High photocatalytic activity of oxychloride CaBiO2Cl under visible light irradiation

Oxychloride CaBiO2Cl was shown as a highly active photocatalyst which can efficiently decompose methylene blue (MB), and yield high photocurrent density under ultraviolet (UV) light or visible-light irradiation. Density functional calculations revealed that the valence band (VB) was not only composed of the O 2p hybridized orbital, but also a little the Cl 3p and Bi 6p orbitals. During the calcination synthesis process, a certain amount of oxygen vacancies existed in the prepared samples, which resulted in the formation of surface hydroxyl groups. The photocatalytic activities for MB degradation were strongly dependent on the surface hydroxyl groups. By evaluation of the infrared transmission spectra (FTIR) of the series of samples, a correlation between the number of surface hydroxyl groups and the photocatalytic activity was revealed. The surface hydroxyl groups were important active sites for producing active hydroxyl radicals and a dominant factor in controlling the performance of the samples.