Precision Synthesis of Symmetrical Stellated Icosahedrons for Tailored Plasmonics and Magnetic Assembly

Symmetrically branched metal nanostructures with intricate structural features and exceptional physicochemical properties demonstrate a significant potential for diverse applications. Nevertheless, achieving precise morphological control over these nanostructures with adjustable dimensions poses a considerable challenge, especially for stellated icosahedrons (STICs) with 20 orderly arranged branches. Here, we present a template replication strategy for the controllable synthesis of metal STICs with various compositions, featuring high yield, uniformity, and adjustable dimensions. The synthesis relies on fine-tuning the reduction kinetics toward heterogeneous nucleation and growth through optimizing the reduction potential of the metal precursors. Notably, the synthesized Au STICs exhibit tunable localized surface plasmon resonances and scattering spectra by varying their sizes as well as profound surface-enhanced Raman scattering (SERS) activity. Electron energy-loss spectroscopy and numerical simulations confirm the symmetrical distribution of their surface plasmon resonances, enabling the polarization-angle-dependent SERS enhancement. Moreover, the resulting magnetic Ni-NiP_<i>x</i> STICs exhibit chain-like self-assembly under magnetic fields. This work offers an approach to the rational synthesis of branched nanostructures with complex and intricate architectures that hold significant promise for applications in SERS and catalysis.