The Morphology Effect on Ca-Bi-O System Photocatalytic Property under Visible-light Irradiation

摘要

Four main phases in Ca-Bi-O systems, Ca_6Bi_6O_(15), Ca_4Bi_6O_(13), CaBi_2O_4 and Ca_5Bi_(14)O_(26) were prepared by solid-state reaction method. UV-visible absorption spectra show that the samples of CaBi_2O_4, Ca_4Bi_6O_(13) and Ca_5Bi_(14)O_(26) have visible-light reactivity with the band gap of 3.08 eV, 2.76 eV and 2.60eV, respectively. The results of SEM and BET measurements indicate that CaBi_2O_4 has the morphology of flower-like nanostructure and the high BET surface area, while Ca_6Bi_6O_(15), Ca_4Bi_6O_(13), and Ca_5Bi_(14)O_(26) have the morphology of particles of various shapes with a diameter from 200 nm to 2 μm and low BET surface area. CaBi_2O_4 was found to be a most efficient visible-light-driven photocatalyst in degradation MB. This work may deepen the understanding of the relationship between the photocatalytic properties and the crystal structures in Ca-Bi-O system.