Fabrication of Vertically Aligned ZnO Nanorods Modified with Dense Silver Nanoparticles as Effective SERS Substrates

Surface-enhanced Raman scattering (SERS) spectroscopy has attracted increasing attention due to its high spectral reproducibility and unique selectivity to target molecules. Here, a facile approach is proposed to prepare Ag nanoparticles modified ZnO nanorod arrays (Ag/ZnO NR arrays). Ag nanoparticles were densely decorated on the surface of ZnO nanorods through silver mirror reaction and subsequent seed-assisted electrodeposition. The prepared Ag/ZnO NR arrays can be used as a sensitive, uniform, and repeatable SERS substrate for the rapid detection of organic dye molecules and biomolecules with concentrations higher than the corresponding limits of detection (LODs). The LODs for rhodamine 6G (R6G), 4-aminothiophenol (PATP) and adenine are calculated to be 1.0 × 10−13 M, 1.6 × 10−12 M and 3 × 10−11 M, respectively. The enhancement factor (EF) of the SERS substrate is estimated to be as high as ~2.7 × 108 when detecting 10−10 M R6G. Particularly, the as-synthesized substrate exhibits high selectivity to multiple components. In addition, the fabricated Ag/ZnO NR arrays can be recycled due to their superior self-cleaning ability and can realize photocatalytic degradation of R6G in water within 1 h driven by UV light, showing that the three-dimensional recyclable SERS substrates have wide applications in environmental pollution monitoring and biomedical analysis.