Enhancing performance and chemical stability of Nafion composite proton exchange membranes by the impregnation of phosphotungstic acid functionized CeO2

CeO 2 is incapable of conducting protons and tends to leach from the proton exchange membrane (PEM) under the acidic conditions during fuel cell operation, consequently deteriorating both the power density and durability of the fuel cell. In this work, we prepared an acid-insoluble HPCe hybrid by combining polyethyleneimine-polydopamine (PEI-PDA) crosslinked coated CeO 2 with phosphotungstic acid, a strong proton conductor. The PEI-PDA coating not only prevents the dissolution of CeO 2 in acidic environments but also suppresses the leaching of HPW. When incorporated into Nafion, the composite membrane containing 2 wt% HPCe exhibits a proton conductivity of 0.115 S cm −1 in liquid water, which is 15% higher than that of the recast Nafion membrane (0.100 S cm −1 ), while remaining stable for 2 months. After being assembled in the fuel cell, the performance and operation stability of the composite membrane significantly outperforms the recast Nafion membrane.