Gas sorption, storage and separation in carbon materials are mainly based on physisorption on the surfaces and particularly depend on the electrostatic and dispersion (i.e., vdW) interactions [Progress in Materials Science 69, 1–60, (2015)]. The former can be tuned by introducing charge variations in the material, and the latter by chemical substitution. The surface modifications, such as doping, functionalization and improving the pore structure and specific surface area of nanocarbons, are important to enhance gas adsorption. Recently, the successful synthesis of nitrogenized porous graphene monolayer, C₂N, has attracted great interest in the development process of designing new materials [Nat. Commun. 6, 6486, 2015]. First, it exhibits an extremely high thermal stability, which can resist temperatures close to 700 °C. It also has a tunable wide range band gap, implying its possible applications in electronic and optoelectronic devices. Due to the larger electronegativity of the nitrogen atom in the C−N bonds, there are intrinsic electron transfers in the C₂N monolayer. This electron redistribution is expected not only to increase the solubility of C₂N, which is an important feature desired for its sensor usage, but also to engender distinctive properties that are absent in a pristine graphene surface. Considering the goal of reducing CO₂ emission and efficient conversion, it is necessary to find high-capacity adsorbents along with low-temperature desorption properties for regenerative CO₂ capture.In this proposal our emphasis is to explore the role of functionalised N-rich porous material in CO₂ capture using density functional theory. However, there are very few investigations for functionalised C₂N monolayer as a CO₂₀gas sensor as well CO₂ gas storage[Phys.Chem.Chem. Phys. 19,28323, 2017]. The functionalization of C₂N layer can be considered by doping metal atoms.