Metal-organic framework engineered corn-like SERS active Ag@Carbon with controllable spacing distance for tracking trace amount of organic compounds

Probing water-soluble organic compounds via Surface-enhanced Raman scattering (SERS) technique could be helpful to prevent harmful impacts of polluted water. A key limitation of restraining SERS technique in probing these pollutants is the difficulty to control the spacing distance of plasmonic nanoparticles within 10 nm so that SERS effect can be efficiently induced. Herein, a strategy of mass-producing Ag-based SERS active material with tunable spacing distance is reported. In brevity, metal-organic framework (MOF) engineered corn-like Ag@Carbon is synthesized by simply thermal treating Ag-MOF. The thermal treatment in-situ turns Ag⁺ into Ag nanoparticles (NPs), resulting in Ag NPs well-dispersed on the surface of the carbonized MOF and forming ordered SERS hotspots. Due to the spatial distance of Ag⁺ directly depends on the molecular diameter of MOF organic ligands, spacing distance of Ag NP is fixed at around 7 nm. Theoretical analysis and experimental study confirm that the uniformly distributed Ag NPs lead to desirable SERS activity. Further study evidences the presented corn-like Ag@Carbon could be a good candidate for tacking organic compounds with satisfactory sensitivity, specificity and low detection limit (10^-8 M). Conclusively, these impressive results indicate a bright future of adopting the proposed strategy to design future SERS active materials.