Figure 1: HAADF-STEM images and histogram of size distributions.

(a) 0.08%Pt/FeOx-R200. Scale bar, 1 nm. (b) 0.08%Pt/FeOx-R250. Scale bar, 2 nm. (c) 0.31%Pt/FeOx-R250. Scale bar, 2 nm. (d) 0.75%Pt/FeOx-R250. Scale bar, 2 nm. (e) 4.30%Pt/FeOx-R250. Scale bar, 10 nm. (f) Histogram of size distributions. The circles, squares and triangles in the figures represent the single atoms, 2D rafts and 3D clusters/particles, respectively.