fig7

Figure 7. In situ HAADF-STEM images of PtNi alloy nanoparticle catalyst captured during in situ electrochemical liquid cell test. (A) Potential profile used in in situ experiment. The marked points correspond to the images shown below with the same labels. (B-I) Images acquired during in situ experiment under specific conditions, as marked in the potential profile. The orange circles indicate the motion and growth of nanoparticles, yellow arrows indicate atom redeposition and the green arrow in the cutouts shows the coalescence of two nanoparticles. The fields of view of the left and right cutouts are 50 and 44 nm, respectively^[73]. HAADF-STEM: High-angle annular dark-field scanning transmission electron microscopy.