Homogeneous catalysis of platinum(II) complexes in photochemical hydrogen production from water

Sakai, Ken; Ozawa, Hiroki

doi:10.1016/j.ccr.2007.08.014

Cited by 242 publications

(175 citation statements)

References 69 publications

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“…The suggested sequence of protonation steps is also in agreement with the pK a values for related structures taken from the literature (benzoic acid: pK a = 21.5 in acetonitrile, [27] protonated imidazole ring of chloro (4,4…”

Section: Steady-state Absorption and Protonation Statessupporting

confidence: 88%

“…Many ruthenium polypyridine dyes show a favorable combination of strong absorption of visible light, high stability in several redox states, and often long-lived excited states, [1,2] which makes them ideal candidates for artificial light-harvesting systems, for example, for photocatalytic assemblies [3,4] and dyesensitized solar cells (DSSCs). [5,6] To effectively capture photons, dyes with large extinction coefficients and maximum overlap of the absorption spectrum with the solar radiation spectrum must be designed.…”

Section: Introductionmentioning

confidence: 99%

“…[13][14][15] A carboxyl group at the indicated position should be able to facilitate electronic coupling between both singlet and triplet excited states and the acceptor states of TiO 2 , which is the prerequisite for efficient electron injection. [18] In accordance with these considerations, the complex bis (4,4 Figure 1 A) bearing a carboxyl group in the para position of the phenyl group was synthesized. [26] The present study investigates the impact of the carboxyl group on the excited-state dynamics of Ru1 and how it affects the occurrence of the excited-state planarization.…”

mentioning

confidence: 99%

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Photophysics of a Ruthenium 4H‐Imidazole Panchromatic Dye in Interaction with Titanium Dioxide

et al. 2015

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The photophysics of bis(4,4'-di-tert-butyl-2,2'-bipyridine-κ(2)N,N')[2-(4-carboxyphenyl)-4,5-bis(p-tolylimino-κN)imidazolato]ruthenium(II) hexafluorophosphate is investigated, both in solution and attached to a nanocrystalline TiO2 film. The studied substitution pattern of the 4H-imidazole ligand is observed to block a photoinduced structural reorganization pathway within the 4H-imidazole ligand that has been previously investigated. Protonation at the 4H-imidazole ring decreases the excited-state lifetime in solution. When the unprotonated dye is anchored to TiO2, photoinduced electron injection occurs from thermally nonrelaxed triplet metal-to-ligand charge transfer ((3)MLCT) states with a characteristic time constant of 0.5 ps and an injection efficiency of roughly 25%. Electron injection from the subsequently populated thermalized (3)MLCT state of the dye does not take place. The energy of this state seems to be lower than the conduction band edge of TiO2.

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Section: Steady-state Absorption and Protonation Statessupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Photophysics of a Ruthenium 4H‐Imidazole Panchromatic Dye in Interaction with Titanium Dioxide

et al. 2015

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“…Catalysts made from the noble metals Ru and Ir work quite well for water oxidation, [50,51] and hydrogen formation is accomplished by Pt and Pd. [5] Several of these catalysts could in principle be used for solar fuel production, but due to the scarcity of these elements they are not sustainable or suitable for development on larger scale. Abundant elements for active electron acceptor catalysts are Co, Ni, and Fe [17,22,52] that constitute the active parts in several well functioning systems.…”

Section: Resultsmentioning

confidence: 99%

“…When water is used as starting material, hydrogen is a logical product and there are several recent examples of photochemical hydrogen production. [5][6][7][8] However, the transition to a hydrogen based economy is not straightforward and there are technological hurdles to overcome before hydrogen is used worldwide. An alternative is to use CO 2 from the atmosphere as a second raw material (in addition to water) and make a carbon based solar fuel.…”

Section: Renewable Materials Renewable Energymentioning

confidence: 99%

Molecular Chemistry for Solar Fuels: From Natural to Artificial Photosynthesis

Magnuson¹

2012

Aust. J. Chem.

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The world needs new, environmentally friendly, and renewable fuels to exchange for fossil fuels. The fuel must be made from cheap, abundant, and renewable resources. The research area of solar fuels aims to meet this demand. This paper discusses why we need a solar fuel, and proposes solar energy as the major renewable energy source to feed from. The scientific field concerning artificial photosynthesis is expanding rapidly and most of the different scientific visions for solar fuels are briefly reviewed. Research strategies for the development of artificial photosynthesis to produce solar fuels are overviewed, with some critical concepts discussed in closer detail.

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Hydrogen Production from Water: Photocatalysis

Arachchige

Brewer

2005

Encyclopedia of Inorganic Chemistry

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Photocatalytic hydrogen production from water provides an attractive but challenging approach to meeting our global energy needs. Design and development of systems that utilize visible light to drive the energetically favorable, multielectron reduction of water to produce hydrogen fuel have been of long‐term interest. Addressing the challenges of efficient harvesting of solar energy to produce transportable fuels requires ongoing, sustained research in this field. Current technologies utilize photobiological methods, photoelectrochemical methods, and molecular photocatalysis. This article focuses on the recent progress of proton or water reduction using supramolecular photocatalysts. These photochemical molecular devices often couple charge‐transfer light absorbers (LAs) to reactive metals in complex molecular architectures. Linking multiple components into large molecular assemblies allows for applications requiring complex functions. Early successes in supramolecular photocatalysts for solar hydrogen production are summarized. The redox, excited state properties, and photochemical properties of supramolecular systems applicable in photocatalytic hydrogen production are presented. Fundamental studies of the perturbations of subunit properties upon incorporation into supramolecular arrays are paramount to their successful application in this forum. Optical excitation typically affords a metal‐to‐ligand charge‐transfer state that is quenched by electron transfer, providing reduced complexes with reactive metals able to deliver the electrons to substrates. Sacrificial electron donors provide coupling to oxidative chemistry, allowing independent study of photocatalysts and hydrogen production schemes. Supramolecular chemistry allows modulation of redox, photophysical, and photochemical properties by component modification. Coupling multiple LAs to an electron acceptor, which, when reduced by multiple electrons, provides photoinitiated electron collectors (ECs). Photoinitiated ECs, which collect multiple electrons on a reactive rhodium center with the supramolecular architecture remaining, reduce water to hydrogen fuel. Mixed‐valence systems that promote HX reduction to produce hydrogen have also been described. Coupling of charge‐transfer LAs to cobalt, iron, palladium, or platinum is a topic of recent interest in the design of water reduction photocatalysts. The general design considerations for the development of supramolecular assemblies that function as photocatalysts for proton reduction are discussed, providing valuable insight into engineering efficient solar hydrogen production catalysts for water reduction. Mechanistic studies remain important to understanding this complex multielectron photochemistry, which will aid in future molecular design. Much remains to be mastered in this complicated, multielectron photochemistry but recently there is increased awareness and interest in this field.

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Homogeneous catalysis of platinum(II) complexes in photochemical hydrogen production from water

Cited by 242 publications

References 69 publications

Photophysics of a Ruthenium 4H‐Imidazole Panchromatic Dye in Interaction with Titanium Dioxide

Photophysics of a Ruthenium 4H‐Imidazole Panchromatic Dye in Interaction with Titanium Dioxide

Molecular Chemistry for Solar Fuels: From Natural to Artificial Photosynthesis

Hydrogen Production from Water: Photocatalysis

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