ICWES15 - Preparation of Mesoporous Titania Photocatalyst for Water Treatment Application. ...
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Transcript of ICWES15 - Preparation of Mesoporous Titania Photocatalyst for Water Treatment Application. ...
Preparation of Mesoporous Titania Photocatalyst for Water Treatment
ApplicationXingdong Wang1, David R.G.Mitchell2, Patrick Hartley1 and Rachel A. Caruso1,3
1 CMSE, CSIRO Material Science and Engineering, 2 Australia Center for Microscopy and Microanalysis, The University of Sydney, 3 PFPC, School of Chemistry, The University of Melbourne
My background
Environmental pollution remediation ---principle of photocatalysis
http://www.mchnanosolutions.com/whatis.html
High recombination rate of e-/h+ pairs (~90%) Inactive under visible light (wide band gap---3.2 eV for anatase TiO2)
Outline of Porous TiO2 Project---Environmental pollution remediation
Enhancing photocatalytic (PC) activity UV light: decrease charge recombination (e-/h+) Visible light: narrow TiO2 band gap
Crystal properties Surface properties Porosity Band gap …
X. D. Wang, R. A. Caruso, J. Mater. Chem. 2011, 21, 20.
Control Material properties
X. Chen, S. S. Mao, Chem. Rev., 2007, 107, 2891.
Composition Crystal phase Morphology
Preparation of TiO2
Synthesis of porous TiO2 materials
Composition Composition and Crystal phase
Morphology: beads Morphology: fibre
X .D. Wang, G.I. N. Waterhouse, D. R. G. Mitchell, K. Prince, R. A. Caruso, submitted
X. D. Wang, M. Blackford, K. Prince, R. A. Caruso, submitted
X. D. Wang, L. Cao, D.H. Chen, R. A. Caruso, in preparation
Ongoing project: collaboration with J. choi, Y.
B. Truong, and L.Kyratzis
UV light PC increase: Noble metal deposition decrease recombination of e-/h+
Crystal phase & Boron doping: band gap Noble metal deposition: Visible light PC: increased
400 nm
TiCl3
Hydrolysis & condensation
NaOH
AmorphousTiO2
Washing
Solvothermal: 160°C, 16h
Crystallized TiO2
NaOH (mol) 0.041 0.054 0.059 0.068 0.070 0.073 0.076
Solution pH 0.25 0.56 0.80 7.92 7.98 9.67 11.58
Synthesis scheme
Surface area
0
50
100
150
200
250
300
0.25 0.56 0.80 7.92 7.98 11.58 P25
pH during the synthesis
Su
rfac
e ar
ea (
m2 g
-1)
Pore size distribution
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 20 40 60 80 100 120 140 160Pore diameter (nm)
dV
/dlo
gD
(cm
3/g
) 0.250.567.927.9811.58
-0.1
0.4
0.9
1.4
0 5 10 15 20
Morphology-SEM
0.25
7.98
11.58
Morphology and porosity -TEM
0.25 11.587.98
5 15 25 35 45 55 65 75 85
2 theta (degree)
Inte
ns
ity
(a.
u.)
0.25
0.80
7.92
7.98
9.67
11.58
Crystal phase
Anatase
Rutile
Titanate
Acid condition: rutile phaseNeutral condition: anatase phase (slight brookite)Alkaline condition: titanate phase
8Å
Surface hydroxyl groups (FT-IR)
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
1000150020002500300035004000
Wavenumber (cm-1)
abs
(a.
u.)
0.250.807.929.6711.58
Ti-OH
Ti…H2O
Diffuse UV-Vis and band gap
0
10
20
30
40
50
60
70
80
90
100
200 300 400 500 600 700 800
Wavelength (nm)
Ref
lect
ance
(%
)
P25 0.25 7.98 11.58
Diffuse UV-vis and Band gap
0
1
2
3
4
5
6
7
8
9
10
2.5 3 3.5 4
E (eV)
(F(r
)E)1
/2
11.587.987.929.670.560.25 pH9.67: 3.25 eV
pH11.58: 3.22 eV
pH7.98: 3.15 eV
pH0.56: 2.98 eV
pH7.92: 3.13 eV
pH0.25: 3.00 eV
pH 0.25 0.56 7.92 7.98 9.67 11.58 P25
Bg (eV) 3.00 2.98 3.13 3.15 3.25 3.22 3.10
Adsorption test
Test conditions: 100 ppmIn the dark: shaking overnight (pH 5.10)
0
10
20
30
40
50
60
70
80
90
100
0.25 0.8 7.92 7.98 9.67 11.58 P25 AC
Ad
sorp
tio
n o
f M
B (
pp
m)
Set up: 500 Watt Hg(Xe) lamp with band pass visible light filter (420-650 nm) Methylene blue (MB) as a probe molecule RSD< 3%
Photocatalysis reaction
Photocatalytic activity
Test conditions: 12.5 ppm of MBVisible light: 120 min at pH 5.10
pH
40
50
60
70
80
90
100
0 20 40 60 80 100 120
Degradation time (min)
C/C
0 *
100%
0.250.807.927.989.67P2511.58
Conclusions
• Solvothermal treatment produced high surface area TiO2.
• The material properties are pH dependant.
• The porous TiO2 prepared at pH 7.98 showed highest adsorption capacity.
• The maximum photocatalytic activity was for the sample prepared at pH 11.58.
Acknowledgements
• My supervisor (Dr Rachel Caruso) & group members • Internal collaborations (Dr Patrick Hartley and Darryl Wells)• Synchrotron PD teams (Dr Qinfen Gu, Justin Kimpton & Kia
Wallwork )• Dr Nathan Webster for help with synchrotron data analysis
CSIRO Materials Science and EngineeringDr Xingdong Wang
Ph: +61 3 9545 2689Email: [email protected]: www.csiro.au/cmse
CSIRO Materials Science and EngineeringDr Rachel Caruso OCE Science leader | Advanced Porous Materials Ph: +61 3 9545 7960Email: [email protected]: www.csiro.au/cmse