Surface Na₂CO₃ etching induced activity enhancement of 2D BiOI photocatalyst working under visible light

The visible light photocatalytic activity of two-dimensional (2D) BiOI microplates was intensively enhanced through simply dipping in Na₂CO₃ solutions at room temperature. The X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) investigations suggest that little amount of (BiO)₂CO₃ phase was formed on the surface of 2D BiOI via the in situ chemical conversion. The concentration of Na₂CO₃ solutions affected the structure, morphology, light absorption and surface element component of 2D BiOI. The surface loaded (BiO)₂CO₃ mainly trapped the photoinduced electrons of BiOI, improved the separation efficiency of photocharges and finally raised the photocatalytic activity of BiOI under visible light (λ>420nm). Furthermore, the product of the as-prepared (BiO)₂CO_3/BiOI displayed excellent stability in the repeated experiment. This study provides a facile way to improve the photocatalytic activity of BiOX (X=Cl, Br, I) by means of surface treatment with Na₂CO₃ solutions.