1. TEMPLATED SYNTHESIS OF
NANOPOROUS TITANIA/NANO-
CARBON COMPOSITES
Jayur Mistry
Graduate Student (Dan F. Smith Dept. of Chemical Engineering)
Thesis Presentation
1st August 2016
5. WHY NANOCOMPOSITES?
• Enhanced electrical and mechanical properties
• Chemical resistance & thermal conductivity
• Stable at very high temperatures and pressures
• Can be customized by altering materials giving different properties
6. NANO-POROUS TITANIA/NANO-
CARBON COMPOSITES
• A nano-composite material
comprising of porous titania
(TiO2) synthesized from the
soft templates, organized
with hexagonal symmetry
and nano-carbons (i.e.
MWCNT and GO)
• Since the composites have a
large surface area due to its
porous micro structure, it
finds many applications in
heterogeneous catalysis,
electronics, and sensors.
7. TITANIA
• Titanium dioxide or Titania (TiO2) is
a white solid inorganic substance,
thermally stable, non-flammable,
and poorly soluble.
• Conventionally used as a white
pigment, paints and sunscreens,
heterogeneous catalysis, gas
sensors, protective coating and
electronics.
• Occurs in nature as the well-known
minerals, rutile, anatase and
brookite.
Diebold, U. The Surface Science of Titanium Dioxide. Surface Science
Reports 2003, 48, 53–229.
8. NANO-CARBON
• Nanocarbons are Carbon based
materials that can be bonded at the
molecular level in differing ways to
achieve unique properties.
• Here, we have used multi walled carbon
nanotubes (MWCNT) and Graphene
Oxide (GO) separately.
Graphene oxide
Multi walled carbon nanotube
9. TEMPLATED SYNTHESIS
• What is a template?
A shaped piece of material
used as a patterns for
different processes.
• Why templated synthesis?
To synthesize titania (TiO2)
with a specific
microstructure (i.e.
honeycomb) results having
very high surface area.
http://what-when-how.com/nanoscience-and-
nanotechnology/electrically-conducting-polymeric-nanostructures-
techniques-for-one-dimensional-synthesis-nanotechnology/
http://research.chem.psu.edu/axsgroup/Ran/research/templat
esynthesis.html
10. MATERIALS
• Isooctane (2,2,4-trimethylpentane)
• Dioctyl sulfosuccinate sodium salt (AOT)
• Titanium iso-propoxide (TIP) precursor
• Lecithin (L-a phosphatidylcholine, 95%
Soy)
• Multi wall carbon nanotubes (MWCNT)
• Graphene Oxide (GO)
L-a phosphatidylcholine
Titanium iso-propoxide
Dioctyl sulfosuccinate sodium salt
12. EXPERIMENTAL PROCEDURE
• Porous titania synthesis
TIP is added in a 1:1 volume ratio with isooctane
to the solution of isooctane/AOT (0.8
M)/Lecithin (0.4 M).
A calculated amount of water, corresponding to
the desired W0 (the ratio of moles of water to
AOT), is added to this solution and mixed using
a vortex mixer.
Immediately after water addition, a white
precipitate is observed indicating TiO2
formation.
The samples are dried at 60 °C for 24 h and
calcined by ramping the temperature in
increments of 50 °C every 30 min, starting at
400°C and going to 550 °C. The sample is left at
550 °C for 4.5 h to obtain a white powder.
The calcination step eliminates the trace
amounts of surfactants left after solvent
removal.
13. EXPERIMENTAL PROCEDURE
• Nanoporous Titania/Nano-
carbon Composite Synthesis
Nano-carbon (MWCNT or GO) is
sonicated in the water with the
concentration of 0.025 gm/l to
obtain better dispersion and
added to the
TIP/isooctane/lecithin/AOT to
reach a desired W0.
This gives the same color as pure
titania with some visible black (in
case of MWCNT) or brown
particles (in case of GO).
The drying and calcination steps
remain the same as used for the
support synthesis.
+nanocarbons
15. SURFACTANT TEMPLATE MECHANISM
• The addition of lecithin to
AOT water-in-oil (isooctane)
micro emulsions leads to
the formation of a rigid gel
as the water content (W0) is
increased above a specific
threshold.
• This system is a gel-like
crystalline phase where the
microstructure evolves from
reverse hexagonal to
lamellar with increasing
water content and/or
temperature.
Hexagonal
Lamellar
17. SAMPLES COMPOSITIONS ACCORDING TO W0
W0 H2O (g) αw αs αo Φw Φs Φo
0 0 0 0.502 0.495 0 0.240 0.760
10 0.765 0.099 0.452 0.448 0.104 0.215 0.680
30 2.295 0.249 0.377 0.374 0.259 0.178 0.563
50 3.825 0.365 0.323 0.321 0.368 0.153 0.480
70 5.355 0.436 0.283 0.281 0.456 0.131 0.413
90 6.885 0.498 0.252 0.250 0.515 0.118 0.373
110 8.415 0.584 0.227 0.225 0.584 0.106 0.337
130 9.0945 0.589 0.206 0.204 0.602 0.096 0.302
150 11.475 0.623 0.189 0.187 0.636 0.087 0.276
170 13.005 0.652 0.175 0.173 0.665 0.081 0.255
• W0
the concentration ratio of
water to AOT in the system
(W0 ) [H2O]/[AOT]
αw, αs, and αo denote the
weight fractions of the
aqueous phase, the surfactant
(AOT and lecithin together),
and the oil phase, respectively.
Φw, Φs, and Φo denote the
corresponding volume
fractions..
Liu, L.; Tan, G.; McPherson, G.; John, V. T.; Maskos, K.; Bose, A. High-Resolution NMR
Characterization of a Gel-like Surfactant Mesophase. Langmuir 2008, 24, 9286–9294.
18. • Plot of W0 vs Temperature
demonstrating the effect on
the structure of the
templates.
Liu, L.; Tan, G.; McPherson, G.; John, V. T.; Maskos, K.; Bose, A. High-Resolution NMR
Characterization of a Gel-like Surfactant Mesophase. Langmuir 2008, 24, 9286–9294.
21. XRD RESULTS
MWCNT
TiO2 (W0 = 70)
GO
TiO2+MWCNT (W0 = 70)
TiO2+GO (W0 = 70)
• Diffraction peaks at around 25° and 48°
indicates titania (TiO2) in the anatase phase.
• Similar peaks are visible in the composites
showing the same crystalline structure with
additional peaks appearing because of
Nanocarbons.
22. SCANNING ELECTRON
MICROSCOPY (SEM)
• Generates 3D images by scanning the sample with
focused beam of electrons.
• Used to study micro-structure or surface topography
and compositions
https://www.purdue.edu/ehps/rem/rs/sem.htm
27. PORE
DISTRIBUTION
Figure shown above
describes the pore diameter
distribution. which, is from
10-200nm, but centered at
about 90nm which, is
showing the average size of
the pores. There are a
couple of peaks can be
seen past the size of 200nm
which shows the
agglomeration of
nanoparticles forming a
structure like pores.
28. ELECTRICAL PROPERTIES
• Electrical properties are
measure by performing Cyclic
Voltammetry (CV) using
Solartron CellTest potentiostat
system.
• Cyclic Voltammetry (CV)
Produces by cycling potential
over a working electrode and
measuring the resulting current
30. ELECTROCHEMICAL CELL
• The composite material is kept between poly
(vinyl alcohol)/KOH gel electrolyte and then
hooked up to the potentiostat as an anode.
• The cathode, which works as a reference
electrode in the electrochemical cell can be
made up by any conductive metal, where we
have used copper wire.
• Both the electrodes are immersed in 1M KOH
aqueous solution.
31. CV RESULTS
• The figure shows CV
curves obtained at
different ranges and at
the room temperature
• The voltage is swept at a
few different ranges, say
25mV/s, 50mV/s and
100mV/s as shown in the
figure above. The
response above 25mV/s is
different as a small
change in the current can
be seen in the figure.
25mV/s 50mV/s
100mV/s
I vs time @100mV/s
32. CONCLUSION
• The SEM characterization shows the honeycomb structure and the key
feature attained is a very high surface area of the TiO2 support due to
surfactant templated synthesis.
• Pore diameter distribution carried out from the SEM images of titania
supports shows a range of pore diameters from 10-200nm and a
centered peak with average pore diameter of 90nm. A few peaks after
200nm shows the agglomeration of particles over the surface
• The X-ray diffraction analysis reveals that the titania supports in the
composite materials are in anatase phase as the heat treatment was
limited under 550°C. and the presence of carbon in the composites.
• CV curves at different scan rates show the stability of cell at lower value
(i.e. 25mV/s) as the curve is bigger than the others.
33. FUTURE SCOPE:
• TiN is one of the ideal materials for supercapacitors (SCs)
• TiN (titanium nitride) can be produced by annealing titania at 550° C in
presence of ammonia (NH3)
• Can be used by its irreversible electrochemical oxidation during
charging/discharging process.
• Already used in SCs as nanowires, coatings, atomic layer deposition
(ALD).
• TiN made through surfactant templated synthesis may produce better
results.
TiN
35. Dr. Evan K. Wujcik
Advisor
Dr. Ozge Sen
Committee member
Dr. Clayton Jefferys
Committee member
Editor's Notes
, where 0.85MAOT (1.89 g) and 0.42Mlecithin (1.59 g) are dissolved in 5 mL of isooctane.
The X-ray diffractogram shown below, exhibit strong diffraction peaks at around 25° and 48° indicates titania (TiO2) in the anatase phase.8 (As anatase is preferred at temperatures below 550°C.4, 5) The crystalline structure of TiO2/GO and TiO2/MWCNT are investigated and compared with the results of GO and MWCNT. All the (101), (004), (200), (105), (211) (for TiO2/GO), and (204) (for TiO2/MWCNT) diffraction peaks correspond to the anatase phase of TiO2 in the composite materials.42 Results show that the diffraction pattern peak intensity of the titania increases with increasing particles size.32 As we have synthesized nano-particles of titania for support, it shows less intense peaks in the figure shown below.
Basically CV is produces by cycling potential over a working electrode and measuring the resulting current
