Acid etching method for improving specific surface area of titanium suboxide and doped titanium suboxide powder

Abstract

The acid etching method for increasing the specific surface area of ​​titanium suboxide and doped titanium suboxide powder described in this invention has two technical solutions. The first solution uses low specific surface area titanium suboxide powder or low specific surface area doped titanium suboxide powder and an aqueous solution of HCl and H2O as raw materials. 2 SO 4 Aqueous solution, HNO 3 The first method involves mixing at least one of the above-mentioned raw materials in an aqueous solution to form a liquid. This liquid is then poured into a reaction vessel and placed in a heating furnace. The temperature is raised to 130–150°C for a hydrothermal reaction. The reaction product is then washed successively with deionized water and anhydrous ethanol by centrifugation to remove acidic substances, followed by drying. The second method uses low specific surface area sub-titanium oxide powder or low specific surface area doped sub-titanium oxide powder and an aqueous HF solution or an HF-ethanol solution. The low specific surface area sub-titanium oxide powder or low specific surface area doped sub-titanium oxide powder is added to the aforementioned HF solution and stirred at room temperature for 15–24 hours to obtain a reaction product. The reaction product is then washed successively with deionized water and anhydrous ethanol by centrifugation to remove HF, followed by drying.

Description

Acid etching method to improve the specific surface area of ​​titanium suboxide and doped titanium suboxide powder Technical Field

[0001] This invention belongs to the technical field of improving the specific surface area of ​​powder materials, and particularly relates to a method for improving the specific surface area of ​​titanium suboxide powder and its doped powder. Background Technology

[0002] Titanium suboxide is based on rutile TiO2, and its ordered structure is formed by the spontaneous rearrangement of atoms through the creation of oxygen vacancies in TiO2. This unique crystal structure endows titanium suboxide with excellent electrical, electrochemical, and visible light response properties, making it a promising additive or carrier material for a wide range of industrial applications, including lithium batteries, fuel cells, lead-acid batteries, environmental protection (such as organic wastewater treatment), and electrometallurgy.

[0003] TiO2 suboxide powder and its doped powder are often prepared by high-temperature sintering, which involves reacting TiO2 powder or doped TiO2 powder with a reducing agent under high-temperature conditions. The main reducing agents include H2, NH3, CO, Ti, elemental carbon, or polymers that can provide a carbon source. However, a prominent problem with high-temperature sintering is the rapid growth of powder particles, resulting in a low specific surface area of ​​the material. Although using porous carbon hollow spheres, organic polymers, or other carbon-containing reducing agents to coat the surface of TiO2 powder can, to some extent, inhibit grain growth and increase the specific surface area of ​​the titanium suboxide powder, the process is complex, the templates are expensive, and the large amount of residual carbon results in impurities in the prepared titanium suboxide powder. For example, the method for preparing titanium suboxide powder disclosed by Wei et al. (see H. Wei at al, Chemical Bonding and Physical Trapping of Sulfur in Mesoporous Magnéli Ti4O7 Microspheres for High-Performance Li-S Battery[J], Advanced Energy) Materials (2017) reported that amorphous TiO2 microspheres were prepared in n-butanol via a sol-gel method using hexadecylamine as a template. The amorphous TiO2 microspheres (3.2 g) were then dispersed in a mixed solution of ethanol (40 mL), water (20 mL), and ammonia (2 mL). After stirring at room temperature for 30 min, the mixture was transferred to a hydrothermal synthesis reactor and heated at 160 °C for 16 h. The reaction product was then centrifuged, washed, and dried, and the resulting powder was calcined in air at 550 °C for 4 h to obtain mesoporous anatase TiO2 microspheres. These mesoporous TiO2 microspheres were then dispersed in a soluble phenolic resin solution and stirred at room temperature until all solvent evaporated. The sol and microsphere mixture was reacted at 100 °C for 24 h, and then calcined at 1000 °C for 6 h in argon. The specific surface area of ​​the obtained product reached 117 m². 2 / g, but it is a mixed powder of sub-titanium oxide phase and impurity carbon (impurity carbon content 25wt.%), and the process is extremely complex. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an acid etching method to improve the specific surface area of ​​titanium suboxide and doped titanium suboxide powder. This method can not only obtain titanium suboxide powder or doped titanium suboxide powder with high specific surface area and high purity, but also simplify the process.

[0005] The acid etching method for increasing the specific surface area of ​​titanium suboxide and doped titanium suboxide powder described in this invention has two technical solutions belonging to the same general inventive concept, due to the different etching acid solutions used.

[0006] 1. First technical solution

[0007] The raw materials are low specific surface area titanium suboxide powder or low specific surface area doped titanium suboxide powder and an acidic aqueous solution with a concentration of 0.5M to 1M. The process steps are as follows:

[0008] (1) The low specific surface area sub-titanium oxide powder or low specific surface area doped sub-titanium oxide powder is mixed with an acidic aqueous solution at a mass-to-volume ratio of 1:13 to 22. The unit of mass is g and the unit of volume is mL, or the unit of mass is kg and the unit of volume is L.

[0009] (2) Mix low specific surface area sub-titanium oxide powder or low specific surface area doped sub-titanium oxide powder with acidic aqueous solution to form a liquid. Then pour the liquid into a reaction vessel and place the reaction vessel containing the liquid into a heating furnace. Then heat the furnace to 130℃~150℃ and keep it at the temperature for 5h~24h to carry out hydrothermal reaction. After the holding time is reached, cool the furnace to room temperature to obtain the reaction product.

[0010] (3) The reaction product obtained in step (2) is first washed by centrifugation with deionized water, then washed by centrifugation with anhydrous ethanol to remove acidic substances, and then dried to obtain titanium suboxide powder with increased specific surface area or doped titanium suboxide powder with increased specific surface area.

[0011] The acidic aqueous solution is at least one of HCl aqueous solution, H2SO4 aqueous solution, and HNO3 aqueous solution.

[0012] In the above method, the heating rate of step (2) to 130℃~150℃ has no significant effect on the reaction product and is usually selected from the heating rate specified by the heating furnace used.

[0013] In the above methods, the solvent for HCl aqueous solution, H2SO4 aqueous solution, and HNO3 aqueous solution is deionized water.

[0014] 2. The second technical solution

[0015] The raw materials are low specific surface area titanium suboxide powder or low specific surface area doped titanium suboxide powder and HF aqueous solution or HF ethanol aqueous solution with a volume concentration of 0.13% to 4%. The process steps are as follows:

[0016] (1) The low specific surface area sub-titanium oxide powder or low specific surface area doped sub-titanium oxide powder is measured with HF aqueous solution or HF ethanol aqueous solution at a mass-to-volume ratio of 1:15-30. The unit of mass is g and the unit of volume is mL, or the unit of mass is kg and the unit of volume is L.

[0017] (2) Add low specific surface area sub-titanium oxide powder or low specific surface area doped sub-titanium oxide powder to HF aqueous solution or HF ethanol aqueous solution, and stir at room temperature for 15h to 24h to obtain the reaction product.

[0018] (3) The reaction product obtained in step (2) is first washed by centrifugation with deionized water, then washed by centrifugation with anhydrous ethanol to remove HF, and then dried to obtain sub-titanium oxide powder with increased specific surface area or doped sub-titanium oxide powder with increased specific surface area.

[0019] In the above method, the volume ratio of ethanol to deionized water in the HF ethanol aqueous solution is 75:1 to 3; the solvent of the HF aqueous solution is deionized water.

[0020] The titanium suboxide used in the method of this invention has the general formula Ti. n O 2n-1 , 3≤n≤10.

[0021] Compared with the prior art, the method described in this invention has the following beneficial technical effects:

[0022] 1. This invention provides a new technical solution for improving the specific surface area of ​​titanium suboxide and doped titanium suboxide powder. Using the method described in this invention, the specific surface area of ​​low specific surface area titanium suboxide powder or low specific surface area doped titanium suboxide powder can be significantly improved (see various embodiments).

[0023] 2. The method described in this invention can not only increase the specific surface area of ​​low specific surface area titanium suboxide powder or low specific surface area doped titanium suboxide powder, but also ensure that no impurity carbon is generated, thus obtaining pure phase titanium suboxide powder or doped titanium suboxide powder with a high specific surface area (see various embodiments).

[0024] 3. Since the method described in this invention uses low specific surface area titanium suboxide or doped titanium suboxide powder, HCl, H2SO4, HNO3, and hydrofluoric acid as raw materials, the requirements for raw materials are low, which is conducive to mass production.

[0025] 4. The method described in this invention is simple in process, easy to control, and uses conventional equipment, thus facilitating its promotion and application. Attached Figure Description

[0026] Figure 1 shows the detection results of the low specific surface area Ti4O7 powder used in Examples 1, 3 and 5 of this invention, where (a) is an XRD pattern, (b) is a SEM pattern and (c) is a nitrogen isothermal adsorption-desorption curve.

[0027] Figure 2 shows the low specific surface area Ti5O9 and Ti6O raw materials used in Example 2 of the present invention. 11 The images show the detection results of the mixed powder, where (a) is the XRD pattern, (b) is the SEM pattern, and (c) is the nitrogen isothermal adsorption-desorption curve.

[0028] Figure 3 shows the detection results of the low specific surface area V-doped Ti4O7 powder used in Example 6 of the present invention. (a) is an XRD pattern, (b) is a SEM pattern, (c) is a nitrogen isothermal adsorption-desorption curve, (d) is an EDS Ti elemental surface scan, and (e) is an EDS V elemental surface scan.

[0029] Figure 4 shows the detection results of low specific surface area Ce-doped Ti4O7 powder in Example 4 of the present invention, wherein (a) is an XRD pattern, (b) is a SEM pattern, (c) is a nitrogen isothermal adsorption-desorption curve, (d) is an EDS Ti elemental surface scan, and (e) is an EDS Ce elemental surface scan.

[0030] Figure 5 shows the detection results of the product obtained by acid etching of Ti4O7 powder with low specific surface area in Example 1 of the present invention. In the figure, (a) is the XRD pattern, (b) is the SEM pattern, and (c) is the nitrogen isothermal adsorption-desorption curve.

[0031] Figure 6 shows the application of low specific surface area Ti5O9 and Ti6O in Example 2 of the present invention. 11 The images show the detection results of the products obtained by acid etching of the mixed powder, where (a) is the XRD pattern, (b) is the SEM pattern, and (c) is the nitrogen isothermal adsorption-desorption curve.

[0032] Figure 7 shows the detection results of the product obtained by acid etching of Ti4O7 powder with low specific surface area in Example 3 of the present invention, wherein (a) is an XRD pattern, (b) is a SEM image, and (c) is a nitrogen isothermal adsorption-desorption curve.

[0033] Figure 8 shows the detection results of the product obtained by acid etching of Ce-doped Ti4O7 powder with low specific surface area in Example 4 of the present invention. (a) is an XRD pattern, (b) is a SEM pattern, and (c) is a nitrogen isothermal adsorption-desorption curve.

[0034] Figure 9 shows the detection results of the product obtained by acid etching of Ti4O7 powder with low specific surface area in Example 5 of the present invention. (a) is the XRD pattern, (b) is the SEM pattern, and (c) is the nitrogen isothermal adsorption-desorption curve.

[0035] Figure 10 shows the detection results of the product obtained by acid etching of V-doped Ti4O7 powder with low specific surface area in Example 6 of the present invention. In the figure, (a) is the XRD pattern, (b) is the SEM pattern, and (c) is the nitrogen isothermal adsorption-desorption curve. Detailed Implementation

[0036] The acid etching method for improving the specific surface area of ​​titanium suboxide and doped titanium suboxide powder according to the present invention will be further described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the following examples, the raw materials are low specific surface area Ti4O7 powder, Ti5O9 and Ti6O 11 The mixed powder, V-doped Ti4O7 powder, and Ce-doped Ti4O7 powder were prepared in-house using the following method:

[0038] 1. Preparation of low specific surface area Ti4O7 powder

[0039] The process steps are as follows:

[0040] (1) Take ≥5g of commercially available nano TiO2 powder (purity > 99.0%, average particle size about 40nm) and place it into the corundum boat;

[0041] (2) The corundum boat containing TiO2 powder from step (1) was placed in a tube furnace, and argon gas was introduced into the tube furnace at a flow rate of 100 mL / min. Under the atmosphere of flowing argon gas, the temperature was increased to 950°C at a heating rate of 10°C / min. Sintering was carried out at 950°C for 4 hours under the atmosphere of flowing hydrogen gas. After sintering, the furnace was cooled to room temperature to obtain a specific surface area of ​​2.14 m². 2 The detection results of / g micron-sized Ti4O7 powder are shown in Figure 1.

[0042] 2. Low specific surface area Ti5O9 and Ti6O 11 Preparation of mixed powders

[0043] The process steps are as follows:

[0044] (1) Take ≥5g of commercially available nano TiO2 powder (purity > 99.0%, average particle size about 40nm) and place it into the corundum boat;

[0045] (2) The corundum boat containing TiO2 powder from step (1) was placed in a tube furnace, and argon gas was introduced into the tube furnace at a flow rate of 100 mL / min. Under the atmosphere of flowing argon gas, the temperature was increased to 950°C at a heating rate of 10°C / min. Sintering was carried out for 3 hours at 950°C under the atmosphere of flowing hydrogen gas. After sintering, the furnace was cooled to room temperature to obtain a specific surface area of ​​3.22 m². 2 The detection results of the micron-sized Ti3O5 and Ti4O7 mixed powder (g) are shown in Figure 2.

[0046] 3. Preparation of low specific surface area V-doped Ti4O7 powder

[0047] The process steps are as follows:

[0048] (1) Add 0.9g of ammonium metavanadate to 25mL of ethylene glycol and heat in a water bath at 80℃ until the ammonium metavanadate is completely dissolved.

[0049] (2) Add 25 mL of anhydrous ethanol to the solution obtained in step (1) and stir for 5 min;

[0050] (3) Add 7 mL of isopropyl titanate to the solution obtained in step (2) and stir for 30 min;

[0051] (4) Transfer the mixture obtained in step (3) to the reactor, and place the reactor containing the mixture into the muffle furnace. Then raise the temperature to 180°C at a heating rate of 10°C / min and hold for 15 hours. After the holding is completed, cool the reactor to room temperature.

[0052] (5) The hydrothermal reaction product obtained in step (4) was washed by centrifugation with deionized water and anhydrous ethanol three times to remove impurities, and then dried in an oven at 60°C for 12 hours to obtain a white powder.

[0053] (6) Place the white powder obtained in step (5) into a corundum boat, place the corundum boat containing the white powder in a tube furnace, and then introduce argon gas into the tube furnace at a flow rate of 100 mL / min. Under the atmosphere of flowing argon gas, heat the temperature to 350°C at a heating rate of 10°C / min, and then cool it to room temperature with the furnace to obtain V-doped TiO2 powder.

[0054] (7) The corundum boat containing V-doped TiO2 powder from step (6) was placed back into the tube furnace. Argon gas was then introduced into the tube furnace at a flow rate of 100 mL / min. Under the atmosphere of flowing argon gas, the temperature was increased to 950°C at a heating rate of 10°C / min. Sintering was carried out for 4 hours at 950°C under the atmosphere of flowing hydrogen gas. After sintering, the furnace was cooled to room temperature to obtain a specific surface area of ​​4.80 m². 2 The detection results of micron-sized V-doped Ti4O7 powder (g) are shown in Figure 3.

[0055] 4. Preparation of low specific surface area Ce-doped Ti4O7 powder

[0056] The process steps are as follows:

[0057] (1) Add 16.90g of titanium sulfate and 1.50g of cerium sulfate to a mixed solution of 75mL of ethanol and 75mL of deionized water, respectively, and stir for 30min.

[0058] (2) Transfer the mixture obtained in step (1) to the reactor, place the reactor containing the mixture into the muffle furnace, and then raise the temperature to 200℃ at a heating rate of 10℃ / min and hold for 10h. After the holding time is up, cool it to room temperature with the furnace.

[0059] (3) The hydrothermal reaction product obtained in step (2) was washed by centrifugation with deionized water and anhydrous ethanol three times to remove impurities, and then dried in an oven at 60°C for 12 hours to obtain Ce-doped TiO2 white powder.

[0060] (4) Place the Ce-doped TiO2 powder obtained in step (3) into an alumina boat, place the alumina boat containing the Ce-doped TiO2 powder in a tube furnace, and then introduce argon gas into the tube furnace at a flow rate of 100 mL / min. Under the atmosphere of flowing argon gas, heat the furnace to 950°C at a heating rate of 10°C / min, and sinter at 950°C for 4 hours under the atmosphere of flowing hydrogen gas. After sintering, cool the furnace to room temperature to obtain a specific surface area of ​​4.11 m². 2 The detection results of micron-sized Ce-doped Ti4O7 powder (g) are shown in Figure 4.

[0061] In the following examples, HCl, H2SO4, HNO3, 40wt% hydrofluoric acid, and anhydrous ethanol were all purchased commercially and were of analytical grade; the muffle furnace used was model SXL-1700C.

[0062] Example 1

[0063] In this embodiment, the self-made specific surface area of ​​2.14m² is used. 2 Using micron-sized Ti4O7 powder (g) and a 0.5M HCl aqueous solution as raw materials, the process steps are as follows:

[0064] (1) Add 1g of raw material Ti4O7 powder to 13mL of HCl aqueous solution and stir at room temperature for 30min at 600RPM to make it evenly mixed to form a liquid.

[0065] (2) Pour the liquid obtained in step (1) into the reactor, and place the reactor containing the liquid into the muffle furnace. Then raise the temperature inside the furnace to 130°C at a heating rate of 10°C / min and keep it at that temperature for 24 hours. After the holding time is reached, cool the furnace to room temperature to obtain the reaction product.

[0066] (3) The reaction product obtained in step (2) is first washed three times by centrifugation with deionized water, and then washed three times by centrifugation with anhydrous ethanol to remove HCl. After drying in an oven at 60°C for 12 hours, the prepared powder is obtained.

[0067] The powder prepared in this embodiment was tested, and its XRD pattern is shown in Figure 5(a), SEM image is shown in Figure 5(b), and nitrogen isothermal adsorption-desorption curve is shown in Figure 5(c). Figure 5(a) shows that the powder prepared in this embodiment is a pure Ti4O7 phase. Figures 5(b) and 5(c) show that the Ti4O7 powder prepared in this embodiment has a specific surface area of ​​7.44 m². 2 The nanoscale layered structure has a specific surface area of ​​ / g, which is 2.14m² of the specific surface area of ​​the raw material Ti4O7 powder. 2 3.5 times that of (g).

[0068] Example 2

[0069] In this embodiment, the self-made specific surface area of ​​3.22m² is used. 2 / g of micron-sized Ti5O9 and Ti6O 11 Using mixed powder and a 1M H2SO4 aqueous solution as raw materials, the process steps are as follows:

[0070] (1) Add 1g of raw materials Ti5O9 and Ti6O 11 The mixed powder was added to 13 mL of H2SO4 aqueous solution and stirred at room temperature at 600 RPM for 30 min to mix it evenly and form a liquid.

[0071] (2) Pour the liquid obtained in step (1) into the reactor, and place the reactor containing the liquid into the muffle furnace. Then raise the temperature in the furnace to 150°C at a heating rate of 10°C / min and keep it at that temperature for 5 hours. After the holding time is reached, cool the furnace to room temperature to obtain the reaction product.

[0072] (3) The reaction product obtained in step (2) is first washed three times by centrifugation with deionized water, and then washed three times by centrifugation with anhydrous ethanol to remove H2SO4. After drying in an oven at 60°C for 12 hours, the prepared powder is obtained.

[0073] The powder prepared in this embodiment was tested, and its XRD pattern is shown in Figure 6(a), SEM image is shown in Figure 6(b), and nitrogen isothermal adsorption-desorption curve is shown in Figure 6(c). As can be seen from Figure 6(a), the powder prepared in this embodiment is Ti5O9 and Ti6O. 11 The mixture is free of other impurities; as can be seen from Figures 6(b) and 6(c), the Ti5O9 and Ti6O prepared in this embodiment are mixed phases without other impurities. 11 The mixed powder has a specific surface area of ​​10.27 m². 2 / g of nano-sized particle powder, whose specific surface area is greater than that of raw materials Ti5O9 and Ti6O 11 Specific surface area of ​​the mixed powder (3.22 m²) 2 3.2 times that of (g).

[0074] Example 3

[0075] In this embodiment, the self-made specific surface area of ​​2.14m² is used. 2 Using / g of micron-sized Ti4O7 powder and a 1M HNO3 aqueous solution as raw materials, the process steps are as follows:

[0076] (1) Add 0.6g of raw material Ti4O7 powder to 13mL of HNO3 aqueous solution and stir at room temperature for 30min at 600RPM to make it evenly mixed to form a liquid.

[0077] (2) Pour the liquid obtained in step (1) into the reactor, and place the reactor containing the liquid into the muffle furnace. Then raise the temperature in the furnace to 150°C at a heating rate of 10°C / min and keep it at that temperature for 6 hours. After the holding time is reached, cool the furnace to room temperature to obtain the reaction product.

[0078] (3) The reaction product obtained in step (2) is first washed three times by centrifugation with deionized water, and then washed three times by centrifugation with anhydrous ethanol to remove HNO3. After drying in an oven at 60°C for 12 hours, the prepared powder is obtained.

[0079] The powder prepared in this embodiment was tested, and its XRD pattern is shown in Figure 7(a), SEM image is shown in Figure 7(b), and nitrogen isothermal adsorption-desorption curve is shown in Figure 7(c). Figure 7(a) shows that the powder prepared in this embodiment is a pure Ti4O7 phase. Figures 7(b) and 7(c) show that the Ti4O7 powder prepared in this embodiment has a specific surface area of ​​12.05 m². 2 The nanostructure has a specific surface area of ​​ / g, which is 2.14m² of the raw material Ti4O7 powder. 2 It is 5.6 times that of g).

[0080] Example 4

[0081] In this embodiment, the self-made specific surface area is 4.11m². 2 The raw materials are micron-sized Ce-doped Ti4O7 powder ( / g) and 4% (v / v) HF aqueous solution. The 4% (v / v) HF aqueous solution is prepared with 40 wt% hydrofluoric acid and deionized water. The process steps are as follows:

[0082] (1) 1g of Ce-doped Ti4O7 powder was added to 30mL of HF aqueous solution and stirred at 600RPM for 15h at room temperature to obtain the reaction product;

[0083] (2) The reaction product obtained in step (1) is first washed three times by centrifugation with deionized water, and then washed three times by centrifugation with anhydrous ethanol to remove HF. After drying in an oven at 60°C for 12 hours, the prepared powder is obtained.

[0084] The powder prepared in this embodiment was tested, and its XRD pattern is shown in Figure 8(a), SEM image is shown in Figure 8(b), and nitrogen isothermal adsorption-desorption curve is shown in Figure 8(c). As can be seen from Figure 8(a), the powder prepared in this embodiment has Ti4O7 and Ti6O phases. 11 No Ce oxide phase was found; Ce has entered Ti4O7 and Ti6O. 11 The crystal structure of Ti4O7 and Ti6O 11 It is a Ce-doped solid solution; as can be seen from Figures 8(b) and 8(c), the powder prepared in this embodiment has a specific surface area of ​​11.49 m². 2 The nanoscale layered structure has a surface area of ​​ / g, which is 4.11m² higher than that of the raw material Ce-doped Ti4O7 powder. 2 It is 2.8 times that of g.

[0085] Example 5

[0086] In this embodiment, the self-made specific surface area of ​​2.14m² is used. 2 The raw materials are micron-sized Ti4O7 powder (g) and HF ethanol aqueous solution (0.13% by volume), wherein the volume ratio of ethanol to deionized water in the HF ethanol aqueous solution is 75:1. The process steps are as follows:

[0087] (1) Add 2g of raw material Ti4O7 powder to 30mL of HF ethanol aqueous solution and stir at 600RPM for 24h at room temperature to obtain the reaction product;

[0088] (2) The reaction product obtained in step (1) is first washed three times by centrifugation with deionized water, and then washed three times by centrifugation with anhydrous ethanol to remove HF. After drying in an oven at 60°C for 12 hours, the prepared powder is obtained.

[0089] The powder prepared in this embodiment was tested, and its XRD pattern is shown in Figure 9(a), SEM image is shown in Figure 9(b), and nitrogen isothermal adsorption-desorption curve is shown in Figure 9(c). Figure 9(a) shows that the powder prepared in this embodiment is a pure Ti4O7 phase. Figures 9(b) and 9(c) show that the powder prepared in this embodiment has a specific surface area of ​​5.02 m². 2 / g of micron-sized particles with a nanoporous structure has a specific surface area that is 2.14m² of the raw material Ti₄O₇ powder. 2 It is 2.3 times that of g).

[0090] Example 6

[0091] In this embodiment, the self-made specific surface area of ​​4.80m² is used. 2The raw materials are micron-sized V-doped Ti4O7 powder (g) and 4% (v / v) HF ethanol aqueous solution, wherein the volume ratio of ethanol to deionized water in the HF ethanol aqueous solution is 75:3. The process steps are as follows:

[0092] (1) Add 1g of raw material V-doped Ti4O7 powder to 30mL of HF ethanol aqueous solution and stir at 600RPM for 24h at room temperature to obtain the reaction product;

[0093] (2) The reaction product obtained in step (1) is first washed three times by centrifugation with deionized water, and then washed three times by centrifugation with anhydrous ethanol to remove HF. After drying in an oven at 60°C for 12 hours, the prepared powder is obtained.

[0094] The powder prepared in this embodiment was tested, and its XRD pattern is shown in Figure 10(a), SEM image is shown in Figure 10(b), and nitrogen isothermal adsorption-desorption curve is shown in Figure 10(c). As can be seen from Figure 10(a), the powder prepared in this embodiment is a pure Ti4O7 phase, and no V oxide phase was found. V has entered the crystal structure of Ti4O7, making Ti4O7 a V-doped solid solution. As can be seen from Figures 10(b) and 10(c), the powder prepared in this embodiment has a specific surface area of ​​22.33 m². 2 The nanoscale layered structure has a specific surface area of ​​ / g, which is 4.80m² of the raw material V-doped Ti4O7 powder. 2 4.7 times that of (g).

Claims

1. An acid etching method for increasing the specific surface area of ​​titanium suboxide and doped titanium suboxide powder, characterized in that... The raw materials are low specific surface area pure phase titanium suboxide powder or low specific surface area doped titanium suboxide powder and acidic aqueous solution with a concentration of 0.5M~1M. The process steps are as follows: (1) The low specific surface area pure phase titanium suboxide powder or low specific surface area doped titanium suboxide powder and acidic aqueous solution are measured at a mass-to-volume ratio of 1:13~22, where the mass unit is g and the volume unit is mL, or the mass unit is kg and the volume unit is L; (2) The low specific surface area pure phase titanium suboxide powder or low specific surface area doped titanium suboxide powder and acidic aqueous solution are mixed evenly to form a material solution, and then the material solution is poured into The reaction product is placed in a reactor and the reactor containing the liquid is placed in a heating furnace. The temperature is then raised to 130℃~150℃ and kept at that temperature for 5h~24h for hydrothermal reaction. After the holding time is reached, the reaction product is cooled to room temperature with the furnace to obtain the reaction product. (3) The reaction product obtained in step (2) is first washed by centrifugation with deionized water, then washed by centrifugation with anhydrous ethanol to remove acidic substances, and then dried to obtain pure phase sub-titanium oxide powder with increased specific surface area or doped sub-titanium oxide powder with increased specific surface area. The acidic aqueous solution is at least one of HCl aqueous solution, H2SO4 aqueous solution, and HNO3 aqueous solution.

2. An acid etching method for improving the specific surface area of ​​titanium suboxide and doped titanium suboxide powder, characterized in that... The raw materials are low specific surface area pure phase titanium suboxide powder or low specific surface area doped titanium suboxide powder and HF aqueous solution or HF ethanol aqueous solution with a volume concentration of 0.13% to 4%. The dopants in the doped titanium suboxide powder include V or Ce. The process steps are as follows: (1) The low specific surface area pure phase titanium suboxide powder or low specific surface area doped titanium suboxide powder is weighed with HF aqueous solution or HF ethanol aqueous solution at a mass-volume ratio of 1:15 to 30. The mass unit is g and the volume unit is mL, or the mass unit is kg and the volume unit is L; (2) The low specific surface area pure phase titanium suboxide powder or low specific surface area doped titanium suboxide powder is added to HF aqueous solution or HF ethanol aqueous solution and stirred at room temperature for 15h to 24h to obtain the reaction product; (3) The reaction product obtained in step (2) is first washed by centrifugation with deionized water, then washed by centrifugation with anhydrous ethanol to remove HF, and then dried to obtain pure phase titanium suboxide powder or doped titanium suboxide powder with increased specific surface area.

3. The acid etching method for increasing the specific surface area of ​​titanium suboxide and doped titanium suboxide powder according to claim 2, characterized in that... In HF ethanol aqueous solution, the volume ratio of ethanol to deionized water is 75:1~3.

Images