Recent Progress of Photocatalytic Water Splitting and Preliminary Work

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

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

4. The funds used for the hydrogen project of USA in the past six years

5. 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 我国未来所需氢的预测结果（万吨）

6. Predict hydrogen source in the next fifty years

7. hv 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 H2 + ½ O2 H2O Photocatalyst •Energy source • Environment • Economy

8. Mechanism of photocatalytic water splitting 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) A.Fijishima and K.Honda. Nature. 1972, 238, 37.

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

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

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

12. Solar energy distribution detected at PM 12 in Japan

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

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

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

16. 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) A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 13547.

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

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

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

20. Photocatalytic H2 evolution over AgInZn7S9(a) and 3wt%-Pt /AgInZn7S9 under visible light irradiation(>420nm, catalyst, 0.3g; 0.25 MK2SO3- 0.35 M Na2S solution 300 ml. A. Kudo et al, Chem. Comm., 2002, 1958.

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

22. Y = 2.60E-4*X+0. 29 R = 0.99676 Low yield part (S<9120) hydrogen evolution standard curve for System-1 and System-2(S-1, S-2)

23. Y = 1.92-4*X+2.31 R = 0.99978 Middle yield part (9120<S<1400000) hydrogen evolution standard curve for S-1 and S-2

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

25. Y = 1.92E-3*X-2.63 R = 0.99951 Oxygen evolution standard curve for S-1 and S-2

26. Y =2.56E-3*X-3.50 R = 0.99951 Nitrogen evolution standard curve for S-1 and S-2

27. CH3OH 30ml, H2O 170ml 0.01M AgNO3 200ml, >420nm Time course of H2(A) and O2(B) evolution over CdO-360 (condition catalyst, 0.5g; 300W xenon lamp)

28. Photocatalytic O2evolution over CdO calcinated at varying temperature(Condition: catalyst 0.5g, 0.01M AgNO3 200ml)

29. Effect of La2O3 on the activity of the CdO calcinated at 400°C

30. CdO-500-la2O3 CdO-400-la2O3 Photocatalytic O2evolution over CdO calcinated at 400 and 500C(Condition: catalyst 0.5g; 0.01M AgNO3 200ml; la2O3, 0.2g)

31. Photocatalytic O2evolution over CdO-400 and 1% RuO2 loadedCdO-400(Condition: catalyst 0.5g; 0.01M AgNO3 200ml; La2O3, 0.2g)

32. R = 11.2mol/h Photocatalytic O2evolution over CdO calcinated at 400°C (Condition: catalyst 0.5g, 0.01M AgNO3 200ml, La2O3 0.2g)

33. Photocatalytic O2evolution over CdO-500 and RuO2 loadedCdO-500(Condition: catalyst 0.5g; 0.01M AgNO3 200ml; La2O3, 0.2g)

34. 360 400 500 Uv-Vis diffuse reflection spectra for CdO prepared at different temperature

35. XRD pattern of CdO calcinated at 360C

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

37. XRD pattern of CdIn2S4 prepared by solvothermal method

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