Fig. 2. Low-magnification TEM image (a) of OM-YS Au@AgPd NPs. HRTEM image (b) of the selected area of one individual OM-YS Au@AgPd NP (the inset in (a)). TEM images of an OM-YS Au@AgPd NP taken at different tilting angles from 0 (c) to –20° (d) with respect to the rotation axis. OM-YS Au@AgPd NPs are derived from CS NPs with 30 nm Au NPs and 5.4 nm thick Ag shells via galvanic reactions at room temperature. The Pd²⁺ to Ag molar ratio is 0.5 and the citrate concentration is 0.03 wt%.