Preparation and Surface Enhanced Raman Spectroscopy of Au/TiN Composite Films

Surface-enhanced Raman scattering spectroscopy (SERS) has been used in environmental monitoring, biomedicine, food hygiene, etc. , and high-activity SERS substrates are the key to the application of surface-enhanced Raman scattering spectroscopy. As a novel plasma material, TiN has strong SERS performance, and also has good chemical stability and biocompatibility, but its SERS performance is not as strong as that of precious metal gold and silver. For this reason, the Au/TiN composite films were prepared by depositing noble metal Au nanoparticles on the surface of TiN films using ammonia reduction nitridation and electrochemical deposition method. There were metal Au and TiN in Au/TiN composite film. With the increase of electrochemical deposition time, the number of metal gold nanoparticles on the surface of TiN film increased gradually and the size increased. The absorption peak of Au/TiN composite films moved, which was due to the intrinsic surface plasmon resonance coupling of gold and TiN. The SERS performance of the Au/TiN composite film was analyzed by using Rhodamine 6G as Raman probe molecule. It was found that the Raman peak signal intensity of the R6G probe molecule on the Au/TiN composite film increased firstly and then decreased as different deposition times increased. When the electrochemical deposition time was 5 min, the R6G Raman signal peak was the highest, and the composite film showed the strongest SERS activity. The Au/TiN composite film and Au film were immersed in 10(-3), 10(-5), 10(-7), 10(-8) and 10(-9) mol . L-1 of R6G solutions for 5 min, respectively. The Au/TiN composite film enhancement factor reached 8. 82 X 10(5), and the detection limit was 10 a mol . L-1. Compared with the Au film and the TiN film, the Raman signal of the R6G probe molecule on the Au/TiN composite film was the highest. This was due to the coupling effect of surface plasma in Au/TiN composite film, which enhanced the intensity of local electromagnetic field and enhanced the Raman signal of R6G probe molecule. The 2D-FDTD simulated electric field distribution showed that the Au/TiN composite film, the Au film and the TiN film all had an electric field enhancement effect, and the Au/TiN composite film had a particularly strong reinforcing effect, which confirmd the coupling effect between titanium nitride and gold. It was also found that there may be charge transfer between TiN and Au, which promoted the oxidation of 4-aminobenzenethiophenol, which confirmed the synergistic effect of TiN and Au film. Furthermore, the Au/TiN composite film had good uniformity with a relative average deviation of 7. 58%. It could be seen that the Au/TiN composite film as prepared has potential application for SERS substrate.