Highly Effective Proton-Conduction Matrix-Mixed Membrane Derived from an -SOH Functionalized Polyamide.

Developing a low-cost and effective proton-conductive electrolyte to meet the requirements of the large-scale manufacturing of proton exchange membrane (PEM) fuel cells is of great significance in progressing towards the upcoming "hydrogen economy" society. Herein, utilizing the one-pot acylation polymeric combination of acyl chloride and amine precursors, a polyamide with in-built -SOH moieties () was facilely synthesized. Characterization shows that it possesses a porous feature and a high stability at the practical operating conditions of PEM fuel cells. Investigations of electrochemical impedance spectroscopy (EIS) measurements revealed that the fabricated displays a proton conductivity of up to 8.85 × 10 S·cm at 353 K under 98% relative humidity (RH), which is more than two orders of magnitude higher than that of its -SOH-free analogue, (6.30 × 10 S·cm), under the same conditions. Therefore, matrix-mixed membranes were fabricated by mixing with polyacrylonitrile (PAN) in different ratios, and the EIS analyses revealed that its proton conductivity can reach up to 4.90 × 10 S·cm at 353 K and a 98% relative humidity (RH) when the weight ratio of :PAN is 3:1 (labeled as ), the value of which is even comparable with those of commercial-available electrolytes being used in PEM fuel cells. Additionally, continuous tests showed that possesses a long-life reusability. This work demonstrates, using the simple acylation reaction with the sulfonated module as precursor, that low-cost and highly effective proton-conductive electrolytes for PEM fuel cells can be facilely achieved.