The properties and mechanism of adsorption of hydrogen
molecules
on NLi4-decorated graphdiyne nanosheets (NLi4-GDY) were investigated based on the density functional theory. Accordingly,
the 76 hydrogen storage configurations of NLi4-SGDY, NLi4-GDY-A, and NLi4-SGDY-A were constructed by nonmetallic
B/N substitution and A (A = B, N, Si, P) adsorption. The electronic
structure of each configuration and the structure with the desired
high hydrogen storage capacity were explored. The results showed that
the charge on the lithium atom in the NLi4-GDY structure
was transferred to the pristine GDY, thus forming a partial electron
field around each lithium atom, which subsequently led to the polarized
adsorption of the hydrogen molecule. Through B/N substitution and
A adsorption, we have modulated the degree of charge transfer in Li
atoms across different configurations, thereby manipulating the strength
of partial electric fields and resulting in varying hydrogen storage
capacities for NLi4-SGDY, NLi4-GDY-A, and NLi4-SGDY-A configurations. According to DFT calculations, the
optimal hydrogen storage structures for NLi4-GDY, NLi4-SGDY, NLi4-GDY-A, and NLi4-SGDY-A were
6H2-2NLi4-GDY, 14H2-2NLi4-N11′, 14H2-2NLi4-GDY-Si, and 18H2-2NLi4-N1-P, respectively, with gravimetric densities
of 3.85, 8.09, 7.29, and 8.91 wt %, respectively. Considering the
exceptional hydrogen storage properties of the aforementioned configurations,
we propose that NLi4-decorated GDY with B/N substitution
and A adsorption offers a promising avenue for discovering novel hydrogen
storage materials.