Pulsed Laser Deposited Delafossite CuFeO2 for Solar Water Splitting
Raphael Präg a, Moritz Kölbach a
a Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-    Meitner-Platz 1, 14109 Berlin, Germany
nanoGe Fall Meeting
Proceedings of nanoGe Fall Meeting19 (NGFM19)
#SolFuel19. Solar Fuel Synthesis: From Bio-inspired Catalysis to Devices
Berlin, Germany, 2019 November 3rd - 8th
Organizers: Roel van de Krol and Erwin Reisner
Poster, Raphael Präg, 433
Publication date: 18th July 2019

The finding of new photoelectrode materials is one of the major challenges on the way to an cost effective solar fuel production via photoelectrochemical water splitting.

P-type delafossite CuFeO­2 is a potential earth abundant and nontoxic candidate. It has recently gained attention as cathode material for photoelectrochemical water reduction, mainly due to its favorable bandgap of 1.4-1.6 eV and its adequate flat band potential of ~1V vs RHE [5]. The reported theoretical current density limit of 14.8 mA/cm2 in a tandem cell configuration and its stability under aqueous operation conditions motivates further work, in order to overcome its low efficiencies [3,4].

So far, several limiting mechanisms have been proposed by literature, such as fast self-trapping of photo-generated free carriers in the bulk as well as trapping by surface states formed by metal hydroxide groups [2-4].

In order to gain new insights on these limiting factors, the objective of the current work is the synthesis of phase pure CuFeO2 thinfilms and later the application of additional surface passivation layers by pulsed laser deposition (PLD). To obtain such films, stoichiometric target to substrate transfer is crucial. Two different approaches for the deposition of photoactive CuFeO2 are compared.  Alternating between two targets, namely Cu2O and FeO2 provides easy Cu:Fe ratio control, but suffers from Cu2O  droplet formation so far. The CuFeO2 target approach on the other hand, overcomes this issue, but finding the optimal process parameters is more challenging, however still leads to phase pure films. The films are investigated by means of ICP-OES, XRF, XRD and Raman spectroscopy. Finally the photoelectrochemical performance is tested under AM 1.5g Illumination.

The presented work elucidates the influence of fundamental PLD process parameters towards phase purity and performance. It gives therefore important insights on the PLD process of CuFeO2 and its further possibilities as photocathode absorber.

© Fundació Scito
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