Figure 4.

Plasmonic tuning of metal nanoparticles through templated synthesis of core–shell nanorods using plant polyphenol-inspired coatings. A) Z-contrast TEM and EDS elemental micrographs of Au-PG-Ag NRs prepared with increasing AgNO₃ concentrations (top to bottom). B) A blue shift of the longitudinal surface plasmon resonance wavelength was indicated by a color change of the nanorod suspension. The magnitude of the blue shift was controlled by the concentration of silver nitrate (μm) used in nanoparticle modification. C) Normalized optical extinction spectra of Au-PG-Ag NRs illustrating plasmon tuning through control of the Ag shell thickness.