Synthesis and characterization of BiOCl–Cu2ZnSnS4 heterostructure with enhanced photocatalytic activity

Cu2ZnSnS4 QDs (5–7 nm) were synthesized by chemical coprecipitation route. Using prepared Cu2ZnSnS4 QDs, a new type of BiOCl–Cu2ZnSnS4 heterostructures were prepared using bismuth nitrate as a precurssor and potassium chloride as a source of chlorine at 100 °C, 4 h. BiOCl–Cu2ZnSnS4 heterostructures were analyzed by XRD, TEM, UV–visible NIR, PL and surface area studies. The diffracted peaks of BiOCl–Cu2ZnSnS4 heterostructure show the presence of tetragonal BiOCl and did not show the intense peaks of Cu2ZnSnS4 QDs. TEM images of BiOCl–Cu2ZnSnS4 showed the deposition of Cu2ZnSnS4 QDs on the BiOCl microsphere surface. The surface area of BiOCl, Cu2ZnSnS4 and BiOCl–Cu2ZnSnS4-1 was of 1.91 m2/g, 3.06 m2/g and 13.39 m2/g, respectively. BiOCl–Cu2ZnSnS4-1 had a higher photodegradation rate for Congo red dye than BiOCl and Cu2ZnSnS4 QDs under sunlight, and that higher photoactivity was due to the heterostructure effect between BiOCl and Cu2ZnSnS4 QDs along with increased optical absorption in the visible region. Scavenger study endorses the involvement of superoxide and holes radicals in the degradation of Congo red.