The particle size-dependent optical band gap and magnetic properties of Fe-doped CeO2 nanoparticles

El-Hagary, M.; Shaaban, E.R.; Moustafa, S.H.; Gad, G. M. A.

doi:10.1016/j.solidstatesciences.2019.03.005

Cited by 84 publications

(23 citation statements)

References 53 publications

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“…Moreover, the red shift was found to be larger for MWINTs with smaller diameters 19 and for IFs containing more inner layers with smaller diameters, 13 which is opposite to the observed trend in CNTs with atomically thick layers, 44 and nonlayered NPs. [45][46][47] This observation was confirmed by theoretical calculations exhibiting a sustainable increase in strain energy for the bent layers with a decrease in diameter. 22,26 The SWINTs in this study have smaller diameters (3-7 nm) than MWINTs with 60-80 nm external and 20-30 nm internal diameters.…”

Section: Measurementssupporting

confidence: 65%

Cathodoluminescence in single and multiwall WS2 nanotubes: Evidence for quantum confinement and strain effect

Ghosh

Brüser

Kaplan‐Ashiri

et al. 2020

Applied Physics Reviews

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For nanoparticles with sub-10 nm diameter, the electronic bandgap becomes size dependent due to quantum confinement; this, in turn, affects their electro-optical properties. Thereby, MoS 2 and WS 2 monolayers acquire luminescent capability, due to the confinement-induced indirect-to-direct bandgap transition. Rolling up of individual layers results in single wall inorganic nanotubes (SWINTs). Up to the present study, their luminescence properties were expected to be auspicious but were limited to theoretical investigations only, due to the scarcity of SWINTs and the difficulties in handling them. By optimizing the conditions in the plasma reactor, relatively high yields of WS 2 SWINTs 3-7 nm in diameter were obtained in this work, compared to previous reports. A correlative approach, transmission electron microscopy coupled with a scanning electron microscope, was adapted to overcome handling obstacles and for testing individual nanotubes by lowtemperature cathodoluminescence. Clear cathodoluminescence spectra were obtained from WS 2 -SWINTs and compared with those of WS 2 multiwall nanotubes and the corresponding bulk material. Uniquely, the optical properties of INTs acquired from cathodoluminescence were governed by the opposite impact from quantum size effect and strain in the bent triple S-W-S layers. The experimental findings were confirmed by the Density Functional and Time-Dependent Density Functional theoretical modeling of monolayer and bilayer nanotubes of different chiralities and diameters. This study provides experimental evidence of the quantum confinement effect in WS 2 SWINTs akin to WS 2 monolayer. The ability to tune the electronic structure with morphology or number of layers may be exploited toward photoelectrochemical water splitting with WS 2 catalysts, devising field effect transistors, photodetectors, and so on.

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Section: Measurementssupporting

confidence: 65%

Cathodoluminescence in single and multiwall WS2 nanotubes: Evidence for quantum confinement and strain effect

Ghosh

Brüser

Kaplan‐Ashiri

et al. 2020

Applied Physics Reviews

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“…Here, we might infer about crystallite of Cu, Co and Fe oxides has nano size, who was showed by Scherrer equation, although UV-Vis absorption spectra lead an interpretation of big size particle behavior structure. It is important let clear that crystallite size does not mean same particle size [7,30]. While it does not precisely size particle of three catalyst, is import recognize that data shows near estimates between them, who catalytic contributions may come from only electronic environment properties of each metal.…”

Section: Resultsmentioning

confidence: 96%

“…Catalysts spectra shows a broad and strong absorption the UV-Vis in 350-750 nm range for the three catalysts, it may be a strong color consequence of them. Some studies have presented that nanoparticle size effect may influence the band gap of semiconductors, which generally decrease when the size of the nanoparticle increases [30]. Furthermore, band gap values almost trends zero electron-volt when nanoparticles are found in a big size or a thick film [31].…”

Section: Resultsmentioning

confidence: 99%

Redox effects in Cu, Co or Fe in oxides nanocrystals with high catalytic activity for the acetonitrile combustion

2020

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The cobalt, copper and iron oxides were investigated in selective catalytic combustion (SCC) of acetonitrile toward N 2 in gas phase. Catalysts were characterized by physical-chemical technics like XRD, H 2-TPR, DRS UV-Vis, whose confirmed crystalline phases of CuO, Co 3 O 4 and Fe 2 O 3. Thermodynamic stability of crystalline phase from metal oxides ruled important contributions in redox properties and become able to compare clearly the catalytic activity of the three catalyst. Relationship between H 2-TPR analysis and catalytic results obtained showed great relevance to understand how metal oxide works on reaction, who were related to easy redox process involved. SCC studies were carried out with range of 100-600 °C and Co 3 O 4 showed best activity (100% conversion at 570 °C) and high selectivities to N 2 and CO 2 starting in lower temperature. Byproducts from nitrogen-compounds were observed in low quantities for all catalysts.

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“…Later, the properties of CeO 2 have been developed by doping transition metals and searching the candidate material, which has great potential for applications in spintronic and multifunctional electronic devices [14][15][16][17][18][19]. The structural and physical properties of the CeO 2 doped with Fe have been investigated by previous studies [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Fe-doped effects on phase transition and electronic structure of CeO2 under compressed conditions from ab initio calculations

et al. 2021

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Ab initio study of high-pressure phase transition and electronic structure of Fe-doped CeO2 with Fe concentrations of 3.125, 6.25, and 12.5 at% has been reported. At a constant-pressure consideration, the lattice constants and the volume of the supercell were decreased with an increasing concentration of Fe. The average bond length of Fe–O is lower than that of Ce–O. As a result, Fe doping induces the reduced volume of the cell, which is in good agreement with previous experiments. At high pressure (~ 30 GPa), it was found that the transition pressure from the fluorite to the cotunnite orthorhombic phase decreases at a higher concentration of Fe, indicating that the formation energy of the compound is induced by Fe-doping. Furthermore, compression leads to interesting electronic properties too. Under higher pressures, the bandgap increases in the cubic structure under compression and then suddenly plummets after the transition to the orthorhombic phase. The 3d states of Fe mainly induced the impurity states in the bandgap. In both the undoped and Fe-doped systems, the bandgap increased in the cubic phase at high pressure, while the gap and p-d hybridization decrease in the orthorhombic phase.

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The particle size-dependent optical band gap and magnetic properties of Fe-doped CeO2 nanoparticles

Cited by 84 publications

References 53 publications

Cathodoluminescence in single and multiwall WS2 nanotubes: Evidence for quantum confinement and strain effect

Cathodoluminescence in single and multiwall WS2 nanotubes: Evidence for quantum confinement and strain effect

Redox effects in Cu, Co or Fe in oxides nanocrystals with high catalytic activity for the acetonitrile combustion

Fe-doped effects on phase transition and electronic structure of CeO2 under compressed conditions from ab initio calculations

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