A p–n heterostructural g-C3N4/PANI composite for the remediation of heavy metals and organic pollutants in water

Abstract

A novel graphitic carbon nitride/polyaniline (g-C₃N₄/PANI) composite was successfully fabricated, which showed excellent photocatalytic performance towards the reduction of Cr(VI) and degradation of MO (methyl orange) under visible-light. PANI not only acted as a light acceptor to produce photogenerated electrons but also as a conductive polymer to boost the migration of charge carriers, leading to an improvement in photocatalytic activity. Using multiple characterization techniques and optical and photoelectrical measurements, the improved photocatalytic performance was ascribed to the g-C₃N₄/PANI p–n heterostructure and integration of the merits of its individual components. The optimal g-C₃N₄/PANI_5.0 exhibited excellent Cr(VI) reduction activity (93.7% for 120 min), which was 21-times higher than that of the pristine g-C₃N₄ under visible-light. Furthermore, g-C₃N₄/PANI_5.0 showed high MO degradation activity and also excellent mineralization capability (68.0% TOC removal for 75 min), and its degradation rate (98.2% for 75 min) was 33.9- and 14.7-times higher than that of PANI and g-C₃N₄, respectively. Finally, possible photocatalytic enhancement mechanisms for the reduction of Cr(VI) and degradation of MO were proposed under visible light based on the optical and electrochemical performances.