Proton availability governs the high-current oxygen reduction reaction in a gas diffusion electrode

Gas diffusion electrodes enable oxygen reduction reaction studies at current densities beyond the limits of rotating disk electrodes, yet the role of electrolyte proton availability remains unclear. Herein, oxygen reduction polarization curve behavior was investigated using 0.1–2 M HClO 4 . While cyclic voltammetry and electrochemical surface area were consistent, current plateaus emerged at low acid concentrations. These results show that proton transport can limit the achievable current density. Achieving current densities of 1 A cm −2 required at least 0.8 M HClO 4 , while 2 M HClO 4 was necessary to reach 2 A cm −2 . These findings provide practical guidance for electrolyte selection in high-current gas diffusion electrode measurements and demonstrate that they can serve as a platform for studying proton transport behavior.