Giant proton transmembrane transport through sulfophenylated graphene in a direct methanol fuel cell

TL;DR

This study demonstrates that chemically functionalized graphene with sulfophenyl groups can serve as an effective proton-conducting membrane in fuel cells, achieving significantly higher conductance and power density than traditional materials.

Contribution

The paper introduces a novel chemical functionalization of graphene that creates hydrophilic ion pathways, enabling high proton conductivity and improved fuel cell performance.

Findings

Transmembrane conductance up to ~50 S/cm2, 5000 times higher than pristine graphene.

Power density of 1.6 W/mg in a direct methanol fuel cell, twice that of Nafion 117.

Creation of hydrophilic ion paths through functionalized graphene.

Abstract

An ideal proton exchange membrane should only permeate protons and be leak tight for fuels. Graphene is impermeable to water and poorly conducting to protons. Here, we chemically functionalized monolayer graphene to install sulfophenylated sp3 dislocations by diazotization. Selective to protons, transmembrane areal conductances are up to ~50 S/cm2, which is ~5000 fold higher than in pristine graphene. Mounted in a direct methanol fuel cell, sulfophenylated graphene resulted in power densities up to 1.6 W/mg or 123 mW/cm under standard cell operation (60 C), a value ~two-fold larger than micron-thick films of Nafion 117. The combination of sp3 dislocations and polar groups, therefore, allow the creation of hydrophilic ion paths through graphene and unveils a novel route to rationalize transmembrane hydron transport through 2D materials.