Enhanced photocatalytic activity of Cu and Ni-doped ZnO nanostructures: A comparative study of methyl orange dye degradation in aqueous solution

Md Rashid Al-Mamun; Md Zaveed Iqbal Rokon; Md Abdur Rahim; Md Ikram Hossain; Md Shahinoor Islam; Md Romzan Ali; Md Sadek Bacchu; Hiroki Waizumi; Tadahiro Komeda; Md Zaved Hossain Khan

doi:10.1016/j.heliyon.2023.e16506

Enhanced photocatalytic activity of Cu and Ni-doped ZnO nanostructures: A comparative study of methyl orange dye degradation in aqueous solution

Heliyon. 2023 May 22;9(6):e16506. doi: 10.1016/j.heliyon.2023.e16506. eCollection 2023 Jun.

Authors

Affiliations

¹ Department of Chemical Engineering, Jashore University of Science and Technology (JUST), Jashore 7408, Bangladesh.
² Department of Civil and Environmental Engineering, University of Alberta, Edmonton T6G 1H9, Alberta, Canada.
³ Department of Chemical Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka 1000, Bangladesh.
⁴ Research Expert, Daffodil International University (DIU), Dhaka 1312, Bangladesh.
⁵ Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aza-Aoba, Aoba-Ku, Sendai 9808578, Japan.
⁶ Institute of Multidisciplinary Research for Advanced Materials (IMRAM, Tagen), Tohoku University, 2-1-1, Katahira, Aoba-Ku, Sendai 980-0877, Japan.

Abstract

Heterogeneous photocatalysis has been considered one of the most effective and efficient techniques to remove organic contaminants from wastewater. The present work was designed to examine the photocatalytic performance of metal (Cu and Ni) doped ZnO nanocomposites in methyl orange (MO) dye degradation under UV light illumination. The wurtzite hexagonal structure was observed for both undoped/doped ZnO and a crystalline size ranging between 8.84 ± 0.71 to 12.91 ± 0.84 nm by X-ray diffraction (XRD) analysis. The scanning electron microscope (SEM) and energy dispersive X-ray (EDX) revealed the irregular spherical shape with particle diameter (34.43 ± 6.03 to 26.43 ± 4.14 nm) and ensured the purity of the individual elemental composition respectively. The chemical bonds (O-H group) and binding energy (1021.8 eV) were identified by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) results respectively. The bandgap energy was decreased from 3.44 to 3.16 eV when Ni dopant was added to the ZnO lattice. The comparative photocatalytic activity was observed in undoped and doped nanocomposites and found to be 76.31%, 81.95%, 89.30%, and 83.39% for ZnO, Cu/ZnO, Ni/ZnO, and Cu/Ni/ZnO photocatalysts, respectively, for a particular dose (0.210 g) and dye concentration (10 mg L^-1) after 180 min illumination of UV light. The photocatalytic performance was increased up to 94.40% with the increase of pH (12.0) whereas reduced (35.12%) with an increase in initial dye concentration (40 mg L^-1) using Ni/ZnO nanocomposite. The Ni/ZnO nanocomposite showed excellent reusability and was found 81% after four consecutive cycles. The best-fitted reaction kinetics was followed by pseudo-first-order and found reaction rate constant (0.0117 min^-1) using Ni/ZnO nanocomposite. The enhanced photodegradation efficiency was observed due to decreases in bandgap energy and the crystalline size of the photocatalyst. Therefore, Ni/ZnO nanocomposite could be used as an emerging photocatalyst to degrade bio-persistent organic dye compounds from textile wastewater.

Keywords: Methyl orange dye; Photocatalysis; Sol-gel method; Suspension reactor; UV light Illumination.