Post on 13-Apr-2018
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
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
3
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
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
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
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
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
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
on off on off on off on
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
on off on off on off on
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
on off on off on off on
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
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
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
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
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
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
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
Conclusion
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
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.