In situ preparation of silver nanoparticles on polyaniline nanofibers for SERS applications

Plasmonic silver nanoparticles (AgNPs) were prepared using polyaniline (PANI) as a reducing agent. These PANI/metallic nanoparticles nanocomposites have been used as surface-enhanced Raman spectroscopy (SERS) substrates using Nile Blue dye as a molecule probe. Since the Raman signal enhancement is directly associated with the size and shape of NPs, their morphological control is a challenge for the area. PANI nanofibers have a large surface area, are ideal for AgNPs synthesis, and present simple and fast preparation. In this work, these nanofibers were doped with hydrochloric, citric, phosphoric, mandelic, or p-toluenesulfonic acids and synthesized AgNPs with different morphologies. Also, the dedoped form (Emeraldine base) was used. The variations in the morphology and distribution of AgNPs induced by the surface properties of PANI nanofibers due to different dopants result in distinct SERS enhancements. UV-Vis and Raman spectroscopy show the PANI films oxidation after the AgNPs formation.