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

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 CdSxSe1-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.