Formation of a metal-hydride bond and the insertion of carbon dioxide. Key steps in the electrocatalytic reduction of carbon dioxide to formate anion

Pugh, John R.; Bruce, Mitchell R. M.; Sullivan, B. Patrick; Meyer, Thomas J.

doi:10.1021/ic00001a016

Cited by 185 publications

(64 citation statements)

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“…For comparison, at Ϫ1.5 V, Ϸ50% of the potential is dissipated as heat. Preliminary attempts to use a ruthenium catalyst to reduce CO 2 to formate electrochemically required similarly high overpotentials and also led to a mixture of products (29). Formate dehydrogenase from Pseudomonas oxalaticus was applied also to the electrochemical reduction of CO 2 (25).…”

Section: Discussionmentioning

confidence: 99%

Reversible interconversion of carbon dioxide and formate by an electroactive enzyme

Reda

Plugge

Abram

et al. 2008

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

496

420

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Carbon dioxide (CO2) is a kinetically and thermodynamically stable molecule. It is easily formed by the oxidation of organic molecules, during combustion or respiration, but is difficult to reduce. The production of reduced carbon compounds from CO 2 is an attractive proposition, because carbon-neutral energy sources could be used to generate fuel resources and sequester CO 2 from the atmosphere. However, available methods for the electrochemical reduction of CO2 require excessive overpotentials (are energetically wasteful) and produce mixtures of products. Here, we show that a tungsten-containing formate dehydrogenase enzyme (FDH1) adsorbed to an electrode surface catalyzes the efficient electrochemical reduction of CO 2 to formate. Electrocatalysis by FDH1 is thermodynamically reversible-only small overpotentials are required, and the point of zero net catalytic current defines the reduction potential. It occurs under thoroughly mild conditions, and formate is the only product. Both as a homogeneous catalyst and on the electrode, FDH1 catalyzes CO 2 reduction with a rate more than two orders of magnitude faster than that of any known catalyst for the same reaction. Formate oxidation is more than five times faster than CO 2 reduction. Thermodynamically, formate and hydrogen are oxidized at similar potentials, so formate is a viable energy source in its own right as well as an industrially important feedstock and a stable intermediate in the conversion of CO2 to methanol and methane. FDH1 demonstrates the feasibility of interconverting CO2 and formate electrochemically, and it is a template for the development of robust synthetic catalysts suitable for practical applications.electrocatalysis ͉ formate dehydrogenase ͉ formate oxidation ͉ protein film voltammetry ͉ carbon dioxide reduction C arbon dioxide (CO 2 ) is a kinetically and thermodynamically stable molecule that is difficult to chemically activate. As the unreactive product of the combustion of carbon-containing molecules, such as fossil fuels, and biological respiration, it is accumulating in the atmosphere and is a major cause of concern in climate-change scenarios (1, 2). Consequently, catalysts that are able to sequester CO 2 from the atmosphere rapidly and efficiently, to generate reduced carbon compounds for use as fuels or chemical feedstocks, have long been sought after. Organometallic complexes that insert CO 2 into an M-H bond and the use of supercritical CO 2 to facilitate its hydrogenation are two promising approaches to the development of a homogeneous catalytic process (3-5). Extensive efforts to develop electrode materials for the direct, electrochemical reduction of CO 2 have been made also, but so far, they require the application of extreme potentials (are inefficient energetically) or they are nonspecific and produce mixtures of products (4, 6, 7). An efficient and specific method for reducing CO 2 electrochemically has obvious applications in a future energy economy based on the cyclic reduction and oxidation of simple carbon compound...

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Section: Discussionmentioning

confidence: 99%

Reversible interconversion of carbon dioxide and formate by an electroactive enzyme

Reda

Plugge

Abram

et al. 2008

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

496

420

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“…Progress has also been made on catalytic reduction of CO 2 to CO (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36). Both present a formidable challenge in chemical reactivity.…”

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confidence: 99%

Splitting CO ₂ into CO and O ₂ by a single catalyst

Chen

Concepcion

Brennaman

et al. 2012

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

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180

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The metal complex ½ðtpyÞðMebim-pyÞRu II ðSÞ 2þ (tpy ¼ 2,2 0 : 6 0 ,2 0 0 -terpyridine; Mebim-py ¼ 3-methyl-1-pyridylbenzimidazol-2-ylidene; S ¼ solvent) is a robust, reactive electrocatalyst toward both water oxidation to oxygen and carbon dioxide reduction to carbon monoxide. Here we describe its use as a single electrocatalyst for CO 2 splitting, CO 2 → CO þ 1∕2 O 2 , in a two-compartment electrochemical cell.artificial photosynthesis | polypyridyl Ru complexes | proton coupled electron transfer | single-site catalysis | solar fuels R ising energy prices, diminishing reserves of petroleum, and environmental concerns are driving new thinking about our energy future. Given its availability, with approximately 10,000 times the daily energy input required to meet current energy consumption, solar energy could be the ultimate answer. However, solar energy is diffuse, spread over the earth's surface, and requires vast collection areas for large-scale applications (1). A more difficult challenge is the intermittency of the sun as an energy source. Meeting the challenge of providing power at night will require energy storage on massive scales at levels exceeding the ability of existing or foreseeable energy storage technologies (2, 3). The only realistic alternative is energy storage in chemical bonds and the increasingly popular concept of "solar fuels." Solar fuels mimic natural photosynthesis in using solar energy and artificial photosynthesis to convert readily available sources, water and carbon dioxide, into highenergy fuels. Target reactions include water splitting into hydrogen and oxygen and reduction of carbon dioxide to carbon monoxide, other oxygenates, or hydrocarbons (Eqs. 1-3), as follows:Carrying out these reactions presents a major challenge in chemical reactivity given their multiphoton, multielectron, multiatom character. It is reassuring that similar hurdles have been overcome in natural photosynthesis, in which light-driven reduction of CO 2 to carbohydrates by water occurs (Eq. 4). However, photosynthesis in green plants took 2-3 billion years to evolve and utilizes a complex architecture that utilizes thousands and thousands of atoms and multiple integrated assemblies (4, 5).A simplifying factor, suggesting a mechanistic approach, comes with recognition that the target energy storage reactions can be split into constituent "half reactions" which are shown for CO 2 splitting in Eqs. 5 and 6. Photosynthesis in green plants occurs in the thylakoid membrane and uses physically separated molecular assemblies for light-driven water oxidation (Photosystem II) and CO 2 reduction (Photosystem I and the Calvin cycle) (6, 7). Electron/proton equilibration occurs by intra-or transmembrane electron/proton transfer channels driven by free energy gradients.Application of a "half-reaction" strategy in artificial photosynthesis poses similar challenges. In both water oxidation and CO 2 reduction, mechanisms involving one-electron reactions are energetically untenable. They result in • OH on oxidation or CO 2•− o...

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“…In light of previous reports, [10,14,36,37] experimental observations and standard electron counting rules lead us to propose a photocatalytic mechanismf or HCO 2 Hp roduction from CO 2 by using complexes 1 + + Cl À and 2 + + Cl À (Scheme 2a nd FigureS8). [36,37] In addition, the fact that we did not observe formation of CO as ap roduct also mitigated against formation of aC O 2 adduct with Ru 0 .T hus, protonation of this lone electron pair of Ru 0 yields the hydridec omplex, RuH.T he insertiono fC O 2 into the RuÀHc omplex yields the metallacarboxylic acid species RuCOOH,w hich through reduction releases formate and generatest he Ru I complex Ru + + .T he catalytic cycle closes with return to Ru 0 by reduction from PS À . Entry into the catalytic cycle comes from the reduction of A ( Figure S10), which during optimization, spontaneously dissociated aC l À anion to yield ad istorted square pyramidal complex labeled Ru 0 .V isualization of the HOMO of this complex shows that the electron density is localized in ad z 2 -type orbital with some contributions from the CO ligands ( Figures S11a nd S12).…”

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confidence: 70%

Visible‐Light Photocatalytic Reduction of CO₂ to Formic Acid with a Ru Catalyst Supported by N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine Ligands

et al. 2019

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Visible-light photocatalytic CO 2 reduction is carried out by using aR u II complex supportedb yN,N'-bis(diphenylphosphino)-2,6-diaminopyridine( "PNP")l igands, an unprecedented molecular architecture for this reaction that breaks the longstanding domination of a-diimine ligands. These competent catalysts transform CO 2 into formic acid with high selectivity and turnover number.Aproposed mechanism, with combined electron transfer and catalytic cycles, models the experimental rate of formic acid production.Designing and assembling catalysts that can utilize the energy of visible light to overcome the barriers to reduce CO 2 is an important fundamentala nd technological challenge. Success in this endeavor requires confronting the inherent stabilitya nd low thermodynamic value of CO 2 and would transform this ubiquitous waste product into av aluable feedstock. For example, photocatalytic formation of formic acid, at wo-electron reductionp roduct of CO 2 ,w ould yield ac ommodity chemical and al iquid fuel. Furthermore, formic acid has been identified and explored as ap otential carrier of dihydrogen. [1,2] Homogeneous catalysts have been developed for CO 2 reduction under both electrochemical and photochemical conditions. [3][4][5][6] Photocatalysis is ap articularly appealing approacha s it relies on an essentially limitless and clean solar energy source.P hotocatalytic systemsc onsisto fi ntegrated components that include ap hotosensitizer (PS)f or harvesting the energy of the light, an electron donor (ED)t hat provides electrons for the reduction, and ac atalyst (CAT)t hat is as ite for the transformation of CO 2 .T oo ur knowledge,s ince their discovery in 1985, [7] all of the reported molecular photocatalysts based on Ru II have used a-diimine supporting ligandsa nd these speciesh ave fallen into two broad groups.O ne class are bis(a-diimine) speciesr epresentedb ycis-[Ru(N^N) 2 (CO) 2 ] 2 + [8][9][10][11] and the other are mono(a-diimine) catalysts represented by cis,trans-[Ru(N^N)(CO) 2 Cl 2 ]. [12][13][14] Althoughavariety of substituents on the a-diimine ligands have been productively explored to improvec atalystp erformance, given the maturity of this field, ab roader variationo fm olecular architecture is required to provide new insights and stimulate new concepts in this field. Ligand variation and discoverya re ac entral challenge in catalysis and expanding Ru-based photocatalysts beyond the restrictions of a-diimine support is certainly warranted. Support for this approachc omes from av ery recent report on the use of ap hotocatalytic phosphine-substituted Ru II terpyridine complex-trans-[Ru(tpy)(8-quinolyl(diphenyl)phosphine)-(MeCN)] 2 + -that functions as both ap hotosensitizer andacatalyst for CO 2 reduction. [15,16] Recently,p incer ligand-supported catalysts of Fe, Co, Ru, and Ir have been shown to have excellent activity and selectivity for hydrogenation of CO 2 . [17][18][19][20][21][22][23] Pincer-supported ruthenium complexes can catalyze hydrogenation of CO 2 to yield formate, as wella st he ...

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Formation of a metal-hydride bond and the insertion of carbon dioxide. Key steps in the electrocatalytic reduction of carbon dioxide to formate anion

Cited by 185 publications

References 0 publications

Reversible interconversion of carbon dioxide and formate by an electroactive enzyme

Reversible interconversion of carbon dioxide and formate by an electroactive enzyme

Splitting CO ₂ into CO and O ₂ by a single catalyst

Visible‐Light Photocatalytic Reduction of CO₂ to Formic Acid with a Ru Catalyst Supported by N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine Ligands

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Formation of a metal-hydride bond and the insertion of carbon dioxide. Key steps in the electrocatalytic reduction of carbon dioxide to formate anion

Cited by 185 publications

References 0 publications

Reversible interconversion of carbon dioxide and formate by an electroactive enzyme

Reversible interconversion of carbon dioxide and formate by an electroactive enzyme

Splitting CO 2 into CO and O 2 by a single catalyst

Visible‐Light Photocatalytic Reduction of CO2 to Formic Acid with a Ru Catalyst Supported by N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine Ligands

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Splitting CO ₂ into CO and O ₂ by a single catalyst

Visible‐Light Photocatalytic Reduction of CO₂ to Formic Acid with a Ru Catalyst Supported by N,N′‐Bis(diphenylphosphino)‐2,6‐diaminopyridine Ligands