New Co-Electrolysis Cell Design with Improved CO2 Reduction Efficiency

Abstract

Electrochemical CO2 reduction it is an attractive method for minimizing the level of atmospheric CO2 and storing energy 1 , 2. When this process is coupled to a renewable energy source such as wind or solar, carbon dioxide is converted to fuels or chemical feedstock. To reduce important quantities of CO2, specific devices named co-electrolyser are needed. For high efficiency of these devices several parameters need to be integrated: i) active cathode catalyst for CO2 reduction reaction (CO2RR), ii) optimal cathode pH, iii) adequate polymer electrolytes when the CO2RR takes place from gas phase and iv) rational engineering for low energy consumption. Our work presents the design of a new co-electrolysis cell operating at low temperature (i.e. 40°C) where not liquid electrolyte is used for CO2RR. This new cell configuration made use of a standard Nafion® cation exchange membrane in combination with a modified cathode catalyst layer preparation: an alkaline anion exchange ionomer was used within the cathode catalyst layer, and an additional thin film of the same alkaline ionomer was coated on the cathode catalyst layer in order to prevent direct contact between the cathode catalyst and the acidic cation exchange membrane. Different types of silver catalysts are investigated under this configuration 3. The cells faradaic and energetic efficiencies are compared with those obtained for the same catalysts in standard three electrode cells using liquid electrolytes4. References J. Durst et al., Chimia, 69, 769–776 (2015).J. Herranz et al., Nano Energy, 29 (2016).A. Dutta, M. Rahaman, N. C. Luedi, M. Mohos, and P. Broekmann, ACS Catal., 6, 3804–3814 (2016).K. P. Kuhl, E. Cave, D. N. Abram, and T. F. Jaramillo, Energy Environ. Sci., 5, 7050–7059 (2012). Acknowledgements Financial support of this work by the Swiss Innovation Agency (Innosuisse) and the Swiss Competence Center for Energy Research Heat and Electricity Storage are greatly acknowledged.