BiOI with Inherent Photo/Electric Biactivity Recovery I– by Novel Photoassisted Electrochemically Switched Ion Exchange Technology

The recovery of iodide ion (I–) from aqueous solutions is of great significance to economic development. Photoassisted electrochemically switched ion exchange (P-ESIX) takes advantage of the photo/electron bioactivity of EIXMs, which has been used for the recovery of bromide ion (Br–) to increase the adsorption capacity of Br–. To further expand the application of P-ESIX, we used iodide-vacancy bismuth oxyiodide (I–-vacancy BiOI) as the photoelectroactive ion exchange material (P-EIXM) for the recovery of I–. The results showed that an I–-vacancy BiOI film can effectively recover I– and improve the adsorption capacity because of its excellent selectivity and visible light adsorption ability. Compared with ESIX, the I– adsorption capacity increases by 1.38 times with a growth rate of 37.4% at 0.6 V (vs SCE). Also, the film electrode still retains 84.0% of the initial adsorption capacity after 10 cycles of use. The mechanism of P-ESIX system was further analyzed on the basis of the energy band structure theory. It is not only innovative and efficient technology for the recovery of I– but also shows that P-ESIX has potential as a new technology for a wide range of applications in the selective recovery of target ions.