Plasmonic nanoparticle modified substrate for SERS sensing applications

Numerous research on the toxicity of N-derived species like nitrite and ammonia have been conducted as a result of their widespread existence in the environment. The ecological system is threatened by nutrient pollution, which is mostly caused by heavy use of fertilizers. Another source of pollution is the industrial gas chimneys and internal combustion engines. Numerous analytical techniques, such as chromatography ,electrochemistry and colorimetry have been developed for the study of nitrite ions in the literature. Another advantage of developing NOx and NH3 detection devices is that they play a role in disease identification. Nitrite and ammonia are biomarkers used to diagnose lung and respiratory disorders, as well as kidney and digestive system diseases. Surface-Enhanced Raman scattering (SERS), due to its high sensitivity and resolution, has been extensively researched since its discovery on a rough Ag surface. Up to now, anisotropic noble metal nanostructures (Ag and Au) with tunable absorption bands in a wide spectral range have demonstrated high SERS activity via electromagnetic enhancement mechanism (EM). This dissertation is concerned with the manufacture of plasmonic metal particle substrates and their application to the detection of N-derived molecules. The first two parts present the synthesis of nanoparticles on copper plates. Ag and Au nanoparticle modified copper films with different morphologies are investigated. The homogeneous distribution of Ag and Au nanoparticles on the Cu surface resulted from successful assembly of nanoparticles and surface characteristics of the used copper plate. The final section presents the production of nanoparticles on a 3-D graphene oxide framework. Three-dimensional (3D) graphene materials with distinct characteristics have not yet been substantially investigated for SERS applications. Graphene aerogels (GA) with Ag modifications were used as SERS substrates in this research. SERS performance of substrates were examined by detecting an N-derived probe molecule; Rhodamine B (RhB). The highest-sensitivity substrate is then used for nitrite detection. The detection limit for RhB molecules is 10-8 M for Ag NPs modified Cu substrate, 10-16 M for Au-Ag NPs modified substrate, and 10-6 for Ag NPs modified GA substrate. The SERRS technique (Surface Enhanced Resonance Raman Spectroscopy) was used to study nitrite detection adopting azo dye production. The most promising substrate could achieve detecting nitrite concentrations as low as 10-14M.