Hierarchical Au Nanoisland Arrays for Anticounterfeiting Surface-Enhanced Raman Scattering Stamps
Qian Li, Feng Liu, Yali Shi, Xun Sun, Bowei Li, Xingguo Liang, Guoqing Wang
Abstract
Plasmonic nanostructures of hierarchy allow for the integration of the functions of different domains and, importantly, provide built-in nanogaps and hotspots due to the intrinsic coupling effect. Although they are badly needed for a range of applications, including surface-enhanced spectroscopies, chem/biosensing, and others, simple and fast preparation of plasmonic hierarchical nanostructures remains a challenging goal. Here, the growth of hierarchical Au nanoisland arrays in a reactant in/target produced fashion is communicated. By a single-step quick injection, uniform Au nanoisland arrays with intense built-in hotspots could be produced within minutes through competitive balance between the reaction rate and seed surface passivation using a strong binding ligand. The experimental results and theoretical simulations revealed a strong electromagnetic enhancement effect of the Au nanoisland arrays. Stable anticounterfeiting SERS labels were realized by stamping the nanoisland array-based ink on an ordinary paper, by which dyes of similar appearance can be easily discriminated.