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Effect of Pressure on Crystal Structure of Metal Oxides For Effect of Pressure on Crystal Structure of Metal Oxides For

Effect of Pressure on Crystal Structure of Metal Oxides For - PowerPoint Presentation

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Effect of Pressure on Crystal Structure of Metal Oxides For - PPT Presentation

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

supercritical zno structure co2 zno supercritical co2 structure tio2 crystal science technology 2013 water conv surface lin phase amp

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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