No abstract

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.

A Bi-based oxychloride Bi(3)O(4)Cl with a layered structure as a novel efficient photocatalyst was studied in the present paper. The compound synthesized by a solid-state reaction method has a band gap of 2.79 eV. The material possesses a fair visible-light-induced photocatalytic activity. Generally, the photocatalytic efficiency of Bi(3)O(4)Cl for degrading methyl orange (MO) is higher than that of anatase TiO(2) under UV light illumination. The dispersion of Ag over Bi(3)O(4)Cl leads to an obvious increase in the photocatalytic performance. The MO decolorization over Bi(3)O(4)Cl is mainly initiated by a photocatalytic process. The photocatalytic activity is discussed in close connection with the crystal structure and the electronic structure in details.