Characterization and functional assessment of a cobalt(III)-oxo cubane cluster water oxidation catalyst immobilized on ITO

Yuan, Hao; Newton, De'Andra; Seymour, Luke; Metz, Anja; Holder, Alvin A.; Ofoli, Robert Y.

doi:10.1016/j.catcom.2014.06.007

Cited by 12 publications

(8 citation statements)

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“…Our research group and collaborators have been interested in the development of transition metal complexes that contain cobalt metal centres [24][25][26][27][28][29][30][31], as well as inorganic reaction mechanisms that involve electron transfer processes [25,26,[32][33][34][35][36]. In a recent report, we outlined the preparation and application a novel mixed-metal binuclear ruthenium(II)-cobalt(II) photocatalysts ([Ru(pbt) 2 (Lpyr)Co(dmgBF 2 ) 2 (H 2 O)](PF 6 ) 2 (where pbt = 2-(2′-pyridyl)benzothiazole, L-pyr = (4pyridine)oxazolo [4,5-f]phenanthroline, and dmgBF 2 = difluoroboryldimethylglyoximato) for photocatalytic production of hydrogen [24].…”

Section: Introductionmentioning

confidence: 99%

Assessing the stability of the Co(I) species of two mononuclear dichlorocobalt compounds bearing 2,2′-bipyridine and trans-2-(2′-quiolyl)methylene-3-quinuclidione via 59Co NMR spectroscopy, electrochemical, and catalyzed proton electroreduction studies

Lawrence

Holder

2016

Inorganica Chimica Acta

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The Co(I) species resulting from the reduction of two mononuclear species [CoL n Cl 2 ] (where L = 2,2'bipyridine (bpy) and n = 2, or L = trans-2-(2'-quiolyl)methylene-3-quinuclidione (quin) and n = 1), was studied by 59 Co NMR spectroscopy, UV-visible-NIR spectroscopy, and spectroelectrochemical techniques. A quasi-stable Co(I) species produced by the reduction of [Co(bpy) 2 Cl 2 ] was studied and gave a 59 Co NMR spectroscopic chemical shift of 2934 ppm in CD 3 CN-D 2 O (4:1, v/v) and a broad peak of  max = 600 nm in the UV-visible region of the spectrum. The Co(I) species generated from [Co(quin)Cl 2) (when reduced by electrochemical methods) was found to be unstable and produced a transient of  max = 530 nm. Both [CoL n Cl 2 ] species were examined as electrocatalysts for the proton reduction in an acetonitrile-water solvent mixture in the presence of p-cyanoanilinium tetrafluoroborate. The electrochemical properties of both species showed a dependence on the supporting electrolyte which also affected the electrocatalytic behavior. The simulation of the cyclic voltammograms in CH 3 CN-H 2 O (4:1, v/v) allowed for the extraction of kinetic data and suggested a homogenous reaction following the reduction to a Co(I) metal centre with rate constants k = 0.01 s-1 and 2 M s-1 for the Co(I) species with the ligands, bpy and quin, respectively. Analysis of the head space of controlled potential electrolysis experiments for an hour, in the presence of p-cyanoanilinium tetrafluoroborate, confirmed the production of hydrogen, and also showed that the supporting electrolyte affected the production of hydrogen at a glassy carbon electrode in CH 3 CN-H 2 O (either 1:1 or 4:1, v/v). A mechanism was postulated which involved a Co III-H species as the most likely candidate and appeared to involve both a homolytic and a heterolytic pathway towards the production of hydrogen.

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Section: Introductionmentioning

confidence: 99%

Assessing the stability of the Co(I) species of two mononuclear dichlorocobalt compounds bearing 2,2′-bipyridine and trans-2-(2′-quiolyl)methylene-3-quinuclidione via 59Co NMR spectroscopy, electrochemical, and catalyzed proton electroreduction studies

Lawrence

Holder

2016

Inorganica Chimica Acta

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“…This cobalt‐based catalyst, used to generate an “artificial leaf”, is easy to synthesize in situ and has excellent catalytic performance . Our group has similarly demonstrated that a cobalt‐based catalyst synthesized ex situ and deposited on a conductive surface retains its activity toward water oxidation . Although work on cobalt‐based water oxidation catalysts continues, manganese‐based WOCs have recently become the focus of much research, because of several tunable and unique attributes.…”

Section: Figurementioning

confidence: 97%

Synthesis of MnO_x Water Oxidation Catalyst on Fluorine‐Doped Tin Oxide with a Dual‐Series Cyclic Voltammetry Method

et al. 2016

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This Communication reports an ew methodf or synthesizing manganese-basedw ater oxidation catalysts in situ in aqueous media. The method provides powerful tunability of the electrodeposition process to enable independentc ontrol over the morphology of the catalytic film and the oxidation state of the catalyst. Our results show that the first cyclic voltammetry (CV) series produces af ilm with an anoscale fibrous structure, whereas the second CV series improves its catalytic performance by enhancing the oxidation state of the film without damaging the existing surfacem orphology.S canning electron microscopy and transmission electron microscopyw ere used to characterize the morphologyo ft he MnO x film, CV was used to assess the catalyst functionality,a nd long-term amperometry was used to assess the stability.The use of artificial photosynthesis to produce hydrogen fuel has long been regarded as one of the most promising and sustainable solutions to the worldwide energy demand.[1] The process involves two main half-reactions:w ater oxidation to release hydrogeni ons and oxygen, and hydrogen-ion reconstitution to produce hydrogen fuel.[2] The water oxidation reaction is the rate-limiting step in this process, because its large overpotentiali sasignificant energy barrier. [3] In the past, Ru-and Ir-based catalysts have been used for this reaction, but the cost of these rare earth elements greatly limit their use on al arge scale.[4] Within the past decade, different water oxidation catalysts( WOCs) based on inexpensive and abundant materials have been developed to replace the precious metal oxides, including the successful "Co-Pi" catalyst of Kanan and Nocera.[5] This cobalt-based catalyst, used to generate an "artificial leaf", is easy to synthesize in situ and has excellent catalytic performance.[6] Our group has similarly demonstrated that ac obalt-based catalysts ynthesized ex situ and deposited on ac onductive surface retains its activity toward water oxidation.[7] Although work on cobalt-based water oxidation catalysts continues, manganese-based WOCs have recently become the focus of much research, because of severalt unable and unique attributes. Manganese is not ar are earth element, and its complexes are largely nontoxic.[8] Equally important, manganese is the primary elementi nt he natural oxygen evolvingc enter (OEC) of plants and, in general, manganesebased WOCs have highere fficiencies and longere ffective lifetimes. [9] Various methods have been reported for synthesizing manganese-based water splitting complexes, both ex situ [10] and in situ.[11] Among these, electrodeposition has the benefito f simplicity in experimental setup along with easily controllable deposition conditions. Typically,e lectrodeposition has been performedb yu sing chronoamperometry [12] or as ingle series of cyclic voltammetry (CV). [13] In this work, we explored the use of multiple CV series for the electrodeposition of aM nO x catalyst on fluorine-doped tin oxide (FTO) with the aim to produce ac atalytic film with ah ig...

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“…Ofoli and co-workers recently immobilized Co cubane 96 on ITO and showed that the cubane catalyst retained its catalytic activity similarly to the homogeneous catalytic entity. 262 Sun and co-workers have also coupled Co cubane 96 to [Ru(bpy) 3 ] 2+ -type photosensitizers to generate two supramolecular assemblies, assembly 104 depicted in Fig. 39 and the cyclic assembly 105 consisting of two Co cubane and two [Ru(bpy) 3 ] 2+ units (not shown).…”

Section: Co Cubanes As Mimics Of the Catalytic Core In The Oxygen-evomentioning

confidence: 99%

Water oxidation using earth-abundant transition metal catalysts: opportunities and challenges

2016

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Catalysts for the oxidation of H2O are an integral component of solar energy to fuel conversion technologies. Although catalysts based on scarce and precious metals have been recognized as efficient catalysts for H2O oxidation, catalysts composed of inexpensive and earth-abundant element(s) are essential for realizing economically viable energy conversion technologies. This Perspective summarizes recent advances in the field of designing homogeneous water oxidation catalysts (WOCs) based on Mn, Fe, Co and Cu. It reviews the state of the art catalysts, provides insight into their catalytic mechanisms and discusses future challenges in designing bioinspired catalysts based on earth-abundant metals for the oxidation of H2O.

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Characterization and functional assessment of a cobalt(III)-oxo cubane cluster water oxidation catalyst immobilized on ITO

Cited by 12 publications

References 9 publications

Assessing the stability of the Co(I) species of two mononuclear dichlorocobalt compounds bearing 2,2′-bipyridine and trans-2-(2′-quiolyl)methylene-3-quinuclidione via 59Co NMR spectroscopy, electrochemical, and catalyzed proton electroreduction studies

Assessing the stability of the Co(I) species of two mononuclear dichlorocobalt compounds bearing 2,2′-bipyridine and trans-2-(2′-quiolyl)methylene-3-quinuclidione via 59Co NMR spectroscopy, electrochemical, and catalyzed proton electroreduction studies

Synthesis of MnO_x Water Oxidation Catalyst on Fluorine‐Doped Tin Oxide with a Dual‐Series Cyclic Voltammetry Method

Water oxidation using earth-abundant transition metal catalysts: opportunities and challenges

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Characterization and functional assessment of a cobalt(III)-oxo cubane cluster water oxidation catalyst immobilized on ITO

Cited by 12 publications

References 9 publications

Assessing the stability of the Co(I) species of two mononuclear dichlorocobalt compounds bearing 2,2′-bipyridine and trans-2-(2′-quiolyl)methylene-3-quinuclidione via 59Co NMR spectroscopy, electrochemical, and catalyzed proton electroreduction studies

Assessing the stability of the Co(I) species of two mononuclear dichlorocobalt compounds bearing 2,2′-bipyridine and trans-2-(2′-quiolyl)methylene-3-quinuclidione via 59Co NMR spectroscopy, electrochemical, and catalyzed proton electroreduction studies

Synthesis of MnOx Water Oxidation Catalyst on Fluorine‐Doped Tin Oxide with a Dual‐Series Cyclic Voltammetry Method

Water oxidation using earth-abundant transition metal catalysts: opportunities and challenges

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Synthesis of MnO_x Water Oxidation Catalyst on Fluorine‐Doped Tin Oxide with a Dual‐Series Cyclic Voltammetry Method