Improved hydroxide conductivity and performance of nanocomposite membrane derived on quaternized polymers incorporated by titanium dioxide modified graphitic carbon nitride for fuel cells

A series of quaternary aminated poly(arylene ether sulfone) (QPAES) nanocomposite membranes (QPAES-TiO2/g-C3N4) were fabricated by a double-component nanocomposite system of titanium dioxide/graphitic carbon nitride (TiO2/g-C3N4) and the polymer. TiO2 nanoparticles were firstly functionalized with the highly ion-conductive groups of g-C3N4 to synthesize TiO2/g-C3N4 nanocomposites. Their fundamental properties including water absorbing-swelling behavior, thermo-mechanical property, chemical stability, ion conductivity and fuel cell performance were investigated. The QPAES-TiO2/g-C3N4 membrane containing 0.45 wt% TiO2/g-C3N4 revealed considerable enhancements in ion conductivity, chemical stability and fuel cell performance. It absorbed water as high as 88.7% but expanded less than 13% in the membrane in-plane direction, and showed hydroxide conductivity of 43.8 mS/cm at 80 degrees C, besides, in a H-2/O-2 fuel cell, its maximum power density arrived at 64.3 mW/cm(2) under a current density of 131.2 mA/cm(2) at 80 degrees C. This work demonstrated that membrane with the proper content of TiO2/g-C3N4 nanocomposites could be a promising candidate for fuel cell applications. (C) 2020 Elsevier Ltd. All rights reserved.