PhD student: Yixuan (Jenifer) Wang, Supervisors: Wei Gao & Filicia Wicaksana
Electrospun Silicon Oxycarbide (SiOC) Fibre Mats and Its Composites
Abstract: This work presents the preparation of ultrafine SiOC fibre mats through the electrospinning/sol-gel method, where specific concern has been laid on the elimination of the spinning-aid, compositional control, porosity control, and surface functionalization of the fibre mats. The influence of preparation parameters on the morphology and composition of resulted SiOC fibre mats and its composites have been thoroughly studied, and their performance in energy and environmental-based applications have been investigated.
Through the concentration and configuration design of the precursor sols, ultrafine SiOC fibre mats ( = ~256.7 nm) were prepared via a spinning-aid-free electrospinning/sol-gel process; Modification of the precursor system through polymer blending and post-treatment resulted in SiOC fibres with flexible composition (at.%C: 22.3 – 49.5) and varied porosities (hollow and surface porous), such SiOC fibre mats demonstrated a specific capacitance of 11.8 F/g when used as supercapacitor electrodes. It also has excellent dye adsorption capacities (15.85 mg(MB)/g(SiOC)). Further functionalisation of the SiOC fibre mats through the hydrothermal method generated hierarchically structured SiOC/TiO2 composites fibre mats, showed favourable water-remediation capabilities of photocatalytic pollutant removal and oil-water-separation.
PhD student: Xiaoyu Yue, Supervisors: Wei Gao and Filicia Wicaksana
Titanium Dioxide-Based Nanocomposites as Highly Efficient Electrocatalysts for Methanol Oxidation Reaction
With the fast-increasing energy demands and rapid depletion of fossil fuel resources, direct methanol fuel cells (DMFCs), as an alternate clean energy source, are becoming one of the most promising replacements for fossil fuels. DMFCs have several advantages including high specific energy, high energy conversion efficiency, easy to operate, easy to transport, and clean for portable applications. Platinum-based catalysts are the most widely preferred anode catalysts for methanol oxidation reaction in DMFCs. However, the sluggish anodic kinetics, high cost of noble metals and unstable carbon supporting materials have hindered their wide applications. Therefore, exploring and developing low-cost, high-performance, and durable anode catalysts have been the major challenge for the application of DFMCs. The combination of metal particles, carbon materials, and TiO2 has been considered as the promising pattern to improve its conductivity.
We designed and prepared novel non-precious metal Ni/TiO2-C catalysts for methanol oxidation reaction. With improved surface area and enhanced conductivity, this catalyst displayed superior catalytic performance and stability. As a non-precious metal catalyst, this new-style catalysts significantly reduced the cost of Pt containing catalysts and open a new path for the development of a large scale methanol oxidation catalysts.
PhD student: Sinemobong Essien, Supervisors: A/P Saeid Baroutian and Professor Brent Young
Recovery of Bioactive Compounds from Kanuka Leaves using Subcritical Water Extraction
Sinemobong completed her PhD research on the recovery of bioactive compounds from Kānuka, a Māori indigenous plant, using a novel extraction technology. Kānuka is an especially extensive resource of underutilised Māori land and the goal of Sinemobong’s research was to develop a new technology to extract maximum value from this Māori indigenous plant. She used a novel extraction technology, subcritical water extraction, to obtain bioactive extracts from Kānuka leaves. Since this is the first report on this topic, phytochemical analyses and biological screenings were conducted to quantify and qualify the isolated bioactive components in the extract. These analyses were achieved via a variety of established spectroscopic and chromatographic techniques. Following this, a techno-economic and environmental impact assessment under those optimised conditions were conducted to check the economic feasibility of upscaling the process from lab-scale to industrial level. Another novelty in the research was the evaluation of the technology readiness level for subcritical water extraction. This aspect of the research has not yet been recorded in the literature, even with the growing awareness in this technology.
Sinemobong worked closely with Māori communities of East Cape and Ngāti Porou to combine Mātauranga Māori concerning the alimental benefits within Kānuka with the technologies in chemical and food process engineering. This is Vision Mātauranga in authentic action as she applied the results of her research to the benefit of the community.
PhD student: Tech Nam Ang, Supervisors: A/P Saeid Baroutian and Professor Brent Young
Adsorptive Removal of Volatile Anaesthetics from Waste Medical Gas
The application of inhalation anaesthetics may constitute up to 63% of the carbon footprint from operating theatres. Volatile anaesthetics have high global warming potential. They are metabolised only minutely by patients with the rest released inevitably to the atmosphere causing global warming, and in some cases, ozone depletion.
Teck Nam developed a new adsorbent system for the complete removal of anaesthetic gases. He adsorbent was developed by surface modification of activated carbon using various approaches, such as (a) aqueous oxidation using nitric acid, ammonium persulfate and hydrogen peroxide; (b) oxidative hydrothermal surface modification; and (c) nitrogenation using ammonia solution. The surface physical and chemical properties of the oxidised samples were characterised and associated with adsorption of sevoflurane measured at fixed conditions. The adsorption conditions were determined from breakthrough analyses of continuous fixed-bed adsorption of sevoflurane using selected commercial activated carbons, including E-GAC. The Conductor-like Screening Model for Real Solvents (COSMO-RS) model was applied to predict the interaction between sevoflurane molecule and surface functionality.