The characteristics and photocatalytic activities of BiOCl as highly efficient photocatalyst

► BiOCl shows high photoactivity because of the electrons trapped by O 2 vacancies. ► The high activity closely related with the internal electric field between [Bi 2O 2] and [Cl 2] slabs. ► The correlation between the activity and crystal structure was discussed. ► The photocatalytic mechanism of BiOCl was tentatively discussed. BiOCl was synthesized by hydrolysis method. In order to evaluate their photocatalytic activity, this compound was tested on the degradation reaction of methylene green in aqueous solution. The characterization of the compound included: X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopic image (TEM). MG could be efficiently degraded in aqueous suspension of BiOCl under visible light irradiation. Complete removal of aqueous methylene green (MG) was realized after visible light irradiation for 120 min with existing BiOCl as a catalyst. The decrease of the chemical oxygen demand (COD), the formation of inorganic products ( SO 4 2 - and NO 3 - ) confirmed complete mineralization of aqueous MG during the photocatalytic process.