title: Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells.
abstract: Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ > 590 nm) illumination in a dye-sensitized TiO2 solar cell. We report the synthesis, spectral, and electrochemical properties of the sensitizers. Despite slow recombination of photoinjected electrons with oxidized porphyrins, photocurrents are low because of low injection yields and slow electron self-exchange between oxidized porphyrins. The free-base porphyrins are stable under conditions of water photoelectrolysis and in some cases photovoltages in excess of 1 V are observed.
authors.affiliation: Departments of Chemistry and.
authors.forename: John R
authors.initials: JR
authors.lastname: Swierk
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: Dalvin D
authors.initials: DD
authors.lastname: Méndez-Hernández
authors.affiliation: Departments of Chemistry and.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: McCool
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: Paul
authors.initials: P
authors.lastname: Liddell
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Terazono
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: Ian
authors.initials: I
authors.lastname: Pahk
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: John J
authors.initials: JJ
authors.lastname: Tomlin
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: Nolan V
authors.initials: NV
authors.lastname: Oster
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Moore
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Moore
authors.affiliation: Department of Chemistry and Biochemistry and Center for Bio-Inspired Solar Fuel Production, Arizona State University, Tempe, AZ 85287.
authors.forename: Devens
authors.initials: D
authors.lastname: Gust
authors.affiliation: Departments of Chemistry and Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802; and tem5@psu.edu.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Mallouk
keywords: artificial photosynthesis; metal-free porphyrins; photoelectrochemical; visible light; water-splitting