Bringing Transition Metal Dichalcogenides to the Forefront: Advancements in Gas Sensing Beyond Metal Oxides

Identifier:  TDX:4395

Handle: https://hdl.handle.net/20.500.11797/TDX4395

Authors:  Malik, Shuja Bashir

Abstract:
This thesis demonstrates the transition of gas sensing materials from high-power-consuming semiconductor metal oxides to edge-enriched transition metal dichalcogenides. The thesis was planned to first understand the gas sensing behavior of metal oxides, especially WO3, and subsequently progress towards transition metal dichalcogenides. In this thesis, we not only successfully transitioned from metal oxides but also utilized transition metal dichalcogenides in selectively detecting various toxic gases like NO2 and NH3. Moreover, we accomplished the use of hybrids of metal oxides and transition metal dichalcogenides to lower the operating temperatures of the metal oxides from 300°C to 150°C. WO3 nanowires with controlled morphology were synthesized using AACVD and decorated with CeO2 nanoparticles for gas sensing, showing enhanced and selective responses to ethanol. Additionally, a novel APCVD technique was developed to synthesize large-scale WS2 sheets in powder form, demonstrating exceptional NH3 sensing properties. Furthermore, WS2-graphene hybrid thin films for ultra-low NO2 detection, with an experimental limit of detection (LoD) of 10 ppb, were achieved. Integrating heterojunctions of TMDs and metal oxides were demonstrated to enhance sensitivity and reduce operating temperatures for NO2 sensing. Moreover, MoS2 sheets were decorated with Pd nanoparticles using AACVD for highly sensitive and selective hydrogen detection. Finally, in pursuit of self-powering devices, ZnO-piezoelectric polymer composites were fabricated for flexible piezoelectric nanogenerators, aiming to advance energy harvesting technologies for wearable electronics.