Computational prediction of experimentally possible g-C3N3 monolayer as hydrogen purification membrane

• The structure of g-C3N3 monolayer was optimized, and its stability was confirmed.
• The energy barrier for H2 penetrating through g-C3N3 layer is so low that high H2 permeability can be ensured.
• The g-C3N3 layer exhibits high selectivity of H2 vs. CO, N2, and CH4, and is a promising hydrogen purification membrane.

Membrane technology has been used for hydrogen purification. In this work, two-dimensional g-C3N3 monolayer was proposed as an effective hydrogen separation membrane on basis of density functional theory computations. The structure of g-C3N3 monolayer was optimized first, and the computed phonon dispersion confirmed its stability and supported the experimental feasibility. The permeability of H2 and impurity gases, including CO, N2 and CH4, was investigated. Compared with H2, it is more difficult for the impurity gases to penetrate through g-C3N3 monolayer. The high selectivity of H2 vs. CO, N2, and CH4 ensures a superior capability to conventional carbon and silica membranes. With high H2 permeability and selectivity, g-C3N3 monolayer is a potential H2 purification membrane.

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