Characterization of Catalyst Inks By Rheology and Microscopic Particle Properties

Abstract

Both rheological measurement and zeta potential measurement of catalyst inks used for catalyst layers of proton exchange membrane fuel cells were conducted and characterized the catalyst inks. The state of the catalyst ink affects dynamics of materials during the fabrication process of the catalyst layers, and then the resultant structure. Therefore, quantitative evaluation of the catalyst ink is required. In this study, ionomer dispersion, pseudo-catalyst ink and catalyst ink with various ionomer content were evaluated to clarify the relationship between the rheological behavior and the types and amount of particles and interparticle interactions in the slurry. Ionomer works as a dispersant like a surfactant. Adding ionomer changed the rheological behavior from non-Newtonian to Newtonian, and hysteresis was suppressed. Ionomer adsorption ratio was affected by the existence of platinum particles on carbon particles. As the result, the rheological behavior of the pseudo-catalyst ink and catalyst ink with the variation of ionomer content was different.