Structural characterization, morphology, optical and colorimetric properties of NiWO4 crystals synthesized by the co-precipitation and polymeric precursor methods

Oliveira, Yáscara Lopes de; Costa, Maria Joseíta dos Santos; Jucá, A. C. S.; Silva, L.K.R.; Longo, E.; Narayanasamy, Arul; Cavalcante, L. S.

doi:10.1016/j.molstruc.2020.128774

Cited by 31 publications

(21 citation statements)

References 68 publications

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“…To further analyze the molecular structure, Figure d,g illustrates how NiWO 4 is composed of zigzag metallic oxygen (M–O) chains. The Ni–O chain of the octahedral structure shares a pair of oxygen atoms with the W atom, contributing to NiWO 4 showing monocline phases at higher temperatures (800 °C) and better activity in catalytic reactions . The crystal structure of NiWO 4 is built via corner-shared [Ni 2 O 5 ] 6– layers, held together by W 6 + atoms.…”

Section: Resultsmentioning

confidence: 99%

NiWO₄ Microflowers on Multi-Walled Carbon Nanotubes for High-Performance NH₃ Detection

Yang

Deng

et al. 2021

ACS Appl. Mater. Interfaces

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NiWO4 microflowers with a large surface area up to 79.77 m2·g–1 are synthesized in situ via a facile coprecipitation method. The NiWO4 microflowers are further decorated with multi-walled carbon nanotubes (MWCNTs) and assembled to form composites for NH3 detection. The as-fabricated composite exhibits an excellent NH3 sensing response/recovery time (53 s/177 s) at a temperature of 460 °C, which is a 10-fold enhancement compared to that of pristine NiWO4. It also demonstrates a low detection limit of 50 ppm; the improved sensing performance is attributed to the porous structure of the material, the large specific surface area, and the p–n heterojunction formed between the MWNTs and NiWO4. The gas sensitivity of the sensor based on daisy-like NiWO4/MWCNTs shows that the sensor based on 10 mol % (MWN10) has the best gas sensitivity, with a sensitivity of 13.07 to 50 ppm NH3 at room temperature and a detection lower limit of 20 ppm. NH3, CO2, NO2, SO2, CO, and CH4 are used as typical target gases to construct the NiWO4/MWCNTs gas-sensitive material and study the research method combining density functional theory calculations and experiments. By calculating the morphology and structure of the gas-sensitive material NiWO4(110), the MWCNT load samples, the vacancy defects, and the influence law and internal mechanism of gas sensitivity were described.

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Section: Resultsmentioning

confidence: 99%

NiWO₄ Microflowers on Multi-Walled Carbon Nanotubes for High-Performance NH₃ Detection

Yang

Deng

et al. 2021

ACS Appl. Mater. Interfaces

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“…It is known that the optical properties of NiWO 4 are strongly dependent on its crystal structure. 7,12 Thus, it is clear that the electron−lattice coupling effect in NiWO 4 is another critical point for optimizing its performance.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Therefore, reducing the energy difference between the fundamental band and the Ni 2+ d–d transition bands is a critical issue for improving the optical properties of NiWO 4 . To date, considerable efforts have been made to improve the optical performance of NiWO 4 , such as dimensional reduction by different chemical preparation methods, local structural distortion by doping, and phase homologies by governing the compositions. ,− Despite significant progress, the fundamental band and the Ni 2+ d–d transition bands are usually overall blue-shifted or red-shifted, and their energy difference is still large, which is not conducive to improving its performance. It is known that the optical properties of NiWO 4 are strongly dependent on its crystal structure. , Thus, it is clear that the electron–lattice coupling effect in NiWO 4 is another critical point for optimizing its performance.…”

Section: Introductionmentioning

confidence: 99%

Effects of High Pressure on the Bandgap and the d–d Crystal Field Transitions in Wolframite NiWO₄

Zhou

Shao

et al. 2023

J. Phys. Chem. C

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The pressure effects on the optical and structural properties of NiWO4 have been studied experimentally and theoretically. The fundamental bandgap decreases with a pressure coefficient of −12.0 ± 0.2 meV/GPa. Meanwhile, the Ni2+ d–d transition energies increase at a rate of 7.4–14.8 meV/GPa. Therefore, the energy differences between the fundamental band and the Ni2+ d–d transition bands gradually decrease under pressure, which is beneficial to improve its optical performance. These optical phenomena are associated with structural variations. The shrinkage of the WO6 octahedron enhances the hybridization between the W 5d and O 2p orbitals, resulting in bandgap reduction. The pressure-induced enhancement of the NiO6 octahedral symmetry increases the crystal field splitting, thereby yielding increases in the Ni2+ d–d intraband transition energies. Besides, a pressure-induced structural phase transition is also observed around 20.0 GPa by both angle-dispersive synchrotron X-ray diffraction (ADXRD) and Raman experiments. This study provides valuable insight into the electron–lattice coupling of NiWO4 under compression and an effective way to modulate the electronic structure and optical properties of isomorphic wolframite materials.

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“…The band at 1365 cm −1 corresponds to the stretching modes of the W═O terminal bond present in each octahedron of WO 3 . [ 34 ] The band at 775 cm −1 arises from vibrations of WO 2 entity present in the W 2 O 8 groups. Karthiga et al [ 35 ] and Eranjaneya et al [ 36 ] reported similar type absorption bands for NiWO 4 .…”

Section: Resultsmentioning

confidence: 99%

Binder‐Free Synthesis of Mesoporous Nickel Tungstate for Aqueous Asymmetric Supercapacitor Applications: Effect of Film Thickness

et al. 2022

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However, the cost and the energy stored by these devices vary with the design, chemistry, and materials used to fabricate. The specific energy for batteries is comparatively more than the SCs and capacitors. [1,2] Due to outstanding cycle stability, greater power density, and rapid charge-discharge rate, SCs are some of the better optimistic contenders. [3,4] A significant drawback of SCs is that they are deficient in specific energy to fulfill the growing energy requirements for new-age energy storage equipment. [5,6] Nowadays, more research activities have been concentrated to enhance the specific energy of SCs without losing their specific power and cyclability. [7,8] The specific energy (E ¼ 0.5CV 2 ) can be raised by improving capacitance (C) and operating potential window (V ). Different electroactive materials with rages of capacitance values have been used to fabricate SCs. [9][10][11] Hence, the preparation of novel electrode materials possessing high specific capacitance and fabrication of asymmetric supercapacitors (ASCs) to overcome the issue of low cell potential can result in enhanced specific energy. [12,13] Metal tungstates have the general formula AWO 4 , where A is a divalent cation (A 2þ ¼ Ni, Fe, Mn, Cu, Co) that acts as a network modifier. The monoclinic crystal structure of metal tungstates (shown in Figure 1a,b) resembles with the crystal structure of metal sulfates. [14] Crystal structure formed by tungstate ion with bivalent metal ion forms tetrahedral coordination. However, due to the smaller radius of bivalent cations like nickel having ionic radius of less than 0.77 Å will perform well for the supercapacitors. In addition to this, the bimetallic nature of the metal tungstates helps to improve the energy storage capacity of materials compared to a single metal compound like NiO and WO 3 . Compared to nickel oxide and hydroxide, NiWO 4 have higher molecular mass, leading to lower theoretical capacitance. Higher cost of preparation due to addition of W in synthesis process can be considered a disadvantage. Metal oxides, including tungsten oxide and metal tungstates, show several advantages over other materials, such as low toxicity, low synthetic cost, high resistance against photocorrosion, and compatibility with up-scale. Normally, metal tungstate materials were tested for SC applications, [15] Li-ion battery, [16] electrocatalysis, [17] gas

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Structural characterization, morphology, optical and colorimetric properties of NiWO4 crystals synthesized by the co-precipitation and polymeric precursor methods

Cited by 31 publications

References 68 publications

NiWO₄ Microflowers on Multi-Walled Carbon Nanotubes for High-Performance NH₃ Detection

NiWO₄ Microflowers on Multi-Walled Carbon Nanotubes for High-Performance NH₃ Detection

Effects of High Pressure on the Bandgap and the d–d Crystal Field Transitions in Wolframite NiWO₄

Binder‐Free Synthesis of Mesoporous Nickel Tungstate for Aqueous Asymmetric Supercapacitor Applications: Effect of Film Thickness

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Structural characterization, morphology, optical and colorimetric properties of NiWO4 crystals synthesized by the co-precipitation and polymeric precursor methods

Cited by 31 publications

References 68 publications

NiWO4 Microflowers on Multi-Walled Carbon Nanotubes for High-Performance NH3 Detection

NiWO4 Microflowers on Multi-Walled Carbon Nanotubes for High-Performance NH3 Detection

Effects of High Pressure on the Bandgap and the d–d Crystal Field Transitions in Wolframite NiWO4

Binder‐Free Synthesis of Mesoporous Nickel Tungstate for Aqueous Asymmetric Supercapacitor Applications: Effect of Film Thickness

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Product

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NiWO₄ Microflowers on Multi-Walled Carbon Nanotubes for High-Performance NH₃ Detection

NiWO₄ Microflowers on Multi-Walled Carbon Nanotubes for High-Performance NH₃ Detection

Effects of High Pressure on the Bandgap and the d–d Crystal Field Transitions in Wolframite NiWO₄