Low Fe-doped Bi2O3 photocatalyst with long wavelength response: Crystalline transition and mechanisms by first-principles calculation

The low Fe-doped Bi2O3 with different crystalline phases was synthesized by a solvothermal method. With the increase of annealing temperature, the crystalline phase of the low Fe-doped Bi2O3 was transformed from Bi2O2CO3 to monoclinic α-Bi2O3 and cubic Bi25FeO40. Among them, the mixture of α-Bi2O3 and Bi25FeO40 (annealed at 600 °C) showed the highest photocatalytic activity for decomposing pentachlorophenol (PCP) under visible light irradiation (99.2% removal rate). Both theoretical calculations and experimental results support that Fe-doping brings about the hybridization of the energy levels and the modification of electron structure, which is responsible for extending the photoabsorptivity to the visible light region (<623 nm) and strengthening the photocatalytic activity of Fe-doped Bi2O3.

► Low Fe doping induces crystalline transition of Bi2O3.
► The mixture of α-Bi2O3 and Bi25FeO40 by Fe doping shows the highest activity.
► Fe 3d energy level extends the Bi 6p conduction band.
► The optical absorption of Fe-doped Bi2O3 is expended to less than 623 nm.
► Pentachlorophenol was removed by Fe–Bi2O3 under visible light rapidly.