ChemInform Abstract: EFFICIENT HOMOGENEOUS PHOTOCHEMICAL HYDROGEN GENERATION AND WATER REDUCTION MEDIATED BY COBALOXIME OR MACROCYCLIC COBALT COMPLEXES

Hawecker, Jeannot; Lehn, Jean-Maríe; Ziessel, Raymond

doi:10.1002/chin.198340125

Cited by 36 publications

(55 citation statements)

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“…With a view toward the possible long-term utilization of hydrogen from solardriven water splitting, efforts have expanded over the past decade to use components that contain only earth-abundant elements and thus to remove Pt, Pd, Ru, Ir, and Rh from such systems. In this regard, photochemical proton reduction systems have been reported in which complexes of cobalt, nickel, and iron are found to function as catalysts for hydrogen generation (18,(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41). A number of these complexes were inspired by the active sites of hydrogenase enzymes in which Fe is, and Ni may be, present, and a pendant organic base is thought to help as a proton shuttle to a postulated metal-hydride intermediate for H 2 formation (30,31,35,37,42,43).…”

mentioning

confidence: 99%

Photogeneration of hydrogen from water using CdSe nanocrystals demonstrating the importance of surface exchange

Das

Han

Haghighi

et al. 2013

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

129

139

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Unique tripodal S-donor capping agents with an attached carboxylate are found to bind tightly to the surface of CdSe nanocrystals (NCs), making the latter water soluble. Unlike that in similarly solubilized CdSe NCs with one-sulfur or two-sulfur capping agents, dissociation from the NC surface is greatly reduced. The impact of this behavior is seen in the photochemical generation of H 2 in which the CdSe NCs function as the light absorber with metal complexes in aqueous solution as the H 2 -forming catalyst and ascorbic acid as the electron donor source. This precious-metalfree system for H 2 generation from water using [Co(bdt) 2 ]− (bdt, benzene-1,2-dithiolate) as the catalyst exhibits excellent activity with a quantum yield for H 2 formation of 24% at 520 nm light and durability with >300,000 turnovers relative to catalyst in 60 h.photochemistry | solar energy | catalysis | water splitting | quantum dots A rtificial photosynthesis (AP) represents an important strategy for energy conversion from sunlight to storage in chemical bonds (1-4). Unlike natural photosynthesis in which CO 2 + H 2 O are converted into carbohydrates and O 2 , the key energy-storing reaction in AP is the splitting of water into its constituent elements of hydrogen and oxygen (5-16). As a redox reaction, water splitting can be divided into two half-reactions, of which the light-driven generation of H 2 is the reductive component. Many systems for the photogeneration of H 2 have been described over the years and they typically consist of a light absorber, a catalyst for H 2 formation, and sources of protons and electrons. For systems that function in aqueous media, the protons are provided by water, whereas for nonaqueous systems, the protons are provided by weak, generally organic acids. The source of electrons in these photochemical systems is generally a sacrificial electron donor-that is, a compound that decomposes following one electron oxidation.Reports of the light-driven generation of hydrogen date back more than 30 y, beginning with a multicomponent system containing [Ru(bpy) 3 ] 2+ (where bpy is 2,2′-bipyridine) as the chromophore or photosensitizer (PS) and colloidal Pt as the catalyst for making H 2 from protons and electrons (17). In these and many subsequent systems, electron mediators were used to accept an electron from the excited chromophore, PS*-thereby serving as an oxidative quencher-and transfer it to the catalyst. Whereas two of the initial mediators were bpy complexes of rhodium and cobalt (17, 18), the overwhelming majority of electron mediators in these systems were dialkylated 2,2′-and 4,4′-bipyridines and their derivatives (19)(20)(21)(22). The most extensively used of these mediators was methyl viologen (MV 2+ , dimethyl-4,4′-bipyridinium, usually as its chloride salt). These mediators were subsequently found to undergo deactivation in their role by hydrogenation (23, 24). The sacrificial electron donors used in these studies depended on system pH and were generally based on compounds having tertiary amine func...

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mentioning

confidence: 99%

Photogeneration of hydrogen from water using CdSe nanocrystals demonstrating the importance of surface exchange

Das

Han

Haghighi

et al. 2013

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

129

139

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“…In 1983, Lehn and co-workers reported the first photocatalytic H 2 evolution system using a cobaloxime-based catalyst as the catalyst [7]. The use of a BF 2 -annulated cobaloxime for the photocatalytic generation of H 2 has also been reported by Artero and…”

Section: Introductionmentioning

confidence: 94%

“…Catalysts made of earth-abundant cobalt element have been reported to exhibit efficient catalytic activities for the H 2 evolution from water splitting [7][8][9][10][11]. In 1983, Lehn and co-workers reported the first photocatalytic H 2 evolution system using a cobaloxime-based catalyst as the catalyst [7].…”

Section: Introductionmentioning

confidence: 99%

A cobalt-based polyoxometalate catalyst for efficient visible-light-driven H2 evolution from water splitting

Teng

et al. 2015

Catalysis Communications

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“…Other functional hydrogenase mimics may incorporate metals such as Fe and Ni used for proton reduction by nature, but not resemble enzyme active sites otherwise (figure 2b,c) [26]. On the other hand, catalysts incorporating inexpensive metals that are not found in natural hydrogenases such as cobalt [28,[35][36][37][38] (figure 2d,e) and molybdenum [39] have been successful. Though many metal complexes are able to reduce protons to hydrogen, most of these catalysts have limitations.…”

Section: Molecular Components For Solar Hydrogen Generationmentioning

confidence: 99%

“…Molecular photochemical systems for hydrogen evolution may be assembled into a structurally defined system via [28]. (e) Robust cobalt pentapyridine catalyst that functions in water at neutral pH [29].…”

Section: Molecular Components For Solar Hydrogen Generationmentioning

confidence: 99%

Multidisciplinary approaches to solar hydrogen

Bren

2015

Interface Focus.

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This review summarizes three different approaches to engineering systems for the solar-driven evolution of hydrogen fuel from water: molecular, nanomaterials and biomolecular. Molecular systems have the advantage of being highly amenable to modification and detailed study and have provided great insight into photophysics, electron transfer and catalytic mechanism. However, they tend to display poor stability. Systems based on nanomaterials are more robust but also are more difficult to synthesize in a controlled manner and to modify and study in detail. Biomolecular systems share many properties with molecular systems and have the advantage of displaying inherently high efficiencies for light absorption, electron–hole separation and catalysis. However, biological systems must be engineered to couple modules that capture and convert solar photons to modules that produce hydrogen fuel. Furthermore, biological systems are prone to degradation when employed in vitro . Advances that use combinations of these three tactics also are described. Multidisciplinary approaches to this problem allow scientists to take advantage of the best features of biological, molecular and nanomaterials systems provided that the components can be coupled for efficient function.

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ChemInform Abstract: EFFICIENT HOMOGENEOUS PHOTOCHEMICAL HYDROGEN GENERATION AND WATER REDUCTION MEDIATED BY COBALOXIME OR MACROCYCLIC COBALT COMPLEXES

Cited by 36 publications

References 0 publications

Photogeneration of hydrogen from water using CdSe nanocrystals demonstrating the importance of surface exchange

Photogeneration of hydrogen from water using CdSe nanocrystals demonstrating the importance of surface exchange

A cobalt-based polyoxometalate catalyst for efficient visible-light-driven H2 evolution from water splitting

Multidisciplinary approaches to solar hydrogen

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