Controllable fabrication of Ag-nanoplate-decorated PAN-nanopillar arrays and their application in surface-enhanced Raman scattering

Abstract

We report a facile and low-cost approach for fabrication of large-scale surface-enhanced Raman scattering (SERS) active substrates composed of Ag-nanoplates (Ag-NPs) decorated polyacrylonitrile nanopillar (denoted as Ag-NPs@PAN-nanopillar) arrays, via a consecutive process of molding PAN-nanopillar arrays, sputtering Au-nanoparticles onto the PAN-nanopillar arrays as a conducting layer, and decorating the PAN-nanopillars with Ag-nanoplates. The Ag-nanoplate distribution density on the PAN-nanopillars can be tailored by tuning the concentration of citric acid and the Ag-deposition duration, and high SERS sensitivity can thus be achieved by optimizing the density of Ag-nanoplates. The adjacent Ag-nanoplates induced "hot spots" are densely and uniformly distributed in the three dimensional (3D) space around the PAN-nanopillar arrays, and thus Ag-NPs@PAN-nanopillar arrays generated sensitive and homogenous SERS signals when using rhodamine 6G as a probed molecule. Using the Ag-NPs@PAN-nanopillar arrays as SERS substrates, 10-7 M methyl parathion (organophosphorus insecticide) and 10-6 M PCB-77 (one congener of polychlorinated biphenyls belonging to persistent organic pollutants) are identified. Therefore the SERS-active substrates have potential in SERS-based rapid detection of environmental organic pollutants.