The NANEL joint exchange project aims in establishment of long-lasting research
cooperation between Portuguese, Bulgarian, Belgian, Belarusian and Russian scientists in
the field of electrochemical synthesis of advanced nanostructured materials. The
collaborative consortium joins together a critical mass of the expertise available in the
involved groups. The partners bring the complementary experiences and experimental
facilities which are essential for effective development and testing of the nanomaterials to
be applied in sensors and photovoltaics. Mutually beneficial transfer of knowledge will be
implemented through an intensive exchange program between six partner organizations
involved in the consortium.
The main technical objective of the project is the development of novel functional
nanomaterials for sensors and solar cell applications on the basis of ordered nanoporous
anodic oxides. The main scientific novelty of the project is the functionalization of the
porous anodic oxides, such as alumina or titania, via electrochemical or electrophoretic
ways using non-aqueous electrolytes. Ionic liquids and near room-temperature molten salts
will be used as prospective candidates for such electrolytes. The electrochemical synthesis
of nanomaterials has several important advantages because of its relatively low cost and
fine tuning of the process parameters. The suggested approach will confer creation of new
ordered functional nanomaterials via electrochemical routes which have not been possible
in water-based electrolytes. Use of non-aqueous solutions presents significant advantages
for specific materials which are not stable in presence of water or can not be
electrodeposited because of the relatively narrow electrochemical window of water.
The work program of NANEL project intends to synergistically unite the specific
complementary expertise of the involved partners. These experiences cover all the needed
steps from formation of the nanoporous ordered templates and deep knowledge on the
mechanisms of electrochemical processes to electrodeposition from non-aqueous
electrolytes and testing of the developed materials towards applications in photovoltaics
and novel sensors.
During the first phase of the NANEL project significant steps towards the achievement of
the main objectives were made. The progress was achieved in all the complementary
directions. The ordered porous oxide templates on Ti and Al surface were prepared and
studied in detail. The geometrical factor of the pores was optimized in order to ensure that
the templates are suitable for further electrodeposition of functional nanomaterials.
Additionally two different approaches were used to prepare porous templates on the surface
of silicon. The porous silicon was obtained by the etching of heavy ion tracks and by using
electrochemical etching techniques with silver ions. The mechanistic details of the latest
process were also investigated in detail demonstrating an important role of silver silicate
formation on the self-limitation of the pore growth.
Another important activity was focused on deeper understanding of the initial stages of the
nucleation of nano-phases during early stages of electrodeposition. The new
Electrochemical Aggregative Growth Mechanism was proposed.
The core task of NANEL is electodeposition of functional nanomaterials in the porous
templates. The possibility to deposit metallic materials into both titania and alumina was
demonstrated for the first time as shown in the SEM micrograph.
SEM micrograph of porous ordered TiO2 filled by metal via electrodeposition from ionic
liquid.
However the electrodeposition process is still has to be optimized since full filling of the
pores was not yet achieved in both cases. In the case of alumina based templates with
barrier layer the electrodeposition occurs on the bottom of pores only in some local zones
while the filling of the pores from the top happens when titania templates are employed.
The activities on creation of novel solar cells and sensors on the basis of the developed
materials were also actively performed. The magnetic oxide nanoparticles were synthesized
as well as mixed sulfide compounds for sensors and solar cells respectively. At the next
stage of the project these functional materials will be electrophoretically deposited into the
porous templates.
The project has resulted in publication of 8 papers and presentation on number of important
international conferences. Moreover active training and dissemination activities on
institutional level were performed including one joint workshop organized together with
two other IRSES projects. This allowed establishing even deeper networking between the
researchers from 6 different countries.