Double profound enhancements of CuO nano-octahedrons connected by intertwined Ag nanovines for elevating SERS activity toward ultrasensitive pesticide detection.

Recently, hybrid plasmonic metal/semiconductor-based surface-enhanced Raman scattering (SERS) has attracted ever-increasing attention due to its combined characteristics of electromagnetic (EM) enhancement and chemical (CM) enhancement, holding great potential for trace molecular detection. Herein, we demonstrate an interesting heterostructure by linking CuO nano-octahedrons with intertwined Ag nanovines (NVs). The obtained Ag NVs/CuO heterostructures exhibit excellent SERS activity, which is about 2.7 and 7.0 times higher than that of monodispersed Ag or Au nanoparticles (NPs) modified CuO. The intertwined Ag NVs among adjacent CuO octahedrons serve as efficient electron transport channels, which can obviously promote the separation of electrons and holes, reduce the recombination of photogenerated carriers, and then improve the CM enhancement effect. Meanwhile, the accumulated electrons on plasmonic NVs can effectively optimize the collective oscillation of electrons and further improve the EM enhancement. The optimal SERS substrate possesses fascinating multifunctional SERS properties, including ultra-low detection limit (CV, 10 M), excellent anti-interference capability and selectivity. Finally, the established nanosensor can be effectively applied for the quantitative detection of pesticide thiram molecules in soil and biological samples, with low detection limits of 0.48 ng g and 10 M, respectively. The proposed work demonstrates a high-performance SERS heterostructure with both improved CM enhancement and enhanced EM effect by linking adjacent CuO nano-octahedrons with Ag NVs, which is particularly suitable for ultrasensitive residual pesticide detection in real-world environment.