Enhanced kinetics of CO2 electro-reduction on a hollow gas bubbling electrode in molten ternary carbonates

Muxing Gao, Bowen Deng, Zhigang Chen, Meng Tao, Dihua Wang

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Electrochemical reduction of CO2 to value-added carbon and oxygen in lithium-containing molten carbonates at 723 K is a promising approach to the efficient utilization of CO2. It was recently reported that the cathodic process in this transformation is controlled by the sluggish diffusion of the generated O2− ions. The formation of Li2O on the cathode results in partial cathodic passivation of the cathode. To accelerate the reaction kinetics and also eliminate the concentration polarization of the resulting Li2O, the effect of bubbling CO2 through a hollow electrode was examined in this work using a home-made hollow gas bubbling (HGB) electrode. The localised CO2 bubbling not only accelerates the transport of O2− ions by agitating the electrolyte nearby, but the CO2 also reacts with Li2O to form the more soluble Li2CO3. Cyclic voltammetry (CV), linear sweep voltammetry (LSV) and constant current electrolysis were conducted in the melt at 723 K to study the depolarization mechanisms involved in the CO2 bubbling reaction. Using the HGB electrode, the steady-state current density increased from 15.3 mA/cm2 to ~200 mA/cm2 at a potential of −2.4 V (vs. Ag/Ag2SO4). The HGB electrode effectively improved the cathodic kinetics, which is beneficial for CO2 capture and electrochemical conversion.

Original languageEnglish (US)
Pages (from-to)81-84
Number of pages4
JournalElectrochemistry Communications
Volume100
DOIs
StatePublished - Mar 1 2019

Fingerprint

Carbonates
Molten materials
Gases
Electrodes
Kinetics
Cathodes
Ions
Depolarization
Voltammetry
Lithium
Electrolysis
Passivation
Reaction kinetics
Electrolytes
Cyclic voltammetry
Current density
Carbon
Polarization
Oxygen

Keywords

  • CO conversion
  • Electrode kinetics
  • Molten carbonates
  • Passivation

ASJC Scopus subject areas

  • Electrochemistry

Cite this

Enhanced kinetics of CO2 electro-reduction on a hollow gas bubbling electrode in molten ternary carbonates. / Gao, Muxing; Deng, Bowen; Chen, Zhigang; Tao, Meng; Wang, Dihua.

In: Electrochemistry Communications, Vol. 100, 01.03.2019, p. 81-84.

Research output: Contribution to journalArticle

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AU - Wang, Dihua

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AB - Electrochemical reduction of CO2 to value-added carbon and oxygen in lithium-containing molten carbonates at 723 K is a promising approach to the efficient utilization of CO2. It was recently reported that the cathodic process in this transformation is controlled by the sluggish diffusion of the generated O2− ions. The formation of Li2O on the cathode results in partial cathodic passivation of the cathode. To accelerate the reaction kinetics and also eliminate the concentration polarization of the resulting Li2O, the effect of bubbling CO2 through a hollow electrode was examined in this work using a home-made hollow gas bubbling (HGB) electrode. The localised CO2 bubbling not only accelerates the transport of O2− ions by agitating the electrolyte nearby, but the CO2 also reacts with Li2O to form the more soluble Li2CO3. Cyclic voltammetry (CV), linear sweep voltammetry (LSV) and constant current electrolysis were conducted in the melt at 723 K to study the depolarization mechanisms involved in the CO2 bubbling reaction. Using the HGB electrode, the steady-state current density increased from 15.3 mA/cm2 to ~200 mA/cm2 at a potential of −2.4 V (vs. Ag/Ag2SO4). The HGB electrode effectively improved the cathodic kinetics, which is beneficial for CO2 capture and electrochemical conversion.

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