fig9

Figure 9. (A) In situ LC-TEM images showing the evolution of oxygen nanobubble (blue arrows) and surface layer (red arrows) with OER time. The scale bar represents 20 nm. (B) Corresponding evolution profiles of the surface layer thickness (red) and nanobubble volume (blue). The nanobubble volume is calculated from the boundary curvature. Error bars are ± 0.25 nm for the surface layer thickness and ± 1 × 10⁴ nm for the nanobubble volume^[77]. LC-TEM: Liquid cell transmission electron microscopy; OER: oxygen evolution reaction.