Controlled Etching of Gold Nanorods Within Mesoporous Silica Shells at Mild Conditions

Abstract Surface plasmon resonance of precious metal gold nanorods can be tuned by controlling the aspect ratio, and they find widespread applications in biotechnology, imaging, sensing, optoelectronics, photonics, and catalysis. Here, a method is proposed for the controlled etching of gold nanorods within mesoporous silica shells by using a certain concentration of H 2 O 2 at room temperature. In the experiments, the amount of HCl is varied to adjust the acidity and/or change the amount of H 2 O 2 to control the speed of corrosion, achieving controllable adjustment of the aspect ratio of the gold nanorods. The extinction spectra show that under the action of H 2 O 2 and HCl, the longitudinal plasmonic resonance of the gold nanorods shifted to shorter wavelengths, and the intensity of the longitudinal plasmonic resonance decreased. The more hydrochloric acid or hydrogen peroxide added, the faster the corrosion rate of the gold nanorods, and the faster the blue shift of the longitudinal plasmonic resonance. In addition, the intensity of the extinction spectra at 320 nm increased linearly versus time, which can also be used to monitor the etching process. By corroding gold nanorods to control the plasmonic resonances, gold nanorods can find broader applications.