In-situ fabrication of novel BiOCl/Bi5O7I 2D/3D heterostructures with enhanced photocatalytic activity

A novel BiOCl/Bi 5 O 7 I (BOC-BOI) heterojunction was prepared by growing ultrathin 2D BiOCl nanosheets in situ on the surface of 3D Bi 5 O 7 I microspheres . The 2D/3D heterostructure of BOC-BOI composites inhibited the agglomeration of BiOCl nanosheets, and benefited the multiple reflection and refraction of light, which greatly enhanced the absorption and utilization of light. The 50-BOC-BOI composite showed 97.7% degradation efficiency of rhodamine B (RhB) after 70 min Xe light irradiation. And its apparent degradation rate constant ( k ) was 0.0377 min −1 , being 4.9 and 15.1 times than that of pristine BiOCl (0.0077 min −1 ) and Bi 5 O 7 I (0.0025 min −1 ), respectively. The enhanced photocatalytic activity of BOC-BOI composites was attributed to stronger light capture ability, more abundant active sites and higher charge carrier separation efficiency, confirmed by UV-Vis DRS, SEM, TEM, BET, Zeta potential and electrochemical characterizations. The free radical capture experiments showed that the main active species in this system were holes (h + ) and superoxide free radicals (·O 2 − ). Combining the results of UV-Vis DRS and Mott-Schottky test, a reasonable type II heterojunction mechanism was proposed.