Publication: Development of ZnO nanorods on supporting substrates for photocatalyst applications
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Date
2024-02
Authors
Siti Nor Qurratu Aini binti Abd Aziz
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Abstract
Zinc Oxide (ZnO) nanorods based photocatalyst suffers from performance deterioration over time due to loss of ZnO nanorods in the particle form. In addition, a low cost and rapid synthesis technique is needed for mass production of ZnO nanorods particularly on supporting substrate. In this work, ZnO nanorods (particle and nanorods immobilisation on substrate) were successfully synthesized by solution precipitation technique and direct heating (DH), respectively. The results were confirmed by X-ray Diffraction Spectroscopy (XRD) and X-ray Photoelectron Spectroscopy (XPS) analysis. The small IUV/IVis ratio in Room Temperature Photoluminescence (RTPL) analyses indicate that the ZnO contained crystal defects such as oxygen interstitial, zinc vacancy or oxygen vacancy. The ZnO nanorods demonstrated photodegradation of RhB dye under exposure of UV irradiation, and selectively removal on Cu2+ ions and Ag+ ions. The photodegradation of Rhodamine-B (RhB) dye complied to 1st order kinetic reaction. The scavenger study indicated that OH● free radicals and O2●- free radicals were the dominant species that actively involved in the photodegradation of RhB dye. The ZnO particles demonstrated the highest photodegradation efficiency (PE%) (72%), but deteriorated in the cyclic test. ZnO nanorods immobilised on PET fibre demonstrated decrease in PE% was attributed to reduction of surface area as the ZnO nanorods were stacked on each other. The PE% of ZnO nanorods grown on kanthal wires/meshes were the lowest. This was because of smaller catalyst loading was used in the photocatalytic test. In term of its reusability, ZnO nanorods grown on kanthal wires/meshes were the best. The selection of
polymeric flexible substrate or rigid substrate depends on the usage point in the wastewater treatment. Lastly, DH technique is successfully developed to synthesise ZnO nanorods in short duration (15 min), consuming low electrical power (≤0.060 kWh). It is a potential synthesis technique that can be upscale for larger substrate size and mass production of ZnO nanorods for the fabrication of wastewater treatment module.