Belgium, Brussels — 9 December 2025 — A key discovery for the European Union energy production was made by the researchers from the Technical University of Denmark (DTU) in the framework of the research for ECO2Fuel technology: they have shown that short-side-chain perfluorosulfonic acid (SSC-PFSA e.g. Aquivion®) membranes renown for their high structural crystallinity, enhanced thermomechanical resilience and superior water retention behavior – can maintain the proton conductivity at temperatures up to 150 °C under elevated pressure and humidification. Notably, the membrane degradation is driven more strongly by humidity than by temperature or open-circuit-voltage cycling, which act as comparatively gentler stressors. This insight opens new horizons for proton exchange membranes in CO₂ electrolysis, water splitting, and fuel cells, where higher operating temperatures promise faster kinetics, improved efficiency, simplified system design, and prospects for alternative catalyst materials.
CO₂ conversion, a game-changer technology for the EU decarbonisation strategy
- The discovery supports the EU’s Green Deal and Hydrogen Strategy by advancing cleaner, more efficient electrochemical technologies essential for achieving climate neutrality by 2050.
- Strengthens Europe’s leadership in sustainable materials science and energy innovation, helping to reduce reliance on imported fossil fuels and critical materials.
- It directly contributed to the EU’s goals of enabling CO₂ conversion and decarbonising hard-to-abate industrial sectors.
A high temperature resistance
The researchers found that SSC-PFSA membranes can maintain their structural integrity and proton conductivity at temperatures above the boiling point of water. When the system is pressurised, dehydration of the membrane is reduced, allowing ionic conductivity to remain high even beyond 100 °C. By operating at elevated temperatures, the single-phase gaseous system could simplify system design and improve reaction behaviour. Additionally, the membrane remains dense, which leads to lower crossover of CO2 reduction products. This is beneficial for both efficiency and safety. However, the study also showed that frequent cycling between dry and humid conditions poses a significant stress on the material and can accelerate membrane degradation, highlighting the need for careful humidity management.
“The aim of this study was to determine whether SSC-PFSA membranes can truly enable high-temperature electrochemical operation”, said Professor Qingfeng Li, a researcher specialised in hydrogen and fuel cell technologies from DTU, “These membranes do not soften in the same way as traditional Nafion when heated above 100 °C, which makes them promising candidates for systems operating in the 110–120 °C range”.
Although this membrane was investigated as a candidate within the ECO2Fuel research, the team later selected anion exchange membranes as the final technology pathway. The findings of this study remain valuable as fundamental knowledge and can be applied in water electrolysers technology, fuel cells production, and future CO₂ conversion systems.
Strategic Context
Although the membrane characterised in this study ultimately was not selected as the final material for the technology the results provide valuable design and performance insight for the development of next-generation proton and ion-exchange membranes suited to high-temperature industrial environments.
Read the full scientific paper here: https://www.sciencedirect.com/science/article/pii/S0167273824002959?via%3Dihub
