Monodisperse indium-doped tungsten oxide nano material with adjustable morphology and size and preparation method thereof

Abstract

The invention discloses a monodisperse indium-doped tungsten oxide nano material with adjustable morphology and size and a preparation method, and belongs to the technical field of nano materials, and the specific preparation method comprises the following steps: preparing a tungsten-containing precursor solution; adding indium salt to be doped into the tungsten precursor solution, and uniformly mixing; heating the mixed precursor solution under the protection of inert atmosphere to carry out solvothermal reaction, cooling to room temperature, and carrying out centrifugal purification to obtain monodisperse indium-doped tungsten oxide (WO3-x, 0lt; xlt; and 3) a nano material. In < 3 + > doping is introduced into the tungsten oxide nanocrystal through simple operation, the morphology and size of the nanomaterial can be regulated and controlled, and more choices are provided for photocatalysis, sensing, energy storage and electrochromic materials.

Description

Technical Field

[0001] The present invention relates to the field of nanomaterials, and particularly to a monodisperse indium-doped tungsten oxide (WO 3-x , 0 < x < 3) nanomaterial with adjustable morphology and size and a preparation method thereof. Background Art

[0002] With the development of nanotechnology, low-dimensional nanomaterials have been widely used in fields such as catalysis, optoelectronics, sensing, and energy storage due to their unique physical and chemical properties. Tungsten oxide (WO3), as an important functional semiconductor material, has received extensive attention due to its excellent electrochromic, photocatalytic, gas-sensing, and electrochemical properties. In particular, non-stoichiometric tungsten oxide (WO 3-x , 0 < x < 3) materials have high catalytic activity, good electronic conductivity, and unique optical properties due to their abundant oxygen vacancies, and thus have broad potential in applications such as photocatalysis, gas sensing, and electrochromic electrodes.

[0003] Doping is one of the important ways to regulate the properties of tungsten oxide. In particular, the doping of transition metals and rare earth elements can effectively improve the optoelectronic properties and catalytic activity of WO 3-x . Chinese invention patent CN 110681395 A discloses a Cu + -doped W 18 O 49 composite material and a preparation method thereof. However, the morphology and size of the nanomaterials prepared by this method are limited in adjustment, only changing from nanowires with a diameter of 500 - 1000 nm to nanorods with a diameter of 50 - 500 nm. The prepared tungsten oxide nanomaterials have a wide size distribution and serious agglomeration, which affects their optoelectronic properties.

[0004] The solvothermal method using oleylamine and octadecene as ligands is an important method for synthesizing high-quality nanomaterials, especially metal nanoparticles, semiconductor quantum dots, etc. Its advantage lies in that by adjusting the solvent ratio, reaction temperature, and time, the size, morphology, and surface functionalization of nanomaterials can be precisely controlled. This method not only improves the stability and dispersibility of nanomaterials, but also has broad application prospects in fields such as photocatalysis, supercapacitors, and electrochromics. In the existing literature (Yuan G, Hua C, Khan S, et al. Improved electrochromic performance of WO3 films with size - controlled nanorods[J]. Electrochim Acta, 2018, 260: 274 - 280.), monodisperse WO 3-xNanorods, by adjusting the ratio of surfactant octadecene to solvent oleylamine, achieved a size change of monodisperse nanorods from 38×3.2 nm to 89×4.5 nm. When applied to electrochromic films, the results showed that the response time of tungsten oxide electrochromic films strongly depends on the size of the nanorods. By precisely controlling the size of the nanorods, the electrochromic response time of the nanorods can be shortened by about 5 times. Although this method achieved the monodispersity of WO 3-x nanomaterials, it is limited in the regulation of morphology and size, and cannot achieve the regulation of smaller sizes and other dimensional nano-morphologies.

[0005] Recent studies have shown that the catalytic performance, optoelectronic performance, and stability of WO 3-x nanomaterials are all closely related to their morphology (such as particles, nanosheets, nanowires, nanospheres, etc.) and size (such as surface effects and quantum size effects at the nanoscale). In particular, by reasonable control of morphology and size, the specific surface area of the material can be increased, the number of reactive sites can be increased, and the electrochemical performance can be improved. Therefore, a preparation method of monodisperse WO 3-x nanomaterials with adjustable morphology and size has great research value and application potential. Summary of the Invention

[0006] In view of the above technical problems and the existing deficiencies in the art, the present invention aims to provide a monodisperse indium-doped tungsten oxide (WO 3-x , 0 < x < 3) nanomaterial with adjustable morphology and size and its preparation method.

[0007] To solve the above existing technical problems, the method of the present invention is realized through the following technical solutions: As a first aspect, the present invention provides a monodisperse indium-doped tungsten oxide nanomaterial with adjustable morphology and size. The nanomaterial is prepared by introducing In 3-x doping into tungsten oxide (WO 3+ , 0 < x < 3) nanocrystals; wherein In accounts for 0.5 to 30% of the molar amount of W in terms of molar percentage; when In accounts for 0.5 to 10% of the molar amount of W, the morphology of the nanomaterial is nanorods with a diameter of 1 to 5 nm and a length of 10 to 50 nm; when In accounts for 10 to 20% of the molar amount of W, the morphology of the nanomaterial is nanorods and nanosheets, and the number of nanosheets increases with the increase of the In 3+ doping amount, and the size is 50 to 100 nm; when In accounts for 20 to 30% of the molar amount of W, the morphology of the nanomaterial is nanosheets with a diameter of 100 to 500 nm.

[0008] As a second aspect, the present invention provides a preparation method of a monodisperse indium-doped tungsten oxide nanomaterial with adjustable morphology and size, including the following steps:

[0009] (1) adding a tungsten source and an oxidant to a solvent in sequence, mixing them evenly, and preparing a tungsten precursor solution;

[0010] (2) adding the indium salt to be doped into the tungsten precursor solution so that the molar percentage of In accounts for 0.5 to 30% of the molar amount of W, and mixing them evenly to obtain a mixed precursor solution;

[0011] (3) The mixed precursor solution is heated under the protection of an inert atmosphere to produce a solvothermal reaction, and after cooling to room temperature, centrifugal purification is performed to obtain monodisperse indium-doped tungsten oxide nanomaterials of different morphologies and sizes.

[0012] Furthermore, the tungsten source in step (1) is a mixture of one or more of hexacarbonyl tungsten, hexachloride tungsten and ammonium metatungstate in any proportion, the oxidant is trimethylamine oxide dihydrate, the solvent is oleylamine, the molar ratio of the oxidant to the tungsten source is 0 to 15 in molar percentage, and the molar volume ratio of the tungsten source to oleylamine is 0.05 to 0.2 mol / L.

[0013] Furthermore, in step (2), the indium salt is a mixture of one or more of indium chloride, indium sulfate, indium nitrate, indium acetate, and indium acetylacetonate in any proportion.

[0014] Furthermore, the solvent thermal reaction conditions in step (3) are: under the protection of an inert gas with a flow rate of 5 to 20 sccm of nitrogen or argon, the reaction temperature is 240 to 300° C., and the reaction time is 2 to 24 h.

[0015] Furthermore, the centrifugal purification in step (3) is specifically as follows: the cooled solution is dissolved with a non-polar solvent, and then a polar solvent is added for precipitation, wherein the volume ratio of the cooled solution, the non-polar solvent and the polar solvent is 1:(1-5):(2-10), and the solution is centrifuged at 6000-12000 rpm, and the dissolution, precipitation and purification process are repeated 3-6 times, and finally the prepared indium-doped tungsten oxide nanomaterial is dispersed in a non-polar solvent and stored for later use.

[0016] Furthermore, the polar solvent in step (3) is one or more of the following substances mixed in any proportion: methanol, ethanol, propanol, isopropanol; the non-polar solvent is one or more of the following substances mixed in any proportion: toluene, tetrachloroethylene, chloroform, n-hexane, cyclohexane, isooctane.

[0017] As a third aspect, the present invention provides a monodisperse indium-doped tungsten oxide nanomaterial with adjustable morphology and size, which is prepared by the preparation method described above.

[0018] As a fourth aspect, the present invention provides the application of the monodisperse indium-doped tungsten oxide nanomaterial with adjustable morphology and size in photocatalysis, sensing, energy storage, and electrochromism.

[0019] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0020] (1) The present invention uses In 3+ As a doping element, the morphology and size of tungsten oxide nanomaterials can be greatly controlled by changing the doping amount, providing more options for photocatalysis, sensing, energy storage and electrochromic materials.

[0021] (2) The present invention uses oleylamine as a surfactant to carry out a simple solvent thermal reaction, which can achieve monodispersity of tungsten oxide nanomaterials and provide a good basis for the preparation of high-quality doped tungsten oxide films. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work:

[0023] Figure 1 The digital photographs of the monodisperse indium-doped tungsten oxide nanomaterial toluene dispersion prepared by the present invention, wherein (a) is a digital photograph of the nanomaterial toluene dispersion of Comparative Example 1, (b) is a digital photograph of the nanomaterial toluene dispersion of Example 1, (c) is a digital photograph of the nanomaterial toluene dispersion of Example 2, (d) is a digital photograph of the nanomaterial toluene dispersion of Example 3, (e) is a digital photograph of the nanomaterial toluene dispersion of Example 4, and (f) is a digital photograph of the nanomaterial toluene dispersion of Example 5;

[0024] Figure 2 TEM and HRTEM images of the monodisperse tungsten oxide nanomaterial prepared in Comparative Example 1 of the present invention; wherein (a) is the TEM image of the nanomaterial, and (b) (c) are the HRTEM images of the nanomaterial;

[0025] Figure 3 TEM and HRTEM images of the monodisperse indium-doped tungsten oxide nanomaterial prepared in Example 1 of the present invention, wherein (a) is the TEM image of the nanomaterial, and (b) and (c) are HRTEM images of the nanomaterial;

[0026] Figure 4 TEM, HRTEM and electron diffraction pattern images of the monodisperse indium-doped tungsten oxide nanomaterial prepared in Example 2 of the present invention, wherein (a) is a TEM image of the nanomaterial, (b) is a HRTEM image of the nanomaterial, and (c) is an electron diffraction pattern image of the nanomaterial;

[0027] Figure 5TEM, HRTEM and electron diffraction pattern images of the monodisperse indium-doped tungsten oxide nanomaterial prepared in Example 3 of the present invention, wherein (a) is a TEM image of the nanomaterial, (b) is a HRTEM image of the nanomaterial, and (c) is an electron diffraction pattern image of the nanomaterial;

[0028] Figure 6 TEM, HRTEM and electron diffraction pattern images of the monodisperse indium-doped tungsten oxide nanomaterial prepared in Example 4 of the present invention, wherein (a) is a TEM image of the nanomaterial, (b) is a HRTEM image of the nanomaterial, and (c) is an electron diffraction pattern image of the nanomaterial;

[0029] Figure 7 TEM, HRTEM and electron diffraction pattern images of the monodisperse indium-doped tungsten oxide nanomaterial prepared in Example 5 of the present invention, wherein (a) is a TEM image of the nanomaterial, (b) is a HRTEM image of the nanomaterial, and (c) is an electron diffraction pattern image of the nanomaterial;

[0030] Figure 8 This is the EDS energy spectrum diagram of Example 5 of the present invention. DETAILED DESCRIPTION

[0031] The present invention uses a simple solvent thermal method to prepare monodisperse indium-doped tungsten oxide nanomaterials by controlling the appropriate ratio of precursor solutions and reaction time. In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The experimental methods in the following embodiments that do not specify specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0032] Comparative Example 1:

[0033] A monodisperse tungsten oxide nanomaterial and a preparation method thereof, comprising the following steps:

[0034] (1) In a 100 mL three-necked flask, add 15 mL of oleylamine, then add 0.525 g of hexacarbonyl tungsten and 1 g of trimethylamine oxide dihydrate, and stir at 60 °C for 30 min.

[0035] (2) After checking the tightness of the device, high-purity nitrogen was introduced for 30 minutes to remove the residual air in the flask. Then heating was started and the temperature was gradually raised to 270°C at a heating rate of 10°C / min. The reaction was kept warm for 24 hours, and the heating was turned off and cooled to room temperature. 15 mL of toluene was added to the mixture after the reaction was completed to dissolve it, and it was stirred for 2 minutes. Then 50 mL of ethanol antisolvent was added and centrifuged at 10000 rpm for 10 minutes to wash out the product. The dissolution and precipitation process was repeated 4 times. Finally, the obtained WO3-x The nanomaterials were dispersed in 10 mL of toluene to obtain monodispersed WO 3-x Nanomaterials.

[0036] Embodiment 1:

[0037] A monodisperse indium-doped tungsten oxide nanomaterial and a preparation method thereof, comprising the following steps:

[0038] (1) In a 100 mL three-necked flask, add 15 mL of oleylamine, then add 0.525 g of tungsten hexacarbonyl and 1 g of trimethylamine oxide dihydrate, and stir at 60 °C for 15 min.

[0039] (2) Add 0.022 g of indium acetate to the tungsten precursor solution in step (1) and stir at 60° C. for 15 min.

[0040] (3) After checking the tightness of the device, high-purity nitrogen was introduced for 30 minutes to remove the residual air in the flask. Then heating was started and the temperature was gradually raised to 270°C at a heating rate of 10°C / min. The reaction was kept warm for 24 hours, and the heating was turned off and cooled to room temperature. 15 mL of toluene was added to the mixture after the reaction was completed to dissolve it, and it was stirred for 2 minutes. Then 50 mL of ethanol antisolvent was added and centrifuged at 10000 rpm for 10 minutes to wash out the product. The dissolution and precipitation centrifugation process was repeated 4 times. Finally, the obtained WO 3-x The nanomaterials were dispersed in 10 mL of toluene to obtain monodisperse indium-doped WO 3-x The nanomaterial comprises In, which accounts for 5% of the molar amount of W by mole percentage.

[0041] Embodiment 2:

[0042] A monodisperse indium-doped tungsten oxide nanomaterial and a preparation method thereof, comprising the following steps:

[0043] (1) In a 100 mL three-necked flask, add 15 mL of oleylamine, then add 0.525 g of tungsten hexacarbonyl and 1 g of trimethylamine oxide dihydrate, and stir at 60 °C for 15 min.

[0044] (2) Add 0.044 g of indium acetate to the tungsten precursor solution in step (1) and stir at 60° C. for 15 min.

[0045] (3) After checking the tightness of the device, high-purity nitrogen was introduced for 30 minutes to remove the residual air in the flask. Then heating was started and the temperature was gradually raised to 270°C at a heating rate of 10°C / min. The reaction was kept warm for 24 hours, and the heating was turned off and cooled to room temperature. 15 mL of toluene was added to the mixture after the reaction was completed to dissolve it, and it was stirred for 2 minutes. Then 50 mL of ethanol antisolvent was added and centrifuged at 10000 rpm for 10 minutes to wash out the product. The dissolution and precipitation centrifugation process was repeated 4 times. Finally, the obtained WO3-x The nanomaterials were dispersed in 10 mL of toluene to obtain monodisperse indium-doped WO 3-x The nanomaterial comprises In, which accounts for 10% of the molar amount of W by mole percentage.

[0046] Embodiment 3:

[0047] A monodisperse indium-doped tungsten oxide nanomaterial and a preparation method thereof, comprising the following steps:

[0048] (1) In a 100 mL three-necked flask, add 15 mL of oleylamine, then add 0.525 g of tungsten hexacarbonyl and 1 g of trimethylamine oxide dihydrate, and stir at 60 °C for 15 min.

[0049] (2) Add 0.066 g of indium acetate to the tungsten precursor solution in step (1) and stir at 60° C. for 15 min.

[0050] (3) After checking the tightness of the device, high-purity nitrogen was introduced for 30 minutes to remove the residual air in the flask. Then heating was started and the temperature was gradually raised to 270°C at a heating rate of 10°C / min. The reaction was kept warm for 24 hours, and the heating was turned off and cooled to room temperature. 15 mL of toluene was added to the mixture after the reaction was completed to dissolve it, and it was stirred for 2 minutes. Then 50 mL of ethanol antisolvent was added and centrifuged at 10000 rpm for 10 minutes to wash out the product. The dissolution and precipitation centrifugation process was repeated 4 times. Finally, the obtained WO 3-x The nanomaterials were dispersed in 10 mL of toluene to obtain monodisperse indium-doped WO 3-x The nanomaterial comprises In, which accounts for 15% of the molar amount of W by mole percentage.

[0051] Embodiment 4:

[0052] A monodisperse indium-doped tungsten oxide nanomaterial and a preparation method thereof, comprising the following steps:

[0053] (1) In a 100 mL three-necked flask, add 15 mL of oleylamine, then add 0.525 g of tungsten hexacarbonyl and 1 g of trimethylamine oxide dihydrate, and stir at 60 °C for 15 min.

[0054] (2) Add 0.088 g of indium acetate to the tungsten precursor solution in step (1) and stir at 60° C. for 15 min.

[0055] (3) After checking the tightness of the device, high-purity nitrogen was introduced for 30 minutes to remove the residual air in the flask. Then heating was started and the temperature was gradually raised to 270°C at a heating rate of 10°C / min. The reaction was kept warm for 24 hours, and the heating was turned off and cooled to room temperature. 15 mL of toluene was added to the mixture after the reaction was completed to dissolve it, and it was stirred for 2 minutes. Then 50 mL of ethanol antisolvent was added and centrifuged at 10000 rpm for 10 minutes to wash out the product. The dissolution and precipitation centrifugation process was repeated 4 times. Finally, the obtained WO 3-x The nanomaterials were dispersed in 10 mL of toluene to obtain monodisperse indium-doped WO 3-x The nanomaterial comprises In, which accounts for 20% of the molar amount of W by mole percentage.

[0056] Embodiment 5:

[0057] A monodisperse indium-doped tungsten oxide nanomaterial and a preparation method thereof, comprising the following steps:

[0058] (1) In a 100 mL three-necked flask, add 15 mL of oleylamine, then add 0.525 g of tungsten hexacarbonyl and 1 g of trimethylamine oxide dihydrate, and stir at 60 °C for 15 min.

[0059] (2) Add 0.132 g of indium acetate to the tungsten precursor solution in step (1) and stir at 60°C for 15 min.

[0060] (3) After checking the tightness of the device, high-purity nitrogen was introduced for 30 minutes to remove the residual air in the flask. Then heating was started and the temperature was gradually raised to 270°C at a heating rate of 10°C / min. The reaction was kept warm for 24 hours, and the heating was turned off and cooled to room temperature. 15 mL of toluene was added to the mixture after the reaction was completed to dissolve it, and it was stirred for 2 minutes. Then 50 mL of ethanol antisolvent was added and centrifuged at 10000 rpm for 10 minutes to wash out the product. The dissolution and precipitation centrifugation process was repeated 4 times. Finally, the obtained WO 3-x The nanomaterials were dispersed in 10 mL of toluene to obtain monodisperse indium-doped WO 3-x The nanomaterial comprises In, which accounts for 30% of the molar amount of W by mole percentage.

[0061] Sample Analysis:

[0062] Figure 1 The digital photos are of the monodisperse indium-doped tungsten oxide nanomaterial toluene dispersions prepared in Comparative Example 1, Example 1, Example 2, Example 3, Example 4 and Example 5 of the present invention. It can be seen from the figure that the prepared indium-doped tungsten oxide nanomaterial is well dispersed in non-polar solvents such as toluene.

[0063] Figure 2The TEM and HRTEM images of the monodisperse tungsten oxide nanomaterial prepared in Comparative Example 1 of the present invention are shown in Figure 1. As can be seen from the figure, the undoped nano-tungsten oxide is rod-shaped, and the average size obtained after statistics is 42×1.9nm. In addition, it can be seen from the high-resolution imaging that the sample is a monoclinic phase of W 18 O 49 Nanorods have an oriented growth trend along the

[010] direction.

[0064] Figure 3 The TEM and HRTEM images of the monodisperse indium-doped tungsten oxide nanomaterial prepared in Example 1 of the present invention are shown in Figure 1. As can be seen from the figure, the morphology of the nano-tungsten oxide doped with 5at% In is still rod-shaped, but the size has changed significantly. Compared with the undoped sample, its aspect ratio is significantly reduced. The average size obtained after statistics is 18.6×2.8nm. It can be seen from the high-resolution imaging that the sample with a small amount of doping still grows along the

[010] direction, but the (010) crystal plane spacing increases, proving that In 3+ effective doping.

[0065] Figure 4 The TEM and HRTEM images of the monodisperse indium-doped tungsten oxide nanomaterial prepared in Example 2 of the present invention are shown in Figure 2. As can be seen from the figure, the morphology of the nano-tungsten oxide doped with 10 at% In is still rod-shaped, but its aspect ratio is further reduced compared to the undoped sample. The average size obtained after statistics is 11.1×3.4nm. It can be seen from the high-resolution imaging that the sample with a small amount of doping still grows along the

[010] direction, but due to the In 3+ Doping leads to a further increase in the (010) interplanar spacing.

[0066] Figure 5 TEM, HRTEM and electron diffraction patterns of monodisperse indium-doped tungsten oxide nanomaterials prepared in Example 3 of the present invention. It can be seen from the figure that In doped 15at% nano-WO 3-x The morphology changes, and flake products begin to appear, with an average size of 50.1×30.9nm. High-resolution and electron diffraction patterns show that the flake samples are hexagonal phases, indicating that the appropriate amount of In 3+ The doping will change the arrangement of [WO6] octahedron, from the original slightly doped monoclinic phase to the hexagonal tungsten bronze phase.

[0067] Figure 6TEM, HRTEM and electron diffraction pattern diagram of the monodisperse indium-doped tungsten oxide nanomaterial prepared in Example 4 of the present invention. It can be seen from the figure that the size and morphology of the nano-tungsten oxide material doped with 20at% In continues to change, the size of the nanosheet is 50-100nm, and the geometric morphology gradually becomes regular, and even nanosheets with regular hexagonal end faces can be observed. Through high resolution and electron diffraction patterns, it can be seen that the sheet product is a single crystal of hexagonal tungsten bronze phase.

[0068] Figure 7 TEM, HRTEM and electron diffraction patterns of monodisperse indium-doped tungsten oxide nanomaterials prepared in Example 5 of the present invention. As can be seen from the figure, when the doping amount of In is further increased to 30at%, the In-doped nano-tungsten oxide obtained is a nanosheet or nanodisk with a size of more than 100nm, and the end face geometry tends to be circular. It can be seen from the high resolution and electron diffraction patterns that the sheet product is a large-sized single crystal of hexagonal tungsten bronze phase.

[0069] Figure 8 This is the EDS spectrum of Example 5 of the present invention. It can be seen that In 3+ It is evenly distributed throughout the tungsten oxide nanosheets, and the In / W in Example 5 is calculated to be 27.9 at%, which is close to the theoretical value of 30%.

[0070] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A monodisperse indium-doped tungsten oxide nanomaterial with adjustable morphology and size, characterized in that: The nanomaterial introduces In into tungsten oxide nanocrystals. 3+ The nanomaterial is prepared by doping; wherein In accounts for 0.5 to 30% of the molar amount of W by mole percentage; when In accounts for 0.5 to 10% of the molar amount of W, the nanomaterial morphology is a nanorod with a diameter of 1 to 5 nm and a length of 10 to 50 nm; when In accounts for 10 to 20% of the molar amount of W, the nanomaterial morphology is a nanorod and a nanosheet, and the number of nanosheets increases with In. 3+ The size increases with the increase of the doping amount, and the size is 50-100nm; when In accounts for 20-30% of the molar amount of W, the nanomaterial morphology is a nanosheet with a diameter of 100-500nm.

2. A method for preparing a monodisperse indium-doped tungsten oxide nanomaterial with adjustable morphology and size, characterized in that: The specific steps include: (1) adding a tungsten source and an oxidant to a solvent in sequence, mixing them evenly, and preparing a tungsten precursor solution; (2) adding the indium salt to be doped into the tungsten precursor solution so that the molar percentage of In accounts for 0.5 to 30% of the molar amount of W, and mixing them evenly to obtain a mixed precursor solution; (3) The mixed precursor solution is heated under the protection of an inert atmosphere to produce a solvothermal reaction, cooled to room temperature, and then centrifuged for purification to obtain monodisperse indium-doped tungsten oxide nanomaterials of different morphologies and sizes.

3. The preparation method according to claim 2, characterized in that: The tungsten source in step (1) is a mixture of one or more of tungsten hexacarbonyl, tungsten hexachloride, and ammonium metatungstate in any proportion, the oxidant is trimethylamine oxide dihydrate, and the solvent is oleylamine. The molar ratio of the oxidant to the tungsten source is 0 to 15 in molar percentage, and the molar volume ratio of the tungsten source to oleylamine is 0.05 to 0.2 mol / L.

4. The preparation method according to claim 2, characterized in that: In step (2), the indium salt is one or more of indium chloride, indium sulfate, indium nitrate, indium acetate, and indium acetylacetonate mixed in any proportion.

5. The preparation method according to claim 2, characterized in that: The solvent thermal reaction conditions in step (3) are: under the protection of an inert gas with a flow rate of 5 to 20 sccm of nitrogen or argon, the reaction temperature is 240 to 300° C., and the reaction time is 2 to 24 h.

6. The preparation method according to claim 2, characterized in that: The centrifugal purification in step (3) is specifically as follows: the cooled solution is dissolved in a non-polar solvent, and then a polar solvent is added for precipitation, wherein the volume ratio of the cooled solution, the non-polar solvent and the polar solvent is 1:(1-5):(2-10), and the solution is centrifuged at a speed of 6000-12000 rpm, and the dissolution, precipitation and purification process are repeated 3-6 times, and finally the prepared indium-doped tungsten oxide nanomaterial is dispersed in a non-polar solvent for storage.

7. The preparation method according to claim 6, characterized in that: The polar solvent is a mixture of one or more of the following substances in any proportion: methanol, ethanol, propanol, isopropanol; the non-polar solvent is a mixture of one or more of the following substances in any proportion: toluene, tetrachloroethylene, chloroform, n-hexane, cyclohexane, isooctane.

8. A monodisperse indium-doped tungsten oxide nanomaterial with adjustable morphology and size, characterized in that: The product is prepared by the preparation method described in any one of claims 1 to 7.

9. Application of the monodisperse indium-doped tungsten oxide nanomaterial with adjustable morphology and size as claimed in claim 8 in photocatalysis, sensing, energy storage and electrochromism.

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