Uncovering Nafion-multiwalled carbon nanotube hybrid membrane for prospective polymer electrolyte membrane fuel cell under low humidity

Abstract

Sulfonic acid functionalized multiwalled carbon nanotube (sMWCNT) is explored as a potential inorganic filler as well as a solid acid proton conducting medium to realize a hybrid membrane with Nafion for a polymer electrolyte membrane fuel cell (PEMFC) for low humidity applications. The simple, but effective, functionalization of MWCNT is performed by sulfonic acid containing aryl radicals to increase the number of sulfonate groups per unit volume of MWCNT domain. The hybrid membrane made from such fillers has a positive impact on the proton conduction and water diffusion, especially under the low relative humidity (RH) conditions. A PEMFC with a Nafion-sMWCNT (0.25 wt%) hybrid membrane delivers a peak power density of 549 mW cm−2 at a load current density of 1.7 A cm−2 while operating at 20% RH, 60 °C under ambient pressure. By contrast, operating under identical conditions, a peak power density of only 67 mW cm−2 at a load current density of 0.2 A cm−2 is obtained with the pristine recast Nafion membrane.