Published a paper on electrophoresis of carbon black suspensions.
Platinum-supported carbon black CB is often used in catalytic inks for fuel cells. These particles have a primary structure with a size of several tens of nanometers, but they rarely exist as single particles and often contain secondary or tertiary aggregates. The formation of agglomerates is a common issue in maintaining fuel cell performance, and ionomers such as Nafion are commonly added to improve the dispersion state. However, such inks are made of “platinum” and “carbon black,” which are completely opaque to light, in addition to organic polymers and ionomers as dispersing agents, making their analysis extremely difficult with conventional methods.
Illustration by Mao Yamada
We are the leading laboratory in the world to have invented dynamic ultrasonic technology.
This time, we conducted research to investigate the dynamics of electrophoretic carbon black particles in real time. Since ionomers carry an electric charge, if they are well coated with CB, we should be able to visualize their motion in response to an electric field. Our previous study described how to analyze electrophoretic sound scattering (ESS) on particles a few microns in size, and now we present a new application to CB particles at the nano to submicron level.
Illustration by Mao Yamada
Of course, in addition to the ESS method, which analyzes the particle surface, the dynamic ultrasound scattering (DSS) method, which can evaluate the size distribution of nanoparticles without dilution, and the ultrasound spectroscopy (US) method, which can evaluate the stiffness and viscosity of particles, can be applied simultaneously, so the information obtained is enormous even with a single ultrasound method. In this study, in particular, we have also shown that it is possible to quantify the thickness and amount of the ionomer layer coating the particles while obtaining information on the hydrophilicity/hydrophobicity of the particle surface.