Arrays of Cone‐Shaped ZnO Nanorods Decorated with Ag Nanoparticles as 3D Surface‐Enhanced Raman Scattering Substrates for Rapid Detection of Trace Polychlorinated Biphenyls

Abstract A new, highly sensitive and uniform three‐dimensional (3D) hybrid surface‐enhanced Raman scattering (SERS) substrate has been achieved via simultaneously assembling small Ag nanoparticles (Ag‐NPs) and large Ag spheres onto the side surface and the top ends of large‐scale vertically aligned cone‐shaped ZnO nanorods (ZnO‐NRs), respectively. This 3D hybrid substrate manifests high SERS sensitivity to rhodamine and a detection limit as low as 10 −11 M to polychlorinated biphenyl (PCB) 77—a kind of persistent organic pollutants as global environmental hazard. Three kinds of inter‐Ag‐NP gaps in 3D geometry create a huge number of SERS “hot spots” that mainly contribute to the high SERS sensitivity. Moreover, the supporting chemical enhancement effect of ZnO‐NRs and the better enrichment effect ascribed to the large surface area of the substrate also help to achieve a lower detection limit. The arrays of cone‐shaped ZnO‐NRs decorated with Ag‐NPs on their side surface and large Ag spheres on the top ends have potentials in SERS‐based rapid detection of trace PCBs.