It is critical to design an effective two-dimensional membrane for hydrogen purification from the mixed gas,due to its wide range of scientific and industrial applications.In this work,we investigate the hydrogen separation performance of P2C3 membranes by density functional theory and molecular dynamics simulations.The results show that the energy barrier of the H2 molecule through the P2C3 film is only 0.18 eV,while the energy barriers of the CO,N2,CO2,and CH4 molecules are 0.77 eV,0.87 eV,0.52 eV,and 1.75 eV,respectively.In addition,the P2C3 film has high H2 selectivity toward other gas molecules and high H2 permeability at room temperature.Under 6％ tensile strain,82％ hydrogen molecules pass through the film with a H2 permeance of 2.22 × 107 gas permeance unit (GPU),while other molecules cannot across the membrane at all.Therefore,the P2C3 membrane is an excellent material for hydrogen purification.