Large-area Co(OH)2 nanoflower array films decorated with Ag nanoparticles as sensitive SERS substrates†
Large-area three-dimensional (3D) well-ordered Co(OH)2 nanoflower array films decorated with Ag nanoparticles (Ag NPs) with a novel structure were designed as sensitive SERS substrates for trace detection of pesticides. Co(OH)2 nanoflowers were electrodeposited on the surface of molded polyacrylonitrile (PAN) films with ordered nanopillar arrays and then Ag NPs were sputtered onto of the surface of each Co(OH)2 nanoflower. The SERS performance of the as-prepared films can be optimized by tuning the Ag-sputtering duration and the morphology of the Co(OH)2 nanoflower arrays. Owing to the formation of high-density SERS “hotspots” created in the nanogaps between the adjacent Ag NPs located on the same and neighbouring Co(OH)2 nanosheets, the optimized substrates show SERS activity for probe molecules. As a result, 10−11 M rhodamine 6G and 10−9 M 4-aminothiophenol can be SERS recognized, respectively. To verify their practical application, the optimized SERS substrates were employed for trace detection of thiram (a type of pesticide), and 10−9 M thiram can be recognized, showing great potential in pesticide detection.