Fabrication of Function‐Graded Proton Exchange Membranes for Direct Methanol Fuel Cells Using Electron Beam‐Grafting

Abstract

Function‐graded proton exchange membranes (G‐PEMs) based on poly(tetrafluoroethylene‐co‐hexafluoropropylene) were fabricated for direct methanol fuel cells (DMFCs) via electron beam‐grafting using the heterogeneous energy deposition technique. The G‐PEMs had a water uptake gradient in the proton transfer direction, originating from the sulfonic acid group gradient. The distribution of sulfonic acid groups in the various G‐PEMs was evaluated using X‐ray photoelectron spectroscopy. Four types of PEMs (flat‐type, strong‐gradient, meso‐gradient, and weak‐gradient types) were fabricated. By varying the direction of the G‐PEMs, the methanol permeation test and DMFC operation were performed with two orientations of the sulfonic acid group gradient, decreasing from the methanol injection (anode) side (decrease‐type) or the other (cathode) side (increase‐type). The methanol permeability of the strong‐gradient, meso‐gradient, and weak‐gradient G‐PEMs was lower than that of Nafion®117 and the flat‐type PEM. The “increase‐type” orientation of the strong‐gradient G‐PEM resulted in the lowest methanol permeability. The DMFC performance of the G‐PEMs was influenced by the thickness direction, such as “decrease‐type” and “increase‐type.” The performance of the “decrease‐type” assembly was higher than that of the “increase‐type.” The “decrease‐type” assembly with P‐200 k (weak‐gradient G‐PEM) exhibited the highest performance of the fabricated PEMs, comparable to that of Nafion®117.

Novel bilayer well-aligned Nafion/graphene oxide composite membranes prepared using spin coating method for direct liquid fuel cells

“…Several approaches, such as pore-filling techniques [13,14,15], electron beam grafting [16], and electrospun nanofiber film [17] have recently been proposed to decrease the fuel cross-over phenomenon through electrolyte membranes. Graphene oxide (GO) has attracted attention due to its unique amphiphile [18] and high aspect ratio properties [19].…”

Synergistic electrocatalytic activity of a spinel ZnCo2O4/reduced graphene oxide hybrid towards oxygen reduction reaction

“…Many alternatives in the area of energy storage such as supercapacitors, lithium-ion batteries, metal-air batteries, etc. and also in the area of energy conversion like fuel cells and solar cells have gone under intense investigation in recent years [1][2][3][4][5]. Among all the available energy conversion options, fuel cells appear to be more promising because of their ability to convert chemical energy into electrical energy in an efficient and non-polluting way [6].…”