Coconcentration/Colocation Effects of Quasi Fabry–Pérot Cavity Structure with Anti‐Interference Feature on Light and Analytes: Accurate Raman Detection of Hg²⁺ under Diverse Real Environments

Abstract A quasi Fabry–Pérot (F–P) cavity structure of zinc oxide/sliver nanowires coated with zeolitic imidazolate framework‐8 (ZnO/Ag NWs/ZIF‐8) is designed to precisely guide target analytes into the hotspot zones while hindering the entry of various potential interferents during Raman detection. Owing to the triple synergistic effect of the ZIF‐8 dielectric F–P cavity, ZIF‐8 microsponge, and backward light scattering caused by the ZnO/Ag NW tip, the structure of ZnO/Ag NWs/ZIF‐8 is verified to have unique coconcentration and colocation effects on light and analytes. The molecular sieving effect of the ZIF‐8 layer and the selectivity of the premodified reporter probe on ZnO/Ag NWs endow the ZnO/Ag NWs/ZIF‐8 with an important anti‐interference feature for diverse interferents in practical Raman detection of heavy‐metal ions. The analytical enhancement factor of ZnO/Ag NWs/ZIF‐8 is as high as 3.97 × 10⁶, with a limit of detection for Hg²⁺ reaching 10⁻¹⁰ M; and the relative standard deviation is only 6.03%. The structure directly and successfully attains accurate Raman detection of diverse real samples containing Hg²⁺, without an additional pre‐extraction process. This research provides a novel way of improving Raman detection reliability under real scenarios and is a new attempt to precisely manipulate light and analytes by controlling the dielectric.