Room temperature synthesis of Bi4O5I2 and Bi5O7I ultrathin nanosheets with a high visible light photocatalytic performance

Bi4O5I2 and Bi5O7I ultrathin nanosheets are prepared via a facile route at room temperature. The composition, morphology, energy bands and photocatalytic properties of the materials are investigated systematically using different characterization techniques. The results reveal that Bi4O5I2 and Bi5O7I can be easily obtained by adjusting the OH- concentration at different pH values. Both Bi4O5I2 and Bi5O7I have the morphology of ultrathin nanosheets and a high surface area. With the increase of the Bi content, the adsorption edge of the samples shifts towards a shorter wavelength and the valence band edge potential becomes more positive. Thus, they exhibit a superior photocatalytic efficiency for the degradation of phenol under visible light irradiation compared to BiOI.