NO sensing by single crystalline WO3 nanowires

Cai, Ze-Xing; Li, Huayao; Yang, Xubo; Guo, Xin

doi:10.1016/j.snb.2015.05.036

Cited by 116 publications

(45 citation statements)

References 55 publications

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“…These results are consistent with the XRD analysis. As depicted in Figure e, the XPS of reduced WO 3 /rGO sample confirm the W 5+ state exist after microwave treatment (the peaks at 34.19 and 36.53 eV correspond to W 5+ 4f 7/2 and W 5+ 4f 5/2 , respectively) . While the Ti 2p core level XPS spectra of pristine TiO 2 and reduced TiO 2 samples show an obvious binding energy shift (Figure f).…”

Section: Resultsmentioning

confidence: 62%

Microwave Combustion for Modification of Transition Metal Oxides

Wan

Gao

et al. 2016

Adv Funct Materials

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The introduction of oxygen vacancy for transition metal oxide is an effective method to tune their conductivity. Here, microwave combustion method is used to quickly synthesize reduced metal oxides and graphene hybrid composite in several minutes. Among these as-synthesized composites, the reduced orthorhombic Nb 2 O 5 and graphene oxide (rNb 2 O 5 /rGO) composite demonstrates great electrochemical performance with a reversible specifi c capacity of 726.2 C g −1 at 2 mV s −1 in organic electrolyte as well as a good capacity retention of 87% after 3000 cycles at 10 A g −1 . It is believed that this strategy can be a common route to quickly produce oxygen vacancy in oxides and satisfy much more application requirements even for the possibility of industrialization.

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Section: Resultsmentioning

confidence: 62%

Microwave Combustion for Modification of Transition Metal Oxides

Wan

Gao

et al. 2016

Adv Funct Materials

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“…High-resolution XPS spectra in the W4f and O1s regions for the WO3 NPs annealed at 550 ºC (see Figure S5 in SI) show two main W4f peaks (at 35.6 and 37.8 eV; doublet separation ∆ = 2.20 eV and an peak areas ratio 0.75), which are assigned to the W (VI) 4f7/2 and W (VI) 4f5/2 levels of W in +6 oxidation state in WO3, respectively [49,53]. The other two peaks with smaller intensities (at 34.3 and 36.6 eV) are assigned to W (V) 4f7/2 and W (V) 4f5/2 levels, respectively [54]; the presence of tungsten in a lower oxidation state, W (V) , is probably as a result of X-ray radiation reduction that may occur during XPS data acquisition. In the O1s region three peaks are observed: a main peak at 530.4 eV assigned to the lattice oxygen bonded to W [55], a peak at 531.5 eV due to -OH groups and possible C=O groups and a peak at 532.6 eV attributed to C-O bonds, probably from acetic acid residues [49,54]…”

Section: Figurementioning

confidence: 98%

Novel hybrid based on a poly[Ni( salen )] film and WO 3 nanoparticles with electrochromic properties

Nunes

Moura

Hillman

et al. 2017

Electrochimica Acta

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The strategy of combining electroactive polymers and inorganic nanomaterials has been widely explored in recent years in order to improve some of their properties, namely electrocatalysis and electrochromism. This report focuses on a new composite prepared through the electropolymerization of the transition metal complex ], designated as [1], in the presence of WO3 nanoparticles (NPs) and its electrochromic (EC) performance. The WO3 NPs were prepared using tungsten metal powder; their characterization indicated quasi-spherical morphology, high crystallinity and particle sizes in the range 30 -40 nm. The nanocomposite WO3@poly[1] films displayed similar electrochemical responses to those of pristine poly[1] films in LiClO4/CH3CN, but higher electroactive surface coverages, an advantage of NPs incorporation in the nanocomposite.The presence of the WO3 NPs in the poly[1] matrix was assessed by X-ray photoelectron spectroscopy and scanning electronic microscopy. The nanocomposite presented similar electronic spectra to those of poly [1], indicating that the electronic structure of the pristine film is maintained in the nanocomposite, but exhibited lower ε-values for bands associated with charge transfer transitions for high oxidised states, revealing an enhanced stability towards ligand over-oxidation.The WO3@poly[1] nanocomposite showed more favourable EC properties in LiClO4/CH3CN than the pristine film. For typical coverages (Γ = 0.06-0.10 µmol cm -2 ) the composite showed lower switching times (τ = 1.3 -3.6 s), higher optical contrast (∆T ≈ 31 %, an improvement of ca. 40 %) and better colouration efficiencies (in the range η = 104 -115 cm 2 C -1 , improvement of ca. 13 -22 %).(cathodic EC material) [23,24]. These properties make it an attractive "partner" for CPs (or other electroactive polymers) in hybrid materials for EC applications. In fact, several EC nanocomposites based in the incorporation of WO3 nanostructures into CP matrices, such as polyaniline (PANI) [23][24][25][26][27] and poly(3,4-ethylenedioxythiophene) (PEDOT)[28], have already been reported, exploiting the complementary EC attributes of WO3 and CPs. In general, CPs exhibit interesting optical properties, with rich colour changes due to their multiple redox states, but have low colour switching rates due to the slow transport of charge balancing counter ions ("dopants") into the polymer layer. On the other hand, metal oxide nanostructures have high surface-to-volume ratio and organized structures that facilitate ion/electron intercalation processes and promote switching reversibility [10,29]. Thus, the resultant nanocomposites promise the advantage of synergistic influence of the WO3 on the EC properties of conducting polymer, presenting improved EC properties with more satisfactory switching speeds and colouration efficiencies [23,25,27].The poly[M(salen)]-type films (M ≡ transition metal) are a particular class of electroactive metallopolymers, derived from metal salen complexes, recently studied by their interesting EC behavior [30,31]. Th...

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“…Very high response (≈nine times) for even low concentration of NO 2 (50 ppb) was recorded at moderate operating temperature of 150 °C. In another attempt, Cai et al were able to grow single crystalline orthorhombic WO 3 nanowires of diameter of 15–20 nm directly on FTO substrate by hydrothermal synthesis 22. These nanowires have shown their affinity toward NO sensing at an operating temperature of 300 °C with decent response and recovery time.…”

Section: Tungsten Chalcogenides and Their Gas Sensing Applicationsmentioning

confidence: 99%

Recent Progress in Chemiresistive Gas Sensing Technology Based on Molybdenum and Tungsten Chalcogenide Nanostructures

Jha

Bhat

2020

Adv Materials Inter

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bonding of transition metal and chalcogen atom and their crystal structure. Interestingly, all these compounds exist as layered material except tungsten oxide (WO 3 ) whose hydrated crystal (WO 3 .H 2 O) is layered in nature. [2,3] Each of these chalcogenides possesses unique features. Several micro and nanostructures of these chalcogenides have been synthesized in literature for various applications including gas sensors, biosensors, batteries, supercapacitor, photoelectrochemical and electrochromic devices. However, this review article will focus on gas sensing applications of these materials.Gas sensors play a crucial role in our life as they find applications ranging from monitoring indoor air quality to detecting highly toxic gases. Two important components of a gas sensing device are receptor and transducer. The receptor enables the chemical interaction with the target analyte molecule, which is further converted into analytical signal by the transducer. There are several transduction techniques available in gas sensing based on the physical or chemical change being measured. Broadly, they can be classified into six different classes based on sensing principles which is listed in Table 1.Chemiresistive devices have several advantages over other existing techniques. For example, the structure of these types of devices is very simple and it can be integrated with the current complementary metal oxide semiconductor (CMOS) technology. Even though, several advances have been made over last few years to improve sensing performance, the search for reliable and repeatable gas sensing element is an ongoing endeavor with lots of expectation from tungsten and molybdenum chalcogenides.After the rise of graphene, other layered materials have emerged as important functional materials for various applications of highest scientific values. Among these, layered transition metal dichalcogenides (TMDs) have a special presence as they cover whole class of materials, i.e., ranging from pure insulators to true metals. W and Mo chalcogenides are mostly semiconducting in ambient conditions and therefore, suitable for electronic application such as chemiresistive gas sensors. Though, layered TMDs (MX 2 M = Mo, and W and X = S, Se, and Te) have evolved expeditiously in a very short time, we simply cannot ignore metal oxide (particularly Mo-and W-based Chalcogens are oxygen family elements with oxygen having distinct properties than the other group members like sulfur, selenium, and tellurium. Tungsten and molybdenum chalcogenides that include mainly metal oxides (MO 3 ; M = Mo, and W) and metal dichalcogenides (MX 2 ; X = S, Se, and Te) are the most exciting class of inorganic materials. They have been widely investigated in various applications including lithium and sodium ion storage, supercapacitors, gas sensors, biosensors etc. due to their fascinating surface properties and ease of fabrication. Different class of nanostructures including 0D (nanoparticles, quantum dots), 1D (nanowires, nanotubes, nanoribbons, nanobelts etc.), a...

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NO sensing by single crystalline WO3 nanowires

Cited by 116 publications

References 55 publications

Microwave Combustion for Modification of Transition Metal Oxides

Microwave Combustion for Modification of Transition Metal Oxides

Novel hybrid based on a poly[Ni( salen )] film and WO 3 nanoparticles with electrochromic properties

Recent Progress in Chemiresistive Gas Sensing Technology Based on Molybdenum and Tungsten Chalcogenide Nanostructures

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