Chinese Journal of Catalysis ›› 2013, Vol. 34 ›› Issue (11): 2036-2040.DOI: 10.1016/S1872-2067(12)60702-5

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Time-resolved infrared spectroscopic investigation of roles of valence states of Cr in (La, Cr)-doped SrTiO3 photocatalysts

Shuai Shena,b, Yushuai Jiaa,b, Fengtao Fana, Zhaochi Fenga, Can Lia   

  1. a State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, Dalian 116023, Liaoning, China;
    b University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2013-07-07 Revised:2013-09-03 Online:2013-10-18 Published:2013-10-18
  • Contact: Zhaochi Feng,Can Li
  • Supported by:

    This work was financially supported by the National Natural Science Foundation of China (21090341, 21173213) and the National Basic Research Program of China (973 Program, 2009CB220010, 2009CB623507).

Abstract:

The kinetics of photogenerated electrons in SrTiO3(La,Cr) pretreated with either H2 or O2 were studied using time-resolved infrared spectroscopy. The X-ray photoelectron and Raman spectra showed that the Cr cations in the sample reduced with H2 were all in Cr3+, whereas those oxidized with O2 were in mixed of Cr3+ and Cr6+. Electrons excited with 355 and 532 nm light pulses showed the absorption of mid-IR light, and this was traced as a function of the time delay in a microsecond domain. The time-resolved results revealed that the decay rate of the photoinduced electrons with Cr3+ was slower than that with Cr6+, implying that trivalent Cr contributed more to retarding recombination of photoinduced electrons and holes, and enhanced photocatalytic H2 production activity.

Key words: Time-resolved spectroscopy, Chromium doping, Strontium titanate, Photocatalysis