Enhanced proton conductivity in a Cu-BTC thin-film membrane through lysine incorporation and a mixed matrix membrane

To meet the growing demand for clean and sustainable energy, the development of high-performance proton conductive materials is crucial for practical applications in PEMFCs. However, the current materials suffer from issues such as low conductivity, poor durability, and unclear structure-activity relationship. To address these challenges, we investigate the proton conductivity properties of lysine-decorated Cu-BTC (where BTC is benzene-1,3,5-tricarboxylate) and its corresponding thin-film membrane. We explore the impact of lysine (Lys) content (10 wt%, 20 wt%, 30 wt%, and 40 wt%) on the proton conductivity performance under varying humidity and temperature conditions. Our findings show that Cu-BTC-Lys (40 wt%) exhibits the best conductivity of 1.2 x 10(-3) S cm(-1) at 80 & DEG;C under 100% relative humidity (RH), aided by an activation energy (E-a) of 0.25 eV facilitating proton transfer through hydrogen-bonding networks via the Grotthuss mechanism. We then create a proton conductive membrane by fabricating Cu-BTC-Lys (40 wt%) with the PVP/PVDF polymeric matrix. The resulting Cu-BTC-Lys@PVP/PVDF-20 membrane shows a significantly improved conductivity of 4.8 x 10(-3) S cm(-1) at 80 & DEG;C under 100% RH, along with a decreasing E-a value of 0.15 eV. The membrane retains its rich hydrogen-bonding networks and excellent performance durability for up to 5 days, making it an ideal candidate for real-life applications.