Synthesis of crystalline g-C3N4 with rock/molten salts for efficient photocatalysis and piezocatalysis

Abstract

Graphitic carbon nitride (g-C3N4) is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics significantly restricts its practical applications. Currently, synthesizing highly crystalline g-C3N4 with sufficient surface activities still remains challenging. Herein, different from using alkali molten salts which is commonly reported, we propose an approach for synthesis of highly crystalline g-C3N4 with FeCl3/KCl rock/molten mixed salts. The rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for re-condensation. Intriguingly, the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high π→π∗ excitation compared with crystalline C3N4 prepared from conventional molten-salt methods. These catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C3N4. This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.