Metal Oxide Nanosurfaces and Hetero-interfaces for Solar Harvesting Applications
Sanjay Mathur*, Yakup Gönüllü, Thomas Fischer and Robert Frohnhoven
*Chair, Inorganic and Materials Chemistry, Department of Chemistry
University of Cologne
Greinstr. 6, Cologne D 50859, Germany
E-mail:
Metal oxide nanostructures with hetero-contacts and phase boundaries offer unique platform
for designing materials architectures for solar harvesting applications. Besides the size and
surface effects, the modulation of electronic behavior due to junction properties leads to
modify surface states that promote higher efficiency. The growing possibilities of engineering
nanostructures in various compositions (pure, doped, composites, heterostructures) and forms
(particles, tubes, wires, films) has intensified the research on the integration of different
functional material units in a single architecture to obtain new materials for solar energy
harvesting application. However, metal oxide nanostructures need a conductive substrate for
electron transfer. Moreover, the substrate should be transparent in order to harvest more light.
Therefore, flexible devices transparent conductive electrodes from wet processed metal
nanowire or nanofibre networks became a promising alternative to high vacuum deposited
brittle ITO or FTO layers.
In this work we present the deposition and modification of semiconducting metal oxides and
their multilayers (TiO
2
, Fe
2
O
3
and TiO
2
/Fe
2
O
3
) for photoelectrochemical (PEC) hydrogen
production. The deposition parameters for thin film creation were optimized with respect to
the PEC performance of the resulting materials in both alkali solution and simulated
seawater. The long-term performances of the metal oxide photoanodes were determined in
alkali and seawater electrolyte, as well. The results presented that the multilayered
TiO
2
/Fe
2
O
3
photonanode yielded higher photocurrent density (1.8 mAcm
-2
at 1.23 V) with
very stable conditions even after 1-week measurement. Moreover, a TCM from silver
nanowires with a diameter of 80 nm and a lenght of 5 µm (aspect ratio of 62.5) were
suggested as alternative substrate.
P 5
-70-
