title: Direct Light-Driven Water Oxidation by a Ladder-Type Conjugated Polymer Photoanode.
abstract: A 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 (SO3(2-)), 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.
authors.affiliation: Laboratory for Molecular Engineering of Optoelectronic Nanomaterials, École Polytechnique Fédérale de Lausanne (EPFL) , Station 6, 1015 Lausanne, Switzerland.
authors.forename: Pauline
authors.initials: P
authors.lastname: Bornoz
authors.affiliation: Laboratory for Molecular Engineering of Optoelectronic Nanomaterials, École Polytechnique Fédérale de Lausanne (EPFL) , Station 6, 1015 Lausanne, Switzerland.
authors.forename: Mathieu S
authors.initials: MS
authors.lastname: Prévot
authors.affiliation: Laboratory for Molecular Engineering of Optoelectronic Nanomaterials, École Polytechnique Fédérale de Lausanne (EPFL) , Station 6, 1015 Lausanne, Switzerland.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Yu
authors.affiliation: Laboratory for Molecular Engineering of Optoelectronic Nanomaterials, École Polytechnique Fédérale de Lausanne (EPFL) , Station 6, 1015 Lausanne, Switzerland.
authors.forename: Néstor
authors.initials: N
authors.lastname: Guijarro
authors.affiliation: Laboratory for Molecular Engineering of Optoelectronic Nanomaterials, École Polytechnique Fédérale de Lausanne (EPFL) , Station 6, 1015 Lausanne, Switzerland.
authors.forename: Kevin
authors.initials: K
authors.lastname: Sivula