Hydrothermal synthesis of inorganic nanoparticles for potential technological applications : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatū, New Zealand
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Date
2021
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Massey University
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Abstract
Iron oxide nanoparticles (IONPs) are of interest in a diverse range of environmental and biomedical applications due to their intrinsic chemical, physical and thermal features such as superparamagnetism, high surface-to-volume ratios, high biocompatibility, low toxicity and easy magnetic separation. Many technological applications necessitate small (diameter < 20 nm) nanoparticles with narrow size distributions (< 5 %) and pronounced saturation magnetisation (Ms) for uniform physical and chemical effects. Historically, the synthesis of IONPs with controlled size and size distribution without particle agglomeration has proved challenging. In this thesis, we utilised an easy hydrothermal route and successfully synthesized two common phases of IONPs, namely Fe₃O₄ (magnetite) and α-Fe₂O₃ (hematite), using Fe(acac)₃ as iron source. By controlling the reaction conditions such as time, temperature, and the concentration of surfactants such as PVP and oleic acid, the different phases were selectively synthesized. The prepared nanoparticles were fully characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), energy dispersive X-Ray spectroscopy (EDS), atomic absorption spectroscopy (AAS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), vibrating-sample magnetometry (VSM), Brunauer-Emmett-Teller (BET) surface area measurements, photoluminescence (PL) and UV–Vis diffuse reflectance spectroscopy (UV–Vis/DRS). In Part I of this thesis, Fe₃O₄ and metal-doped spinel MxFe₃−xO₄ (M = Fe, Mg, Mn, Zn) nanoferrites were synthesised as agents for cancer treatment via a method called magnetic fluid hyperthermia (MFH). In Part II, α-Fe₂O₃ nanoparticles were hybridized with tin (II) sulfide (SnS) to create p-n heterojunction photocatalysts for efficient H2 production via ethanol photoreforming.
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Keywords
Iron oxides, Nanoparticles, Synthesis, Thermochemistry