Kinetic studies of the electrolytic reduction of carbon dioxide on the mercury electrode

Paik, Woon‐kie; Andersen, Terrell N.; Eyring, Henry

doi:10.1016/0013-4686(69)87019-2

Cited by 173 publications

(123 citation statements)

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“…The CO 2 radical has been experimentally observed on other metals, and it is inferred that it also forms on copper. (18,34,37,38) If we assume that the surface coverage of the CO 2 radical θ ≪ 1, consistent with the observation that copper surfaces are predominantly covered in CO under CO 2 reduction conditions, (39)(40)(41) as a methanation current, is (3) where n is the total number of electron transfers needed to convert CO 2 1 to methane 5 and k 2 is the rate constant for the conversion of 2 to 3. Combining eqs 2 and 3, we obtain (4) This rate law is consistent with the second-order dependence on CO 2 partial pressure that we experimentally observe.…”

Section: Continuum From Nanoparticle-like To Foil-like Behaviorsupporting

confidence: 69%

“…We find an unusual second-order (2.03 ± 0.08) dependence of methanation current on CO 2 partial pressure for the n-Cu/C catalyst ( Figure 5B). (33) Based on work on other metals, such as gold (9) and mercury, (34) it is often assumed that CO 2 reduction on copper foils proceeds with a first-order dependence on CO 2 in aqueous electrolytes, (35,36) although we observe an ill-defined order ( Figure 5B). The methanation current on the n-Cu/C catalyst exhibits no clear order dependence on sodium bicarbonate concentration ( Figure S3), although optimization of the buffer concentration can further enhance Faradaic efficiencies for methanation by approximately 10% (Supporting Information).…”

Section: Continuum From Nanoparticle-like To Foil-like Behaviormentioning

confidence: 66%

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Enhanced Electrochemical Methanation of Carbon Dioxide with a Dispersible Nanoscale Copper Catalyst

2014

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Although the vast majority of hydrocarbon fuels and products are presently derived from petroleum, there is much interest in the development of routes for synthesizing these same products by hydrogenating CO 2 . The simplest hydrocarbon target is methane, which can utilize existing infrastructure for natural gas storage, distribution, and consumption. Electrochemical methods for methanizing CO 2 currently suffer from a combination of low activities and poor selectivities. We demonstrate that copper nanoparticles supported on glassy carbon (n-Cu/C) achieve up to 4 times greater methanation current densities compared to high-purity copper foil electrodes. The n-Cu/ C electrocatalyst also exhibits an average Faradaic efficiency for methanation of 80% during extended electrolysis, the highest Faradaic efficiency for room-temperature methanation reported to date. We find that the level of copper catalyst loading on the glassy carbon support has an enormous impact on the morphology of the copper under catalytic conditions and the resulting Faradaic efficiency for methane. The improved activity and Faradaic efficiency for methanation involves a mechanism that is distinct from what is generally thought to occur on copper foils. Electrochemical data indicate that the early steps of methanation on n-Cu/C involve a pre-equilibrium one-electron transfer to CO 2 to form an adsorbed radical, followed by a rate-limiting nonelectrochemical step in which the adsorbed CO 2 radical reacts with a second CO 2 molecule from solution. These nanoscale copper electrocatalysts represent a first step toward the preparation of practical methanation catalysts that can be incorporated into membrane-electrode assemblies in electrolyzers.

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Section: Continuum From Nanoparticle-like To Foil-like Behaviorsupporting

confidence: 69%

Section: Continuum From Nanoparticle-like To Foil-like Behaviormentioning

confidence: 66%

Enhanced Electrochemical Methanation of Carbon Dioxide with a Dispersible Nanoscale Copper Catalyst

2014

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“…A number of studies have shown that one way of influencing the product distribution is through changes in the electrolyte cation. [8][9][10][11][12][13] The role of cations is particularly interesting because a number of studies have shown that both the activity and selectivity of Ag, Hg, and Cu for the CO 2 reduction reaction (CO 2 RR) are influenced significantly by the size of the alkali metal cation in the electrolyte. [8][9][10][11][12][13] Similar effects have also been observed for the electrochemical reduction of oxygen, the oxidation of hydrogen, and the oxidation of low molecular weight alcohols.…”

Section: Introductionmentioning

confidence: 99%

“…[8][9][10][11][12][13] The role of cations is particularly interesting because a number of studies have shown that both the activity and selectivity of Ag, Hg, and Cu for the CO 2 reduction reaction (CO 2 RR) are influenced significantly by the size of the alkali metal cation in the electrolyte. [8][9][10][11][12][13] Similar effects have also been observed for the electrochemical reduction of oxygen, the oxidation of hydrogen, and the oxidation of low molecular weight alcohols. [14][15][16][17][18] For Ag and Hg, which are selective for CO 2 reduction to carbon monoxide (CO) and formate anions (HCOO -), respectively, increasing the alkali metal cation size increases the rates of formation of these products.…”

Section: Introductionmentioning

confidence: 99%

“…[14][15][16][17][18] For Ag and Hg, which are selective for CO 2 reduction to carbon monoxide (CO) and formate anions (HCOO -), respectively, increasing the alkali metal cation size increases the rates of formation of these products. 8,10,11 For Cu, increasing alkali metal size leads to higher selectivities to C 2 products, e.g., ethylene and ethanol. 9,12,13 Explanations for these phenomena have been attributed to differences in local pH, or differences in kinetic overpotentials due to the electrochemical potential in the outer Helmholtz plane being affected by cation size.…”

Section: Introductionmentioning

confidence: 99%

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Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide

et al. 2017

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The electrochemical reduction of CO 2 is known to be influenced by the identity of the alkali metal cation in the electrolyte; however, a satisfactory explanation for this phenomenon has not been developed. Here we present the results of experimental and theoretical studies aimed at elucidating the effects of electrolyte cation size on the intrinsic activity and selectivity of metal catalysts for the reduction of CO 2 . Experiments were conducted under conditions where the influence of electrolyte polarization is minimal in order to show that cation size affects the intrinsic rates of formation of certain reaction products, most notably for HCOO The observed trends in activity with cation size are attributed to an increase in the concentration of cations at the outer Helmholtz plane with increasing cation size.

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CO₂‐reduction, catalyzed by metal electrodes

Hori

2010

Handbook of Fuel Cells

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The electrochemical reduction of CO 2 proceeds in aqueous electrolytes with large overpotential, since the first step of the CO 2 reduction, i.e., CO 2 − anion radical formation, requires highly negative potential. The product distribution from the CO 2 reduction depends greatly on the electrode metal. Cu yields CH 4 , C 2 H 4 and alcohols; Au, Ag and Zn give CO as the main product; Pb, Hg, In, Sn, Cd and Tl form HCOO − ; Ni, Fe and Pt do not reduce CO 2 whereas H 2 evolves from the electrolysis of H 2 O. The reason is rationalized in terms of the adsorption of CO 2 − anion radical on the electrode metals. The CO 2 reduction at the single crystal electrodes of Cu and Pt metals is summarized, and the mechanism of the hydrocarbon formation at Cu electrode is discussed in detail. The rate of CO 2 reduction is enhanced by increased transport of CO 2 to the electrode; such as the solid polymer electrolytes, the gas diffusion electrodes, the electrolyses under high pressure or in nonaqueous electrolytes.

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Kinetic studies of the electrolytic reduction of carbon dioxide on the mercury electrode

Cited by 173 publications

References 19 publications

Enhanced Electrochemical Methanation of Carbon Dioxide with a Dispersible Nanoscale Copper Catalyst

Enhanced Electrochemical Methanation of Carbon Dioxide with a Dispersible Nanoscale Copper Catalyst

Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide

CO₂‐reduction, catalyzed by metal electrodes

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Kinetic studies of the electrolytic reduction of carbon dioxide on the mercury electrode

Cited by 173 publications

References 19 publications

Enhanced Electrochemical Methanation of Carbon Dioxide with a Dispersible Nanoscale Copper Catalyst

Enhanced Electrochemical Methanation of Carbon Dioxide with a Dispersible Nanoscale Copper Catalyst

Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide

CO2‐reduction, catalyzed by metal electrodes

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Product

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CO₂‐reduction, catalyzed by metal electrodes