FUNCTIONAL GRAPHENE-BASED MATERIALS AND THEIR APPLICATIONS IN ENVIRONMENTAL REMEDIATION AND WEARABLE ELECTRONICS

Abstract

The rapid expansion of fast fashion industry brings out environmental concerns such as dyestuffs-related water pollutions and waste textiles. Conventional wastewater-disposal strategies emphasize the optimisation of photocatalytic activity to improve pollutant degradation efficiency, while the adsorptivity, recyclability and sustainability of photocatalysts are largely ignored. The overproduced textiles are still in urgent of being recycled and reutilised in eco-friendly approaches. In this thesis, a scalable dyeing technology is employed to achieve green and sustainable reutilisation of waste textiles. The functionalised TiO2/reduced graphene oxide wool fabrics show excellent sustainability, remarkable adsorbing capacity and enhanced photocatalytic performance. By taking advantages of these properties, we develop an integrated strategy of night-time adsorption and day-time photodegradation which could significantly optimize the dyestuffs degradation efficiency. The concept of waste textiles reutilisation and wastewater treatment in this work provides practical potentials in the efficient and sustainable environmental remediation. On the other hand, graphene-based materials have been widely used in wearable electronics for their superior properties in electron and heat transport. However, recent wearable devices are mostly assembled by coating graphene into flexible substrates and stretchable encapsulations. Such fabrication technologies sacrifice the physical comfort, wettability and washability which are the essential elements to wearables. In this thesis, we report a continuous twisted graphene fibre with high tensile strength (369 MPa) and outstanding breaking strain (48.5%) by wet-fusing assembling method, which could be directly woven into fabric-based breathable, wettable and washable strain sensors with anti-jamming properties to bend, pressure, temperature and humidity. The strain sensor displays undifferentiated performance of sensitivity, stability and durability both in air and underwater. We also optimize the mechanical properties of twisted graphene fibre by integrating TiO2 nanoparticles into the fibre. The as-prepared twisted graphene/TiO2 fibre has improved tensile strength (515 MPa) and novel photocatalytic performance, which can be assembled into highly sensitive (gauge factor of 350) and self-cleaning stain sensor with extra reliable sensing properties in harsh environment. Moreover, we discover a graphene oxide functionalised Coolmax humidity sensor with ultrafast response/recovery time (0.6 s) after studying textile-based humidity sensors constructed from various natural and synthetic fibres (i.e., cotton, wool and Coolmax). The humidity sensor exhibits wide applications in respiration sensing, diaper wetness alert and woven fabric touchpad.

Date of Award	31 Dec 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Xuqing Liu (Supervisor) & Yi Li (Supervisor)