Hybridization between cellulose nanofibrils and faceted silver nanoparticles used with surface enhanced Raman scattering for trace dye detection.

This research studies the surface enhanced Raman scattering (SERS) activity of cellulose nanofibrils (CNFs) hybridized with faceted silver nanoparticles (AgFNPs) for the detection of organic dyes in aqueous media. Faceted AgNPs were synthesized under environmentally benign conditions using TEMPO-oxidized CNFs as both shape-regulating, reducing and stabilizing agents. Small, zero valent, spherical AgNPs first formed on the CNF surface and transformed into larger and faceted AgNPs when reacting with H2O2 through a thermodynamically driven Ostwald ripening mechanism. The as-synthesized hybrids exhibited strong analytical enhancement in the Raman signal of methylene blue, up to 6.8 × 103 at 448 cm-1 with less than 32% spatial variations and 10% sample-to-sample variability, enabling the detection of dyes in water at the sub part-per million level. The origin of the SERS enhancement came from discrete hotspots of high silver content on the substrate, as characterized by spatially resolved laser ablation inductively coupled plasma mass spectrometry.