High yield synthesis of homogeneous boron doping C3N4 nanocrystals with enhanced photocatalytic property

Carbon nitride (C3N4) has attracted widespread attention in the photocatalysis field for its stability, facile preparation from low-cost materials, and outstanding visible-light activity. Exploring novel synthesis or modification approaches of C3N4 with excellent photocatalytic property is still a research hotspot in this area. Herein we report a high-yield synthesis of C3N4 and boron-doped C3N4 using the mixed salts KCl-NaCl-LiCl as solvent. Compared with C3N4 sample prepared by the traditional solid-state reaction method, the sample by the molten-salt process showed much better photocatalytic activity for the degradation of methyl orange solution under visible light, which should be originated from high crystallinity and large surface areas as demonstrated by XRD, TEM and BET results. Furthermore, the photocatalytic activity of the molten-salt prepared C3N4 samples was regulated by boron doping, and the best photocatalytic performance was found at the boron content of 0.5%. Moreover, the photoluminescence properties of the samples were also investigated. The relationship between the photoluminescent and photocatalytic performances of the samples were compared and discussed. We believe the synthetic approach reported here provides a new strategy toward the homogeneous doped C3N4-based materials.