Electron beam patterned Nafion membranes for DMFC applications

Patterned Nafion 212 membrane prepared by electron beam lithography (EBL) coupled with dry etching was tested for DMFC applications. Pristine, O2 blanket-etched, and electron beam exposed Nafion 212 test cells were also prepared and compared. Several parameters including in-plane conductivity, methanol crossover, I–V characteristics, and through-plane ohmic resistance were evaluated. The patterned membrane had the best combination of properties, benefiting from the exposure to electron beam and interfacial area enlargement as evidenced by its superior power density. The maximum power densities were 29.3, 32.5, 48.2, and 63.1 mW cm−2 for the pristine, exposed, O2 blanket-etched, and patterned membrane respectively. A Nafion 117 membrane test cell was also compared. While it exhibited reduced methanol crossover, it also had higher ohmic resistance and Tafel slope. The patterned Nafion 212 provided a 25% increase in power density compared to the N117 membrane.

► Performance evaluation of EBL and dry etching patterned Nafion 212 membranes. ► Comparison to pristine, electron beam exposed, and O2 plasma treated Nafion. ► Chemical modification and interfacial enlargement improve performance. ► Significantly improved performance results for patterned DMFC. ► Comparison of patterned N212 and pristine N117 DMFCs.