Sarcouncil Journal of Applied Sciences Aims & Scope

Abstract: Nanomaterials have become an important new class of advanced materials because their physicochemical properties can have significant differences from the properties of the corresponding bulk materials. These differences may arise due to their unique features namely nanoscale dimensions, high specific surface area, quantum-size effects, surface energy and size-dependent structural effects. Nanomaterials are being used in catalysis, electronics, energy conversion and storage, environmental control, sensing, medicine and biotechnology. Materials in the nano regime can exhibit significant enhancement in certain properties and it is a fundamental requirement that these properties can be accurately predicted and controlled which in turn requires fine control of the physical and chemical properties of the materials concerned. As the performance of a nanomaterial is critically influenced by its composition, size, morphology, crystallinity, surface properties and degree of aggregation, the controlled preparation and thorough characterization of nanomaterials are vital. This review considers the main methods available for the preparation of nanomaterials with particular emphasis on top-down and bottom-up approaches. Physical techniques (including ball milling, laser ablation, sputtering and laser ablation, lithography) and chemical techniques (including sol-gel, precipitation, hydrothermal/solvothermal syntheses, chemical vapour deposition and microemulsion methods), along with biological or environmentally friendly preparation routes are summarized. A broad discussion of the main methods used to characterize nanomaterials including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS), Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDS) and Brunauer-Emmett-Teller (BET) analysis as well as the relationship between preparation conditions and measurable structural and surface properties are presented. The question of reproducibility, agglomeration, scale-up, environmental impact and the complementary nature of different techniques are then considered.