Direct sunlight-active Na-doped ZnO photocatalyst for the mineralization of organic pollutants at different pH mediums

•Na-doped ZnO (Na-ZnO) nanosheet was prepared and used as a photocatalyst for methylene blue dye photocatalytic degradation.•Density functional theory (DFT) calculations used for proving the electronic and crystal structures of Na-ZnO.•Na-ZnO has high photocatalytic activity and stability at differe...

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Bibliographic Details
Published in:Journal of the Taiwan Institute of Chemical Engineers 2020-10, Vol.115, p.187-197
Main Authors: Elsayed, Mohamed Hammad, Elmorsi, Taha M., Abuelela, Ahmed M., Hassan, Ahmed E., Alhakemy, Ahmed Zaki, Bakr, Mostafa F., Chou, Ho-Hsiu
Format: Article
Language:English
Subjects:
DFT calculations
Direct sunlight
Na-doped ZnO
Photocatalytic degradation
Precipitation method
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Summary:•Na-doped ZnO (Na-ZnO) nanosheet was prepared and used as a photocatalyst for methylene blue dye photocatalytic degradation.•Density functional theory (DFT) calculations used for proving the electronic and crystal structures of Na-ZnO.•Na-ZnO has high photocatalytic activity and stability at different pH's.•Under direct sunlight, Na-ZnO decolorized more than 99.5% and mineralized 98.3% of MB.•Na-ZnO have high photostability reach to 7 recycle with the same efficiency. This work reports the preparation of Na-doped ZnO (Na-ZnO) as a promising photocatalyst under sunlight through a very simple precipitation method. The crystal and electronic structures of the prepared Na-ZnO were characterized by experimental techniques and Density Functional Theory (DFT) calculations. Where the DFT calculations revealed that the effect of Na-doping on the ZnO electronic structure is consistent with the experimental observations and the bandgap value found to be decreasing. Under direct sunlight, the as-prepared Na-ZnO decolorized more than 99.5% of the methylene blue dye (MB) after 1.5 h and led to mineralization of 98.3% of it after 3 h. While pure ZnO decolorized only 35% of MB dye at the same conditions. The prepared Na-ZnO has a promising photocatalytic activity at different pH's and high photostability reaching to 7 recycle with the same efficiency. Finally, the primary active species produced during the photocatalytic reaction were determined and the photocatalytic mechanism was elucidated.
ISSN:1876-1070
1876-1089
DOI:10.1016/j.jtice.2020.10.018