Metastable γ-Bi2O3 tetrahedra: Phase-transition dominated by polyethylene glycol, photoluminescence and implications for internal structure by etch

Wang, Yi; Li, Yunling

doi:10.1016/j.jcis.2015.05.001

Cited by 28 publications

(41 citation statements)

References 44 publications

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“…Figure 4a presents the RT PL spectra (open dots) of γ-Bi 2 O 3 showing a strong and broad emission from~350 to 900 nm centered at around 700 nm. The deconvolution of the PL spectra (black line) was carried out using the sum of four emission bands centered at 394, 487, 588, and 701 nm (Table 3), which agrees with the reported spectra in [26]. A schematic energy level diagram for the Bi 3+ valence state is shown in Figure 4b.…”

Section: Photoluminescence Spectroscopysupporting

confidence: 78%

“…However, the observed oxygen deficiency from EDS, vacancies at O(2) sites from PXRD, a red-shift, and a line-width broadening from Raman spectra suggest that V O density defect levels could lead to intense red-band emission. Wang et al also reported similar red-band emission centered at 705 nm and attributed to a high density of V O on the surface of γ-Bi 2 O 3 [26]. Kumari et al also reported emission maxima between 660 and 770 nm from composite α/β-Bi 2 O 3 attributed to defect/impurity states induced by oxygen vacancies present in the nanostructures [47].…”

Section: Photoluminescence Spectroscopymentioning

confidence: 76%

“…It is also utilized in analyzing point defects such as cation and anion vacancies [35]. Similarly, PL spectroscopies can be used as a powerful tool in identifying defects, particularly for V O in metal oxides [26,36]. Our experimental results indicate the formation of vacancies at B(1) and O(2) sites during annealing, of which the former could be intrinsic and later play a decisive role in the RT stabilization of γ-Bi 2 O 3 .…”

Section: Introductionmentioning

confidence: 77%

“…However, according to theoretical calculations, the introduction of V O at O(3) sites makes the crystal structure of γ-Bi 2 O 3 further distorted, due to which it loses its I23 symmetry. Therefore, as observed from PXRD analysis, it is possible that during the annealing process, a high density of V O defects could have been formed in γ-Bi 2 O 3 at octahedra O(2) sites (in the internal Bi-O framework) such that the excess defects may have prevented the transformation from BCC to monoclinic α-Bi 2 O 3 phase, which, in turn, resulted in the formation of RT stabilized γ-Bi 2 O 3 NPs [26]. In conclusion, RT stabilized γ-Bi 2 O 3 NPs with a mean diameter of 90 nm were successfully prepared at the expense of Bi NPs simply by annealing at 550 • C for a duration of 2 h in an ambient atmosphere.…”

Section: Discussionmentioning

confidence: 99%

“…Hereof, in recent decades, various physical and chemical methods have been introduced for the synthesis of RT stabilized γ–Bi 2 O 3 nanostructures with various morphologies [ 1 , 9 ]. Versatile forms of nanostructures could be obtained either by heating the mixture at low temperature (40–90 °C) [ 2 , 3 , 24 , 25 , 26 , 27 , 28 , 29 ] or in some methods at high temperature (300–800 °C) [ 4 , 6 , 7 , 30 , 31 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

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Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Gandhi

Cheng

2020

Nanomaterials

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We report the synthesis of room temperature (RT) stabilized γ–Bi2O3 nanoparticles (NPs) at the expense of metallic Bi NPs through annealing in an ambient atmosphere. RT stability of the metastable γ–Bi2O3 NPs is confirmed using synchrotron radiation powder X-ray diffraction and Raman spectroscopy. γ–Bi2O3 NPs exhibited a strong red-band emission peaking at ~701 nm, covering 81% integrated intensity of photoluminescence spectra. Our findings suggest that the RT stabilization and enhanced red-band emission of γ‒Bi2O3 is mediated by excess oxygen ion vacancies generated at the octahedral O(2) sites during the annealing process.

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Section: Photoluminescence Spectroscopysupporting

confidence: 78%

Section: Photoluminescence Spectroscopymentioning

confidence: 76%

Section: Introductionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Gandhi

Cheng

2020

Nanomaterials

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Photodegradation Attenuated Oscillation:A Novel Photocatalytic Characteristic for the Polymetallic Oxide Semiconductor Porous Materials with Energy Bandgap Gradient

et al. 2021

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Samples of metal oxide SnO2 and its composite SnO2/Bi2O3, ploymetallic oxides SnO2/Bi2O3/CdO, SnO2/Bi2O3/Fe2O3, and SnO2/Bi2O3/CdO/Fe2O3 powder materials were successfully prepared by a simple solid‐state reaction method at room temperature using sodium benzenesulfonate (SBS) surfactant as template. The synthesized powder materials were characterized by X‐ray diffraction (XRD), UV‐vis diffuse reflectance spectrum (UV‐Vis), scanning electron microscopy/energy dispersive X‐ray (SEM/EDX), infrared spectroscopy (IR), X‐ray photoelectron spectroscopy (XPS), N2 adsorption‐desorption and the migration rate testing of charges. Moreover, the adsorption characteristic and photodegradation performance of methyl blue (MB, co=100 mg/L) on the materials were investigated. The results show that the degradation rate (94.2 %) of MB on the SnO2/Bi2O3/CdO/Fe2O3 nanomaterial is the highest than that of the other materials within 10 min under the visible‐light irradiation. After that, the photodegradation rate of MB on the as‐prepared SnO2/Bi2O3/CdO, SnO2/Bi2O3/Fe2O3 and SnO2/Bi2O3/CdO/Fe2O3 semiconductor materials with energy band gap gradient generates the novel phenomena of photo‐ degradation attenuated oscillation but absent for the SnO2/Bi2O3 and SnO2 materials. It may be originated from the presence of the phase‐transitions of α‐Bi2O3 and β‐Bi2O3, the change ratio of Fe3+ and Fe2+ in the photocatalytic process, and the characteristic adsorption of MB molecular groups by the different metal oxides. This provides new ideas for future inspiring continued research on this emerging class of mixed metal oxides semiconductors and thereby enables innovations.

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Epitaxial Growth of 2D Ultrathin Metastable γ‐Bi₂O₃ Flakes for High Performance Ultraviolet Photodetection

Wang

et al. 2021

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Although UV photodetectors based on a few kinds of 2D wide bandgap semiconductors have been investigated, their low detection capability still hinders the practical application. [18][19] For example, wide bandgap h-BN has been developed for UV detection, but exhibits a poor performance with responsivity of 0.1 mA W −1 and detectivity of 2.4 × 10 8 Jones. [19] Therefore, it is urgent to develop 2D materials with suitable bandgap, excellent light-matter interaction and high stability for high-performance UV detection.Bi 2 O 3 is a semiconductor with many intriguing properties, such as wide bandgap, excellent light sensitivity, environmental stability, nontoxic and elemental abundance, exhibiting great potential for UV detection. [16][17][18][19][20] There are four main crystal phases for Bi 2 O 3 , including monoclinic (α), [20][21] tetragonal (β), [22] body-centered cubic (γ), [23] and face cubic (δ). [24] Among them, γ-Bi 2 O 3 is a metastable semiconductor at high temperature and has been proved to exhibit excellent performance in the fields such as photocatalysis and photoelectrochemistry. [25][26] More importantly, γ-Bi 2 O 3 possesses a relatively wide bandgap of 2.9 eV and high absorption in the UV region compared with other three phases, [23,[27][28] and thus enabling it great potential for UV detection. Currently, mostly reported γ-Bi 2 O 3 structures are synthesized via liquid-based methods which inevitably introduce various organic impurities, and meanwhile, the size is usually limited to several nanometers, hindering their large-scale application in photoelectronic devices. [23,25,27] With regards to other methods, for instance, annealing of α-Bi 2 O 3 film or thermal oxidization of Bi nanoparticles, could also obtain γ-Bi 2 O 3 structure in nanoscale. [29][30] However, the obtained samples are usually polycrystalline, of which the grain boundaries will affect its intrinsic photoelectrical performance. To the best of our knowledge, it is still challenging to obtain ultrathin 2D γ-Bi 2 O 3 flakes with high quality to meet the requirements of ideal photoelectronic devices.Chemical vapor deposition (CVD) method has been widely used for the growth of ultrathin 2D flakes with high quality and accurately controlled morphology and size of the materials. However, it is still difficult to synthesize 2D γ-Bi 2 O 3 flakes through conventional CVD methods owing to the intrinsic isotropic chemical bonds in the nonlayered γ-Bi 2 O 3 crystal structure. Besides, the mixed phase and metastable nature of γ-Bi 2 O 3 Ultraviolet detection is of great significance due to its wide applications in the missile tracking, flame detecting, pollution monitoring, and so on. The nonlayered semiconductor γ-Bi 2 O 3 is a promising candidate toward highperformance UV detection due to the wide bandgap, excellent light sensitivity, environmental stability, nontoxic and elemental abundance properties. However, controllable preparation of ultrathin 2D γ-Bi 2 O 3 flakes remains a challenge, owing to its nonlayered structure, metastable natu...

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Metastable γ-Bi2O3 tetrahedra: Phase-transition dominated by polyethylene glycol, photoluminescence and implications for internal structure by etch

Cited by 28 publications

References 44 publications

Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Photodegradation Attenuated Oscillation:A Novel Photocatalytic Characteristic for the Polymetallic Oxide Semiconductor Porous Materials with Energy Bandgap Gradient

Epitaxial Growth of 2D Ultrathin Metastable γ‐Bi₂O₃ Flakes for High Performance Ultraviolet Photodetection

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Metastable γ-Bi2O3 tetrahedra: Phase-transition dominated by polyethylene glycol, photoluminescence and implications for internal structure by etch

Cited by 28 publications

References 44 publications

Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Photodegradation Attenuated Oscillation:A Novel Photocatalytic Characteristic for the Polymetallic Oxide Semiconductor Porous Materials with Energy Bandgap Gradient

Epitaxial Growth of 2D Ultrathin Metastable γ‐Bi2O3 Flakes for High Performance Ultraviolet Photodetection

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Resources

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Epitaxial Growth of 2D Ultrathin Metastable γ‐Bi₂O₃ Flakes for High Performance Ultraviolet Photodetection