Ionic liquid-employed synthesis of Bi2E3 (E = S, Se, and Te) hierarchitectures: The case of Bi2S3 with superior visible-light-driven Cr(VI) photoreduction capacity

A general ionic-assisted microwave-ultrasonic combined synthetic strategy was developed to fabricate Bi 2 E 3 (E   =   S, Se, and Te) hierarchitectures. To understand the crystal phase transformation and morphological evolution of Bi 2 S 3 hierarchical nanostructures, the fabrication of Bi 2 S 3 hierarchitectures was investigated by varying sulfidation time and chlorination time. A topotactic transformation from BiOCl microsphere to Bi 2 S 3 hierarchitectures was proposed. It was found that the structure, size, and morphology of Bi 2 S 3 hierarchitectures could be delicately engineered by varying chlorination time, alkyl chain length, and concentration of ionic liquid. Moreover, the as-prepared Bi 2 S 3 hierarchitectures displayed superior capacity of Cr(VI) photoreduction to P25 and irregular Bi 2 S 3 nanostructures under visible light irradiation. Effects of morphology, pH value of reaction system, Cr(VI) concentration, and catalyst dosage on the Cr(VI) photoreduction capacity of Bi 2 S 3 hierarchitectures were also discussed. The enhancement of photoreduction capacity is not only attributed to the intrinsic good electron transfer ability of Bi 2 S 3 , but also to synergetic effects of special architectures, wide photoresponse range, high light photoadsorption, high BET surface area and good electron-hole separation performance. The systematic condition experiments and Cr(VI) photoreduction in electroplating and tannery wastewater experiments further demonstrated that the hierarchical Bi 2 S 3 nanospheres can be used in the actual Cr(VI)-containing wastewater treatment.