Gold nanoparticle integrated with nanostructured carbon and quantum dots: synthesis and optical properties

Yuan Li,Nitin Chopra

doi:10.1007/s13404-015-0163-3

Abstract

Multilayer graphene shell encapsulated gold nanoparticle—quantum dot hybrids were derived by combining wet-chemical, thermal, and covalent chemistry approaches. Uniformly patterned gold nanoparticles on a silicon substrate were obtained via gold film deposition in an electroless method followed by a thermal dewetting process. The resulting gold nanoparticles were further surface oxidized and utilized as catalysts for the chemical vapor deposition growth of multilayer graphene shell encapsulated on the gold nanoparticles (referred as “multilayer graphene shell encapsulated Au nanoparticle” or graphene nanoparticles (GNPs)). As a next step, the surface of GNPs was modified to result in carboxylic (−COOH) functionalities, which enabled carbodiimide-based covalent linking of amine-terminated CdS x Se1-x @ZnS quantum dots (QDs) on the GNP surface. The GNPs and GNP-QD heterostructures were characterized using scanning and transmission electron microscopy for size, morphology, spatial distribution, and crystal structure evaluation. In addition, UV-vis, fluorescence spectroscopy, and discrete dipole approximation (DDA) modeling were utilized for understanding the band gap energies, fluorescence quenching, and light-matter interactions of the derived hybrids/heterostructures.

Highlights

The surface modification of photonic nanostructures such as gold (Au) nanoparticles can lead to novel physical phenomena including selective light-matter interactions and rapid energy transfer processes [1,2,3]
We report an approach for the controlled patterning of multilayer graphene-modified Au nanoparticles on a silicon substrate and covalent linking of graphene shell around Au nanoparticles (GNPs) with semiconducting CdSxSe1-x@ZnS quantum dots
The presence of encapsulating multilayer graphene shell around Au nanoparticles enhanced the surface chemistry of the GNPs and allowed their linking with quantum dots in a simple carbodiimide functionalization approach

Summary

Introduction

The surface modification of photonic nanostructures such as gold (Au) nanoparticles can lead to novel physical phenomena including selective light-matter interactions and rapid energy transfer processes [1,2,3]. The challenge is to achieve stable coating around Au nanoparticles, which prevents the exposure of Au nanoparticles to unwanted solution environment, prevent their aggregation, and yet retain their properties [4,5,6] Overcoming this challenge will enable conservative utilization of Au nanoparticles in photonic applications. A promising approach is to encapsulate Au nanoparticles in a sub-5-nm-thin carbon or graphene shell Such modification of Au nanoparticles can lead to hierarchical heterostructures by utilizing rich carbon chemistry. The carbon component can influence the light-matter interactions for such hybrid systems, for example, by reducing scattering effects [10] Such hybrid systems can be envisioned as a new kind of metamaterial architectures

Methods

Results

Conclusion