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In the past decade, Zeolitic imidazolate frameworks (ZIFs) as precursors towards functional materials have attracted enormous attention. The easy modification of the ZIF structure itself, as well as the easy incorporation of various materials by different manners to form ZIF-based composites, have resulted in a great kingdom of functionalised ZIFs. Moreover, functional ZIFs derived nanocomposites of desired compositions and sophisticated structures can be obtained under suitable pyrolysis conditions and show great potential in various catalytic applications. Built on a pertinent literature review with special emphasis on the application in electrocatalytic water splitting, this thesis focuses on the rational design, synthesis, characterisation and electrochemical evaluation of ZIF-based composites and their nanocomposite derivatives. First, a facile and cost-effective one-pot in situ encapsulation method was applied for the synthesis of phosphotungstic acid (PTA) encapsulated ZIF-67, and the bimetallic WS2/Co1-xS/N, S co-doped porous carbon nanocomposites were derived from one-step sulphurization/carbonisation of the PTA@ZIF-67 composites. Significant improvement in electrocatalytic activity towards both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) was observed. Then, a different post-synthetic strategy to introduce PTA into ZIF-67 is utilised. Moreover, phosphomolybdic acid (PMA), which is unable to be introduced into ZIF-67 with the previous in situ encapsulation method, has been successfully encapsulated into modified ZIF-67 with this new synthesis approach. The HER and OER active, defect-rich ultra-fine Co-Mo-S/N, S-doped porous carbon nanocomposites and WS2/Co1-xS/N, S co-doped porous carbon nanocomposites were derived from the modified ZIFs. This new synthesis strategy to modify acid-sensitive ZIFs with selected compounds offers an alternative approach to develop novel transition metal sulphide/carbon composites for various applications. Finally, the in situ encapsulation method is extended to a metal organic framework (MOF)-based composites (PMA@MIL-100), which demonstrates the universal applicability of the method. Bimetallic Fe-Mo sulphide/S-doped carbon nanocomposite was derived from the PMA@MIL-100 composite through chemical vapour sulphurization at high temperatures and showed a dramatic improvement in the HER performance.

In mammals, hair cell loss due to acoustic over‐stimulation, ototoxic drugs, ageing, and genetic defects is irreversible, leading to a permanent loss of function. Any loss occurred in cochlea hair cells can lead to an unavoidable loss in hearing. Tiny nerves called 'hair cells' are hit with sound so hard that the hair cells are bent, broken, and sometimes sheared off. Hair cells in the cochlea are not capable of regenerating themselves. Dissimilar to skin, hair and other cells in the body, once cochlear damage happens, no "growing" is available. The natural hair cell includes pillars in different heights which are connected with tip-links on top. The main role of hair cells is the conversion of acoustic signal to electrical ones which is exactly the piezoelectric materials functionality performance. For the purpose of mimicking the artificial hair cell like sensors like a prototype, this research fabricated and tested an acoustic prototype device including two main parts. The base part is required be flexible and stable. On top of the based structure, there must be a thin sheet of piezoelectric structure capable of mimicking the tip-links role. Firstly, this thesis presents how to fabricate a semi-permanent designed negative photoresist SU-8 mould to work as a template for peeling up the cured and formed Polydimethylsiloxane (PDMS) pillars in microscale. Secondly, to get the same function of tip-links in the hair cells, Polyvinylidene fluoride (PVDF) nanofibers are fabricated which is an important part of the main hair cell structure. Thirdly, electrospinning is applied to achieve piezoelectric electrospun nanofibers. Fourthly, the behavior of 5 different additives by reason of their biocompatibility and possibility of presenting different properties on the produced PVDF composites will be evaluated. Finally, the thesis will evaluate the prototype performance based on acoustic sensing experiments. The main findings are as follows: • Successfully synthesized a semi-permanent SU-8 molud in microscale using UV-lithography and achieved a triangular mould including 4 rows of exposed holes at different depths. A series of preparations steps is needed following up the fabrication processes to get the best geometrical structure of the semi-permanent SU-8 mould. • The fabrication of PDMS pillars of different heights starting from 100 µm for the first row to 400 µm in the fourth row with an increment of 100 µm and the diameter of almost 50 µm for each single pillar was done. The PDMS solution contains two agents a 10:1 mixture of PDMS elastomer (Sylgard 184) to cross-linker which is combined and mixed well. • Conducted electrospinning method to achieve the phase transition of PVDF material from α and γ phases to β-phase due to the mechanically drawing fabrication process. The pure PVDF powder is compared with pure electrospun PVDF nanofibers in different concentrations for their crystal structures and phase change behavior. For the group of pure PVDF electrospun nanofibers, the comparison includes further investigation into piezoelectricity and triboelectric properties by use of PFM and a linear acoustic actuator as well as morphology and structure analysis including SEM, TEM, XRD, FTIR, XPS, DSC and Raman spectroscopy. • By use of electrospinning method, we have identified that changing the concentration of PVDF powder from 1.50 to1.80 g with an increment of 0.15 into the mixture of DMF (Dimethylformamide) /Acetone (3/7) volume ratio of solution plays an effective role in the content of β-phase, leading to the change of piezoelectricity and triboelectric properties. Moreover, the thinnest mean diameter of electrospun fibers allocates to the sample with highest value of open circuit voltage (170 mV) which is equal to 213 nm. A layer of 0.015 mm thick of such sample with the highest β-phase content has generated the highest output voltage and current values of 124 V and 174 nA, respectively. • To evaluate the piezoelectricity properties for the current PVDF electrospun fibers in response to various additives, CNTs, LiCl, TiO2, WO3 and ZnO particles in different size have been added to the prepared solution separately. The piezoelectric properties depend on the highest β-phase content reached in each sample. When the additives are WO3, ZnO and CNTs, they achieved a uniform dispersion within the fibers that exhibiting a mean diameter around 150, 780 and 970 nm, respectively. However, both TiO2 and LiCl acted differently from other additives on the morphology, piezoelectric and triboelectric properties, leading to thicker fibers and negative impact on the β-phase formation. • Successfully produced hybrid samples including additives have been investigated thoroughly. For TENG/PENG devices in sound energy harvesting evaluation of pure PVDF electrospun fibers and the incorporation of additives into the PVDF solution, an acoustic sensing measurement is applied. Among all of samples, the device with WO3 electrospun nanofibers shows highest values of output amongst all composites tested, being 2.12 mV at a frequency of approximately 6 kHz. For the artificial device including the pure PVDF electrospun nanofibers on top and PDMS pillars as the based part, the application of cell cultures including the HCT-116 (human colon cancer) and HEK-293 (embryonic kidney) approved that they continued to grow around the device and no sign of toxicity was evident.

Silicon carbide (SiC) as a type of ceramic material possesses unique properties such as high hardness, good high temperature strength, and excellent oxidation resistance. However, the intrinsic shortcomings of ceramic-based materials, such as high brittleness, low recoverable compressibility, and low fatigue resistance, prevent their utilisations as structural or functional components. To overcome these issues, highly porous lightweight and flexible SiC ceramics constructed by nanowires are promising alternatives for advanced engineering applications. The aim of this thesis is therefore to fabricate highly porous lightweight and flexible SiC nanowire structures by three novel approaches: (1) in-situ chemical-blowing; (2) melamine foam-based replica template; (3) electrospinning and explore their properties towards different applications. The overview, including the aims and objectives of this thesis is outlined in Chapter 1. The existing knowledge about lightweight SiCNW structures including crystallography, synthesis approaches, physical properties (mechanical strength, thermal conductivity, high temperature stability), and well-developed energy and environment-related applications (piezoresistive sensors, catalyst support, absorbers, and filters) is documented in Chapter 2. The generic information of the starting materials, synthesis techniques, equipment, and method used for the fabrication of 3D SiCNW structures, characterisation of their microstructural features, and evaluation of the various aspects of their multifunctionalities is descripted in Chapter 3. To identify suitable techniques to assemble SiC nanowires (SiCNWs) into 3D architectures, Chapter 4 provides a selection of advanced manufacturing approaches for lightweight SiCNW structures with easy and precise control of the overall shape and growth of SiCNWs. Followed with the demonstration of the exciting properties of the as-obtained three SiCNW structures including mechanical properties, thermal insulation performance, thermo-oxidation resistance, and fire-retardance in Chapter 5. Finally, based on their own characteristics, the applications of the SiCNW structures such as piezoresistive sensors, catalyst support, and efficient absorbents for oil and organic solvents are present in Chapter 6. A guidance in the manufacturing of advanced ceramic nanowire structures with desired microstructures and properties tailored for specific applications will be eventually provided. I first demonstrated the creation of SiCNW sponges by a facile template/catalyst-free sugar-blowing technique, by reacting SiO2 with sustainable kitchen sugar, using NH4Cl as a blowing agent. The as-grown, highly porous SiCNW sponges exhibited a core-shell structure, the core part with a density of 115-125 mg cm-3 was comprised of short and tangled SiC whiskers with SiC flakes embedded, while the shell layer with an ultralow density of ~25 mg cm-3 consisted of numerous smooth SiCNWs. These sponges exhibited a compressive modulus of ~389 kPa, recoverability under cyclic compression loading for 100 cycles at a strain of 20% and a thermal conductivity of 42-92 mW m-1K-1. Secondly, I reported the fabrication of SiCNW scaffolds with tuneable microstructures, densities, and therefore properties, by regulating the solid loading content in the reticulated melamine foam (MF) template. The resulting samples exhibited high strength (modulus up to ~167.3 kPa), good recoverability (11% residual strain and 72% maximum stress after 100 compressive cycles at a ε = 20%), and low thermal conductivity of 32-54 mW m-1K-1. Finally, I successfully created 3D SiCNW aerogels by using a Mille crêpe stacking and sintering of the electrospun PAN/SiO2 fibres for the first time. The resulting aerogels made of interconnected SiCNWs displayed an ultralight density of 29 mg cm-3, excellent compressive recoverability and fatigue resistance. Meanwhile, the SiCNW aerogels exhibited a thermal conductivity of 24 mW m-1K-1, even lower than that of the air, suggesting its superinsulation capability. Benefitting from intrinsic properties of SiC, experimental results have shown that all the as-obtained SiCNW structures exhibited good thermal insulation performance, exceptional high-temperature stability, fire-retardance, and temperature-invariant elasticity. Furthermore, I have explored the best-suited functional applications for each SiCNW structure. The SiCNW sponges and aerogels with better compressive recoverability and mechanical stability exhibited interesting electromechanical sensing capability. The sponge-based sensor exhibited a gauge factor up to 87 and stable wide-range compression-resistance responses. Whilst the aerogel-based strain sensor with higher recoverable strains presented stable sensing behaviour at different strains, frequencies, elevated temperatures over 200 °C and excellent repeatability over 2000 cycles. Owing to the cellular structure with the co-existence of SiC nanowires and struts, good interconnectivity, and competent mechanical strength and stability, the SiCNW scaffolds demonstrated the exclusive suitability as excellent support for MOF-derived TiO2-C catalyst, with ~35% enhanced in-situ loading of the catalyst, enabling a superior photocatalytic performance and good repeatability for at least 3 cycles. I further examined the SiCNW structures as organic solvent/oil absorbent. They exhibited rapid absorption of various organic solvents and oils. Typically, the SiCNW aerogels possess the highest absorption capacity of 32-86 g g-1, as well as robust recoverability. Meanwhile, the absorbed content can be easily removed by squeezing, distillation, and combustion, while the SiCNW structures remain unchanged. These features have shown that the SiCNW structures are promising for applications for the potential removal of chemical spills and oil leakage, with the advantage of easy recycling. All these remarkable findings will not only provide an important opportunity to advance the understanding of lightweight SiCNWs structures and make original contributions to utilise them as multifunctional devices, but also bring us the new ways to reshape the manufacturing of porous ceramics for future energy and environment-related applications.

Nanomedicine utilises biocompatible nanomaterials for therapeutic as well as imaging purposes, for the treatment of various diseases including cancer, neurological disorders and wound infections. Graphene, a material composed of a single layer of carbon atoms, has recently shown great potential to improve diagnostics and therapeutics, owing to its small size, large surface-area-to-volume ratio and unique physicochemical properties. However, the limited fabrication, in vitro and in vivo functionalities published in the literature indicate inconsistencies regarding the factors affecting metabolic fate, biodistribution as well as toxicity patterns of graphene. This thesis focuses on the biological effects of graphene-based materials, including graphene oxide (GO), reduced graphene oxide (rGO), graphene nanopores (GNPs), graphene quantum dots (GQDs) and three-dimensional graphene foam (GF). These can be used to closely mimic therapeutic functions and thereby open up new pathways to anticancer nanomedicine. In this work, a biocompatible GO-based anti-metastatic enzyme cancer therapy approach has been introduced for the first time to target the extracellular pro-metastatic and pro- tumourigenic enzymes of cathepsin D and cathepsin L, which are typically overexpressed in ovarian and breast cancers. Definitive binding and modulation of cathepsin- D and -L with GO has revealed that both of the enzymes were adsorbed onto the surface of GO through its cationic and hydrophilic residues under the biologically relevant condition of acidic pH. It has been demonstrated that low concentrations of rGO were shown to significantly produce late apoptosis and necrosis rather than early apoptotic events in lung cancer cells (A549 and SKMES-1), suggesting that it was able to disintegrate the cellular membranes in a dose-dependent manner. GNPs at lower concentrations (250μg/ml) induce upregulation of phosphatidylserine on cell surface membrane (i.e. early apoptotic event), which does not significantly disintegrate the cell membrane in the aforementioned lung cancer cells, while higher concentrations of GNPs (5 and 15 mg/kg) in rats (when intraperitoneally injected) exhibited sub-chronic toxicity in a period of 27 days. The interaction of GQDs and trypsin has revealed the strong bonding capacity of GQDs with trypsin, owing to their surface charge and surface functionalities evidencing the high bioavailability of GQDs in enzyme engineering. Finally, 3D GF was developed to probe the role of graphene-based scaffold cues in the field of regenerative medicine revealing their cell attachment to in vitro cell cultures. Furthermore, GF was shown to maintain remarkable biocompatibility with in vitro and in vivo toxicity screening models when exposed for 7 days at doses of 5, 10 and 15 mg/l. Taken together, graphene and its modified structures developed in this thesis promise to revolutionise clinical settings across the board in nanomedicine which include, but are not limited to, ultra-high sensitive enzyme adsorbents, high throughput biosensors, enzyme modulators and smart scaffolds for tissue regeneration.

Shrinking down into nanoscale, materials exhibit huge property advantages over their bulk form. New forms of carbon at nanoscale have occupied the prominent position in modern materials research. With a very long history accompanying our human civilisation, carbon as a wonder material has once again contributed to our technological advances, as evidenced by the discoveries and research attractions in the last a few decades. Research into fullerenes (C60, C70, etc.), carbon nanotubes (CNTs) and graphene has been continued raising, because of the numerous novel properties associated with these new carbon forms1-3. On top of their excellent electronical, physical and chemical properties, CNTs and graphene also exhibit excellent mechanical properties including ultra-high tensile strength, Young’s Modulus, as well as high thermal conductivities. Research into carbon has also promoted the flourish of many new non-carbon nanomaterials, and typical examples include the inorganic fullerene-like tungsten disulphide (IF-WS2) nanoparticles (NPs), numerous oxide NPs and nanowires that also exhibit various remarkable properties, such as high hardness and anti-oxidation stability. To combine the outstanding performances of both carbon and non-carbon nanomaterials by marrying nanoscale carbon with various metal oxide particles, which forms the backbone of my thesis by carrying out the intensive investigations. In my project it have further validated the advantages of the resulting new carbon-coated NPs in different polymeric matrix composites. The main findings are as follows: 1. A home-made rotary chemical vapour deposit (RCVD) system has been modified and this versatile facility has been applied successfully to produce different types of graphitic carbon-coated nanocomposite particles, from micro- down to nano-scale, including IF-WS2, TiO2, ZnO, Y2O3, Cr2O3, CeO2 and ZrO2 etc. The production can be up to 30 g/per batch, which is 10s times more than using a traditional static furnace, by avoiding severe agglomeration. 2. The resulting coating consists of a few layered graphitic carbon with lattice space 0.34 nm. The thickness of the coating is simply controllable between 1-5 nm, depending on the deposition time (10~60 min), precursor injection flow rate (1.2~2.4 ml/L) and heating temperature (700~900 oC). Furthermore, the oxide core of ZnO@C was removed by heating under the H2/Ar atmosphere, and have successfully generated nano- to micro-scale, hollow, closed, and all-carbon structures. 3. The commercial Nylon 12 is applied to fabricate the metal oxide polymer composite. Using ZnO@C-Nylon 12 composite as an example, at 2 wt% content, the composites have achieved with the ultimate tensile strength increased by 27% (from 47.9 to 59.6 MPa), In particular, at 4 wt% content, the ZnO@C showed an impressive improvement in thermal conductivity of nearly 50% (From 0.21 t0 0.31 W∙m-1∙K-1), comparing 16% improvement for ZnO-Nylon 12 composite. 4. Apart from investigations of nylon composite, intensive studies of the Poly ether ether ketone (PEEK), an important high performance engineering thermoplastics polymer, and its nanocomposites reinforced by IF-WS2 and IF-WS2@C have been carried out in this thesis. The IF-WS2/PEEK composites exhibited not only an improvements of 24% (From 77.6 to 96.7 MPa) in the tensile strength (2 wt%), but also showed an extraordinary increase in thermal conductivity by 190%, from 0.248 to 0.719 W∙m-1∙K-1 at 8 wt%, higher onset decomposing temperatures (54 oC) against the plain PEEK. 5. Moreover, owing to the better dispersal capacity of IF-WS2@C NPs, the ternary IF-WS2@C-PEEK nanocomposites produced in this thesis displayed impressive mechanical properties, increased by 51% (From 77.6 to 120.9 MPa, at 2 wt%), and extremely greater thermal conductivity, with 235% (From 0.248 to 0.831 W∙m-1∙K-1 at 8 wt%), and better stability than the comparison IF-WS2-PEEK composites. The parameters influencing the coating quality and thickness have also been investigated. Further, their interface studies based on the FTIR and XPS techniques have verified the formation of chemical bonding (C=S bonding and carbon π-π bonding), rather than physically bonded together. The successful application of the generic RCVD process can be further extended to the processing of many new particles for an ultrathin carbon coating. Considering the vast amount of literature focusing on carbon, the project further processing of carbon-coated materials in composites could easily be tailored to achieve desired surface contacts with different matrices and leading to the better desired performance, as verified in this thesis for the advanced binary and ternary composites. Finally, this research is expecting to expand the application potentials of PEEK-based nanocomposites in critical areas where thermal conductivity and thermal stability are important.

Zeolitic imidazolate frameworks (ZIFs) represent a new and special class of metal organic frameworks comprised of imidazolate linkers and metal ions, with structures similar to conventional aluminosilicate zeolites. Their intrinsic porous characteristics, abundant functionalities as well as exceptional thermal and chemical stabilities, have led to a wide range of potential applications for various ZIF materials. Explosive research activities ranging from synthesis approaches to attractive applications of ZIFs have emerged in this rapidly developing field in the past 5 years. Moreover, ZIF materials act as outstanding templates or precursors to produce porous carbons and related nanostructured functional materials based on their high surface area, controllable structures and rich metal/organic species in their scaffolds. In this thesis, the synthesis and applications of ZIFs and their related nanostructured functional derivatives are demonstrated with special emphases on the applications in energy storage and conversion areas. In brief, this thesis presents the following research findings: 1). A cost-effective and facile preparation method for the synthesis of zeolitic imidazolate framework-8 (ZIF-8) material has been developed. ZIF-8 can be obtained from stoichiometric precursors in aqueous ammonia solution without any other additives at room temperature. The structures, particle sizes and textural properties of the resulting ZIF-8 materials can be controlled by the concentration of aqueous ammonia. In addition, the formation of ZIF-8 can be remarkably affected by different types of anions. The anion effect capacity is revealed to be SO42- > CH3COO- > Cl- > Br- > NO3-, which follows the classic Hofmeister anion sequence. 2). Composites containing ZIF-8 and various contents of graphene oxide (GO) have been successfully prepared for the first time by using an in-situ method in aqueous ammonia solution. Different material characterization techniques confirm the formation of strong interactions between ZIF-8 and GO in the resulting composites. The crystal sizes and the textural properties of the synthesized composites can be modulated by control of the added amount of GO. Interestingly, the in-situ synthesized composites exhibit enhanced CO2 adsorption energy and significant CO2 storage capacity. A mechanism has been proposed accordingly to the strong interactions and the synergistic effect between ZIF-8 and GO. 3). Apart from the investigation of ZIFs themselves, exploration of ZIF derivatives has been carried out in this thesis. Homogeneously-dispersed ZnO nano-particles embedded within N-doped porous carbon matrix using ZIF-8 as a template and precursor have been successfully synthesized by a simple one-step water steam carbonization route. The as-synthesized ZnO/C-S-S and ZnO/C-S-L exhibit high CO2 uptake capacities, CO2 selectivity, and CO2 adsorption energy. The mechanism of enhanced CO2 adsorption energy has been proposed and discussed. Moreover, because of excellent adsorption and degradation abilities, these ZnO/C-S-S and ZnO/C-S-L composites are highly efficient for methylene blue (MB) removal from wastewater under visible-light irradiation. Kinetics studies of MB removal show that the adsorption process is dominated by a pseudo-second-order adsorption model. 4). In addition, ZIF-67 derivatives ranging from cobalt-embedded porous N-doped carbon/carbon nanotubes to hollow carbon nano-onions under different carbonization temperatures have been prepared. The carbonization temperature effects on the morphology and electrocatalytic properties of resultants are well studied. An optimum carbonization temperature at 800 oC for electrocatalytic performance was proposed within the range 600-2000 oC. Due to the hierarchical porous carbon structure, N-doping effect and the homogeneous cobalt dispersion, the as-synthesized sample Co@C-800 nanocomposite exhibits excellent catalytic activities for both Oxygen reduction reaction (ORR) and Oxygen evolution reaction (OER) with good stability. 5). Further development of the other ZIF-67 derivatives has been investigated. Homogeneously dispersed cobalt sulfide/N, S co-doped porous carbon nanocomposites and nickel promoted cobalt sulfides/N, S co-doped porous carbon have been successfully prepared by a simple and efficient method via the simultaneous carbonization and sulfurization using ZIF-67 and Ni-substituted ZIF-67 as a precursor and template, respectively. Due to the hierarchical porous carbon structure, N, S co-doping effect and the homogeneous nanoparticle dispersion, the as-synthesized nanocomposites exhibit excellent catalytic activities for both ORR and Oxygen evolution reaction OER with good stability.

WS2, MoS2 and ZrS2 nanomaterials in various forms, such as nanoflakes, inorganic fullerene-like nanoparticles and nanorattles, were synthesised using two modified conventional techniques: solid-gas reaction and chemical vapour deposition. Both of these techniques are essentially based on reactions between metal oxides/chlorides and sulphur at a relatively low temperature in the range of 350-950°C in H2/Ar. Compared with other common techniques, these techniques are cost effective and environmentally friendly and produce well-crystallised WS2, MoS2 and ZrS2 nanomaterials with controllable sizes and morphologies, arising from the involvement of simple equipment and a H2S-free process. With the solid-gas reaction technique, the formation of WS2 and MoS2 inorganic fullerene like (IF) particles follows a so-called "template growth" mechanism, which implies that the sizes of the final products resemble their metal oxide raw materials. Therefore, because of the usage of WO3 nanoparticles and MoO3 submicron particles as precursors, nanosized WS2 (<100 nm) and submicron-sized MoS2 (approximately 500 nm) particles were generated, respectively. Further investigation of the reaction mechanism reveals that H2 is a vital factor in the formation of WS2 IF nanoparticles. Without H2, WS2 nanoflakes are instead produced, which is attributed to that the formation of WS2 IF nanoparticles based on the synergy between H2 reduction and S sulphidation. Using the CVD technique, WS2 IF nanoparticles with sizes below 100 nm were readily produced. However, the initially formed WS2 IF nanoparticles were poorly crystallised with numerous defects and disconnections, which is consistent with the results of other researchers. In this project, an additional annealing process was introduced to eliminate these defects and disconnections. After this process, well-crystallised WS2 IF nanoparticles were formed, which should exhibit improved mechanical properties and stability. In addition to the WS2 IF nanoparticles, ZrS2 was also prepared using the same route from the reaction of ZrCl4 with S. Unlike the WS2, the generated ZrS2 was in the form of nanoflakes with sizes below 30 nm. Consequently, these nanoflakes exhibited a strong quantum confinement effect and good photocatalytic performance for the decomposition of 4-NP. Based on the investigation of the WO3 sulphidation mechanism, novel W@WS2 and WS2@WS2 nanorattles were designed and first synthesised using a simple gas-solid reaction. The as-synthesised nanorattles were composed of tiny, moveable W/WS2 cores and continuous WS2 shells with much larger sizes. By simply tailoring the processing parameters, several types of nanostructures, including WS2 nanoflakes, IF nanoparticles and nanorattles (with desirable core size and shell thickness) were selectively prepared. Moreover, it was observed for the first time that the as-prepared nanorattles exhibited excellent catalytic activities, which were close to or even better than their much more expensive Au- and Pt-based counterparts.

Pure submicron-sized zirconium diboride (ZrB2) powder was synthesised via a molten salt mediated reduction route using ZrO2, Na2B4O7, and Mg powders as the starting raw materials and MgCl2 as the reaction medium. By using appropriately excessive amounts of Mg and Na2B4O7 to compensate for their evaporation losses, ZrO2 can be completely converted into ZrB2 after 3 h of firing at 1200 °C. This synthesis temperature is 100-500 °C lower than that of other conventional synthesis techniques. In addition, the formation of undesirable Mg3B2O6 can be effectively suppressed. To a large extent, the prepared ZrB2 particles preserved the shapes and sizes of the original ZrO2 particles, indicating a template growth mechanism for their formation in which ZrO2 functions as the reaction template. Using this developed synthesis method, submicron-sized and nanosized zirconium carbide (ZrC) powders were synthesised in the reaction system of ZrO2-Mg-carbon black using NaCl-KCl as the reaction medium. The synthesis temperatures were 950 and 850 °C for the former and the latter powder size, respectively, which are much lower temperatures than those used in most of the reported methods. Compared with the submicron-sized ZrO2 powders, the finer ZrO2 particles considerably enhanced the reaction rate and thus the completion of the reaction at a lower temperature. The resulting ZrC particles exhibited two different morphologies: one retained the shapes and sizes of the original ZrO2, and the other retained those of the starting carbon black, suggesting that both ZrO2 and carbon black had acted as reaction templates. In addition, the 2D-nanostructure of a non-layered structure material, titanium carbide (TiC), was fabricated. The novel TiC nanosheets (TNS) and TiC-coated graphite nanosheets (TCNS) were produced at 950 °C for 8 h and 900 °C for 5 h, respectively, in KCl molten salt using graphite nanosheets (GNS) as both a carbon source and reaction templates. The produced TNS and TCNS retained the shapes, sizes and thickness of the original GNS to a high degree, indicating that the GNS had acted as the reaction template. For TCNS, a lower molar ratio of Ti/C required a lower synthesis temperature and/or a shorter holding time. This effective processing technique was also employed to produce TiC foams at 1050 °C for 4 h using carbon foam as the reaction template. This synthesis temperature is significantly lower than that (>1450 °C) used in most of the other techniques. The resultant pores were clear of any undesired phases such as impurities and/or membranes, and the cell-networks were free of surface cracks and holes. The cell-networks, pore sizes, and cell sizes of the synthesised foams were well defined by those of the original carbon foam, suggesting a template growth mechanism of the formation of the TiC foam.

Carbon nanotubes (CNTs) have been the subject of intensive research for nearly two decades, and this is due to their exceptional lightness, large aspect ratio, extraordinary mechanical, electrical, thermal properties and additional multi-functional characteristics. Ceramics have high stiffness and good thermal stability with a relatively low density, and they are an important constituent in the fabrication of advanced composites where high thermal and chemical stability are important. However, brittleness has limited their application in many structural applications. The combination of ceramic (alumina in particular) and CNTs, endeavouring to develop functional composites, offers a very attractive system for research and development. The fabrication of such alumina-CNT composites at bulk scale is therefore highly desirable for industrial applications. However, the synthesis of such composites possesses many technical challenges which need to be addressed. Poor synergy between the matrix and CNTs, potential damage to CNTs, obtaining a uniform and agglomeration-free distribution of CNTs within the matrix, and high cost of CNTs and processes involved in their composite fabrication have proved to be the significant challenges. In this thesis, the focuses are laid on addressing these issues and on the fabrication of specially engineered composites for particular applications such as filter and composites with improved mechanical properties. In this regard, it has been tried to directly fabricate CNTs in different ceramic matrices based on the application requirements. After that, the critical issues and challenges in the fabrication of these functional materials have been clearly investigated and by introducing novel methods and approaches, it has been tried to solve these problems. Also, a new polymer-ceramic-CNT composite has been fabricated by using two different thermoset (epoxy resin) and thermoplastic (polyamide 12) matrices. In this regard, good interfacial bonding between the composite elements along with good wettability of ceramic and CNTs with polymer had to be addressed as critical issues and challenges in the fabrication process. If the adherence at the interface is not strong enough, the material will tear and fail easier. In contrary, a tailored functionalization of CNTs can lead to an improved wettability and as the results, strong interfacial adhesion and bonding between the composite elements. These dominating factors will improve the degree of filling which results in existence of fewer voids inside the composite. These voids will act later as stress points and reduce the composite strength. At the end, the mechanical properties of the fabricated samples have been assessed. The CNT filters have been tested in the removal of bioorganic (yeast cells) and inorganic (heavy metal ions) contaminants from water, and of particulates from air, and they all showed very promising results. More than 99.6% of the air particles (size ranges from 0.3 to 10 µm) were filtered using 300 mm long CNT filter. A complete removal of heavy metal ions from water was reported particularly for single ion. 98% of the yeast cells were filtered. Different factors involved in the filtration efficiency such as ceramic pore size, length of filters, CNT loading and injection rates have also been discussed. Furthermore, the mechanical properties (compression test, hardness and impact test) of the composite materials (including ceramic-CNT, epoxy resin-ceramic-CNT and polyamide-ceramic-CNT composites) have been assessed. During impact test, the epoxy resin-ceramic-CNT composite absorbed 117.2% and 32.7% more energy compared to the pure epoxy resin and epoxy resin-ceramic composite, respectively. The epoxy resin-ceramic-CNT composite sustained 40% more elastic deformation before breakage compared to the epoxy resin-ceramic composite as a result of the CNT reinforcement. The addition of CNTs to the polyamide12-ceramic composite increased its yield stress by 41%. All of these results represent a big leap towards practical applications for the composite reported in the thesis, which may open up new opportunities for CNT engineering at industrial scales, due to the easy fabrication methods introduced and the promising performance they have exhibited.