Hierarchically rough CuO/Ag composite film with controlled morphology as recyclable SERS-active substrate

Oxide semiconductor combined with noble metal nanocomposites have attracted extensive attention because of its excellent surface-enhanced Raman scattering (SERS) effect and photocatalytic degradation ability which can be applied repeatedly to the detection of pollutants. In this work, hierarchically rough copper oxide (CuO) was first prepared on the surface of copper foil by anodic oxidation, and then loaded silver nanoparticles layer by magnetron sputtering method to obtain CuO/Ag composite film. Such CuO/Ag composite substrate exhibits good SERS performance and recyclability due to its efficient photocatalytic degradation ability. Using Rhodamine 6G (R6G) molecules as probe molecules, the influence of the surface hierarchically rough micro/nanostructures, and the amounts of Ag nanoparticles covered on the CuO film surface were both studied in detail. Using optimized CuO/Ag composite film as SERS active substrate, the detection limit of R6G molecules and crystal violet (CV) molecules were as low as 10−11 M and 10−10 M, respectively. The evolution diagram of Raman spectra shows that such substrate can use its own photocatalytic performance to degrade surface adsorbed molecules under light irradiation, so as to achieve self-cleaning and reusable. After repeated use, the SERS performance was only slightly degraded, showing excellent reusability. For the detection of thiram, we found a limit concentration of 10−8 M. In addition, on the basis of material surface morphology and charge transfer, the SERS enhanced mechanism and photocatalytic mechanism were proposed and discussed. The as-prepared hierarchically rough CuO/Ag composite film is expected to be applied to efficient SERS sensors.