Remarkable solid-state proton conduction in sulfur- and nitrogen-functionalized few-layer graphene

Sulfur- and nitrogen-functionalized few-layer graphene exhibited remarkable proton conductivity of 0.0865 Scm-1 at 95 °C, 95% RH, comparable to Nafion, with a low activation barrier and exceptional stability over a month. The incorporation of sulfonic acid and nitrogen-functionalities resulted in acid-base synergism and excess charge carrier for proton conduction.