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Electrochemical supercapacitors (ES), or ultracapacitors, store energy using either reversible adsorption of electrolyte ions (electrochemical double layer capacitors) or fast surface redox reactions on its electrodes (pseuodocapacitors). Currently, they are used together with batteries or fuel cells when high-power delivery or uptake is required. They have exceptional features such as high power density, high cycle efficiency, fast charging-discharging rate, long lifecycle, and safe operation. Therefore, they have attracted tremendous interest as next generation energy conversion and storage systems, ranging from portable wearable electronics to hybrid electric vehicles. However, low energy density is the main drawback to use ES as a stand-alone energy storage system. Thus, their performance should be improved to fulfil the requirements of ever-growing energy demands of progressing global economy and industry. In addition, most of the ES electrodes are fabricated from powders which makes them unsuitable for their potential use as wearable lightweight flexible devices in the future. Considering the requirements of future industrial applications of ES, this thesis focuses on synthesizing high performance, flexible, mechanically stable, lightweight, eco-friendly, and low cost ES electrodes using green, scalable, and inexpensive fabrication methods. To develop highly efficient electrode materials suitable for practical applications in a flexible design, novel synthesis procedures were explored to incorporate pseudocapacitive materials (metal oxides and electrically conductive polymers) into three-dimensional and flexible conductive carbon materials to obtain multicomponent hybrid materials. Therefore, hybrid materials reported in this thesis are binder-/conductive agent-free and also have enhanced three-dimensional nanostructures which promote energy storage. Simplicity of the fabrication methods also enable large scale and economical production of flexible and mechanically stable materials which can be directly used as ES electrodes. First, electrode materials with a unique nanostructure was developed for supercapacitor applications based on carbon fibre fabric (CFF) / MnO2 hybrid materials, in which MnO2 was uniformly coated on the surface of CFF. A green hydrothermal method was used to functionalize CFF with coral-like MnO2 nanostructures to improve the electrochemical performance of the hybrid composites. The morphological, structural, and crystalline properties of composites were analysed by using various techniques to confirm the deposition of coral-like MnO2 on CFF. The electrochemical performance was examined in a three-electrode system and cyclic voltammetry results reveal the superior specific capacitance of 467 F g-1 at a scan rate of 5 mV s-1. The cycling performance test revealed that the capacitance retention was 99.7% and the coulombic efficiency remained as high as 99.3% after 5000 cycles, demonstrating an outstanding electrochemical stability of the coral-like MnO2/CFF composite electrode. Second, synthesis method used in the first study was optimised to obtain three novel nanostructured MnO2 layers on flexible CFF substrates. It was observed that different morphologies of MnO2 could be grown on carbon fibres by adjusting the concentration of precursor solution. The morphological, structural, and crystalline properties of the composites were analysed by using various techniques to confirm that MnO2 nanostructures were successfully anchored on CFF. The electrochemical performances of the nanostructured MnO2/CFF composites were examined in two-electrode symmetric cell configuration in 1 M Na2SO4 electrolyte. Among three different morphologies, nanoplate type MnO2/CFF electrode had the best electrochemical performance (528 F g-1 at 0.5 A g-1 current density). In addition, binder and conductive agent free, flexible MnO2/CFF composite electrode had excellent cycling stability and coulombic efficiency. Finally, activated CFF (ACFF) / reduced graphene oxide (RGO)/polyaniline (PANI) composite flexible electrodes were prepared by in-situ polymerization method. Polymerization of aniline was optimized by adjusting aniline concentration to obtain PANI nanowire arrays on the three-dimensional flexible carbon based substrate. Electrochemical performance of ACFF/RGO/PANI composite was compared with ACFF and ACFF/RGO electrodes in two-electrode symmetrical cell configuration in 1 M H2SO4 electrolyte. The results indicated that ACFF/RGO/PANI exhibited outstanding area normalized capacitance due to synergistic effect between ACFF, RGO, and PANI. The facile synthesis method of the composite electrode using textile based substrate enables the possibility for fabrication of high-performance flexible energy storage devices.

A novel method for the production of singlet oxygen from H2O2 was developed. A combination of iodoarene (ArI), methyltrioxorhenium (MTO), and H2O2 in the presence of pyridine as the co-catalyst efficiently produced singlet molecular oxygen (O-1(2)) under biphasic conditions. The existence of O-1(2) was demonstrated by trapping experiments with aromatic dienes, 1,3-cyclodienes, and alkenes. The mechanism of O-1(2) production from the iodoarene/MTO/35 % H2O2 system and the reaction scope was also discussed.

A series of (1S,1'S)-4,4'-biquinazoline-based primary amines were prepared from natural amino acids via a six-step reaction sequence of protection and condensation followed by key synthetic steps including chlorination, nickel(0)-mediated homocoupling, and deprotection. These novel amines were screened for the asymmetric ethylation of aryl aldehydes to yield alcohols with an (S)-configuration with enantiomeric excesses (ee) varying from 2% to 95%. (C) 2011 Elsevier Ltd. All rights reserved.