Research on Chemical Intermediates

, Volume 43, Issue 9, pp 5041–5054 | Cite as

Photo-generated conduction-band and shallow-trap electrons from UV irradiation on ethanol-adsorbed TiO2 and N-TiO2: an in situ infrared study

  • Jiawei Liu
  • Long Zhang
  • Xuesi Yao
  • Steven S. C. Chuang


The dynamic behaviors of conduction-band electrons (\({\text{e}}_{CB}^{ - }\)) and shallow-trap electrons (\({\text{e}}_{ST}^{ - }\)) generated from UV irradiation on ethanol-adsorbed TiO2 and N-TiO2 have been studied by in situ Fourier transform infrared spectroscopy (FTIR) in a diffuse reflectance mode at 300 K and 0.1 MPa. UV irradiation on ethanol-adsorbed TiO2 resulted in the breaking of C–H bond of ethanol, the transfer of electrons from ethanol to the photo-generated holes on TiO2 and N-TiO2, the accumulation of \({\text{e}}_{CB}^{ - }\) and \({\text{e}}_{ST}^{ - }\), and the formation of acetate on TiO2 and the formation of acetate, formate, and formaldehyde on N-TiO2. Accumulated \({\text{e}}_{CB}^{ - }\) and \({\text{e}}_{ST}^{ - }\) are manifested by broad and featureless IR absorbance spectra, which can be fitted into two models for estimation of their relative concentrations. N-doping onto TiO2 produced a higher population of \({\text{e}}_{ST}^{ - }\) and generated \({\text{e}}_{ST}^{ - }\) and \({\text{e}}_{CB}^{ - }\) at a lower rate than TiO2. The average energy level of \({\text{e}}_{ST}^{ - }\) was determined to be 0.30 eV for TiO2 and 0.26 eV for N-TiO2 below the conduction band. Upon terminating UV irradiation, the IR intensity of accumulated \({\text{e}}_{CB}^{ - }\) and \({\text{e}}_{ST}^{ - }\) showed a gradual decay in a time scale of minutes. This study demonstrated that the recombination of photo-generated electrons and holes can be a slow process on TiO2 and N-TiO2 in the presence of adsorbed ethanol under ambient conditions.

Graphical Abstract


TiO2 N-doped TiO2 Conduction-band electrons Shallow-trap electrons Adsorbed ethanol FTIR Photocatalysis 



This work was supported by the University of Akron Polymer Science Faculty Initiation Fund. The authors thank Ms. Jie Yu and Mr. P. Patanapaniswa for valuable discussions.


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Copyright information

© Springer Science+Business Media B.V. 2017

Authors and Affiliations

  • Jiawei Liu
    • 1
  • Long Zhang
    • 1
  • Xuesi Yao
    • 1
  • Steven S. C. Chuang
    • 1
  1. 1.Department of Polymer ScienceThe University of AkronAkronUSA

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