Visible-light photocatalytic activity of the metastable Bi20TiO32 synthesized by a high-temperature quenching method

Metastable Bi20TiO32 samples were synthesized by a high-temperature quenching method using α-Bi2O3 and anatase TiO2 as raw materials. The photocatalytic activity of the as-prepared samples was measured with the photodegradation of methyl orange at room temperature under visible light irradiation. The Bi20TiO32 samples exhibited good absorption in the visible light region with a band gap of about 2.38 eV and the band structure of Bi20TiO32 was studied. Photodegradation against methyl orange was much better than α-Bi2O3 prepared by the same way. The photocatalytic activity of Bi20TiO32 samples is supposed to be associated with the hybridized Bi 6s and O 2p orbitals. In addition, the dispersive characteristic of Bi 6s orbital in the hybridized valence band facilitates the mobility of the photogenerated carriers and hampers their recombination.