Growth of sea-urchin-like platinum nanoparticles and their applications

Platinum nanoparticles with sea-urchin-like morphology were synthesized on Si substrates by using the fluoride-assisted galvanic replacement reaction. The size, density, and crystallinity of the nanoparticles were controlled by adjusting the reaction time; a longer synthesis time resulted in higher Pt content and lower reflectance in the visible range. X-ray photoelectron spectroscopy confirmed the presence of both Pt⁰ and Pt^II species. The sample obtained under a reaction time of 15 min exhibited the strongest surface-enhanced Raman scattering (SERS) due to its optimal nanospike architecture. Annealing at 600°C transformed the sample obtained after a 5 min reaction time into smoother structures, improving crystallinity but reducing hydrophobicity and SERS activity. The results highlight how Pt sea-urchin-like nanostructure morphology governs the material's optical, surface, and sensing properties, offering a tunable platform for plasmonic sensing, and antireflective applications.