Efficient Ni and Fe doping process in ZnO with enhanced photocatalytic activity: A theoretical and experimental investigation

Lemos, Samantha C.S.; Rezende, Thaís Karine de Lima; Assis, Marcelo; Romeiro, Fernanda da Costa; Peixoto, Diego Alves; Gomes, Eduardo de Oliveira; Jacobsen, G.M.; Teodoro, M. D.; Ferrari, Jefferson Luis; Longo, E.; Lima, Ronaldo Cintra

doi:10.1016/j.materresbull.2022.111849

Cited by 21 publications

(17 citation statements)

References 90 publications

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“…The elongated hexagonal morphology (a) was obtained by Amin et al by the hydrothermal method using different experimental parameters such as pH, precursor concentration, growth time, and temperature [ 67 ]. This morphology was also reported by some of us through the doping of ZnO with Ni and Fe to enhance its photocatalytic activity [ 68 ]. These results are clear-cut examples of how the reaction conditions and the synthesis methods can modulate the final morphology.…”

Section: Resultssupporting

confidence: 78%

Back to the Basics: Probing the Role of Surfaces in the Experimentally Observed Morphological Evolution of ZnO

et al. 2023

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Although the physics and chemistry of materials are driven by exposed surfaces in the morphology, they are fleeting, making them inherently challenging to study experimentally. The rational design of their morphology and delivery in a synthesis process remains complex because of the numerous kinetic parameters that involve the effective shocks of atoms or clusters, which end up leading to the formation of different morphologies. Herein, we combined functional density theory calculations of the surface energies of ZnO and the Wulff construction to develop a simple computational model capable of predicting its available morphologies in an attempt to guide the search for images obtained by field-emission scanning electron microscopy (FE-SEM). The figures in this morphology map agree with the experimental FE-SEM images. The mechanism of this computational model is as follows: when the model is used, a reaction pathway is designed to find a given morphology and the ideal step height in the whole morphology map in the practical experiment. This concept article provides a practical tool to understand, at the atomic level, the routes for the morphological evolution observed in experiments as well as their correlation with changes in the properties of materials based solely on theoretical calculations. The findings presented herein not only explain the occurrence of changes during the synthesis (with targeted reaction characteristics that underpin an essential structure–function relationship) but also offer deep insights into how to enhance the efficiency of other metal-oxide-based materials via matching.

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Section: Resultssupporting

confidence: 78%

Back to the Basics: Probing the Role of Surfaces in the Experimentally Observed Morphological Evolution of ZnO

et al. 2023

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“…In the third reuse, the photocatalytic response of the material is 21.3%. The decrease in the rate of degradation in reuse cycles can occur due to mass loss and the photocorrosion process of the ZnO when subjected to UV radiation [ 14 , 32 ].…”

Section: Resultsmentioning

confidence: 99%

“…Zinc oxide (ZnO) is a semiconductor that has been investigated for water purification, due to its physical and chemical stability, non-toxicity high sensitivity and wide band gap [ 12 , 13 , 14 , 15 ]. However, the rapid recombination of the electron–hole pair in ZnO strongly influences the photocatalytic activity [ 16 , 17 ].…”

Section: Introductionmentioning

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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“…As evidenced by the Wulff construction and TEM micrograph images, surface (100) prevails in the morphology of nanoparticles synthesized in ethanol, causing a significant decrease in its photocatalytic efficiency. RhB photocatalytic decomposition may be attributed to different kinetic models, such as the pseudo-first-order one, which is based on a simplified Langmuir–Hinshelwood model (eq ), or the pseudo-second-order one (eq ) ln ( C n / C 0 ) = prefix− k t 1 C normaln − 1 C 0 = k t where the kinetic rate constant ( k ) is determined from a linear fit to the data, t is the time, C 0 is the initial concentration, and C n is the concentration variation.…”

Section: Resultsmentioning

confidence: 99%

“…As evidenced by the Wulff construction and TEM micrograph images, surface (100) prevails in the morphology of nanoparticles synthesized in ethanol, causing a significant decrease in its photocatalytic efficiency. RhB photocatalytic decomposition may be attributed to different kinetic models, such as the pseudo-first-order one, which is based on a simplified Langmuir–Hinshelwood model (eq ), or the pseudo-second-order one (eq ) where the kinetic rate constant ( k ) is determined from a linear fit to the data, t is the time, C 0 is the initial concentration, and C n is the concentration variation.…”

Section: Resultsmentioning

confidence: 99%

The Relationship between Photoluminescence Emissions and Photocatalytic Activity of CeO₂ Nanocrystals

et al. 2023

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In this work, we focus on understanding the morphology and photocatalytic properties of CeO2 nanocrystals (NCs) synthesized via a microwave-assisted solvothermal method using acetone and ethanol as solvents. Wulff constructions reveal a complete map of available morphologies and a theoretical-experimental match with octahedral nanoparticles obtained through synthesis using ethanol as solvent. NCs synthesized in acetone show a greater contribution of emission peaks in the blue region (∼450 nm), which may be associated with higher Ce3+ concentration, originating shallow-level defects within the CeO2 lattice while for the samples synthesized in ethanol a strong orange-red emission (∼595 nm) suggests that oxygen vacancies may originate from deep-level defects within the optical bandgap region. The superior photocatalytic response of CeO2 synthesized in acetone compared to that of CeO2 synthesized in ethanol may be associated with an increase in long-/short-range disorder within the CeO2 structure, causing the E gap value to decrease, facilitating light absorption. Furthermore, surface (100) stabilization in samples synthesized in ethanol may be related to low photocatalytic activity. Photocatalytic degradation was facilitated by the generation of ·OH and ·O2 – radicals as corroborated by the trapping experiment. The mechanism of enhanced photocatalytic activity has been proposed suggesting that samples synthesized in acetone tend to have lower e′h· pair recombination, which is reflected in their higher photocatalytic response.

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Efficient Ni and Fe doping process in ZnO with enhanced photocatalytic activity: A theoretical and experimental investigation

Cited by 21 publications

References 90 publications

Back to the Basics: Probing the Role of Surfaces in the Experimentally Observed Morphological Evolution of ZnO

Back to the Basics: Probing the Role of Surfaces in the Experimentally Observed Morphological Evolution of ZnO

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

The Relationship between Photoluminescence Emissions and Photocatalytic Activity of CeO₂ Nanocrystals

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Efficient Ni and Fe doping process in ZnO with enhanced photocatalytic activity: A theoretical and experimental investigation

Cited by 21 publications

References 90 publications

Back to the Basics: Probing the Role of Surfaces in the Experimentally Observed Morphological Evolution of ZnO

Back to the Basics: Probing the Role of Surfaces in the Experimentally Observed Morphological Evolution of ZnO

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

The Relationship between Photoluminescence Emissions and Photocatalytic Activity of CeO2 Nanocrystals

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The Relationship between Photoluminescence Emissions and Photocatalytic Activity of CeO₂ Nanocrystals