Multiscale structure enabled effective plasmon coupling and molecular enriching for SERS detection

Abstract

Surface enhanced Raman scattering (SERS), as a molecular-specific spectroscopy method using plasmonic nanostructures to significantly enhance Raman spectroscopy, has broad application prospects in various fileds. In our work, the Ag/CuO nanowires (NWs)/pyramidal PDMS multiscale structure were rationally fabricated as a multi-dimensional plasmon coupling SERS substrate with molecular enrichment effect. CuO NWs were grown in the pyramid cavity by alkaline etching and formed micro-nano multiscale strucure. The Ag film was decorated on the nano-micro multiscale structure by physical vapor deposition method, endowing the SERS activity. The subwavelength-size Ag/CuO NWs can also provide a rough enough surface to separate the droplets from the air, reduce the surface energy, and achieve a hydrophobic effect. To demonstrate the SERS activity, the proposed multiscale micro-nano structure has been successfully applied to sensitively detect Rhodamine 6G (R6G) at low concentration. Interestingly, we also demonstrate that the Ag/CuO NWs/pyramidal PDMS multiscale structure has excellent molecular adsorption for practical application detection. We successfully achieve the detection for the mixture of R6G, Crystal Violet (CV) and Congo Red (CR) molecule under turbid and different PH environment, which demonstrates its great potential for in-situ detection of chemical dye molecules in complex environments.