Construction of graphitic carbon nitride nanosheets via an improved solvent exfoliation strategy and interfacial mechanics insight from molecular dynamics simulations

Graphitic carbon nitride (g-C3N4) nanosheets have attracted great attention in the areas of photocatalysis, sensors, energy storages and membrane separations. A three-step exfoliation strategy was designed to use solvent exfoliating g-C3N4 nanosheets from bulk g-C3N4. In the first stage, bulk g-C3N4 was prepared and then exfoliated into g-C3N4 nanosheets by various solvents. In the second stage, molecular dynamics simulations were carried out and the energy barriers for the exfoliations were determined. Various interactions between solvent molecules and exfoliated nanosheet were analyzed. In the third stage, exfoliation was re-carried out according to the result from MD simulation to obtain optimal amount of exfoliated g-C3N4 nanosheets. The experimental result matched with the simulation prediction very well. In combination with simulation and experiment, a successful way to obtain maximum amount of exfoliated g-C3N4 nanosheet was set up. Then a 5.03 mg/mL g-C3N4 suspension was obtained. Meanwhile, a concept of kinetic energy increment was introduced for the first time to explain the exfoliating efficiency of g-C3N4 nanosheets, which greatly reduced the simulation time by 80% compared with the free energies in terms of the potential of mean force.