ELECTROCHEMICAL NANOFABRICATIONS: A GENERAL REVIEW - Electrochemical Nanofabrication: Principles and Applications - page 33

nanotubes synthesized by electrochemical anodization can be
controlled, and is shown in Fig. 1. 15 .

nanotubes prepared in (A) 0.1 M HF acid
solution at 20 V (B) 1.0 M NaHSO
4

Figure 1.15 SEM images of TiO

2

containing 0.1 M KF at 20 V and (C)
ethylene glycol containing 0.25% NH F at 60 V for 1 h [156]. Reproduced by

4

kind permission from the publisher.

nanotube arrays produced by
electrochemical anodization have been used in DSSCs. It suggests
superior electron transport in nanotubular TiO
2

Highly ordered transparent TiO

2

based DSSCs
[163]. Remarkable photoconversion efficiencies were expected
to be obtained with increase in the length of the nanotube arrays.
Carboxylated polythiophene derivatives can be self-assembled onto
the TiO
2

arrays produced by anodizing titanium foils in ethylene-
glycol-based electrolytes [164]. Such self-assembled hybrid

nanotube array heterojunction solar cells can yield
power efficiency of 2.1% under AM 1.5 without dyes. It was found
that the formation mechanism of TiO

polymer-TiO

2

nanotubes is similar to the
porous alumina case under high electrical field. TiO

2

nanotube
arrays can be fabricated by anodic oxidation of titanium foil in

2