Topotaxial Fabrication of Vertical AuxAg1-x Nanowire Arrays: Plasmon-Active in the Blue Region and Corrosion Resistant

Topotaxial growth of AuxAg1–x alloy nanowires (NWs) by postepitaxial deposition of Ag vapor on Au NWs and investigation of their plasmonic properties are reported. Ag vapor is supplied onto the epitaxially grown Au NWs, topotaxially turning them into AuxAg1–x alloy NWs. The original geometries and alignments of the Au nanostructures are well preserved, while the composition of the alloy NWs is controlled by varying the Ag vapor supply time. The Au0.5Ag0.5 NWs show high surface‐enhanced Raman scattering (SERS) activity comparable to that of Ag NWs as well as highly increased oxidation resistance. The plasmon‐active wavelength range of the Au0.5Ag0.5 NW is significantly extended to the blue region compared to Au NWs. The AuxAg1–x alloy NWs that have plasmonic activity in the blue region in addition to high corrosion resistance will make a superb material for practical plasmonic devices including SERS sensors and optical nanoantennas. Single‐crystalline AuxAg1–x nanowires (NWs) are synthesized by a topotaxial method using Ag vapor transport. Au0.5Ag0.5 NWs are more inert than Ag NWs to oxidation and have significant plasmonic activity in the blue wavelength region. They have strong surface‐ enhanced Raman scattering enhancement comparable to that of Ag NWs. The characteristics of Au0.5Ag0.5 NWs make them candidates for improved plasmonic devices.