quantum dot self-decorated tio 2 nanosheet
DESCRIPTION
IUMRS-ICAM2013,Qingdao,Sep.22-28. Quantum dot self-decorated TiO 2 nanosheet. Feng-Min Zhao Tianjin University, China Sep. 24 2013. Contents. Introduction. 1. 2. Experimental. 3. Results and discussion. 4. Conclusions. Introduction.TRANSCRIPT
Quantum dot self-decorated TiO2 nanosheet
Feng-Min Zhao
Tianjin University, China
Sep. 24 2013
IUMRS-ICAM2013,Qingdao,Sep.22-28
2
3
4
1 Introduction
Experimental
Results and discussion
Conclusions
Contents
Chem. Soc. Rev., 2009, 38, 253-278.
Solar Energy
Introduction
<5%
Nature, 2008, 453, 638-641.
Faceted Anatase
Introduction
Faceted Anatase with Mesopores
Using MSC films, thefabricated all-solid-state, low-temperature sensitized solar cells that have 7.3 % efficiency, the highest efficiency yet reported.
Nature, 2013, 495, 215-219
truncated tetragonal bipyramid anatase
Science, 2001, 293, 269-271.
JACS, 2008, 130, 5018-5019.
Doping
Introduction
Science, 2011, 331, 746-750.
Experimental
TBOT + HF(40 wt%)
hydrothermally
treated at 180o
C
24h 72h 168h
A-t: NaOHA-tH: NaOH 100 oC 24hA-tC: NaOH 500 oC 2h
10 20 30 40 50 60 70 80
A-168C
A-168H
A-168
A-72
215
220
20421
110
5
200
004
Inte
ns
ity
(a
.u.)
2Theta (degree)
101
A-24
a
0 100 200 300 400 500 600 700 800
0.0
0.2
0.4
0.6
0.8
1.0
Eg
A1gB1g
No
rmal
ized
In
ten
sity
Raman shift ( cm-1)
A-24 A-72 A-168 A-168H A-168C
Egb
Results and discussion
24h
72h
168h
Results and discussion
24h
72h
168h
0 100 200 300 400 500 600 700 800
0.0
0.2
0.4
0.6
0.8
1.0
Eg
A1gB1g
No
rmal
ized
In
ten
sity
Raman shift ( cm-1)
A-24 A-72 A-168 A-168H A-168C
Egb
According to J. Phys. Chem. C 2012, 116, 7515 − 7519
SampleSide
length a/nm
Thickness
b/nm
Percentage of
{001} facets/%
SBET
/(m2 g–1)
A-24 55.2 5.4 83.7 69.4A-24H 55.1 5.6 83.1 68.5A-72 80.5 9.2 81.3 43.8
A-72H 79.8 9.1 81.4 44.1A-168 88.3 10.3 81.1 38.8
A-168H 89.0 10.1 81.6 36.8A-168C 88.8 10.3 81.2 17.4
%S{001}exp
=S{001}/(S{101}+S{001}) =2a2/{4ab+2a2]*100
350 400 450 500
3.0 3.2 3.4Photon energy (eV)
(ahv)
1/2 (e
V)1/
2
168h
24h
A-24 A-72 A-168 A-168H A-168C
Ab
sorp
tio
n (
a.u
.)
Wavelength (nm)
0.08 eV
UV-vis DRS
Results and discussion
-5 0 5 10 15 20 25
0.67 eV
c/s
Binding Energy (eV)
A-24 A-72 A-168 A-168H A-168C
O2s
XPS O2s
3200 3300 3400 3500 3600
g=1.961Inte
nsit
y (
a.u
.)
Magnetic Field (Gauss)
A-24 A-72 A-168 A-168C A-168H
g=1.989
EPR (110 K)
Results and discussion
468 466 464 462 460 458 456
468 466 464 462 460 458 456 454c/s
Binding Energy (eV)
A-24 A-72 A-168 A-168H A-168C
Ti4+Ti4+
Ti3+
Ti4+
XPS
0
2
4
6
8
10
P-25A-168A-72
k/S
BE
T (
10
-4 g
m-2 m
in-1)
Samples
Fresh sample
Hydrothermal sample at 100 oC
Calcined sample at 500 oC
A-24
Photodegradation of RhB
Post-hydrothermal Post-calcination
10 20 30 40 50 60 70 80
A-168C
A-168H
A-168
A-72
215
220
20421
110
5
200
004
Inte
ns
ity
(a
.u.)
2Theta (degree)
101
A-24
a
Results and discussion
A-168H: 3.4 times higher than A-24 2.7 times higher than P-25
Results and discussion
1
2
3
5
4
Ag photo-deposition on A-168H(d) and A-24(e)
0 2000 4000 6000 8000 10000
CuTi
AgO
Cu
Co
un
ts (
a.u
.)
C
Ag
Ag
Ag
1
2
3
4
5
Energy (KeV)
TEM-EDS
Conclusions
The long-time hydrothermal strategy and subsequent defect healing are the keys to obtain defect-free nanosheets decorated with TiO2 quantum dots.
The size of nanosheets progressively increases with t, but the {001} percentage almost remains unchanged (81–83%).
The surface Ti3+ defects suppress the photoactivity and could be removed by
hydrothermal treatment or calcination.
The quantum dots provide a new and more effective charge separation and transfer pathway over the nanosheet surfaces, and promote the photoactivity significantly.
Quantum dot self-decorated TiO2 nanosheet