Adsorption of H2, CH4, and their mixture on Na-decorated [1, 1]Paracyclophane: An atomistic approach

We present a computational investigation of Na-decorated [1,1]Paracyclophane for onboard storage of hydrogen, methane, and their mixtures, in accordance with Department of Energy (DoE) regulations. The binding energy calculation (0.635 eV) reveals that the Na atom binds with the substrate loosely. It is found that Na-decorated PCP11 can reversibly adsorb up to 10 hydrogen molecules and 8 methane molecules, as well as other different proportions of their mixtures, with an average adsorption energy of 0.125 eV/H 2 and 0.195 eV/CH 4 through a Niu-Rao-Jena type interaction. The computed gravimetric capacities of hydrogen and methane are 8.18 wt% and 36.19 wt%, respectively, meeting the DoE's requirements. The charge polarization mechanism during the adsorption process is investigated using the PDOS, ESP, and Hirshfeld charge analysis. The maximum desorption temperatures of the hydrogenated system are 235.26 K and 316.11 K for the methane adsorbed system. Molecular dynamics simulations confirm the stability and reversibility of the host structure, with no structural distortion. • The gas molecules are adsorbed on Na-decorated PCP11 by the quasi-molecular type. • The adsorption energy of H 2 molecules varies from 0.1 eV to 0.15 eV, and CH 4 0.18- 0.20 eV, respectively. • Co-mixing of hydrogen and methane increases the adsorption of individual gases. • The gravimetric capacity of hydrogen and methane is 8.18 wt% and 36.19 wt%, respectively.