IPEK YUCELEN
GEORGIA INSTITUTE of TECHNOLOGY
School of Materials Science and Engineering
Nano@Tech
ADVISERS: Prof. SANKAR NAIR
School of Chemical & Biomolecular Engineering
Prof. HASKELL W. BECKHAM
School of Materials Science and Engineering
Single-Walled Metal Oxide Nanotubes
2.2 nm
y
1.0 nm
Ball-and-stick models of (left) the aluminosilicate nanotube, and (right) a
section of the wall showing the hexagonal aluminosilicate repeat units.
x
Aluminosilicate (AlSiOH)
Nanotubes - R:2.2 nm, L=100 nm
Aluminogermanate (AlGeOH)
Nanotubes - R:3.3 nm, L=20 nm
z
Maillet, P. et al. JACS. 2010, 132, 1208.
 Aluminum hydroxide shell [(OH)3Al2]
 Interior silanol groups [O3SiOH]
 Average length ~ 100 nm
Hu, S. et al. Chem.Eur. J. 2010, 16, 1889.
 Offers a vast range of compositions and dimensions
100 nm
1
MoO3 Nanotubes
R:6 nm
Georgia Institute of Technology
Applications of Single-Walled Metal Oxide Nanotubes
Kang, D.-Y., et al. J. Phys. Chem. C, 2011, 115, 7676.
Functional site
Nanofluidic Membranes
A
Konduri, S., et al. J. Phys. Chem. C, 2008, 112, 15367.
Zang, J., et al. ACS Nano, 2009, 3, 1548.
B
Nanotube
Polymeric matrix
B
Molecular Separations
Nanocables
Kang, D.-Y., et al. ACS Applied Materials & Interfaces, 2012, 4, 965.
Kang, D.-Y., et al. Journal of Membrane Science, 2011, 381, 50.
Zang, J., et al. J. Phys. Chem. Lett., 2010, 1, 1235.
Kuc, A. and T. Heine, Advanced Materials, 2009, 21, 4353.
2
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Synthesis of Single-Walled Metal Oxide Nanotubes
 Low temperatures synthesis (95°C)
 Inexpensive and easily accessible reactants
 Can be obtained in pure form
Al - Aluminum-tri-sec-butoxide (ASB) +
Si - Tetraethyl orthosilicate (TEOS) in HClO4
Freeze-Drying
25°C
95°C
DI H2O
Step 1 - Aging 18 h
3
Step 2 - Heating 96 h
Dialysis 96 h
Pure Form
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Research Objectives
Engineering inorganic nanoscopic objects
Ångstrom Level
Dimensional Control
 Exemplary material – aluminosilicate nanotubes
 Identification of nanointermediates and local structural evolution – Nuclear
Magnetic Resonance (NMR), Electrospray Ionization Mass Spectrometry (ESI-MS)
 Molecular Configuration – solvated Density Functional Theory (DFT) simulations
 Structural characterization at larger scales – Cryo-electron Microscopy, and TEM
4
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Aluminosilicate Speciation During Aging (25˚C) – ESI-MS
 Al1SiX(ClO4)y – Al13Six(ClO4)y (x= 0-7, y= 0-5)
 Complete and incomplete Al6Si ring units
 Speciation is same throughout the aging
m/z 733: [Al12Si7O16(OH)30(H2O)10]2+
m/z 595: [Al10SiO3(OH)22(H2O)4(Cl35O4)3(Cl37O4)]2+
243
x107
ESI(+)
25°C
300
400
500
600
m/z 451: [Al6(OH)17]+
678
697
706
0.0
200
597
207
221
0.2
267
303
323
341
357
385
403
421
433
459
487
515
541
261
0.4
700
800
Chemical Formula of AlSi Species
Peak Series (m/z)
[Al(OH)2(H2O)n]+
[Al(OH)(H2O)n(ClO4)]+
[Al(H2O)n(ClO4)2]+
[Al2(OH)5(H2O)n]+
[Al2(OH)4(ClO4)(H2O)n]+
[Al2SiO2(OH)5(H2O)n+1]+
[Al3SiO2(OH)6(H2O)n(ClO4)]2+
[Al3SiO2(OH)8(H2O)n]+
[Al7Si2O5(OH)13(H2O)n+3(ClO4)3]3+
[Al2(OH)3(H2O)n(ClO4)2]+
[Al7Si2O5(OH)12(H2O)n(Cl35O4)3(Cl37O4)]3+
[Al8Si2O6(OH)13(H2O)n(Cl35O4)3(Cl37O4)]3+
[Al2(OH)2(H2O)n(ClO4)3]+
[Al2(OH)2(H2O)n(Cl35O4)2(Cl37O4)]+
[Al2SiO(OH)5(H2O)n(ClO4)2]+
[Al4SiO3(OH)8(H2O)n+1(ClO4)]+
[Al2SiO(OH)4(H2O)n(ClO4)3]+
[Al5SiO3(OH)12(H2O)n+1]+ / [Al4Si2O4(OH)11(H2O)n+1]+
[Al5Si2O5(OH)12(H2O)n+1]+
[Al6SiO3(OH)15(H2O)n]+
[Al4Si2O4(OH)10(H2O)n(ClO4)]+
[Al10SiO3(OH)22(H2O)n(ClO4)3(ClO4)]2+
[Al8Si2O5(OH)15(H2O)n+5(Cl35O4)4(Cl37O4)]2+
[Al10Si3O9(OH)18(H2O)n+1(Cl35O4)3(Cl37O4)]2+
[Al12Si3O9(OH)27(H2O)n+6(Cl35O4)]2+
[Al12Si3O9(OH)25(H2O)n(Cl35O4)2(Cl37O4)]2+
[Al13Si2O10(OH)22(H2O)n+1(Cl35O4)2(Cl37O4)]2+
[Al12Si3O9(OH)26(H2O)n+1(ClO4)2]2+
[Al12Si5O12(OH)29(H2O)n+3(ClO4)]2+
[Al13O4(OH)24(H2O)n+2(Cl35O4)4(Cl37O4)]2+
[Al12Si4O10(OH)29(H2O)n+6(Cl35O4)]2+
[Al12Si7O16(OH)30(H2O)n+5]2+
[Al12Si4O10(OH)28(H2O)n+8(Cl35O4)2]2+
[Al13Si4O16(OH)18(H2O)n+5(Cl35O4)2(Cl37O4)]2+
[Al12Si7O13(OH)35(H2O)n+5(ClO4)]2+
[Al13Si6O10(OH)40(H2O)n+3(ClO4)]2+
61+18n (n=0-2)
143+18n (n=0-3)
225+18n (n=0-3)
139+18n (n=0-2)
221+18n (n=0-3)
217+18n (n=0-3)
171+9n (n=0-5)
277+18n (n=0-2)
299+6n (n=0-4)
303+18n (n=0-5)
309+6n (n=0-10)
329+6n (n=0-7)
385+18n (n=0-4)
387+18n (n=0-4)
381+18n (n=0-3)
437+18n (n=0-2)
463+18n (n=0-4)
433+18n (n=0-6)
493+18n (n=0-3)
493+18n (n=0-3)
497+18n (n=0-4)
559+9n (n=0-4)
597+9n (n=0-4)
610+9n (n=0-5)
609+9n (n=0-4)
638+9n (n=0-6)
638+9n (n=0-6)
605+9n (n=0-7)
678+9n (n=0-4)
678+9n (n=0-4)
648+9n (n=0-4)
688+9n (n=0-5)
707+9n (n=0-4)
707+9n (n=0-4)
756+9n (n=0-3)
756+9n (n=0-3)
m/z
5
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Aluminosilicate Speciation During Aging (95˚C) – ESI-MS
x107
0.10
239
257
95°C
277
0.05
0.00
200
Al8Six(ClO4)y-Al13Six(ClO4)y
300
400
500
m/z




6
600
700
800
Chemical Formula of AlSi Species
Peak Series m/z
[Al(OH)2(H2O)n]+
[Al(OH)(H2O)n(ClO4)]+
[Al(H2O)n(ClO4)2]+
[Al2(OH)5(H2O)n]+
[Al2(OH)4(ClO4)(H2O)n]+
[Al2SiO2(OH)5(H2O)n+1]+
[Al3SiO2(OH)6(H2O)n(ClO4)]2+
[Al3SiO2(OH)8(H2O)n]+
[Al7Si2O5(OH)13(H2O)n+3(ClO4)3]3+
[Al2(OH)3(H2O)n(ClO4)2]+
[Al7Si2O5(OH)12(H2O)n(Cl35O4)3(Cl37O4)]3+
[Al2(OH)2(H2O)n(ClO4)3]+
[Al2(OH)2(H2O)n(Cl35O4)2(Cl37O4)]+
[Al2SiO(OH)5(H2O)n(ClO4)2]+
[Al4SiO3(OH)8(H2O)n+1(ClO4)]+
[Al2SiO(OH)4(H2O)n(ClO4)3]+
[Al5SiO3(OH)12(H2O)n+1]+
[Al5Si2O5(OH)12(H2O)n+1]+
[Al6SiO3(OH)15(H2O)n]+
[Al4Si2O4(OH)10(H2O)n(ClO4)]+
[Al3SiO2(OH)7(H2O)n+6]2+
[Al3SiO2(OH)5(H2O)n+6(ClO4)2]2+
[Al3SiO2(OH)8(H2O)n+2]+
61+18n (n=0-2)
143+18n (n=0-3)
225+18n (n=0-3)
139+18n (n=0-2)
221+18n (n=0-3)
217+18n (n=0-3)
171+9n (n=0-5)
277+18n (n=0-2)
299+6n (n=0-4)
303+18n (n=0-5)
309+6n (n=0-10)
385+18n (n=0-4)
387+18n (n=0-4)
381+18n (n=0-3)
437+18n (n=0-2)
463+18n (n=0-4)
433+18n (n=0-6)
493+18n (n=0-3)
493+18n (n=0-3)
497+18n (n=0-4)
184+9n (n=0-1)
266+9n (n=0-1)
313+18n (n=0-2)
Al1SiX(ClO4)y – Al7Six(ClO4)y (x= 0-2, y= 0-3)
Nanotube-like intermediates (m/z 500-800) disappear from ESI-MS spectra
Abrupt pH drop from 3.3 to 1.7 upon heating to 95 ˚C
Condensation of curved nano-intermediates takes place
Georgia Institute of Technology
27Al
Liquid-State NMR
Nanotube-like Hexa-coordination
6 ppm
 Keggin cluster Al-13 (63.3 ppm, 12 ppm)
 Hexa-coordinated monomer Al-1 (0 ppm)
 Nanotube-like hexa-coordination (~6 ppm)
(b)
e.g. 18h Aging
[AlO4Al12(OH)24(H2O)12]7+
Keggin cluster Al-13
Monomer
27Al-Chemical-Shift
(ppm)
 Nanotube-like and Keggin species
 Chemical shift, linewidth and integrated
areas of each peak are examined
7
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27Al
Liquid-State NMR
 Area of NMR resonances — concentration in solution
Aging Stage at 25˚C
 FWHM (full width at half maximum)
—environmental ordering around Al
Heating Stage at 95˚C
 Chemical shift — structure
Heating Stage at 95˚C
Aging Stage at 25˚C
8
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Overall Mechanism of Nanotube Formation
Heating Stage at 95˚C
Aging Stage at 25˚C
Formation of Single-Walled Aluminosilicate Nanotubes from
Molecular Precursors and Curved Nanoscale Intermediates
Yucelen, G. I., Choudhury, R. P., A. Vyalikh, A. Scheler, U, Beckham, H. W. and Nair, S. "Formation of Single-Walled
Aluminosilicate Nanotubes from Molecular Precursors and Curved Nanoscale Intermediates", Journal of the American
Chemical Society, 2011. 133(14): p. 5397-5412.
9
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Shaping Single-Walled Metal Oxide Nanotubes
 Hypothesis – a relationship between the precursor shape and the resulting nanotube
 Can we achieve Ångstrom-level control over precursor and nanotube curvature?
 Binding of ligands such as perchlorate (ClO4-), chloride (Cl-), and acetate (CH3COO-)
Initial Precursors
Ligands
10
Cl-
ClO4-
CH3COO-
Ångstrom-level Curvature Control
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XRD, Nitrogen Physisorption, and NMR
1
2
Experimental XRD patterns
0.80±0.02 nm
0.05 M HCl
0.93±0.05 nm
0.05 M 50%HCl-50%HClO4
0.99±0.06 nm
0.05 M HClO4
Pore Diameters – N2 Physisorption Studies
3
CH3COOH
HCl
50%HCl-50%HClO4
HClO4
27Al
11
 Experimental results support the hypothesis
 Largest external diameters obtained by ClO4 Nanotube composition is preserved
and 29Si MAS NMR
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Cryo-Electron Microscopy
 Nanotube diameters are measured from high-resolution cryo-EM micrographs
 Nanotube diameter was determined based on measurement of 50 nanotubes
 Largest diameters obtained by the use of HClO4, smallest by the use of CH3COOH
Theoretical Line
Measured Diameter
2.8
CH3COOH
R: 2.2±0.2 nm
HCl+HClO4
R: 2.5±0.2 nm
HCl
R: 2.4±0.2 nm
HClO4
R: 2.8±0.2 nm
External Diameter (nm)
2.7
2.6
2.5
2.4
2.3
2.2
2.1
CH3COOH
11
HCl
12
HClO4 + HCl
13
14
HClO4
15
# of Repeat Units in Circumference
Ångstrom-level Diameter Control
12
Georgia Institute of Technology
Curvatures of DFT-optimized nanoscale intermediates
R = 2.3 ± 0.1 nm
R = 1.4 ± 0.1 nm
κ = 1/R = 0.44 nm-1
HClO4
κ = 1/R = 0.71 nm-1
[Al10SiO3(OH)22(H2O)4(ClO4)4]2+
[Al10SiO3(OH)26(H2O)4]2+
HCl
R = 1.4 ± 0 nm
κ = 1/R = 0.71 nm-1
R = 1.5 ± 0 nm
κ = 1/R = 0.66 nm-1
CH3COOH
[Al9Si2O6(OH)17(H2O)3Cl3]3+
R = 0.73 ± 0.08 nm
R = 0.7 ± 0 nm
κ = 1/R = 1.37 nm-1
κ = 1/R = 1.4 nm-1
[Al10Si2O6(OH)19(H2O)6(CH3COO)5]2+
13
[Al9Si2O6(OH)20(H2O)3]3+
[Al10Si2O6(OH)24(H2O)4]2+
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Shaping Single-Walled Metal Oxide Nanotubes
 There is a clear correlation between the precursor curvatures and the diameters of
the nanotubes obtained.
 The precursor curvatures follow the trend of HClO4<HCl<CH3COOH, and the
nanotube diameters correspondingly follow the inverse trend HClO4>HCl>CH3COOH
Yucelen, G.I., Kang, D-Y, Guerrero-Ferreira, R. C., Wright, E. R., Beckham, H. W. and Nair, S., “Shaping Single-Walled Metal
Oxide Nanotubes from Precursors of Controlled Curvature”, Nano Letters, 2012. 12(2): p. 827-832.
14
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Modelling Nanotube Formation and Growth Mechanisms
Quantitative kinetic model formulation:
k1
nP 
→ A → NTi =
(i a=
, a n / 4)
k1
k2
k3
NTi + P 
→ NTi +1
(i ≥ a, a + 1, a + 2,..., N )
NTi + NT j → NTi + j
k4
(i, j ≥ a, a + 1, a + 2,..., N )
P
NT
A
k3
d [P ]
m
= −nk1 [P ] − k3 [P ][NT ]
dt
d [A]
m
= k1 [P ] − k 2 [A]
dt
d [NT ]
2
= k 2 [A] − k 4 [NT ]
dt
d [NT ]i
= k 2 [A] − k3 [P ]NTi − k 4 NTi [NT ] (i = a )
dt


N

d [NT ]k
1  i = k −1
= k3 [P ][NTk −1 − NTk ] + k 4  ∑ NTi NT j − 2 NTk ∑ NTi 
dt
2  i =a
i =a

 j = k −i

k2
k4
(k > a)
 Three primary type of species coexist in synthesis solutions: P, A, and NT
 Nanotube synthesis and growth is assumed to be a four-step process
15
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Model Fitting and Validation
(a)
(b)
8h
(c)
14 h
30 h
(e)
(g)
85 h
t = 30 h
t = 14 h
1
0.8
0.8
0.8
0.8
0.4
0.2
0
0
0.6
0.4
400
600
0
0
800
0.6
0.4
0.2
0.2
200
[NTi] (normalized)
1
[NTi] (normalized)
1
0.6
200
L (nm)
t = 72 h
400
600
L (nm)
t = 85 h
1
0
0
800
0.4
0.2
200
400
600
0
0
800
0.8
0.8
0.2
0
0
0.2
200
400
L (nm)
600
800
0
0
[NTi] (normalized)
0.8
[NTi] (normalized)
0.8
[NTi] (normalized)
1
0.4
0.6
0.4
400
L (nm)
600
800
1.4×107
k2 (s-1)
2.2×10-4
k3 (M-1s-1)
2.8×102
k4 (M-1s-1)
19.4
n
80
m
3.9
P0 (M)
8.0×10-5
0
0
600
800
600
800
0.6
 Dimensional
evolution
is
studied by TEM
 Model captures all features of
the NDLs (~10% avg. error)
0.4
0.2
0.2
200
400
L (nm)
t = 144 h
1
0.4
200
L (nm)
t = 96 h
1
0.6
k1 (M-ms-1)
0.6
1
0.6
AlSiOH NT Synthesis
t = 48 h
1
[NTi] (normalized)
[NTi] (normalized)
144 h
Reaction Constants
Simulated NLD
Experimental NLD
[NTi] (normalized)
(h)
96 h
t=8h
16
48 h
(f)
72 h
(d)
200
400
L (nm)
600
800
0
0
200
400
L (nm)
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Model Predictions
 The model is able to predict NLDs and mean lengths of nanotubes when P0 is
increased and decreased by 50 percent
96 h
t = 96 h
1
1
0.5P(b)
0
0.6
0.4
400
0.4
600
0
0
800
200
1
1.5P(d)
0
[NTi] (normalized)
t
0.6
0.4
0
0
600
800
1.5P(c)0
240
0.5 P
220
0
P
200
0
180
1.5 P
160
0
140
120
100
80
20
40
60
80
100
120
140
Synthesis Time (h)
0.8
96 h
0.8
400
Lt =(nm)
96 h
tL=(nm)
14 h
1
[NTi] (normalized)
Experimental NLD
200
0.2
0.5P0 , t=96 h
0.6
1.5P0 , t=96 h
0.4
0.2
200
400
L (nm)
17
0.6
0.2
0.2
0
0
0
0.8
[NTi] (normalized)
t 85 h
[NTi] (normalized)
Simulated NLD
0.8
0.5P(a)
Average AlSiOH Nanotube Length (nm)
t
t = 14 h
600
800
0
0
200
400
600
80
L (nm)
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Thank You!!!
POROUS MATERIALS AND MEMBRANES via
NANOSCALE PROCESSING STRATEGIES
Nair Research Group
Beckham Research Group
ACKNOWLEDGMENTS:
This work was supported by The National Science Foundation (CAREER, CBET-0846586)
COLLABORATORS:
Prof. E. R. Wright (The Robert P. Apkarian Integrated Electron Microscopy Core of Emory University)
Prof. F. Fernandez (Chemistry & Biochemistry, Georgia Tech)
Dr. J. Leisen (Parker H. Petit Institute of Bioengineering and Biosciences, Georgia Tech)
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