Transparent hematite blocking layer improves the quality of solid||liquid interface on
hematite based solar fuel cells.
R. Milan
a,*
, S. Cattarin
b
, N. Comisso
b
, C. Baratto
a
, G. Sberveglieri
a
, I. Concina
a,c
a
Department of Information Engineering, University of Brescia, Via Valotti, 9 – 25131 and
CNR-INO SENSOR Laboratory, via Branze 45 – 25123 Brescia, Italy
b
ICMATE – CNR, Corso Stati Uniti 4, 35127 Padova, Italy
c
Department of Engineering Sciences and Mathematics, Luleå University of Technology, 971
87 Luleå, Sweden
Fabrication of efficient anodes for photoelectrochemical water splitting calls not only for
functional materials but also for strategies of electrode engineering able to reduce
photogenerated charge losses at relevant interfaces.
1
This lecture focuses on the spray
deposition on conducting glass of a thin, compact and transparent hematite buffer layer (BL),
prior to the formation of vertically aligned hematite nanorods,
2
aimed at engineering a
photoanode for photoelectrochemical water oxidation.
Presence of hematite BL is effective in significantly reducing undesired losses of
photogenerated charges at the FTO||electrolyte interface, one of the most critical in electrodes
of photoelectrochemical cells. Hematite BL is indeed inserted in between the FTO and the
active α-Fe
2
O
3
layer to physically insulate the FTO from the electrolyte, a strategy already
proved highly beneficial in electrodes for excitonic solar cells.
3
The electrode featuring the
hematite BL showed a photo-current about twice larger than that obtained in the absence of
BL. Neither thermal nor doping treatment has been carried out and the use of hematite as BL
eliminates any chance of self-doping, thus supporting that functional performance
enhancement actually relates to elimination of charge losses at FTO||electrolyte. Simple,
green and scalable fabrication techniques are exploited for electrode assembly, which
promise to open the path for an actual improvement of performances of hematite-based
anodes for water oxidation. A detailed physical and functional characterization of the
engineered electrode will be presented and discussed.
References
1.
Sivula, K., Le Formal, F. & Grätzel, M. Solar water splitting: Progress using hematite
(α-Fe 2O3) photoelectrodes.
ChemSusChem
4,
432–449 (2011).
2.
Beermann, N., Vayssieres, L., Lindquist, S.-E. & Hagfeldt, A. Photoelectrochemical
Studies of Oriented Nanorod Thin Films of Hematite.
J. Electrochem. Soc.
147,
2456–
2461 (2000).
3.
Selopal, G. S.
et al.
Effect of blocking layer to boost photoconversion efficiency in
ZnO dye-sensitized solar cells.
ACS Appl. Mater. Interfaces
6,
11236–11244 (2014).
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