Effect of Ionomer/Carbon Ratio and Catalytic Layer Thickness on the Operation of PEM Single Cells

Abstract

The electrochemical operation of membrane electrode assemblies (MEAs) with different Nafion/C composition (0%, 20%, 30%, 40%, and 50%) and the same ultralow platinum load (0.02 mg_Pt cm⁻²) has been investigated. The electrodes were manufactured by depositing the catalytic ink, prepared with catalyst HiSPEC9100, onto the gas diffusion layers by wet powder spraying. MEA with 30% Nafion/C reached the highest power density (675 mW cm⁻²) and the lowest mass of Pt per power (0.059 g_Pt kW⁻¹) under H₂/O₂ 2 bar gauge pressure, the last quotient being 1.7 time less than USDRIVE objective for 2025. The electrochemical functioning of current membrane-electrode setups is compared with an analogous series with thicker electrode catalytic layer prepared with a commercial catalyst with a lower percent of Pt/C. Scanning electron microscopy characterization analysis of catalytic layers prepared by wet spraying exhibited an ionomer homogeneous network.