Effect of carbon nanotube-based catalyst layer surface roughness on polymer electrolyte membrane fuel cell performance

Abstract

Polymer Electrolyte Membrane Fuel Cells (PEMFCs) play a centralized role in the decarbonization of energy systems due to their carbon-free electricity generation. However, low utilization efficiency of the Pt electrocatalyst has hindered the widespread adoption of PEMFCs. Herein, the effect of surface roughness on a catalyst layer (CL) based on carbon nanotubes (CNTs) in contact with polymer electrolyte membranes (PEMs) in PEMFCs was studied to examine the relationship between such surface roughness and Pt utilization efficiency. The surface roughness of the vacuum-filtered CL sheets was evaluated using a laser microscope. The surface of the CL sheet contacting the filter membrane was smoother than that of the surface exposed to air. When the CL sheet with the smoother surface was laminated with the PEM to fabricate a membrane electrode assembly (MEA), the power density of the single cell was 604.6 mW cm⁻² at 80 °C under 100% relative humidity (RH), which was greater than that of the MEA with a rougher CL surface (542.4 mW cm⁻²).