In situ creation of surface-enhanced raman scattering active au-auo _x nanostructures through electrochemical process for pigment detection

Roughing the metallic surface via oxidation-reduction cycles (ORC) to integrate the surface plasmon resonance and surface-enhanced Raman scattering (SERS) is predominant in developing sensor systems because of the facile preparation and uniform distribution of nanostructures. Herein, we proposed a distinctive ORC process: the forward potential passed through the oxidation of Au and reached the oxygen evolution reaction, and once the potential briefly remained at the vertex, the various reverse rates were employed to control the reduction state. The created hybrid Au-AuO_x possessed electromagnetic and chemical enhancements concurrently, wherein the rough surface provided the strong local electromagnetic fields and significant interaction between AuO_x and molecule to improve the charge transfer. The synergistic effects significantly amplified the intensity of Raman signal with an enhancement factor of 5.5 × 10⁶ under the optimal conditions. Furthermore, the prepared SERS substrate can simultaneously identify and quantify the mixed edible pigments, Brilliant Blue FCF and Indigo Carmine, individually. This result suggested that the development of SERS sensor based on the proposed SERS-activated methodology is feasible and reliable.