Project ID #BES008

Peter Pfeifer,1 Carlos Wexler,1 Jacob Burress,1 Mark W. Lee,2 M. Frederick Hawthorne,1,2,3,4 Satish Jalisatgi3,4

Departments of 1Physics, 2Chemistry, & 3Radiology 4International Institute of Nano and Molecular Medicine

University of Missouri, Columbia, MO 65211 http://all-craft.missouri.edu

2012 DOE Hydrogen Program Annual Merit Review, May 14-18, 2012

This presentation does not contain any proprietary, confidential, or otherwise restricted information

1

New Pathways and Metrics for Enhanced, Reversible Hydrogen Storage in Boron-

Doped Carbon Nanospaces

Research Team University of Missouri, Physics Peter Pfeifer

Carlos Wexler

Ping Yu

Jacob Burress

Raina Olsen

Lucyna Firlej (Université Montpellier 2)

Bogdan Kuchta (Université Aix-Marseille)

Students, Physics Matt Beckner - Matt Connolly -

Elmar Dohnke - Jimmy Romanos - Tyler Rash - Joe Schaeperkoetter - Dave Stalla

University of Missouri, Chemistry Mark Lee, Jr.

Anupam Sing

University of Missouri, International Institute of Nano and Molecular Medicine M. Frederick Hawthorne

Satish Jalisatgi

2

Objectives & Relevance Synthesize boron-doped and nitrogen-doped pore networks, from

polymeric materials, for H2 storage with high surface areas

boron predicted to raise binding energy from 5 kJ/mol to 10-15 kJ/mol

Characterize materials and mechanisms of H2 adsorption

Structure and thermodynamics of adsorbed adsorbed films from 4K to 300 K (subcritical and supercritical adsorption)

Integrated experimental and computational program

carbons offer much richer spectrum of high-capacity adsorbents for H2 than previously appreciated

Function-driven materials design for hydrogen storage (2017 DOE Hydrogen Storage Targets)

3

Background

4 0.0 0.5 1.0 1.5 2.0 2.5 3.0

4

6

8

10

12

14

16

Enth

alpy

of A

dsor

ptio

n (k

J/m

ol)

Absolute Adsorption (wt%)

3K 3K-H60 (I,A)

EERE (2012): decaborane doped activated carbon from corncob (8.6% B:C), 2000-2500 m2/g

~ 2 x binding energy 8.6% B:C

BES (2009): ab initio calculations: enhanced adsorption in B-doped carbon

Approach

5

Why boron-doped carbon via co-polymerization? • Monodisperse boron and narrow pores higher H2 binding energies

• Easier incorporation of boron into the carbon matrix

10 20 30 40 500.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

Diffe

rent

ial P

ore

volu

me

(cm

3 /(Å.g

))Pore Width (Å)

3K HS;0B

HS;0B polymer

precursor

3K lignocellulose

precursor

Technical Accomplishments

6

303 K

80 K

Synthetic Carbon Enhanced Adsorption

Sample Surface Area (m2/g) Porosity Areal Excess @ 303K, 100 bar (µg/m2)

HS;0B-20 synthetic 900 0.46 6.9

3K-600C lignocellulose 2600 0.76 2.9

303 K

80 K

0 50 100 150 2000

2

4

6

8

10

HS;0B-20 3K-600C

Area

l Exc

ess

Adso

rptio

n [µ

g/m

2 ]

Pressure [bar]0 50 100 150 200

0

2

4

6

8

10

12

HS;0B-20 3K-600C

Gra

vimet

ric E

xces

s Ad

sorp

tion

[g/k

g]

Pressure [bar]

0 50 100 150 2000

10

20

30

40

50

HS;0B-20 3K-600C

Area

l Exc

ess

Adso

rptio

n [µ

g/m

2 ]

Pressure [bar]

0 10 20 30 40 500.00

0.02

0.04

0.06

0.08

0.10

0.12

HS;0B-20 3K-600C

dV(w

)/dw

[cm

3 /Å/g

]

Pore Width [Å]

Synthetic carbon, HS:0B, is anomalous: - Maximum in exc. ads. at

higher than normal pressure - Much higher exc. ads. per

unit area than other carbons

7

0 50 100 150 2000

10

20

30

40

50

60

HS;0B-20 3K-600C

Gra

vimet

ric E

xces

s Ad

sorp

tion

[g/k

g]

Pressure [bar]

Hydrogen Film Density

When adsorbed film density is equal to the bulk gas density the excess adsorption is zero

x-intercept should give approximation of adsorbed film density

Saturated film density is ~ twice the liquid density

Synthetic carbons need to be measured at temperatures < 77K to get a strong maximum to perform extrapolation

8

0 20 40 60 80 100 120 140 1600

10

20

30

40

50

60

70

80 K 90 K

Grav

imetr

ic Ex

cess

Ads

orpt

ion

[g/k

g]

H2 Density [g/L]

Sample Saturated Film Density [g/L]

Liquid H2 (at 20 K) 71

3K-600C (from 80 K) 120

3K-600C (from 90 K) 140

Linear Extrapolation (3K-600C)

9

High surface area carbons adsorb helium even at room temperature

True skeletal density, ρ0, determined from Henry’s Law

Extrapolate isotherm to zero pressure where adsorption is negligible

ρ0 = 1.6 ± 0.1 g/cm3

When validated, hydrogen storage on numerous carbons will need to be revised upward

Skeletal Density from Henry’s Law Regime

0 1 2 3 4 5

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0 He Measurement 1 He Measurement 2 Average Interpoation 1 Interpoation 2 Interpolation Average

Skele

tal D

ensit

y [g

/cm3 ]

Pressure [bar]

pk ρρρ ,H0observed +=

Room Temperature Helium Isotherm (3K-600C)

10

High Resolution Transmission Electron Microscopy Oak Ridge National Laboratory

Center for Nanophase Materials Sciences

Aberration corrected STEM

Nion UltraSTEM with 200 kV cold field emission gun

Full 5th order aberration corrector

Measured at 60 kV for carbon

Polymer carbons have regions of graphitic and amorphous carbon consistent with 700 m2/g surface area

11

Temperature: 80 K

Density distribution for participating pores, with carbon volume

represented by grey walls (GCMC)

Second layer formation for pores between 10-20 Å

Numerical Modeling (GCMC)

5 10 15 20 25 30 35 40 45 500.00

0.02

0.04

0.06

0.08

0.10

0.12

5 10 15 20 25 30 35 40 45 500.0

0.5

1.0

1.5

2.0

2.5

Pore

Size

Dist

ribut

ion

Pore width (A)

3K MSC

Cum

ulat

ive p

ore

volu

me

(cc/

g)

Pore width (A)

3K MSC

Experimental pore size distribution from N2 adsorption

at 77 K

12

0 20 40 60 80 1000

20

40

60

80

100

120

N (g

/kg)

Pressure (bar)

MSC-30 3K Total Excess

80 K

0 20 40 60 80 1000

5

10

15

20

25

N (g

/kg)

Pressure (bar)

MSC-30 3K Total Excess

303 K

Bimodal model correctly predicts: Grav. excess adsorption Grav. storage capacity Isotherms at 80 K Isotherms at 303 K

Lines represent the numerical simulation fits: 3K: 50% H13 + 50% H20 (Hxx: slit pore of width xx Å) MSC-30: 50% H8 + 50% H30

Numerical Modeling (cont.)

13

It is shown that the first stage of heating (outgassing) has little effect on the ultimate structure, with characteristic pores forming during the second stage (pyrolysis)

For q<~3x10–3 Å-1, all graphs share a common power law of approximately q-3.6, indicative of a surface fractal network with Ds = 2.4

To study the effect on the nanopores, the data at q>0.3 Å-1 is modeled using a Guinier fit to determine the radius of gyration :

Small Angle X-ray Scattering of Synthetic Carbon

2g( )

( exp3

)q R

I q G=

Stage 1: initial pyrolysis to ~250 C Final: pyrolysis finished to 700-1000 C

14

Small Angle X-ray Scattering

Model HS;

0B-0

HS;

0B-C

La

rge

HS;

0B-C

Sm

all

HS;

0B-2

0

Radius of Gyration 60 Å 70 Å 3 Å 5 Å

Sphere Diameter 140 Å 170 Å 9 Å 12 Å

Circle Diameter 160 Å 190 Å 9 Å 13 Å

Square Side Length 140 Å 160 Å 8 Å 11 Å

Triangle Side Length 190 Å 230 Å 12 Å 16 Å

Ave Pore Width (SAXS, knee)

180 Å 190 Å 16 Å 21 Å

Ave Pore Width (N2 Sorption)

19 Å 20 Å 18 Å

15

Conformability of Pores

16

•! Is there a maximum lateral size for a slit pore? •!Will pores “collapse” if they are too large? •!Does this depend on the presence of adsorbed gas? •! Is there a pressure-dependent pore volume?

!

"#$#%#&'(!!!!E[z(x)]= [2C(!2z)2 +V)**+,(z)"(z)

! "#### $####]dx# $ %"

%z& d

dx%"%z '

'()

*+,+ d 2

dx2

%"%z"

'()

*+,= 0

z

x

!z(

L/2)

(Å)

L (Å)

Center Opening vs. Pore Length

!"

#!"

$!"

%!"

&!"

'!"

(!"

)!"

*!"

+!"

!" $" &" ("

!"#$

%&'($

)*+$,-.)/0

1)

2345+")(6)7$-+"8#9#-+:)*#;+"%)

,-./0123.45"6,"

7482945"6,"

N2 PSD SAXS

2 3 4 5 6 7

Height z (Ang)

L=10L=15L=18L=20L=23L=25

Pore center opening distribution

pore collapse at L ~ 18 Å

Conformability of Pores

17

• Is there a maximum lateral size for a slit pore? • Will pores “collapse” if they are too large? • Does this depend on the presence of adsorbed gas? • Is there a pressure-dependent pore volume?

L = 25 Å @ 30 bar

P ~ 20 bar

L = 20 Å, no gas collapsed pore

L = 25 Å, collapsed pore being filled (~ 1µs, 106 steps)

(pre-filled) Open/close “transition” at ~ 20 bar

GCMC, based on expanding pores

Theory: sub-nm characterization of pores (2011)

Experiment at ORNL (2012)

E1 – E0 = 14.7 meV

Quantum levels for adsorbed H2

IINS peaks vs. pore width

Inci

dent

n: 3

0 m

eV

Inci

dent

n: 9

0 m

eV

6 Å pore 8 Å pore

Incoherent Inelastic Neutron Scattering In

cide

nt n

: 90

meV

18

Incoherent Inelastic Neutron Spectroscopy

19

4

Momentum Transfer

Ener

gy T

rans

fer (

meV

)

2 4 6 8 101020304050607080

E d=14.0

free recoilM=2 amu

recoilM=0.64 amu

FIG. 4. Inelastic neutron scattering intensity map of hydrogenadsorbed in MWCNTs after background subtraction, with in-tensity plotted on a log scale. Incident neutron energy is 90meV and the temperature is 23 K (with gradient as describedin Section II). The main peaks of the rotational and roto-vibrational transitions are identified, and the roto recoil tailis fit with a quadratic function.

when the neutron flips the spin of a proton. Because

protons are fermions, the H2 wavefunction must remain

antisymmetric, requiring a spin flip to be accompanied

by a molecular rotational transition. Pure translational

transitions are proportional to the coherent cross section,

which is over 40 times smaller, and thus are not easily

observed.

Free-recoil generally occurs with a quadratic disper-

sion, ∆E = (�Q)2/2M , where M is the mass of the re-

coiling molecule. Figure 5 shows a spectrum collected

with a 500 meV incident neutron energy. Roto-recoil

tails extend from the J = 0 → 1, 3, 5 transitions and are

fit well with M = 2 amu, consistent with previous work

with a carbon nanotube substrate28. For this spectrum,

the high energy of the incident neutrons and the large

values of Q and ∆E mean that the impulse approxima-

tion can be used and the molecule can largely be treated

classically.

In contrast, the roto-recoil tail of the spectrum in Fig.

4 is best fit with M ≈ 0.64 amu. It was measured using

neutrons with an incident energy of 90 meV and such

small values of Q, that the slow neutron limit is more

appropriate. In this regime, the overlap of the initial and

final wavefunctions with the neutron momentum trans-

fer is used to calculate scattering probabilities. Previ-

ous theoretical work29

in the slow neutron limit finds

M = 1.23 amu for H2, still significantly larger than our

value. A reasonable alternative hypothesis is that there is

coupling between the roto-recoil continuum and the roto-

vibrational state, a possibility which is consistent with

the overlap of the roto-recoil tail and roto-vibrational

peak in both ∆E and Q in Fig. 4. This finding suggests

that the translational motion parallel and perpendicu-

Momentum Transfer (A−1)En

ergy

Tra

nsfe

r (m

eV)

2 6 10 140

100

200

300

400

FIG. 5. Inelastic neutron scattering intensity map of hydrogenadsorbed in 3K, with intensity plotted on a log scale. Inci-dent neutron energy is 500 meV and the temperature is 23K (with gradient as described in Section II). Free recoil lineswith M = 2 amu go through the peaks, extending from theJ = 0 → 1 transition at ∆E=14.7 meV, the the J = 0 → 3transition at ∆E=88.2 meV, and the the J = 0 → 5 transi-tion at ∆E=220.5 meV.

lar to the plane cannot be treated independently of one

another.

IV. DATA ANALYSIS

Earlier experimental work has analyzed the main rota-

tional peak using Gaussians or similar peak shapes after

removal of the recoil as a background,1–4,6,7

often by us-

ing another Gaussian to fit the recoil. However, as we

will show in the next section, rotational and recoil tran-

sitions are not separable due to their mutual dependence

on the orientation of Q, thus such methodology shifts

peak locations and hinders interpretation.

Instead, we begin our analysis with the assumption

that the scattering intensity I(Q,∆E) around the main

rotational peak is composed of two types of excitations.

The first, Ib(Q,∆E), is a narrow peak which represents

rotational excitations that are translationally bound and

exhibit no recoil broadening. The second, Im(Q,∆E),

is a broad peak extending into the high energy region

and represents rotational excitations which are mobile

with respect to their translational motion parallel to the

substrate. In the high-energy region, within the roto-

recoil tail, only mobile transitions are present. Therefore,

to separate mobile and bound states, we wish to perform

a fit to the roto-recoil tail, extend that fit into the main

rotational peak, and subtract it from the experimental

data. Whatever is left should represent the scattering

6

The result represents the experimental intensity of scat-

tering from bound states (Ib Fig. 6c) and is well de-

scribed by a Gaussian in ∆E, consistent with scattering

to a bound state. This justifies a posteriori our initial

assumption of the presence of bound states, as well as

the fitting procedure we have used thus far. Next Ib is

fit over the range ∆E = 13.5-16 meV with

Sb(Q,E) = fe(E−Eb)2/2g2

F⊥(Q)e−hQ2

, (4)

where F⊥(Q) is an isotropic average of our previously

calculated form factor21 for rotational states with per-

pendicular orientation. The function Sb for the MWCNT

sample is shown in Fig. 6d. Likewise,

Im(Q,E) = I(Q,E)− Sb(Q,E) (5)

gives the scattering to mobile states (Ib, Fig. 6e), without

the arbitrary assumptions contained in Eq. 2.

Figure 8 shows the average Q-dependence of Ib and

Im at their respective peak locations, ∆Eb = 14.7 meV

and ∆Em = 13.8 meV. Clearly the two types of tran-

sitions have a significantly different Q-dependence, an-

other a posteriori justification of our assumption of two

different types of excitations. (Because the peak Q of Imshifts upwards as ∆E increases, the difference between

the peak Q locations increases when both are plotted at

the same energy transfer ∆E = 14.7 meV.) The differ-

ence in the Q-dependence of Ib and Im, as well as their

different shapes and peak locations in ∆E (Fig. 9 creates

the distinctive almond shape to the composite rotational

peak visible in experimental spectra (Fig. 6a).

1 2 3 4 5 6Momentum Transfer (A−1)

Aver

age

Inte

nsity

(arb

. uni

ts)

peak of I

b

fit with F!

peak of Im

fit with F||

FIG. 8. Q-dependence of the average intensity in a ∆E = 0.8meV region around the peak location for Ib and Im for theMWCNT sample at a temperature of 23 K (with gradientas described in Section II). Fits to these functions using ourpreviously calculated21 form factors are also shown, where Ibhas been fit with F⊥(Q) and Im has been fit with F||(Q).

We have also shown fits using the isotropic averages

of our previously calculated form factors21 in Figure. 8.

Im has been fit with F||(Q), which seems to describe its

shape reasonably well. On the other hand Ib is not fit

as well with F⊥(Q). The shape of the roto-vibrational

peak (not shown) is also not described as well24. Im-

proved theory with more accurate potentials is needed to

improve these fits. Debye-Waller factors were also calcu-

lated for each sample and coverage using the fits and are

shown below in Table II.

V. PEAK IDENTIFICATION

Inte

nsity

(arb

. uni

ts)

12 14 16 18 20Energy Transfer (meV)

totalspin ||spin !expt.

IIbIm

(a)

(b)

FIG. 9. (a) Experimental intensity I (error bars are smallerthan the symbols) decomposed into Ib (bound) and Im (mo-bile) summed over Q = 2 − 4 A−1 for the MWCNT sam-ple. Incident energy is 30 meV, temperature is 23 K (withgradient as described in Section II). (b) Theoretical neutronscattering spectrum calculated for comparison at Q = 3 A−1

which includes rotational and roto-recoil transitions. The to-tal spectrum is composed of scattering from the parallel andperpendicular orientations of the excited rotational state.

The results of the analysis are demonstrated in Figure

9a, which shows a one-dimensional projection of the ex-

perimental intensity I, decomposed into Ib and Im. It

is notable that the peak locations of Ib and Im are split

in ∆E by 0.9 meV, a significant amount on the order of

the expected splitting of the rotational peak19–21. To ex-

plain the origin of this result and identify the two peaks,

we will now return to a discussion of the relationship of

rotational and recoil transitions.

In our previous calculations21, where we treated trans-

lational and rotational degrees of freedom as indepen-

dent, we showed that neutrons tend to excite rotational

states in which the molecular axis is parallel with Q.

If θ is the angle between Q and the adsorption plane,

the probability that the excited rotational state will be

oriented parallel to the adsorption plane is cos2 θ. Like-

wise, we expect the energy of recoil along the plane to

be proportional to Q2 cos2 θ. Figure 9b demonstrates the

expected result of these two orientational dependencies.

5

from the bound states.

Ener

gy T

rans

fer (

meV

)

Experimental Intensity I

10

15

20

Fit to Roto−Recoil Tail Sm

Bound Intensity Ib

10

15

20

Fit to Bound Intensity Sb

Momentum Transfer (A−1)2 4 6

Momentum Transfer (A−1)

Mobile Intensity Im

2 4 610

15

20

(b)

(c)

(a)

(d)

(e)

FIG. 6. (a) The INS intenstiy map, I, for the MWCNT sam-ple, with an incident energy of 30 meV and temperature of23 K (with gradient as described in Section II). (b) The fit tothe roto-recoil tail extended into the low enegy region, Sm, asdescribed by Eq. 2. (c) The scattered intensity from boundstates, Ib, calculated by Eq. 3. (d) The fit to the bound in-tensity, Sb, as described by Eq. 4. (e) The scattered intensityfrom mobile states, Im, calculated by Eq. 5. All plots areshown on the same intensity scale which starts at zero andhas been chosen to show the roto-recoil tail well, saturatingthe rotational peak. Axis values are the same for each panel.

Our analysis utilizes the full two-dimensional intensity

map of each sample. The intensities and fits for each

step of the analysis are shown in Figure 6. To iden-

tify an effective fitting function for the roto-recoil tail

which uses the entire two-dimensional data set, we ob-

serve that the Q-dependence of the roto-recoil tails in

Fig. 1 seem to remain quite similar in shape as energy

transfer increases, but shifts by the recoil momentum

QR =�

2M(E − Ed)/�. This behavior is illustrated

in Figure 7, which shows the Q-dependence of the roto-

recoil tail at several values of ∆E, which were chosen

to lie outside of the main rotational and roto-vibrational

peaks. The values of M=0.64 amu and ∆Ed = 14.0 meV

are determined by a quadratic fit of the roto-recoil tail

in the 90 meV intensity map over the ranges ∆E = 17-

22 meV and 32-63 meV (outside of the main peaks), as

shown in Figure 4. We find that these values vary little

from sample to sample.

Therefore, we perform Q-dependent fits of the 30 meV

incident energy spectrum (shown in Fig. 6a for the

MWCNT) for each value of energy transfer in the range

2 4 6 8 10Momentum Transfer (A−1)N

orm

aliz

ed In

tens

ity (a

rb. u

nits

)

E=20 meV,QR=1.30 A!1

E=23 meV,QR=1.62 A!1

E=26 meV,QR=1.87 A!1

FIG. 7. Q-dependence of the roto-recoil tail at several differ-ent values of ∆E for the MWCNT sample. Incident neutronenergy is 90 meV and the temperature is 23 K (with gradientas described in Section II). The value of the recoil momentumQR is given at each ∆E. They are quite similar to each otherin shape, but shifted in Q relative to the recoil momentum.

∆E = 17-22 meV using the following function,

S(Q) = AF||(Q−QR)e−BQ2

, (1)

where F||(Q) is an isotropic average of our previously

calculated form factor21 for rotational states with parallel

orientation. We will justify our choice of form factors

in the next section. The values of A and B are both

observed to drop slowly with increasing ∆E, and are fit

with A(∆E) = a + b∆E and B(∆E) = dec∆E . These

parameters are then used used to describe the scattering

to mobile states;

Sm(Q,E) = (a+ b∆E)F||(Q−QR)e−exp(c∆E)dQ2

, (2)

where the function Sm for the MWCNT sample is shown

in Fig. 6b. Because Sm was chosen to describe the roto-

recoil tail, it clearly does not describe the scattering from

mobile states well on the low energy side of the main rota-

tional peak. Instead, the full scattering from the mobile

states is extracted below (using Eq. 5). Improved the-

ory is required to refine Eq. 2. This will permit more

traditional fitting techniques, in which the intensity is

described as a sum of one or more curves whose param-

eters are varied until the ideal fit is found. In contrast,

the purpose of this analysis technique is to utilize the

two-dimensional data set to remove the recoiling part of

the spectrum, in order to see the magnitude and shape

of the remaining intensity and assess what features are

lacking from current theory.

Next, Sm is extended past the main rotational peak,

to ∆E=5 meV, and subtracted from the experimental

intensity,

Ib(Q,E) = I(Q,E)− Sm(Q,E). (3)

Decomposition into mobile and bound adsorbed H2 states (2011-12)

9

10 12 14 16 18

Rel

ativ

e In

tens

ity

Energy Transfer (meV)

MWNCTMSC−303KHS;0B

(b) Ib

(a) Im

FIG. 12. Experimental neutron scattering spectrum summed

over all Q separated into (a)Im and (b)Ib for hydrogen in sev-

eral carbon adsorbents. Spectra are normalized to the amount

of hydrogen in the sample.

is slightly wider. The area of Ib for the ACs is ≈ 105%that of the MWCNT sample, and is significantly wider,consistent with a greater amount of surface heterogene-ity.

The fact that the MWCNT and AC samples are sosimilar, despite significant differences in their pore sizedistributions (Fig. 2), is further evidence against an in-terpretation which would identify Ib with H2 moleculesimmobilized in the smallest pores. Using instead the in-tepretation we have offered in this paper, the small de-crease in scattering to mobile states and small increase inscattering to bound states of the ACs is consistent withslightly decreased planarity of the adsorption surfaces inAC.

We have collected transmission electron microscopy(TEM) images with a JEOL 1400 transmission electronmicroscope operated at 120 KeV. Images of 3K (notshown)24 depict randomly oriented irregularly shapedpores with widths on the order of 10 A and lengths of sev-eral nanometers, similar to TEM images of many otherACs17. At this resolution, individual atoms cannot beseen and the maximum contrast is when atomic sheets areviewed edge-on. Abberation corrected images of NoritGSX AC35 are able to detect individual atoms and imageatomic sheets along their length, and this AC is seen to becomposed of graphene-like sheets with mostly hexagonalrings, with some pentagonal rings which cause curvatureof the sheets. This structural model is consistent bothwith our TEM images and the IINS results, as well aspreviously proposed models of AC composed of graphene-like plaquettes17 which have only a small amount of cur-vature along the plane on the nanometer length scale.

Table II also gives the Debye-Waller factors for all sam-ples as a function of coverage, and they are also quiteconsistent between the MWCNT and AC samples. Thefinding that these values decreases as a function of cov-erage for each sample is consistent with the interpreta-

TABLE I. Peak location (meV), width (meV), and area (arb.

units) of the mobile and bound states, calculated from the 30

meV spectra as for each sample. The step size in ∆E is 0.05

meV, and the resolution at 14.7 meV is 0.7 meV. *The half

width at half maximum (HWHM) is given for Im and gives the

distance between the peak and the location of half intensity

on the low energy side.+The area is equal to the intensity

summed over all Q and ∆E=5–22 meV and is normalized by

the unity area of Ib for the MWCNT.

Im Im Im Ib Ib Ib Ib/peak HWHM* area

+peak FWHM area

+ ImMWCNT 13.82 1.04 3.97 14.63 1.06 1.00 0.25

MSC-30 13.82 1.19 3.77 14.68 1.44 1.04 0.28

3K 13.88 1.15 3.75 14.68 1.34 1.06 0.28

HS;0B 13.57 1.89 5.47 14.68 1.55 1.22 0.22

tion of the Debye-Waller factor as the average variancein position of the center of mass of the initial state of themolecule along the direction of Q, as well as our expecta-tion that increasing coverage tends to localize molecules.The finding that the Debye-Waller factor of Ib tends tobe larger than that of Im supports our assertion thatIb represents excitations where Q has a large compo-nent perpendicular to the adsorption plane. The narrowadsorption potential means that molecules are stronglyquantized perpendicular to the plane, making them moredelocalized in this direction.

TABLE II. Debye-Waller factors in A2of the mobile and

bound states, calculated from the 30 meV spectra as a func-

tion of sample and coverage.

Im Im Im Ib Ib Ibcoverage 60% 90% 120% 60% 90% 120%

MWCNT 0.085 0.081 0.103 0.098

MSC-30 0.084 0.079 0.106 0.090

3K 0.086 0.079 0.077 0.100 0.085 0.081

HS;0B 0.074 0.073 0.069 0.057 0.054 0.051

The results for HS;0B reveal that most of the differ-ence in its spectrum is contained within Im, which islarger, asymetrically broadened, and peaks at a signifi-cantly lower energy. Ib and the roto-vibrational peak donot move compared to the other samples, although bothdo broaden. The Debye-Waller factors are also signifi-cantly different from those of the other samples. Becausethe presence of a significant number of sub-nanometerpores would result in changes to all peak locations21, wemust look for another structural feature which explainsthe results for this sample. Asymmetrical broadeningof scattering peaks is typically explained by the Fano

Interpretation: Similarities of spectra for samples with very different PSDs suggest* very few sub-nm pores in AC, most pores with similar binding energies. *Except HS;0B

Two types of states: mobile & bound, different adsorption properties? (Burress et al., Nanotechnology 2009) Different weights of Sm and Sb in different samples indicate (small) differences in the degree of “planarity” of the substrate on a supra-nm scale. The area of Sm peak for the ACs is ~ 95% of that of the MWCNTs (a nominally smooth surface), and the area of Sb is 105% for ACs vs. MWCNTs, while significantly wider. Interpretation: AC’s are almost as smooth as MWCNTs (at 1-2 nm lengths).

Sievert Apparatus

20

Pressure range

0-200 bar

Temperature range

8-500 K using closed cycle refrigerator

Temperature stability

±0.01 K

Sample size: 0.5-2 g

Gases: helium, hydrogen, methane, mixtures, etc…

Allow hydrogen BET measurements using subcritical hydrogen

Pneumatic controlled valve

Needle valve

To sample cell in CCR

340 bar transducer

2 bar transducer

Additional dosing

volume

Hydrogen

Helium

Vacuum

Polyphenylene model based on concepts of Gibson et al. (1946) and Riley (1947)

The model of Kaneko (1992)

Mol # of C size(nm) Surface

(m2g-1) A 56 1.1x2.1 5800 B 71 1.5x2.1 6000 C 110 1.5x2.6 4700 D 158 1.5x3.5 4400 E 212 1.9x3.5 4100

Geometrically Optimized Models for Adsorption

Model: adsorption on “circular” fragments Competition between

increasing surface and weaker binding

energy

21

-10 0 10 20 30 40

-10

0

10

20

30

40

Y (A

)

X (A)-40 -30 -20 -10 0 10 20 30 40

-40

-30

-20

-10

0

10

20

30

40

Y (A

)

X (A)

-80 -60 -40 -20 0 20 40 60-80

-60

-40

-20

0

20

40

60

Y (A

)

X (A)

-40 -30 -20 -10 0 10

-10

0

10

20

30

40

Y (A

)

X (A)

3D-Patch 3D-Ortho

Open Carbon Frameworks (GCMC)

Graphene

PAF

T = 77 K

T = 300 K

Open symbols: energy of adsorption doubled

22

0 2 0 4 0 6 0 8 0 1 0 0 0

2 0

4 0

6 0

T o t

a l ( g

/ k g

)

p r e s s u r e ( b a r )

3 D P a t c h 3 D C u b i c

0 2 0 4 0 6 0 8 0 1 0 0 0

2 0

4 0

6 0

8 0

1 0 0

E x c

e s s

( g

/ k g

)

p r e s s u r e ( b a r )

Open Carbon Frameworks (GCMC) Performance Comparison: PAF, graphene, OCF’s, Coronene/Benzene

23

Project Summary, 2011-12

24

Polymeric carbon enhanced adsorption PVDC carbons show enhanced hydrogen sorption compared to lignocellulose-precursor

carbon due to dominance of nanopores

Hydrogen film density & thickness Hydrogen film density determined from extrapolation of high pressure hydrogen sorption

measurements is ~ twice that of liquid hydrogen Elimination of unphysical rise in isosteric heat gives an lower bound to the film thickness

HRTEM Synthetic carbons have regions of graphite and amorphous carbon

Small angle X-ray scattering Two shoulders in scattering lead to a large and small structure, the small structure is likely

pores whereas the large structure is likely regions of graphite as seen in HRTEM

Conformability of pores The graphene layers may flex and move with increased pressure

Incoherent inelastic neutron spectroscopy Two dominant states emerge, mobile and bound

Open carbon frameworks New theoretical structures will give insight into new materials to be synthesized and the

effect of surface area and biding energy in predominantly carbon systems

Future Work: Plans for 2012/13

25

Polymeric carbons New copolymerization routes utilizing poly(vinylidene chloride) or poly(vinyl alcohol) with

boronic acids or vinyl carboranes

Neutrons IINS further investigate hydrogen interactions with boron containing substrate at different

temperatures and coverages

Aberration corrected STEM Explain interesting behavior of polymer-based pure carbons Identify position of boron atoms with EELS

Sieverts Perform low temperature studies of b-doped carbons both at subcritical (hydrogen BET) and

supercritical conditions

Hydrogen measurements Higher pressure measurements on higher binding energy materials to better determine

hydrogen film density Study Henry’s law regime to experimentally determine binding energies and vibrational

frequencies of hydrogen in b-doped systems

Simulations GCMC of different optimized structures Conformable pores

Supplemental Slides

26

Publications In Progress:

The Quantum Excitation Spectrum of Adsorbed Hydrogen, R. Olsen, M. Beckner, P. Pfeifer, C. Wexler, and H. Taub, Phys. Rev. Lett. (under review).

Functional B-C Bonds in Nanoporous Boron Carbide and Boron Doped Carbon Materials, J. Romanos, D. Stalla, M. Beckner, A. Tekeei, G. Suppes, S. Jalisatgi, M. Lee, F. Hawthorne, D. Robertson, L. Firlej, B. Kuchta, C. Wexler, P. Yu, P. Pfeifer, Carbon (under review).

Elastic Pore Structure of Activated Carbon, M.J. Connolly and C. Wexler, Phys. Rev. B.

Boron Doping of Activated Carbons Using Decaborane, M.J. Connolly, M.W. Beckner, and C. Wexler, Langmuir.

Infrared Study of Boron-Carbon Chemical Bonds in Boron Doped Activated Carbon, J. Romanos, M. Beckner , D. Stalla, A. Tekeei, G. Suppes, S. Jalisatgi, M. Lee, F. Hawthorne, J. D. Robertson, L. Firlej, B. Kuchta, C. Wexler, P. Yu, and P. Pfeifer.

Published:

Nanospace engineering of KOH activated carbon, J. Romanos, M. Beckner, T. Rash, L. Firlej, B. Kuchta, P. Yu, G. Suppes, C. Wexler, and P. Pfeifer, Nanotechnology 23, 015401 (2012).

Hydrogen Adsorption Studies of Engineered and Chemically Modified Activated Carbons, M. Beckner, Ph.D. Thesis (University of Missouri, 2012).

Nanospace Engineering of Porous Carbon For Gas Storage, J. Romanos, Ph.D. Thesis (University of Missouri, 2012).

Numerical Analysis of Hydrogen Storage in Carbon Nanopores, C. Wexler, R. Olsen, P. Pfeifer, B. Kuctha, L. Firlej, Sz. Roszak, in Condensed Matter Theories Vol. 25, Eds. E.V. Ludeña, R.F. Bishop, & P. Iza (Nova Science Publishers, 2011).

27

Publications Sub-Nanometer Characterization of Activated Carbon by Inelastic Neutron Scattering, R.J. Olsena, L. Firlej, B.

Kuchta, H. Taub, P. Pfeifer, & C. Wexler, Carbon 49, 1663-1671 (2011).

Influence of Structural Heterogeneity of Nano-Porous Sorbent Walls on Hydrogen Storage, B. Kuchta, L. Firlej, Sz. Roszak, P. Pfeifer, & C. Wexler, Appl. Surf. Sci. 256, 5270–5274 (2010).

Numerical Estimation of Hydrogen Storage Limits in Carbon Based Nanospaces, B. Kuchta, L. Firlej, P. Pfeifer, & C. Wexler, Carbon 48, 223-231 (2010).

A Review of Boron Enhanced Nanoporous Carbons for Hydrogen Adsorption: Numerical Perspective, B. Kuchta, L. Firlej, Sz. Roszak, & P. Pfeifer, Adsorption 16, 413-421 (2010).

Structural & Energetic Factors in Designing a Nanoporous Sorbent for Hydrogen Storage, B. Kuchta, L. Firlej, R. Cepel, P. Pfeifer, & C. Wexler, Colloids Surf. A: Physicochem. Eng. Aspects 357, 61–66 (2010).

Numerical Analysis of Hydrogen Storage in Carbon Nanopores, C. Wexler, R. Olsen, P. Pfeifer, B. Kuchta, L. Firlej, Sz. Roszak, Int. J. Mod. Phys. B 24, 5152-5162 (2010).

Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage, P. Pfeifer, C. Wexler, G. Suppes, F. Hawthorne, S. Jalisatgi, M. Lee, & D. Robertson, DOE Hydrogen Program 2010 Annual Progress Report, http://www.hydrogen.energy.gov/annual_progress10. html, p. 474-480.

Fundamental Building Blocks of Nanoporous Networks from Ultra-Small-Angle X-Ray Scattering (USAXS) & Small-Angle X-Ray Scattering (SAXS) Experiments. M. Kraus, Ph.D. Thesis (University of Missouri, 2010).

Enhanced Hydrogen Adsorption in Boron Substituted Carbon Nanospaces; L. Firlej, Sz. Roszak, B. Kuchta, P. Pfeifer, & C. Wexler, Virt. J. Nanoscale Sci. Technol. 20, 19 (2009) [editor selection].

28

Publications Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage, P. Pfeifer, C. Wexler, G.

Suppes, F. Hawthorne, S. Jalisatgi, M. Lee, & D. Robertson, DOE Hydrogen Program 2009 Annual Progress Report, http://www.hydrogen.energy.gov/annual_progress09. html, p. 646-651.

Enhanced Hydrogen Adsorption in Boron Substituted Carbon Nanospaces, L. Firlej, Sz. Roszak, B. Kuchta, P. Pfeifer, & C. Wexler, J. Chem. Phys. 131, 164702 (2009).

Hydrogen Storage in Engineered Carbon Nanospaces; J. Burress, M. Kraus, M. Beckner, R. Cepel, G. Suppes, C. Wexler, & P. Pfeifer; Nanotechnology 20, 204026 (2009). Featured in http://www.physorg.com/news162195986.html

Boron Substituted Graphene: Energy Landscape for Hydrogen Adsorption; L. Firlej, B. Kuchta, C. Wexler, & P. Pfeifer; Adsorption 15, 312 (2009).

Gas Sorption in Engineered Carbon Nanospaces, J. Burress, Ph.D. Thesis (University of Missouri, 2009).

29

Presentations Elastic Pore Structure of Activated Carbon, M. Connolly and C. Wexler, The 6th International Workshop on

Characterization of Porous Materials–from Angstroms to Millimeters (CPM-6), Delray Beach, FL, April-May, 2012.

Recoiling and Bound Quantum Excitations of Adsorbed Hydrogen As An Assessment of Planarity, R. Olsen, H. Taub and C. Wexler, The 6th International Workshop on Characterization of Porous Materials–from Angstroms to Millimeters (CPM-6), Delray Beach, FL, April-May, 2012.

Boron Doping Carbon Structures Using Decaborane: A Theoretical Study, C. Wexler, M. Connolly, M. Beckner, and P. Pfeifer, March 2012 Meeting of the American Physical Society (Bull. Am. Phys. Soc. 57, W33.01 (2012)), Boston, MA, March 2012.

Industrial Scale Measurements of Hydrogen Uptake and Delivery, T. Rash, D. Stalla, M. Beckner, J. Romanos, G. Suppes, A. Tekeei, P. Buckley, P. Doynov, and P. Pfeifer, March 2012 Meeting of the American Physical Society (Bull. Am. Phys. Soc. 57, W33.04 (2012)), Boston, MA, March 2012.

Reversible Storage of Hydrogen and Natural Gas in Nanospace-Engineered Activated Carbons, J. Romanos, M. Beckner, T. Rash, P. Yu, G. Suppes, and P. Pfeifer, March 2012 Meeting of the American Physical Society (Bull. Am. Phys. Soc. 57, W33.05 (2012)), Boston, MA, March 2012.

Measured Enthalpies of Adsorption of Boron-Doped Activated Carbons, M. Beckner, J. Romanos, E. Dohnke, A. Singh, J. Schaeperkoetter, D. Stalla, J. Burress, S. Jalisatgi, G. Suppes, M. F. Hawthorne, P. Yu, C. Wexler, and P. Pfeifer, March 2012 Meeting of the American Physical Society (Bull. Am. Phys. Soc. 57, W33.07 (2012)), Boston, MA, March 2012.

Performance of Carbon Hydrogen Storage Materials as a Function of Post-Production Thermal Treatment, E. Dohnke, J. Romanos, M. Beckner, J. Burress, P. Yu, and P. Pfeifer, March 2012 Meeting of the American Physical Society (Bull. Am. Phys. Soc. 57, W33.08 (2012)), Boston, MA, March 2012.

30

Presentations The Stationary States of Adsorbed Hydrogen, R. Olsen, H. Taub, and C. Wexler, March 2012 Meeting of the

American Physical Society (Bull. Am. Phys. Soc. 57, W33.06 (2012)), Boston, MA, March 2012.

Measured Enthalpies of Adsorption of Boron-Doped Activated Carbons, M. Beckner, J. Romanos, E. Dohnke, A. Singh, J. Schaeperkoetter, D. Stalla, J. Burress, S. Jalisatgi, G. Suppes, M.F. Hawthorne, P. Yu, C. Wexler, and P. Pfeifer, March 2012 Meeting of the American Physical Society (Bull. Am. Phys. Soc. 57, W33.07 (2012)), Boston, MA, March 2012.

Adsorption-induced Pore Expansion and Contraction in Activated Carbon, M. Connolly and C. Wexler, March 2012 Meeting of the American Physical Society (Bull. Am. Phys. Soc. 57, X11.11 (2012)), Boston, MA, March 2012.

Nanoporous Carbon for Reversible Storage of Hydrogen, C. Wexler, Low Carbon Earth Summit-2011 (LCES-2011), Dalian, China, October 2011.

The Quantum Excitation Spectrum of Adsorbed Hydrogen, R. Olsen, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

Open Carbon Frameworks (OCF) – new hypothetical structures for hydrogen storage, B. Kuchta, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

Influence of edges on adsorption in nanopores with finite pore walls from truncated graphene, L. Firlej, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

Nanospace-Engineered Carbons for Reversible On-Board Storage of Natural Gas and Hydrogen, J. Romanos, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

Analysis of hydrogen sorption characteristics of boron-doped activated carbons, M. Beckner, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

31

Presentations Flexible Pore Walls in Activated Carbon, M. Connolly, International Workshop: Adsorption at the Nanoscale, a

New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

The effect of KOH:C and activation temperature on hydrogen storage capacities of activated carbons, T. Rash, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

Boron-neutron Capture on Activated Carbon for Hydrogen Storage, J. Romanos, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

A high volume, high throughput volumetric sorption analyzer, Y. Soo, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

Nanopore structure from small angle and ultra-small angle x-ray scattering in engineered activated carbons for hydrogen storage, D. Stalla, International Workshop: Adsorption at the Nanoscale, a New Frontier in Fundamental Science & Applications, Columbia, MO, September 2011.

Inelastic Neutron Scattering from Hydrogen Adsorbed in Carbon, C. Wexler, R. Olsen, H. Taub, P. Pfeifer, M. Beckner, Gordon Research Conference “Nanoporous Materials & Their Applications”, Holderness, NH, August 2011.

Characterization of activated carbon atsub-nm scale via adsorption (H2, N2, CH4, isosteric heats), TEM, FT-IR, neutron (IINS) & x-ray (SAXS/USAXS); & application towards optimization of H2 storage, C. Wexler, P. Pfeifer, M. Kraus, M. Beckner, J. Romanos, D. Stalla, T. Rash, H. Taub, P. Yu, R. Olsen, & J. Ilavsky, 9th International Symposium onCharacterisation of Porous Solids (COPS 9), DECHEMA (Gesellschaft für Chemische Technik und Biotechnologie e.V.), Dresden, Germany, June 2011.

Inelastic neutron scattering from adsorbed hydrogen, R. Olsen, M. Beckner, C. Wexler, H. Taub & P. Pfeifer, Wilhelm & Else Heraeus Seminar: Energy Materials Research by Neutrons & Synchrotron Radiation, Bad Honnef, Germany, May 2011.

32

Presentations Nanopore structure from small angle & ultra-small angle x-ray scattering in engineered activated carbons for

hydrogen storage, D. Stalla, M. Kraus, J. Romanos, M. Beckner, J. Ilavsky, C. Wexler, & P. Pfeifer, Wilhelm & Else Heraeus Seminar: Energy Materials Research by Neutrons & Synchrotron Radiation, Bad Honnef, Germany, May 2011.

Insights onpore structure of activated carbon, M. Connolly & C. Wexler, USC-Department of Energy Conference on Materials for Energy Applications—Experiment, Modeling & Simulations, Terranea, CA, April 2011.

A Nanoporous Carbon "Sponge" for Hydrogen Storage, C. Wexler, Physics Colloquium, SUNY-Buffalo, Buffalo, NY, April 2011.

Anomalous Characteristics of a PVDC Carbon Adsorbant, C. Wexler, M. Beckner, J. Romanos, T. Rash, P. Pfeifer, & R. Olsen, March 2011 Meeting ofAmerican Physical Society (Bull. Am. Phys. Soc. 56, H20.09 (2011)), Dallas, TX, March 2011.

Evaluation of isosteric heat of adsorption at zero coverage for hydrogen on activated carbons, E. Dohnke, M. Beckner, J. Romanos, R. Olsen, C. Wexler, & P. Pfeifer, March 2011 Meeting ofAmerican Physical Society (Bull. Am. Phys. Soc. 56, H20.10 (2011)), Dallas, TX, March 2011.

Inelastic Neutron Scattering from Hydrogen Adsorbed in Carbon, R. Olsen, M. Beckner, P. Pfeifer, & C. Wexler, March 2011 Meeting ofAmerican Physical Society (Bull. Am. Phys. Soc. 56, H20.11 (2011)), Dallas, TX, March 2011.

Analysis of hydrogen sorption characteristics of boron- doped activated carbons M. Beckner, J. Romanos, D. Stalla, E. Dohnke, A. Singh, M. Lee, G. Suppes, M.F. Hawthorne, P. Yu, C. Wexler, & P. Pfeifer, March 2011 Meeting ofAmerican Physical Society (Bull. Am. Phys. Soc. 56, H20.12 (2011)), Dallas, TX, March 2011.

33

Presentations The effect of KOH:C & activation temperature on hydrogen storage capacities of activated carbons, T. Rash, M.

Beckner, J. Romanos, E. Leimkuehler, A. Tekeei, G. Suppes, C. Wexler, & P. Pfeifer, March 2011 Meeting ofAmerican Physical Society (Bull. Am. Phys. Soc. 56, H20.13 (2011)), Dallas, TX, March 2011.

Opening of slit-shaped pores from bending of graphene walls, M. Connolly & C. Wexler, March 2011 Meeting ofAmerican Physical Society (Bull. Am. Phys. Soc. 56, T31.11 (2011)), Dallas, TX, March 2011.

A high volume, high throughput volumetric sorption analyzer, Y.C. Soo, M. Beckner, J. Romanos, C. Wexler, & P. Pfeifer, March 2011 Meeting ofAmerican Physical Society (Bull. Am. Phys. Soc. 56, V20.03 (2011)), Dallas, TX, March 2011.

Explaining Hydrogen Adsorption of a Carbon Adsorbant Manufactured by Pyrolosis of Saran, R. Olsen & C. Wexler, Physics Colloquium, University of Northern Iowa, Cedar Falls, IA, January 2011.

Inelastic Neutron Scattering from Adsorbed Hydrogen, R. Olsen, M. Beckner, H. Taub, & C. Wexler, Fall 2010 Meeting of Prairie Section of American Physical Society, Chicago, IL, November 2010.

A Brief History of Energy, C. Wexler, Global Issues Colloquium (Public Lecture), C. Wexler Truman State University, Kirksville, MO, September 2010.

Adsorption of Hydrogen in Boron Substituted Carbon-Based Porous Materials, L. Firlej, B. Kuchta, P. Pfeifer, & C. Wexler, 10th International Conference on Fundamentals of Adsorption (FOA10), Awaji, Hyogo, Japan, May 2010.

Characterization of Sub-nm Pores in Carbon by Inelastic Neutron Scattering, R. Olsen, B. Kuchta, L. Firlej, P. Pfeifer, H. Taub, & C. Wexler, 10th International Conference on Fundamentals of Adsorption (FOA10), Awaji, Hyogo, Japan, May 2010.

High Storage Capacity of Hydrogen in Heterogeneous Carbon Nanopores: Experimental, Theoretical & Computational Characterization, C. Wexler, R. Olsen, M. Kraus, M. Beckner, B. Kuchta, L. Firlej, & P. Pfeifer, 10th International Conference on Fundamentals of Adsorption (FOA10), Awaji, Hyogo, Japan, May 2010.

34

Presentations Engineering a nanoporous “sponge” for hydrogen storage, C. Wexler, Colloquium, Department of Physics,

University of Vermont, Burlington, VT, April 2010.

Hydrogen Absorption in Nanoporous Carbon, C. Wexler, Condensed Matter Seminar, Washington University, St. Louis, MO, April 2010.

A Brief History of Energy, C. Wexler, Public lecture in Saturday Morning Science, http://satscience.missouri.edu, Columbia, MO, February 2010.

Record Hydrogen Storage Capacities in Advanced Carbon Storage Materials, C. Wexler, M. Beckner, J. Romanos, J. Burress, M. Kraus, R. Olsen, E. Dohnke, S. Carter, G. Casteel, B. Kuchta, L. Firlej, E. Leimkuehler, A. Tekeei, G. Suppes, & P. Pfeifer, March 2010 Meeting of American Physical Society (Bull. Am. Phys. Soc. 55, T30.07 (2010)), Portland, OR, March 2010.

Adsorption of Hydrogen in Boron-Substituted Nanoporous Carbons, L. Firlej, B. Kuchta, Ss. Roszak, P. Pfeifer, & C. Wexler, March 2010 Meeting of American Physical Society (Bull. Am. Phys. Soc. 55, T30.09 (2010)), Portland, OR, March 2010.

Isosteric Heats of Adsorption for Activated Carbons Made from Corn Cob, M. Beckner, R. Olsen, J. Romanos, J. Burress, E. Dohnke, S. Carter, G. Casteel, C. Wexler, & P. Pfeifer, March 2010 Meeting of American Physical Society (Bull. Am. Phys. Soc. 55, T30.10 (2010)), Portland, OR, March 2010.

Quantization of Adsorbed Hydrogen for Inhomogeneous Materials Characterization using Inelastic Neutron Scattering, R. J. Olsen, L. Firlej, B. Kuchta, P. Pfeifer, H. Taub, & C. Wexler, March 2010 Meeting of American Physical Society (Bull. Am. Phys. Soc. 55, T30.11 (2010)), Portland, OR, March 2010.

Nanopore Structure from USAXS/SAXS in Advanced Carbon Materials for Hydrogen Storage, M. Kraus, J. Ilavsky, M. Beckner, D. Stalla, C. Wexler, & P. Pfeifer, March 2010 Meeting of American Physical Society (Bull. Am. Phys. Soc. 55, T30.12 (2010)), Portland, OR, March 2010.

35

Presentations Fractal Analysis of Boron Doped Activated Carbon, M. Kraus, C. Wexler, & P. Pfeifer, March 2010 Meeting of

American Physical Society (Bull. Am. Phys. Soc. 55, T30.13 (2010)), Portland, OR, March 2010.

A study of nanoporous activated carbon morphology, structure & functionality using ultra-small-angle & small-angle x-ray scattering, M. Kraus, Report & oral presentation, Comprehensive Examination (Ph.D. admission), Department of Physics, University of Missouri, Columbia, December 2009.

Nano research at MU-Physics, P. Pfeifer, invited presentation at Missouri Nano Frontiers, Columbia, MO, November 2009.

Natural Gas & Hydrogen Storage for Advanced Transportation, P. Pfeifer, invited presentation, MU Research & Development Advisory Board, University of Missouri, Columbia, November 2009.

Structural & Energetic Factors in Designing a Perfect Nano-Porous Sorbent for Hydrogen Storage, B. Kuchta, L. Firlej, R. Cepel, P. Pfeifer, & C. Wexler, Missouri Nano Frontiers, Columbia, MO, November 2009.

Quantum Energy Levels of Hydrogen Adsorbed on Nanoporous Carbons, R. Cepel, B. Kuchta, L. Firlej, P. Pfeifer, & C. Wexler, Missouri Nano Frontiers, Columbia, MO, November 2009.

Small-angle x-ray scattering: rebuilding a three dimensional structure with one dimensional data, M. Kraus, oral presentation at2009 Physics Leaders Meeting, Department of Physics, University of Missouri, Columbia, October 2009.

Carbon nanospaces for high-capacity hydrogen storage, J. Romanos, oral presentation at2009 Physics Leaders Meeting, Department of Physics, University of Missouri, Columbia, October 2009.

Hydrogen storage in engineered carbon nanospaces, C. Wexler, oral presentation at2009 Physics Leaders Meeting, Department of Physics, University of Missouri, Columbia, October 2009.

Hydrogen Adsorption in Boron Doped Nanoporous Carbon, C. Wexler, P. Pfeifer, Sz. Roszak, B. Kuchta, & L. Firlej, 33rd International Workshop in Condensed Matter Theories (CMT33), Ecuador, August 2009. 36

Presentations Influence of Structural Heterogeneity of Nano-Porous Sorbent Walls on Hydrogen Storage, B. Kuchta, L. Firlej, R.

Cepel, C. Wexler, & P. Pfeifer, Seventh International Symposium Effects of Surface Heterogeneity in Adsorption & Catalysis on Solids (ISSHAC-7), Poland, July 2009.

Hydrogen Storage in Engineered Carbon Nanospaces: Experimental Results & Theoretical/Computional Analysis, C. Wexler, J. Burress, R. Cepel, B. Kuchta, L. Firlej, & P. Pfeifer, Seventh International Symposium Effects of Surface Heterogeneity in Adsorption & Catalysis on Solids (ISSHAC-7), Poland, July 2009.

Hierarchical Pore Structure Analysis of Engineered Carbon Nanospaces, M. Kraus, M. Beckner, J. Burress, J. Ilavsky, C. Wexler, & P. Pfeifer, 5th International Workshop on Characterization of Porous Materials, Rutgers University, New Brunswick, June 24-26, 2009.

Structural & Energetic Factors in Designing a Perfect Nanoporous Sorbent for Hydrogen Storage, B. Kuchta, L. Firlej, R. Cepel, P. Pfeifer, & C. Wexler, 5th International Workshop on Characterization of Porous Materials, Rutgers University, New Brunswick, June 24-26, 2009.

Boron-Doped Carbon Nanospaces for High-Capacity Hydrogen Storage, M. Beckner, J. Burress, C. Wexler, Z. Yang, F. Hawthorne, & P. Pfeifer, 2009 March Meeting of American Physical Society, Pittsburgh, PA, March 16-20, 2009. Abstract: Bull. Am. Phys. Soc. 54, W27.00010 (2009).

Analysis of Hydrogen Adsorption in Engineered Carbon Nanospaces, J. Burress, M. Beckner, N. Kullman, R. Cepel, C. Wexler, & P. Pfeifer, 2009 March Meeting of American Physical Society, Pittsburgh, PA, March 16-20, 2009. Abstract: Bull. Am. Phys. Soc. 54, W27.00012 (2009).

Ultra-Small-Angle X-Ray Scattering of Nanoporous Carbons, M. Kraus, M. Beckner, J. Burress, & P. Pfeifer, 2009 March Meeting of American Physical Society, Pittsburgh, PA, March 16-20, 2009. Abstract: Bull. Am. Phys. Soc. 54, W27.00011 (2009).

37

Presentations Structural & Energetic Factors in Designing a Perfect Nanoporous Sorbent for Hydrogen Storage, B. Kuchta, L.

Firlej, R. Cepel, P. Pfeifer, & C. Wexler, 2009 March Meeting of American Physical Society, Pitts-burgh, PA, March 16-20, 2009. Abstract: Bull. Am. Phys. Soc. 54, W27.00014 (2009).

Magnetic Properties of High-Surface-Area Carbons & their Effect on Adsorbed Hydrogen, J. Romanos, R. Cepel, M. Beckner, M. Kraus, J. Burress, & P. Pfeifer, 2009 March Meeting of American Physical Society, Pittsburgh, PA, March 16-20, 2009. Abstract: Bull. Am. Phys. Soc. 54, W27.00009 (2009).

38

Materials for H2 Storage

39

possible enhancement if EB ~ 12 kJ/mol (5-10% B:C)

303 K

80 K

Gravimetric Storage Capacity (g/kg material)

Vol

umet

ric S

tora

ge C

apac

ity (g

/L m

ater

ial)