Pt-guided formation of Au nanoislands on Au nanorods and its optical properties

Core–shell nanostructures exhibit unique optical and catalytic properties that are dependent on their morphology and composition. In this paper, a general and facile way was developed to prepare Au-nanoisland-coated Au nanorods with porous structures. Pt nanodots were first formed on Au nanorods by using a simple successive reduction growth. Then, the island growth mode of Pt on the Au rod was employed to guide the growth behavior of Au-nanoisland. Because of the high dielectric sensitivity of the Au nanostructures, tiny changes in the shell structure can be readily seen from absorption spectra and electromagnetic field enhancement. Simulations of absorption spectra and the electromagnetic field enhancement using the finite difference time domain (FDTD) method and taking into account the real shapes of the core–shell nanostructures were reported. The accuracy and validity of the FDTD method were verified. The results presented here indicated that surface plasmon resonances of these core–shell metallic nanostructures produce strong effects in both the near- and far-field optical responses.