Semiconductor Metal Oxide Nanoparticles for Visible Light Photocatalysis

1. 1
Recent Progress of Photocatalytic Water
Splitting and Preliminary Work
Zhibin Lei
Supervisor: Prof. Can Li
Jan. 13, 2003
State Key laboratory of Catalysis, Dalian Institute of Chemical Physics

2. ☻ Significance of hydrogen energy
☻ Mechanism of photocatalytic water
splitting
☻ Recent development of water splitting
☻ My preliminary work and next plan
Content

3. 3
The concentration change of CO2 in air during
the past one thousand years
Significance of hydrogen energy

4. 4
1996 1997 1998 1999 2000 2001
0
500
1000
1500
2000
2500
3000
3500
4000
Year
The funds used for the hydrogen project of
USA in the past six years

5. 5
我国未来所需氢的预测结果（万吨）
项 目 2010 2020 2050
合成氨 768 936.2 936.2
炼油厂加氢精制 773.1 1141.7 1141.7
燃料电池电动车 326.6 967 8758.4
燃料电池发电 73.2 216.7 1962.8
合 计 1939.1 3261.6 12799.1

6. 6
Predict hydrogen source in the next fifty years

7. 每年投射到地面上的太阳能约1.05×1018kWh，
相当于1.3×106亿吨标准煤
• Energy source
• Environment
• Economy
Photocatalyst
H2O H2 + ½ O2
hv

8. A.Fijishima and K.Honda. Nature. 1972, 238, 37.
TiO2 + 2 hv 2 e–+2 h+ (1) (at the TiO2 electrode)
2 H+ + 2 e– H2 (2) (at the Pt electrode)
H2O + 2 h+ 1/2 O2 + 2 H+ (3) (at the TiO2 electrode)
H2O + 2 hv 1/2 O2 + H2 (4) (overall reaction)
Mechanism of photocatalytic water splitting

9. 9
Pt
H+
H2
hv
H2O
O2
h+
e-
VB
CB
RuO2
Schematic Water oxidation and reduction process
over photocatalyst

10. 10
h+
e-
VB
CB H+/H2
O2/H2O
2
1
0
-1
E vs NHE(pH=0)
0 V
1.23 V
badgap
The relationship between the redox potential of H2O
and the VB-CB of the semiconductor

11. 11
e-
e-
e-+h+
h+
h+
H+
H2
H2O
O2
CB
VB
h+
e-
hv
hv
Schematic photoexicitation process in semiconductor

12. 12
300 400 500 600 700 800 900 1000
0.0
0.5
1.0
1.5
relative
intensity
(a.u.)
Wavelengthen / nm
Solar energy distribution detected at PM 12 in Japan

13. 13
Vis 400-700nm
UV <400nm
IR >700nm

14. 14
O2p
N2p
M nd
CB
VB
S3p
Energy level diagram of transition metal oxide,
nitride and sulfide

15. 15
UV-Vis diffuse reflection spectra for Sm2Ti2O7 and Sm2Ti2S2O5
A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547.
Recent development of water splitting

16. 16
A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547.
Time course of O2 evolution from Sm2Ti2S2O5 and CdS under
visible light irridiation (Condition catalyst: 0.2g, La2O3, 0.2g,
0.01M AgNO3 solution 200ml)

17. 17
A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547.
Time course of H2 evolution from 1.0 wt %Pt- Sm2Ti2S2O5 under visible
light irradiation( > 440nm, catalyst, 0.2g; solution volume, 200ml)
0.01M Na2SO3
+ 0.01M Na2S
20ml CH3OH
+180ml H2O

18. 18
A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547.
Estimated band position of Sm2Ti2S2O5 at pH = 0 and 8

19. 19
A. Kudo et al, Chem. Comm., 2002, 1958.
Diffuse reflection spectra of AgInZn7S9 (a), ZnS (b) and AgInS2 (c).
AgInS2
AgInZn7S9
ZnS

20. 20
A. Kudo et al, Chem. Comm., 2002, 1958.
Photocatalytic H2 evolution over AgInZn7S9(a) and 3wt%-Pt
/AgInZn7S9 under visible light irradiation(>420nm, catalyst,
0.3g; 0.25 M K2SO3- 0.35 M Na2S solution 300 ml.

21. 21
The set up for photocatalytic water splitting
My preliminary work and next plan

22. 22
0 2000 4000 6000 8000 10000
0.0
0.5
1.0
1.5
2.0
2.5
3.0
S<9120
Amount
of
H
2
/

mol
Area
Low yield part (S<9120) hydrogen evolution
standard curve for System-1 and System-2(S-1, S-2)
Y = 2.60E-4*X+0. 29
R = 0.99676

23. 23
0 20 40 60 80 100 120 140 160
0
50
100
150
200
250
300
9120<S<1400000
Amount
of
H
2
/

mol
Area / X 10000
Middle yield part (9120<S<1400000) hydrogen
evolution standard curve for S-1 and S-2
Y = 1.92-4*X+2.31
R = 0.99978

24. 24
Y = 3.18E-4*X-159.6
R = 0.99787
0 400 800 1200 1600 2000
0
1000
2000
3000
4000
5000
6000
7000
S>1400000
Amount
of
H
2
/

mol
Area / X 10000
High yield part (S>1400000) hydrogen evolution
standard curve for S-1 and S-2

25. 25
0 200 400 600 800 1000 1200 1400 1600
0
500
1000
1500
2000
2500
3000
Amount
of
O
2
/

mol
Area
Y = 1.92E-3*X-2.63
R = 0.99951
Oxygen evolution standard curve for S-1 and S-2

26. 26
0 200 400 600 800 1000 1200 1400 1600
0
500
1000
1500
2000
2500
3000
3500
4000
Amount
of
N
2
/

mol
Area / X1000
Y =2.56E-3*X-3.50
R = 0.99951
Nitrogen evolution standard curve for S-1 and S-2

27. 27
0 5 10 15 20 25
0
40
80
120
160
200
B
Amount
of
O
2
/

mol
Time / hours
0 5 10 15 20 25
5
10
15
20
25
30
35
A
Amount
of
H
2
/

mol
Time / hours
Time course of H2(A) and O2(B) evolution over CdO-360
(condition catalyst, 0.5g; 300W xenon lamp)
CH3OH 30ml,
H2O 170ml
0.01M AgNO3
200ml, >420nm

28. 28
0 2 4 6 8 10 12 14 16 18
0
20
40
60
80
100
120
140
500
600
360
400
Amount
of
O
2
evolution
/

mol
Time / hours
Photocatalytic O2 evolution over CdO calcinated at varying
temperature(Condition: catalyst 0.5g, 0.01M AgNO3 200ml)

29. 29
0 5 10 15 20 25 30 35 40 45 50
0
50
100
150
200
250
300
350
400
450
CdO-400+La2
O3
CdO-400
Amount
of
O
2
/

mol
Time / hours
Effect of La2O3 on the activity of the CdO calcinated at
400°C

30. 30
0 10 20 30 40 50
0
100
200
300
400
Amount
of
O
2
/

mol
Time / hours
CdO-500-la2O3
CdO-400-la2O3
Photocatalytic O2 evolution over CdO calcinated at 400 and
500C(Condition: catalyst 0.5g; 0.01M AgNO3 200ml; la2O3, 0.2g)

31. 31
0 5 10 15 20 25 30 35 40 45 50
0
50
100
150
200
250
300
350
400
CdO-400-La2
O3
1% RuO2
-CdO-400
Amount
of
O
2
/

mol
Time / hours
Photocatalytic O2 evolution over CdO-400 and 1% RuO2 loaded
CdO-400(Condition: catalyst 0.5g; 0.01M AgNO3 200ml; La2O3, 0.2g)

32. 32
0 5 10 15 20 25 30
0
50
100
150
200
250
300
350
Amount
of
O
2
/

mol
Time / hours
Photocatalytic O2 evolution over CdO calcinated at 400°C
(Condition: catalyst 0.5g, 0.01M AgNO3 200ml, La2O3 0.2g)
R = 11.2mol/h

33. 33
0 5 10 15 20 25 30
0
40
80
120
160
200
240
3%-RuO2
-(CdO-500)
2%-RuO2
-(CdO-500)
CdO-500
Amount
of
O
2
/

mol
Time / hours
Photocatalytic O2 evolution over CdO-500 and RuO2 loaded CdO-
500(Condition: catalyst 0.5g; 0.01M AgNO3 200ml; La2O3, 0.2g)

34. 34
200 300 400 500 600 700 800
0.0
0.2
0.4
0.6
0.8
1.0
ABS
wavelengthen / nm
B
C
D
Uv-Vis diffuse reflection spectra for CdO prepared
at different temperature
360
400
500

35. 35
10 20 30 40 50 60 70
0
100
200
300
400
Intensity
(a.u.)
degree / 2
XRD pattern of CdO calcinated at 360C

36. 36
200 300 400 500 600 700 800
0.0
0.2
0.4
0.6
0.8
1.0
Intensity(a.u.)
wavelengthen / nm
CdIn2S4
CdS
UV-Vis diffuse reflection spectra for CdS and CdIn2S4
prepared by the solvothermal method.

37. 37
10 20 30 40 50 60 70
0
200
400
600
800
1000
1200
1400
1600
1800
2000
CdIn2
S4
-2
CdIn2
S4
-1
Intensity
 / degree
XRD pattern of CdIn2S4 prepared by solvothermal method

38. 38
Next Plans
1 To investigate the influence of other electron
acceptor such as Fe3+ and its concentration on
the activity of CdO system.
2 To explore how the different loading species
with varying amount will influence the O2
evolution.
3 To synthesize Cr or Ni doped CdO to enhance
the position of VB of CdO.
4 To synthesize other sulfide with better activity.