fig3

Figure 3. IL-SEM images of PtCo/C sample (A) before and (B) after potential cycling. The white circles indicate that some particles are dissolved. IL-STEM images of PtCo/C sample (C) before and (D) after potential cycling. The green arrows and orange dashed circles indicate particle detachment, white dashed circles indicate particle coalescence and blue arrows indicate particle shrinkage and reshaping. High-resolution IL-STEM images of PtCo sample (E) before and (F) after the potential cycling. (G) Atomic columns with phase detection before (top panel) and after (bottom panel) potential cycling. (H) Overlay of atomic columns before and after the reaction, showing the changes of surface atoms^[56]. IL-SEM: Identical location scanning electron microscopy; STEM: scanning transmission electron microscopy.