Abstract
The discovery of graphene marked a pivotal moment in the research and development of two-dimensional (2D) materials, igniting extensive exploration beyond the confines of graphene. Most 2D materials are derived from the exfoliation of 3D bulk materials held together by weak van der Waals (vdW) forces. However, the stringent reliance on vdW interactions limits the diversity of available 2D materials, necessitating the exploration of alternative materials. Consequently, the synthesis of nanoplatelets from non-van der Waals (n-vdW) crystals is gaining prominence.
Nevertheless, the current synthesis methods for 2D nanomaterials from n-vdW require rigorous conditions and substantial energy consumption. Hence, there is a pressing need for innovative and efficient synthesis techniques. Furthermore, 2D nanomaterials from n-vdW hold tremendous potential in specific applications, owing to their adjustable properties such as surface morphology, electronic structure, and chemical reactivity.
This thesis centers on the synthesis of 2D nanoplatelets from n-vdW crystals and demonstrates their practical utility. The research aims to unveil the synthesis of 2D nanoplatelets from two n-vdW crystals: (1) Muscovite mica and (2) MgO/Mg. The focus commences with the synthesis of 2D Muscovite mica, employing a top-down approach, separating layers (exfoliating) from 3D bulk mica to achieve 2D mica nanoplatelets (MNs) and its composites, specifically the 2D Ga/mica nanoplatelet composite (Ga/mica_Ns). The exploration then proceeds to the synthesis of 2D KAlSiO4 nanoplatelets (KAlSiO4_Ns), utilizing a top-down and bottom-up combination, involving dehydration, degradation, and recrystallization. The journey culminates in the synthesis of 2D Mg(OH)2 nanoplatelets-based composites, employing a bottom-up approach, that begins with the surface hydration of 3D MgO/Mg to attain 2D Mg(OH)2-based composite nanoplatelets (Mg(OH)2_Ns).
The findings contribute to the creation of a novel model utilizing Density Functional Theory and biaxial theory, offering insights to predict the efficiency of intercalants in the n-vdW exfoliation process before conducting experiments. Mica nanoplatelets were successfully exfoliated using two top-down methods: Liquid Phase Exfoliation (LPE) and Liquid Metal Embrittlement (LME). Furthermore, inherent techniques from liquid phase exfoliation, including microwave solvothermal treatment in a high pH solvent and salt mixture, and sonication, were employed to transform 3D bulk mica into 2D KAlSiO4.
The surface of MgO/Mg crystals was subjected to steam treatment using a customized closed-loop steam system, proven to be environmentally friendly, cost-effective, and safe. Furthermore, these nanoplatelets demonstrated their applicability in various sustainable applications, including CO2 capture, dye degradation, wastewater treatment, solar thermal conversion, white light design phosphor materials, and sustainable black coatings.
To conclude, this thesis emphasizes an innovative approach to synthesizing two-dimensional nanoplatelets from Muscovite mica and MgO/Mg n-vdW crystals. The applications of these nanoplatelets were explored for diverse sustainable technological advancements.