Adsorption ability of pristine C24N24 nanocage promising as high hydrogen storage material: A DFT-D3 investigation

Adsorption of eight numbers of H-2, (H-2)(n) where n = 1, 2, 4, 6, 8, 12, 18, 24, adsorbed on the C24N24 nanocage (CNNC) surface was investigated using three different DFT methods. Adsorption energies of various numbers of H(2 )adsorbed on the CNNC surface were obtained. Adsorption strength of the CNNC was found depending on the adsorbed H-2 numbers and is in order: the H-2 numbers of (H-2) > (H-2)(2) > (H-2)(4) > (H-2)(6 )> (H-2)(8 )> (H-2)(12) > (H-2)(18) > (H-2)(24). The most stable adsorption configuration of (H-2)(12)/CNNC, all adsorbed H2 molecules formed as the full monolayer (ML) coverage, are dissociative chemisorption. The bilayer of (H-2)(24)/CNNC was found that the first and second layers are composed of 12H(2 )as dissociative chemisorption and 12H(2) as physisorption, respectively. The high hydrogen storage capacity of the CNNC formed as (H-2)(24)/CNNC, around 7.75 wt% was found. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The adsorption behavior of hydrogen molecules on the surface of C24N24 nanocage was studied using three different DFT methods. The adsorption strength was found to depend on the number of hydrogen molecules adsorbed. The most stable adsorption configuration was observed to be a fully covered dissociative chemisorption, and a bilayer structure was also observed. The (H-2)(24)/CNNC system showed a high hydrogen storage capacity.