Fig. 5: Pourbaix diagrams of real-scale (several nanometer-size) Pt NPs.
a Pourbaix diagram of Pt561 (Coh). b Pourbaix diagram of Pt3871 (Coh). c Pourbaix diagram of Pt6525 (Coh), which corresponds to ~4.8 nm in diameter. The white, blue, orange, and red shaded area represent bare Pt NPs, OH-covered, O-covered, and Pt dissolution phases, respectively. As the color became darker, more adsorbates are adsorbed. The red and gray spheres of the inset atomic model represent oxygen and platinum atoms, respectively. d Difference in the adsorption energies between the fully O-covered phase (Pt-(O)1ML) and fully OH-covered phase (Pt-(OH)1ML) as a function of NP size. Eads represents the adsorption energy per adsorbate. The 2nd y axis shows the ratio of the number of vertex and edge atoms to the number of terrace atoms as a function of NP size.
