Facile fabrication of a Z-scheme g-C3N5/Gd-MOF/silver nanocube composite as a new generation visible light active photocatalyst for abatement of persistent toxic pollutants†

Abstract

Some of the persistent hazardous contaminants that readily dissolve in water with a recognizable hue are hexavalent chromium and neomycin antibiotic. Herein, a Z-scheme g-C₃N₅/Gd-MOF/silver nanocube (CNGdAg) ternary composite was successfully designed by the combination of graphitic carbon nitride (g-C₃N₅), gadolinium-based molecular organic framework (Gd-MOF), and silver nanocubes (AgNCs). Under visible light irradiation, CNGdAg outperforms individual components and binary composites in the photoreduction of hexavalent chromium (Cr⁶⁺) and removal of neomycin. The maximum photocatalytic efficiency of Cr⁶⁺ (98%) in 150 minutes and complete neomycin removal in 25 minutes were accomplished by the CNGdAg-40% composite. A hydrothermal approach was chosen to prepare this visible light active composite. The formation of photogenerated electrons and superoxide radicals plays a major contributing factor in the efficient degradation in a short period without using any external components. The combined effect of the individual components in the composite led to the remarkable degradation via the Z-scheme pathway. This work exemplifies that the CNGdAg-40% photocatalyst can be used for the removal of heavy metal ions and organic contaminants from aquatic environments.