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Nitrogen doping γ-graphyne (γ-NGY) is a recently synthesized carbon nitride two-dimensional material with a large specific surface area and unique structure. Based on the first-principles method, the CH4 adsorption properties of γ-NGY are calculated, and a substrate structure Ti-decorated γ-NGY is designed. The results show that the center of the rhombus hole of γ-NGY is the best CH4 adsorption position, and the adsorption energy is −0.145 eV. The most stable binding position of the Ti atom on γ-NGY is also the rhombus hole. The binding energy of a Ti atom is −5.737 eV, and the average binding energy of two Ti atoms is −4.88 eV. Ti-γ-NGY successfully adsorbs 24 CH4 molecules on both sides with an average adsorption energy of −0.184 eV and the storage capacity of 69.12 wt. %. After doping N atoms, the hole size increases, and the negative charges are concentrated on N atoms. The adsorption of CH4 by γ-NGY is mainly the intermolecular force, and the adsorption energy is slightly increased. After the Ti atom transfers the negative charge to the substrate, a strong electric field is formed between the positively charged Ti atom and the negatively charged substrate. The adsorption energy of CH4 molecules near the Ti atom is greatly increased, and the Coulomb attraction between CH4 and Ti atom is dominant. The adsorption energy of the CH4 molecule far away from the Ti atom is also improved, and the intermolecular force between negatively charged substrates and polarized CH4 molecules plays a dominant role in the adsorption.

NGDY has high‐N atom doping rate, many active sites, large pore size, outstanding thermal stability, and excellent lithium‐ion storage properties. The mixed adsorption of the Mn‐modified NGDY (Mn‐NGDY) system has been studied with the first principles approach, which shows the effects and the mechanism of action about the modified Mn atom and H2 molecules on the adsorption of CH4. From the results, more electrons are transferred from the Mn atom to the neighboring six‐membered ring, making the Mn atom positively charged and forming a strong Coulomb interaction with the substrate. There is Coulomb interaction between the first two methane molecules and Mn atoms, and CH4 molecules have strong polarization phenomenon under this interaction, which causes the surrounding CH4 molecules of the first layer (The CH4 molecules around the first two CH4 molecules) inducing polarization along the XY plane (parallel substrate), and the surrounding CH4 molecules of the second layer inducing polarization along the Z‐axis direction, which improve the adsorption properties of other CH4 molecules. In the first layer, the interaction forces of the adsorbed CH4 molecules region mainly come from the interaction forces between CH4 and the substrate, and the interaction forces between CH4 molecules dominate in the adsorption of second layer. Polarization of H2 molecules along the Z‐axis direction causes the formation of a weak negative center above it, which promotes the adsorption of CH4 molecules above it. For the 2Mn‐NGDY system, a maximum of 72 CH4 molecules and 4 H2 molecules can be adsorbed simultaneously on both sides, when the average adsorption energy and adsorption amount reach −0.169 eV and 73.41 wt%.