Synthesis of Silver Core-Tin Oxide Shell Nanoparticles for Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy

The research describes a new method for silver core-tin oxide shell nanoparticle preparation suitable for shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) investigation. The two-step synthesis was performed without intermediate separation. Silver nitrate precursor, sodium citrate reducer, and diethylene glycol stabilizer were used resulting in the formation of large (80 ± 5 nm) silver nanospheres. A thin (8 – 12 nm) tin oxide shell was successfully produced in 40 minutes in an alkaline solution. The synthesized silver core-tin oxide shell nanoparticles demonstrated good stability in weakly acidic (pH 5), neutral (pH 7), and basic (pH 9) media. Long-term (2 – 4 months) stability experiments were also successfully performed in water, acetone, and ethanol. The nanoparticles were applied in the SHINERS study of the classic 4-mercaptobenzoic acid monolayer on Au, highlighting their potential for wider analytical application. The paper provides a detailed explanation of the synthesis, analysis, and application of the silver core-tin oxide shell nanoparticles based on data from UV-Vis, HR-TEM, and SHINERS.