Semiconductor photocatalysts are important for new energy exploitation and decontamination of hazardous organic pollutants because they can photoconvert solar energy into chemical energy,photodecompose organic materials,and photoreduce carbon dioxide.It is challenging to find a simple method that efficiently separates photogenerated electrons and holes.The heterolayered bismuth oxide iodate,BiOIO3,is pyroelectric.The local dipole moments of the BiO6 pyramids are practically canceled out,but those of the IO3 pyramids are not,thereby leading to a pyroelectric polarization along the c-axis direction.The superior activity was obtained over the BiOIO3 sample,on which more than 92%of MO was degraded within 12 min,as shown in Figure 1a.From Figure 1b we can see,the photo-oxidation would occur on the surface IO3 layer,and the photoreduction at one edge of the nanoplate in which the Bi2O4 layer is exposed.This enhanced photocatalytic property of BiOIO3 nanoplates is attributed to two factors; one is the heterolayered structure and the other is the internal polar field.Both features are necessary in effectively separating photogenerated electron-hole pairs at the BiO6 and IO3 pyramids.