A Charge‐Separated State that Lives for Almost a Second at a Conductive Metal Oxide Interface

Sampaio, Renato N.; Troian‐Gautier, Ludovic; Meyer, Gerald J.

doi:10.1002/ange.201807627

Cited by 16 publications

(24 citation statements)

References 36 publications

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“…4 and 5, an important role for an electron transfer mediator also appears in the design of artificial assemblies. Addition of the Donor +/0 couple as an electron transfer relay between the primary donor (Chrom) and catalyst increases the timescale for back electron transfer from the electrode to holes in the assembly (14,27,28). This enhances the likelihood of performing water oxidation catalysis before charge recombination occurs at Eq.…”

Section: [6]mentioning

confidence: 99%

A stable dye-sensitized photoelectrosynthesis cell mediated by a NiO overlayer for water oxidation

Wang

Niu

Mortelliti

et al. 2019

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

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In the development of photoelectrochemical cells for water splitting or CO2reduction, a major challenge is O2evolution at photoelectrodes that, in behavior, mimic photosystem II. At an appropriate semiconductor electrode, a water oxidation catalyst must be integrated with a visible light absorber in a stable half-cell configuration. Here, we describe an electrode consisting of a light absorber, an intermediate electron donor layer, and a water oxidation catalyst for sustained light driven water oxidation catalysis. In assembling the electrode on nanoparticle SnO2/TiO2electrodes, a Ru(II) polypyridyl complex was used as the light absorber, NiO was deposited as an overlayer, and a Ru(II) 2,2′-bipyridine-6,6′-dicarboxylate complex as the water oxidation catalyst. In the final electrode, addition of the NiO overlayer enhanced performance toward water oxidation with the final electrode operating with a 1.1 mA/cm2photocurrent density for 2 h without decomposition under one sun illumination in a pH 4.65 solution. We attribute the enhanced performance to the role of NiO as an electron transfer mediator between the light absorber and the catalyst.

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Section: [6]mentioning

confidence: 99%

A stable dye-sensitized photoelectrosynthesis cell mediated by a NiO overlayer for water oxidation

Wang

Niu

Mortelliti

et al. 2019

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

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“…The use of ITO as a photoelectrode has historically had limited success. , Injection from sensitizer excited states has been reported, ,,, but it is often followed by rapid and detrimental reduction of the oxidized sensitizer by the conductive oxide. Recent studies have, however, successfully slowed recombination through control of the sensitizer surface orientation. − , Furthermore, the high conductivity has enabled direct measure of the reorganization energy for interfacial electron and proton-coupled electron transfer reactions. ,, These examples encourage the continued and increased use of ITO as a photoelectrode and prompt studies into the fundamental reactivity of dye-sensitized ITO interfaces.…”

Section: Introductionmentioning

confidence: 99%

Factors that Control the Direction of Excited-State Electron Transfer at Dye-Sensitized Oxide Interfaces

Bangle

Meyer

2019

J. Phys. Chem. C

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Molecular excited states at conductive and semiconductive interfaces were found to transfer an electron to the oxide (injection) or accept an electron from the oxide (hole transfer). The direction of this electron transfer was determined by the energetic overlap of the metal oxide and sensitizer redox-active states and their electronic coupling. Potentiostatically controlled mesoporous thin films based on a nanocrystalline conductive metal oxide [tin-doped indium oxide (ITO)] and semiconducting metal oxides (TiO2 and SnO2) were utilized with the sensitizers (S) [Ru(bpy)2(P)]Br2 and [Ru(bpz)2(P)]Br2, where bpy is 2,2′-bipyridine, bpz is 2,2′-bipyrazine, and P is 2,2′-bipyridyl-4,4′-diphosphonic acid. For dye-sensitized TiO2, excited-state injection [TiO2|S* → TiO2(e–)|S+] was exclusively observed, and the injection yield decreased at negative applied potentials. In contrast, evidence for both injection [ITO|S* → ITO(e–)|S+] and hole transfer ([ITO|S* → ITO(h+)|S–] is reported for ITO and SnO2. Hole transfer became more efficient with negative applied potentials. The direction of electron flow between the metal oxide and excited state sensitizer was correlated with the energetic overlap and the electronic coupling as predicted by Marcus−Gerischer theory. The data reveal that control of the Fermi level enables conductive oxides to function as a photocathode or as a photoanode for solar energy conversion applications.

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“…1−3 For example, in artificial photosynthesis, the efficient use of sunlight requires the suitable photogenerated ICT states to yield applicable photocurrent. 4,5 For dye-sensitized organic solar cells, the ICT state can provide the driving force of the electron transfer. 6 Molecules with electronic donor−acceptor (D−A) structures are widely used for ICT study.…”

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confidence: 99%

Through-Space Conjugation: An Effective Strategy for Stabilizing Intramolecular Charge-Transfer States

Shen

Zhuang

Jiang

et al. 2019

J. Phys. Chem. Lett.

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Intramolecular charge transfer (ICT) has significant impacts on organic optoelectronic materials, photochemistry, biotechnology, and so on. However, it is hard to stabilize the ICT state because of the rapid nonradiative charge recombination process, which often quenches light emission. In this work, we use new foldamers of the protonated pyridine-modified tetraphenylethene derivatives that possess through-space conjugation (TSC) characters as the models to study the impact of TSC on the ICT state. Steady and transient spectroscopies illustrate that the lifetime of the ICT state in the molecule with strong TSC can be much longer than those of molecules without TSC, giving rise to a higher fluorescence quantum yield. By combining the theoretical calculations, we demonstrate that the strong TSC can stabilize the ICT state and slow the charge recombination rate by more efficiently dispersing charges. This is a conceptually new design strategy for functional optoelectronic materials that require more stable ICT states.

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A Charge‐Separated State that Lives for Almost a Second at a Conductive Metal Oxide Interface

Cited by 16 publications

References 36 publications

A stable dye-sensitized photoelectrosynthesis cell mediated by a NiO overlayer for water oxidation

A stable dye-sensitized photoelectrosynthesis cell mediated by a NiO overlayer for water oxidation

Factors that Control the Direction of Excited-State Electron Transfer at Dye-Sensitized Oxide Interfaces

Through-Space Conjugation: An Effective Strategy for Stabilizing Intramolecular Charge-Transfer States

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