First-principles energy band calculation and one step synthesis of N-doped BiPO4

N-doped BiPO4 photocatalyst was synthesized by a simple one step hydrothermal method. The crystal structure, morphology, and photophysical properties of the samples were characterized by XRD, SEM, XPS, UV-Vis and Raman. The valence and conduction bands, density of states and the band gap energy of BiPO4 are calculated with first-principles. The results showed that both BiPO4 and N-doped BiPO4 have same monoclinic structure. The substitution of O2− by N3− ions in BiPO4 could not only cause the red-shift of the adsorption edge, but also change the morphology. The photocatalytic activity of BiPO4 was enhanced about 50% under UV light irradiation when the molar ratio of N/Bi is 0.2, this can be ascribed to the N3− introduced into BiPO4 crystal lattice restrain the recombination of photogenerated electron-hole pairs. However, overdoping would decrease the photocatalytic activity of BiPO4.