A First-principles Study Of Gas Molecules Adsorption On Graphene And Hydrogen-substituted Graphdiyne

Human survival and development are based on the possession of a large amount of energy.However,traditional energy fuels are non-renewable,and a large amount of harmful gases are generated during combustion.Therefore,energy and environmental problems are inevitable and urgent problems to be solved on the development path of human society.Hydrogen energy has become one of the new energy sources replacing fossil fuels due to its abundant reserves and clean products.Its safe and effective storage has become a hot issue for research.At the same time,the adsorption and detection of harmful gases generated by the combustion of traditional fuels are also important fields of scientific research.Porous graphene?PG?and hydrogen-substituted graphdiyne?HsGDY?have great potentials in terms of hydrogen adsorption and harmful gas adsorption due to their large specific surface area and porous position.PG composed of three C₆H₂ rings has become a new type of hydrogen storage carbon material due to its large specific surface area and pore size,which can provide sufficient adsorption sites.The storage performance of H₂ on Sc-modified PG?Sc-PG?was studied using density functional theory.The results show that the optimal adsorption position of a single Sc atom on the PG is the central pore position.The modification of the Sc atom increases the adsorption energy of H₂,the average adsorption energy is-0.238 eV,and it can adsorb 9 H₂.The optimal adsorption position of two Sc atoms modified on both sides of PG is symmetrical adsorption at the central pore position.The system can adsorb up to 40 H₂molecules,which are attracted by Sc atoms in a hemispherically symmetric manner,and the adsorption capacity is up to 20.530 wt.%.The average adsorption energy is-0.117 eV.The adsorption of the system with H₂ molecules is mainly the Kubas interaction and Coulomb attraction between the negatively charged H₂ molecules and the positively charged Sc atoms.There are two types of polarization after H₂ molecules are adsorbed.The inner H₂ molecules are polarized perpendicular to the H-H bond direction and adsorbed parallel to the PG plane;the outer H₂ molecules are polarized along the H-H bond direction and adsorbed to the vertical PG plane.HsGDY is a novel alkynyl carbon material with a structure similar to that of graphene.In this paper,the adsorption of four gas molecules?NO,NO₂,NH₃,and N₂?on HsGDY and B-doped HsGDY?B-HsGDY?was studied using density functional theory.The results show that the adsorption of NO and NO₂ on HsGDY and B-HsGDY is characterized by a larger charge transfer,stronger interaction,and higher adsorption energy compared with that of NH₃and N₂.Based on the doping with B atoms,the adsorption energies of the gas molecules on HsGDY significantly improve,especially that of NO and NO₂.The gas molecule adsorption on both HsGDY and B-HsGDY is physical adsorption and the adsorption selectivity is good and thus may be applied for gas-sensitive NO and NO₂ materials.