Development of Nanostructured Metal Oxides for Their Applications in the Environmen
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2026
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Abstract
This thesis focuses on the development and optimization of nanostructured metal oxide thin films for
multifunctional environmental applications. ZnO- and CuO-based thin films were synthesized using
controlled deposition techniques, combined with dopant engineering and multilayer heterostructure
design in order to tailor their structural, optical, and surface properties.
In the first stage, pure and doped ZnO thin films were systematically investigated by varying
precursor concentration, deposition parameters, and annealing conditions. The photocatalytic activity
of the optimized films was evaluated through the degradation of organic pollutants under UV
irradiation. Experiments showed that pure ZnO has a limited capacity to degrade methylene blue.
Performance was enhanced using non-metallic dopants such as urea, which outperformed thiourea,
and metallic dopants like silver. The optimal silver concentration was 5%, and the addition of 20%
urea to this compound achieved nearly complete dye degradation within 90 minutes.
Subsequently, Ag-doped ZnO thin films were deposited on silicon substrates for ultraviolet
photodetector applications. Structural analyses confirmed the preservation of the wurtzite phase with
progressive lattice modification induced by silver incorporation. Electrical measurements, including
current-voltage (I–V) characteristics and time-dependent photoresponse, demonstrated that a 1%
silver doping level yielded instead provided the highest electrical response under UV illumination.
Finally, Mg-doped ZnO thin films and ZnO/CuO multilayer heterostructures were investigated for
CO₂ gas sensing applications. For CO₂ gas sensing, the study was divided into two parts: In the first
part, 7% Mg-doped ZnO demonstrated exceptionally high sensitivity, reaching 461.76%. In the
second part, multilayer ZnO/CuO structures were investigated, showing that pure ZnO delivered
superior sensing performance compared to multilayer configurations.
Overall, these findings highlight that controlling the type and concentration of dopants in ZnO can
significantly enhance its performance in photocatalytic and gas sensing applications, paving the way
for the development of more efficient and reliable devices.