Abstract | Over the years, various nanomaterials are continuously researched and synthesised to improve energy storage devices' energy and power densities. Two-Dimensional (2D) materials have developed great interest as a new prototype in materials science due to their collective advantages of ultrathin thickness and tuneable physical and chemical properties. The application of these nanomaterials extends to energy storage, water purification, catalysis, biosensors, antibacterial films, and coatings, thereby prompting the development of viable techniques for synthesising nanomaterials. However, challenges of further size reduction of nanomaterials with a simultaneous low cost, scalable and reproducible synthesis approach remain famous for sustainable progress in their practical applications. For the first time, 2D Graphene and MXene composite materials were synthesised through a Continuous Hydrothermal Flow Synthesis (CHFS) method and engineered into electrodes for electrochemical energy storage applications. CHFS is a single-step hydrothermal process involving mixing supercritical water (374 °C, 22.4 MPa) with a flow of water-soluble precursors in a reactor to obtain a rapid and controlled synthesis of nanomaterials. This synthesis method is scalable and tuneable by controlling process parameters such as flow rate, temperature, and pressure, thereby impacting the particle size, morphology, and crystal structure of nanoparticles. In addition, CHFS limits the use of toxic reagents and produces nanomaterials with desired properties in minimal time (seconds). One of the findings in this research paves way for the in-situ production and aqueous processing of functionalised MXene composites with a high electrochemical performance. Through aqueous dispersions as a green route of synthesis in CHFS, these 2D MXene and graphene derivatives were produced with enhanced electrochemical properties. This research provides a significant contribution to the expanding portfolio of continuous hydrothermal flow synthesis reactions. In this thesis, a variety of materials such as manganese (iv) oxide, manganese (iv) oxide/reduced graphene oxide (rGO), titanium (iv) oxide, titanium (iv) oxide/ reduced graphene oxide (rGO), and N-doped MXene/ titanium (iv) oxide, are hydrothermally synthesised via CHFS, developed and fabricated into electrode materials for energy storage applications. The in-depth analysis provides a comprehensive insight into how nanocomposites of promising energy storage properties are designable, made functional, and synthesised in-situ hydrothermally via CHFS from non-toxic and water-soluble precursors while delivering excellent electrochemical performance when used as electrodes in batteries. |
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