Three dimensional noble metal-metal organic framework composite as SERS substrate for efficient capture and detection of pesticides

Hybrids of noble metal and metal-organic framework (MOF) are promising substrates for molecule sensing by surface enhanced Raman scattering (SERS) technique. However, most of these composite SERS substrates are zero-dimensional (0D) or two-dimensional (2D) structures, limiting their efficiency in adsorption and Raman enhancement. In this work, a new three-dimensional (3D) SERS substrate CC/ZnO-Ag@ZIF-8 composed of carbon cloth (CC) supported ZnO nanorod array decorated with AgNPs and coated with ZIF-8 layer was prepared for sensitive detection of pesticide. Compared with common 0D/2D substrates, the synergy of ZnO, AgNPs and MOF in 3D space achieved the highly efficient utilization of each component's advantages, greatly enhancing the adsorption capacity to analyte and significantly amplifying the EM enhancement effect. Consequently, the 3D SERS substrate showed high SERS sensitivity to pesticide intermediate 4-ATP with a detection of limit (LOD) as low as 10−10 M, which is 3 orders of magnitude lower than its 2D counterpart CC/Ag@ZIF-8, or 2 orders of magnitude lower than that of CC/ZnO-Ag without MOF coating. Additionally, ZIF-8 coating also improves the stability, anti-interference ability and signal consistency of the substrate. Finally, the 3D CC/ZnO-Ag@ZIF-8 was successfully applied to the quantitative analysis of pesticide thiram in real lake water sample, which achieved a linear range of 10−5 to 10−9 M and a LOD of 1 nM. Such 3D noble metal-MOF hybrid SERS substrate with multiple merits in adsorption, Raman enhancement, stability and reproducibility holds great promise in environmental analysis.