Solar-Driven MOF Membrane Fabrication from Waste for Sustainable Separations

Membrane-based separations are among the most energy-efficient alternatives to conventional processes such as distillation, yet the fabrication of high-performance membranes remains energy- and resource-intensive. Metal–organic framework (MOF) membranes offer exceptional selectivity and tunability for demanding separations, including propylene/propane (C₃H₆/C₃H₈) and lithium/magnesium (Li⁺/Mg²⁺), but current hydro/solvothermal fabrication methods require high temperatures, pressures, grid electricity, and purified chemical precursors. This project, SUN-MEM, introduces a solar-driven photoelectrochemical (PEC) platform for MOF membrane fabrication under ambient conditions, eliminating external electrical input and enabling off-grid operation. The method directly integrates waste valorisation by using zinc ions recovered from spent Zn–Mn batteries and terephthalic acid (TPA) from PET plastic waste as precursors. Solar illumination simultaneously drives anodic and cathodic interfacial reactions, lowering nucleation barriers, enabling rapid growth within one hour, and producing valuable H2 and O2 by-products. The approach is compatible with both imidazolate (ZIF-8) and carboxylate (UiO-66) chemistries, demonstrated on flat plate and hollow fiber substrates for industrial scalability. Compared with conventional synthesis, SUN-MEM can reduce electricity consumption by over 95%, precursor costs by 65%, and manufacturing CO2 emissions by 84%, while contributing to the upcycling of over 4.9 Mt PET and 34 kt battery waste generated annually in the EU. By bridging solar energy conversion, MOF membrane engineering, and circular economy principles, the project delivers a disruptive route to sustainable, energy-autonomous membrane manufacturing, aligned with the EU Green Deal and Zero Pollution Ambition, and enabling equitable access to advanced separations in resource-limited regions.