Partial disorder structured BiOI atomic layers boosting excitons dissociation for photocatalytic CO2 reduction and pollutant removal

Owing to atomic-thin thickness, reduced dielectric screening will usually happen in 2D atomic layers and lead to the formation of strong exciton effect, which is not energetically for some photocatalytic reactions. In this work, a scalable fast synthesis strategy is developed to fabricate BiOI atomic layers with partial disorder area (BiOI-D) at room temperature, as observed by HAADF-STEM image. This order–disorder interface in BiOI atomic layers favors boosting excitons dissociation to free charge carriers. Due to the atomic-thin thickness for rapid bulk charge diffusion and order–disorder interface for excitons dissociation, this BiOI-D atomic layers display greatly improved charge separation efficiency compared to BiOI nanosheets, thus contribute to enhanced photocatalytic activity for pollutants degradation and CO2 reduction. Compared to BiOI nanosheets, a 12.5 times increased CO2 photoreduction activity can be realized over BiOI-D atomic layers, with the CO generation rate of 15.1 μmol g−1 in 5 h. Profiting from the order–disorder interface, CO2 activation energy barrier can be lowered and rate-limiting step energy barrier for COOH* formation is decreased from 0.67 to 0.34 eV.