Improved performance of surface-enhanced Raman scattering on silver substrates prepared in nitric acid solutions

In this work, we propose a new electrochemical method to prepare surface-enhanced Raman scattering (SERS)-active silver substrates in nitric acid solutions. Experimental results indicate that the SERS intensity of adsorbed Rhodamine 6G (R6G) can be significantly increased, as compared with that of R6G adsorbed on a SERS-active Ag substrate prepared by an electrochemical method in a chloride-containing solution, which was generally employed in the literature. Moreover, the SERS of R6G on the newly developed substrate (prepared in a nitric acid solution) still performs well at a high temperature of 250°C. However, the enhancement capability of the SERS-active substrate prepared in a chloride-containing solution is seriously destroyed at temperatures higher than 150°C. Further investigations indicate that the oxidation states of roughened Ag substrates prepared in nitric acid solutions under different experiment conditions have less influence on the corresponding SERS performances. Instead, different surface morphologies of roughened Ag substrates and different contents of nitrogen-containing dopping ions on the roughened Ag substrates demonstrate significant effects on the corresponding SERS performances.