▎ 摘　　要

Porous graphene (PG) has a promising future for gas storage owing to its unique pore characteristics and large specific surface area. The adsorption properties of PG and Mn atoms decorated PG (Mn-PG) for methane (CH4) molecules have been studied based on the first-principles density functional theory. It is discovered that the optimum adsorption position of CH4 on PG is the carbon ring pore, and the adsorption energy is - 0.174 eV. The optimal position of the PG system decorated by single Mn atom is the central hole of the carbon ring, and the optimal position of the two Mn atoms is that Mn atoms are, respectively, located at different carbon ring holes on the opposite side of PG, with an average binding energy of - 4.101 eV. The modification of the Mn atom enhances the electronegativity of the PG substrate and forms a negative electrical center at the carbon ring, which facilitates the enhancement of the adsorption performance of the CH4 molecules that are positively charged with the surface. The CH4 molecule, close to Mn atom shows negative charge, and its strong electrostatic interaction with positively charged Mn atom is dominant, resulting in higher adsorption energy. The surface of CH4 molecule far away from the Mn atom is positively charged, the weak electrostatic interaction with the negatively charged PG substrate and the Van der Waals interaction between CH4 molecules are dominant, and the adsorption energy is low. The CH4 molecules are adsorbed on the PG surface through the electrostatic interaction with Mn atoms and PG substrate as well as the intermolecular force of CH4 molecules. The Mn-PG system is single-sided adsorption 6 CH4 molecules, and the average adsorption energy is - 0.345 eV. When two Mn atom modification PG, 12 CH4 molecules can be adsorbed on both sides, and the average adsorption energy is - 0.338 eV, the adsorption capacity is up to 38.43 wt.%.