The CO₂ electrolysis driven with renewable sources is a promising alternative to mitigate greenhouse gas emissions by converting CO₂ into valuable feedstocks and storing renewable electrical energy ¹. Membrane electrode assemblies (MEAs) equipped with gas diffusion electrodes (GDEs) have shown great potential to overcome the current limitation of aqueous-fed systems while bringing this technology to economically-competing levels ². In the last decade, many studies have been devoted to developing efficient catalyst materials and reactor designs; however, the effect of operating conditions such as temperature has not been thoroughly studied³. Given that the temperature affects CO₂ electrolysis in a complex way (simultaneous effects on the CO₂ diffusivity, solubility, the ionic conductivity of the membrane, and surface wettability of the GDE⁴), a systematic investigation is necessary to determine temperature influence on the product distribution

In this study, we investigate the temperature effects on CO₂ electrolysis of Cu-based GDEs in an MEA-based approach in a temperature range between 25 and 80˚C, to enhance the selectivity of C₂₊ products and the energy efficiency while suppressing the hydrogen evolution (HER) and the degradation of the GDE and the membrane. For this investigation, a robust system for controlling and measuring the temperature of all the system components was developed, and we simultaneously set up proper guidelines to perform these electrocatalytic temperature measurements in a consistent and reproducible way.

For evaluating the temperature influence on electrocatalytic performance, a series of electrochemical measurements such as linear sweep voltammetry (LSV), double-layer capacitance measurements (DLC), potentiostatic and galvanostatic experiments were performed. The obtained results provide insights into how CO₂ diffusion, reaction kinetics, and CO₂ mass transport vary with temperature and affect the overall performance. We observed improvement in reaction rates and a drop in cell voltages at higher temperatures due to the enhancement of membranes' ionic conductivity and water management. The experiments focused on selectivity and product crossover revealed a specific trend at temperatures above 60˚C for gas and liquid products, setting up the optimal conditions for a stable operation with higher faradaic efficiencies of carbon-based compounds.

1 A. Vasileff, Y. Zheng and S. Z. Qiao, Adv. Energy Mater., 2017, 7, 1–21.

2 T. Burdyny and W. A. Smith, Energy Environ. Sci., 2019, 12, 1442–1453.

3 B. Endrődi, G. Bencsik, F. Darvas, R. Jones, K. Rajeshwar and C. Janáky, Prog. Energy Combust. Sci., 2017, 62, 133–154.

4 A. Löwe, C. Rieg, T. Hierlemann, N. Salas, D. Kopljar, N. Wagner and E. Klemm, ChemElectroChem, 2019, 6, 4497–4506.