ZnO nanotower arrays decorated with cubic and tetrahedral shaped Ag-NPs as hybrid SERS-active substrates

Ag/ZnO hybrid surface-enhanced Raman scattering (SERS) substrates laden with 3D hot-spots and electron transfer (ET) resonance, which can generate large Raman signals enhancement, have attracted extensive attention in recent years. This work fabricated the cube and tetrahedron shaped Ag-nanoparticles (Ag-NPs) with corners and an average particle size of similar to 60 nm by solvothermal method, then anchored the Ag-NPs on ZnO nanotower arrays with laminated nanosteps by drop-casting without surface modifiers to obtain the Ag-NPs/ZnO nanotower (AZT) SERS substrates. This AZT substrate manifests high SERS EF (6.9 x 10(13)) to rhodamine 6G (R6G) and a low detection limit (1 x 10(-18) M). The high SERS sensitivity benefits from not only the combination of the two kinds of hot-spots, i.e. the nanogaps and the corners of Ag-NPs, but also the retaining of R6G molecules on the nanosteps of ZnO nanotowers, by which the R6G molecules can access the hot-spots regions. This study provides a bran-new approach for optimizing the performance of SERS substrates.

Automated summary

This study fabricated Ag/ZnO hybrid SERS substrates with high sensitivity and low detection limit by anchoring Ag nanoparticles on ZnO nanotower arrays without surface modifiers. The high SERS sensitivity is attributed to a combination of nanogaps and corners of Ag-NPs, as well as the retention of R6G molecules on ZnO nanotower nanosteps, allowing the molecules to access the hot-spot regions.