Facile synthesis of Bi2S3/BiOCl0.5Br0.5 microspheres with enhanced photocatalytic activity under visible light irradiation

Bi2S3/BiOCl0.5Br0.5 heterojunction composites were prepared by hydrothermally treating BiOCl0.5Br0.5 in thioacetamide (TAA) solutions with different concentrations. The compositions, morphologies, and structures of the resulting samples were studied via various characterization methods. The samples were tested in photocatalytic degradation of aqueous antibiotics and organic dyes as well as photocatalytic reduction of aqueous Cr6+. The introduction of an optimal amount of Bi2S3 to BiOCl0.5Br0.5 can expand the light absorption range effectively and lead to more photogenerated carriers. However, the presence of excess Bi2S3 on BiOCl0.5Br0.5 can inhibit the generation of center dot OH, thus leading to decreased activity in photocatalytic degradation of aqueous antibiotics and organic dyes. In contrast, the activity of the samples in photoreduction of aqueous Cr6+ increases with the increase of Bi2S3 content, because more electrons can be excited under the same irradiation. Possible photocatalytic mechanisms are discussed. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.