MXene based materials for energy storage and separation

MXenes, a fresh family of 2D carbides and nitrides of transition metals, have garnered tremendous research interest over the past decade owing its unique combination of massive metallic conductivity and hydrophilicity. This graphene-like 2D material with its flexibility to morph into the form of membranes and thin films makes them suitable for a number of applications including supercapacitors, batteries, water purification and gas separation. Nevertheless, the high oxidation potential and a complex etching process limits the commercialization of MXenes. This thesis seeks to explore the performance of Ti3C2Tx MXenes for two important but diverse applications of energy storage and water purification. Firstly, thin film MXene electrodes were prepared and tested for their electrochemical performance in a three-electrode cell. Several characterization techniques were performed to analyse the chemical composition, structure, morphology and surface area of the MXene samples. Some key findings include the oxidation of delaminated Ti3C2 MXene into anatase when stored at normal room temperature conditions and high equivalent resistivity of the MXene electrode as a result of oxygenated functional groups. A high specific capacitance of ~127 F/g was obtained via cyclic voltammetry at a scan rate of 0.5 mV/s indicating its use as electrodes in supercapacitors. Secondly, MXene membranes were synthesized using the vacuum filtration method and tested for water flux and salt rejection. The membrane exhibited a hydrophilic character with a contact angle of 60˚ and its interlayer spacing was found to approximately increase from 9 Å to 13.5 Å due to the hydration effect. The pressure-driven filtration test indicated a high water flux of 307 LMH at 80 kPa and the membrane was able to permeate more than 90% ions as a result of size exclusion effect of the ion size and the interlayer spacing