Fig. 1: Morphology characterizations of the Ir1/(Co,Fe)-OH/MI sample.

a, TEM micrograph with a corresponding SAED image. b, Integrated TEM and HR-TEM images. c, AFM characterization. d,e, HAADF-STEM images. Holes (d). Ir single atoms (e). f, TEM image with corresponding elemental maps. g, High-resolution elemental map. h, Three-dimensional atom-overlapping intensity value representation. i, Intensity profile along the dashed rectangle in e. Note: M in i represents either Co or Fe.