Fig. 4: Characterizations of the synthesized bimetallic NPs.

XRDs for a Au51Pd49, b Ni61Pt39, c Pd50Cu50, d Pd52Ni48, e Pt58Co42, f Pt52Pd48, g Rh56Ni44, h Rh56Pt44 NP samples. For comparison, the red and green lines in the XRD patterns correspond to the peaks of pure elements in each bimetallic NP. The blue peaks were simulated with the crystal structures of the bimetallic system predicted by DFT calculations. Above each XRD pattern, the element mapping images acquired by STEM-EDX are included, where the first image (the most left) is the overlay image of the maps for elements in each bimetallic NP. The scale bars correspond to 20 nm. The enlarged images of the STEM-EDX are also provided in Supplementary Figures 2~9.