Study on selective oxidations of gold nanorod and mesoporous silica-coated gold nanorod

Abstract

The structural control-based manipulation of the anisotropic surface plasmon resonance (SPR) property of gold nanorod (AuNR) is significant and has wide application value in many fields. In this work, the quantitative studies of the ends-selective oxidations of AuNR and silica-coated AuNR using chloroauric acid as a oxidant were carried out. Results show that when the selective oxidation extent of AuNR was denoted by the aspect ratio changing rate, a linear relationship was displayed between this rate and the added amount of the oxidant, which suggested the Au(III)-induced selective oxidation of the nanoscaled Au(0) also proceeded stoichiometrically. In addition, different structural evolutions of silica coating layer that were determined to be caused by the different stabilities of the silica structure and described as the shape-adaptive change and the rigid state were found upon proceeding of oxidation. The study also showed that the structural change of the silica coating layer only had little influences on the mesopore size and its distribution state. These results should be valuable in better understanding the surface chemistry of AuNR and benefit the SPR variation-based and the silica coating-involved applications of AuNR.