Synthesis of BiOCl_xBr_1-x Nanoplate Solid Solutions as a Robust Photocatalyst with Tunable Band Structure

The use of bismuth oxyhalides as photocatalysts has received extensive interest because of their high photocatalytic activity and stability. However, available methods for the synthesis of bismuth oxyhalides with tailored morphologies, well-defined facets, and tunable band gaps are still lacking. In this work, two-dimensional BiOCl_xBr_1-x solid solution with exposed {001} facets and tunable band gaps were synthesized by using solvothermal methods. The BiOCl_xBr_1-x solid solution nanoplates crystallized in a homogeneous crystal structure but possessed continuously tuned band gaps from 3.39 to 2.78 eV by decreasing the ratio of Cl/Br. Among the synthesized nanoplates, the BiOCl_0.5Br_0.5 sample exhibited the highest photocatalytic activity for degrading Rhodamine B (RhB), a typical organic pollutant, under visible light. The highest photoactivity of the BiOCl_0.5Br_0.5 sample was attributed to a synergetic effect of higher surface area, facets exposed, and optimized band structure. The results are of profound significance for the design of novel photocatalyst materials.