Bimetallic flowers, beads, and buds: synthesis, characterization, and Raman imaging of unique mesostructures.
We demonstrate the creation of a new class of nano/mesostructures, such as Au/Ag flowers, Au/Pt buds, and Au/Pt beads, through the directed overgrowth of Ag or Pt on Au/oligoaniline nanowires (Au/OA NWs). Different stages of the formation of these mesostructures have been studied using various spectroscopic and microscopic techniques. The surface plasmon resonance (SPR) of the Au/OA NWs can be tuned by the incorporation of bimetallicity into the nanowire. Raman based spectral imaging of the bimetallic Au/Ag mesoflower and Au/Pt mesobud revealed the molecular details and the nature of interaction of oligoaniline with the different metal domains. Raman study also suggested a substrate effect due to the different domains of the mesostructures, and spectral images distinguished these two regions. The single particle spectral images suggest that the material is surface-enhanced Raman active.
DST Unit on Nanoscience (DST UNS), Department of Chemistry and Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai - 600 036, India.
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Sajanlal
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Pradeep