This study describes a simple but effective route of sulfonation of mesoporous carbon by anchoring sulfonic acid-containing aryl radicals and their subsequent impregnation to a perfluorosulphonic acid ionomer to form a hybrid membrane.

Sulfonic acid-functionalized mesoporous carbon (sMC) is explored as a potential hydrophilic inorganic filler to realize a hybrid membrane with Nafion for polymer electrolyte fuel cell (PEFC) applications under reduced relative humidity (RH).

Due to the high density of –SO₃H groups on mesoporous carbon, the ion exchange capacity and proton conductivity of the hybrid membrane significantly increases.

Combination of high surface area with strong-acid functionality of sMC, the hybrid membrane ameliorates the PEFC performance at low RH values in relation to PEFCs employing a pristine Nafion membrane. Proton conductivity of the Nafion–sMC (0.25 wt%) hybrid membrane at 20% RH is 7.9×10⁻² S cm⁻¹, which is 2.5 order of magnitude higher than that of a pristine recast Nafion membrane.