3D CuO/NiCo/Ag hierarchical SERS nanostructures for direct detection of trace perfluorooctanoic acid

Abstract

Perfluorooctanoic acid (PFOA), a ubiquitous emerging contaminant in global aquatic environments, poses significant challenges for Raman spectroscopic detection due to its inherent molecular properties, including high toxicity and extreme persistence. To address this limitation, we engineered a three-dimensional hierarchical nanostructure based on CuO nanowire (NW)/layered double hydroxide (LDH)/silver (Ag) as a surface-enhanced Raman scattering (SERS) substrate. Within this architecture, electrostatic interactions between the LDH component and PFOA molecules significantly enhance the efficient adsorption of the target analyte. Concurrently, the uniform distribution of Ag nanoparticles ( NPs) across the substrate surface generates intense localized plasmonic hotspots under light-trapping effect, which is crucial for Raman signal amplification. Consequently, this substrate enables the direct detection of trace PFOA across a wide dynamic range (10⁻² to 10⁻⁹ M). This capability facilitates the effective and direct identification of PFOA molecules without requiring complex pretreatment or indirect labeling procedures. These results demonstrate the substantial potential of the CuO NW/LDH/Ag structure for highly sensitive, direct SERS-based monitoring of organic pollutants such as PFOA.