Surface-enhanced Raman scattering (SERS), owing to its high sensitivity and rapid response, has been widely used in various fields. However, it is still a challenge to prepare SERS substrates with high stability and reproducibility. Metal–organic frameworks (MOFs), with excellent enrichment capacity and stability, provide a new material for high-performance SERS substrates. In this paper, we prepare a MIL-101­(Cr) film via a secondary growth method, and Ag+ is reduced to Ag NPs by UV irradiation and attach to the film to synthesize the Ag@MIL-101­(Cr) film SERS substrate. Then, we change the time of UV light illumination and the amount of silver nitrate in order to obtain the optimal substrate. The detection capability of this sample can be up to 10–11 M for 4-ATP, and the relative standard deviation (RSD) is only about 5%, which demonstrates that the substrate has excellent SERS effect and reproducibility. Finally, the prepared substrate has been applied for the determination of nitrofurantoin, with its detection capability up to 10–7 M. This work proposes a simple method to synthesize MOF-based film substrate with high SERS performance and uniformity and provides potential for the sensitive detection of chemical or antibiotic residue.

The spectroscopy of surface-enhanced Raman scattering (SERS), with its high sensitivity and specific chemical fingerprinting, has received increasing attention. A stable substrate is extraordinarily important for the trace detection of the SERS technique, but the challenge of SERS substrate production with high stability and uniformity still imposes the unavoidable barriers. In this paper, we design a multilayer core−shell-nanostructured ZrO 2 @Ag@SiO 2 nanoparticle through liquid extraction. First, we regulated the usage of AgNO 3 (1 wt %) to obtain Ag@SiO 2 which is silver coated with uniform distribution; on the surface of silica, the number of silver particles is abundant. Then, we discussed the influence when different concentrations of zirconium propoxide are added on the zirconia layer's thickness. Then, we applied FDTD simulation to explain the position of SERS "hotpots" with and without ZrO 2 coating. We have found that the detection capability of ZrO 2 @Ag@SiO 2 can be up to 10 −9 M for 4-ATP; with ZrO 2 @Ag@SiO 2 SERS substrates exposed to the atmospheric environment for up to 30 days, we could still obtain the excellent SERS signal performance contributed by the good chemical stability of ZrO 2 , when ZrO 2 is coated on the surface of Ag@SiO 2 , the zirconia layer formed has a protective role . These experimental results have indicated that the outer zirconia layer could prevent the silver surface from being oxidized, ensuring its stability , which is quite crucial for the applied SERS.