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1 Recent Progress of Photocatalytic Water Splitting and Preliminary Work Zhibin Lei Supervisor:...
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Transcript of 1 Recent Progress of Photocatalytic Water Splitting and Preliminary Work Zhibin Lei Supervisor:...
1
Recent Progress of Photocatalytic Water Splitting and Preliminary Work
Zhibin LeiSupervisor: Prof. Can Li
Jan. 13, 2003
State Key laboratory of Catalysis, Dalian Institute of Chemical Physics
☻ Significance of hydrogen energy
☻ Mechanism of photocatalytic water
splitting
☻ Recent development of water splitting
☻ My preliminary work and next plan
Content
3
The concentration change of CO2 in air during the past one thousand years
Significance of hydrogen energy
4
1996 1997 1998 1999 2000 20010
500
1000
1500
2000
2500
3000
3500
4000
Year
The funds used for the hydrogen project of USA in the past six years
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
6Predict hydrogen source in the next fifty years
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
PhotocatalystH2O H2 + ½ O2
hv
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
PtH+
H2
hv
H2O
O2
h+
e-
VB
CB
RuO2
Schematic Water oxidation and reduction process over photocatalyst
10
h+
e-
VB
CB H+/H2
O2/H2O
2
1
0
-1
E vs NHE(pH=0)
0 V
1.23 Vbadgap
The relationship between the redox potential of H2O and the VB-CB of the semiconductor
11
e-
e-
e-+h+
h+
h+H+
H2
H2O
O2
CB
VBh+
e-
hvhv
Schematic photoexicitation process in semiconductor
12
300 400 500 600 700 800 900 1000
0.0
0.5
1.0
1.5re
lati
ve in
tens
ity
(a.u
.)
Wavelengthen / nm
Solar energy distribution detected at PM 12 in Japan
13Vis 400-700nm
UV <400nm
IR >700nm
14
O2p
N2p
M nd
CB
VB
S3p
Energy level diagram of transition metal oxide, nitride and sulfide
15UV-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
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, 0.0
1M AgNO3 solution 200ml)
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
A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547.
Estimated band position of Sm2Ti2S2O5 at pH = 0 and 8
19
A. Kudo et al, Chem. Comm., 2002, 1958.
Diffuse reflection spectra of AgInZn7S9 (a), ZnS (b) and AgInS2 (c).
AgInS2AgInZn7S9ZnS
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 The set up for photocatalytic water splitting
My preliminary work and next plan
22
0 2000 4000 6000 8000 100000.0
0.5
1.0
1.5
2.0
2.5
3.0
S<9120A
mou
nt o
f H
2 / m
ol
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
0 20 40 60 80 100 120 140 160
0
50
100
150
200
250
300
9120<S<1400000A
mou
nt o
f H
2 / m
ol
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
Y = 3.18E-4*X-159.6
R = 0.99787
0 400 800 1200 1600 20000
1000
2000
3000
4000
5000
6000
7000
S>1400000A
mou
nt o
f H
2 / m
ol
Area / X 10000
High yield part (S>1400000) hydrogen evolution standard curve for S-1 and S-2
25
0 200 400 600 800 1000 1200 1400 16000
500
1000
1500
2000
2500
3000A
mo
un
t o
f O
2 / m
ol
Area
Y = 1.92E-3*X-2.63
R = 0.99951
Oxygen evolution standard curve for S-1 and S-2
26
0 200 400 600 800 1000 1200 1400 16000
500
1000
1500
2000
2500
3000
3500
4000A
mo
un
t o
f N
2 /
mo
l
Area / X1000
Y =2.56E-3*X-3.50
R = 0.99951
Nitrogen evolution standard curve for S-1 and S-2
27
0 5 10 15 20 25
0
40
80
120
160
200
B
Am
ou
nt
of
O2
/ m
ol
Time / hours
0 5 10 15 20 25
5
10
15
20
25
30
35
A
Am
ou
nt
of
H2
/ m
ol
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
0 2 4 6 8 10 12 14 16 18
0
20
40
60
80
100
120
140
500
600
360
400
Am
ou
nt
of
O2
evo
luti
on
/ m
ol
Time / hours
Photocatalytic O2 evolution over CdO calcinated at varying te
mperature(Condition: catalyst 0.5g, 0.01M AgNO3 200ml)
29
0 5 10 15 20 25 30 35 40 45 50
0
50
100
150
200
250
300
350
400
450
CdO-400+La2O
3
CdO-400Am
ou
nt
of
O2
/ m
ol
Time / hours
Effect of La2O3 on the activity of the CdO calcinated at 400°C
30
0 10 20 30 40 50
0
100
200
300
400
Am
ou
nt
of
O2
/ m
ol
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
0 5 10 15 20 25 30 35 40 45 50
0
50
100
150
200
250
300
350
400
CdO-400-La2O
3
1% RuO2-CdO-400A
mo
un
t o
f O
2 /
mo
l
Time / hours
Photocatalytic O2 evolution over CdO-400 and 1% RuO2 loaded Cd
O-400(Condition: catalyst 0.5g; 0.01M AgNO3 200ml; La2O3, 0.2g)
32
0 5 10 15 20 25 30
0
50
100
150
200
250
300
350
Am
ou
nt
of
O2
/ m
ol
Time / hours
Photocatalytic O2 evolution over CdO calcinated at 400°C (Co
ndition: catalyst 0.5g, 0.01M AgNO3 200ml, La2O3 0.2g)
R = 11.2mol/h
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
Am
ou
nt
of
O2
/ m
ol
Time / hours
Photocatalytic O2 evolution over CdO-500 and RuO2 loaded CdO-5
00(Condition: catalyst 0.5g; 0.01M AgNO3 200ml; La2O3, 0.2g)
34
200 300 400 500 600 700 800
0.0
0.2
0.4
0.6
0.8
1.0
AB
S
wavelengthen / nm
B C D
Uv-Vis diffuse reflection spectra for CdO prepared
at different temperature
360400500
35
10 20 30 40 50 60 700
100
200
300
400In
ten
sity
(a.
u.)
degree / 2
XRD pattern of CdO calcinated at 360C
36
200 300 400 500 600 700 800
0.0
0.2
0.4
0.6
0.8
1.0
Inte
ns
ity
(a.u
.)
wavelengthen / nm
CdIn2S4 CdS
UV-Vis diffuse reflection spectra for CdS and CdIn2S4 pre
pared by the solvothermal method.
37
10 20 30 40 50 60 70
0
200
400
600
800
1000
1200
1400
1600
1800
2000
CdIn2S
4-2
CdIn2S
4-1
Inte
nsit
y
/ degree
XRD pattern of CdIn2S4 prepared by solvothermal method
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.