A visible light water-splitting cell with a photoanode formed by codeposition of a high-potential porphyrin and an iridium water-oxidation catalyst

Moore, Gary F.; Blakemore, James D.; Milot, Rebecca L.; Hull, Jonathan F.; Song, Hyunwook; Cai, Lawrence; Schmuttenmaer, Charles A.; Crabtree, Robert H.; Brudvig, Gary W.

doi:10.1039/c1ee01037a

Cited by 264 publications

(272 citation statements)

References 38 publications

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“…Several lines of evidence argue for photoelectrochemical stability and authentic water oxidation activity. First, as noted above, irreversibility of porphyrins on TiO 2 has been previously observed (20). Also, we have observed that films of [Ru(bpy) 2 (4,4′-(PO 3 H 2 ) 2 bpy)] with poor hole transport characteristics also exhibit electrochemical irreversibility on TiO 2 (33).…”

Section: Discussionsupporting

confidence: 51%

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Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

Swierk¹,

Méndez-Hernández

McCool³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

135

107

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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.

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Section: Discussionsupporting

confidence: 51%

“…S2). On TiO 2 the oxidation of the sensitizers was electrochemically irreversible, as previously reported (20). The trends in E pa differed from the observed spectral trends.…”

Section: Resultscontrasting

confidence: 44%

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

Swierk¹,

Méndez-Hernández

McCool³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

135

107

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“…[13][14][15] In the last decade several systems have been proposed employing either metal oxide nanoparticles 8,[16][17][18][19][20][21][22][23][24] or molecular complexes 8,[25][26][27][28] as water oxidation catalyst (WOC). Furthermore, the coupling between the WOC, the chromophore and an electron accepting semiconductor into a photoanode has been achieved through co-absorption of both the catalyst and the chromophore 16,[29][30][31][32] or through dye-WOC supramolecular complexes. [33][34][35][36] Acquiring a fundamental understanding of the electron transfer processes and catalytic water oxidation mechanism following light excitation of the photoanode is essential for the design and the optimization of solar fuel cells.…”

Section: Introductionmentioning

confidence: 99%

A Dynamic View of Proton-Coupled Electron Transfer in Photocatalytic Water Splitting

et al. 2016

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“…The latter is problematic because the rate of water oxidation is enhanced by added buffer bases, conditions that also enhance the rate of water oxidation (5,(17)(18)(19)(20)(21)(22)(23)(24).…”

mentioning

confidence: 99%

Visible photoelectrochemical water splitting into H ₂ and O ₂ in a dye-sensitized photoelectrosynthesis cell

Alibabaei

Sherman

Norris

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

137

163

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A hybrid strategy for solar water splitting is exploited here based on a dye-sensitized photoelectrosynthesis cell (DSPEC) with a mesoporous SnO 2 /TiO 2 core/shell nanostructured electrode derivatized with a surface-bound Ru(II) polypyridyl-based chromophore-catalyst assembly. The assembly, [(4, H 2 ) 2 bpy) 2 Ru(4-Mebpy-4'-bimpy)Ru (tpy) (OH 2 dye-sensitized photoelectrosynthesis cell | water oxidation | core/shell A lthough promising, significant challenges remain in the search for successful strategies for artificial photosynthesis by water splitting into oxygen and hydrogen or reduction of CO 2 to reduced forms of carbon (1-5). In a dye-sensitized photoelectrosynthesis cell (DSPEC), a wide band gap, nanoparticle oxide film, typically TiO 2 , is derivatized with a surface-bound molecular assembly or assemblies for light absorption and catalysis (6-8). In a DSPEC, visible light is absorbed by a chromophore, initiating a series of events that culminate in water splitting: injection, intraassembly electron transfer, catalyst activation, and electron transfer to a cathode or photocathode for H 2 production. Sun and coworkers have recently demonstrated visible-light-driven water splitting with a coloading approach combining Ru(II) polypyridyl-based light absorbers and catalysts on TiO 2 (9). The efficiency of DSPEC devices is dependent on interfacial dynamics and competing kinetic processes. A major limiting factor is the requirement for accumulating multiple oxidative equivalents at a catalyst site to meet the 4e − /4H + demands for oxidizing water to dioxygen (2H 2 O -4e − -4H + → O 2 ) in competition with back electron transfer of injected electrons to the oxidized assembly.One approach to achieving structural control of local electron transfer dynamics at the oxide interface in dye-sensitized devices is by use of nanostructured core/shell electrodes (10-12). In this approach, a mesoporous network of nanoparticles is uniformly coated with a thin oxide overlayer prepared by atomic layer deposition (ALD). We have used core/shell electrodes to demonstrate benzyl alcohol dehydrogenation (13). This approach has also been used to enhance the efficiency of dye-sensitized solar cells (14,15). Recently, we described the use of a core/shell consisting of an inner core of a nanoparticle transparent conducting oxide, tin-doped indium oxide (nanoITO), and a thin outer shell of TiO 2 for water splitting by visible light (16 Fig. 1A, provided the basis for a photoanode in a DSPEC application with a Pt cathode for H 2 generation with a small applied bias in an acetate buffer at pH 4.6.Application of the core/shell structure led to a greatly enhanced efficiency for water splitting compared with mesoscopic, nanoparticle TiO 2 but the per-photon absorbed efficiency of the resulting DSPEC was relatively low and problems arose from longterm instability due to loss of the assembly from the oxide surface in the acetate buffer at pH 4.6. The latter is problematic because the rate of water oxidation is enhanced by added buffer bases...

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A visible light water-splitting cell with a photoanode formed by codeposition of a high-potential porphyrin and an iridium water-oxidation catalyst

Cited by 264 publications

References 38 publications

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

A Dynamic View of Proton-Coupled Electron Transfer in Photocatalytic Water Splitting

Visible photoelectrochemical water splitting into H ₂ and O ₂ in a dye-sensitized photoelectrosynthesis cell

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A visible light water-splitting cell with a photoanode formed by codeposition of a high-potential porphyrin and an iridium water-oxidation catalyst

Cited by 264 publications

References 38 publications

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

A Dynamic View of Proton-Coupled Electron Transfer in Photocatalytic Water Splitting

Visible photoelectrochemical water splitting into H 2 and O 2 in a dye-sensitized photoelectrosynthesis cell

Contact Info

Product

Resources

About

Visible photoelectrochemical water splitting into H ₂ and O ₂ in a dye-sensitized photoelectrosynthesis cell