panoscopic assembling of ceramic materials for ... tsugio sato institute of multidisciplinary...

1

Tsugio SatoInstitute of Multidisciplinary Research for Advanced Materials,

Tohoku University, Sendai 980-8577, Japan

Symposium on Advanced Composite Materials24 February, 2011

Sendai

Panoscopic Assembling of Ceramic Materials for Environmental Clean-up

and Human Health

2

CONTENTSCONTENTS

Panoscopic Assembling of Ceramic Materials for High Performance Application

Design and Development of Photocatalyst for Environmental Clean-up

Design and Development of Ceria-based Inorganic UV-shielding Materials for Human Health

Conclusion




Conclusion

3




Conclusion




Conclusion

4

Hierarchical morphology control of ceramics from nano to macro

Panoscopic Assembling of CeramicsPanoscopic Assembling of Ceramics

New functional Materials

Nano Micro Meso Bulk

Nano particle1 m

Thin filmComposite Film magnet mortor

High Performance Photocatalyst for Environmental Clean-up&

High Performance Inorganic UV-shielding Materials for Human Health

5




Conclusion




Conclusion

Materials Chemistry to support Sustainable Development of Human Being Society Development of non-fossil energy using processesEfficient use of energiesEffective production of the non-fossil energies

Materials Chemistry to support Sustainable Development of Human Being SocietyDevelopment of non-fossil energy using processesEfficient use of energiesEffective production of the non-fossil energies

Global warming Global warming

Environmental pollutionsEnvironmental pollutions

Drying up of resourcesDrying up of resources

6

Visible light< 3 eV(> 400 nm)

Development of high performance visible light responsive photocatalyst which can use sunlight and/or indoor light

Development of high performance visible light responsive photocatalyst which can use sunlight and/or indoor light

e-

h+

h

O2

O2-

Organics

CO2

Photocatalytic reaction

Self-cleaning of light cover glass in the tunnel of highway (Toshiba Lighting & Technology Co. ）

Antibacterial tile (Toto Co.)

DeNOx catalyst(Environmental clean-up)

Anti-fogging

7

Narrow band gap Visible light use

High specific surface area High contact efficiency

High crystallinity Long life time of electron & hole

F ig . 太陽光の分光エネルギー分布

Wavelength (nm)

E ner

gy (W

m2 /n

m)

3.10 2.07 1.55 1.24 1.03 0.89E (eV)

TiO2

Composite formation

e-

h+

hEg

High crystallinity fine particles of narrow bandgap semiconductors

UV5%

Vis45%

IR50%

Design of high performance visible light responsive photocatalyt Design of high performance visible light responsive photocatalyt

Long life time of electron & hole

Spectra of sun light 8

Solvothermal

Solvent ＋

Thermal

The First International Conference on Solvothermal Reactions (1994, Takamatsu)

Reactions using high temperature and/or high pressure solvents

Reactions using high temperature and/or high pressure solvents

Solvothermal reactionsSolvothermal reactions

9

Ionic product, Kw , changes depending on the solvent, temperature and pressure

Accelerate the acid-base

reaction rate

Proceed the chemical

reactions under mild conditions

10

Dielectric constant changes depending on the

solvent, temperature and

pressure

Control of the nucleation and crystal growth

Fabricate fine crystals with high

crystallinity

11

Control of morphology, crystal growth and agglomeration using appropriate solvent and surface modifiers

（Prof. Ajiri, IMRAM, Tohoku University） 12

Solvothermal reactionsSolvothermal reactions

Proceeding of chemical reactions under milder conditions

Depression of crystal growth and agglomeration

High performance photocatalyst

Nanocrystals with high crystallinity

13

Solvothermal synthesis of titania photocatalystsSolvothermal synthesis of titania photocatalysts

500 cm3 (CH3 )2 CHOH + 0.66 mol Ti[OCH(CH3 )2 ]4

Hydrolysis

in 50 cm3 H2 O -500 cm3 (CH3 )2 CHOH at room temperature

Washing

with 50 vol.-% methanol and methanol

Drying

in a vacuum desiccator at room temperature

TiO2 gel

Solvothermal treatment

0.5 g gel in 6 cm3 solvent (methanol, n-hexane, water)

TiO2 nanocrystal 14

0

2

4

6

8

10

12

14

0 1 2 3 4 5

H2

evol

utio

n (m

mol

)

Time (h)

Anatase crystallized in methanol at 200oC for 3 h

Anatase crystallized in water at 200oC for 3 h

Anatase crystallized by calcination at 400oC for 3 h

Commercial TiO 2 (Degussa P25)

Amorpous TiO 2

Cumulative amounts of hydrogen evolved from 0.25 g samples dispersing in 400 cm3 50 vol% methanol solution at 60oC using 100 W high pressure mercury-arc radiation.

Cumulative amounts of hydrogen evolved from 0.25 g samples dispersing in 400 cm3 50 vol% methanol solution at 60oC using 100 W high pressure mercury-arc radiation.

15

Sample

Liq. N2 ( 77 K )

TunamiExcitation source

Ti:Sapphire laser

Ar ion laser

(Output 375 nm, pulse width 10 ps)

Photon-counting system

Time-resolved emission spectra measurements ( URAS in Tohoku Univ. )

Quartz Cell

TiO2 TiO2 (e- ... h+)

TiO2 + h'

TiO2 + heat

h

= kr/(kr + knr)

= 1/(kr + knr)

kr

knr

(Quantum efficiency)

(Fluorescence lifetime)

16

Am

orph

ous

(Bef

ore

crys

talliz

atio

n)Photocatalytic activity of titania crystallized

under various conditions Photocatalytic activity of titania crystallized

under various conditions

0

1

2

3

4

5

0

1

2

3

0 50 100 150 200 250 300

S. Yin, Y. Inoue, S. Uchida, Y. Fujishiro, T. Sato, J. Mater. Res., 13, 844 (1998).

Specific surface area (m2/g)

Fluo

resc

ence

life

tim

e (n

s)

H2

evol

utio

n ra

te (

mm

ol/h

)

In m

etha

nol

(200

o C, 3

h)

In w

ater

(2

00o C

, 3 h

)

In a

ir (4

00o C

, 3 h

)

Solvothermal synthesisSolvothermal synthesisFine crystals High crystallinity

Fine crystals High crystallinity

Excellent photocatalytic activity

Excellent photocatalytic activity

（E

lect

ron

& h

ole

life

time)

17

Total DOSs of doped TiO2 calculated by FLAPW Total DOSs of doped TiO2 calculated by FLAPW

+

-

~380

nm

e-e-

h+

h+

O 2p

N 2p

Ti 3d

Valence band

Conduction band

UV Visible

hν hν’

Conduction ValenceBand-gap

Ref. R.Asahi et al., Science, 293, 269 (2001)

Schematic illustration of visible light response by nitrogen doping Schematic illustration of visible light response by nitrogen doping

18

Preparation of nitrogen-doped titaniaPreparation of nitrogen-doped titania

Calcination

Solid-gas reaction: Calcining titania in nitrogen and/or ammonia gas atmosphere at 550-600oC

R. Asahi, T. Morikawa, T. Ohwaki, A. Aoki, and Y. Taga: Science, 293, 269 (2001).

Solid-liquid reaction: Treating amorphous hydrous titania with ammonia solution followed by calcination around 400oC

S. Sato: Chem. Phys. Lett., 123, 126 (1986).

Decrease the nitrogen content Decrease the specific surface area

Decrease the photocatalytic activity19

Preparation of nitrogen ion-doped titania nanoparticles by the solvothermal reactions : liquid phase reaction without calcination

Preparation of nitrogen ion-doped titania nanoparticles by the solvothermal reactions : liquid phase reaction without calcination

C6 H12 N4 + 6 H2 O →

6HCHO + 4NH3

TiCl3 →

TiO2-1.5x Nx・nH2 O

Homogeneous precipitation

Hexamethylenetetramine-0.38 M TiCl3 mixed aq. solution

Heat at 90oC for 1 h

Heat at 110-230oC for 1 h

Centrifuge

Wash

Vacuum dry at 60oC overnight

Crystallization

TiO2-1.5x Nx・nH2 O →

TiO2-1.5x Nx + nH2 O

C6 H12 N4 added (M) Final pH0.29 10.86 71.43 9

20

Hexamethylenetetramine（HMT）

Compounds used as nitrogen sourcesMonoethanol amine（MEA)

N

N N

N

H2 N CH2 CH2 OH

HN CH2 CH2 OH CH2 CH2 OH

NCH2 CH2 OH CH2 CH2 OH CH2 CH2 OH

Urea

NH2 -CO-NH2

Diethanol amine（DEA）

Triethanol amine（TEA)

21

XRD patterns of the powders prepared by the homogeneous precipitation-solvothermal process in TiCl3 -hexamethylenetetramine aqueous solutions at 190oC and final pH (a) 1, (b) 7 and (c) 9 for 2 h.

XRD patterns of the powders prepared by the homogeneous precipitation-solvothermal process in TiCl3 -hexamethylenetetramine aqueous solutions at 190oC and final pH (a) 1, (b) 7 and (c) 9 for 2 h.

C6 H12 N4 + 6 H2 O → 6HCHO + 4NH3

Product

pH 1-7: Brookite

pH 9 : Rutile

▼

( a )

( b )

( c )

▼

▼

▼ ▼

20 30 40 50 60 2 (o) CuK

pH 1

pH 7

pH 9

●

●

●

●● ● ●

●●●● ●

●

Rutile

BrookiteTiO2 (Degussa P25) Product at pH 7

22

XRD patterns of nitrogen doped TiO2 powders prepared in TiCl3 -hexamethylenetetramine-methanol aqueous solution. XRD patterns of nitrogen doped TiO2 powders prepared in TiCl3 -hexamethylenetetramine-methanol aqueous solution.

20 25 30 35 40 45 50 55 60

CuKθ(deg)

pH 1

pH 7

pH 9

▽ ▽ ▽

■ anatase

▽ rutile

○ brookite

23

Formation of single phases of anatase, rutile & brookite type TiO2-x Ny

Brookite

Rutile

Anatase

S.Yin et . al., J. Mater. Chem.,15, 674-682, (2005)

200 400 600 800 1000 1200

Inte

nsity

Raman Shift /cm-1

Brookite

Rutile

Anatase

t

t

t

Raman

▼ ▼

▼

XPS

392394396398400402404406408

Inte

nsity

/ a.

u.

Binder Energy / eV

N1s

N-Ti

N-NN-CN-O

Brookite

Anatase

Rutile

P-25

Binding energy / eV

Water at pH 9(Rutile)

Methanol at pH 9 (Anatase)

Water at pH 7 (Brookite)

Raman and XPS spectra of nitrogen-doped titania prepared by solvothermal reactions under various conditions Raman and XPS spectra of nitrogen-doped titania prepared by solvothermal reactions under various conditions 24

TEM photographs of the powders prepared in TiCl3 -HMT aqueous solutions and TiCl3 -HMT methanol solution at pH 1, 7 and pH 9 and 190oC for 2 h. TEM photographs of the powders prepared in TiCl3 -HMT aqueous solutions and TiCl3 -HMT methanol solution at pH 1, 7 and pH 9 and 190oC for 2 h.

TiCl3 - HMT - water

TiCl3 - HMT- methanol

S. Yin, etc., J. Mater. Chem., 15, 674 (2005).Effect of pH value & solventsEffect of pH value & solvents

25

0

20

40

60

80

100

200 300 400 500 600 700

P25Brookite (pH7, water)Rutile (pH9, water)Anatase (pH9, methanol)

Wavelength (nm)

Diffuse reflectance spectra of titania powders prepared by solvothermal reactions followed by calcination in air at 400oC for 1h Diffuse reflectance spectra of titania powders prepared by solvothermal reactions followed by calcination in air at 400oC for 1h

N-DopingTiO2

~380

nm

e-e-

h+

h+

O 2p

N 2p

Ti 3d

Valence band

Conduction band

UV Visible

hν hν’

26

Photocatalytic Reaction Apparatus

for NO Destruction

E, > 510nm

F, > 410nm

A B C

D

GH

I

K, NO gas

L, Air

N

NOx

R

on

Yanaco ELC-88A

165mm

P

M

O

J

Q

NO + 3/4 O2 + 1/2 H2 O →

HNO3

Reactor volume: 373 cm3

Flow gas: 1 ppm NOFlow rate: 200cm3/minResidence time: 1.87 minCatalyst: 20×16×0.5 mm3

Light: 450 W high pressure Hg lamp

27

Photocatalytic reaction apparatus for the oxidative decomposition of nitrogen monoxide

Wavelength distributions of LED light used(a) Red light LED (627 nm)(b) Green light LED (530 nm)(c) Blue light LED (445 nm(d) UV light LED (395 nm)

0

50

100

150

200

250

200 300 400 500 600 700 800 900

Wavelength / nm

Inte

nsity

/a.u

.

(d)395 nm

(c) 445 nm

(b)530 nm

(a) 627 nm

28

Photocatalytic activities of different crystalline phases of nitrogen-doped titania for the oxidative decomposition of NO Photocatalytic activities of different crystalline phases of nitrogen-doped titania for the oxidative decomposition of NO

Phtocatalytic activity: Anatase > Brookite > Rutile

P25

Rutile

Brookite

Anatase

0

20

40

60

80

100

0 5 10 15 20 25 30

P25Brookite (pH 7, water)Rutile (pH 9, water)Anatase (pH 9, methanol)

Time / min

> 510 nm > 400 nm > 290 nm

NO

rem

aine

d / %

29

0

20

40

60

80

100

P25WaterMethanolEthanol1-Propanol1-Buthanol

Wavelength / nm

> 510 nm > 400 nm > 290 nm

NO

oxi

dize

d / %

Photocatalytic activity of nitrogen doped titania prepared in various solvents for the oxidative decomposition of nitrogen monoxide under irradiating 450 W high pressure mercury arc filtered with various cut filters. Initial NO concentration: 1 ppm.

Photocatalytic activity of nitrogen doped titania prepared in various solvents for the oxidative decomposition of nitrogen monoxide under irradiating 450 W high pressure mercury arc filtered with various cut filters. Initial NO concentration: 1 ppm.

30

Relationship between the nitrogen content and photocatalytic activity of nitrogen doped titania prepared in various solvothermal conditions. Initital NO concentration: 1 ppm, Irradiation light: 450 W high pressure mercury arc filtered with (a) 290 and (b) 510 nm cut filters.

Relationship between the nitrogen content and photocatalytic activity of nitrogen doped titania prepared in various solvothermal conditions. Initital NO concentration: 1 ppm, Irradiation light: 450 W high pressure mercury arc filtered with (a) 290 and (b) 510 nm cut filters.

0

20

40

60

80

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

N content / wt%

(b) > 510 nmNO

oxid

ized

/wt%

(a) > 290 nm

31

Anion defect in Nitrogen doped TiO2 Anion defect in Nitrogen doped TiO2

Ti(O2-)2x (N3-)x□x/2

Positive effect: Increase the visible light absorption ability

Optimum nitrogen doping content

Negative effect: Formation of anion defect which becomes the electron-hole recombination center

Decrease the lattice defect

Improve the photocatalytic performance

32

Improvement of photocatalytic activity by decreasing the lattice defect

•Co-doping of nitrogen ion and higher valence metal ion

(Ti4+ 1-x Nb5+

x )(O2- 2-x N3-

x )

•Co-doping of nitrogen ion and lower valence anion

Ti(O2- 2x N3+

x F- x )

Improvement of photocatalytic activity by decreasing the lattice defect

•Co-doping of nitrogen ion and higher valence metal ion

(Ti4+1-x Nb5+

x )(O2-2-x N3-

x )

•Co-doping of nitrogen ion and lower valence anion

Ti(O2-2x N3+

x F-x )

33

34

Photocatalytic activity in deNOx by (a) blank (no catalyst), (b) undoped TiO2 (Degussa P25), (c) TiO2-x Ny and TiO2-x Ny co-doped with (d) 2 mol.%, (e) 6 mol.%, (f) 10 mol.%, and (g) 15 mol.% of Nb

Photocatalytic activity in deNOx by (a) blank (no catalyst), (b) undoped TiO2 (Degussa P25), (c) TiO2-x Ny and TiO2-x Ny co-doped with (d) 2 mol.%, (e) 6 mol.%, (f) 10 mol.%, and (g) 15 mol.% of Nb

627(R) 530(G) 445(B) 390(UV)0

5

10

15

20

25

30

35D

eNO x

abili

ty /

%

Wavelength / nm

BlankTiO2 (P25)TiO2-x Ny

Ti0.98 Nb0.02 O2-x Ny

Ti0.94 Nb0.06 O2-x Ny

Ti0.90 Nb0.10 O2-x Ny

Ti0.85 Nb0.15 O2-x Ny

Bla

nkTi

O2

(P25

)Ti

O2-

xNy

Ti0.

98N

b 0.0

2O2-

xNy

Ti0.

94N

b 0.0

6O2-

xNy

Ti0.

90N

b 0.1

0O2-

xNy

Ti0.

85N

b 0.1

5O2-

xNy

Improvement of photocatalytic activity by depressing the electron-hole recombination with heterogeneouos electron transfer

Composites with semiconductors possessing different band structures

TiO2-x Ny /TiO2

TiO2-x Ny /Fe2 O3

Composites with metalsTiO2-x Ny /Pt

Improvement of photocatalytic activity by depressing the electron-hole recombination with heterogeneouos electron transfer

Composites with semiconductors possessing different band structures

TiO2-x Ny /TiO2

TiO2-x Ny /Fe2 O3

Composites with metalsTiO2-x Ny /Pt

TiO2 Fe2 O3

CB

VB

-

+

hTiO2

VB

CB

D+

D

Pt

35

Reactor volume： 370 cm3、Gas flow rate：200 cm3/min、NO conc.：1 ppm Light soource：LED lamp (2mW/m2)Reactor volume： 370 cm3、Gas flow rate：200 cm3/min、NO conc.：1 ppm Light soource：LED lamp (2mW/m2)

Photocatalytic deNOx abilities evaluated by irradiating different LED lightsPhotocatalytic deNOx abilities evaluated by irradiating different LED lights

627nm 530nm 445nm 395 nm 0.5

0.6

0.7

0.8

0.9

1.0

on off on off on off on

BlankS-TiO2

NO

x C

once

ntra

tion

/ ppm

Time / min0 10 0 10 0 10 0 10

Red LED(627nm) Green LED(530nm) Blue LED(445nm) UV LED(627nm,1.98ev) (530nm, 2.34eV) (445nm, 2.79eV) (390nm, 3.18eV)

S-TiO2

TiO2-x Ny

TiO2-x Ny /0.5 wt% Fe

TiO2-x Ny /0.5 wt% Pt

627nm 530nm 445nm 395 nm

627nm 530nm 445nm 395 nm

627nm 530nm 445nm 395 nm

0.5

0.6

0.7

0.8

0.9

1.0


Red LED(627nm) Green LED(530nm) Blue LED(445nm) UV LED(627nm,1.98ev) (530nm, 2.34eV) (445nm, 2.79eV) (390nm, 3.18 eV)

TiONFe

NO

x C

once

ntra

tion

/ ppm

Time / min0 10 0 10 0 10 0 10

0.5

0.6

0.7

0.8

0.9

1.0


Red LED(627nm) Green LED(530nm) Blue LED(445nm) UV LED(627nm,1.98ev) (530nm, 2.34eV) (445nm, 2.79eV) (390nm, 3.18 eV

NO

x C

once

ntra

tion

/ ppm

Time / min0 10 0 10 0 10 0 10 0.5

0.6

0.7

0.8

0.9

1.0


Red LED(627nm) Green LED(530nm) Blue LED(445nm) UV LED(627nm,1.98ev) (530nm, 2.34eV) (445nm, 2.79eV) (390nm, 3.18 eV)

NO

x C

once

ntra

tion

/ ppm

Time / min0 10 0 10 0 10 0 10

627nm 530nm 445nm 395 nm

627nm 530nm 445nm 395 nm 627nm 530nm 445nm 395 nm

36

37

Composite with AttapulgiteComposite with Attapulgite

Applications: Constructing materials, Decolorizing agents, etc.

MgMg

55

(Si,Al)(Si,Al)

88

OO

2020

(OH)(OH)

22

･･8H8H

22

OOA natural mineralA natural mineral

AttapulgiteAttapulgite

TiO2-x Ny /Attapulgite

Adsorption abilityPhotocatalytic activity

38

Attapulgite Attapulgite+TiO2-x Ny

Sample Attapulgite TiO2-x Ny TiO2-x Ny /Attapulgite

Pore size (dV(d)) / nm

3.83 12.36 12.38

Pore volume / cm3/g

0.33 0.49 0.79

Specific surface area / m2/g

211 202 213

500 nm 500 nm

39

Influence of TiOInfluence of TiO22--xx NNyy contentcontent

NO destruction with TiO2-x Ny /attapulgite composites

>510 >400 >2900

10

20

30

40

50

60

70

Atta

pulg

iteA

ttap.

+ 1

0wt.%

TiO

2-xN

y

NO

dec

ompo

sed

(%)

Wavelength / nm

Atta

p. +

20w

t.% T

iO2-

xNy

TiO

2-xN

yP2

5

Emission spectra of CaAl2 O4 :(Eu,Nd)Emission spectra of CaAl2 O4 :(Eu,Nd)

After irradiation for 20 min under UV light.

Persistent Photocatalyst of Long After Glaw Phosphor/TiO2-x Ny

Composites

Persistent Photocatalyst of Long After Glaw Phosphor/TiO2-x Ny

Composites

40

350 400 450 500 550 6000

10

20

30

40

0 20 40 60 80 100 1200

10

20

30

40

Inte

nsity

/mcd

/m-2

Time /min

Inte

nsi

ty /

mcd/m

2

Wavelength /nm

Time0 min.

120 min.

Emission Spectrum & Diffuse Reflectance Spectra

TiO2 (P25)

TiO2-x Ny

CaAl2 O4 :(Eu,Nd)

41

200 300 400 500 600 700 8000

20

40

60

80

100

Emis

sion

inte

nsity

/a.u

.

Ref

lect

ance

/ %

Wavelength /nm

ex =325nm

42

Oxidative destruction of NO under irradiation of UV light and after turning off the light

0 50 100 150 2000

20

40

60

80

NO

dec

ompo

sed

/ %

Ligh

t off

Time /min

Ligh

t on

CaAl2 O4 :(Eu,Nd)/TiO2-x Ny

CaAl2 O4 :(Eu,Nd)/TiO2 (P25)

0 50 100 150 2000

20

40

60

80

Ligh

t off

Time /min

Ligh

t onNO

dec

ompo

sed

/ %

CaAl2 O4 :(Eu,Nd)/TiO2-x Ny

TiO2-x Ny

ConclusionsConclusions

Visible light responsive nitrogen-doped titania with high specific surface area were prepared by solvothermal reactions in mixed solution of TiCl3 -hexamethylenetetramine.

Nitrogen-doped titania showed excellent photocatalytic activity for the environmental clean-up.

The photocatalytic performance of nitrogen-doped titania could be improved by co-doping with higher valence metal ions and/or lower valence anion, and coupling with semiconductors, clay minerals and long afterglaw phosphors.

Visible light responsive nitrogen-doped titania with high specific surface area were prepared by solvothermal reactions in mixed solution of TiCl3 -hexamethylenetetramine.

Nitrogen-doped titania showed excellent photocatalytic activity for the environmental clean-up.

The photocatalytic performance of nitrogen-doped titania could be improved by co-doping with higher valence metal ions and/or lower valence anion, and coupling with semiconductors, clay minerals and long afterglaw phosphors.

43

44




Conclusion




Conclusion

45

UV Vis IR

Rad

iatio

n en

ergy

Wave length (nm)

Wave length (nm)

Solar spectraSolar spectra

45%5% 50%

Damages Caused by UV-rayDamages Caused by UV-ray

46

UV light

Degradation of organic materials

-CH2CHClCH2Cl- → CH2CHClCH=CH- + HCl

↓ Burning

Dioxin

Discoloration of painting

47

Damages to human

Sunburn

Acceleration of aging

Wrinkles

Cancer

Suntan

48

C C COOHHO

H

H

OCH3

HMCAtrans-4-hydroxy-3-

methoxycinnamic acid

Structures of Typical Organic UV- absorbents

COOHH2 N

PABAp-aminobenzoic acid

COOHHO

OCH3

HMBA4-hydroxy-3-methoxybenzoic

acid

N

N

CH CH COOH

H

UAurocanic acid

SO3 H

C

O

OCH3

OH

HMBSA2-hydroxy-4-methoxy-

benzophenone-5-sulfonic acid

49

Organic UV absorbents

Advantage Excellent UV absorption ability

Disadvantage Being absorbed in the body through the skin, raising safety concerns

Stable and safe inorganic UV absorbents

Light absorption by the electric transition of semiconductorEb =hhc

Cut off UV light (< 400 nm) Band gap energy: ca. 3 eV

50

Design of Inorganic UV-shielding MaterialsDesign of Inorganic UV-shielding Materials

Photocatalyst

Solar battery

Optical sensor

UV-shielding material

e-

h+

h Band gap energy

51

Light scatteringa) Geometrical scattering region

（d>>)s ∝

1/d b) Mie scattering region （d ～

l ）s ∝

d2f(ｄ/, n)The scattering becomes greatest when d=/2

c) Rayleigh scattering regions = K3 d6/4

The scattering is in proportion to the particle size to the sixth power

Rayleigh scattering

Mie scattering

Geometrical scattering

Improving the transparency in visible light range

Depression of light scattering

Decreasing the particle size to less than half of wavelength

(Nanoparticles of d<20 nm become quite transparent)

52

4 wt% TiO 24 wt% TiO2

30 wt% SiO2 coated CeO2

TiO2

Typical Inorganic UV-shielding MaterialsTypical Inorganic UV-shielding Materials

20 wt% SiO2 /CeO2

10 wt% ZnO10 wt% ZnO

CeO2e-

h +

hBand gap energy

O2

•O2-

H2 O

•OH + H+

O2 1O2

•OOHH+

Damaging

53

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7

ZnO (Sumitomo Osaka Cement ZnO-350)

TiO2 (Degussa P25)

Al2O3 & ZrO2 - co-coated TiO2

20 mol% CaO doped CeO2

Time (h)

Phen

ol re

mai

ned

(%)

Photocatalytic decomposition of phenol by irradiation of UV-ray from a 100 W high pressure UV lamp to 0.5 mM phenol aqueous solutions dispersed various samples

54

Plasmid DNA pUC 18 (A260 /A280 =1.76)Molecular weight 2,686 bpNIPPON GENE

Damages of DNA under UV irradiation in the presence of UV-shielding materilas Damages of DNA under UV irradiation in the presence of UV-shielding materilas

55

Analysis of DNA configulation

0

0.2

0.4

0.6

0.8

1.0

1.2

0 50 100 150 200 250 300Time / min

Rel

ativ

e in

tens

ity

CeO2

Ce1.8 Ca0.2 O1.8 /10 wt% SiO2

TiO2

Blank

Ce1.8 Ca0.2 O1.8

ZnO

H. Hidaka, H. Kobayashi,T. Koike, T. Sato and N. Serpone, DNA damage photoinduced by cosmetic pigments and sunscreen agents under solar exposure and artificial UV illumination, J. Oleo Sci.,55, 249-261 (2006).

Time dependence of the relative intensity of super coil configulation

56

Comfort

Good

Not good

Bad

Size, comfort and transparency of the powder when applied on the skin Size, comfort and transparency of the powder when applied on the skin

Transparency

Good

Bad

Particle sizeLarge

Small

UV-absorbent

White & color pigment

Pearl pigment

Scrub reagent

Extender pigment

(Plate-like particles)Mica, Talc, Plate- like silica, etc.

TiO2 , ZnO, CeO2

57

Decreasing UV- shielding ability

UV-shielding Material Composite

• UV-absorption ability

• Good comfort

• TiO2 nanoparticle

• ZnO nanoparticle

• Mica

• Talc

• Plate-like SiO2

（No UV-absorption ability）

58

• Excellent comfort when applied on the skin• Excellent coverage ability

Enhance the comfort as well as UV-shielding ability

Plate-like semiconductor microparticle

（Possessing UV-absorption ability）

Ce0.8 Ca0.2 O1.8 nanoparticle

（UV-absorbent）

Panoscopic assembling of ceria nanoparticlesUsing plate-like semiconductor

Panoscopic assembling of ceria nanoparticlesUsing plate-like semiconductor

59

Mica

K0.8 (Li0.266 Ti1.734 )O4 (E bg = ca. 3.5 eV) Ce2 (PO4 )2 HPO4H2 O (Ebg =ca. 2.6 eV)

60

Preparation of plate-like titanate

microparticle/calcia-doped ceria

nanoparticle composites

i. Coprecipitation method

ii. Sol-gel method

iii. Layer-by-layer assembling method

61

Preparation of K0.8 Li0.27 Ti1.73 O4 /Ce0.8 Ca0.2 O2 nanocompositesPreparation of K0.8 Li0.27 Ti1.73 O4 /Ce0.8 Ca0.2 O2 nanocomposites

62

Isoelectric points of plate-like titanate and calcia- doped ceria nanopaericles prepared at various pHs Isoelectric points of plate-like titanate and calcia- doped ceria nanopaericles prepared at various pHs

2 3 4 5 6 7 8 9-60

-40

-20

0

20

40Ze

ta p

oten

tial (

mV

)

Plate-like titanate

pH

Calcia-doped ceria

63

Preparation of ceramic composites using hetero coagulation Preparation of ceramic composites using hetero coagulation

CeO2

K0.8 (Li0.27 Ti1.73 )O4pH controlSurface charge control

CeO2

+

-

0

+

-

pH

------

-------

---

++

+

+K0.8 (Li0.27 Ti1.73 )O4

2.5 7.0

64

Plate-like titanate (PLT)/calcia-doped ceria (CDC) composites prepared at pH 6.5/12.0 with different CDC concentrations Plate-like titanate (PLT)/calcia-doped ceria (CDC) composites prepared at pH 6.5/12.0 with different CDC concentrations

10 wt% 40 wt% 70 wt%

70 wt%40 wt%10 wt%

pH=6.5

pH=12.0

redundant CDC

Agglomeration of CDC

65

Morphology of plate-like titanate (PLT)/calcia-doped ceria (CDC)Morphology of plate-like titanate (PLT)/calcia-doped ceria (CDC)

700 ºC 1 h

66

Equipment: KES-SE friction tester

(KES KATO TECH CO., LTD)

Test condition:Load weight: 25 gSlide speed: 0.5 mm/secFriction sensor: Piano threadSubstrate: artificial leather

A: P25 (TiO2 ); B: CDC (pH=12.0); C: Plate-like titanate (PLT) before coating; D: PLT/CDC 10 % (6.5); E: PLT/CDC 40 %(6.5); F: PLT/CDC 40 %(12.0); G: PLT/CDC 70% (6.5)

A B C E D GF0

10

20

30

40

50

60

70

80

Cha

nge

in d

ynam

ic fr

ictio

n co

effic

ient

/ o

x 10

0 (%

)

TiO2 (P25)

CDCPLT

6.5 70%

12.0 40%6.5 40%

6.5 10%

PLT/CDC

Kinetic friction coefficient of the artificial leather before and after applying various sample powders on.

o : Artificial leather without sample,

: Artificial leather applied the sample powder on

Kinetic friction coefficient of the artificial leather before and after applying various sample powders on.

o : Artificial leather without sample,

: Artificial leather applied the sample powder on

67

PLT before coating

PLT/CDC with high CDC concentration

PLT/CDC with proper CDC concentration

Rolling friction of shperical particles

Slip friction of plate-like particles

Slip friction of nanoparticles

68

UV-shielding abilityUV-shielding ability

The UV-shielding ability of PLT/CDC increased with increasing CDC content

UV-shielding ability of PLT/CDC prepared by sol-gel method was higher than that by co-precipitation method

69

Improving the comfort and covering ability of inorganic nanoparticles by the panoscopic assembling using plate-like particles

K0.80 Ti1.73 Li0.27 O4 As-prepared K0.80 Ti1.73 Li0.27 O4 / 50 wt% Ce0.8 Ca0.2 O1.8

Ce0.8 Ca0.2 O1.8

30 m

(b)

30 m

(a)

20 nm

(c)

70

Nanocomposites of plate-like K0.81 Li0.27 Ti1.73 O4 microparticles/ Ce0.8 Ca0.2 O1.8 nanoparticles were prepared by coprecipitation method.

Panoscopic assembling of Ce0.8 Ca0.2 O1.8 nanoparticles with plate-like K0.81 Li0.27 Ti1.73 O4 was useful to improve the comfort when applied to the skin as well as the UV-shielding performance.

Nanocomposites of plate-like K0.81 Li0.27 Ti1.73 O4 microparticles/ Ce0.8 Ca0.2 O1.8 nanoparticles were prepared by coprecipitation method.

Panoscopic assembling of Ce0.8 Ca0.2 O1.8 nanoparticles with plate-like K0.81 Li0.27 Ti1.73 O4 was useful to improve the comfort when applied to the skin as well as the UV-shielding performance.

New Inorganic UV-shielding Materials

with Safe, Comfort and Excellent UV-shielding Ability

71



Design and Development of Ceria-based Inorganic UV-shielding Materials

Conclusion



Design and Development of Ceria-based Inorganic UV-shielding Materials

Conclusion

72

Nanocomposites of nitrogen-doped titanina nanoparticles and semiconductor possessing different band gap, clay mineral such as attapulgite, long afterglow phosphor, etc. showed excellent photocatalytic performance for environmenta clean-up.

Nanocomposites of Ce0.8 Ca0.2 O1.8 nanoparticles and plate-like semiconductors possessing UV- shielding ability, such as K0.81 Li0.27 Ti1.73 O4 showed excellent UV-shielding performance for human health as well as excellent comfort when applied to the skin.

panoscopic assembling of ceramic materials for ... tsugio sato institute of multidisciplinary...

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