Role of ion-selective membranes in the carbon balance for CO₂ electroreduction via gas diffusion electrode reactor designs.

ABSTRACT: In this work, the effect of ion-selective membranes on the detailed carbon balance was systematically analyzed for high-rate CO₂ reduction in GDE-type flow electrolyzers. By using different ion-selective membranes, we show nearly identical catalytic selectivity for CO₂ reduction, which is primarily due to a similar local reaction environment created at the cathode/electrolyte interface via the introduction of a catholyte layer. In addition, based on a systematic exploration of gases released from electrolytes and the dynamic change of electrolyte speciation, we demonstrate the explicit discrepancy in carbon balance paths for the captured CO₂ at the cathode/catholyte interface via reaction with OH^- when using different ion-selective membranes: (i) the captured CO₂ could be transported through an anion exchange membrane in the form of CO₃ ^2-, subsequently releasing CO₂ along with O₂ in the anolyte, and (ii) with a cation exchange membrane, the captured CO₂ would be accumulated in the catholyte in the form of CO₃ ^2-, while (iii) with the use of a bipolar membrane, the captured CO₂ could be released at the catholyte/membrane interface in the form of gaseous CO₂. The unique carbon balance path for each type of membrane is linked to ion species transported through the membranes.

SUBMITTER: Ma M 

PROVIDER: S-EPMC8163407 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature