High Sensitive Seawater Resistant SERS Substrates Based on GoldIsland Film Produced by Electroless Plating

High sensitive seawater resistant SERS (surface-enhanced Raman scattering) substrates based on gold island film were designed by electroless plating solution of chloroauric acid (HAuCl4) and hydrogen peroxide (H2O2) in order to detect pollutions such as Polycyclic Aromatic Hydrocarbons (PAHs) at low concentrations (nmol/l) in the marine environment.By controlling the electroless plating time the SERS substrates were optimized due to their SERS sensitivity for pyrene as a representative PAH.Additionally, shifted excitation Raman difference spectroscopy (SERDS) was applied to suppress the fluorescence background and improve dramaticallythe Raman signals, which yields to a limit of detection (LOD) for pyrene of 1.0(1) nmol/l. Long-term stability tests werecarried out over 12 weeks and show that the SERS activity is only slightly reduced within the first two weeks storage in sea water, after 4 weeks about 50 % and after 8 weeks about 15 % of the activity is still present. The reproducibility of fabricating the substrates is better 8 % and the variance of a single substrate around 2.4 %. The designed SERS substrates are highly sensitive, seawater resistant, reproducible, and can be easily manufactured even during a cruise. Therefore, they are best suited for in-situ detection of PAHs in the marine environment.