jp311068m_si_001.pdf (2.61 MB)
Improving the Photoelectrochemical Response of TiO2 Nanotubes upon Decoration with Quantum-Sized Anatase Nanowires
journal contribution
posted on 2016-02-19, 20:59 authored by Milena Jankulovska, Irene Barceló, Teresa Lana-Villarreal, Roberto GómezTiO2 nanotubes (NTs) have been widely used
for a number
of applications including solar cells, photo(electro)chromic devices,
and photocatalysis. Their quasi-one-dimensional morphology has the
advantage of a fast electron transport although they have a relatively
reduced interfacial area compared with nanoparticulate films. In this
study, vertically oriented, smooth TiO2 NT arrays fabricated
by anodization are decorated with ultrathin anatase nanowires (NWs).
This facile modification, performed by chemical bath deposition, allows
to create an advantageous self-organized structure that exhibits remarkable
properties. On one hand, the huge increase in the electroactive interfacial
area induces an improvement by 1 order of magnitude in the charge
accumulation capacity. On the other hand, the modified NT arrays display
larger photocurrents for water and oxalic acid oxidation than bare
NTs. Their particular morphology enables a fast transfer of photogenerated
holes but also efficient mass and electron transport. The importance
of a proper band energy alignment for electron transfer from the NWs
to the NTs is evidenced by comparing the behavior of these electrodes
with that of NTs modified with rutile NWs. The NT-NW self-organized
architecture allows for a precise design and control of the interfacial
surface area, providing a material with particularly attractive properties
for the applications mentioned above.