High-sensitivity refractive index of Au@Cu2−xS core–shell nanorods

A high refractive index sensitivity of Au@Cu2-xS core-shell nanorods working in the near-infrared is theoretically demonstrated. The sensitivity of our sensor reaches 1200 nm per Refractive Index Unit (RIU), which is higher than that of other metal-metal core-shell nanorods. The reason is that the new materials and structure of Au@Cu2-xS core-shell nanorods lead to a unique sensing principle. It is noteworthy that the refractive index (RI) sensitivity is more susceptible to the effects of the shell-thickness to core-radius ratio than to the aspect ratio. These results show that the excellent sensitivity performance of Au@Cu2-xS core-shell nanorods working in the near-infrared can be treated as a new tool to detect the minute variations in refractive index for small amounts of chemicals and biomolecules.