Charge Carrier Dynamics in Undoped and N-Doped Titania Nanolayers upon Ultraviolet and Visible Light Irradiation

  • This paper reports on the successful synthesis of visible light photoactive N–TiO2 nanolayers and the investigation of charge carrier dynamics in dependence on N-doping and irradiation wavelengths. Grazing incidence X-ray diffractometry exhibited that N-doping supports the formation of an anatase phase with a higher crystallinity than observed for undoped TiO2. Photoelectrochemical measurements gave evidence that N–TiO2 is characterized by a significantly higher incident photon conversion efficiency (IPCE) upon both UV and visible light irradiation. Photoelectrochemical impedance spectroscopy revealed that the higher IPCE of N–TiO2 in UV can be explained by a lowered charge transfer resistance, probably due to its higher crystallinity. The higher photoactivity in the visible can be explained by the incorporation of intrabandgap states upon N-doping. This is supported by X-ray photoelectron spectroscopy indicating the incorporation of N atoms in the titania layer, the observed bandgap narrowing by at least 250 meV as measured byThis paper reports on the successful synthesis of visible light photoactive N–TiO2 nanolayers and the investigation of charge carrier dynamics in dependence on N-doping and irradiation wavelengths. Grazing incidence X-ray diffractometry exhibited that N-doping supports the formation of an anatase phase with a higher crystallinity than observed for undoped TiO2. Photoelectrochemical measurements gave evidence that N–TiO2 is characterized by a significantly higher incident photon conversion efficiency (IPCE) upon both UV and visible light irradiation. Photoelectrochemical impedance spectroscopy revealed that the higher IPCE of N–TiO2 in UV can be explained by a lowered charge transfer resistance, probably due to its higher crystallinity. The higher photoactivity in the visible can be explained by the incorporation of intrabandgap states upon N-doping. This is supported by X-ray photoelectron spectroscopy indicating the incorporation of N atoms in the titania layer, the observed bandgap narrowing by at least 250 meV as measured by ultraviolet–visible absorption spectroscopy, and the decrease of the work function by 50 meV, as derived from scanning Kelvin probe microscopy. Intensity-modulated photocurrent/photovoltage spectroscopy proved that the generally lower quantum yield at visible light is caused not only by the generation of less photoexcited charge carriers, but also by a higher surface hole recombination rate and hence lower hole charge transport efficiency.show moreshow less

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Metadaten
Author:Volker Seiß, Dominik EitelORCiD, Uta Helbig, Maik EichelbaumORCiD
DOI:https://doi.org/10.1021/acs.jpcc.4c01954
ISSN:1932-7447
Parent Title (English):The Journal of Physical Chemistry C
Publisher:American Chemical Society (ACS)
Document Type:Article
Language:English
Reviewed:Begutachtet/Reviewed
Release Date:2024/08/07
Volume:128
Issue:28
Pagenumber:13
First Page:11845
Last Page:11857
institutes:Fakultät Werkstofftechnik
Institut für Angewandte Wasserstoffforschung, Elektro- und Thermochemische Energiesysteme (H2Ohm)
Institut für Chemie, Material- und Produktentwicklung
Fakultät für Angewandte Chemie
Research Themes:Energie & Ressourcen
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