Amine functionalized carbon nanotube (ACNT) filled in sulfonated poly(ether ether ketone) membrane: Effects of ACNT in improving polymer electrolyte fuel cell performance under reduced relative humidity

Amine functionalized carbon nanotube (ANCT) is applied as an inorganic potential proton conducting material embedded in a sulfonated poly(ether ether ketone) (SPEEK) matrix. The morphological, structural, thermomechanical, physiochemical and electrochemical properties of SPEEK/ACNT composite were investigated and compared to obtained results from bare SPEEK. The synthesized ACNT-incorporated SPEEK membrane have uniform and dense morphology and exhibit improved properties as proton exchange membrane (PEM); for example, SPEEK/ACNT possessed higher thermal stability and tensile strength than SPEEK alone. The amine functionalized structure of ACNT is assumed to be one of critical factors resulting in higher performance of SPEEK/ACNT membrane, since it can induce acid-base conducting networks between ACNT and SPEEK matrix, which would improve water uptake and proton conductivity while lowering ion exchange capacity of membrane. When used in 20% relative humidity, a polymer electrolyte fuel cell (PEFC) with SPEEK/ACNT membrane is found to exhibit much higher performance than a PEFC with bare SPEEK, suggesting the potential use of SPEEK/ACNT membrane as PEM.