Effect of the amapá-latex chelating agent contents on the microstructure and photocatalytic properties of ZnO nanoparticles

Matos, Robert Saraiva; Attah-Baah, John M.; Monteiro, Michael Douglas Santos; Costa, B. F. O.; Macêdo, M.A.; Silva, R.S.; Filho, Henrique Duarte da Fonseca; Oliveira, Rosane Maria Pessoa Betânio; Ferreira, Nilson S.

doi:10.1016/j.jmrt.2022.12.119

“…where Eg is a coating material band gap value, Eg SnO2 , Eg ZnO and Eg Fe2O3 are band gap values of SnO2, ZnO and Fe2O3, respectively. The substitution of molar ratios of oxides and their band gap values (Eg ZnO ~3.37 eV [33,44,46], Eg SnO2 ~3.6 eV [33], Eg Fe2O3 = 2.0 eV [38]) into Equation (2) gives Eg (ZnO-SnO2-Fe2O3) = 3.33 eV that is less than the value obtained from the spectral measurements (3.44 eV). This fact can be related to some deviation of the parameter b from 0 and to the small size of the semiconductor crystals in the coating and the effect of quantum confinement on them.…”

Section: Sem Analysismentioning

confidence: 84%

“…Photocatalytic materials are used in many different practical applications (water and air purification, sensors, water splitting, etc.) and are the object of intensive investigations [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Many oxide semiconductor materials are effective photocatalysts, demonstrate antibacterial activity and have an excellent thermal stability and chemical durability.…”

Section: Introductionmentioning

confidence: 99%

“…Ceramic materials (powders and coatings) based on ZnO are very effective photocatalysts [2][3][4][5][6][7][8][9][10][11][12][13][14] which have been successfully tested in industrial conditions [1]. Modification of the ZnO ceramic materials using other oxides additions provides a significant enhancement to its photocatalytic and bactericidal characteristics [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…Chemical composition, structure and morphology of photocatalysts determine the spectral diapason of the light which can excite a semiconductor material, its specific surface area, adsorption properties and photocatalytic activity. It was found [2,[6][7][8][9] that materials consisting of semiconductor nanoparticles with specific shapes, such as nanorods, nanowires and "flowers", exhibit high photocatalytic properties.…”

Section: Introductionmentioning

confidence: 99%

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Ceramic ZnO-SnO2-Fe2O3 Powders and Coatings -Effective Photogenerators of Reactive Oxygen Species

Khomutinnikova

¹

,

Evstropiev

²

,

Meshkovskiĭ

³

et al. 2023

Ceramics

5

0

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Ceramic ZnO-SnO2-Fe2O3 powders and transparent coatings on glasses prepared using the non-isothermal polymer-salt method demonstrate a strong ability to generate chemically active oxygen species under UV and visible irradiation. Crystal structures and morphologies of these materials were studied using the XRD and the SEM analysis. It was found that there are significant differences in the crystal structure of ceramic powders and thin coatings. The powders consist of randomly oriented oxide nanocrystals of size ~47 nm. The strong orientation of the ZnO nanocrystals due to their interaction with the glass substrate is observed in the coating structure. Experimental data show that thin ceramic coatings are transparent (~90%) in the visible spectral range and the band gap of the ceramic material is 3.44 eV. The band gap value of this multi-component ceramic material is described sufficiently using Verlag’s law. Ceramic powders and coatings demonstrate the intensive photogeneration of reactive oxygen species, both in liquid and air. High photocatalytic activity of ZnO-SnO2-Fe2O3 ceramic coatings and powders was observed upon the oxidation of the diazo dye, Chicago Sky Blue. In the presence of transparent photocatalytic coating, the value of the constant rate of the dye photodecomposition was high (k = 0.056 min−1). It was found that, in spite of their short life time, photogenerated reactive oxygen species demonstrate the ability to decompose dye molecules located up to a distance of 0.5 mm from the surface of ceramic coating. Obtained experimental results suggest that the prepared ceramic materials are promising for different practical applications of the photocatalytic materials.

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“…The diameters of ZnO range from 10 to 20 nm, while the diameter of Cu NPs is roughly 10 nm, respectively. These nanoparticles are further identified by the d spacing of fringes, with 0.283 nm for ZnO (100) [44] and 0.207 nm for Cu (111), [45] respectively. The electron paramagnetic resonance (EPR) results (Figure 3c) show a sharp peak for the sample before the reaction, which is owing to I = 3/2 of Cu 2 + , so CuO hyperfine structure (g // = 2.27, A // � 90 G) can be observed by EPR spectra, which agrees with the distorted octahedral coordination of Cu 2 + ions in CuO clusters.…”

Section: Characterizationsmentioning

confidence: 99%

Effective Activation of Strong C−Cl Bonds for Highly Selective Photosynthesis of Bibenzyl via Homo‐Coupling

Yang

¹

,

Li

²

,

Lu

³

et al. 2023

View full text Add to dashboard Cite

Carbon‐carbon coupling of organic halides as an important process in organic synthesis has been successfully achieved in homogeneous catalysis, while the dependence on rare noble metals, complicated metal‐complex and poor catalyst stability and recyclability, need to be tackled. The past few years have witnessed heterogeneous photocatalysis as green and novel methods for organic synthesis processes. However, the study on C–C coupling of chloride substrates is very limited due to the extremely high bond energy of C–Cl bond (327 kJ mol‐1). Here, we report a robust heterogeneous photocatalyst (Cu/ZnO) to drive the homo‐coupling of benzyl chloride with high efficiency, which achieves an unprecedented high selectivity of bibenzyl (93%) and yield rate of 92% at room temperature. Moreover, this photocatalytic process can be applied to 10 benzyl chlorides with high yields. With detailed characterisation (XPS, EPR, TPD) and DFT calculation, the high selectivity is attributed to the enhanced adsorption of reactants, stabilisation of intermediates (benzyl radicals) for the selective coupling by the Cu loading and the moderate oxidation ability of ZnO support, besides the promoted charge separation and transfer by Cu species. Therefore, this work offers a new route to highly selective synthesise bibenzyl from chloride substrates by a stable heterogeneous system.

show abstract

Effective Activation of Strong C−Cl Bonds for Highly Selective Photosynthesis of Bibenzyl via Homo‐Coupling

Yang

¹

,

Li

²

,

Lu

³

et al. 2023

Angewandte Chemie

1

0

View full text Add to dashboard Cite

Carbon‐carbon coupling of organic halides as an important process in organic synthesis has been successfully achieved in homogeneous catalysis, while the dependence on rare noble metals, complicated metal‐complex and poor catalyst stability and recyclability, need to be tackled. The past few years have witnessed heterogeneous photocatalysis as green and novel methods for organic synthesis processes. However, the study on C–C coupling of chloride substrates is very limited due to the extremely high bond energy of C–Cl bond (327 kJ mol‐1). Here, we report a robust heterogeneous photocatalyst (Cu/ZnO) to drive the homo‐coupling of benzyl chloride with high efficiency, which achieves an unprecedented high selectivity of bibenzyl (93%) and yield rate of 92% at room temperature. Moreover, this photocatalytic process can be applied to 10 benzyl chlorides with high yields. With detailed characterisation (XPS, EPR, TPD) and DFT calculation, the high selectivity is attributed to the enhanced adsorption of reactants, stabilisation of intermediates (benzyl radicals) for the selective coupling by the Cu loading and the moderate oxidation ability of ZnO support, besides the promoted charge separation and transfer by Cu species. Therefore, this work offers a new route to highly selective synthesise bibenzyl from chloride substrates by a stable heterogeneous system.

show abstract

Effect of the amapá-latex chelating agent contents on the microstructure and photocatalytic properties of ZnO nanoparticles

Cited by 10 publications

References 94 publications

Ceramic ZnO-SnO2-Fe2O3 Powders and Coatings -Effective Photogenerators of Reactive Oxygen Species

Ceramic ZnO-SnO2-Fe2O3 Powders and Coatings -Effective Photogenerators of Reactive Oxygen Species

Effective Activation of Strong C−Cl Bonds for Highly Selective Photosynthesis of Bibenzyl via Homo‐Coupling

Effective Activation of Strong C−Cl Bonds for Highly Selective Photosynthesis of Bibenzyl via Homo‐Coupling

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