The role of pH on the vibrational, optical and electronic properties of the Zn Fe O compound synthesized via sol gel method

Soares, Adriano Santana; Castro-Lopes, S.; Cabrera-Baez, M.; Milani, Raquel Fernanda; Padrón-Hernández, E.; Farias, B.; Soares, J.M.; Gusmão, Suziete S.; Viana, Bartolomeu C.; Guerra, Y.; Oliveira, Cristieli Sérgio de Menezes; Peña-Garcia, R.

doi:10.1016/j.solidstatesciences.2022.106880

Cited by 29 publications

(5 citation statements)

References 109 publications

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“…The presence of polysaccharide structure is probably derived from the low calcination temperature that did not eliminate the organic parts. Lastly, the band in the range between 700 cm −1 and 400 cm −1 is associated with the vibration of the Zn–O bonds [ 55 , 57 ]. The spectra observed for pure and Er-doped ZnO samples exhibit remarkable similarity, mainly because the Er–O vibrations are situated at 569 and 550 cm −1 , overlapping with the Zn–O vibrations [ 27 ].…”

Section: Resultsmentioning

confidence: 99%

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

Silva,

Castro-Lopes,

Jerônimo

et al. 2024

Molecules

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We present a study on the green synthesis of undoped and Er-doped ZnO compounds using Mangifera indica gum (MI). A set of tests were conducted to assess the structure of the material. The tests included X-ray diffraction, Raman, and Fourier-transform infrared spectroscopy. Optical properties were studied using diffuse reflectance and photoluminescence. Morphological and textural investigations were done using SEM images and N2 adsorption/desorption. Furthermore, photocatalytic tests were performed with methylene blue (MB), yellow eosin (EY), and the pharmaceutical drug ibuprofen (IBU) under UV irradiation. The study demonstrated that replacing the stabilizing agent with Mangifera indica gum is an effective method for obtaining ZnO nanoparticles. Additionally, the energy gap of the nanoparticles exhibits a slight reduction in value. Photoluminescence studies showed the presence of zinc vacancies and other defects in both samples. In the photocatalytic test, the sample containing Er3+ exhibited a degradation of 99.7% for methylene blue, 81.2% for yellow eosin, and 52.3% for ibuprofen over 120 min. In the presence of methyl alcohol, the degradation of MB and EY dyes is 16.7% and 55.7%, respectively. This suggests that hydroxyl radicals are responsible for the direct degradation of both dyes. In addition, after the second reuse, the degradation rate for MB was 94.08%, and for EY, it was 82.35%. For the third reuse, the degradation rate for MB was 97.15%, and for EY, it was 17%. These results indicate the significant potential of the new semiconductor in environmental remediation applications from an ecological synthesis.

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Section: Resultsmentioning

confidence: 99%

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

Silva,

Castro-Lopes,

Jerônimo

et al. 2024

Molecules

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“…According to the literature, these bands point to the transitions from the ground level ( 4 I 15/2 ) to the excited states ( 4 F 5/2 ), ( 4 F 7/2 ) and ( 4 F 9/2 ) when dopant Er cations are inserted into the hexagonal structure [ 54 ]. Using the Kubelka–Munk model and Tauc’s plot, the band gap energy of the compound is estimated ( Figure 2 d) [ 55 ]. The calculated value (3.323 ± 0.001 eV) is in agreement with the value reported for ZnO bulk (3.35 eV) [ 49 ].…”

Section: Resultsmentioning

confidence: 99%

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

et al. 2023

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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.

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“…Furthermore, a clear increase in blue emission related to peaks located in the range of 443-466 nm is also seen upon increasing doping. All these data suggest an increase in the surface defect states for the doped samples since the peaks located in this range result from the near band-edge transition (NBE) as a consequence of the excitonic recombination of electrons located in states close to the edge of the layers conduction and valence [12,46,74,75].…”

Section: Investigation Of the Optical Properties Of The Zn 1−x Ni X O...mentioning

confidence: 96%

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

Lins,

Jerônimo,

Barbosa

et al. 2023

Molecules

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This work adopted a green synthesis route using cashew tree gum as a mediating agent to obtain Ni-doped ZnO nanoparticles through the sol–gel method. Structural analysis confirmed the formation of the hexagonal wurtzite phase and distortions in the crystal lattice due to the inclusion of Ni cations, which increased the average crystallite size from 61.9 nm to 81.6 nm. These distortions resulted in the growth of point defects in the structure, which influenced the samples’ optical properties, causing slight reductions in the band gaps and significant increases in the Urbach energy. The fitting of the photoluminescence spectra confirmed an increase in the concentration of zinc vacancy defects (VZn) and monovacancies (Vo) as Zn cations were replaced by Ni cations in the ZnO structure. The percentage of VZn defects for the pure compound was 11%, increasing to 40% and 47% for the samples doped with 1% and 3% of Ni cations, respectively. In contrast, the highest percentage of VO defects is recorded for the material with the lowest Ni ions concentration, comprising about 60%. The influence of dopant concentration was also reflected in the photocatalytic performance. Among the samples tested, the Zn0.99Ni0.01O compound presented the best result in MB degradation, reaching an efficiency of 98.4%. Thus, the recovered material underwent reuse tests, revealing an efficiency of 98.2% in dye degradation, confirming the stability of the photocatalyst. Furthermore, the use of different inhibitors indicated that •OH radicals are the main ones involved in removing the pollutant. This work is valuable because it presents an ecological synthesis using cashew gum, a natural polysaccharide that has been little explored in the literature.

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The role of pH on the vibrational, optical and electronic properties of the Zn Fe O compound synthesized via sol gel method

Cited by 29 publications

References 109 publications

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

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

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

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

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