Chemistry of carbonized metallic nanomaterials

Abstract

Magnetic nanomaterials have received significant attention because of their remarkable properties enabling applications in various fields such as catalysis, as contrast agents for magnetic resonance imaging, in sensing applications, as environmental catalysts and as adsorbents. Magnetic properties of materials depend on certain factors such as size, shape, crystallinity, composition, crystal structure, and synthetic methodology. Most of the pristine magnetic nanoparticles are highly pyrophoric in nature which poses difficulties in handling these materials. In addition, the ease of oxidation and potential toxicity of these materials preclude their practical applications. Further, these magnetic nanoparticles have strong magnetic interactions between them which leads to the aggregation of particles. These features affect the magnetic behaviour as well as the other characteristics of the material. In this context, fabricating magnetic nanomaterials with desired magnetic properties, chemical stability and surface chemistry is quite challenging. Similarly, plasmonic metal nanoparticles such as Ag and Cu also suffer from issues pertaining to oxidative instability upon air exposure under ambient conditions. Therefore, it is crucial to develop protection strategies to stabilize nanoparticles surface against oxidation. This thesis describes the synthesis of carbon encapsulated mono- and bi-metallic nanoparticles using solvated metal atom dispersion method in conjunction with digestive ripening approach followed by thermal annealing. The aim of the work is to understand the effect of size, shape, composition, and the nature of surface on the properties of these metallic nanomaterials. In this direction, nanosystems of Fe, Ag, Cu, Fe3C, and FeCo have been studied.