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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
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☻ Significance of hydrogen energy ☻ Mechanism of photocatalytic water splitting ☻ Recent development of water splitting ☻ My preliminary work and next plan Content
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3 The concentration change of CO 2 in air during the past one thousand years Significance of hydrogen energy
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4 The funds used for the hydrogen project of USA in the past six years
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5 我国未来所需氢的预测结果(万吨) 项 目项 目 201020202050 合成氨 768936.2 炼油厂加氢精制 773.11141.7 燃料电池电动车 326.69678758.4 燃料电池发电 73.2216.71962.8 合 计 1939.13261.612799.1
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6 Predict hydrogen source in the next fifty years
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每年投射到地面上的太阳能约 1.05×10 18 kWh , 相当于 1.3×10 6 亿吨标准煤 Energy source Environment Economy Photocatalyst H2OH2O H 2 + ½ O 2 hvhv
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A.Fijishima and K.Honda. Nature. 1972, 238, 37. TiO 2 + 2 hv 2 e – +2 h + (1) (at the TiO 2 electrode) 2 H + + 2 e – H 2 (2) (at the Pt electrode) H 2 O + 2 h + 1/2 O 2 + 2 H + (3) (at the TiO 2 electrode) H 2 O + 2 hv 1/2 O 2 + H 2 (4) (overall reaction) Mechanism of photocatalytic water splitting
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9 Pt H+H2H+H2 hv H2OO2H2OO2 h+h+ e- VB CB RuO 2 Schematic Water oxidation and reduction process over photocatalyst
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10 h+h+ e- VB CB H + /H 2 O 2 /H 2 O 2 1 0 E vs NHE(pH=0) 0 V 1.23 V badgap The relationship between the redox potential of H 2 O and the VB-CB of the semiconductor
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11 e-e- e-e- e - +h + h+h+ h+h+ H+H2H+H2 H2OO2H2OO2 CB VB h+h+ e-e- hv Schematic photoexicitation process in semiconductor
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12 Solar energy distribution detected at PM 12 in Japan
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13 Vis 400-700nm UV <400nm IR >700nm
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14 O2p N2p M nd CB VB S3p Energy level diagram of transition metal oxide, nitride and sulfide
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15 UV-Vis diffuse reflection spectra for Sm 2 Ti 2 O 7 and Sm 2 Ti 2 S 2 O 5 A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547. Recent development of water splitting
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16 A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547. Time course of O 2 evolution from Sm 2 Ti 2 S 2 O 5 and CdS under visible light irridiation (Condition catalyst: 0.2g, La2O3, 0.2g, 0.01M AgNO3 solution 200ml )
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17 A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547. Time course of H 2 evolution from 1.0 wt %Pt- Sm 2 Ti 2 S 2 O 5 under visible light irradiation( > 440nm, catalyst, 0.2g; solution volume, 200ml) 0.01M Na 2 SO 3 + 0.01M Na 2 S 20ml CH 3 OH +180ml H 2 O
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18 A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547. Estimated band position of Sm 2 Ti 2 S 2 O 5 at pH = 0 and 8
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19 A. Kudo et al, Chem. Comm., 2002, 1958. Diffuse reflection spectra of AgInZn 7 S 9 (a), ZnS (b) and AgInS 2 (c). AgInS 2 AgInZn 7 S 9 ZnS
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20 A. Kudo et al, Chem. Comm., 2002, 1958. Photocatalytic H 2 evolution over AgInZn 7 S 9 (a) and 3wt%-Pt /AgInZn 7 S 9 under visible light irradiation( >420nm, catalyst, 0.3g; 0.25 M K 2 SO 3 - 0.35 M Na 2 S solution 300 ml.
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21 The set up for photocatalytic water splitting My preliminary work and next plan
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22 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
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23 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
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24 Y = 3.18E-4*X-159.6 R = 0.99787 High yield part (S>1400000) hydrogen evolution standard curve for S-1 and S-2
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25 Y = 1.92E-3*X-2.63 R = 0.99951 Oxygen evolution standard curve for S-1 and S-2
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26 Y =2.56E-3*X-3.50 R = 0.99951 Nitrogen evolution standard curve for S-1 and S-2
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27 Time course of H 2 (A) and O 2 (B) evolution over CdO-360 (condition catalyst, 0.5g; 300W xenon lamp) CH 3 OH 30ml, H 2 O 170ml 0.01M AgNO 3 200ml, >420nm
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28 Photocatalytic O 2 evolution over CdO calcinated at varying temperature(Condition: catalyst 0.5g, 0.01M AgNO 3 200ml)
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29 Effect of La 2 O 3 on the activity of the CdO calcinated at 400°C
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30 CdO-500-la 2 O 3 CdO-400-la 2 O 3 Photocatalytic O 2 evolution over CdO calcinated at 400 and 500 C(Condition: catalyst 0.5g; 0.01M AgNO 3 200ml; la 2 O 3, 0.2g)
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31 Photocatalytic O 2 evolution over CdO-400 and 1% RuO 2 loaded CdO-400(Condition: catalyst 0.5g; 0.01M AgNO 3 200ml; La 2 O 3, 0.2g)
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32 Photocatalytic O 2 evolution over CdO calcinated at 400°C (Condition: catalyst 0.5g, 0.01M AgNO 3 200ml, La 2 O 3 0.2g) R = 11.2 mol/h
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33 Photocatalytic O 2 evolution over CdO-500 and RuO 2 loaded CdO- 500(Condition: catalyst 0.5g; 0.01M AgNO 3 200ml; La 2 O 3, 0.2g)
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34 Uv-Vis diffuse reflection spectra for CdO prepared at different temperature 360 400 500
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35 XRD pattern of CdO calcinated at 360 C
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36 200300400500600700800 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 CdIn 2 S 4 prepared by the solvothermal method.
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37 XRD pattern of CdIn2S4 prepared by solvothermal method
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38 Next Plans 1To investigate the influence of other electron acceptor such as Fe 3+ and its concentration on the activity of CdO system. 2To explore how the different loading species with varying amount will influence the O 2 evolution. 3To synthesize Cr or Ni doped CdO to enhance the position of VB of CdO. 4To synthesize other sulfide with better activity.
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