| AVS 63rd International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS2+AS+HC+NS-TuM |
| Session: | Nanostructures: Growth, Reactivity, and Catalysis |
| Presenter: | Waqqar Ahmed, COMSATS Institute of Information Technology, Pakistan |
| Authors: | W. Ahmed, COMSATS Institute of Information Technology, Pakistan J.M. van Ruitenbeek, Leiden University, Netherlands |
| Correspondent: | Click to Email |
Gold nanoparticles exhibit interesting optical properties because of the surface plasmon resonance. The shape and size of gold nanoparticles can markedly influence their optical properties. A spherical nanoparticle has a single palsmon peak, while rod-shaped nanoparticles have two plasmon peaks because of their shape anisotropy. Furthermore, slight deviations from the rod morphology can markedly influence the optical properties. For example, worm-shaped gold nanoparticles can have more than two plasmon peaks. Moreover, nanoworms can display very high local field enhancements upon plasmon excitation owing to their special shape and surface roughness.
We have devised a simple, seedless, high-yield protocol for the synthesis of gold nanoworms [1]. Nanoworms were grown simply by reducing HAuCl4 with ascorbic acid in a high pH reaction medium in the presence of growth directional agents. In contrast to the seed-mediated growth of gold nanorods where a seed particle grows into a nanorod, nanoworms grew by oriental attachment of nanoparticles. By varying different reaction parameters we were able to control the length of NWs from a few nanometers to micrometers. Furthermore, the aspect ratio can also be tuned over a wide range.
Owing to their special morphology, gold nanoworms are much superior than the conventional nanorods for numerous applications. For instance, we have seen that they show markedly superior SERS and catalytic properties compared to their nanorod counterparts. This is due to their high-energy rough surface and twisted shape, which not only provides an ideal platform for catalytic activities but also generates local hot-spots upon plasmon excitation. Our study shows that both catalytic and SERS properties of gold nanoworms are strongly dependent on their length.
[1] W. Ahmed, C. Glass, and J.M. van Ruitenbeek, Nanoscale, 6, 13222, (2014)