Influence of Ink Composition on the Electrochemical Properties of Pt/C Electrocatalysts

Nanoparticle platinum on carbon black supports (Pt/high surface area carbon or Pt/HSC and Pt/Vulcan), widely used to benchmark novel electrocatalysts for proton exchange membrane fuel cells (PEMFCs), were characterized in rotating disk electrode (RDE) setups using multiple ink formulations. The oxygen reduction reaction (ORR) specific activity measured in 0.1 M HClO4 was higher by a factor of ~1.8 when Nafion ionomer was excluded from Pt/HSC inks/electrodes and substituted with trace amounts of a non-ionic surfactant for improved dispersiblity. Pt/Vulcan electrocatalysts did not exhibit this enhancement when Nafion was replaced with trace surfactant; however, eliminating both Nafion and the surfactant raised its specific and mass activity by a factor of ~1.8. The electrochemical areas for optimized inks/electrodes with and without Nafion were relatively unchanged at ~100 m2/g for Pt/HSC and ~65 m2/g for Pt/Vulcan. The higher measured activities have significant implications for established conventions regarding 'particle size effects'.