表面增强拉曼散射光谱（SERS）已用于环境监测、 生物医药、 食品卫生等领域, 而高活性SERS基底是表面增强拉曼散射光谱技术应用的关键。 TiN作为新型等离子材料具有较强的SERS性能, 同时化学稳定性及生物相容性较好, 但其SERS性能不如贵金属金强。 该研究采用氨气还原氮化法和电化学沉积法, 在TiN薄膜表面沉积贵金属Au纳米颗粒制备出Au/TiN复合薄膜。 在Au/TiN复合薄膜中单质Au和TiN两种物相共存； 随着电化学沉积时间延长, TiN薄膜表面单质金纳米颗粒数量逐渐增多, 金纳米颗粒尺寸增大, 颗粒间距减小。 由于金与TiN两者的本征表面等离子共振耦合作用, Au/TiN复合薄膜的共振吸收峰发生了偏移。 利用罗丹明6G为拉曼探针分子, 对Au/TiN复合薄膜进行SERS性能分析, 发现Au/TiN复合薄膜上的R6G探针分子的拉曼峰信号强度随沉积时间延长呈现先增大后减小的规律； 当电化学沉积时间为5 min时, R6G拉曼信号峰较高, 复合薄膜样品的SERS活性最大。 将Au/TiN复合薄膜和Au薄膜分别浸泡在10-3, 10-5, 10-7, 10-8及10-9 mol·L-1R6G溶液5 min, 进行检测限分析, 发现Au/TiN复合薄膜检测极限达10-8 mol·L-1, 增强因子达到8.82×105, 与Au薄膜和TiN薄膜相比, Au/TiN复合薄膜上对R6G探针分子SERS活性最高。 这得益于Au/TiN复合膜中表面等离子体产生的耦合效应, 使得局域电磁场强度增强, 从而引起R6G探针分子拉曼信号增强。 通过2D-FDTD模拟电场分布发现Au/TiN, Au及TiN薄膜具有电场增强作用, 其中Au/TiN复合薄膜的增强作用尤为显著, 这也证实了氮化钛与金纳米颗粒之间存在耦合效应。 另外发现TiN与Au之间可能存在电荷转移, 促进了4-氨基苯硫酚氧化反应, 进而证实了TiN与Au薄膜的协同作用。 此外, Au/TiN复合薄膜均匀性较好, 相对平均偏差仅为7.58%。 由此可见, 采用电化学沉积制备的Au/TiN复合薄膜具有作为SERS基底材料的应用潜力。

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 8.82×105, and the detection limit was 10-8 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.