A General Approach to the Synthesis of M@Au/Ag (M = Au, Pd, and Pt) Nanorattles with Ultrathin Shells Less Than 2.5 nm Thick

This article reports a general approach to the facile synthesis of M@Au/Ag (M = Au, Pd, and Pt) nanorattles. The synthesis involves three major steps: (i) formation of M@Ag nanocubes via seed‐mediated growth, (ii) conformal deposition of ultrathin Au shells on the M@Ag nanocubes by reducing HAuCl 4 with ascorbic acid under an alkaline condition, and (iii) formation of M@Au/Ag nanorattles through a galvanic replacement reaction between the Ag shells and aqueous HAuCl 4 . The deposition of an ultrathin Au shell prior to the galvanic replacement reaction is crucial to a successful synthesis as this shell can enhance the mechanical strength of the resultant nanorattles by preventing the Au/Ag alloy shell from fragmentation during the galvanic replacement process. The localized surface plasmon resonance peak of the nanorattles is determined by the thickness of the Au/Ag alloy shell. For Au@Au/Ag nanorattles with an edge length of 15 nm, they could be tuned to have near‐infrared absorption and excellent photothermal conversion capability for their use as transducers in the effective destruction of cancer cells through laser irradiation.