Characterization of Teflon-like carbon cloth prepared by plasma surface modification for use as gas diffusion backing in membrane electrode assembly

The hydrophobic property of carbon cloth was largely improved by plasma treatment and the Teflon-like property was effectively applied to fabricate a gas diffusion backing (GDB) for use in membrane electrode assembly (MEA). The surface morphology, hydrophilic/hydrophobic property and electron conductivity of the as-prepared GDB was fully characterized. The water contact angle and SEM microstructure image of the CF4, CHF3 plasma-treated GDB were both indicated as ∼130°, and very few gas diffusion pores either sealed or blocked by excessive hydrophobic material residual. The measured resistivity values of CF4 plasma, CHF3 plasma, SF6 plasma and commercial carbon were 0.45, 0.5, 0.47 and 0.49, respectively, which indicates that the electrical resistivity of carbon cloth with CF4 plasma treatment was slightly lower than others. In cell performance test, the CF4 plasma-treated modules could also produce better property than those MEAs prepared with CHF3 plasma-treated GDB, SF6 plasma-treated GDB and commercially available GDB, leading to the highest fuel cell performance with an optimal power output of 350 mW cm−2.