Synthesis and application of cu-doped zinc oxide Zn1-xCuxO (x = 0.01, 0.02, 0.03, 0.04, 0.05) based microstructures for the elimination of methylene blue dye pollutant under sunlight
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Date
2021
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UMT, Lahore
Abstract
Herein, copper (Cu) doped zinc oxide (ZnO) namely Zn1-xCuxO (x = 0.01, 0.02, 0.03, 0.04, 0.05) microstructures are synthesized by hydrothermal method for photocatalytic activity. The grown samples were characterized with XRD, FTIR, SEM and UV-vis. The XRD results confirmed the successful doping of Cu ions without altering the basic hexagonal structure of ZnO. FTIR results also confirm the presence of metal-oxygen bond vibration related to Zn-O bonds. UV-vis results showed that the energy bandgap decreased with the increase in the doping concentration of Cu in the ZnO host. Photocatalytic activities of all synthesized samples were tested against methylene blue (MB) dye under sunlight irradiation. The Zn0.95Cu0.05O photocatalyst has shown the best photocatalytic activity with 99.9% elimination of MB dye within 60 min, as compared to the pure ZnO and 1%, 2%, 3%, and 4% Cu doped ZnO. In comparison to the other catalyst, the value of the rate constant for Zn0.95Cu0.05O has been observed to be greater. The excellent photocatalytic activity of Zn0.95Cu0.05O is accredited to, 1) the presence of Cu ions that successfully suppress high recombination of electron-hole pair which, in turn, find enough time to produce extra reactive species for degradation MB dye and 2) Lower energy bandgap of ZnO by 5% Cu doping in visible region which leads to a higher number of electrons excitation from valence band to conduction band. Hence, the present finding introduces a strategy to reduce the energy bandgap of ZnO from UV to the visible region to make it efficient for practical photocatalytic applications under sunlight.