Be aware of the effect of electrode activation and morphology on its performance in gas diffusion electrode setups

The superior performance enhancement in catalyst research for proton exchange membrane fuel cells (PEMFC) revealed in the model rotating disc electrode (RDE) environment is rarely demonstrated in membrane electrode assemblies (MEA). The discrepancy is typically attributed to the difference in the chemical structure and morphology of the catalyst layer (CL), affecting the transport of reactants of the oxygen reduction reaction (ORR). In this study, the gas diffusion electrode (GDE) half-cell setup is used to focus on crucial aspects of CL development, especially on the activation and morphology of CLs, to gain a fundamental understanding of the development of PEMFCs. Adjusting the CL porosity by using different solvent compositions of water and isopropyl alcohol and implementing an activation method for low platinum content catalysts, we focus on understanding the contributions of macro-porosity and hydrophobicity in a liquid electrolyte-based system. We show that macro-porosity significantly influences the O 2 mass transport in the CL, demonstrating increased performance with higher porosities. Coupling inductively coupled plasma mass spectrometry (ICP-MS) with the GDE half-cell setup, we propose a method for qualitative estimation of water content in the CL. Lower macro-porosity shows higher platinum dissolution, attributed to improved mass transport of dissolved ions in aqueous media. • High reliability of GDE setup via activation and catalyst layer morphology control. • Adjusting the catalyst layer porosity by tuning water and IPA in the ink. • Macro-porosity significantly influences the O 2 mass transport. • GDE-ICP-MS for a qualitative estimation of water content in a catalyst layer. • Mass transport of dissolved Pt species controls the overall Pt dissolution.