Facile synthesis of SERS active Ag nanoparticles in the presence of tri-n-octylphosphine sulfide

A facile and novel way was reported here for the synthesis of hydrophobic Ag nanoparticles (NPs), using AgNO3, tri-n-octylphosphine (TOP) and sulfur (S) powder in process. TOP was used as solvent, reducing agent and stabilizer. S could chelate with excessive TOP to form trioctylphosphine sulfide (TOPS), which served as second capping agent. The hydrophobic Ag NPs could be transformed into hydrophilic state through ligand exchange. Furthermore, surface-enhanced Raman scattering (SERS) spectra of 4-aminothiophenol (4-ATP) were obtained on the hydrophobic and hydrophilic Ag NPs modified substrates, indicating that the as-synthesized Ag NPs had great potential for high sensitive optical detection applications.

Research highlights▶ Hydrophobic Ag nanoparticles were synthesized by using AgNO3, tri-n-octylphosphine and sulfur powder in process. ▶ Tri-n-octylphosphine was used as solvent, reducing agent and stabilizer in the synthetic process. S could chelate with excessive tri-n-octylphosphine to form trioctylphosphine sulfide, which could adjust Ag nanoparticles' growth due to its strong capping ability and served as second capping agent. ▶ Through surface exchange with 3-mercaptopropanoic acid, the hydrophobic Ag nanoparticles could be transformed into hydrophilic ones. ▶ The synthetic strategy was simple and the as-synthesized Ag nanoparticles could be used as substrates for SERS detection.