A novel screening tool for gas diffusion electrodes through hanging electrode configuration: Impact of Nafion fraction on the ORR activity

Abstract

To achieve high current density of oxygen reduction reaction (ORR) and mimic the realistic working conditions of the fuel cell, a simple hanging electrode experimental set-up for the gas diffusion electrode (GDE) test is developed. The ORR activities of GDE with 15, 30, and 45 wt% Nafion content were accessed in an oxygen environment hanging electrode set-up. The GDE containing 15 and 30 wt% Nafion demonstrated relatively high ORR activity, while the GDE with 45 wt% Nafion exhibited the lowest ORR activity. Further, the mass-transport properties were accessed through electrochemical impedance spectroscopy (EIS) measurement, which revealed that GDE with 45 wt% Nafion offers the highest equivalent distributed resistance (EDR) and polarization resistance (R_P); therefore, the lowest ORR activity. The Advantages of the ORR activity measurements in hanging electrode configuration over the conventional thin-film rotating disk electrode (TF-RDE) method are also highlighted. Based on ORR activity measurements and impedance analysis in newly developed hanging electrode setup, GDE with 30 wt% Nafion content is recommended for fuel cell MEA construction using state-of-the-art catalyst (Pt/C ∼ 60 wt%) structure. The hanging electrode set-up can provide a quick firsthand screening on the ORR activity of GDEs and predict the GDE behaviour in the fuel cells.