Synergetic SEIRA sensing and catalytic performance of Au nanostars embedded onto dielectric silica spheres

Light-matter interaction involving metal nanoparticles promotes sensing applications like surface-enhanced infrared absorption (SEIRA) and surface-enhanced Raman scattering (SERS), tuned over the entire visible frequency range utilizing the dielectric constant of the surrounding medium. Based on this simple yet significant aspect, we envisage core-shell nanostructures having a dielectric core and metal shell, reaping the benefit of diverse functionalities rolled in one single nanostructure. We indigenously develop an effective single-step synthesis protocol for fabricating silica spheres embedded with Au nanostars and vice versa in a seamless manner, validated through careful analytical and microscopic signatures. We also examine these metastructures using FDTD (finite difference time domain) simulation corroborated with the experimental data, visually representing the near-field enhancement effects in an effortless manner. SEIRA measurements essentially assess the invariably enhanced sensing of respective dyes, bromophenol (BP) and crystal violet, on the surface of our core-shell structures, both in their individual as well as mixed states, harnessing the highest selective dye enhancement to the best of knowledge. Additionally, Au nanostar-decorated silica spheres monitor the dye degradation at the molecular level through FTIR vibrational data analysis. Our present results elucidate synergistic effects between dielectric core and anisotropic-shaped metal shells, illustrating enhanced optical properties and catalytic functionalities, holding promise for advanced sensing platforms with improved performance and versatility.