Freeze‐Thawed Nafion‐Poly(vinyl alcohol) Self‐healing Membranes for Direct Methanol Fuel Cells

Self‐healing proton‐exchange membranes (PEMs) made of poly(vinyl alcohol) (PVA) and Nafion were synthesized using the freeze‐thaw method. Since PVA is more selective towards water than methanol, the blend membrane successfully reduced methanol permeability and improved selectivity compared to the recast Nafion membrane. The addition of PVA also helped the membrane self‐heal by promoting the formation of hydrogen bonds. In contrast to the pristine Nafion, which exhibited even more severe methanol crossover after being damaged than before, the Nafion‐PVA membrane underwent a self‐healing process and regained much of its methanol barrier function. These advantageous characteristics of the Nafion‐PVA membrane suggest its potential use in direct methanol fuel cells (DMFCs).