AbstractsEngineering

Vanadium dioxide has shown great potential for many applications such as smart window coatings, switches and sensors because of their unique thermochromic properties. Many methods have been developed to prepare VO2 thin films / nanoparticles to understand the phase transition mechanisms, however, there are still some limitations in the synthesis of particles and films, due to difficulties in synthesizing crystalline VO2 (M/R) nanoparticles, high cost for film fabrication, complicated preparation procedures and toxic precursors, and this has impeded the progress in commercialization. This thesis aims to study the preparation of vanadium dioxide nanoparticles and thin films and their functional properties, using a combinatorial approach involving experimental and computational aspects. A simple but efficient hydrothermal method has been developed and used to synthesize vanadium oxide and sodium vanadium oxide nanoparticles with promising potential in gas sensing. The thermochromic properties of single VO2 nanoparticle have been measured using Ti / Au electrodes under a scanning electron microscope assisted system. The electrodeposition and spin-coating methods have been utilized to deposit VO2 thin films, and the thermochromic properties have been measured under different conditions. In order to fundamentally understand the metal-doped VO2 nanocompounds and the mechanisms governing the temperature-related phase change, the computational simulation method ̶ density functional theory (DFT) was employed to quantify the relationship between crystallographic and electronic structure and functions. The findings in this thesis can be used to design and construct unique nanostructures with unique properties promising for applicability as smart window coatings and gas sensors.