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

☻ 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 CO 2 in air during the past one thousand years Significance of hydrogen energy

4 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 目项 目 合成氨 炼油厂加氢精制 燃料电池电动车 燃料电池发电 合 计

6 Predict hydrogen source in the next fifty years

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

A.Fijishima and K.Honda. Nature. 1972, 238, 37. TiO hv 2 e – +2 h + (1) (at the TiO 2 electrode) 2 H e – H 2 (2) (at the Pt electrode) H 2 O + 2 h + 1/2 O 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

9 Pt H+H2H+H2 hv H2OO2H2OO2 h+h+ e- VB CB RuO 2 Schematic Water oxidation and reduction process over photocatalyst

10 h+h+ e- VB CB H + /H 2 O 2 /H 2 O 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

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

12 Solar energy distribution detected at PM 12 in Japan

13 Vis nm UV <400nm IR >700nm

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

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, Recent development of water splitting

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

17 A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, 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 M Na 2 S 20ml CH 3 OH +180ml H 2 O

18 A. Ishikawa et al, J. Am. Chem. Soc., 2002, 124, Estimated band position of Sm 2 Ti 2 S 2 O 5 at pH = 0 and 8

19 A. Kudo et al, Chem. Comm., 2002, Diffuse reflection spectra of AgInZn 7 S 9 (a), ZnS (b) and AgInS 2 (c). AgInS 2 AgInZn 7 S 9 ZnS

20 A. Kudo et al, Chem. Comm., 2002, 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 M Na 2 S solution 300 ml.

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

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 R =

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

24 Y = 3.18E-4*X R = High yield part (S> ) hydrogen evolution standard curve for S-1 and S-2

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

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

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

28 Photocatalytic O 2 evolution over CdO calcinated at varying temperature(Condition: catalyst 0.5g, 0.01M AgNO 3 200ml)

29 Effect of La 2 O 3 on the activity of the CdO calcinated at 400°C

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)

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)

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

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)

34 Uv-Vis diffuse reflection spectra for CdO prepared at different temperature

35 XRD pattern of CdO calcinated at 360  C

Intensity(a.u.) wavelengthen / nm CdIn2S4 CdS UV-Vis diffuse reflection spectra for CdS and CdIn 2 S 4 prepared by the solvothermal method.

37 XRD pattern of CdIn2S4 prepared by solvothermal method

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.