Enhanced kinetics of CO 2 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 journalArticlepeer-review

6 Scopus citations

Abstract

Electrochemical reduction of CO 2 to value-added carbon and oxygen in lithium-containing molten carbonates at 723 K is a promising approach to the efficient utilization of CO 2 . It was recently reported that the cathodic process in this transformation is controlled by the sluggish diffusion of the generated O 2− ions. The formation of Li 2 O 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 Li 2 O, the effect of bubbling CO 2 through a hollow electrode was examined in this work using a home-made hollow gas bubbling (HGB) electrode. The localised CO 2 bubbling not only accelerates the transport of O 2− ions by agitating the electrolyte nearby, but the CO 2 also reacts with Li 2 O to form the more soluble Li 2 CO 3. 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 CO 2 bubbling reaction. Using the HGB electrode, the steady-state current density increased from 15.3 mA/cm 2 to ~200 mA/cm 2 at a potential of −2.4 V (vs. Ag/Ag 2 SO 4 ). The HGB electrode effectively improved the cathodic kinetics, which is beneficial for CO 2 capture and electrochemical conversion.

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

Keywords

  • CO conversion
  • Electrode kinetics
  • Molten carbonates
  • Passivation

ASJC Scopus subject areas

  • Electrochemistry

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