Innovative sulfonated chitosan membranes: bridging the gap in fuel cell technology

Abstract Chitosan, a natural polymer, is gaining attention for its low cost, hydrophilicity, and environmental benefits, making it a promising material for polyelectrolyte membranes (PEMs) in fuel cells (FCs). In this study, four membranes were fabricated using sulfonated chitosan combined with three sulfonated nanoparticles: sulfonated titanium dioxide (STiO 2 ), sulfonated silicon dioxide (SSiO 2 ), and sulfonated carbon nanotubes (SCNT) in varying ratios. The optimal membrane was prepared using a specific ratio of these components, cross-linked with 0.5% glutaraldehyde. While the electrochemical performance improved with increasing nanoparticle ratios, excessive nanoparticle content led to diminished results. The optimal membrane demonstrated excellent stability at 50 °C, achieving a maximum power density of 90 mW/cm 2 at 280 mA/cm 2 and a low cell resistance of 5.1 Ω cm 2 . Compared to the chitosan (CS)-based membranes in the literature, the optimal membrane exhibited superior ion exchange capacity, proton conductivity, mechanical stability, and lower water uptake, highlighting its potential as a sustainable and high-performance proton exchange membrane in fuel cell applications.