Novel composite proton exchange membrane with long-range proton transfer channels constructed by synergistic effect between acid and base functionalized graphene oxide

Abstract

In this work, two different functionalized graphene oxide (GO), sulfonic acid functionalized GO (SGO) and amino functionalized GO (NGO), were synthesized and incorporated into the sulfonated poly(arylene ether nitrile) (SPEN) by single doping and codoping. It was found that the codoping of SGO and NGO contributed to the enhancement of proton exchange membrane performance. These two functionalized GO as fillers were uniformly dispersed in SPEN matrix and their synergistic effect created the long-range proton transfer channels along fillers/SPEN matrix interfaces. Meanwhile, acid-base pairs which was induced by strong interfacial interactions between fillers and SPEN matrix provided new and low-energy-barrier pathways for proton hopping, facilitating the proton conduction via Grotthuss mechanism. Among all the membranes, the codoped S/N-3 composite membrane exhibited the highest proton conductivity (0.064 S·cm−1 at 20 °C and 0.21 S·cm−1 at 80 °C). Besides, it was endowed with unprecedented dimensional stability, especially in high temperature (just 12.75% at 80 °C). Also, low methanol permeability was conferred owing to methanol trapping effect of two functionalized GO. Furthermore, S/N-3 composite membrane showed a superior selectivity of 4.48 × 105S⋅cm−3⋅s, which was nearly 10 times of that of commercialized Nafion 117. Our investigation provides a new strategy on the design of high performance composite membranes for applications of PEMs and other related fields.