To maximize reversible H_2 storage near room temperature and modest pressures, we propose Li doping of the metal-organic framework (MOFs) structures developed by the Yaghi group at UCLA (constructed using octahedral Zn−O−C clusters with aromatic carbon ring linkers). We tested this design using grand canonical Monte Carlo simulations with first-principles derived force fields and predict that at −30 °C and 100 bar the Li−MOF-C30 leads gravimetric H_2 uptake of 6.0 wt %, reaching the 2010 Department of Energy target (6.0 wt % in the temperature ranges of −30 to 80 °C and pressures ≤100 bar). Thus this promising material for practical hydrogen storage is worthy of developing experimental procedures for synthesis and characterization

Goddard, William A., III

Han, Sang Soo

Caltech Authors - Main

 S1 
Supporting Information  
“Li-Doped Metal Organic Frameworks for Reversible H2 Storage at 
Ambient Temperature" 
Sang Soo Han, and William A Goddard III 
Materials and Process Simulation Center, Division of Chemistry and Chemical 
Engineering, California Institute of Technology, Pasadena. CA, 91125 
The supporting material is organized as follows: Section 1 describes quantum mechanics 
calculation details and more results. Section 2 describes the force fields derived from ab-initio 
calculations and section 3 shows H2 adsorption isotherms in gravimetric and volumetric units 
of Li-doped metal organic frameworks (MOFs) at 273 and 300 K. 
S.1. Quantum mechanics calculation of van der Waals interaction parameters 
DFT methods are well known to lead to poor descriptions of the London dispersion 
attractive terms dominating weakly bound van der Waals molecules. Hence, DFT is not useful 
for predicting exact interaction energies between dihydrogen and the organics of MOFs. 
Therefore, we optimized all coupled clusters using the second-order Møller-Plesset (MP2) 
calculations with the approximate resolution of the identity (RI-MP2) [1,2]. These calculations 
were carried out with the TURBOMOLE program [2].  
For H2 on benzene, we used the triple zeta valence basis (TZV) [3] supplemented with 
polarization functions from the cc-pVTZ basis [4], which is denoted as TZVPP (the 1s 
electrons of the C and O atoms are not correlates, frozen-core approximation). The binding 
energy of H2 with benzene was corrected for basis-set superposition error (BSSE) by the full 
counterpoise procedure. In addition, the appropriate auxiliary-TZVPP basis set was used for the 
RI-MP2 calculations [5].  
In the case of H2-MOF clusters, the geometries were optimized up to the RI-MP2/TZVPP 
level of theory with frozen cores in all cases.  Then single point energies were calculated using 
RI-MP2 with the quadruple zeta QZVPP basis. Here we did not use BSSE corrections, since 
this has been shown not to be necessary for Zn-MOF cluster [6].   
The QM calculated H-H bond length, 0.74 Å, is comparable to the experimental value of 
0.75 Å for free H2 molecule [7]. Moreover, the QM vibration frequency of H2 is 4224 cm-1, 
which is close to the experimental value of 4400 cm-1 for free H2 [7]. We calculate the H2 
binding energy with the Zn containing cluster to be -1.49 kcal/mol (Table S1), in good 
agreement with the result of -1.51 kcal/mol from Ref. [6]. 
 S2 
Table S1. QM data (RI-MP2, energies in Hartree) and force field data (energies in kcal/mol) for 
binding of an H2 molecule to the metal oxide cluster and to the benzene ring.  
 Zn cluster- H2 a Benzene- H2 b 
H2 -1.166651 -1.164698 
M4O(CO2)6H6 -8322.821264 -231.733624 
M4O(CO2)6H6-H2 -8323.990283 -232.899789 
Binding energy -1.49 -0.91 
Force field -1.48 -0.91 
aQZVPP basis set 
bTZVPP basis set 
 S3 
 S.2 Fitting of the Force Field  
We used QM calculations to determine interaction potential of H2 with the metal 
sites and organic linkers of the MOF with different. Then we fitted these results to obtain 
Morse pair potentials (Eq. (1)) between each atom of H with the MOF 
 
⎪⎭
⎪⎬
⎫
⎪⎩
⎪⎨
⎧
−⋅−−= )]1(
2
exp[2)]1(exp[)(
or
ijr
or
ijrDijrUij
αα
            (1) 
Here the parameters D is the well depth, r0 is the equilibrium bond distance, and α determines 
the stiffness (force constant).  
For the C-H cross term, we carried out RI-MP2/TZVPP calculations for the interaction between 
H2 and C6H6 molecules as shown in Fig. S1.  
  
Figure S1. Comparison of the quantum calculations and fitted force fields for H2 interacting 
with C6H6. In these calculations, the H2 was oriented vertically to the C6H6 ring and the 
distance between the bond midpoint of H2 and the center of the benzene were varied.  
 
For the interactions of H2 with the metal site in MOF, we carried RI-MP2/QZVPP calculations 
for clusters such as Zn4O(CO2)6H6+H2 in Table S1. And the optimized structures are indicated 
in Table S2. 
To determine the interactions of H2 with the Li bonded to an aromatic hydrocarbon we 
considered one H2 bonded to a planar C32 cluster (ten aromatic rings) doped with one Li atom 
on each side [8]. These calculations used the X3LYP flavor of DFT with the 6-311G(d,p) basis 
set. Such DFT calculations are expected to yield an accurate description of van der Waals and 
hydrogen bond interactions [9]. 
Finally the developed FFs from QM calculations in this work are summarized in Table S3. 
 S4 
Table S2. Coordinates (Å) of Zn4O(CO2)6H6 and Zn4O(CO2)6H6-H2 optimized by RI-
MP2/TZVPP. 
Zn-MOF x y z Zn-MOF-H2 x y z 
O 0.004 -0.002 0.006 O 0.008 0.003 0.000 
Zn 0.976 1.119 -1.294 Zn 0.973 1.112 -1.316 
Zn 1.296 -1.087 1.032 Zn 1.308 -1.066 1.027 
Zn -1.014 1.153 1.239 Zn -1.003 1.165 1.233 
Zn -1.238 -1.197 -0.955 Zn -1.240 -1.201 -0.942 
O 1.196 -0.676 2.949 O 1.231 -0.629 2.942 
O 3.135 -0.759 0.426 O 3.144 -0.740 0.412 
O 0.933 -3.006 0.819 O 0.945 -2.988 0.843 
O -0.741 3.053 0.816 O -0.769 3.061 0.769 
O -0.450 0.870 3.10 O -0.431 0.899 3.093 
O -2.941 0.781 1.132 O -2.928 0.781 1.153 
O -1.120 -0.932 -2.897 O -1.141 -0.944 -2.887 
O -0.842 -3.084 -0.583 O -0.829 -3.083 -0.559 
O -3.097 -0.863 -0.416 O -3.095 -0.868 -0.388 
O 0.409 0.720 -3.132 O 0.391 0.700 -3.149 
O 2.913 0.802 -1.197 O 2.908 0.788 -1.242 
O 0.667 3.028 -0.955 O 0.642 3.023 -1.000 
C 0.049 -3.594 0.145 C 0.064 -3.585 0.172 
C -0.416 -0.127 -3.560 C -0.444 -0.144 -3.563 
C -3.565 -0.049 0.421 C -3.557 -0.051 0.450 
C -0.041 3.590 -0.080 C -0.085 3.590 -0.144 
C 3.569 0.020 -0.461 C 3.570 0.024 -0.493 
C 0.439 0.115 3.570 C 0.469 0.158 3.563 
H 0.054 -4.686 0.200 H 0.075 -4.677 0.232 
H -0.538 -0.169 -4.646 H -0.582 -0.187 -4.647 
H -4.651 -0.063 0.547 H -4.643 -0.067 0.584 
H -0.048 4.684 -0.102 H -0.126 4.682 -0.200 
H 4.652 0.019 -0.611 H 4.653 0.024 -0.648 
H 0.570 0.149 4.655 H 0.609 0.203 4.646 
    H 2.328 2.362 1.567 
    H 2.554 1.757 1.9245 
 S5 
Table S3. van der Waals force field parameters developed from QM data in this work. Here H_ 
and H_A indicate hydrogen bonded with aromatic carbon rings such as C6H6 and hydrogen in a 
H2 molecule. 
Term D (kcal/mol) r0 (Å) α 
C---H_A 0.10082 3.12022 12.00625 
H_---H_A 0.00087 3.24722 12.00625 
H_A---H_A a 0.01815 3.56980 10.70940 
O---H_A 0.02515 3.32249 12.00187 
Zn---H_A 0.12447 2.76130 13.41420 
Li---H_A 2.15752 2.01844 7.12510 
a For H_A---H_A vdW term, the potential curves were fitted between two H2 molecules using 
CCSD(T) with aug-cc-pVQZ basis set [9]. 
 
 S6 
S.3 H2 adsorption isotherms of Li-doped MOFs 
To determine the performance of H2 storage capacity designed in this project, we used 
grand canonical Monte Carlo (GCMC) [10]. In these calculations, the structure of the Li-MOF 
system is fixed at the value determined using our FF. Then used the new force field defined 
Table S3 to describe van der Waals interactions of H2 in the MOF systems. To obtain an 
accurate measure of H2 loading, we constructed 10,000,000 configurations to compute the 
average loading for each condition. The sorbent model used a three-dimensional structure 
(2×2×2 supercell) consisting of eight Zn4O(CO2)6 linker units each of which is connected to 6 
organic linkers.  
In all simulations, periodic boundary conditions were applied in order to minimize 
undesirable surface effects. Generally, MOF structures can have both of cubic and hexagonal 
crystals. Experimentally, the hexagonal Zn-MOF177 has a larger surface area based on the 
higher N2 uptake amount than cubic MOF12. However, the hexagonal structure leads to lower 
H2 storage [11]. Thus, we have studied optimization the cubic MOF systems in this work.  
Table S4 lists the crystal sizes and surface areas of the MOFs considered in this study. 
These crystal structures were minimized using the DREIDING force field [12]. The predicted 
structures for Zn-MOF-C6, C10 and C16 are in good agreement with experimental data [13].  
Figure S2 shows the relationship between the Connolly surface area and the H2 BET 
surface area for pure MOFs. The BET surface area is ~ 1/3 the Connolly area, but the 
relationship is ~ linear. 
Using these optimized structures, we calculated H2 adsorption isotherms at 77 and 100 K. 
For Zn-MOF-C6, our predicted H2 adsorption isotherms are compared with experiment [14] in 
Fig. S3, where we find good agreement.  
Figs. S4 and S5 show H2 adsorption isotherms in gravimetric and volumetric units of Li-
doped MOFs at 273 K and pressures <100 bar where the total and excess isotherm data at 273 
and 300 K are indicated in detail in Tables S5-S9.  
In addition, we plot the distribution of H2 in the Li doped MOF-C30 at 243 K and 100 bar 
to meet the DOE target, seen in Fig. S6. The adsorbed H2 are found mainly near Li atoms on 
aromatic carbon atoms. 
 
 S7 
Table S4. Lattice parameters (Å) and surface area (m2/g) of MOFs used in this simulation 
where we assumed that all structures have cubic lattice (Fm-3m space group).  
 MOF6 MOF10 MOF16 MOF22 MOF30 
Lattice 
parameter 
26.025 
(25.832)a 
30.252 
(30.092)a 
34.374 
(34.381)a 
38.652 42.824 
Connolly 
surface areab  
3851c 
(3834)d 
3518c 
(3378)d 
3808c 
(3528)d 
4550c 
(3940)d 
4641c 
(3938)d 
H2 BET 
surface areae 
1287c 
(395)d 
1494c 
(693)d 
1746c 
(920)d 
1955c 
(1040)d 
2046c 
(1138)d 
 
a Experimental results [Ref. 13] 
b The Connolly surface area was calculated by the Cerius2 software. 
c For pure Zn-MOFs 
d For Li-doped Zn-MOFs. Here we assumed that lattice parameters of Li-doped MOFs were 
same to those of pure MOFs. 
e The H2 BET surface area was calculated from our H2 adsorption isotherms at 300 K for Li-
doped MOFs and at 77 K for pure MOFs. 
1200 1400 1600 1800 2000
3400
3600
3800
4000
4200
4400
4600
4800
 
 
C
on
no
lly
 s
ur
fa
ce
 a
re
a 
(m
2 /
g)
H2 BET surface area (m
2/g)
 Y=1.28X+1888.94
                 R=0.81899
MOF-C6
MOF-C10
MOF-C16
MOF-C22
MOF-C30
 
C
on
no
lly
 s
ur
fa
ce
 a
re
a 
(m
2 /
g)
 
 
Figure S2. Comparison of the Connolly surface area and H2 BET surface area for pure MOFs. 
 
 S8 
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
 
 
H 2
 u
pt
ak
e 
am
ou
nt
 (w
t%
)
Pressure (bar)
 MOF-6 (This work)
 MOF-6 (Exp.)
 
Figure S3. Comparison of predicted and experimental [14] data on H2 adsorption of Zn-MOF-
C6 at 77 K. 
 
 S9 
0 20 40 60 80 100
0
1
2
3
4
5
6
 
 
G
ra
vi
m
et
ric
 u
pt
ak
e 
(w
t%
)
Pressure (bar)
 
Figure S4. Predicted excess gravimetric H2 uptake of Li-doped MOFs at 273 K. Here cyan, 
blue, green, red, and black indicate Li-MOF-C6, C10, C16, C22, and C30, respectively. 
 S10 
0 20 40 60 80 100
0
2
4
6
8
10
12
14
16
18
20
 
 
Vo
lu
m
et
ric
 u
pt
ak
e 
(g
/L
)
Pressure (bar)
 
Figure S5. Predicted excess volumetric H2 uptake of Li-doped MOFs at 273 K. Here cyan, blue, 
green, red, and black indicate Li-MOF-C6, C10, C16, C22, and C30, respectively. 
 S11 
Table S5. Simulated H2 adsorption data for Li-MOF-C6 at 273 and 300 K. 
 
Li-MOF-C6 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 1.58 1.51 1.09 1.04 
5 3.64 3.37 2.67 2.41 
10 5.02 4.55 3.79 3.36 
20 6.51 5.76 5.37 4.65 
30 7.47 6.49 6.33 5.41 
40 8.27 7.11 7.10 6.00 
50 8.88 7.54 7.76 6.49 
100 11.12 9.01 10.04 8.03 
a f.u. = Zn4OLx formula unit 
 S12 
Table S6. Simulated H2 adsorption data for Li-MOF-C10 at 273 and 300 K. 
 
Li-MOF-C10 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 4.26 4.17 2.64 2.55 
5 8.91 8.55 6.66 6.32 
10 11.18 10.58 8.97 8.40 
20 13.65 12.69 11.61 10.71 
30 15.16 13.93 13.19 12.03 
40 16.41 14.93 14.40 13.01 
50 17.48 15.76 15.38 13.77 
100 20.86 18.00 19.03 16.35 
a f.u. = Zn4OLx formula unit 
 S13 
Table S7. Simulated H2 adsorption data for Li-MOF-C16 at 273 and 300 K. 
 
Li-MOF-C16 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 8.52 8.32 5.99 5.80 
5 15.51 14.81 12.14 11.49 
10 19.01 17.91 15.83 14.79 
20 22.95 21.21 19.71 18.08 
30 25.45 23.10 22.56 20.35 
40 27.40 24.41 24.35 21.56 
50 29.07 25.45 26.40 23.05 
100 35.21 28.55 32.43 26.24 
a f.u. = Zn4OLx formula unit 
 S14 
Table S8. Simulated H2 adsorption data for Li-MOF-C22 at 273 and 300 K. 
 
Li-MOF-C22 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 12.52 12.23 9.29 9.02 
5 21.46 20.52 17.16 16.28 
10 26.09 24.62 21.61 20.23 
20 30.89 28.44 26.63 24.34 
30 34.31 30.82 30.81 27.57 
40 36.53 32.03 32.35 28.19 
50 38.75 33.23 35.55 30.47 
100 47.92 37.62 44.10 34.50 
a f.u. = Zn4OLx formula unit 
 S15 
Table S9. Simulated H2 adsorption data for Li-MOF-C30 at 273 and 300 K. 
 
Li-MOF-C30 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 22.04 21.66 18.21 17.85 
5 31.91 30.73 27.38 26.27 
10 37.02 35.12 32.56 30.78 
20 43.12 39.77 38.89 35.80 
30 47.46 42.54 42.83 38.35 
40 51.09 44.71 46.76 40.92 
50 54.21 46.35 49.50 42.29 
100 66.87 52.20 61.18 47.68 
a f.u. = Zn4OLx formula unit 
 S16 
 
 
Figure S6. The distribution of adsorbed H2 in Li-doped MOF-C30 at 243 K and 100 bar 
where black, grey, pink, red, and violet colors indicate hydrogen, carbon, lithium, oxygen, 
and zinc atoms, respectively. This leads to 6% wt H2, meeting the DOE goals for 2010 
 
 S17 
S.4. References: 
[1] F. Weigend, M. Häser, Thero. Chem. Acc.97, 331 (1997). 
[2] R. Ahlrichs, M. Bär, M. Häser, H. Horn, C.  Kölmel, Chem. Phys. Lett. 162, 165 
(1989). 
[3] A. Schäfer, C. Huber, R. Ahlrichs, J. Chem. Phys. 100, 5829 (1994). 
[4] T. H. Dunning, T.H.; J. Chem. Phys. 90, 1007 (1989). 
[5] F. Weigend, M. Häser, H. Patzelt, R. Ahlrichs, Chem. Phys. Lett. 294, 143 (1989). 
[6] T. Sagara, J. Klassen, J. Ortony, E. Ganz, J. Chem. Phys. 123, 014701 (2005). 
[7] CRC Handbook. 
[8] W. -Q. Deng, X. Xu, W. A. Goddard III, Phys. Rev. Lett. 92, 166103 (2004). 
[9] X. Xu, W. A. Goddard III, Proc. Natl. Acad. Sci. U.S.A. 101, 2673 (2004). 
[10] Cerius2 software. 
[11] J. L. C. Rowsell, A. R. Millward, K. S. Park, O. M. Yaghi, J. Am. Chem. Soc. 126, 
5666 (2004). 
[12] S. L. Mayo, B. D. Olafson, W. A. Goddard III, J. Phys. Chem. 94, 8897 (1990). 
[13] M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, O. M. Yaghi, 
Science 295, 469 (2002). 
[14] J. L. C. Rowsell, O. M. Yaghi, J. Am. Chem. Soc. 128, 1304 (2006). 
 


Lithium-Doped Metal-Organic Frameworks for Reversible H_2 Storage at Ambient Temperature

 S1 
Supporting Information  
“Li-Doped Metal Organic Frameworks for Reversible H2 Storage at 
Ambient Temperature" 
Sang Soo Han, and William A Goddard III 
Materials and Process Simulation Center, Division of Chemistry and Chemical 
Engineering, California Institute of Technology, Pasadena. CA, 91125 
The supporting material is organized as follows: Section 1 describes quantum mechanics 
calculation details and more results. Section 2 describes the force fields derived from ab-initio 
calculations and section 3 shows H2 adsorption isotherms in gravimetric and volumetric units 
of Li-doped metal organic frameworks (MOFs) at 273 and 300 K. 
S.1. Quantum mechanics calculation of van der Waals interaction parameters 
DFT methods are well known to lead to poor descriptions of the London dispersion 
attractive terms dominating weakly bound van der Waals molecules. Hence, DFT is not useful 
for predicting exact interaction energies between dihydrogen and the organics of MOFs. 
Therefore, we optimized all coupled clusters using the second-order Møller-Plesset (MP2) 
calculations with the approximate resolution of the identity (RI-MP2) [1,2]. These calculations 
were carried out with the TURBOMOLE program [2].  
For H2 on benzene, we used the triple zeta valence basis (TZV) [3] supplemented with 
polarization functions from the cc-pVTZ basis [4], which is denoted as TZVPP (the 1s 
electrons of the C and O atoms are not correlates, frozen-core approximation). The binding 
energy of H2 with benzene was corrected for basis-set superposition error (BSSE) by the full 
counterpoise procedure. In addition, the appropriate auxiliary-TZVPP basis set was used for the 
RI-MP2 calculations [5].  
In the case of H2-MOF clusters, the geometries were optimized up to the RI-MP2/TZVPP 
level of theory with frozen cores in all cases.  Then single point energies were calculated using 
RI-MP2 with the quadruple zeta QZVPP basis. Here we did not use BSSE corrections, since 
this has been shown not to be necessary for Zn-MOF cluster [6].   
The QM calculated H-H bond length, 0.74 Å, is comparable to the experimental value of 
0.75 Å for free H2 molecule [7]. Moreover, the QM vibration frequency of H2 is 4224 cm-1, 
which is close to the experimental value of 4400 cm-1 for free H2 [7]. We calculate the H2 
binding energy with the Zn containing cluster to be -1.49 kcal/mol (Table S1), in good 
agreement with the result of -1.51 kcal/mol from Ref. [6]. 
 S2 
Table S1. QM data (RI-MP2, energies in Hartree) and force field data (energies in kcal/mol) for 
binding of an H2 molecule to the metal oxide cluster and to the benzene ring.  
 Zn cluster- H2 a Benzene- H2 b 
H2 -1.166651 -1.164698 
M4O(CO2)6H6 -8322.821264 -231.733624 
M4O(CO2)6H6-H2 -8323.990283 -232.899789 
Binding energy -1.49 -0.91 
Force field -1.48 -0.91 
aQZVPP basis set 
bTZVPP basis set 
 S3 
 S.2 Fitting of the Force Field  
We used QM calculations to determine interaction potential of H2 with the metal 
sites and organic linkers of the MOF with different. Then we fitted these results to obtain 
Morse pair potentials (Eq. (1)) between each atom of H with the MOF 
 
⎪⎭
⎪
⎬
⎫
⎪⎩
⎪
⎨
⎧
−⋅−−= )]1(
2
exp[2)]1(exp[)(
or
ijr
or
ijrDijrUij
αα
            (1) 
Here the parameters D is the well depth, r0 is the equilibrium bond distance, and α determines 
the stiffness (force constant).  
For the C-H cross term, we carried out RI-MP2/TZVPP calculations for the interaction between 
H2 and C6H6 molecules as shown in Fig. S1.  
  
Figure S1. Comparison of the quantum calculations and fitted force fields for H2 interacting 
with C6H6. In these calculations, the H2 was oriented vertically to the C6H6 ring and the 
distance between the bond midpoint of H2 and the center of the benzene were varied.  
 
For the interactions of H2 with the metal site in MOF, we carried RI-MP2/QZVPP calculations 
for clusters such as Zn4O(CO2)6H6+H2 in Table S1. And the optimized structures are indicated 
in Table S2. 
To determine the interactions of H2 with the Li bonded to an aromatic hydrocarbon we 
considered one H2 bonded to a planar C32 cluster (ten aromatic rings) doped with one Li atom 
on each side [8]. These calculations used the X3LYP flavor of DFT with the 6-311G(d,p) basis 
set. Such DFT calculations are expected to yield an accurate description of van der Waals and 
hydrogen bond interactions [9]. 
Finally the developed FFs from QM calculations in this work are summarized in Table S3. 
 S4 
Table S2. Coordinates (Å) of Zn4O(CO2)6H6 and Zn4O(CO2)6H6-H2 optimized by RI-
MP2/TZVPP. 
Zn-MOF x y z Zn-MOF-H2 x y z 
O 0.004 -0.002 0.006 O 0.008 0.003 0.000 
Zn 0.976 1.119 -1.294 Zn 0.973 1.112 -1.316 
Zn 1.296 -1.087 1.032 Zn 1.308 -1.066 1.027 
Zn -1.014 1.153 1.239 Zn -1.003 1.165 1.233 
Zn -1.238 -1.197 -0.955 Zn -1.240 -1.201 -0.942 
O 1.196 -0.676 2.949 O 1.231 -0.629 2.942 
O 3.135 -0.759 0.426 O 3.144 -0.740 0.412 
O 0.933 -3.006 0.819 O 0.945 -2.988 0.843 
O -0.741 3.053 0.816 O -0.769 3.061 0.769 
O -0.450 0.870 3.10 O -0.431 0.899 3.093 
O -2.941 0.781 1.132 O -2.928 0.781 1.153 
O -1.120 -0.932 -2.897 O -1.141 -0.944 -2.887 
O -0.842 -3.084 -0.583 O -0.829 -3.083 -0.559 
O -3.097 -0.863 -0.416 O -3.095 -0.868 -0.388 
O 0.409 0.720 -3.132 O 0.391 0.700 -3.149 
O 2.913 0.802 -1.197 O 2.908 0.788 -1.242 
O 0.667 3.028 -0.955 O 0.642 3.023 -1.000 
C 0.049 -3.594 0.145 C 0.064 -3.585 0.172 
C -0.416 -0.127 -3.560 C -0.444 -0.144 -3.563 
C -3.565 -0.049 0.421 C -3.557 -0.051 0.450 
C -0.041 3.590 -0.080 C -0.085 3.590 -0.144 
C 3.569 0.020 -0.461 C 3.570 0.024 -0.493 
C 0.439 0.115 3.570 C 0.469 0.158 3.563 
H 0.054 -4.686 0.200 H 0.075 -4.677 0.232 
H -0.538 -0.169 -4.646 H -0.582 -0.187 -4.647 
H -4.651 -0.063 0.547 H -4.643 -0.067 0.584 
H -0.048 4.684 -0.102 H -0.126 4.682 -0.200 
H 4.652 0.019 -0.611 H 4.653 0.024 -0.648 
H 0.570 0.149 4.655 H 0.609 0.203 4.646 
    H 2.328 2.362 1.567 
    H 2.554 1.757 1.9245 
 S5 
Table S3. van der Waals force field parameters developed from QM data in this work. Here H_ 
and H_A indicate hydrogen bonded with aromatic carbon rings such as C6H6 and hydrogen in a 
H2 molecule. 
Term D (kcal/mol) r0 (Å) α 
C---H_A 0.10082 3.12022 12.00625 
H_---H_A 0.00087 3.24722 12.00625 
H_A---H_A a 0.01815 3.56980 10.70940 
O---H_A 0.02515 3.32249 12.00187 
Zn---H_A 0.12447 2.76130 13.41420 
Li---H_A 2.15752 2.01844 7.12510 
a For H_A---H_A vdW term, the potential curves were fitted between two H2 molecules using 
CCSD(T) with aug-cc-pVQZ basis set [9]. 
 
 S6 
S.3 H2 adsorption isotherms of Li-doped MOFs 
To determine the performance of H2 storage capacity designed in this project, we used 
grand canonical Monte Carlo (GCMC) [10]. In these calculations, the structure of the Li-MOF 
system is fixed at the value determined using our FF. Then used the new force field defined 
Table S3 to describe van der Waals interactions of H2 in the MOF systems. To obtain an 
accurate measure of H2 loading, we constructed 10,000,000 configurations to compute the 
average loading for each condition. The sorbent model used a three-dimensional structure 
(2×2×2 supercell) consisting of eight Zn4O(CO2)6 linker units each of which is connected to 6 
organic linkers.  
In all simulations, periodic boundary conditions were applied in order to minimize 
undesirable surface effects. Generally, MOF structures can have both of cubic and hexagonal 
crystals. Experimentally, the hexagonal Zn-MOF177 has a larger surface area based on the 
higher N2 uptake amount than cubic MOF12. However, the hexagonal structure leads to lower 
H2 storage [11]. Thus, we have studied optimization the cubic MOF systems in this work.  
Table S4 lists the crystal sizes and surface areas of the MOFs considered in this study. 
These crystal structures were minimized using the DREIDING force field [12]. The predicted 
structures for Zn-MOF-C6, C10 and C16 are in good agreement with experimental data [13].  
Figure S2 shows the relationship between the Connolly surface area and the H2 BET 
surface area for pure MOFs. The BET surface area is ~ 1/3 the Connolly area, but the 
relationship is ~ linear. 
Using these optimized structures, we calculated H2 adsorption isotherms at 77 and 100 K. 
For Zn-MOF-C6, our predicted H2 adsorption isotherms are compared with experiment [14] in 
Fig. S3, where we find good agreement.  
Figs. S4 and S5 show H2 adsorption isotherms in gravimetric and volumetric units of Li-
doped MOFs at 273 K and pressures <100 bar where the total and excess isotherm data at 273 
and 300 K are indicated in detail in Tables S5-S9.  
In addition, we plot the distribution of H2 in the Li doped MOF-C30 at 243 K and 100 bar 
to meet the DOE target, seen in Fig. S6. The adsorbed H2 are found mainly near Li atoms on 
aromatic carbon atoms. 
 
 S7 
Table S4. Lattice parameters (Å) and surface area (m2/g) of MOFs used in this simulation 
where we assumed that all structures have cubic lattice (Fm-3m space group).  
 MOF6 MOF10 MOF16 MOF22 MOF30 
Lattice 
parameter 
26.025 
(25.832)a 
30.252 
(30.092)a 
34.374 
(34.381)a 
38.652 42.824 
Connolly 
surface areab  
3851c 
(3834)d 
3518c 
(3378)d 
3808c 
(3528)d 
4550c 
(3940)d 
4641c 
(3938)d 
H2 BET 
surface areae 
1287c 
(395)d 
1494c 
(693)d 
1746c 
(920)d 
1955c 
(1040)d 
2046c 
(1138)d 
 
a Experimental results [Ref. 13] 
b The Connolly surface area was calculated by the Cerius2 software. 
c For pure Zn-MOFs 
d For Li-doped Zn-MOFs. Here we assumed that lattice parameters of Li-doped MOFs were 
same to those of pure MOFs. 
e The H2 BET surface area was calculated from our H2 adsorption isotherms at 300 K for Li-
doped MOFs and at 77 K for pure MOFs. 
1200 1400 1600 1800 2000
3400
3600
3800
4000
4200
4400
4600
4800
 
 
C
on
no
lly
 s
ur
fa
ce
 a
re
a 
(m
2 /
g)
H2 BET surface area (m
2/g)
 Y=1.28X+1888.94
                 R=0.81899
MOF-C6
MOF-C10
MOF-C16
MOF-C22
MOF-C30
 
C
on
no
lly
 s
ur
fa
ce
 a
re
a 
(m
2 /
g)
 
 
Figure S2. Comparison of the Connolly surface area and H2 BET surface area for pure MOFs. 
 
 S8 
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
 
 
H 2
 u
pt
ak
e 
am
ou
nt
 (w
t%
)
Pressure (bar)
 MOF-6 (This work)
 MOF-6 (Exp.)
 
Figure S3. Comparison of predicted and experimental [14] data on H2 adsorption of Zn-MOF-
C6 at 77 K. 
 
 S9 
0 20 40 60 80 100
0
1
2
3
4
5
6
 
 
G
ra
vi
m
et
ric
 u
pt
ak
e 
(w
t%
)
Pressure (bar)
 
Figure S4. Predicted excess gravimetric H2 uptake of Li-doped MOFs at 273 K. Here cyan, 
blue, green, red, and black indicate Li-MOF-C6, C10, C16, C22, and C30, respectively. 
 S10 
0 20 40 60 80 100
0
2
4
6
8
10
12
14
16
18
20
 
 
Vo
lu
m
et
ric
 u
pt
ak
e 
(g
/L
)
Pressure (bar)
 
Figure S5. Predicted excess volumetric H2 uptake of Li-doped MOFs at 273 K. Here cyan, blue, 
green, red, and black indicate Li-MOF-C6, C10, C16, C22, and C30, respectively. 
 S11 
Table S5. Simulated H2 adsorption data for Li-MOF-C6 at 273 and 300 K. 
 
Li-MOF-C6 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 1.58 1.51 1.09 1.04 
5 3.64 3.37 2.67 2.41 
10 5.02 4.55 3.79 3.36 
20 6.51 5.76 5.37 4.65 
30 7.47 6.49 6.33 5.41 
40 8.27 7.11 7.10 6.00 
50 8.88 7.54 7.76 6.49 
100 11.12 9.01 10.04 8.03 
a f.u. = Zn4OLx formula unit 
 S12 
Table S6. Simulated H2 adsorption data for Li-MOF-C10 at 273 and 300 K. 
 
Li-MOF-C10 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 4.26 4.17 2.64 2.55 
5 8.91 8.55 6.66 6.32 
10 11.18 10.58 8.97 8.40 
20 13.65 12.69 11.61 10.71 
30 15.16 13.93 13.19 12.03 
40 16.41 14.93 14.40 13.01 
50 17.48 15.76 15.38 13.77 
100 20.86 18.00 19.03 16.35 
a f.u. = Zn4OLx formula unit 
 S13 
Table S7. Simulated H2 adsorption data for Li-MOF-C16 at 273 and 300 K. 
 
Li-MOF-C16 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 8.52 8.32 5.99 5.80 
5 15.51 14.81 12.14 11.49 
10 19.01 17.91 15.83 14.79 
20 22.95 21.21 19.71 18.08 
30 25.45 23.10 22.56 20.35 
40 27.40 24.41 24.35 21.56 
50 29.07 25.45 26.40 23.05 
100 35.21 28.55 32.43 26.24 
a f.u. = Zn4OLx formula unit 
 S14 
Table S8. Simulated H2 adsorption data for Li-MOF-C22 at 273 and 300 K. 
 
Li-MOF-C22 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 12.52 12.23 9.29 9.02 
5 21.46 20.52 17.16 16.28 
10 26.09 24.62 21.61 20.23 
20 30.89 28.44 26.63 24.34 
30 34.31 30.82 30.81 27.57 
40 36.53 32.03 32.35 28.19 
50 38.75 33.23 35.55 30.47 
100 47.92 37.62 44.10 34.50 
a f.u. = Zn4OLx formula unit 
 S15 
Table S9. Simulated H2 adsorption data for Li-MOF-C30 at 273 and 300 K. 
 
Li-MOF-C30 
 273 K 300 K 
Pressure 
(bar) 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
Total H2 per 
f.u.a 
Excess H2 per 
f.u.a 
1 22.04 21.66 18.21 17.85 
5 31.91 30.73 27.38 26.27 
10 37.02 35.12 32.56 30.78 
20 43.12 39.77 38.89 35.80 
30 47.46 42.54 42.83 38.35 
40 51.09 44.71 46.76 40.92 
50 54.21 46.35 49.50 42.29 
100 66.87 52.20 61.18 47.68 
a f.u. = Zn4OLx formula unit 
 S16 
 
 
Figure S6. The distribution of adsorbed H2 in Li-doped MOF-C30 at 243 K and 100 bar 
where black, grey, pink, red, and violet colors indicate hydrogen, carbon, lithium, oxygen, 
and zinc atoms, respectively. This leads to 6% wt H2, meeting the DOE goals for 2010 
 
 S17 
S.4. References: 
[1] F. Weigend, M. Häser, Thero. Chem. Acc.97, 331 (1997). 
[2] R. Ahlrichs, M. Bär, M. Häser, H. Horn, C.  Kölmel, Chem. Phys. Lett. 162, 165 
(1989). 
[3] A. Schäfer, C. Huber, R. Ahlrichs, J. Chem. Phys. 100, 5829 (1994). 
[4] T. H. Dunning, T.H.; J. Chem. Phys. 90, 1007 (1989). 
[5] F. Weigend, M. Häser, H. Patzelt, R. Ahlrichs, Chem. Phys. Lett. 294, 143 (1989). 
[6] T. Sagara, J. Klassen, J. Ortony, E. Ganz, J. Chem. Phys. 123, 014701 (2005). 
[7] CRC Handbook. 
[8] W. -Q. Deng, X. Xu, W. A. Goddard III, Phys. Rev. Lett. 92, 166103 (2004). 
[9] X. Xu, W. A. Goddard III, Proc. Natl. Acad. Sci. U.S.A. 101, 2673 (2004). 
[10] Cerius2 software. 
[11] J. L. C. Rowsell, A. R. Millward, K. S. Park, O. M. Yaghi, J. Am. Chem. Soc. 126, 
5666 (2004). 
[12] S. L. Mayo, B. D. Olafson, W. A. Goddard III, J. Phys. Chem. 94, 8897 (1990). 
[13] M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, O. M. Yaghi, 
Science 295, 469 (2002). 
[14] J. L. C. Rowsell, O. M. Yaghi, J. Am. Chem. Soc. 128, 1304 (2006). 
 


English

https://authors.library.caltech.edu/76850/2/ja072599%2Bsi20070529_070553.pdf

Lithium-Doped Metal-Organic Frameworks for Reversible H_2 Storage at Ambient Temperature

Abstract

Similar works

Full text

Available Versions

Caltech Authors - Main

Caltech Authors - Main