Abstract:
The need for sustainable energy fuel is much
higher than before. The use of hydrogen as a fuel is impeded
due to its low storage capacity in the storage medium. In this
work, a newly designed metal−carbyne framework (MCF) is
decorated with Li atoms with an average Li binding energy of
1.94 eV. Two Li atoms are used to decorate each carbyne
linker of the MCF. Here, using density functional theory
calculations, we systematically investigated the adsorption of
H2 in Li-decorated MCF, namely MCFLi8. It is found that
four H2 molecules are adsorbed in the molecular form on each
Li in MCFLi8 by Niu’s charge polarization mechanism. Our
findings revealed that the Li-decorated MCF exhibits a high
hydrogen storage capacity at ambient conditions with
adsorption−desorption energy ranging between 0.2 and 0.6 eV. Hirshfeld charge analysis and electrostatic potential maps
show the charge transfer mechanism during the hydrogen adsorption. Born−Oppenheimer molecular dynamics simulations
reveal the reversibility of adsorbed hydrogen at ideal pressure and temperature conditions. Thermodynamic usable capacity of
adsorbed hydrogen at adsorption and desorption conditions is determined by calculating hydrogen occupation number. The
gravimetric hydrogen density of 11.1 wt % is found for complete H2 adsorbed in MCFLi8. This study suggests that Li-decorated
MCF can be a promising hydrogen storage material.
