We report the H_2 uptake properties of six covalent organic frameworks (COFs) from first-principles-based grand canonical Monte-Carlo simulations. The predicted H_2 adsorption isotherm is in excellent agreement with the only available experimental result (3.3 vs 3.4 wt % at 50 bar and 77 K for COF-5), also reported here, validating the predictions. We predict that COF-105 and COF-108 lead to a reversible excess H_2 uptake of 10.0 wt % at 77 K, making them the best known storage materials for molecular hydrogen at 77 K. We predict that the total H_2 uptake for COF-108 is 18.9 wt % at 77 K. COF-102 shows the best volumetric performance, storing 40.4 g/L of H_2 at 77 K. These results indicate that the COF systems are most promising candidates for practical hydrogen storage

Furukawa, Hiroyasu

Goddard, William A., III

Han, Sang Soo

Yaghi, Omar M.

Caltech Authors - Main

 -S1- 
 
Supporting Information (14 pages)  
 
 
 
 
Covalent Organic Frameworks as Exceptional Hydrogen Storage 
Materials 
 
Sang Soo Han,† Hiroyasu Furukawa,‡ Omar M. Yaghi,*,‡ and William A Goddard III*,† 
 
† Materials and Process Simulation Center, Department of Chemistry, California Institute of 
Technology, Pasadena, CA 91125 
‡ Center for Reticular Chemistry, Department of Chemistry and Biochemistry, University of 
California, Los Angeles, CA 90095 
* To whom correspondence should be addressed. 
E-mail: yaghi@chem.ucla.edu, wag@wag.caltech.edu 
 
 
 
 
Quantum mechanics calculation  
of van der Waals interaction parameters     S2 
Fitting of the Force Field (FF)      S2 
Simulation of H2 adsorption isotherms for COFs     S4 
Sample preparation and high-pressure H2 isotherm for COF-5  S5 
References        S14
 -S2- 
 
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 covalent organic frameworks (COFs) where the 
building blocks are linked by strong covalent bonds such as C-C, C-O, B-O, and Si-C. 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 boroxine (B3O3H3) and silane (SiH4), we used the quadruple zeta valence basis 
(QZV) [3] supplemented with polarization functions from the cc-pVTZ basis [4], which is denoted 
as QZVPP. The binding energy of H2 with the boroxine and silane was corrected for basis-set 
superposition error (BSSE) by the full counterpoise procedure. In addition, the appropriate 
auxiliary-QZVPP basis set was used for the RI-MP2 calculations [5].  
 
S.2  Fitting of the Force Field (FF) 
We used QM calculations to determine interaction potential of H2 with organic linkers of the 
COF. Then we fitted these results to obtain Morse pair potentials (Eq. (1)) between each atom of 
H with the COF 
 
⎪⎭
⎪⎬
⎫
⎪⎩
⎪⎨
⎧
−⋅−−= )]1(
2
exp[2)]1(exp[)(
or
ijr
or
ijrDijrUij
αα
            (1) 
Here the parameter D is the well depth, r0 is the equilibrium bond distance, and α determines the 
stiffness (force constant).  
For the B-H and Si-H cross terms, we carried out RI-MP2/QZVPP calculations for the 
interaction between H2 and boroxine molecule and between H2 and silane as shown in Fig. S1. 
Other terms such as C-H were already developed and published in Ref. 6 and 7. Moreover all FFs 
used in this work from QM calculations are summarized in Table S1. 
 -S3- 
 
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
En
er
gy
 (k
ca
l/m
ol
)
d (Ang.)
 FF
 RI-MP2
d
B
OH
En
er
gy
 (k
ca
l/m
ol
)
En
er
gy
 (k
ca
l/m
ol
)
2.5 3.0 3.5 4.0 4.5 5.0 5.5
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
E
ne
rg
y 
(k
ca
l/m
ol
)
d (Ang.)
 FF
 RI-MP2
d
H Si
E
ne
rg
y 
(k
ca
l/m
ol
)
E
ne
rg
y 
(k
ca
l/m
ol
)
 
Figure S1. Comparison of the quantum calculations and fitted force fields for H2 interacting with 
boroxine (B3O3H3) (left) and silane (SiH4). In these calculations, the H2 was oriented parallel to the 
B3O3H3 ring and the distance between the bond midpoint of H2 and the center of the boroxine and 
silane were varied.  
 
Table S1. 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 
B---H_A 0.04825 3.49300 10.56518 
Si---H_A 0.11014 3.53350 14.16509 
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 [8]. 
 
 -S4- 
 
S.3  Simulation of H2 adsorption isotherms for COFs 
To determine the performance of H2 storage capacity designed in this work, we used grand 
canonical Monte Carlo (GCMC). During these calculations, the structure of the COF system is 
fixed at the value determined using our FF. Then used the new force field defined Table S1 to 
describe van der Waals interactions of H2 in the COF systems. To obtain an accurate measure of H2 
loading, we constructed 10,000,000 configurations to compute the average loading for each 
condition. For the simulation, we used experimental COF structures [9,10]. The sorbent model is 
an infinite three-dimensional periodic super cell, 2×2×3 for COF-1, 2×2×6 for COF-5, and 2×2×2 
for COF-102, 103, 105, and 108 of each unit cell to eliminate boundary effects. Here both 
supercells for two-dimensional COFs, COF-1 and COF-5 have six layers. 
Also through the GCMC simulation, we investigated H2 adsorption sites in COFs at 77 K. 
Figure S2 shows snapshots of structures of COF-108 with adsorbed H2 at two pressures, 0.1 and 80 
bar. At 0.1 bar, one can find that the most favored adsorption site of H2 is on benzene rings in the 
organic linkers. In addition at 80 bar, most H2 is adsorbed on the benzene rings as well as some H2 
can occupy near boron-oxygen networks. For other COFs, the similar behavior is observed. From 
this fact the most important adsorption site in COFs is the benzene ring.  
 
 -S5- 
 
S.4  Sample preparation and high-pressure H2 isotherm for COF-5 
Sample preparation. Crystalline sample of the as-synthesized COF-5 was obtained using 
already published procedure [9]. Briefly, 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and 1,4-
benzenediboronic acid (BDBA) were purchased from TCI and Aldrich, respectively. Mesitylene 
(98%, Fluka) and anhydrous 1,2-dioxane (99.8%, Aldrich) were used for the condensation 
reactions. Typically, the reaction mixture (i.e. boronic acid and HHTP in mesitylene/dioxane (1:1, 
v/v)) was heated at 100 °C for 72 h to afford powder precipitates. The resulting powder was filtered 
off and was washed with dry acetone (3 ×). The powder was then activated with acetone (2 ×) for 2 
days then dried at 85 °C/10-5 torr for 12 h to afford COF-5. The identity was confirmed using 
elemental microanalysis, thermal gravimetric analysis, FT-IR spectroscopy, and powder X-ray 
diffraction.  
Gravimetric high-pressure gas adsorption measurements. Gravimetric gas sorption isotherms 
were measured by use of GHP-300 (Gravimetric High Pressure analyzer) from the VTI 
Corporation [11]. A Rubotherm magnetic suspension balance MC-5 was used to measure the 
change in mass of samples suspended within a tube (22 mm i.d.) constructed from Inconel 625 
under a chosen atmosphere. Prior to admittance of the analyte gas, the entire chamber and manifold 
were evacuated at room temperature, and the weight of Al sample bucket (12 mm i.d. × 21 mm 
length) was measured. After loading COF samples (200-400 mg) the system was purged at room 
temperature with helium, and the sample was outgassed, using a turbomolecular drag pump 
(Pfeiffer, TSH 071 E), until a constant mass was attained. Ultra-high purity grade He and H2 
(99.999% purity) were used throughout the adsorption experiments. When H2 gas was used, water 
and other condensable impurities were removed with a liquid nitrogen trap. Pressure was measured 
with a MKS Baratron transducer 120AA (0 to 1000 Torr) and an electronic Bourdon gauge-type 
transducer (Mensor, up to 1500 psi). The adsorbate was added incrementally, and data points were 
recorded when no further change in mass was observed. The temperature in the Inconel tube was 
also monitored with a platinum resistance thermometer.  
To obtain the excess adsorption isotherm, all data points were corrected for buoyancy and the 
thermal gradient that arises between the balance (313 K) and the sample bucket. Buoyancy and 
 -S6- 
 
thermal-gradient effects exhibited by the bucket and the components associated with the magnetic-
suspension balance were corrected on the basis of the change in mass of the empty bucket within 
the analyte gas at experimental temperature. The weight loss due to the buoyancy of the adsorbent 
was determined by multiplying the volume of COF framework skeleton (i.e. backbone density, dbb) 
times the density of H2 (i.e. corrected mass for buoyancy is Vbb × ρbulk). The volume of COF 
framework skeleton was determined from the helium (< 15 bar) buoyancy curve at 298 K using the 
same gravimetric system [11]. 
 
 
 -S7- 
 
Table S2. Simulated H2 adsorption amount and isosteric heat of adsorption (Qst) for pure COF-1 at 
77 K. 
 
COF-1 
 Gravimetric unit (wt%) Volumetric unit (g/L) 
Pressure 
(bar) 
Total Excess Total Excess 
 
Qst 
(kJ/mol) 
0.1 1.72 1.72 15.89 15.88 8.81 
0.2 1.94 1.94 17.98 17.98 8.52 
0.3 2.11 2.11 19.59 19.59 8.29 
0.4 2.23 2.23 20.75 20.74 8.13 
0.5 2.34 2.33 21.74 21.74 8.04 
0.6 2.42 2.42 22.53 22.53 7.98 
0.7 2.49 2.49 23.23 23.23 7.90 
0.8 2.53 2.53 23.65 23.64 7.85 
0.9 2.59 2.59 24.19 24.18 7.80 
1 2.62 2.62 24.49 24.49 7.76 
5 3.21 3.20 30.12 30.09 7.40 
10 3.38 3.37 31.77 31.73 7.29 
20 3.54 3.53 33.34 33.26 7.23 
30 3.62 3.61 34.14 34.04 7.16 
40 3.64 3.63 34.35 34.22 7.15 
50 3.71 3.69 35.02 34.87 7.12 
60 3.72 3.70 35.09 34.92 7.09 
70 3.77 3.75 35.62 35.43 7.07 
80 3.77 3.75 35.64 35.44 7.06 
90 3.81 3.78 35.97 35.75 7.05 
100 3.82 3.79 36.08 35.84 7.03 
 -S8- 
 
Table S3. Simulated H2 adsorption amount and isosteric heat of adsorption (Qst) for pure COF-5 at 
77 K. 
 
COF-5 
 Gravimetric unit (wt%) Volumetric unit (g/L)
Pressure 
(bar) 
Total Excess Total Excess 
 
Qst (kJ/mol) 
0.1 0.08 0.08 0.48 0.45 4.60 
0.2 0.16 0.15 0.93 0.88 4.59 
0.3 0.24 0.23 1.42 1.35 4.63 
0.4 0.30 0.29 1.77 1.69 4.62 
0.5 0.37 0.35 2.15 2.06 4.61 
0.6 0.44 0.43 2.59 2.49 4.58 
0.7 0.49 0.47 2.87 2.75 4.57 
0.8 0.53 0.51 3.09 2.96 4.54 
0.9 0.61 0.58 3.55 3.41 4.56 
1 0.66 0.63 3.85 3.69 4.56 
5 1.81 1.68 10.71 9.93 4.34 
10 2.46 2.21 14.67 13.13 4.15 
20 3.23 2.73 19.42 16.32 3.90 
30 3.73 3.00 22.54 17.98 3.73 
40 4.12 3.14 24.96 18.86 3.59 
50 4.43 3.24 26.96 19.47 3.50 
60 4.68 3.28 28.56 19.73 3.41 
70 4.92 3.33 30.10 20.03 3.35 
80 5.16 3.39 31.61 20.39 3.30 
90 5.35 3.40 32.83 20.46 3.27 
100 5.50 3.40 33.81 20.49 3.23 
 
 -S9- 
 
Table S4. Simulated H2 adsorption amount and isosteric heat of adsorption (Qst) for pure COF-102 
at 77 K. 
 
COF-102 
 Gravimetric unit (wt%) Volumetric unit (g/L)
Pressure 
(bar) 
Total Excess Total Excess 
 
Qst (kJ/mol) 
0.1 0.52 0.51 2.18 2.15 5.68 
0.2 0.93 0.92 3.96 3.90 5.64 
0.3 1.30 1.28 5.55 5.47 5.64 
0.4 1.54 1.52 6.60 6.50 5.59 
0.5 1.84 1.81 7.88 7.76 5.58 
0.6 2.04 2.01 8.76 8.63 5.56 
0.7 2.26 2.23 9.71 9.57 5.55 
0.8 2.40 2.37 10.36 10.20 5.49 
0.9 2.58 2.55 11.16 10.99 5.47 
1 2.71 2.67 11.70 11.53 5.46 
5 5.30 5.17 23.54 22.93 5.00 
10 6.59 6.34 29.66 28.49 4.72 
20 7.96 7.49 36.38 34.07 4.52 
30 8.76 8.08 40.37 36.95 4.44 
40 9.28 8.40 43.01 38.59 4.38 
50 9.60 8.53 44.65 39.20 4.32 
60 9.93 8.69 46.37 40.01 4.26 
70 10.10 8.68 47.28 39.98 4.28 
80 10.34 8.77 48.56 40.43 4.25 
90 10.51 8.77 49.39 40.43 4.23 
100 10.60 8.70 49.89 40.06 4.22 
 
 -S10- 
 
Table S5. Simulated H2 adsorption amount and isosteric heat of adsorption (Qst) for pure COF-103 
at 77 K. 
 
COF-103 
 Gravimetric unit (wt%) Volumetric unit (g/L)
Pressure 
(bar) 
Total Excess Total Excess 
 
Qst (kJ/mol) 
0.1 0.59 0.58 2.31 2.28 5.78 
0.2 1.00 0.99 3.95 3.88 5.74 
0.3 1.41 1.39 5.56 5.48 5.74 
0.4 1.72 1.69 6.80 6.70 5.69 
0.5 1.98 1.95 7.85 7.74 5.68 
0.6 2.14 2.11 8.52 8.39 5.64 
0.7 2.38 2.34 9.47 9.33 5.64 
0.8 2.56 2.52 10.22 10.07 5.60 
0.9 2.65 2.61 10.59 10.42 5.55 
1 2.84 2.80 11.37 11.19 5.57 
5 5.40 5.25 22.19 21.54 4.97 
10 6.84 6.55 28.55 27.26 4.70 
20 8.32 7.77 35.27 32.74 4.45 
30 9.13 8.33 39.07 35.32 4.35 
40 9.71 8.67 41.79 36.92 4.28 
50 10.15 8.90 43.95 37.98 4.22 
60 10.48 9.02 45.50 38.44 4.19 
70 10.70 9.03 46.61 38.53 4.18 
80 10.93 9.04 47.70 38.60 4.15 
90 11.10 9.10 48.52 38.65 4.10 
100 11.34 8.70 49.72 38.91 4.10 
 
 -S11- 
 
Table S6. Simulated H2 adsorption amount and isosteric heat of adsorption (Qst) for pure COF-105 
at 77 K. 
 
COF-105 
 Gravimetric unit (wt%) Volumetric unit (g/L)
Pressure 
(bar) 
Total Excess Total Excess 
 
Qst (kJ/mol) 
0.1 0.60 0.58 1.07 1.03 5.64 
0.2 1.02 0.98 1.81 1.75 5.56 
0.3 1.36 1.31 2.42 2.35 5.51 
0.4 1.65 1.60 2.95 2.86 5.48 
0.5 1.86 1.80 3.35 3.23 5.42 
0.6 2.08 2.00 3.74 3.60 5.38 
0.7 2.29 2.21 4.14 3.98 5.35 
0.8 2.47 2.37 4.46 4.28 5.31 
0.9 2.60 2.49 4.71 4.50 5.27 
1 2.76 2.64 5.00 4.77 5.23 
5 5.51 4.94 10.29 9.16 4.42 
10 7.36 6.25 14.00 11.75 3.99 
20 9.88 7.75 19.33 14.81 3.49 
30 11.79 8.66 23.56 16.72 3.26 
40 13.18 9.12 26.76 17.70 3.07 
50 14.35 9.45 29.53 18.40 2.95 
60 15.41 9.69 32.13 18.91 2.85 
70 16.33 9.85 34.42 19.26 2.80 
80 17.13 9.98 36.44 19.54 2.75 
90 17.75 9.97 38.04 19.53 2.72 
100 18.31 9.93 39.51 19.43 2.69 
 
 -S12- 
 
Table S7. Simulated H2 adsorption amount and isosteric heat of adsorption (Qst) for pure COF-108 
at 77 K. 
 
COF-108 
 Gravimetric unit (wt%) Volumetric unit (g/L)
Pressure 
(bar) 
Total Excess Total Excess 
 
Qst (kJ/mol) 
0.1 0.93 0.90 1.60 1.54 7.39 
0.2 1.30 1.25 2.25 2.16 6.92 
0.3 1.58 1.51 2.73 2.61 6.63 
0.4 1.83 1.75 3.17 3.03 6.39 
0.5 2.00 1.91 3.48 3.31 6.27 
0.6 2.14 2.03 3.72 3.54 6.14 
0.7 2.32 2.20 4.05 3.84 5.99 
0.8 2.46 2.33 4.29 4.06 5.92 
0.9 2.58 2.46 4.52 4.27 5.86 
1 2.72 2.57 4.76 4.49 5.78 
5 5.38 4.76 9.70 8.53 4.59 
10 7.32 6.12 13.46 11.12 4.07 
20 9.95 7.66 18.84 14.15 3.56 
30 11.80 8.45 22.81 15.74 3.29 
40 13.40 9.12 26.37 17.10 3.12 
50 14.68 9.45 29.33 17.79 2.99 
60 15.75 9.64 31.88 18.20 2.90 
70 16.65 9.76 34.06 18.44 2.82 
80 17.46 9.84 36.07 18.61 2.77 
90 18.17 9.88 37.85 18.69 2.73 
100 18.95 10.01 39.86 18.98 2.73 
 
 -S13- 
 
 
 
 
(a) 
 
 
(b) 
 
 
Figure S2. GCMC snapshots of the structures of COF-108 with adsorbed H2 at two pressures, (a) 
0.1 bar and (b) 80 bar. The atoms are colored as follows: gray = C, red = O, pink = B, white and 
yellow = H where the adsorbed H2 is shown as yellow atoms. 
 -S14- 
 
S.5  References 
[1] F. Weigend, M. Häser, Thero. Chem. Acc., 1997, 97, 331. 
[2] R. Ahlrichs, M. Bär, M. Häser, H. Horn, C. Kölmel, Chem. Phys. Lett., 1989, 162, 165. 
[3] A. Schäfer, C. Huber, R. Ahlrichs, J. Chem. Phys., 1994, 100, 5829. 
[4] T. H. Dunning, J. Chem. Phys., 1989, 90, 1007. 
[5] F. Weigend, M. Häser, H. Patzelt, R. Ahlrichs, Chem. Phys. Lett., 1989, 294, 143. 
[6] S. S. Han, W. Q. Deng, W. A. Goddard, Angew. Chem. Int. Ed., 2007, 46, 6289. 
[7] S. S. Han, W. A. Goddard, J. Am. Chem. Soc., 2007, 129, 8422. 
[8] W. Q. Deng, X. Xu, W. A. Goddard, Phys. Rev. Lett., 2004, 92, 166103. 
[9] A. P. Côté, A. I. Benin, N. W. Ockwig, M. O’Keeffe, A. J. Matzger, O. M. Yaghi, Science, 
2005, 310, 1166. 
[10] H. M. El-Kaderi, J. R. Hunt, J. L. Mendoza-Cortés, A. P. Côté, R. E. Taylor, M. O’Keeffe, 
O. M. Yaghi, Science, 2007, 316, 268. 
[11] H. Furukawa, M. A. Miller, O. M. Yaghi, J. Mater. Chem., 2007, 17, 3197. 
 
 


Covalent Organic Frameworks as Exceptional Hydrogen Storage Materials

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Covalent Organic Frameworks as Exceptional Hydrogen Storage Materials

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