Де використовується V2O5

a School of Mechanical Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
E-mail: [email protected], [email protected]

b School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China

Abstract

As an important part of lithium-ion batteries, the cathode material can directly affect the performance of lithium-ion batteries. However, with the increasing demand for high-energy and high-power devices, the energy and power density of electrode materials need to be further improved. Among all metal oxides, vanadium pentoxide (V₂O₅) is regarded as a promising candidate to serve as a cathode material for LIBs due to its high theoretical capacity. Herein, a thorough survey of the synthesis of V₂O₅-based nanomaterials with various structures and chemical compositions and their application as positive electrodes for LIBs is provided. This review covers V₂O₅ with different morphologies ranging from 1D nanorods/nanowires/nanotubes/nanofibers/nanobelts, to 2D nanosheets, and to 3D hollow and porous nanostructures. Nanocomposites consisting of V₂O₅ and different carbonaceous supports, e.g., amorphous carbon, carbon nanotubes, and graphene, are also investigated. The cation-doped V₂O₅ samples as the cathode material for LIBs are briefly discussed as well. The aim of this review is to provide an in-depth and rational understanding of how the electrochemical properties of V₂O₅-based cathodes can be effectively enhanced by achieving proper nanostructures with optimized chemical composition.

Vanadium Pentoxide (V₂O₅): Their Obtaining Methods and Wide Applications

Transition Metal Compounds – Synthesis, Properties, and Application

Edited by Sajjad Haider and Adnan Haider

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Abstract

The first synthesis of pentoxide vanadium (V2O5) as gel completed 135 years in 2020. Since its first synthesis, the V2O5 has attracted attention over the years in different areas in science and technology. There are several possibilities to obtain V2O5 resulting in different structures. Among these methods, it is possible to mention the sol–gel, hydrothermal/solvothermal synthesis, electrospinning, chemical vapor deposition (CVD), physical vapor deposition (PVD), template-based methods, reverse micelle techniques, Pechini method and electrochemical deposition that can be considered as the great asset for its varied structures and properties. Progress towards obtaining of different structures of V2O5, and phases have been resulted in lamellar structure with wide interlayer spacing, good chemical and thermal stability and thermoelectric and electrochromic properties. Throughout this advancement, its performance for industrial applications have made a strong candidate in electrochromic devices, photovoltaic cell, reversible cathode materials for Li batteries, supercapacitor, among others. This chapter will be to assist an updated review since the first synthesis up to current development.

Keywords

Author Information

Dane Tadeu Cestarolli

• Department of Chemistry, Biotechnology and Bioprocess Engineering, Federal University of São João Del Rei, Campus Alto Paraopeba, Ouro Branco, MG, Brazil

Elidia Maria Guerra *

• Department of Chemistry, Biotechnology and Bioprocess Engineering, Federal University of São João Del Rei, Campus Alto Paraopeba, Ouro Branco, MG, Brazil

*Address all correspondence to: [email protected]

1. Introduction (Historical and sources)

The discovery of vanadium was marked by uncertainty and confusion due to its chemical similarity with some elements. In 1801, the Spanish mineralogist, Andrés Manuel Del Rio, discovered an element with the atomic number 23, in Mexico, in a lead mineral. Due to the similarity of its colors to those of chrome, Del Rio called this element as panchrome. Later, after noting that the color of these salts turned red when heated, he renamed it as erythron. However, Del Rio withdrew his claim when, four years later, it was suggested by the French chemist, Hippolyte Victor Collett-Desotils, that the mineral was really an impure chromium, provoking the retraction of Andrés Manuel Del Rio [1]. In 1830, Swedish chemist Nils Gabriel Sefström rediscovered the element in an oxide that it was found while working at an iron mine and gave it the name by which it is known today. A year later, in 1831, Friedrich Woehler confirmed that this element was the same already discovered by Del Rio in 1801. In 1867, Henry Enfield Roscoe, an English chemist, isolated it almost purely by reducing the chloride with hydrogen [1]. The name vanadium refers to the goddess of beauty in Scandinavian mythology Vanadis, also known as Freya, due to the beautiful variation in the color of its compounds. Vanadium is the nineteenth most abundant element in the earth’s crust (136 ppm), and the fifth among transition metals. Despite being a metal considered abundant, it is not found in its elemental form, but it is present in approximately 65 different minerals, among which stand out vanadinite, PbCl₂.3Pb₃ (VO₄)₂, carnotite, K₂(UO₂)₂(VO₄)₂.3H₂O, roscoelite K(V₃AlMg)₂(SiAl)4O₁₀(OH)₂ and patronite, V₂S₃ [2]. Of the world’s vanadium resources, most are present in magma, located in the Bushveld volcanic complex in South Africa, which has the world’s largest reserves of iron/vanadium, followed by Russia, the United States and China. In 2019, about 90% of vanadium was obtained from magnetite and titanomagnetite ores. Regarding vanadium production, China led the largest global production of 2019 through slag. Asia China is the world’s largest producer of vanadium, with 59%, followed by Russia accounting for 17% and South Africa with 7% of the global supply of vanadium. Most of its vanadium was derived from the primary production of Bushveld Minerals and Glencore. The most commercially available vanadium products are vanadium pentoxide and iron-vanadium. Vanadium pentoxide is obtained by treating magnetite iron ores and slag.

2. Structures of vanadium oxides

The system of V-O has different oxidation states with V₂O₅ being the most stable. This system occurs from V 2+ to V 5+ such as vanadium monoxide (VO), vanadium sesquioxide (V₂O₃), vanadium dioxide (VO₂) and vanadium pentoxide (V₂O₅). Besides, it is possible to obtain mixed valence oxides that present several of oxides containing V 5+ /V 4+ mixture (in V₃O₇, V₄O₉, and V₆O₁₃) and V 4+ /V 3+ mixture (in V₆O₁₁, V₇O₁₃, and V₈O₁₅ [3]. From these mixing phases is possible to form two phases called as Magnéli phase (V_nO_2n-1) and Wadsley phase (V_nO_{2n + 1}). A schematic V-O phase diagram calculated by Kang [4] presented the Magnéli phase as being V₆O₁₃, V₃O₇, V₂O₅ as well as Wadsley phase V₃O₅, V₄O₇, V₅O₉, V₆O₁₁, V₇O₁₃ and V₈O₁₅. The phases and structures in the V-O phase diagram is depicted in Table 1.

Table 1.

Examples of phases and structures of V-O phase diagram.

From the Table 1, it is possible to observe that the V-O system can exhibits multiples crystalline structures. These crystalline structures can be modified considering the oxygen fractions in the range 0.5–0.75 and decrease of formation energy (eV.atom −1 ). It is worth mentioning that formation energy between the stable and metastable phases ranges, for example, between 4 meV in V₂O₅ and 35 meV in V₂O₃, making possible a reversible structural transition [5]. The Magnéli phase (V_nO_2n-1, with n = 4 to 9) is considered as being rutile-type with VO₆ octahedral [6]. The increase of n in V_nO_2n-1 compounds might has an inherent effect on the magnetic and electric properties.

On the other hand, Wadsley phase, (V_nO_{2n + 1}, with n = 1 to 6) is known as layered vanadium oxides. This V-O phase has single and double layers being able to accommodate V 4+ cations and both V 4+ /V 5+ cations, respectively [5, 7, 8]. The presence of these layers makes it possible to intercalate different ions which makes them suitable for energy conversion and storage [9]. Besides, mixed valence in Wadsley phase can be formed by introducing oxygen vacancy. The oxygen vacancy can generate mixed oxidation state with two oxidation states. It is possible to point out V₆O₁₃ with V 5+ /V 4+ as well as VO₂, V₂O₃, V₈O₁₅, V₇O₁₃, V₆O₁₁ with V 4+ /V 3+ species.

The most famous and stable of the layered V_nO_{2n + 1} is V₂O₅. Along the xyz axis (3D) V₂O₅ presents a V chains forming a network with oxygen which results as VO₅ pyramids [6]. X-ray diffraction (XRD) pattern of orthorhombic V₂O₅ and a layered crystalline structure has a standard pattern number JCPDS No. 41–1426 [10]. That way, its structure is orthorhombic with parameters a = 1.151 nm, b = 0.356 nm and c = 0.437 nm. From xy axis, V-O layer-like structure with two oxygen in z axis forming a distorted trigonal bipyramidal coordination polyhedral. Each combination of VO₅ pyramids has planes (00 l) and V is linked with five oxygen atoms by single bonds being four oxygen in xy axis and one oxygen in z axis. Then, in series of planes of VO₅ are connected with alternating oxygen position in z axis (perpendicular) according to the sequence two up and two down. Therefore, the V-O single bond in perpendicular position presents a weak interaction compared to oxygen located in adjacent layer [7, 11]. This layered characteristic makes enable an introduction of several ions into the lamellar spacing which bringing change of the crystalline structure resulting in different properties (Figure 1).

Figure 1.

Perspective view of two layers of V₂O₅. Weak van der Waals bonds are omitted for clarity.

V-O bonds from V₂O₅ have different distance caused by spontaneous deformation of the geometry to reduce the energy of the system. Then, vanadyl bond with four oxygen from the plane present a value of 0.178 nm. The bond of the extension along the z axis has 0.279 nm and the vertical axis opposite to the V–O bond has 0.158 nm.

Depending on the conditions, vanadium oxidation states might range of V 2+ to V 5+ as well as changes in coordination geometrics. Structural evolution in function of pH and concentration of V₂O₅ precursors are responsible by different oxidation states. Whenever a decrease of pH (13 to 1) and increase of H + /V (1 to 3 and concentration range from 10 −3 to 10 −1 mol.L −1 ) there are predominant species such as pyrovanadate, metavanadates, decavanadates, respectively. The main reaction that occurs during the formation of V₂O₅ are called olation and oxolation which will be detailed in Section 3.

It is possible to find V₂O₅ as α, β, and γ polymorphs (Figure 2) and among them have four orthorhombic, two monoclinic and one triclinic phase. α-V₂O₅ is a stable phase with an interlayer spacing of 0.452 nm. After a distortion forming by VO₆ in the V₂O₅ structure, V atoms are dislocated to the corner from the middle forming β-V₂O_5. γ-V₂O₅ presents oxygen alternated up and down pyramids connected with vanadium in the center and each VO₅ square pyramids forming zig-zag structure. There is a V=O bond along z axis that presents a weak bond and a covalent bond along x and y axis, creating double layers of O-V-O which is considered as short and strong. These torsion on structure makes γ-V₂O₅ more flexible and results in a structure metastable [12, 13].

Figure 2.

Structures polymorphs of V₂O₅.

The double layers of O-V-O are separated by van der Waals bond being a weak one. The different bonds along the coordinates of V₂O₅ creating a strong anisotropic in the V₂O₅ as 2-D layered material. Then, the basal plane (010) presents lower surface energy compared to (100) and (001) planes. As V₂O₅ presents plane as stacking of playing cards with weak interlayer force, it is possible to provides an intercalation reaction with several substances [12].

3. Structure of V₂O₅ based on its obtaining methods

In this section various conditions of synthesis and preparation methodology will be approached as well as their structural influences on V₂O₅. The interesting of V₂O₅ is focused on its versatility in several applications based on obtaining methods. The most used preparation technique is sol–gel but other methods such as hydrothermal/solvothermal synthesis, electrospinning, chemical vapor deposition (CVD), physical vapor deposition (PVD), template-based methods, reverse micelle techniques, Pechini method and electrochemical deposition can be used as well. Often, combinations of these methods can be found to obtain different structures of V₂O₅. The control of reaction conditions allows the formations of V₂O₅ as powder, nanomaterial, thin films, porous materials, among others.

Sol–gel – The sol–gel method (or synthesis or process) is basically based on hydrolysis and condensation of precursor material. This method was reported by Ditte in 1885 [14] that observed a formation of a red sol when the ammonium vanadate precursor was heated with nitric acid and water inside of platinum crucible. Other similar experiments were published some years later by Blitz [14]. During the sol–gel process the formation of V₂O₅ occurs during the olation and oxolation stages in pH 2 (Figure 3). Throughout the olation, the V 5+ central is hexacoordinate with water and, opposite side, oxygen with double bond in z axis. Other four bonds are orientated in the equatorial plane which x axis occur water and -OH bonds in opposite sides. Finally, in y axis there are two bonding of -OH in opposite sides. Due to distortion in the structure the length of bonds is not equal and the release of water molecule from x axis occurs resulting in the connection between V 5+ central link with oxygen from the other molecule coordinate forming the olation chain polymers. After the olation occurs a reaction in z axis called oxolation. The oxolation lead to the formation of edge sharing double chains in y axis. During this stage occurs a condensation resulting in polymerization of (-O-V-O′-)_n, which linked together whit O′ from other -O′-V- molecule coordinate. Finally, orderly planes along the y axis of polymerized VO_x are formed and connected by Van der Waals force. Other planes are generating a lamellar structure with interlayer distance around 1.17 nm [15]. Through this interlayer spacing, it is possible to perform an intercalation reaction of different substances without interfering in the crystallinity of V₂O₅ (topotactic process) [15, 16, 17, 18]. Intercalation reactions yield new materials with different or improved properties (synergic effect). V₂O₅ obtained from sol–gel synthesis has low viscosity, reddish brown color and after dry in room temperature is formed a xerogel of V₂O₅ thin film. The properties will be discussed in Section 4.

Figure 3.

Hydrothermal/solvothermal synthesis – Hydrothermal and solvothermal synthesis or method is widely used in inorganic synthesis. This method is often carried out in an autoclave with high-temperature aqueous solutions at high vapor pressures. Then, hydrothermal method can be defined as a method of synthesis of crystals or particles that depends on the solubility of inorganic material in hot solution under high pressure. V₂O₅ obtained from hydrothermal synthesis is a powder solid and generally use a salt of metavanadate. The V₂O₅ power presents an orthorhombic oxide α-V₂O₅ that exhibits a layered structure made of edge and corner sharing [VO₅] double chains [19]. However, there are several vanadium coordination as trigonal bipyramids to square pyramids and tetrahedra as well as a variety of crystalline V₂O₅. Additionally, varying conditions it is possible to obtain different nanostructure from hydrothermal synthesis as nanowires, nanobelts, nanorods, nanotubes, nano-urchin shapes, hollow nanospheres, nanosheets and nanoflowers. Porous material as micro, meso and macroporous can be obtained as well. The combination of hydrothermal synthesis with V₂O₅ obtained by sol–gel route can generate new materials with different structures and scale.

Electrospinning – electrospinning is a method that presents low cost, easy to control, simple and versatile. The method was patented by J.F. Cooley in February 1902 (U.S. Patent 692,631) and by W.J. Morton in July of the same year (U.S. Patent 0,705,691). This method consists of a syringe needle connected to a high voltage power supply (5 to 50 kV), a syringe pump and a collector. Voltage is applied and the sol–gel is ejected from needle tubing forming a nanowire. Thus, voltages, viscosity of the sol–gel, speed of syringe pump, and the humidity are the key factors which will affect the nanostructure of the nanowire. The solution is ejected from the needle tip with a constant rate by a syringe pump with constant feed pressure. Then, the high voltage applied transforms the liquid charged and the electrostatic repulsion counteracts the surface tension, and the droplet is stretched. Through the electrostatic repulsion, small bends in the fiber are deposited on the grounded collector. Due to the manner of deposition, the elongation and thinning of the fiber leads to the formation of uniform fibers with nanometer-scale diameters with novel physical properties [20]. With controlled deposition, the improve of properties is achieved and which leads to an enhancement of surface being the key to properties for superior chemical sensors.

C hemical vapor deposition (CVD) – chemical vapor deposition presents a film control composition via the control of chemical precursors producing a nanostructure V₂O₅ thin film. It is an interesting method because material is produced by the chemical reaction of vapor phase precursors in the gas phase and at the substrate surface. CVD presents advantage as precise control of film composition and it can coat large areas. There are variant of chemical vapor deposition (CVD) methods: thermally activated CVD (TACVD), plasma-enhanced CVD (PECDV), photo-initiated CVD (PICVD), pulsed-pressure metal organic CVD, atmospheric pressure CVD, atomic layer deposition, spray pyrolysis, plasma-enhanced CVD, aerosol-assisted CVD and so on [21, 22]. Basically, a vanadium precursor is dissolved in a solution and transported using ultrasonic. Then, the solution is put into a heated reactor with N₂ carrier gas. When the reaction is completed, about 1 h, the reactor is cooled to room temperature. The as-deposited coatings were brightly yellow in color and strongly adhered to the substrate [23]. The material obtained is transported to the substrate surface in the form of vapors, gases and volatilized liquid or in some cases a solid, would sublime directly and is generally prepared by injection of the liquid into solvent or heated evaporators [21, 22].

Template-based methods – this method for synthesis of nanostructured materials using templates is been widely used [24]. It consists of the use of molder with desired morphology as a template to guide the formation of products, which as, a result possess a similar morphology with the template after calcination. The template presents different shapes that can be controlled through adjusting parameters. Guerra et al . [25] investigate the effect of the mesoporosity exhibited by a mesostructured vanadium oxide obtained by sol–gel process and used as host cathode matrix on the Li + insertion/deinsertion process. Basically, all the proposed mechanisms are based on the same principle: the molecules of the surfactant (or structural directive) play a central role in molding or template for the formation of the mesoporous material. From the general point of view, the mechanism of formation of the mesoporous phase is based on electrostatic interactions between an inorganic precursor (I) and a surfactant (S) through a cooperative mechanism. The reaction involves a cationic surfactant and a negatively charged inorganic species, called S + I − synthesis. Similarly, this same group proposed syntheses using S − I + , S + X − I + (where X is a counterion) and S − M + I − (where M is a metallic cation). In the case of neutral S and I, it is believed that the process of self-organization takes place by hydrogen bonds. Through the use of templates, such as self-assembled organic surfactant, it is possible to obtain nanomaterials of different oxides [17, 24]. Nevertheless, this method presents disadvantage because the template used during the process needs to be removed by calcination, for example, at the end of synthesis increasing the cost and makes the preparation more complex.

Reverse micelle techniques (RM)– RM is used to prepare V₂O₅ nanostructured. To obtained nanomaterials are used nanometer-sized aggregates of surfactants with encapsulated water molecules inner the solvent. Different surfactants, including anionic, cationic, zwitterionic, nonionic and mixed surfactants can be used [26]. The nanometer-sized can be controlled by the water content expressed by (mol [water]/mol [surfactant]). Sulphosuccinic acid bis (2-ethylhexyl) ester sodium salt (AOT) is an anionic surfactant that is widely used to prepare RM to obtain V₂O₅ nanorods [27]. Pinna et al . [27] prepared V₂O₅ nanostructured from AOT with ([H2O]/[AOT]) being 10. From high-resolution images and structural characterization, it was possible to observe a lattice fringes of the nanocrystals with the γ-V₂O₅ structure for the nanorod oriented in the [101] direction and for the nanowire oriented in the [100] direction.

Electrochemical deposition – Electrochemical deposition or electrodeposition is frequently used to prepare nanomaterials or porous materials. This method has many advantages as low costs and flexibility compared to other methods. Besides, during the electrodeposition is possible to use room temperature and pressure. A nanomaterial can be synthetized using a small amount of templating agent to assemble and an electrochemical potential applied. The size of porous can be controlled by varying the electrodeposition conditions, such as deposition voltage, deposition time and surfactant concentration. After electrodeposition, the templating agent can be removed easily by washing with an appropriate solvent or calcination [28]. Generally, to prepare V₂O₅ by electrodeposition is used VOSO₄ as precursor in a mixture of deionized water and ethanol. A counter electrode and Ag/AgCl reference electrode are used during the electric voltage applied and the electrodeposition occurs onto an ITO/glass electrode. The pH can be adjusted according to the material to be obtained [29].

Pechini method – Pechini method is a kind of sol–gel method and is well-known wet chemical technique. During the synthesis is possible to use the same precursor of sol–gel method cited previously, but Pechini method involves the addition of alcohol and citric acid at room temperature resulting in a solid polymeric. The advantage of this method is ensuring compositional homogeneity of surface, low cost, homogeneous mixing at the molecular or atomic level, stoichiometric control, a lower calcining temperature, and a shorter heating time [30]. Then, from this method is possible to obtain V₂O₅ polycrystals with lattice parameters: a = 1.1514 nm, b = 0.3565 nm, c = 0.4374 nm, α = β = γ = 90° and lamellar morphology [31].

4. Properties and applications

V₂O₅ is a versatile material in terms of properties and importance in technological applications. This versatility is designed by rich morphologies and structures, various synthetic methods giving excellent properties. It is good to highlight that commercial V₂O₅ does not present electrochromic properties, for example, because of its low electrical conductivity, poor coloration efficiency and narrow color variation. Then, since the first synthesis of V₂O₅ several many studies have been proposed with the objective of obtaining this same oxide, however, with different syntheses. Thus, it was found that the change in preparation to obtain V₂O₅ had several important characteristics that result in structural change and, consequently, in the final properties and applications. Among them, it is observed that each type of synthesis causes variation in the band gap resulting in the variation of semiconductivity of V₂O₅. Generally, from the Tauc plot is possible to obtain the band gap value of V₂O₅. The value of the V₂O₅ band gap may shift, but always within the range of semiconductive materials. This result directly impacts in many final properties of this material. Then, with the innumerous possibilities of synthesis for obtaining V₂O₅ it became possible to make a structural and morphological manipulation resulting in a wide and varied potential in applications. Studies using V₂O₅ are mainly focused on characteristics and properties such as, electronic, magnetic, conductive, electrochemical, optical, mechanical, catalytic chemisoption among others.

More specifically, V₂O₅ can exhibits wide interesting and useful properties including metal–insulator transitions and electron. As addressed above, a layered structure like orthorhombic α-V₂O₅ can be a host for cation intercalation and potential application in Li-ion batteries. However, other metastable polymorph ζ-V₂O₅ is found to opens up the possibility of controlling the charge ordering of the network, and makes a prime candidate for applications in the next generation of Li- and multivalent-ion cathode materials [32]. The insertion/deinsertion of Li + occurs according to the reaction (1):

There are other phases that occurs as lithiated vanadium oxide LixV₂O₅ during the redox reaction. The amount of lithium, x, presents a variation according to the structure: α-V₂O₅ (x < 0.01), ε-LixV₂O₅ (0.35 < x < 0.7), δ-LixV₂O₅ (x = 1), γ-LixV₂O₅ (x < 2) and υ-LixV₂O₅ (x > 2) [7]. Structure manipulation to remodel V₂O₅ as nanosheet-assembled hollow microflowers by solvothermal method exhibits high specific capacity and remarkable cycling stability due to hierarchical structure with nanosheet subunits and hollow interior [10]. Regarding to electrodeposition of V₂O₅, this nanostructured material obtained can presents high energy density, power density, good cyclic stability over 200 cycles as high power and energy densities for thin film Li-ion batteries [33] and it has 5 times higher current density than sol–gel-derived film and can intercalate up to 5 times higher concentration of Li + [29]. Nanostructures can promote a rapid and facilitate the electron transfer ensuring satisfactory capacity retention even at high current densities, reduced ion diffusion distance and improved surface area. In theoretical terms, the specific capacity is much greater than those commercialized [8]. In general, using electrochemical studies to application as supercapacitor, V₂O₅ presents high capacitance and great energy density. A supercapacitor is an energy storage component, and comparing with battery, a supercapacitor presents more long lifetime, high power density, eco-friendly material and high efficiency [34]. It was found that V₂O₅ presents a range of 140 to 704.17 F.g −1 [34] using different synthesis and, consequently, different structures. It was found that the stability was 94.3% after 10,000 cycles indicating the potential of the V₂O₅ electrode for supercapacitor [35]. In general, V₂O₅ compound presents advantages in energy storage devices as ease to prepare even different method of synthesis, wide lithiation/delithiation potential and abundant storage.

V₂O₅ can be used as counter electrode (CE) in dye-sensitized solar cells (DSSC). Different methods to prepare V₂O₅ was demonstrated in literature [36, 37, 38]. The presence of V₂O₅ as component in DSSC contributed with power conversion efficiency in range of 2.04 to 3.80% using different method of obtaining as well as exhibited longer lifetime in an ambient environment, ease of film preparation at room temperature, low production cost and high optical transmittance over a wide range of solar spectrum [36, 37].

A gas sensor has a possibility to detect several gases in different atmospheres transforming the chemical reactions to analytically useful detectable signals. Then, the efficiency of a gas sensor depends on the materials present in sensor and the interaction of the gas with the material. The temperature can be an important factor between interaction of gas with materials on the surface of the sensor. Therefore, the choose of the material is particularly important. Consequently, V₂O₅ is found in several studies being a sensing material for several gas, such as, ammonia, ethanol, pH-sensor, EGFET pH-sensor, phenylhydrazine, NO₂, H₂O₂ and among others. In all cases, V₂O₅ demonstrated to be highly sensitivity in several temperature and under both dark and illumination conditions [18, 39, 40, 41, 42, 43, 44, 45, 46, 47]. Similar to the sensor, a biossensor turn an analytical response into a measurable chemical signal and detects only a certain biological product as a target analyte. The use of different structures of V₂O₅ as sensitive component in biosensor device has been explored in several target analyte such as urea, glucose, gene sequence, EGFET-biosensor, methylglyoxal in rice and among others [48, 49, 50, 51, 52, 53].

V₂O₅ presents optical property upon charging/discharging resulting in the color change. This ability to change its color by redox reaction is denominated electrochromic effect [54]. During the charge insertion into the vanadium is observed that the transmittance increases in the ultraviolet in a short wavelength of the spectrum, while the transmittance drops in the long-wavelength part of this spectrum near in infrared region. The optical and multicolor characteristics in V₂O₅ generate several applications such as in transmittance smart windows in energy efficient buildings, displays, in reflectance mirrors and emittance surfaces for temperature control of space vehicles. During the Li + extraction from V₂O₅ in range potential from −0.6 to +0.6 V the color of the film changes the deep blue to green and, finally, to yellow due to the oxidation of V 4+ to V 5+ . Initially, only partial V 4+ ions change to V 5+ at −0.3 V. In region more positive of potential, the remaining V 4+ ions turn to V 5+ . The reduction reaction occurs when the shift of potential to region more negative is applied makes the V₂O₅ a reversible capacity after several cycling [11, 55].

5. Conclusion

V₂O₅ has traditionally been used in various applications based on its obtained methods and properties of final structure. This chapter has summarized these obtaining methods using vanadium pentoxide with emphasis in different structure for wide applications. Since the first publication of V₂O₅ using sol–gel method, many reports have been found. The versatility and stability of V₂O₅ generated studies about structural changes according to the property of interest. Then, based on different obtaining techniques, it was possible to find structures of V₂O₅ such as nanostructures, lamellar, among others. Therefore, growth techniques have contributed to the extensive range of V₂O₅ applications. Additionally, depending on the conditions and methods, V₂O₅ films can have considerably different structural, optical, conductivity and electrical properties. The characteristic of V₂O₅ in offers a wide possibility of synthesis, low cost, easy to be obtained, revels that the material has high potential in several application areas being technological or innovation. Besides, in all application, the use of V₂O₅ has been demonstrated a promisor response and in a near future, the technology of designing new devices will have, as one of the components, the V₂O₅ presents on scale range.

Acknowledgments

The authors thank to INEO, FAPEMIG, RQ-MG/FAPEMIG, CNPq, UFSJ and CAPES.

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Мобільна розробка на Python менш популярна. Для Android частіше пишуть на Java, C #, C++ або Kotlin, а для iOS – на Swift або Objective-C. На Python зазвичай програмують серверну частину програми. Наприклад, клієнт Instagram для iOS написаний на Objective-C, а сервер – на Python.

Ігри

Багато комп’ютерних ігор були повністю або частково написані на Python. Існує хибна думка, що ця мова не підходить для серйозних проєктів, але насправді вона використовувався в розробці таких хітів, як:

Попри можливість реалізації призначеного для користувача інтерфейсу і роботи з графікою, на Python в основному пишуть скрипти – наприклад, взаємодії персонажів, запуску сцен, а також обробки подій.

Вбудовані системи (embedded systems)

На Python розробляють вбудовані системи для різних пристроїв. Наприклад, мова прижилася в Raspberry Pi (комп’ютер розміром з карту пам’яті).

Ще проєкти з вбудованою системою на Python:

Мова застосовується у вбудованих системах верстатів з ЧПУ, засобах автоматичного регулювання (температури, витрати рідини, тиску і так далі) і в телекомунікаційному обладнанні.

Створення скриптів

Python підходить для написання плагінів і скриптів до вже готових програмах. Наприклад, для реалізації ігрової логіки або створення додаткових модулів. Скрипти на цьому мови вбудовують і в програми на інших мовах, щоб автоматизувати будь-які завдання.

Системне адміністрування

Системним адміністраторам Python потрібен для автоматизації завдань. Він простий, потужний і підтримує спеціальні пакети, які підвищують його ефективність. І, найголовніше, він за замовчуванням встановлений на всі сервери з ОС Linux.

Завдяки лаконічності Python можна швидко прочитати код і знайти слабкі місця. Форматування в мові – частина синтаксису.

Наукові дослідження

В Python є кілька бібліотек, які стануть в пригоді для проведення досліджень і обчислень:

• SciPy – бібліотека з науковими інструментами;
• NumPy – розширення, яке додає підтримку матриць і багатовимірних масивів, а також математичні функції для роботи з ними;
• Matplotlib – бібліотека для роботи з 2D- і 3D-графікою.

Завдяки бібліотекам і простоті освоєння мови багато вчених вибирають Python – особливо він популярний у математиків і фізиків.

Data Science

Python – один з найбільш використовуваних в Data Science мов. На ньому пишуть алгоритми програм з машинним навчанням і аналітичні програми. За допомогою нього обслуговують сховища даних і хмарні сервіси.

Також він допомагає парсити дані з інтернету. Наприклад, в Google Python застосовують для індексації сайтів.