Synergistic Effects of CNF-TiO2 Composites and Process Parameters on DMFC Performance Enhancement

Abstract

Direct methanol fuel cells (DMFCs) face challenges from methanol crossover and performance degradation caused by inefficient microporous layer (MPL) designs, where conventional carbon-based MPLs show limitations in surface coverage uniformity, catalyst utilization efficiency, and pore structure balance. To address these issues, this study developed an optimized MPL using carbon nanofiber-titanium dioxide (CNF-TiO2) composites through parametric optimization of the fabrication process. Key variables included MPL loading density, CNF:TiO2 mass ratio, Nafion binder concentration, and methanol feed concentration, which were analyzed via screening experiments and Response Surface Methodology (RSM) using a Central Composite Design (CCD). The optimization targeted three response metrics: power density (R1), open-circuit voltage (R2), and peak current density (R3). The results demonstrated that the modified CNF-TiO2 microporous layer (MPL) exhibited a synergistic effect when optimized with the selected parameters. Initial screening experiments examined MPL loading, CNF-to-TiO2 ratio, Nafion® content, and methanol concentration, revealing that the composition ratio, Nafion® content, and methanol concentration had significant impacts on the cell's performance responses. These key parameters were further explored using Response Surface Methodology (RSM). The optimized MPL exhibited improved..see more.