cm5b03749_si_001.pdf (6.82 MB)
Oxidative Etching and Metal Overgrowth of Gold Nanorods within Mesoporous Silica Shells
journal contribution
posted on 2015-10-27, 00:00 authored by Tian-Song Deng, Jessi E. S. van
der Hoeven, Anil O. Yalcin, Henny
W. Zandbergen, Marijn A. van Huis, Alfons van BlaaderenComposite noble metal-based nanorods
for which the surface plasmon
resonances can be tuned by composition and geometry are highly interesting
for applications in biotechnology, imaging, sensing, optoelectronics,
photovoltaics, and catalysis. Here, we present an approach for the
oxidative etching and subsequent metal overgrowth of gold nanorods,
all taking place while the nanorods are embedded in mesoporous SiO2 shells (AuNRs@meso-SiO2). Heating of the AuNRs@meso-SiO2 in methanol with HCl resulted in reproducible oxidation of
the AuNRs by dissolved O2, specifically at the rod ends,
enabling precise control over the aspect ratio of the rods. The etched-AuNRs@meso-SiO2 were used as a template for the overgrowth of a second metal
(Ag, Pd, and Pt), yielding bimetallic, core–shell structured
nanorods. By varying the reaction rates of the metal deposition both
smooth core–shell structures or gold nanorods covered with
a dendritic overlayer could be made. This control over the morphology,
including metal composition, and thus the plasmonic properties of
the composite rods were measured experimentally and also confirmed
by Finite-Difference Time-Domain (FDTD) calculations. The presented
synthesis method gives great control over tuning over both plasmonic
properties and the particle stability/affinity for specific applications.