fig8

Figure 8. (A) Chronopotentiometric curve at a current density of 10 mA/cm² in 0.1 M KOH electrolyte of Co₃O₄ nanocrystal catalyst during in situ electrochemical TEM experiment. (B, C) HAADF-STEM images acquired at different reaction times [(B) 90 and (C) 145 s], showing the gradual generation of an amorphous matrix around the nanocrystals. (D) Superposition of (B) (red) and (C) (blue), showing the expansion of the sample area^[76]. HAADF-STEM: High-angle annular dark-field scanning transmission electron microscopy; TEM: transmission electron microscopy.