Membrane-free electrolysis for low-voltage co-production of hydrogen and 2,5-furandicarboxylic acid

Electrolysis powered by renewable electricity has the potential to defossilise the production of chemicals and fuels. However, existing systems are hampered by high costs stemming from electricity consumption and low-value product streams, which restrict widespread adoption. Here, we propose a strategy to simultaneously lower the voltage and increase revenue of alkaline electrolysers by exchanging oxygen evolution for the electrosynthesis of a high-value sustainable building block, 2,5-furandicarboxylic acid (FDCA). By conducting selective FDCA production at high reaction rates, we demonstrate that devices can operate without the need for a membrane/separator, simplifying the configuration to improve performance. Through optimisation of catalysts, conditions, and device configuration, we showcase a membrane-free setup that can achieve a current density of 0.5 A cm−2 with a full-cell voltage < 1.5 V. This conceptual validation of the design and operation of membrane-free alkaline electrolysers paves the way for application of such architectures in emerging sustainable technologies.