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This thesis developed an environmentally friendly plasma process to generate advanced separation membrane materials. The membranes of tunable properties exhibited high flux and found applications in solvent separation exhibiting promising performance for cost-effective dewatering of alcohol solutions.

This thesis investigated nitrate and hydrogen peroxide generation in contact with water and studied this plasma-treated water for plant growth. The plasma-treated water significantly stimulated wheat seedling growth, as nitrate serves as a N fertilizer and hydrogen peroxide acts as a signalling molecule for plants. This thesis suggests plasma-treated water has potential for wider applications in agriculture.

Plasma technology is an environmentally friendly non-thermal approach to effectively decontaminate cow milk with extended shelf life whilst maintaining nutrition compared to pasteurization. The results demonstrated that plasma treatment is an alternative to pasteurization and may also be used to treat other milk types, such as human, goat, buffalo etc.

This work demonstrates that diamond-like nano-carbons can be rapidly grown at atmospheric pressure and near ambient temperature in Ar gas bubble discharge in liquid ethanol. The method uses a discharge between point-to-plate electrodes immersed in ethanol, with plasma being generated inside Ar gas bubbles introduced through the needle electrode. The ethanol was dissociated at the liquid/gas interface into reactive species such as C2 and CH, which are the primary species responsible for diamond formation. A mixture of lonsdaleite nano-diamonds, amorphous carbon nano-spheres, and a graphitic carbon network, was formed. The rapid bubble movement distributes the reaction products almost immediately into the liquid phase, ensuring that nucleation of new material continues throughout the process. This simple, inexpensive and fast process avoids the elevated temperatures and extreme pressures of current methods.

The potential of combining cold plasma and thermal treatment for the nanofabrication of advances semiconductors was investigated.

This study explored plasma techniques to improve the efficiency of dye sensitised solar cells and perovskite solar cells. It was found that plasma functionalization of TiO2 improved dye absorption, thereby improving efficiency. Controllable nitrogen doping of TiO2 was achieved by a unique system that combines plasma with heat treatment. The doping reduced the band-gap of TiO2. A crystalline TiO2 thin film on plastic substrates was successfully achieved by a low temperature plasma method, which could potentially allow such soft and flexible substrates to be used for solar cells.

Improvement of the binding of polypyrrole with PVDF (polyvinylidene fluoride) thin film using low pressure plasma was studied. The effects of various plasma gases i.e., Ar, O2 and Ar + O2 gases on surface roughness, surface chemistry and hydrophilicity were noted. The topographical change of the PVDF film was observed by means of scanning electron microscopy and chemical changes by X-ray photoelectron spectroscopy, with adhesion of polypyrrole (PPy) by abrasion tests and sheet resistance measurements. Results showed that the increase in roughness and surface functionalization by oxygen functional groups contributed to improved adhesion and Ar + O2 plasma gave better adhesion.

Tariq worked in the area of electronic textiles. He coated polyester fabric and PVDF films with polypyrrole. Plasma treatment was used to improve binding of coatings over the surface. He investigated in detail, the factors responsible for adhesion improvement using XPS, AFM, SEM, contact angle, abrasion tests and conductivity measurements. Different plasma gases, plasma power and plasma modes were investigated to get optimum bonding data. His investigations pointed towards improved surface oxygen functionalization and suitable surface morphology for improved bonding.

A novel recyclable and flexible membrane was prepared for the removal of oil spills and organic dye pollutants, by functionalizing polyester textiles with reduced graphene oxide@ZnO nanocomposites using a layer-by-layer technique. The membrane showed efficient water/oil separation, and the amount of oil adsorbed by the membrane could be up to 23 times its own weight. The adsorption capacity was largely retained during many adsorption recycling cycles. The membrane also displayed highly efficient removal of a dye pollutant from water under simulated sunlight. The membrane maintained a near-original removal efficiency after five cycles of dye removal. This new type of membrane may find practical applications in the large-scale separation of organic pollutants from water, particularly in the field of oil spills clean-up and dye removal from industrial effluent.

During his PhD studies, Zhiqiang published 5 journal paper and 7 conference paper and also participated in the development of the first Plasma Research Laboratory at Institute of Frontier Materials.

Pronounced and stable pseudocapacitance has been found in flowerlike FeTiO3 nanostructures that were synthesized from ball-milled ilmenite (natural mineral) under mild hydrothermal conditions. Each nanoflower is composed of many thin petals with a thickness of 5-20 nm and a width of 100-200 nm. The formation of these flowerlike nanostructures is attributed to a dissolution-precipitation mechanism involving an intermediate sodium-containing phase. Electrochemical properties of the obtained FeTiO3 nanostructures are evaluated in aqueous electrolytes. The capacitance of 122 ± 14.5 F/g is measured in 1 M KOH aqueous electrolyte at the current rate of 500 mA/g, and 50 ± 6 F/g is retained at 5 A/g. The material has good long-term cycling stability. According to our data, FeTiO3 nanostructures show functionality as an electrode material for supercapacitors.

In this paper, 3-D finite element modeling and simulations are carried out to investigate the bending deformation of a single-walled carbon nanotube cantilever biosensor due to mass attached, and addition of a nano-scale particles to the beam tip resulting from the bioparticle detection. In addition, an algorithm for an electrostaticmechanical coupled system is developed. The computed results are in excellent agreement with the well known electrostatic equations that govern the deformation.