Direct evidence of catalyst reduction on dye and catalyst co-sensitized NiO photocathodes by mid-infrared transient absorption spectroscopy

Gatty, Mélina Gilbert; Pullen, Sonja; Sheibani, Esmaeil; Tian, Haining; Ott, Sascha; Hammarström, Leif

doi:10.1039/c8sc00990b

Cited by 28 publications

(33 citation statements)

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“…25a). 491,494,500,501 By coordinating a cobaltoxime catalyst to the Ru II dye molecule with a free pyridyl ligand already on a NiO electrode, Wu and co-workers obtained a chromophore-catalyst assembly-immobilized photocathode (Fig. 25b).…”

Section: Molecular-catalyst-modified Dye-sensitized Pec Cells (Dspec mentioning

confidence: 99%

Artificial photosynthesis: opportunities and challenges of molecular catalysts

2019

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Section: Molecular-catalyst-modified Dye-sensitized Pec Cells (Dspec mentioning

confidence: 99%

Artificial photosynthesis: opportunities and challenges of molecular catalysts

2019

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“…38 Co-immobilization of photosensitizers and water reduction catalysts can, in principle, lead to a functioning water reduction system. [39][40][41][42][43][44] A logical extension of the photocatalytic system, which we studied previously in homogeneous solution, [34][35][36][37] would be to combine the system of ref. 38 A specific order of reactions is required for the system to efficiently produce hydrogen, depending on the relative rates of electron transfer and quenching between the reaction partners.…”

Section: Introductionmentioning

confidence: 99%

Shedding Light on the Molecular Surface Assembly at the Nanoscale Level: Dynamics of a Re(I) Carbonyl Photosensitizer with a Coadsorbed Cobalt Tetrapyridyl Water Reduction Catalyst on ZrO₂

et al. 2020

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We present systematic kinetic studies of the interaction of a rhenium-based photosensitizer with a cobalt(II) tetrapyridyl water reduction catalyst coadsorbed on ZrO2 by transient IR and visible spectroscopies. The study focuses on the competition between the reduction of the excited photosensitizer by an electron donor in solution and nonproductive quenching between the photosensitizer and the catalyst, either by Dexter energy transfer or by electron transfer followed by ultrafast geminate recombination. The implications of both interactions for the charge transfer reactions on the surface are investigated. We find that the kinetics of the system as a whole and the achievable yield of reduced photosensitizer are determined by the inhomogeneous distribution of next neighbor distances between photosensitizers and the water reduction catalysts at the nanoscale level. This provides insight for rational design of heterogeneous water splitting systems with coimmobilized photosensitizers and catalysts.

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“…A heterogeneous system, where one or more of the reaction partners are surface-bound, allows for much higher concentrations of the various electron transfer partners than in solution, leading to shorter intermolecular distances, and therefore, to significantly faster charge transfer rates. 21 Since reaction cycles in typical water-splitting systems are controlled kinetically, that might change the overall mechanism completely. For example, the initial step of reductive quenching remains diffusioncontrolled if a sacrificial donor reagent in solution is used.…”

Section: Introductionmentioning

confidence: 99%

Geminate Recombination versus Cage Escape in the Reductive Quenching of a Re(I) Carbonyl Complex on Mesoporous ZrO₂

et al. 2019

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In the wider context of artificial photosynthesis, this work aims to explore the functionality and characteristics of rhenium tricarbonyl complexes as photosensitizers in heterogeneous water reduction systems. To that end, the reductive quenching of an excited ReICl(2,2-bipyridine-4,4-bisphosphonic acid)(CO)3 adsorbed on a redox-neutral scaffold by phenothiazine was observed by transient IR spectroscopy. From the spectroscopic and time response, the full reaction cycle could be elucidated, and the intrinsic lifetime of the excited Re complex, together with rates for reductive quenching, cage escape, as well as geminate recombination and secondary back electron transfer could be determined. Three different scenarios have been explored, which decrease the mobility of the reactants in the system in a stepwise manner: Starting from a reference system with all compounds in solution, first the Re complex was immobilized on the surface, and in a second step also the quencher. The overall reaction cycle for all reactants in solution is preserved as long as the quencher is in solution, with relatively minor changes of the rates of the individual reaction steps. The overall cage escape yield was found to be larger on the surface. As soon as the quencher is co-adsorbed alongside the Re-complex, however, the reaction cycle changes completely. Electron transfer occurred only from quencher molecules that sit next to an excited Re complex, and there is no possibility of cage escape. Varying the ratio of quencher molecules and Re-complexes, it is concluded that molecules do not cluster on the surface, and that excitation energy migration is not a very efficient process.

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Direct evidence of catalyst reduction on dye and catalyst co-sensitized NiO photocathodes by mid-infrared transient absorption spectroscopy

Abstract: Co-sensitization of molecular dyes and catalysts on semiconductor surfaces is a promising strategy to build photoelectrodes for solar fuel production.

Cited by 28 publications

References 27 publications

Artificial photosynthesis: opportunities and challenges of molecular catalysts

Artificial photosynthesis: opportunities and challenges of molecular catalysts

Shedding Light on the Molecular Surface Assembly at the Nanoscale Level: Dynamics of a Re(I) Carbonyl Photosensitizer with a Coadsorbed Cobalt Tetrapyridyl Water Reduction Catalyst on ZrO₂

Geminate Recombination versus Cage Escape in the Reductive Quenching of a Re(I) Carbonyl Complex on Mesoporous ZrO₂

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Direct evidence of catalyst reduction on dye and catalyst co-sensitized NiO photocathodes by mid-infrared transient absorption spectroscopy

Abstract: Co-sensitization of molecular dyes and catalysts on semiconductor surfaces is a promising strategy to build photoelectrodes for solar fuel production.

Cited by 28 publications

References 27 publications

Artificial photosynthesis: opportunities and challenges of molecular catalysts

Artificial photosynthesis: opportunities and challenges of molecular catalysts

Shedding Light on the Molecular Surface Assembly at the Nanoscale Level: Dynamics of a Re(I) Carbonyl Photosensitizer with a Coadsorbed Cobalt Tetrapyridyl Water Reduction Catalyst on ZrO2

Geminate Recombination versus Cage Escape in the Reductive Quenching of a Re(I) Carbonyl Complex on Mesoporous ZrO2

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Shedding Light on the Molecular Surface Assembly at the Nanoscale Level: Dynamics of a Re(I) Carbonyl Photosensitizer with a Coadsorbed Cobalt Tetrapyridyl Water Reduction Catalyst on ZrO₂

Geminate Recombination versus Cage Escape in the Reductive Quenching of a Re(I) Carbonyl Complex on Mesoporous ZrO₂