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.
