Molecular Catalysis of Electrochemical Reactions. Mechanistic Aspects

Savéant, Jean‐Michel

doi:10.1021/cr068079z

Cited by 861 publications

(739 citation statements)

References 454 publications

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“…Although CO 2 is a cheap, non-toxic and abundant potential carbon feedstock 1 , it is difficult to reduce to more useful forms due to its thermodynamic stability and kinetic inertness. Approaches to activating and reducing CO 2 by electrochemical and electrocatalytic methods in the presence of transition metals and their alloys have been reviewed extensively [2][3][4][5][6][7][8][9][10] . An attractive scheme for CO 2 reduction should be able to function under the mildest possible reaction conditions.…”

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confidence: 99%

RETRACTED ARTICLE: Reduction of carbon dioxide to oxalate by a binuclear copper complex

2014

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confidence: 99%

RETRACTED ARTICLE: Reduction of carbon dioxide to oxalate by a binuclear copper complex

2014

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“…As examples, specific models have accounted for MichaelisMenten concentration and rotation-rate dependencies (12,13), diode-like behavior (14), irreversible electrocatalytic voltammetry (15), dispersion of electronic couplings between electrode and enzyme (16,17), and the influence of intramolecular electron transfer rates (18). These models are all variations on the classical procedure of treating electrocatalytic reactions as a special type of coupled electrochemical (EC) process (19,20 (8). Both EcHyd1 and EcHyd2 are membrane-bound enzymes in vivo and have membrane-extrinsic domains (the soluble, electrocatalytically active forms) that project into the periplasm.…”

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confidence: 99%

Electrocatalytic mechanism of reversible hydrogen cycling by enzymes and distinctions between the major classes of hydrogenases

Hexter

Grey

Happe

et al. 2012

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

156

223

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The authors note that on page 11517, right column, fourth full paragraph, lines 4-5, "k min = k 0 and k max = k 0 exp(−βd 0 )" should instead appear as "k max = k 0 and k min = k 0 exp(−βd 0 )." Also, on page 11518, left column, fourth full paragraph, line 8, "e 2 = k 2a /k 2c " should instead appear as "e 2 = k 2c /k 2a ."Figs. 4, 5, and 6 and the legend for Figure 5 appeared incorrectly. The corrected figures and their legends appear below.

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“…2 A and C-specifically the irreversible catalytic wave and subsequent reversible waveare reminiscent of what Savéant classifies as "total catalysis." (41,42) This term denotes a mechanistic regime wherein, owing to a high catalytic rate and/or a dearth of reactant, the rate of reactant consumption is very rapid, leading to control of the electrocatalytic response by diffusion of the reactant from the bulk electrolyte. This behavior results in the presence of two waves: (i) an irreversible wave involving the reactant-diffusion-controlled catalytic process, followed by (ii) a reversible wave associated with the molecular catalyst, centered at the potential where it appears in the absence of reactant.…”

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confidence: 99%

Role of pendant proton relays and proton-coupled electron transfer on the hydrogen evolution reaction by nickel hangman porphyrins

Bediako

Solis

Dogutan

et al. 2014

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

181

204

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The hangman motif provides mechanistic insights into the role of pendant proton relays in governing proton-coupled electron transfer (PCET) involved in the hydrogen evolution reaction (HER). We now show improved HER activity of Ni compared with Co hangman porphyrins. Cyclic voltammogram data and simulations, together with computational studies using density functional theory, implicate a shift in electrokinetic zone between Co and Ni hangman porphyrins due to a change in the PCET mechanism. Unlike the Co hangman porphyrin, the Ni hangman porphyrin does not require reduction to the formally metal(0) species before protonation by weak acids in acetonitrile. We conclude that protonation likely occurs at the Ni(I) state followed by reduction, in a stepwise proton transfer-electron transfer pathway. Spectroelectrochemical and computational studies reveal that upon reduction of the Ni(II) compound, the first electron is transferred to a metal-based orbital, whereas the second electron is transferred to a molecular orbital on the porphyrin ring.renewable | solar fuels | electrocatalysis S olar-to-fuels conversions provide a path to harnessing the ubiquitous albeit intermittent renewable energy resource offered by the sun (1-6). Efficient catalysis of transformations of energy consequence (7-13) mandates the coupling of electron transfer (ET) to proton transfer (PT) in proton-coupled electron transfer (PCET) reactions (14)(15)(16)(17)(18)(19)(20). In the absence of PCET, intermediates possessing equilibrium potentials that are prohibitively large depreciate the storage capacity offered by the solarto-fuels conversion process. The coupling of protons to changes in electron equivalency offers the possibility of restricting the equilibrium potentials of the redox steps to a more narrow potential range, thereby minimizing the overpotential required to sustain catalysis at a desired turnover rate. Thus, the exploitation of PCET pathways to permit potential-leveling effects is a crucial prerequisite for the efficient catalytic conversion reactions of energy relevant molecules.PCET reactions may be classified into stepwise and concerted pathways (14,16,20,21). Stepwise PCET may involve ET first followed by PT (ETPT), or PT followed by ET (PTET). In concerted proton-electron transfers (CPET), the proton and electron traverse a common transition state. Whereas concerted pathways avoid the formation of thermodynamically costly intermediates, CPET reactions may incur kinetic penalties associated with the requirements for proton tunneling (19,20,22). The competition between these dynamics during catalysis determines the most efficient route of reaction. Studies that explore the interplay between these factors are crucial to designing catalytic reactions of high efficiency. Along these lines, the incorporation of proton relays in the second coordination sphere of molecular catalysts has emerged as a useful tool in optimizing PCET transformations (23-29). We have focused on the synthesis and mechanistic investigation of a class of me...

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Molecular Catalysis of Electrochemical Reactions. Mechanistic Aspects

Cited by 861 publications

References 454 publications

RETRACTED ARTICLE: Reduction of carbon dioxide to oxalate by a binuclear copper complex

RETRACTED ARTICLE: Reduction of carbon dioxide to oxalate by a binuclear copper complex

Electrocatalytic mechanism of reversible hydrogen cycling by enzymes and distinctions between the major classes of hydrogenases

Role of pendant proton relays and proton-coupled electron transfer on the hydrogen evolution reaction by nickel hangman porphyrins

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