Study of Sheetlike BiOI/Rodlike Bi5O7I Composite Photocatalyst by In Situ Crystallization of BiOI with pH-Dependence for Hg0 Removal

The sheetlike BiOI/rodlike Bi5O7I photocatalysts were prepared through an in situ crystallization method of BiOI with different pH values under alkaline condition. All the physicochemical properties of samples were tested by chemical characterization analysis. The results showed that the different preparation conditions of BiOI photocatalysts presented different microstructures under different pH values. When the value of pH increased from 8 to 14, the morphology of the sample gradually changed from sheetlike to rodlike. It was found that the formation of heterostructures can be constructed between sheetlike BiOI and rodlike Bi5O7I photocatalysts. Also, the photocatalytic ability of photocatalysts was tested via removing Hg0 under visible-light irradiation. All heterostructure photocatalysts exhibited outstandingly enhanced performance under the light-emitting diode (LED) lamp irradiation without any sacrificial agents in the environment. It was demonstrated that sample Bi-11.0 showed high activity in removing mercury, and the removal efficiency reached up to 63%, which improved the mercury-removal efficiency about 66.7% compared with Bi-8.0. The prominent photocatalytic performance was attributed to the internal electric field of different morphologies and the heterojunction between sheetlike BiOI and rodlike Bi5O7I, which impeded the recombination of photoelectron and hole (e––h+) pairs. This Article provides a new prospect for designing efficient photocatalysts to deal with heavy metal pollution and other environmental problems.