Highly efficient visible-light induced N-doped ZnO@g-C₃N₄ and S-doped ZnO@g-C₃N₄ photocatalysts for environmental remediation

Abstract

Facile, cost-effective and eco-friendly synthesis of N-doped ZnO@g-C₃N₄ and S-doped ZnO@g-C₃N₄ photocatalysts towards efficient degradation of environmental pollutants was achieved. The as-synthesized 2 wt% N-doped ZnO@g-C₃N₄ and 2 wt% S-doped ZnO@g-C₃N₄ achieved 96.2% and 90.4% degradation efficiencies towards crystal violet (100 ppm) within 45 min irradiation and 99.3% and 92.3% photocatalytic degradation efficiencies towards brilliant green (100 ppm) dye within 30 min irradiation, respectively, under a normal 90 W LED light instead of an expensive commercial light source. Moreover, the N-doped ZnO@g-C₃N₄ and S-doped ZnO@g-C₃N₄ nanocomposites showed excellent stability in the photodegradation of crystal violet and brilliant green dyes. The modification made on ZnO by doping with nitrogen and sulphur enhances the visible-light absorption as well as the separation of photoexcited charge carriers. The active radicals ˙OH and ˙O₂^- are both identified to play important roles in the photodegradation of crystal violet and brilliant green.