Ordered arrays of Ag nanodendrite clusters as effective surface-enhanced Raman scattering substrates

We report a cheap synthetic approach to large-area ordered Ag nanodendrite cluster arrays as effective surface-enhanced Raman scattering (SERS) substrates, on a Zn plate coated with periodical porous photoresist via galvanic replacement reaction of Zn and AgNO3 in aqueous solution. Due to the geometrical confinement of the porous photoresist template coated on the Zn plate, the well-positioned Ag nanodendrite clusters are distributed on the Zn plate in ordered arrays. It is demonstrated that citric acid is essential to the formation of the nanodendrite cluster arrays. The resultant Ag nanodendrite cluster arrays not only have high SERS-activity to rhodamine 6G with good signal reproducibility but also can identify thiram (a widely-used pesticide) even at 0.1 mu M level, showing potential in SERS-based detection of pesticide remnants in the environment.