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

- Bi2S3 hierarchical nanostructures (HNs) were fabricated by a combined synthetic strategy.
- A topotactic transformation from BiOCl microsphere to Bi2S3 HNs was proposed.
- Bi2S3 HNs displayed superior visible-light-driven Cr(VI) photoreduction capacity.
- Bi2S3 HNs were used for Cr(VI) removal in actual electroplating and tannery wastewater.

A general ionic-assisted microwave-ultrasonic combined synthetic strategy was developed to fabricate Bi2E3 (E = S, Se, and Te) hierarchitectures. To understand the crystal phase transformation and morphological evolution of Bi2S3 hierarchical nanostructures, the fabrication of Bi2S3 hierarchitectures was investigated by varying sulfidation time and chlorination time. A topotactic transformation from BiOCl microsphere to Bi2S3 hierarchitectures was proposed. It was found that the structure, size, and morphology of Bi2S3 hierarchitectures could be delicately engineered by varying chlorination time, alkyl chain length, and concentration of ionic liquid. Moreover, the as-prepared Bi2S3 hierarchitectures displayed superior capacity of Cr(VI) photoreduction to P25 and irregular Bi2S3 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 Bi2S3 hierarchitectures were also discussed. The enhancement of photoreduction capacity is not only attributed to the intrinsic good electron transfer ability of Bi2S3, 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 Bi2S3 nanospheres can be used in the actual Cr(VI)-containing wastewater treatment.

Bi2S3 hierarchitectures were fabricated by a ionic-assisted microwave-ultrasonic combined synthetic strategy and exhibited superior Cr(VI) photoreduction capacity in real industrial wastewater under visible light irradiation.105