Figure 3: Bandgap states of Bi2WO6 samples.

(a) Diffuse reflectance ultraviolet–visible spectra of Bi2WO6 samples. (b) Calculated density of states (DOSs) of Bi2WO6 bulk, pristine monolayer and Br-modified monolayer. The Fermi level is taken as the energy zero. (c) Band energy diagrams of Bi2WO6 nanocrystals and monolayers. W, O, Bi and Br atoms are represented as blue, red, purple and yarrow spheres, respectively.