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

A novel BiOCl/Bi5O7I (BOC-BOI) heterojunction was prepared by growing ultrathin 2D BiOCl nanosheets in situ on the surface of 3D Bi5O7I 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 Bi5O7I (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 (·O2−). Combining the results of UV-Vis DRS and Mott-Schottky test, a reasonable type II heterojunction mechanism was proposed.