Polyoxometalate water oxidation catalysts and the production of green fuel

Lv, Hongjin; Geletii, Yurii V.; Zhao, Chuanzhen; Vickers, James W.; Zhu, Guibo; Luo, Zhen; Song, Jié; Lian, Tianquan; Musaev, Djamaladdin G.; Hill, Craig L.

doi:10.1039/c2cs35292c

Cited by 717 publications

(400 citation statements)

References 303 publications

(278 reference statements)

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“…into the vacant sites has been used to synthesize several metal-substituted POMs with controlled multinuclear active sites in both aqueous and organic media [7,11,23]. These molecular catalysts exhibit significant activity and selectivity for a wide range of reactions [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] [92][93][94].…”

Section: Transition-metal-substituted Polyoxometalatesmentioning

confidence: 99%

Base Catalysis by Mono- and Polyoxometalates

Kamata

Sugahara

2017

Catalysts

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Abstract:In sharp contrast with acid-, photo-, and oxidation-catalysis by polyoxometalates, base catalysis by polyoxometalates has scarcely been investigated. The use of polyoxometalates as base catalysts have very recently received much attention and has been extensively investigated. Numerous mono-and polyoxometalate base catalyst systems effective for the chemical fixation of CO 2 , cyanosilylation of carbonyl compounds, and C-C bond forming reactions have been developed. Mono-and polyoxometalate base catalysts are classified into four main groups with respect to their structures: (a) monomeric metalates; (b) isopolyoxometalates; (c) heteropolyoxometalates; and (d) transition-metal-substituted polyoxometalates. This review article focuses on the relationship among the molecular structures, the basic properties, and the unique base catalysis of polyoxometalates on the basis of groups (a)-(d). In addition, reaction mechanisms including the specific activation of substrates and/or reagents such as the abstraction of protons, nucleophilic action toward substrates, and bifunctional action in combination with metal catalysts are comprehensively summarized.

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Section: Transition-metal-substituted Polyoxometalatesmentioning

confidence: 99%

Base Catalysis by Mono- and Polyoxometalates

Kamata

Sugahara

2017

Catalysts

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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.

142

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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“…[4][5][6] One the POMs' important properties is their superior catalytic performance in numerous processes which has been exploited in industrial processes. [7][8][9][10][11][12][13] However, the industrial application of POMbased homogeneous catalytic systems has been largely restricted by the poor solubility of POMs in common organic solvents due to their crystalline nature, high negative charge, low energy lattice [14] , contamination/separation and decomposition issues. Consequently, design of POM-based heterogeneous catalysts is a potentially alternative way to overcome the above limitations and fine control of the POMbased material's functionality.…”

Section: Introductionmentioning

confidence: 99%

Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions

Jia

Fang

Zhang

et al. 2015

Chemistry A European J

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Abstract:The family of polyoxometalate (POM) intercalated layered double hydroxides (LDHs) composite materials has shown great promise for the design of functional materials with numerous applications. It is known that intercalation of the classical Keggin polyoxometalate (POM) of [PW12O40] 3-(PW12) into layered double hydroxides (LDHs) is very unlikely to take place by conventional ion exchange methods due to spatial and geometrical restrictions. In this paper, such intercalated compound of Mg0.73Al0.22(OH)2 [PW12O40]0.04·0.98H2O (Mg3Al-PW12) has been successfully obtained by adopting a spontaneous flocculation method. The Mg3Al-PW12 has been fully characterized using a wide range of methods (XRD, SEM, TEM, XPS, EDX, XPS, FT-IR, NMR, BET). XRD patterns of Mg3Al-PW12 exhibit no impurity phase usually observed next to the (003) diffraction peak. Subsequent application of the Mg3Al-PW12 as catalyst in Knoevenagel condensation reactions of various aldehydes and ketones with Z-CH2-Z' type substrates (ethylcyanoacetate and malononitrile) at 60 o C in mixed solvents (Vipropanol:Vwater = 2 : 1) demonstrated highly efficient catalytic activity. The synergistic effect between the acidic and basic sites of the Mg3Al-PW12 composite proved to be crucial for the efficiency of the condensation reactions. Additionally, the Mg3Al-PW12 catalysed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate demonstrated the highest turnover number (TON) of 47980 reported so far.

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Polyoxometalate water oxidation catalysts and the production of green fuel

Cited by 717 publications

References 303 publications

Base Catalysis by Mono- and Polyoxometalates

Base Catalysis by Mono- and Polyoxometalates

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

Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions

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Polyoxometalate water oxidation catalysts and the production of green fuel

Cited by 717 publications

References 303 publications

Base Catalysis by Mono- and Polyoxometalates

Base Catalysis by Mono- and Polyoxometalates

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

Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions

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