Fabrication uniform hollow Bi₂S₃ nanospheres via Kirkendall effect for photocatalytic reduction of Cr(VI) in electroplating industry wastewater

Hazardous hexavalent chromium removal from wastewater is an urgent issue in industry environmental pollution. In this work, hollow Bi₂S₃ nanospheres have been successfully synthesized from unique Bi₂O₃ porous nanospheres via Kirkendall effect through hydrothermal process. It was found that the sulfur source and the initial Bi₂O₃ templates played key roles in the formation of the uniform morphologies and structures through an anion exchange process. Compared with other Bi₂S₃ samples, the synthesized hollow Bi₂S₃ nanospheres exhibited much enhanced photocatalytic ability for Cr(VI) photoreduction. XPS analysis demonstrated that Cr(VI) was reduced to less harmful Cr(III) species over hollow Bi₂S₃ nanospheres under visible-light irradiation. More importantly, the hollow Bi₂S₃ nanospheres remained high efficiency and good stability in the recycling Cr(VI) photoreduction, and exhibited remarkable Cr(VI) removal ability in actual electroplating industry wastewater treatment.