Synthesis of WO3 nanorods by thermal oxidation technique for NO2 gas sensing application

Behera, Bhagaban; Chandra, Sudhir

doi:10.1016/j.mssp.2018.06.022

Cited by 90 publications

(28 citation statements)

References 41 publications

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“…Commercial WO 3 materials have very low response to various gases due to their low reactive sites. Therefore, synthesis of hierarchical nanostructures with higher specific surface area and porosity to improve gas sensitivity to a greater extent is still a hotspot of gas sensing research [ 36 ], which includes nanospheres [ 37 ], nanorods [ 38 ], nanoflakes [ 39 ], nanoflowers [ 40 ] and so on. WO 3 crystals are generally formed by corner and edge sharing of WO 6 octahedra, and evolve into the following crystal phase: monoclinic I (γ-WO 3 ), monoclinic II (ε-WO 3 ), triclinic (δ-WO 3 ), orthorhombic (β-WO 3 ), hexagonal (h-WO 3 ), tetragonal (α-WO 3 ), and cubic WO 3 [ 41 ].…”

Section: Introductionmentioning

confidence: 99%

Cr-Doped Urchin-Like WO3 Hollow Spheres: The Cooperative Modulation of Crystal Growth and Energy-Band Structure for High-Sensitive Acetone Detection

Ding

Wang

Guo

et al. 2020

Sensors

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Acetone is a biomarker in the exhaled breath of diabetic patients; sensitive and selective detection of acetone in human exhaled breath plays an important role in noninvasive diagnosis. Tungsten oxide (especially for γ-WO3) is a promising material for the detection of breath acetone. It is generally believed that the stable metastable phase of WO3 (ε-WO3) is the main reason for the improved response to acetone detection. In this work, pure and Cr-doped urchin-like WO3 hollow spheres were synthesized by a facile hydrothermal approach. Analyses of the resulting materials via X-ray photoelectron spectroscopy (XPS) and Raman confirmed that they are mainly composed by γ-WO3. The gas sensing performances of pure and Cr-doped WO3 to acetone were systematically tested. Results show that the sensor based on pure WO3 annealed at 450 °C has a high response of 20.32 toward 100 ppm acetone at a working temperature of 250 °C. After doped with Cr, the response was increased 3.5 times higher than the pure WO3 sensor. The pure and Cr-doped WO3 sensors both exhibit a tiny response to other gases, low detection limits (ppb-level) and an excellent repeatability. The improvement of gas sensing properties could be attributed to an optimized morphology of Cr-doped WO3 by regulating the crystal growth and reducing the assembled nanowires’ diameter. The increasing number of oxygen vacancy and the introduction of impurity energy level with trap effect after Cr doping would lead to the wider depletion layer as well as a better gas sensing performance. This work will contribute to the development of new WO3 acetone sensors with a novel morphology and will explain the increased response after Cr doping from a new perspective.

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Section: Introductionmentioning

confidence: 99%

Cr-Doped Urchin-Like WO3 Hollow Spheres: The Cooperative Modulation of Crystal Growth and Energy-Band Structure for High-Sensitive Acetone Detection

Ding

Wang

Guo

et al. 2020

Sensors

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“…Nevertheless, composite materials including metal oxide nanoparticles have drawn great attention due to their unique chemical and physical properties, which make them applicable for use in photocatalysis and gas sensing (Bittencourt et al, 2006; Guo et al, 2012; Chen et al, 2013). Among the existing metal oxides, tungsten oxide (WO 3 ) as an n-type semiconductor of a band gap of 2.5–2.8 eV owns important applications in numerous fields (Zeng et al, 2012; Gui et al, 2015; Behera and Chandra, 2018). WO 3 -based nanomaterials with various morphologies have been widely investigated for chemical gas sensors (Chu et al, 2017; Kaur et al, 2018; Gao et al, 2019) such as for detecting NH 3 , H 2 , and ethanol (Tsai et al, 2017; Chen et al, 2018; Morsy et al, 2018, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…Improved photocatalytic activities and gas sensing performances have been demonstrated for WO 3 -graphene composite. Recently, graphene-based composites have received considerable attention due to their potential applications in many useful fields including photocatalysis (Zhang et al, 2015; Luna et al, 2018) and gas sensors (Behera and Chandra, 2018). The enhanced performance was based on the composite high conductivity, large surface area and the P-type conductivity created due to adsorbed oxygen molecules localized on graphene structure.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Graphene Oxide Interspersed in Hexagonal WO3 Nanorods for High-Efficiency Visible-Light Driven Photocatalysis and NH3 Gas Sensing

et al. 2019

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WO3 nanorods and GO (at 1 wt% loading) doped WO3 were synthesized using a template free deposition-hydrothermal route and thoroughly characterized by various techniques including XRD, FTIR, Raman, TEM-SAED, PL, UV-Vis, XPS, and N2 adsorption. The nano-materials performance was investigated toward photocatalytic degradation of methylene blue dye (20 ppm) under visible light illumination (160 W, λ> 420) and gas sensing ability for ammonia gas (10–100 ppm) at 200°C. HRTEM investigation of the 1%GO.WO3 composite revealed WO3 nanorods of a major d-spacing value of 0.16 nm indexed to the crystal plane (221). That relevant plane was absent in pure WO3 establishing the intercalation with GO. The MB degradation activity was considerably enhanced over the 1%GO.WO3 catalyst with a rate constant of 0.0154 min−1 exceeding that of WO3 by 15 times. The reaction mechanism was justified dependent on electrons, holes and •OH reactive species as determined via scavenger examination tests and characterization techniques. The drop in both band gap (2.49 eV) and PL intensity was the main reason responsible for enhancing the photo-degradation activity of the 1%GO.WO3 catalyst. The later catalyst initiated the two electron O2 reduction forming H2O2, that contributed in the photoactivity improvement via forming •OH moieties. The hexagonal structure of 1%GO.WO3 showed a better gas sensing performance for ammonia gas at 100 ppm (Ra-Rg/Rg = 17.6) exceeding that of pure WO3 nanorods (1.27). The superiority of the gas-sensing property of the 1%GO.WO3 catalyst was mainly ascribed to the high dispersity of GO onto WO3 surfaces by which different carbon species served as mediators to hinder the recombination rate of photo-generated electron-hole pairs and therefore facilitated the electron transition. The dominancy of the lattice plane (221) in 1%GO.WO3 formed between GO and WO3 improved the electron transport in the gas-sensing process.

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“…It is clear from Table 1 that the WO 3 nanomesh material in this work exhibits the lowest detection limit at low operating temperature compared to other materials from Refs. [40][41][42][43][44]. In the absence of noble metal modification and ion doping, the intrinsic WO 3 nanomesh material exhibits high response and very low detection limit at low operating temperature.…”

Section: Gas Sensing Propertiesmentioning

confidence: 99%

Nanowires-assembled WO3 nanomesh for fast detection of ppb-level NO2 at low temperature

Liu

Ren

et al. 2020

J Adv Ceram

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Hierarchical WO 3 nanomesh, assembled from single-crystalline WO 3 nanowires, is prepared via a hydrothermal method using thiourea (Tu) as the morphology-controlling agent. Formation of the hierarchical architecture comprising of WO 3 nanowires takes place via Ostwald ripening mechanism with the growth orientation. The sensor based on WO 3 nanomesh has good electrical conductivity and is therefore suitable as NO 2 sensing material. The WO 3 nanomesh sensor exhibited high response, short response and recovery time, and excellent selectivity towards ppb-level NO 2 at low temperature of 160 ℃. The superior gas performance of the sensor was attributed to the high-purity hexagonal WO 3 with high specific surface area, which gives rise to enhanced surface adsorption sites for gas adsorption. The electron depletion theory was used for explaining the NO 2 -sensing mechanism by the gas adsorption/desorption and charge transfer happened on the surface of WO 3 nanomesh.

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Synthesis of WO3 nanorods by thermal oxidation technique for NO2 gas sensing application

Cited by 90 publications

References 41 publications

Cr-Doped Urchin-Like WO3 Hollow Spheres: The Cooperative Modulation of Crystal Growth and Energy-Band Structure for High-Sensitive Acetone Detection

Cr-Doped Urchin-Like WO3 Hollow Spheres: The Cooperative Modulation of Crystal Growth and Energy-Band Structure for High-Sensitive Acetone Detection

Synthesis of Graphene Oxide Interspersed in Hexagonal WO3 Nanorods for High-Efficiency Visible-Light Driven Photocatalysis and NH3 Gas Sensing

Nanowires-assembled WO3 nanomesh for fast detection of ppb-level NO2 at low temperature

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