Optical properties of Pd-Ag and Pt-Ag nanoboxes synthesized via galvanic replacement reactions
Silver nanocubes dispersed in water were transformed into Pd-Ag or Pt-Ag nanoboxes by adding either Na 2PdCl 4 or Na 2PtCl 4. By controlling the amount of noble metal salt added, and therefore the molar ratio of Na 2PdCl 4 or Na 2PtCl 4 to Ag, we could tune the surface plasmon resonance peak of the nanostructures across the entire visible spectrum, from 440 to 730 nm. Replacement of Ag with Pd resulted in the formation of a nanobox composed of a Pd-Ag alloy single crystal, but the nanobox formed after replacement of Ag with Pt was instead composed of distinct Pt nanoparticles. DDA calculations suggest that both nanoboxes absorb light strongly, with Q abs/Q sca ≈ 5. After galvanic replacement, Pd-Ag and Pt-Ag nanostructures remain SERS active, suggesting their use as a SERS probe for studying the dependence of interfacial chemistry on composition. © 2005 American Chemical Society.
Chen, J; Wiley, B; McLellan, J; Xiong, Y; Li, Z-Y; Xia, Y
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