Density Functional Study of Physisorption of H 2 Molecules on Scandium and Yttrium Decorated C 20 Fullerene: Prospect for Hydrogen Storage

Abstract This work reports the findings of a study on the reversible hydrogen storage capacities of Sc and Y decorated C20 fullerene, conducted using dispersion corrected density functional theory (DFT) calculation. The transition metal (TM) atoms, such as Sc and Y, are identified to attach to the C-C bridge position of the C20 fullerene through non-covalent closed-shell interactions. This suggests that the interaction between the TM atoms and the fullerene occurs via weak van der Waals forces rather than stronger covalent bonds. And the thermodynamic stability of the decorated fullerene structures is assessed using various methods, including the examination of HOMO-LUMO gaps and different reactivity descriptors. These analysis help confirm that the decorated structures are stable under the given conditions, enhancing their suitability for hydrogen storage applications. Each Sc and Y atom attached to the C20 fullerene is capable of absorbing a maximum of 6 and 7 hydrogen molecules, respectively. This results in practical gravimetric densities of up to 4.0 wt% and 4.04 wt% at a temperature of 300K and a pressure of 60 bar. These findings highlight the significant hydrogen storage capacities of the decorated fullerene structures, indicating their potential for practical use in hydrogen storage systems. The average adsorption energy of H2 molecules are found lying in the range of 0.332eV-0.276eV implying the adsorption process to be physisorptive. Overall, the study provides valuable insights into the hydrogen storage capabilities of Sc and Y decorated C20 fullerene complexes, offering a promising avenue for the development of efficient and reversible hydrogen storage materials for clean energy applications.