Improvement of Catalyst Layers in Direct Methanol Fuel Cells Using Dual-Electrode Carbon Nanotube Carrier Structure

The sole use of carbon nanotubes (CNTs) as single-electrode carriers in direct methanol fuel cells (DMFCs) creates structural disparities that increase resistance, impair catalyst utilization, and limit discharge duration. This study presents a novel dual-electrode CNT-based carrier structure designed to enhance mass transport and electron conduction, thereby improving DMFC power output and durability. The CNTs were grown in situ via nitrogen sintering onto the microporous layer, with parameters optimized to enhance surface morphology and conductivity. The impact of this dual-electrode CNT carrier was evaluated through microstructural characterization, cyclic voltammetry, electrochemical performance testing, and service life assessment. Results demonstrate that the structure improves catalyst dispersion, electrochemical active surface area (ECSA), and charge transfer efficiency, while reducing ohmic resistance and charge transfer impedance. Compared to traditional carbon black (CB) carriers, peak power increased by 51.06%. Under China Light Vehicle Test Cycle (CLTC) conditions, discharge duration increased by a factor of 1.7, indicating higher energy efficiency. These improvements are attributed to the dual-electrode architecture’s synergistic enhancement of proton transport, balanced electrochemical kinetics, and reduced interfacial resistance.