Seed-assisted electrodeposition of multilayer Au nanoparticles-assembled films for sensitive surface-enhanced Raman scattering detection

Abstract

Surface-enhanced Raman scattering (SERS) spectroscopy can be used to realize sensitive rapid detection of molecules. Three-dimensional (3D) SERS substrates can provide more hotspots within the excitation laser beam when compared with the corresponding two-dimensional (2D) SERS substrates. Most of the methods for fabrication of 3D SERS substrates involve complex processes. Therefore, it is significant to develop a simple and effective method for fabrication of 3D SERS substrates. Here, a seed-assisted electrodeposition approach is developed for fabrication of a 3D SERS substrate composed of multilayer Au nanoparticles. Interestingly, it is demonstrated that a uniform film composed of multilayer Au nanoparticles that can serve as a 3D SERS substrate can be achieved directly by one-step electrodeposition on a conductive surface coated with monolayer Au seeds. It is found that a diffusion-controlled growth during electrodeposition narrows the nanoparticle size distribution and results monosized Au nanoparticles. The as-prepared multilayer Au nanoparticles-assembled film shows high SERS sensitivity and good spectral uniformity. For SERS detection of rhodamine 6G, a limit of detection as low as 3.4×10−12 M has been achieved. Moreover, good spectral uniformity (relative standard deviation ∼7.8%) and high substrate-to-substrate reproducibility (relative standard deviation ∼8.6%) have also been demonstrated. The as-prepared multilayer Au nanoparticles-assembled film is used to detect organic pollutants such as dye molecule crystal violet (CV) and methylene blue (MB). Calibration curves with a linear correlation between the logarithmic SERS intensity and logarithmic concentration of CV and MB have been obtained. Limit of detections for CV and MB are 1.2×10−8 M and 9.8×10−10 M, respectively. Therefore, the fabricated 3D SERS substrate has good application prospects in sensitive detection of organic molecules.