Zoom in Catalyst/Ionomer Interface in Polymer Electrolyte Membrane Fuel Cell Electrodes: Impact of Catalyst/Ionomer Dispersion Media/Solvent

Abstract

Large-scale applications of polymer electrolyte membrane fuel cells (PEMFCs), are throttled primarily by high initial cost and durability issues of the electrodes, which essentially consist of the nanoparticulate catalysts (e. g. Pt) having accessibility to electrons (e-), protons (H +) and fuel/oxidant through catalyst support, polymer electrolyte ionomer and porous gas diffusion layer, respectively. Hence, to achieve high electrode performance in terms of activity and/or durability, understanding and optimization of the catalyst/support and catalyst/ionomer interfaces is of significant importance. Present study demonstrates an alternative route to inspect the catalyst/ionomer interface through accelerated stress test (AST) combined with electrochemical impedance spectroscopy (EIS). Various interface is created through catalyst inks prepared using commercial Pt/C catalyst powder dispersed in different solvents. Electrode degradation pattern turns out to be a very useful tool to interpret catalyst/ionomer interface structure. Variations of interfacial impedance, electrochemical surface area (ECSA) and double layer capacitance (DLC) with the number of potential cycles suggested significant impact of catalyst/ionomer interface on the catalyst performance. A quantification of the degradation mechanisms responsible for ECSA loss during AST was employed to further understand the correlations between the electrochemical

Pt/C Electrocatalyst Synthesis from Recycling of the Spent PEMFC Membrane Electrode Assembly: A Closed Loop Circular Economy

“…The Pt nanoparticles grow significantly during AST to an average particle of 5.5 nm as compared to that of 2.6 nm for the pristine Pt/C-MEA-CC sample. Similar growth of Pt nanoparticles has been observed previously 33 for the commercial Pt/C electrocatalysts as well. However, we would like to point out that such particle growth phenomenon is a dominant and artificially amplified degradation mechanism for catalyst AST evaluation in aqueous electrolyte, which is significantly reduced in solid electrolyte environment.…”

Highly efficient oxygen evolution reaction via facile bubble transport realized by three-dimensionally stack-printed catalysts

“…For this purpose, inter-catalyst space should secure the maximized utilization efficiency of the surface area, which is not easy to accomplish with Ir black nanoparticles (one of the state-of-the-art OER catalysts). Furthermore, ionomers, which are typically mixed with Ir nanoparticles for enhancing ionic conductivity in OER electrodes, may reduce the direct contact between the catalytic surface and reactants and also interfere with efficient transport of the generated gas 23 .…”

Sustainable Platinum Recycling through Electrochemical Dissolution of Platinum Nanoparticles from Fuel Cell Electrodes

“…The catalyst/ionomer interface has been reported to affect the electrochemical catalytic performance of the electrode significantly . The catalyst/ionomer interface may similarly affect the Pt/electrolyte interaction, and hence the Pt‐dissolution during the electrochemical treatment. To study the impact of catalyst/ionomer interface on the Pt‐dissolution, PEMFC electrodes having different catalyst ink compositions with Nafion contents of 0, 15, 30 and 45 wt.% were studied.…”