One-pot synthesis of 3D porous Bi7O9I3/N-doped graphene aerogel with enhanced photocatalytic activity for organic dye degradation in wastewater

The compound Bi7O9I3 has been considered as a promising candidate for organic dye degradation in wastewater, but it has relatively low photocatalytic activity and difficulties in the recycling processes. In this work, a novel floating 3D porous Bi7O9I3/N-doped graphene aerogel (Bi7O9I3/NGA) composite was successfully synthesized through a facile hydrothermal route. The Bi7O9I3/NGA composite exhibited highly enhanced photocatalytic performance toward degrading rhodamine B under visible-light irradiation, which increased 6.0 and 2.3 times compared with the Bi7O9I3 and Bi7O9I3/GA, respectively. The enhancement of photocatalytic degradation activity could be ascribed to the extensively promoted charge generation and migration efficiency, visible light utilization ability and reactive oxygen species production. Besides, the special 3D macroscopic block structure of Bi7O9I3/NGA allowed it to float, making it easy to recycle. The photocatalytic degradation efficiency of Bi7O9I3/NGA composite still could reach up to 92.7% after four consecutive cycles and presented satisfactory stability and reusability. Moreover, a possible photocatalytic degradation mechanism was revealed by radical species trapping and semi-quantitative analyses experiments.