Stability and O 2 sensitivity of CO 2 electrolysers Caitlin Muir , Bhavin Siritanaratkul, Alex Cowan Stephenson Institute for Renewable Energy and Department of Chemistry, University of Liverpool Liverpool, UK Carbon Dioxide reduction electrolysers can use industry emissions as their feedstock. Previous experiments have been carried out using pure CO 2 whilst optimising the electrolyser components. Using industry captured CO 2 introduces impurities such as SO 2 , NO and O 2 . 1 O 2 impurities can also be introduced from water oxidation at the anode, where the generated O 2 can mix with the crossed-over CO 2 , resulting in the need for a separation step before this CO 2 stream can be reused. Separation of the gases can be a time and energy intensive process. However, if an electrolyser has an impurity threshold, less time and energy is needed to purify the flue gas. Experimental work was carried out to investigate the effect O 2 has on the reduction of CO 2 at various concentrations, with the aim of investigating the stability and CO 2 selectivity of BPM and AEM electrolysers with the presence of O 2 impurities in the gas feed. The electrolyser with a pure CO 2 gas feed was initially used to optimise the system and assess the stability. Next, various concentrations of O 2 were included in the pure CO 2 gas stream.
Figure 1 Faradaic efficiency for CO (blue), H 2 (green) and O 2 RR (grey) for the BPM electrolyser at various O 2 concentrations in CO 2 with an applied current of 100 mA cm -2 The resulting faradaic efficiencies showed how even 1% O 2 can have a significant impact on FE CO. At 100 mA cm -2 with 1% O 2 , the FE CO decreased from around 75% initially, to an average of 40%. At 2% O 2 , the FE CO further decreases to almost 0% - showing the significant impact O 2 impurities have on product selectivity. Moving forward, other catalysts could be explored to see if they have a different tolerance towards flue gas impurities, and the operating current densities could be improved towards the typical industry minimum of 200 mA cm -2 . References 1. Van Daele, L. Hintjens, S. Hoekx, B. Bohlen, S. Neukermans, N. Daems, J. Hereijgers and T. Breugelmans, Applied Catalysis B: Environmental , 2024, 341 , 123345
P66
© The Author(s), 2025
Made with FlippingBook Learn more on our blog