Dissolution of g-C3N4 Using Zinc Chloride Molten Salt Hydrates for Nanobelt Fabrication and Photocatalytic H2O2 Production

Graphitic-carbon nitride (g-C3N4), a metal-free two-dimensional layered semiconductor material, holds great potential for energy conversion, environmental remediation, and sensing. However, the limited solubility of g-C3N4 in conventional solvents hinders its widespread application. Improving the dissolution of g-C3N4 in the liquid phase is highly desired but challenging. Herein, we report an innovative approach to dissolve g-C3N4 using ZnCl2 molten salt hydrates. The solubility of g-C3N4 in the solution reaches up to 200 mg mL(-1). Density functional theory (DFT) results suggest that ZnCl+H2O is the key species that leads to charge redistribution on g-C3N4 surface and promotes the dissolution of carbon nitride in the solution. Furthermore, through dilution, the dissolved carbon nitride can be effectively recovered while maintaining its intrinsic chemical structure. The resultant regenerated C3N4 (r-C3N4) exhibits nanobelt morphology and demonstrates a substantially improved photocatalytic activity in H2O2 production. The rate of H2O2 production over the r-C3N4 reaches 20,228 mu mol g(-1) h(-1), which is 6.2 times higher than that of pristine g-C3N4. This green and efficient dissolution route of g-C3N4 offers an effective approach for its diverse applications.