Ionic liquid-assisted synthesis of defect-rich BiOI with controllable structure and high surface area for excellent visible-light photocatalytic activity

In this study, BiOI materials with controllable structure are designed by using ionic liquid as I source and template to create the surface oxygen defects, thus promoting the photogenerated carrier migration and enhancing the photocatalytic activity. The texture of BiOI is controlled by adjusting the pH values of reaction mixture and the corresponding formation mechanism is also explored based on the self-assembly behavior of ionic liquid. It is found that the sample BiOI-7 possesses the ultrathin nanosheets (2 ~ 4 nm) and abundant surface oxygen defects which are beneficial for accelerating carrier transfer and facilitating photocatalytic degradation. The photocatalytic activity of as-prepared BiOI is studied by using Rhodamine B (RhB), methyl orange (MO) and Bisphenol A (BPA) as target pollutants, respectively. Besides, water splitting reactions were also used to further check the photocatalytic activity. BiOI samples exhibit the enhanced photocatalytic activity than bulk BiOI and g-C 3 N 4 obtained by calcination of melamine. Especially, 92% of bisphenol A (BPA) can be degraded under light irradiation within 1 hr by using only 5 mg of BiOI-7 nanosheets, which is superior than most counterparts reported so far. This rapidly synthetic route can be applied in fabrication of other novel materials with diverse morphology and porous structure.