A Dual-Nanostructured Approach to SERS Amenable to Large-Scale Production

Abstract

A DUAL-NANOSTRUCTURED APPROACH TO SERS AMENABLE TO LARGE-SCALE PRODUCTION Kory Brian Castro Old Dominion University, 2019 Director: Dr. John Cooper A SERS device was made using a dual-nanostructured surface comprised of silver nanoparticle and silver nanowires. The ability of each nanostructure to produce a uniform surface was characterized and the surface-enhanced Raman scattering (SERS) response of the resulting surfaces were examined using the reporter molecule 4aminothiolphenol (ATP) and a 638 nm excitation laser. A synthetic method was developed to produce silver nanowires with lengths of ~20 μm and diameters of ~100 nm with a narrow size distribution. The method utilized a simple, one-pot synthesis that is amenable to large-scale production. A selective precipitation method was used to the isolate the ~200 aspect ratio silver nanowires in a high purity. The wires were Mayer rod coated onto glass slides to produce uniform surfaces with ease. The SERS response was found to be highly variable depending on the sampled location. An enhancement factor of 2.2x105 was tentatively assigned using the 1600 cm-1 peak of ATP. The silver complex μ-oxolato-bis(ethylenediaminesilver(I)) was synthesized as reported in the literature. The aqueous solution of the complex was thermally decomposed to produce SERS-active silver surfaces on glass slides. The silver complex was unable to generate a uniform surface coating without the use of additives. By dropcasting the complex at the decomposition temperature, surfaces were generated exhibiting ~75 nm, spherical nanoparticles. The surface was found to be SERS-active, however the poor processing characteristics of the complex prevent its applicability to large-scale device production. Silver nanowire surfaces were used as substrates to Mayer rod coat the silver complex uniformly without the use of additives. This provided the proof-of-concept that the dual-nanostructured surface is amenable to large scale production through the use of roll-to-roll printing. A dual-nanostructured surface was produced by dropcasting the complex on silver nanowire surfaces to mimic the quality of surface achievable by an industrial production line. The dual-nanostructured surface produced a spatially consistent SERS response and an enhancement factor of 4.3x105 was tentatively assigned using the 1600 cm-1 peak of ATP.