Electrochemically active species and multielectron processes in ionic melts

Shapoval, V. I.; Solov'ev, V. V.; Малышев, В. В.

doi:10.1070/rc2001v070n02abeh000619

Cited by 20 publications

(9 citation statements)

References 49 publications

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“…As previously noted, potassium carbonate will yield solid carbon under high carbon dioxide pressure but tends to form potassium metal under ambient pressures. 9 High pressure of CO 2 was the key to deposit a carbon product onto cathode during electrolysis of NaCl/KCl eutectics, in accord with the carbon formation reaction eq 8. 35 It is interesting to investigate the thermodynamic influence of pressure of CO 2 toward products.…”

Section: Resultsmentioning

confidence: 84%

The Minimum Electrolytic Energy Needed To Convert Carbon Dioxide to Carbon by Electrolysis in Carbonate Melts

et al. 2015

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One pathway to remove the greenhouse gas carbon dioxide to mitigate climate change is by dissolution and electrolysis in molten carbonate to produce stable, solid carbon. This study determines critical knowledge to minimize the required electrolysis energy, the reaction stoichiometry in which carbon and O 2 are the principal products, and that CO 2 can be electrolyzed inexpensively. Thermochemical and experimental results indicate that the principal carbon-deposition reaction in molten Li 2 CO 3 or Li 2 O/Li 2 CO 3 electrolytes at 750°C is Li 2 O + 2CO 2 → Li 2 CO 3 + C + O 2 . The reaction occurs at high Faradaic efficiency of the 4e − reduction of CO 2 to carbon and oxygen at an electrolysis voltage as low as <1 V. Electrolytes without lithium carbonate but containing calcium and/or barium carbonate can also be employed as reaction media for successful carbon deposition, e.g. in an Na/BaCO 3 melt. However, the electrolysis reduction in pure Na or K or Na/K carbonate eutectics at 1 atm of CO 2 forms metals and/or gases, i.e., CO.

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Section: Resultsmentioning

confidence: 84%

The Minimum Electrolytic Energy Needed To Convert Carbon Dioxide to Carbon by Electrolysis in Carbonate Melts

et al. 2015

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“…In quantum chemical studies of this kind, the main approach is calculation of the parameters of model systems including an anion complex with an outer spheric (OS) cation shell [20][21][22][23][24]. It was shown, using the nM + [NbF 7 ], nM + [CrCl 6 ] (n = 1 -n lim ), and other systems, that the highest thermodynamic stability is inherent in compositions with a certain intermediate number of OS cations n < n lim , where n lim is the limit ing number of OS cations held by the given complex [21,22,24].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical and quantum-chemical studies of chromium(III,II) fluoride complexes in alkali chloride melts

2014

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815Previously, we studied the effect of the second coordination sphere on k s in chloride melts [17,18]. The NaCl-KCl-CrCl 3 , KCl-CrCl 3 , and CsCl-CrCl 3 systems were studied. It was shown that the standard rate constants of charge transfer increased at elevated Abstract-The standard rate constants (k s ) of charge transfer on a glass carbon electrode were determined for the Cr(III)/Cr(II) redox pair in the NaCl-KCl-K 3 CrF 6 , KCl-K 3 CrF 6 , and CsCl-K 3 CrF 6 systems at 973-1173 K by cyclic voltammetry. The k s constant was found to increase at elevated temperatures and the follow ing nonmonotonic dependence of k s on the nature of the outer spheric cation was found: k s (CsCl) > k s (NaCl-KCl) > k s (KCl). On the basis of quantum chemical data for the M 3 CrF 6 + 18MCl (M = Na, K) model systems, it was shown that the complex chromium particles with four or five outer spheric sodium or potassium cations had maximum thermodynamic stability. Quantum chemical calculations were performed to interpret the experimental data on the effect of the second coordination sphere of the complexes on the standard charge transfer rate constants.

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“…Previously [1][2][3][4] lim is the limiting number of OS cations bound to a given complex, are thermodynamically most stable. Such systems (designating them as the type I system) are often used for modeling of the charge transfer process in melts [5][6][7][8][9]. The activation energy of electron transfer is estimated here based on Marcus theory [10].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Model Systems (M⁺)_n·[CrX₆³⁻] and M₃CrX₆+ 18MX Based on Quantum-Chemical Calculations (X: F, Cl)

Kremenetsky

Kuznetsov

2016

Journal of Chemistry

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On the basis of quantum-chemical calculations the most stable particle compositions are estimated in such model systems as (M+)n·[CrCl6] and M3CrCl6+ 18MCl (M = Na, K, and Cs). In all systems these particles are positively charged. For systems (M+)n·[CrCl6], (M+)n·[CrF6], M3CrF6+ 18MCl, M3CrF6+ 18MF, and M3CrCl6+ 18MCl (M = Na, K, and Cs) a number of energy parameters characterizing the state of the system before and after electron transfer are calculated. The results indicate the possibility of electron transfer from the cathode to the melt system, which is in the initial state. However, this possibility cannot be realized in systems where LUMOs (lowest unoccupied molecular orbitals) have purely ligand character. In this case, the preliminary deformation of a cationic shell of electroactive species is required; it transforms the initial system to the transition state. However, in all considered systems the search of the transition state should be carried close to the initial statePi. This greatly simplifies a problem and transforms it from a purely theoretical sphere to the field of practical tasks that do not require exceptional cost of computer time.

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Electrochemically active species and multielectron processes in ionic melts

Cited by 20 publications

References 49 publications

The Minimum Electrolytic Energy Needed To Convert Carbon Dioxide to Carbon by Electrolysis in Carbonate Melts

The Minimum Electrolytic Energy Needed To Convert Carbon Dioxide to Carbon by Electrolysis in Carbonate Melts

Electrochemical and quantum-chemical studies of chromium(III,II) fluoride complexes in alkali chloride melts

Comparison of Model Systems (M⁺)_n·[CrX₆³⁻] and M₃CrX₆+ 18MX Based on Quantum-Chemical Calculations (X: F, Cl)

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Electrochemically active species and multielectron processes in ionic melts

Cited by 20 publications

References 49 publications

The Minimum Electrolytic Energy Needed To Convert Carbon Dioxide to Carbon by Electrolysis in Carbonate Melts

The Minimum Electrolytic Energy Needed To Convert Carbon Dioxide to Carbon by Electrolysis in Carbonate Melts

Electrochemical and quantum-chemical studies of chromium(III,II) fluoride complexes in alkali chloride melts

Comparison of Model Systems (M+)n·[CrX63−] and M3CrX6+ 18MX Based on Quantum-Chemical Calculations (X: F, Cl)

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Comparison of Model Systems (M⁺)_n·[CrX₆³⁻] and M₃CrX₆+ 18MX Based on Quantum-Chemical Calculations (X: F, Cl)