Isolated Seven-Coordinate Ru(IV) Dimer Complex with [HOHOH]<sup>−</sup> Bridging Ligand as an Intermediate for Catalytic Water Oxidation

Duan, Lele; Fischer, Andreas; Xu, Yongqian; Sun, Licheng

doi:10.1021/ja9034686

Cited by 478 publications

(520 citation statements)

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“…This is highlighted in the work of Suntivich 303 and Subbaraman 304 outlined above and concurrently through the dramatic rise in interest in the area of homogeneous water oxidation catalysis. Notable works include those of Meyer, [305][306][307][308] Thummel, [309][310][311] Llobet, [312][313][314][315][316] Sun, [316][317][318][319] and Crabtree [320][321][322] to name but a few. One of the advantages of these systems is the ease with which mechanistic studies can be performed.…”

Section: Mechanistic Studies Of the Oermentioning

confidence: 99%

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Doyle

Godwin

Brandon

et al. 2013

Phys. Chem. Chem. Phys.

537

565

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This paper presents a review of the redox and electrocatalytic properties of transition metal oxide electrodes, paying particular attention to the oxygen evolution reaction. Metal oxide materials may be prepared using a variety of methods, resulting in a diverse range of redox and electrocatalytic properties. Here we describe the most common synthetic routes and the important factors relevant to their preparation. The redox and electrocatalytic properties of the resulting oxide layers are ascribed to the presence of extended networks of hydrated surface bound oxymetal complexes termed surfaquo groups. This interpretation presents a possible unifying concept in water oxidation catalysis -bridging the fields of heterogeneous electrocatalysis and homogeneous molecular catalysis. In contextOver the past 50 years considerable research efforts have been devoted to the realisation of efficient, economical and renewable energy sources. Metal oxide materials have played a large part in this drive with demonstrated applications at both the research and commercial level. Their use in areas such as batteries, fuel cells and water electrolysis has resulted in the development of materials with a diverse range of structural and chemical properties. In all cases, understanding the fundamental electrochemistry of the material can be invaluable for rational design and optimisation. This review focuses on the redox, charge transport and electrocatalytic properties of transition metal oxide electrodes as they pertain to the electrolytic splitting of water. Particular emphasis is placed on the nature of the active surface which is interpreted in terms of hydrated interlinked oxymetal complexes termed surfaquo groups. In this way, the review seeks to bridge the gap between heterogeneous electrocatalysis and homogeneous molecular catalysis for water oxidation, areas of considerable modern interest and activity.

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Section: Mechanistic Studies Of the Oermentioning

confidence: 99%

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Doyle

Godwin

Brandon

et al. 2013

Phys. Chem. Chem. Phys.

537

565

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“…1) with OPRs up to 300 s −1 (19, 20); a seven-coordinate dimeric Ru IV intermediate (D7Ru IV ) (Fig. 1) is involved in the O─O bond formation step (20,21).A general problem encountered in molecular WOCs is the decomposition of catalysts. Ligand dissociation and oxidative decomposition have been considered as the major deactivation pathways.…”

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confidence: 99%

“…As mentioned above, the main deactivation pathway of the Ru-bda catalysts is the axial ligand dissociation. For the water oxidation reaction catalyzed by the Ru-bda catalysts, the rate limiting step is the coupling step of 2Ru V ═O → Ru IV ─O─O─Ru IV , and thus Ru V is the dominant species at the catalytic steady state (19,20). We thereby identified the ligand-exchange reaction at the Ru V state, in which one of the ligands (L) is replaced by OH 2 (Scheme 1).…”

mentioning

confidence: 99%

“…Very recently, we reported a family of highly active Ru-based WOCs ½RuðbdaÞL 2 (H 2 L ¼ 2;2 -bipyridine-6,6′-dicarboxylic acid; L ¼ 4-picoline, A; L ¼ isoquinoline, B) ( Fig. 1) with OPRs up to 300 s −1 (19,20); a seven-coordinate dimeric Ru IV intermediate (D7Ru IV ) ( Fig. 1) is involved in the O─O bond formation step (20,21).…”

mentioning

confidence: 99%

“…1) with OPRs up to 300 s −1 (19,20); a seven-coordinate dimeric Ru IV intermediate (D7Ru IV ) ( Fig. 1) is involved in the O─O bond formation step (20,21).…”

mentioning

confidence: 99%

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Highly efficient and robust molecular ruthenium catalysts for water oxidation

Duan

Araújo

Ahlquist

et al. 2012

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

Self Cite

216

199

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Water oxidation catalysts are essential components of light-driven water splitting systems, which could convert water to H 2 driven by solar radiation (H 2 O þ hν → 1∕2O 2 þ H 2 ). The oxidation of water (H 2 O → 1∕2O 2 þ 2H þ þ 2e − ) provides protons and electrons for the production of dihydrogen (2H þ þ 2e − → H 2 ), a clean-burning and high-capacity energy carrier. One of the obstacles now is the lack of effective and robust water oxidation catalysts. Aiming at developing robust molecular Ru-bda (H 2 bda ¼ 2,2 0 -bipyridine-6,6′-dicarboxylic acid) water oxidation catalysts, we carried out density functional theory studies, correlated the robustness of catalysts against hydration with the highest occupied molecular orbital levels of a set of ligands, and successfully directed the synthesis of robust Ru-bda water oxidation catalysts. A series of mononuclear ruthenium complexes ½RuðbdaÞL 2 (L ¼ pyridazine, pyrimidine, and phthalazine) were subsequently synthesized and shown to effectively catalyze Ce IV -driven ½Ce IV ¼ CeðNH 4 Þ 2 ðNO 3 Þ 6 water oxidation with high oxygen production rates up to 286 s −1 and high turnover numbers up to 55,400.catalysis | density function theory | seven coordination | photosystem II | solar fuels I n pursuit of sustainable energy systems such as solar fuels, much effort has been spent on water splitting to hydrogen and oxygen since hydrogen is a potential clean energy carrier and water is an abundant and environmentally benign resource (1-5). Water splitting consists of two half reactions: (i) water oxidationIn practice, an overpotential is always present, leading to an even higher applied potential. The former half reaction requires strongly oxidizing conditions and is generally considered as the bottleneck of the whole water-splitting process due to the multiple protonelectron transfers and the formation of the O─O bond. Over the last few years, there has been an increasing development of water oxidation catalysts (WOCs) and many transition metal-based catalysts, including Ru (4, 5), Ir (6-8), Co (9-13), Fe (14,15), and Mn (16-18), have been reported with oxygen production rates (OPRs: mole oxygen produced per mole catalyst per second) ≤5 s −1 . Very recently, we reported a family of highly active Ru-based WOCs ½RuðbdaÞL 2 (H 2 L ¼ 2;2 -bipyridine-6,6′-dicarboxylic acid; L ¼ 4-picoline, A; L ¼ isoquinoline, B) ( Fig. 1) with OPRs up to 300 s −1 (19, 20); a seven-coordinate dimeric Ru IV intermediate (D7Ru IV ) (Fig. 1) is involved in the O─O bond formation step (20,21).A general problem encountered in molecular WOCs is the decomposition of catalysts. Ligand dissociation and oxidative decomposition have been considered as the major deactivation pathways. The groups of Llobet, Meyer, and Sun have demonstrated an improved durability of their catalysts by immobilizing catalysts on the electrode/material surface and thereby dramatically suppressing the intermolecular oxidative decomposition pathway (22-25).For our Ru-bda catalysts, the main deactivation pathway has been found to b...

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Oxygen Production from Water: Molecular Catalysts

Llobet

Romain

2005

Encyclopedia of Inorganic Chemistry

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This article presents an overview of the established basis needed for the oxidation of water to dioxygen, and thus the demands a catalyst needs to fulfill to be able to perform this reaction. It further describes the structure, redox properties, and performance of selected molecular catalysts that have been reported to be able to perform this difficult reaction and that can be considered as references in the field. The scarce reaction mechanism studies that have been described are also summarized and discussed. The article mainly deals with Ru complexes, because they constitute most of the available literature at the moment, and are classified as a function of their nuclearity. Other transition metal complexes of relevance based on Ir, Co, and Mn are also described. Finally, a few conclusions are drawn from the global description of all of the catalysts presented here, and the challenges and opportunities in the field are also discussed.

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Isolated Seven-Coordinate Ru(IV) Dimer Complex with [HOHOH]⁻ Bridging Ligand as an Intermediate for Catalytic Water Oxidation

Cited by 478 publications

References 32 publications

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Highly efficient and robust molecular ruthenium catalysts for water oxidation

Oxygen Production from Water: Molecular Catalysts

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Isolated Seven-Coordinate Ru(IV) Dimer Complex with [HOHOH]− Bridging Ligand as an Intermediate for Catalytic Water Oxidation

Cited by 478 publications

References 32 publications

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Highly efficient and robust molecular ruthenium catalysts for water oxidation

Oxygen Production from Water: Molecular Catalysts

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Isolated Seven-Coordinate Ru(IV) Dimer Complex with [HOHOH]⁻ Bridging Ligand as an Intermediate for Catalytic Water Oxidation