Nitrogen-doped coronene for enhanced CH4 and CO2 adsorption: A theoretical study

Activated carbon is a highly effective material for carbon capture and storage, primarily due to its affordability and large surface area. In this work, we use density functional theory (DFT) to examine the impact of nitrogen doping on the CO₂ and CH₄ adsorption properties of coronene, a potential precursor for activated carbon. We explore five different nitrogen-doped configurations: graphitic, pyridinic, pyrrolic, pyrazole, and amine. Our results show that all examined defect types enhance the adsorption energies for both CO₂ and CH₄, which can be attributed to improved orbital overlap and hybridization between the organic molecules and the substrate. Graphitic nitrogen exhibits the strongest adsorption mode for methane molecules, while pyridinic nitrogen demonstrates the most effective adsorption for carbon dioxide. For all the samples considered, the CO₂ molecule exhibits stronger adsorption energy compared to the CH₄ molecule, due to its polar nature which increases its affinity for the doped sites. In addition to DFT calculations for adsorption energies, the density of states, and charge density differences, we have also conducted force-field-based molecular dynamics simulations to investigate the adsorption process of the considered gas molecules. The presence of water significantly modifies the interaction of gas molecules with the substrate highlighting the importance of environmental conditions in gas capture performance. These findings could have practical significance for the development of selective carbon capture systems based on activated carbon.