Stability and performance studies of CO2 reduction on silver nanoparticles in bipolar and bipolar-like co-electrolysis systems
Bernhard Pribyl-Kranewitter a, Alexandra Pătru a, Thomas Justus Schmidt a b
a Electrochemistry Laboratory, Paul Scherrer Institut, Villigen PSI, 5232, Switzerland
b Laboratory of Physical Chemistry, ETH Zürich, Switzerland
Poster, Bernhard Pribyl-Kranewitter, 022
Publication date: 7th June 2020

Electrochemical CO2 reduction (CO2RR) must be carried out in a highly selective and efficient way to become an attractive option for the reduction of atmospheric CO2 as well as for renewable energy storage [1]. CO2RR can be sustained at the cathode side of a co-electrolysis system - ideally directly from gas phase - while oxygen is evolved at the anode side [2]. Our research efforts are focused on the design of such a co-electrolysis system using silver as CO2RR catalyst and operating at high-current densities with good faradaic efficiencies (FE) for CO. We have developed a novel cell (NC) configuration based on a bipolar membrane (BPM) configuration, which exhibits improved energetic efficiencies as well as significantly reduced crossover of carbonate and bicarbonate to the anode [3]. The latter leads to a reduced formation of CO2 on the anode side, avoiding inefficiencies resulting from the anodic CO2 formation observed in other systems [4].

The present work compares the performances of BPM and NC systems, focusing on the influence of potential, ionomer choice and cathode gas feed humidity on faradaic efficiencies and current density. Most recently, systemic stability issues have been identified in both system types via prolonged chronoamperometric experiments at different cell potentials, which have yet to be fully understood. Gas analysis was performed using gas chromatography in parallel with online mass spectrometry, employing a new calibration method capable of distinguishing between CO2, N2 and CO [5].

The authors thank the Swiss Innovation Agency Innosuisse and the Swiss Competence Center for Energy & Mobility Research (SCCER) for the funding of this project.

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