Skip to main content
eScholarship
Open Access Publications from the University of California

Exploring Proton Activity at the Membrane/Electrode Interface with Microelectrodes

Abstract

Microelectrode measurements using a polycrystalline platinum microelectrode were used to simulate the membrane/electrode interface of a membrane-electrode-assembly (MEA) architecture. The proton activity for the hydrogen-evolution reaction (HER) was evaluated for 40, 60, and 80% relative humidity. Proton activity was calculated to be 0.5, 1.0 and 2.0 for 40, 60, and 80% relative humidity, respectively, using open circuit potential measurements between Nafion 211 and 1 molal HClO4. The fraction of protons which dissociate at a given relative humidity condition appears to be a distinctive factor in proton activity for Nafion 211 compared to an aqueous electrolyte. The microelectrode measurements exhibited a Tafel slope of ~120 mV/dec, similar to that observed for platinum in MEA systems, demonstrating that kinetic measurements made with microelectrodes can be representative of MEA kinetics.

Main Content
For improved accessibility of PDF content, download the file to your device.