Gold-diamond nanocomposite as a precursor for laser ablation synthesis of gold carbides
| Autoři | |
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| Rok publikování | 2013 |
| Druh | Další prezentace na konferencích |
| Fakulta / Pracoviště MU | |
| Citace | |
| Popis | The chemistry of gold nanoparticles (GNPs) represents fascinating interdisciplinary field of research with applications in physics, chemistry, nanotechnology, and medicine, especially. GNPs are also used for the synthesis of novel nano-structured materials such as nanocomposites with graphene, carbon nano-tubes and/or fullerenes. Nanodiamonds (NDs) show unique mechanical, thermal and electrical properties which make them promising molecular building blocks in nanotechnology. Because of their biocompatibility and non-toxicity [1], NDs are used as drug carriers and building blocks e.g., for the fabrication of tissue scaffolds and surgical implants, etc. Metal carbides are extensively applied in industry. For a long time it was believed that gold is not forming carbides. Matthew in 1900 reported for the first time gold carbide (Au2C2) [2]. The formation of gold carbides via laser ablation synthesis was preliminarily indicated in our laboratory [3, 4]. Nowadays, it is known that i) gold forms not only carbides but also aurides and ii) gold-carbon interaction is important for development of electronic devices. The aim of this work is to study the formation of gold carbides via laser ablation synthesis (LAS) using as a precursor a kind of nanocomposite of GNPs with NDs. The GNPs-NDs nanocomposite (Fig. 1 a) was prepared and characterized by atomic force and transmission electron microscopy, energy dispersive X-ray spectroscopy and mass spectrometry. Laser ablation synthesis of gold carbides (Fig. 2) was carried out by laser desorption ionisation time-of-flight mass spectrometry (LDI-TOF-MS). Example of mass spectrum indicating the formation of singly charged AumCn+ clusters is given in Fig. 1 b. Gold carbides AuCn+ (n = 1-11), Au2Cn+ (n = 1-16) and Au3Cn+ (n = 1-10) and also some gold aurides were observed. The structure of observed AumCn clusters most probably corresponds to gold carbides, but also endohedral supramolecular complex formation, e.g., Au@C10 is not excluded (Fig. 3) [5]. Such possibility was supported by modelling via semi-empirical approach using the HYPERCHEMTM program (release 5.1, 1998) from Hyper-cube Inc. (Gainesville, FL, USA). The confirmation of diamond doped structure with gold atom would mean the first experimental evidence of gold-doped NDs. Concluding, laser ablation of GNPs-NDs nanocomposite leads to synthesis of Au-C clusters. Stoichiometry of altogether 37 gold carbides was established while also some gold aurides were formed probably from partially hydrogenated NDs. It is suggested that some “gold carbides” might be gold-modified diamonds or gold-diamond endohedral complexes. Results concerning the synthesis via laser ablation might initiate development of new Au-C materials with specific properties. |
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