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Download fileDirect Light-Driven Water Oxidation by a Ladder-Type Conjugated Polymer Photoanode
journal contribution
posted on 2015-12-09, 06:59 authored by Pauline Bornoz, Mathieu S. Prévot, Xiaoyun Yu, Néstor Guijarro, Kevin SivulaA conjugated
polymer known for high stability (poly[benzimidazobenzophenanthroline],
coded as BBL) is examined as a photoanode for direct solar water oxidation.
In aqueous electrolyte with a sacrificial hole acceptor (SO32–), photoelectrodes show a morphology-dependent
performance. Films prepared by a dispersion-spray method with a nanostructured
surface (feature size of ∼20 nm) gave photocurrents up to 0.23
± 0.02 mA cm–2 at 1.23 VRHE under
standard simulated solar illumination. Electrochemical impedance spectroscopy
reveals a constant flat-band potential over a wide pH range at +0.31
VNHE. The solar water oxidation photocurrent with bare
BBL electrodes is found to increase with increasing pH, and no evidence
of semiconductor oxidation was observed over a 30 min testing time.
Characterization of the photo-oxidation reaction suggests H2O2 or •OH production with the bare film, while
functionalization of the interface with 1 nm of TiO2 followed
by a nickel–cobalt catalyst gave solar photocurrents of 20–30
μA cm–2, corresponding with O2 evolution.
Limitations to photocurrent production are discussed.