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Annealing effects on the photoresponse of TiO 2 nanotubes
Author(s) -
Ghicov Andrei,
Tsuchiya Hiroaki,
Macak Jan M.,
Schmuki Patrik
Publication year - 2006
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200622041
Subject(s) - annealing (glass) , photocurrent , anatase , materials science , amorphous solid , nanotube , chemical engineering , vacancy defect , photoconductivity , nanotechnology , optoelectronics , composite material , carbon nanotube , chemistry , crystallography , catalysis , photocatalysis , organic chemistry , engineering
The present work investigates the influence of different annealing treatments on the photoresponse of electrochemically formed TiO 2 nanotubes. The “as prepared” TiO 2 nanotube layers have an amorphous structure and show a comparably low photocurrent magnitude. Annealing the tubes in air or dry Ar at 450 °C converts the structure to anatase and increases strongly the photocurrent conversion efficiencies. Significant differences between annealing in air and in dry Ar were found. Annealing in Ar results in green layers that show lower photon to current efficiencies than the layers annealed in air. Extended annealing in Ar at 450 °C leads to morphological changes of the nanotube structure. These differences in the behaviour (photoresponse and mechanical stability) are attributed to the reductive nature of the Ar environment (leading to a partial reduction and vacancy formation). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)