Li-doped fullerene pillared graphene nanocomposites for enhancing hydrogen storage: A computational study

Abstract

Hydrogen physisorption in lithium doped fullerene pillared graphene nanocomposites (Li-FPGNs) having tunable pore structures were examined under different temperature and pressure conditions via grand canonical Monte Carlo (GCMC) simulations. Different forms of fullerenes and Li doping ratios, which have considerable effects on the pore structures and surface properties of FPGNs, were considered to optimize the gravimetric, volumetric and deliverable hydrogen adsorption performances of FPGNs. The GCMC simulations confirmed that the hydrogen adsorption performances of undoped FPGNs could be significantly enhanced with the appropriate selection of the doping ratio and types of fullerenes especially at ambient temperature or low-pressure conditions. Particularly, the GCMC simulations showed that the total gravimetric adsorption capacity of Li-FPGNs with doping ratio of Li:C = 15:100 could reach 9.1 wt% at 77 K and 1 bar, which corresponds to about two times increment in the hydrogen storage performance of undoped FPGNs. Moreover, the GCMC simulations demonstrated that Li doping could enhance the excess hydrogen storage capacity of FPGNs up to three times at ambient temperature. These results revealed that Li-FPGNs are promising candidates in the field of hydrogen storage.