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Assessing the photoelectrochemical properties of C, N, F codoped TiO2 nanotubes of different lengths

Assessing the photoelectrochemical properties of C, N, F codoped TiO2 nanotubes of different lengths

Category
Academic article
Abstract
The aim of this work has been the photoelectrochemical (PEC) study of nanostructured photoanodes based on TiO2. Highly ordered and well adhered TiO2 nanotubes (TNTs) of different lengths (∼2–20 μm) were prepared in a two-step process in ethylene glycol solutions containing fluorides, and detailed XPS analysis showed that they have become co-doped with C, N and F. PEC measurements revealed that increasing surface area is not followed by increase in the photoconversion efficiency, but rather that an optimal balance between electroactive surface area (ESA) and charge carrier concentration exists. TNTs of around 10 μm show the optimum incident photon-to-current efficiency (IPCE) of ∼33% and an overall photoconversion efficiency of ∼6.3% under UV illumination of 4 mW cm−2 light intensity. Finally, Mott-Schottky analysis revealed significant frequency dispersion of the estimated space charge layer capacitance, which renders the accurate estimation of the flatband position and charge carrier concentration unreliable. On the other hand, more realistic charge carrier concentrations can be obtained by normalizing the capacitance per ESA.
Client
  • Research Council of Norway (RCN) / 239211
Language
English
Author(s)
Affiliation
  • University of Oslo
  • SINTEF Industry / Materials and Nanotechnology
  • SINTEF Industry / Sustainable Energy Technology
Year
2017
Published in
Catalysis Today
ISSN
0920-5861
Publisher
Elsevier
Volume
287
Page(s)
161 - 168