Photoresponsive Activity of the Zn0.94Er0.02Cr0.04O Compound with Hemisphere-like Structure Obtained by Co-Precipitation

Abstract

In this work, a ZnO hemisphere-like structure co-doped with Er and Cr was obtained by the co-precipitation method for photocatalytic applications. The dopant’s effect on the ZnO lattice was investigated using X-ray diffraction, Raman, photoluminescence, UV-Vis and scanning electron microscopy/energy dispersive spectroscopy techniques. The photocatalytic response of the material was analyzed using methylene blue (MB) as the model pollutant under UV irradiation. The wurtzite structure of the Zn0.94Er0.02Cr0.04O compound presented distortions in the lattice due to the difference between the ionic radii of the Cr3+, Er3+ and Zn2+ cations. Oxygen vacancy defects were predominant, and the energy competition of the dopants interfered in the band gap energy of the material. In the photocatalytic test, the MB degradation rate was 42.3%. However, using optimized H2O2 concentration, the dye removal capacity reached 90.1%. Inhibitor tests showed that •OH radicals were the main species involved in MB degradation that occurred without the formation of toxic intermediates, as demonstrated in the ecotoxicity assays in Artemia salina. In short, the co-doping with Er and Cr proved to be an efficient strategy to obtain new materials for environmental remediation.

Green Synthesis of Er-Doped ZnO Nanoparticles: An Investigation on the Methylene Blue, Eosin, and Ibuprofen Removal by Photodegradation

“…In this instance, the Er 3+ ions resulted in a decrease in the lattice parameters’ values. This outcome could be attributed to Er 3+ ions replacing Zn 2+ ions within the ZnO hexagonal structure [ 11 ]. Because Er 3+ and Zn 2+ ions have different oxidation states, this substitution may lead to the creation of defects, such as cations vacancies, aligning with the principle of electrical neutrality within the ZnO crystal [ 43 ].…”

“…During the synthesis of the compound, structural changes occurred, as identified by XRD, FTIR, Raman, and PL characterizations… [ 42 , 89 , 90 ]. These changes have altered the properties of the material, making it more efficient in photocatalytic action [ 11 , 40 , 54 , 66 , 81 ]. This improvement may have been caused by the dopant insertion or by the synthesis with the replacement of the stabilizing agent by gum.…”

“…[42,89,90]. These changes have altered the properties of the material, making it more efficient in photocatalytic action [11,40,54,66,81]. This improvement may have been caused by the dopant insertion or by the synthesis with the replacement of the stabilizing agent by gum.…”

“…Zinc oxide (ZnO) is an n-type of semiconductor that has been extensively studied due to its unique properties such as thermal and optical stability, adequate band gap, large excitation binding energy, and affordable cost. These properties make it appropriate for use in various applications such as solar cells, energy storage, optoelectronics and electronic devices [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], and photocatalysis [ 8 , 9 , 10 , 11 ]. Additionally, ZnO nanoparticles are non-toxic and biocompatible, making them suitable for various biological applications [ 12 , 13 , 14 ], which is why they are receiving attention in different research fields.…”

Facile Synthesis of Ni-Doped ZnO Nanoparticles Using Cashew Gum: Investigation of the Structural, Optical, and Photocatalytic Properties

“…The issue of contamination is particularly complicated because of the challenges involved in eliminating pollutants. One such pollutant, which is cationic and contains a heterocyclic aromatic chain that is difficult to break down, is resistant to natural degradation and persists in the environment [12].…”