Chemistry and microstructure of C-supported Ru catalyst nanoparticles: A correlative study

Ru@Pt core shell nanoparticles possess optimal catalytic properties that facilitate the anodic oxidation reaction of H₂ with decreased Pt loading in hydrogen fuel cells. Moreover, since they preferentially oxidize CO, Pt poisoning is considerably reduced, which significantly improves the stability of the cell. The Ru cores used in this system are usually synthesized by dissolving a RuCl₃*H₂O precursor in an ethylene glycol-carbon black-NaOH mixture. However, the possibility that remnant Cl and Na from the synthesis process are present in the Ru nanoparticles has not been extensively studied. Therefore, due to the challenges in detecting impurities with traditional characterization methods, here correlative atom probe tomography (APT) with scanning transmission electron microscopy ((S)TEM) techniques were implemented. The capabilities of APT to obtain chemical information with high sensitivity at the nanoscale, in combination with the high spatial resolving power of (S)TEM, provide the necessary resolution to fully characterize the structure and chemical makeup of Ru nanoparticles.