Plasmonic properties of an Ag@Ag2Mo2O7 hybrid nanostructure easily designed by solid-state photodeposition from very thin Ag2Mo2O7 nanowires

A new Ag@m-Ag2Mo2O7 plasmonic hybrid nanostructure was designed by an easy two-step synthesis method. Firstly, very thin photosensitive monoclinic m-Ag2Mo2O7 nanowires (NWs) were synthesized under ambient pressure and at low temperature by using Ag2Mo3O10·2H2O NWs as a pre-nanostucturated starting material. This innovative soft chemistry route offers some precise control over the purity, the structure and the nanostructuration of the m-Ag2Mo2O7 NWs that exhibit a very thin diameter of around 100 nm and a superior specific surface area compared to previously reported synthesis methods. Secondly, the plasmonic hybrid nanostructure Ag@m-Ag2Mo2O7 was easily in situ obtained via an all solid-state photodeposition method, by irradiating the m-Ag2Mo2O7 NWs under low energy and low-power UV-light. The composition, morphology and plasmonic properties of the nanocomposite were investigated by a combination of energy-dispersive X-ray spectroscopy, high-resolution scanning transmission electron microscopy, X-ray photoelectron spectroscopy and Auger spectroscopy, and near-infrared, Raman and UV-vis spectroscopies as well as spatially-resolved electron energy-loss spectroscopy. A plausible mechanism explaining the formation of the nano-heterostructure under irradiation was also discussed. The Ag@m-Ag2Mo2O7 nanostructure manifests interesting plasmonic properties particularly high surface-enhanced Raman scattering (SERS) sensitivity probed using 2,2′-bipyridine.