Polytetrafluoroethylene-coated carbon nanotube sheet as superhydrophobic microporous layer for polymer electrolyte membrane fuel cells

초록

This study proposes a novel gas diffusion layer (GDL) for polymer electrolyte membrane fuel cells (PEMFCs), fabricated by spray-coating polytetrafluoroethylene (PTFE) onto purified carbon nanotube (CNT) sheets. The PTFE-coated CNT structure combines a highly conductive, nanoporous architecture with tunable hydrophobicity. Among PTFE loadings from 1 to 10 wt%, 2.5 wt% was identified as optimal, achieving a 46.9 % increase in peak power density compared to a commercial microporous layer (CMPL). The uniform PTFE coating enhanced water management without obstructing gas pathways or significantly increasing contact resistance. Durability testing confirmed comparable long-term stability to CMPLs, whereas uncoated CNT sheets failed within 6 h due to flooding. In addition to performance gains, the proposed GDL offers low-cost and scalable fabrication (similar to$30/kg). These results demonstrate that PCNT 2.5 wt% provides a balanced strategy for improving both performance and durability, offering a promising alternative to conventional MPLs in practical PEMFC applications.

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