal mechanism of electroactive ion exchange hybrid film BiOCl/PPy during the experiment for the uptake/release of chloride ion (Cl − ) in the interface of BiOCl and PPy. Adsorption and diffusion barrier calculations demonstrated that both selectivity and surface diffusion of Cl − for BiOCl/PPy hybrid film were superior to those of isolated BiOCl and PPy, which were attributed to the memory effect of unique lattice sites on BiOCl and the screening effect of PPy. Combining DFT calculation with XPS analysis, it is found that Cl − could be synergistically confined in the fourfold hollow lattice sites (H) and the top sites (T) acting as ion diffusion channels, thereby generating excellent selectivity recognition ability towards Cl − even in the coexisting of other ions. Furthermore, it is revealed that BiOCl/PPy hybrid film can consistently maintain metallicity during the Cl − up-taking process, which should originate from the built-in electric fields owing to the information delivery of Cl − since it could effectively activate BiOCl and actuate ion migration with a satisfactory uptake/release rate. Moreover, the effective masses of electrons for H-site ions (me */mо = 0.38) and T-site ions (me */mо = 0.47) were used to effectively predict how the dangling electrons can reach a saturation at T-sites and to attest how Cl − can be desorbed from T sites and adsorbed from H sites. As a result, the electroactive BiOCl/PPy hybrid film showed excellent performance in the extraction of Cl − . Graphical abstract: Image, graphical abstract