Hierarchical gold nanoflowers via PIL-mediated facile synthesis: toward ultrasensitive SERS sensing of Rhodamine 6G

To address the limitations of traditional synthesis methods for gold nanostructures, which rely on high temperatures, toxic reagents, and harsh conditions, this study proposes an eco-friendly strategy for synthesizing gold spikelet nanoflowers using poly(ionic liquid) (PIL) as a structure-directing agent. By employing HAuCl 4 as the precursor and ascorbic acid (AA) as the reducing agent, hierarchical Au spikelet nanoflowers with tertiary structure were successfully prepared via a one-pot method in a 60 °C water bath. Systematic investigation of the influencing factors revealed that temperature, AA concentration, and PIL concentration collectively determine the product morphology, with PIL concentration exerting the most significant influence on both the morphology and hierarchical structure of the Au nanoflowers. Using Rhodamine 6G (R6G) as a molecular probe, the resulting substrate exhibited exceptional surface-enhanced Raman scattering (SERS) sensitivity, achieving a detection limit of 10 − 12 M for R6G, which surpasses the performance of most reported Au/Ag-based materials, and demonstrates high reproducibility (< 2% average relative deviation (RAD) from measurements at five randomly selected locations). This work provides a sustainable approach for fabricating high-performance SERS substrates, demonstrating promising potential for applications in biological sensing and diagnostics. Graphical