In situ construction efficient visible-light-driven three-dimensional Polypyrrole/Zn3In2S6 nanoflower to systematically explore the photoreduction of Cr(VI): Performance, factors and mechanism

Abstract

Photoreduction of highly toxic Cr(VI) has been regarded as an efficient and green method to achieve water purification. In this process, better charge carrier separation is vital to achieving excellent performance. Besides, it is vital to systematically explore the influencing factors and reaction mechanism. Herein, a novel 3D PPy/Zn₃In₂S₆ nanoflower composite was successfully fabricated via in-situ polymerization. The remarkable conductivity of PPy provides a good electron transport path to facilitate the separation and migration of charge carriers, which benefits to the activity improvement. The results show that 5% PPy/Zn₃In₂S₆ exhibits superior photocatalytic activity with almost 100% Cr(VI) reduction just within 24 min and 99.4% of Methyl orange (MO) is degraded in 25 min. On this basis, factors of different catalyst dosage, concentration, ions and pH under the reduction system were systematically investigated. Especially, different organic acids were in-depth analyzed and the activity could be significantly enhanced just adding 0.1 mmol organic acids. 5% 3D PPy/Zn₃In₂S₆ nanoflower composites (with tartaric acid) exhibits superior photocatalytic activity, which can achieve 100% photoreduction of Cr(VI) just within 6 min. Finally, a possible reaction mechanism was proposed. Moreover, 3D PPy/Zn₃In₂S₆ nanoflower also presented an efficient photodegradation activity for organic pollution.

Keywords: Chromium; Organic acids; PPy/Zn(3)In(2)S(6); Photocatalyst.