Res. Chem. Intermed.
, Vol. 31, No. 4–6, pp. 275–283 (2005)
Also available online - www.vsppub.com
Photoelectrochemical characterization of TiO
derived from commercial sol solution for cathodic
and TADASHI SHINOHARA
Materials Life Time Estimation Group, Materials Engineering Laboratory, National Institute for
Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan
Received 3 February 2004; accepted 9 April 2004
Abstract—Preliminary photoelectrochemical characterization of TiO
coatings made using a com-
mercial sol solution on indium–tin oxide glass substrates was carried out under aerated conditions.
The sample with TiO
coating without heat treatment yielded the most negative open-circuit poten-
tial on ultraviolet illumination, while the 400
C heat-treated sample gave the maximum photocurrent.
Both properties are desirable for photocathodic protection applications. A TiO
coating, when directly
applied on copper plate and processed under similar conditions as that of ITO, however, showed p-type
behavior on ultraviolet illumination though a copper plate electrically coupled to ITO glass coated with
showed lowering of electrode potential on ultraviolet illumination. The reasons for the above
observations are discussed.
coatings; photoelectrochemistry; non-sacriﬁcial cathodic protection; photopotential;
Ever since the discovery of the photoassisted splitting of H
photo-aided applications of TiO
have been on the increase. The review arti-
cle by Fujishima et al. gives a detailed description of these appplications .
One interesting use of TiO
thin ﬁlms is its ability to render a non-sacriﬁcial ca-
thodic protection under ultraviolet (UV) illumination to certain metals on which it
is coated. The fundamental principle is that TiO
, being an n-type semiconduc-
tor, has electrons as the majority charge carriers and when it is illuminated by a
light having energy equal to or greater than its band-gap (E
= 3.2 eV), electron–
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