Asymmetric Ag Nanocrescents with Pt Rims: Wet-Chemical Synthesis and Optical Characterization

Abstract

A rational and controllable synthetic method for asymmetric nanoparticles in the solution phase is very rare and remains a major challenge. Among pseudo-two-dimensional nanoparticles, plasmonically active asymmetric nanocrescents have been intensively investigated because of their unique strong near-field enhancement and light confinement at the tips. Herein, we demonstrate the synthesis of highly uniform Ag-dominant nanocrescents with Pt rims (AgPtrim NCs) in an aqueous medium, by adopting Pt split rings as a scaffold for asymmetric growth. The asymmetric nanocrescents collectively exhibited characteristic localized surface plasmon resonance bands, including in-plane and out-of-plane modes, which matched the calculated spectrum of a single Ag nanocrescent, demonstrating the high level of uniformity of the synthesized nanocrescents. We observed light confinement and field enhancement at the sharp tips of the AgPtrim NCs by comparing their Raman intensity with that from their analogous nanodisks.