Speaker
Description
Effective air quality monitoring in mining environments remains challenging due to limited access to reliable, accurate, and fast gas-sensing technologies. Semiconductor metal oxide gas sensors represent a promising alternative owing to their simple design, robustness, and high sensitivity. This study investigates the synthesis, structural, and morphological characterization, and gas sensing performance of nanostructured tellurium dioxide (TeO2). TeO2 nanostructures were prepared from Tellurium (Te) powder oxidized with nitric acid (HNO3) and/or hydrogen peroxide (H2O2), followed by hydrothermal treatment to tailor morphology and surface properties, which are critical for gas-solid interactions. The X-ray powder diffraction analysis revealed that HNO3-oxidized TeO2 crystallized in the α-TeO2 phase, with a tetragonal structure and space group P41212, in good agreement with the crystallographic information file (COD-1537586). In contrast, the H2O2-oxidized TeO2 exhibited a mixed phase composition, indicating incomplete phase transformation from Te(powder) to TeO2. Scanning electron microscopy images showed that H2O2-oxidized TeO2 consisted of agglomerated nanoparticles, whereas the HNO3-oxidized TeO2 formed well-defined hollow octahedral structures. This morphology provides an increased surface‑to‑volume ratio and accessible diffusion pathways, which are advantageous for enhanced gas adsorption and charge transfer. Diffuse reflectance spectroscopy indicated a higher reflectance (~80%) across the visible region for HNO3-oxidized TeO2 compared to H2O2-oxidized TeO2 (~70%). The optical band gap energy extracted using the Kubelka-Munk function was 3.8 eV for HNO3-oxidized TeO2 and 3.93 eV for the H2O2-oxidized TeO2 sample, suggesting subtle variations in electronic structure related to synthesis conditions. Furthermore, to study the sensitivity and selectivity of the materials, the HNO3-oxidized TeO2 was tested for NO2, CH4, SO2, NH3, and H2S at various operating temperatures.
| Apply for student award at which level: | MSc |
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| Consent on use of personal information: Abstract Submission | Yes, I ACCEPT |