ionic exchange membranes for energy applications

The increasing energy demand has led to excessive greenhouse gas emissions, contributing to climate change. Greenhouse gases, especially carbon dioxide, are key drivers of global warming, and fossil fuels account for over 50% of global energy production. However, fossil fuels have significant drawbacks, including CO2 emissions, finite supply, and dependence on unreliable imports. As a result, there is a global push to research and develop alternative, climate-neutral fuels to replace fossil fuels. To address these environmental challenges, membrane technologies have emerged as promising solu- tions. These technologies rely on selective permeability, allowing only specific molecules or ions to pass through. Ion Exchange Membranes (IEMs) are a specific type of membrane which allow the passage of ions, while blocking co-ions. IEMs are increasingly being explored for innovative applica- tions in energy conversion and production, which can be classified into water-based applications and energy-based applications. This thesis investigates an application of each type: Reverse ElectroDial- ysis (RED) as an energy production method starting from seawater and Direct SeaWater Electrolysis (DSWE) for green hydrogen generation. The thesis begins by discussing various methods for blue energy harvesting, focusing on reverse elec- trodialysis, and on the materials used in IEMs. Graphene-based IEMs reinforced with aramid fibers to enhance mechanical performance were used for this application. Different Graphene Oxide (GO) and fiber concentrations were investigated to evaluate their impact on the membrane properties. The mem- branes were then characterized morphologically, physicochemically and electrochemically, in terms of permselectivity and ionic resistance. The potential of DSWE as an innovative approach for green hydrogen production was then adressed. A detailed overview of the materials used in fabricating for the IEMs and catalysts for the electrolysis process was provided and the performance of a commercial bipolar membrane for this kind of appli- cation was then evaluated. Special emphasis was placed on optimizing the cathode-side catalyst for the hydrogen evolution reaction (HER) of the experimental setup and exploring different deposition techniques and substrate materials at Wetsus, the European Center of Excellence for Water Technol- ogy in Leeuwarden, The Netherlands. Finally, the future scalability of membrane fabrication was discussed, including the potential of roll- to-roll processes, and prospects for meeting the European Union’s targets for sustainable hydrogen production through DSWE, such as using asymmetric bipolar membranes.