Supporting Information
A first-principles study of lithium-decorated hybrid boron nitride
and graphene domains for hydrogen storage
Zi-Yu Hu,1,2 Xiaohong Shao,1,* Da Wang,2 Li-Min Liu2,*J Karl Johnson 3
1
College of Science, Beijing University of Chemical Technology, Beijing 100029,
People's Republic of China
2
Beijing Computational Science Research Center, Beijing 100084, People's Republic
of China
3
Chemical of Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
Li clustering: The Li clustering is an important issue during the process of hydrogen
storage. In order to make this point clearly, we have made some further calculations to
check this. In this kind of calculations, three typical complexes of(BN )0.25C 0.75 ,
B 0.125C 0.875 along with pure graphene are employed and discussed. The first system of
(BN )0.25C 0.75 has the highest hydrogen storage amount, on the other hand, the Li
clustering of
B 0.125C 0.875 and pure graphene complexes are recently more reported.
By comparing the binding energies, it is found that of the two isolated Li atoms on the
4  4 (BN )0.25C 0.75 cell are more stable than that of two dimerized Li atoms. The
calculated results in Fig.S1 show that, for the (BN )0.25C 0.75 structure, the isolated
configuration is energetically more favorable by 0.34 eV (  E= 0.34 eV), while, for
the B 0.125C 0.875 and pure graphene complexes. The isolated configuration is more
stable by 0.23 eV and 0.13 eV. The calculated results show that Li decorated
（BN）
0.25C 0.75 system has the largest difference of binding energies between the
isolated and dimerized configurations indicating that it is more difficult for Li
clustering than the other two complexes, therefore, it should be the most stable system
for preventing Li clustering of the three substrates. It may results from the long
distance of Li-Li, the relative strong bonding between the metal atoms and the
(BN )x C 1 x substrates leading to the prevention of metal clustering on the substrates.
Fig. S1 (Color online) Optimized structures of dimerized and isolated Li atoms
adsorbed on
(BN )x C 1  x for (a) x=0.25, (b) B 0.125C 0.875 (c) x= 0, sheets. Our
calculations show that in these structures the isolated configuration is energetically
more favorable by 0.34, 0.23 and 0.13 eV than the dimerized configuration.
vdW corrections: The application of the vdW corrections in DFT is applied to
systems where the bonding at some interface is dominated by van der Waals forces,
i.e fluctuations in charge density at the interface. Often such corrections are necessary
when studying anything from molecular crystals to solids and quite often depend on
the material/system being studied.
Using vdW corrections, we calculated the hydrogen adsorption for the systems
of pure graphene and (BN )0.25C 0.75 . For the pure graphene complex, the adsorption
energies of 1H2, 2H2, 3H2 and 4H2 are 0.15, 0.35, 0.22, 0.21 eV, while the LDA
results are 0.18, 0.27, 0.23, 0.22 eV, respectively. It is noted that only the first 1H2
adsorption energy is a bigger than the published one, due to the most stable adsorption
site is bridge-site not top-site, which is the novelty of this work. For the (BN )0.25C 0.75
complex, the adsorption energies of 1H2, 2H2, 3H2, 4H2 and 5H2 are 0.26, 0.28, 0.24,
0.11, 0.10 eV, while the LDA results are 0.25, 0.28, 0.26, 0.08, 0.08 eV, respectively.
The more details are listed on Table S1. We also use the vdW corrections to check
the most stable adsorbed sites of 1H2 on the substrate. The calculated results show
that the most stable adsorbed sites are not changed. It can be concluded that the
difference between two functional methods is not apparent, and which does not
influence the most stable adsorption sites and the adsorption amount. Thus our
benchmark calculations suggest that the results with LDA are reliable compared with
those with the corresponding functional with vdW corrections.
Table S1 The calculated adsorption energies of 1H2, 2H2, 3H2, 4H2 and 5H2 on the graphene and
( BN ) 0.25 C0.75 complexes using vdW corrections and LDA.
Complexes
Adsorbed
energy of
1H2
Adsorbed
energy of
2H2
Adsorbed
energy of
3H2
Adsorbed
energy of
4H2
Adsorbed
energy of
5H2
Graphene-vdW
0.15
0.35
0.22
0.21
--
Graphene-LDA
0.18
0.27
0.23
0.22
--
( BN ) 0.25 C0.75 -vdW
0.26
0.28
0.24
0.11
0.10
(BN )0.25C 0.75 -LDA
0.25
0.28
0.26
0.08
0.08