Tailoring the Surface Chemistry of Gold Nanorods through Au–C/Ag–C Covalent Bonds Using Aryl Diazonium Salts

Abstract

Tailoring the surface chemistry of gold nanorods is a key factor for successful applications in biology, catalysis, and sensing. Here, we report on the use of the diazonium salt chemistry for the functionalization of gold nanorods enabling the formation of strongly attached organic layers around the gold cores. The precise nature of the interface between the gold surface and the diazonium-derived aryl layers was probed by XPS, ToF-SIMS, SERS, and DFT. It was shown that the CTAB surfactant was partially exchanged by the diazonium salt which dediazonizes spontaneously to form Au–C covalent bonds with the surface. Interestingly, the silver used during the synthesis of gold nanorods and still present at their surface appears to be also involved in the grafting mechanism with Ag–C covalent bonds detected by ToF-SIMS. From this result, it is clear that the interfacial properties and reactivity of gold nanorods synthesized by the silver(I)-assisted seed mediated growth approach are strongly influenced by the presence of silver.