Microporous Layer Design for Active DMFC Using CNF‐TiO ₂ Integration to Mitigate Methanol Crossover and Improve Power Density

ABSTRACT Direct Methanol Fuel Cells (DMFCs) are attractive for portable applications but face persistent challenges, including methanol crossover, poor catalyst layer adhesion, and inefficient mass transport associated with conventional microporous layers (MPLs). These deficiencies limit catalyst utilization and water management, resulting in reduced power output and stability. To address these challenges, this study developed a titanium dioxide–carbon nanofiber (TiO 2 –CNF) hybrid MPL via slurry seeping fabrication. The composite structure leverages CNF's high conductivity and TiO 2 ’s catalytic stability to achieve optimized porosity (69.85%) and balanced micro/mesopore distribution. Electrochemical testing revealed a 17.58% enhancement in peak power density at 4 M methanol concentration compared with CNF‐based MPLs, alongside a reduction in crossover‐induced losses from 71.9% to 39.46%. The CNF–TiO 2 interface promoted efficient charge transfer, maintained stable operation, and improved reactant/product transport, thereby enhancing overall DMFC efficiency. These results demonstrate that the TiO 2 –CNF hybrid MPL provides a robust and scalable solution to overcome mass transport and stability limitations, offering a significant advancement toward practical DMFC systems for compact and portable power devices.