(Invited) Effects of Support Mesoporosity on Pt Dissolution in PEM Fuel Cells

Abstract

Interest in hydrogen as an energy carrier continues to grow due to the high demand for clean and sustainable, energy sources in the global energy market. Polymer exchange membrane fuel cells (PEMFCs) convert the chemical energy of hydrogen to electricity and have great potential as power sources for automotive applications. A key challenge in the development of cost-efficient and reliable PEMFC electrodes is catalyst layer durability. Typically, PEMFC cathodes comprise Pt-based electrocatalysts supported on high-surface-area carbons. It has been previously shown that the morphology and surface chemistry of carbon supports play significant roles in modulating both the activity and stability of Pt-based catalysts. Here, we will present our recent efforts to investigate the effects of the porous structures and surface properties of different mesoporous carbon powders on Pt dissolution in PEMFC cathodes. Using atomic layer deposition (ALD), we fabricate cathodes by depositing Pt nanoparticles of uniform sizes and mass loadings onto mesoporous carbon supports with varying pore sizes and surface areas. We then evaluate the beginning-of-life and end-of-life performance of these cathodes after accelerated Pt dissolution tests under single cell conditions, while comparing them to a microporous Ketjenblack-based cathode as a benchmark. Based on our findings, we discuss new insights into the underlying mechanisms for Pt dissolution within the porous structures of mesoporous carbon supports.