Au Hierarchical Micro/Nanotower Arrays and Their Improved SERS Effect by Ag Nanoparticle Decoration

Arrays of Au hierarchical micro/nanotowers have been achieved on Au-coated silicon planar substrate, via electrochemical deposition in a mixed aqueous solution of PVP and HAuCl4 under appropriate electrodeposition conditions. The Au hierarchical micro/nanotower arrays have exhibited distinct surface-enhanced Raman scattering (SERS) effect due to the enhanced local electromagnetic field in the vicinity of the sharp nanotips of the towers and the gaps between the neighboring nanotowers. More importantly, the SERS effect has been further improved significantly via decorating Ag nanoparticles on the surfaces of the Au hierarchical micro/nanotowers due to the Ag nanoparticle hot spots themselves and the hot spots formed at the interfaces between the Ag nanoparticles and the Au micro/nanotowers. These Ag-nanoparticle-decorated Au hierarchical micro/nanotower arrays have shown potential applications as sensitive and robust SERS substrates in monitoring environmental pollutants, such as 3,3',4,4'-tetrachlorobiphenyl (PCB-77).