Heptazine-based graphitic carbon nitride as an effective hydrogen purification membrane

Abstract

The purification of H₂ from other gases (CH₄, CO, CO₂, N₂, and H₂O) is a vital step for its safe usage. By using first-principles calculations and molecular dynamics simulations, we find that the porous graphitic carbon nitride (g-C₃N₄) monolayer works as an efficient and highly selective hydrogen purification membrane. In the DFT calculations, the transition state theory is used to search the lowest diffusion barrier (0.55 eV) for H₂ to go through the well-ordered intrinsic holes. Meanwhile, the excellent selectivity between H₂ and other gases shows that the g-C₃N₄ nanosheet is specific for diffusion of H₂. The MD simulations exhibit the whole dynamic purification process and confirm our previous DFT results. Our results indicate that the g-C₃N₄ nanosheet has great potential in separating H₂ from undesirable gases.