Investigation on the Different Photocatalytic Properties of Bismuths Oxychlorides: Bi12O15Cl6 versus Bi3O4Cl versus BiOCl

It is found that under UV light (lambda <= 420 nm) irradiation, the photo activity of Bi12O15Cl6 is 1 times higher than that of BiOCl for the degradation of methyl orange (MO), which is mainly attributed to the wider light absorption range and higher charge separation efficiency, but rather than BET area (4.5m(2)g(-1)vs. 15.9m(2)g(-1)). Under visible light (lambda>420nm) irradiation, the photo activity of Bi12O15Cl6 is 3.3 times higher than that of Bi3O4Cl for the degradation of MO, which is mainly attributed to the higher charge separation efficiency and higher BET area (0.4m(2)g(-1)), rather than light absorption range (2.86 vs. 2.63eV). Under UV light irradiation (lambda <= 420nm), the photo activity of BiOCl is 1 times higher than that of Bi3O4Cl for the degradation of MO, which is mainly ascribed to the higher BET area (15.9 vs. 0.4m(2)g(-1)) and the higher charge separation efficiency, rather than light absorption (3.4 vs. 2.63eV). This work suggests that various affecting factors should be fully investigated to correctly understand the photochemical properties of a photocatalyst.