Photocatalytic Activities of Heterojunction Semiconductors Bi2O3/BaTiO3:  A Strategy for the Design of Efficient Combined Photocatalysts

The heterojunction semiconductors Bi 2 O 3 /BaTiO 3 were prepared by a milling-annealing method. The powders were characterized by X-ray diffraction (XRD), the Brunauer−Emmett−Teller (BET) method, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and UV−vis diffuse reflection spectroscopy (DRS). Their UV-induced photocatalytic activities were evaluated by the degradations of methyl orange and methylene blue. The results generally show that the heterojunction semiconductors Bi 2 O 3 /BaTiO 3 exhibit better photocatalytic properties than the single-phase BaTiO 3 or Bi 2 O 3 . The obviously increased performance of Bi 2 O 3 /BaTiO 3 is ascribed mainly to the electric-field-driven electron−hole separations both at the interface and in the semiconductors. A strategy for the design of efficient heterojunction photocatalysts was proposed. That is, an electron-accepting semiconductor and a hole-accepting semiconductor with matching band potentials, which respectively possess high electron and hole conduction abilities, are tightly chemically bonded to construct the efficient heterojunction structure.