Promoting Membrane Electrode Assembly via Blocking Nafion's Sulfonate Group with Cyclohexanol: Releasing Pt Activity and Improving Mass Transport

Abstract Owing to the physical confinement of Nafion ionomer and the specific adsorption of sulfonate (-SO3H) group on Pt, the catalytic activity of Pt-based catalysts for the oxygen reduction reaction (ORR) has been badly suppressed in membrane electrode assembly (MEA). Herein, we report a blocking strategy with cyclohexanol to mitigate the detrimental impacts of Nafion ionomer in cathode catalyst layer. The stereoscopic cyclohexanol incorporated in the ionomer has cut off the poisoning adsorption of -SO3H group on Pt and increased the loose of the ionomer in catalyst layer. As a result, MEA with cyclohexanol has reached a mass activity as high as 0.87 A mgPt-1 @0.85 V and a peak power density of 1.772 W cm-2 in the H2/O2 fuel cell, 40% and 47% higher relative to these of the MEA with only Nafion ionomer, respectively. The demonstrated strategy provides a new direction for fully releasing the catalytic activity of Pt in MEA.