2 Emulsified Solution TsoFu Mark Chang 12 Wei Hao Lin 13 ChunYi Chen 12 YungJung Hsu 3 Masato Sone 12 1 Institute of Innovative Research Tokyo Institute of ID: 562188
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Slide1
Effect of Pressure on Crystal Structure of Metal Oxides Formed in Supercritical CO2 Emulsified Solution
Tso-Fu
Mark Chang1,2,*, Wei-Hao Lin1,3, Chun-Yi Chen 1,2, Yung-Jung Hsu3, Masato Sone1,21Institute of Innovative Research, Tokyo Institute of Technology2CREST, Japan Science and Technology Agency3Department of Materials Science and Engineering, National Chiao Tung UniversitySlide2
Tokyo Tech
Founded in 1881
2Suzukakedai CampusSlide3
Outline
Purposes of the studyWhy metal oxides: TiO2 and
ZnOWhy electrodepositionWhat is supercritical fluidWhy supercritical CO2 (sc-CO2) CharacterizationTiO2ZnOSlide4
Why TiO2 or ZnO
Wastewater Treatment
TiO2: Degradation of organic compounds [1]ZnO: Removal of biological nitrogen and phosphorus [2]FilterTiO2: Bioaerosols [3]ZnO: Aerosols [4]Factors affecting the performanceMorphology: particle size, porosity, surface areaPhotocatalytic activity: crystal structureA.
Haarstrick , O.M. Kut , and E. Heinzle,
Environ. Sci.
Technol
.
30
(1996) 817–824.
X.
Zheng,
R.
Wu, and
Y. Chen,
Environ
.
Sci
.
Technol
.,
45 (2011), 2826–2832.C.-Y. Lin and C.-S. Li, Aerosol Sci. Technol., 37 (2003) 162–170.Y.C. KANG and S.B. PARK, J. Mater. Sci. Lett., 16 (1997) 131–133.
4Slide5
V
Counter Electrode,
Anode:
Pt Powersupply
Electrodeposition
Oxidation: Giving e
―
2H
2
O → O
2
+ 4H
+
+ 4e
―
Reduction: Getting e
―
Ni
2+
+ 2e― → NiNiCl2 and/or NiSO4
e
―
Ni layer
5
Working Electrode,
Cathode: Cu
Low cost
VersatileSlide6
Supercritical Fluid
Phase diagram of a single substance
6
Critical Point
Triple Point
Gaseous Phase
Solid Phase
Liquid Phase
Supercritical FluidSlide7
Supercritical Fluid
Disappearance of the meniscus at the critical point
7Slide8
Supercritical Fluid
Property
Density (kg/m3 )Viscosity (cP)Diffusivity (mm2 /s) Gas 1 0.01 1-10 SCF100-8000.05-0.1 0.01-0.1
Liquid 1000 0.5-1.0 0.001
FluidCritical Temperature (K)Critical Pressure (bar)
Carbon
dioxide
304.1
73.8
Ammonia
405.5
113.5
Water
647.3
221.2
n-Pentane
469.7
33.7
Toluene
591.8
41.0Comparison of physical and transport properties of gases, liquids, and SCFs[1]Critical Conditions for Various Supercritical Solvents[1]8
Edit
Székely
, Supercritical Fluid Extraction, Budapest University of Technology and EconomicSlide9
Electrochemistry with Sc-CO
2
LimitationsLowLowSolutions
M+
M
+
M
+
e
−
Sc-CO
2
e
−
Polar
Entrainer
Surfactant
or
Electrolyte
metal salt solubility
electrical conductivity
9Slide10
CO
2
-Continuous Dispersions
H
2
O
CO
2
CO
2
-philic tail
Hydrophilic head
Water in C
O
2
Emulsion
10Slide11
Water-Continuous Dispersions
CO
2
Water
Hydrophobic tail
Hydrophilic head
CO
2
in Water Emulsion
11Slide12
Water-Continuous Dispersions
Water-continuous dispersionsHydrocarbon surfactantIonic:
CH3(CH2)11OSO3Na[1] Nonionic: (H(OCH2CH2)8(CH2)12H[2] Fluorocarbon surfactant: CF3-(O-CF2-CF(CF3))n-(O-CF2)-COO-NH4+,[3]
J.D. Oates and R.S. Schechter, Journal of Colloid Interface Science, 131
(1989) 307-319.H. Wakabayashi et al., Surface Coatings & Technology,
190
(2005) 200-205.
C.T. Lee et al.,
Langmuir
,
15
, (1999) 6781−6791.
C/W emulsion
12Slide13
Ni Electroplating with Sc-CO2 Emulsion
Morphology control[
1,2]Grain refinement and hardness improvement[3]CONVESCEEP-SCE
H. Wakabayashi et al., Surface Coatings & Technology,
190 (2005) 200-205.Md.Z. Rahman et al., Surface Coatings & Technology
,
201
(2006) 7513-7518.
S.T. Chung and W.T. Tsai,
Journal of the Electrochemical Society
,
156
(2009) D457-D461.
CONV
EP-SCE
Grain size (nm)
Microhardness
(
Hv
)
CONV43446 ± 21CONV at 10 MPa45412 ± 16EP-SCE at 10 MPa14736 ± 2313Slide14
Cathodic Deposition of TiO2
C.C.Huang
et al. ,
Electrochim
.
Acta
55
(2010) 7028
Cathodically
deposited TiO
2
[1]
14Slide15
Experimental Apparatus
(a) CO
2 gas tank, (b) CO2 liquidization unit, (c) liquidization pump, (d) high-pressure pump, (e) thermal bath, (f) reaction cell, with PEEK coating on the inner wall, (g) substrates, (h) stirrer, (i) programmable power supply, (j) back pressure regulator, (k) trap, (l) thermometer.
`
15Slide16
TiO2 Morphology & Crystal Structure
Figure 1.
SEM image of TiO2 structures prepared by (a) conventional process (b) deposition with surfactants (c) deposition with sc-CO2 emulsion.
16(a) CONV
(b) CONV with surf(c) With sc-CO2
T.F.M. Chang
et al. ,
Electrochem
.
Commun
.,
33
(2013)
68.Slide17
TiO2 Crystal Structure
5 nm
17
T.F.M. Chang
et al. ,
Electrochem
.
Commun
.,
33
(2013)
68.Slide18
TiO
2
Crystal Structure
Cathode
TiCl
3
+NaNO
3
electrolyte
Bulk
Diffusion
Layer
Deposited
TiO
(OH)
2
Layer
Pores formed by gas evolution
18Slide19
Film
TiO
2
Crystal Structure
Cathode
Deposited
TiO
(OH)
2
Layer
Sc-CO
2
Dispersed Phase
TiO
2
grain size
∝
production
19Slide20
ZnO Morphology
20
W.H. Lin et al. , J. Phys. Chem. C, 117 (2013) 25596.(a) Conv. Dep.(b)Conv. with Surf
(c) Dep. with sc-CO2Slide21
ZnO Mesocrystal
21
W.H. Lin et al. , J. Phys. Chem. C, 117 (2013) 25596.Slide22
ZnO Light Absorption Ability
22
W.H. Lin et al. , J. Phys. Chem. C, 117 (2013) 25596-25603.
ZnO mesocrystal gave slower PL decay
ZnO mesocrystal has high crystallinity and less structural defectSlide23
ZnO Photocatalytic Activity
23
W.H. Lin et al. , J. Phys. Chem. C, 117 (2013) 25596.Slide24
Conclusions
Supercritical CO2 emulsified Electrolyte
is effective in controlling morphology and crystal structure of the TiO2 and ZnO depostied. TiO2Improved crystallinityZnOMesocrystalImproved photocatalytic activity24Slide25
Japan side:PeopleProf. Masato
Sone of Tokyo Institute of TechnologyProf. Chun-Yi Chen of Tokyo Institute of Technology
Funding2016 Tokuyama Science Foundation Traveling GrantNext Generation World-leading Researchers (NEXT Program) GN037, Cabinet Office (CAO), JapanCREST Project operated by the Japan Science and Technology Agency (JST)Taiwan side:PeopleProf. Yung-Jung HsuPhD candidate Wei-Hao LinFundingNational Science Council of Taiwan (NSC-101-2213-M-009-018)Acknowledgement25Slide26
Thank You For Your Attention
26Slide27
Challenges of Aqueous Solutions in Nanotechnology
Representation of the contracting surface forces in pores of
different size during drying[1]
Horizontal component
Vertical component
Damage pore structure (
nano-sacle
)
Demote transport efficiency
liquid
N.
Husing
and U. Schubert,
Angew
. Chem. Int. Ed.
,
37
(1998) 22.
27Slide28
High hydrogen solubility (non-polar)
Low surface tension (technically zero)
H2Merits of Sc-CO2 in Electroplating
Cathode
Defect !!!
Electrochemistry + Aqueous Electrolyte
Desorption
Enhancement
Sc-CO
2
Plated Film
2 H
+
+ 2 e
−
↔ H
2
(g)
28Slide29
ZnO Exp Conditions
CO2 with a minimum purity of
99.99% was used. 5 mM Zn(NO3)2, 235 mM NaCl, 45 mM NaNO3 and 2mM NaHCO3A non-ionic surfactant, polyoxyethylene lauryl ether (C12H25(OCH2CH2)15OH) was usedAl plates with dimensions of 1.0X2.0 cm2 were used as the working electrode at cathode. Pt plates with dimensions of 1.0X2.0 cm2 were used as the counter electrode at anode. 20 vol% of CO2 and 0.08 vol% of the surfactant with respect to total volume of the reaction chamber were used. Cathodic current density of 0.15 A/dm2, temperature of 70˚C for 10 min10 MPa
29Slide30
Results & Discussion: ZnO
30