Toward electronically coupled bio-inorganic conjugates

D. J. Gosztola*, Z. Saponjic, L. X. Chen, N. M. Dimitrijevic, L. De La Garza, T. Rajh

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Spectroelectrochemical studies of nanocrystalline TiO 2 films on conductive ITO substrates were performed in conjunction with X-ray absorption spectroscopy studies (XANES, XAFS). Electrochemical reduction of nanocrystalline films in the potential range -0.4 V to -1.9 V (vs. Ag/Ag +) led to the reversible changes in UV-vis absorption of titania films along with the change of Ti K-edge associated with the change of the oxidation state Ti 4+/Ti 3+. Additionally, reduction of Ti 4+ to Ti 3+ was accompanied by the change of pre-edge structure of Ti K-edge indicative of the adjustment of the symmetry of Ti sites. The effect of chemical modification of surface Ti atoms on the optical and structural properties was used to differentiate surface and bulk contributions. At high charging potentials, a spectrum characteristic of shallow or free carriers changes and a new localized trapping site was observed that did not change with surface modification. The intensity of this signal increases with the number of injected electrons suggesting that the additional charges are localizing on the existing electron trapping sites causing deeper distortions. The absorption increase and a spectral shift were found to be a slow processes occurring on a second time scale, indicative of a processes accompanied by structural deformation.

Original languageEnglish (US)
Title of host publicationElectron Transfer in Nanomaterials - Proceedings of the International Symposium
Pages350-360
Number of pages11
VolumePV 2004-22
StatePublished - Oct 16 2006
Event205th Electrochemical Society Meeting - San Antonio, TX, United States
Duration: May 9 2004May 14 2004

Other

Other205th Electrochemical Society Meeting
CountryUnited States
CitySan Antonio, TX
Period5/9/045/14/04

ASJC Scopus subject areas

  • Engineering(all)

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