A non-metallic element in-situ doped Ti4O7 electrode and a preparation method thereof

Abstract

The application provides a non-metallic element in-situ doped Ti4O7 electrode and a preparation method thereof, and belongs to the technical field of electrochemistry. The non-metallic element is used to dope Ti4O7, the non-metallic element has greater electronegativity than the metal element, the non-metallic element doping is more conducive to regulating the electronic structure of Ti4O7, and theoretically can make Ti4O7 generate more ·OH and have higher oxidation capacity; the application uses a sol-gel method, takes polyethylene glycol as a carbon source and tetraethyl titanate as a titanium source, prepares a sol from the titanium source, the carbon source and two complexing agents, repeatedly soaks a porous Ti base material in the sol, finally sinter and reduces, generates Ti4O7 in-situ on the surface of the porous Ti base material, and under an oxygen-free environment, the titanium source precursor is reduced to Ti4O7 by carbon, oxygen vacancies are generated, and the electrode oxidation performance can be improved.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and in particular to a non-metallic element in-situ doped Ti4O7 electrode and its preparation method. Background Technology

[0002] In recent years, perfluorinated compound (PFC) pollution has spread to various ecosystems worldwide, far exceeding expectations. Its presence has even been detected in remote polar regions, posing a significant threat to life on Earth. Therefore, finding effective methods for perfluorinated compound degradation is urgently needed. Research indicates that electrochemical oxidation can effectively remove perfluorinated compounds from complex pollutant water bodies and is one of the most promising methods for the complete mineralization of perfluorinated compounds in water. Electrochemical oxidation degrades perfluorinated compounds by generating hydroxyl radicals (·OH) on the anode surface, which either transfer electrons to organic pollutants or directly to the pollutants, achieving the goal of complete mineralization.

[0003] Ti n O 2n-1 Ti4O7 is a high-performance conductive ceramic material with broad application prospects and significant research value. It possesses unique physical, chemical, and electrochemical properties. The oxygen defects in its crystal structure, in addition to giving it inherent ceramic characteristics, also endow it with metal-like conductivity, overcoming the limitation imposed on its further application by poor conductivity. n O 2n-1 Ti4O7, with its superior electrical conductivity, possesses a range of advantages including high conductivity, high chemical stability, and a wide potential window. It not only generates hydroxyl radicals but also facilitates direct electron transfer from pollutants to its surface, combining the characteristics of both active and inactive electrodes, making it an ideal electrode material for wastewater treatment. As an anode, Ti4O7 can directly transfer electrons with pollutants and generate ·OH to oxidize and remove them. Furthermore, ·OH exhibits a weak adsorption state on the electrode surface, demonstrating high oxidizing power and utilization rate. However, its relatively weak ·OH generation capacity limits the application of Ti4O7 electrodes. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a non-metallic element in-situ doped Ti4O7 electrode and its preparation method. The non-metallic element in-situ doped Ti4O7 electrode provided by this invention has good ·OH production capability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a Ti4O7 electrode doped with non-metallic elements in situ, comprising the following steps:

[0007] Polyethylene glycol, tetraethyl titanate, acetylacetone and methyl methacrylate were mixed to obtain a sol precursor;

[0008] The pH value of the sol precursor is adjusted to 5-6, and the pH-adjusted sol precursor is mixed with a non-metallic source, ethanol, and an organic dispersant, and then aged to obtain an aged sol; the non-metallic source is one or more of nitrogen, boron, phosphorus, sulfur, and silicon sources.

[0009] The porous Ti substrate is immersed in the aged sol, removed and dried, and the immersion-drying process is repeated multiple times. The porous Ti substrate that has been immersed in the aged sol multiple times is sintered in an oxygen-free environment to obtain a non-metallic element in-situ doped Ti4O7 electrode.

[0010] Preferably, the mass ratio of polyethylene glycol to tetraethyl titanate is 18-30:6-10;

[0011] The mass ratio of tetraethyl titanate to acetylacetone is 6-10:0.5-1;

[0012] The molar ratio of tetrabutyl titanate to methyl methacrylate is 6-10:0.5-1.

[0013] Preferably, the nitrogen source is melamine and / or urea;

[0014] The boron source is sodium tetraborate and / or magnesium borate;

[0015] The phosphorus source is sodium dihydrogen phosphate and / or potassium dihydrogen phosphate;

[0016] The sulfur source is sodium sulfate and / or zinc sulfate;

[0017] The silicon source is aluminum silicate and / or iron silicate.

[0018] Preferably, the mass of the non-metallic element in the non-metallic source is 1 to 5% of the mass of tetrabutyl titanate.

[0019] Preferably, the mass of the ethanol is 10-20% of the mass of the sol precursor.

[0020] Preferably, the organic dispersant is one or more of acetone, acetonitrile, methanol, and petroleum ether;

[0021] The mass of the organic dispersant is 20-30% of the mass of the sol precursor.

[0022] Preferably, the aging temperature is 60-80°C and the time is 12-24 hours.

[0023] Preferably, the time for a single immersion of the porous Ti substrate in the aging sol is 15 to 30 minutes; the immersion-drying process is repeated 3 to 7 times.

[0024] Preferably, the sintering temperature is 900–1100°C, and the holding time is 3–5 hours.

[0025] The present invention provides a non-metallic element in-situ doped Ti4O7 electrode prepared by the above preparation method, comprising a porous titanium substrate and Ti4O7 attached to the surface and interior of the porous titanium substrate; the Ti4O7 is doped with a non-metallic element, wherein the non-metallic element is one or more of nitrogen, boron, phosphorus, sulfur and silicon.

[0026] This invention provides a method for preparing a non-metallic element-doped Ti4O7 electrode, comprising the following steps: mixing polyethylene glycol, tetraethyl titanate, acetylacetone, and methyl methacrylate to obtain a sol precursor; adjusting the pH value of the sol precursor to 5-6; mixing the pH-adjusted sol precursor with a non-metallic source, ethanol, and an organic dispersant, and aging it to obtain an aged sol; wherein the non-metallic source is one or more of nitrogen, boron, phosphorus, sulfur, and silicon sources; immersing a porous Ti substrate in the aged sol, removing and drying it, repeating the immersion-drying process multiple times; and sintering the obtained porous Ti substrate repeatedly immersed in the aged sol under an oxygen-free environment to obtain a non-metallic element-doped Ti4O7 electrode. This invention utilizes non-metallic elements to dope Ti4O7. Non-metallic elements have greater electronegativity than metallic elements, and doping with non-metallic elements is more conducive to controlling the electronic structure of Ti4O7, theoretically enabling Ti4O7 to generate more ·OH groups and thus exhibit higher oxidation capacity. This invention employs a sol-gel method, using polyethylene glycol as a carbon source and tetraethyl titanate as a titanium source. The titanium source, carbon source, and two complexing agents are combined to form a sol. A porous Ti substrate is repeatedly immersed in the sol, followed by sintering and reduction. Ti4O7 is generated in situ on the surface of the porous Ti substrate. In an oxygen-free environment, the titanium source precursor is reduced to Ti4O7 by carbon, generating oxygen vacancies, which improves the electrode oxidation performance. Furthermore, this invention avoids the cumbersome process of preparing TiO2 powder first, followed by hydrogen reduction to prepare Ti4O7 powder, as required by existing technologies. It uses a single-step method to directly generate Ti4O7 in situ on the substrate surface, simplifying the operation and allowing for the generation of Ti4O7 material on substrates of any shape, which is beneficial for industrial application. The results of the examples show that, at a voltage of 5.4V, the yield of ·OH in the in-situ doped Ti4O7 electrode provided by the present invention is (4.08~4.25)×10⁻⁶. -8 mol / min / cm -2 It has a good ability to produce ·OH. Attached Figure Description

[0027] Figure 1 The curve showing the change in PFOA content over time is shown below. Figure 1 As shown. Detailed Implementation

[0028] This invention provides a method for preparing a Ti4O7 electrode doped with non-metallic elements in situ, comprising the following steps:

[0029] Polyethylene glycol, tetraethyl titanate, acetylacetone and methyl methacrylate were mixed to obtain a sol precursor;

[0030] The pH value of the sol precursor is adjusted to 5-6, and the pH-adjusted sol precursor is mixed with a non-metallic source, ethanol, and an organic dispersant, and then aged to obtain an aged sol; the non-metallic source is one or more of nitrogen, boron, phosphorus, sulfur, and silicon sources.

[0031] The porous Ti substrate is immersed in the aged sol, removed and dried, and the immersion-drying process is repeated multiple times. The porous Ti substrate that has been immersed in the aged sol multiple times is sintered in an oxygen-free environment to obtain a non-metallic element in-situ doped Ti4O7 electrode.

[0032] This invention involves mixing polyethylene glycol, tetraethyl titanate, acetylacetone, and methyl methacrylate to obtain a sol precursor. In this invention, the number-average molecular weight of the polyethylene glycol is preferably 200–1000, more preferably one or more of 200, 300, 400, 600, 800, and 1000.

[0033] In this invention, the preferred mass ratio of polyethylene glycol to tetraethyl titanate is 18–30:6–10, more preferably 20–25:7–9. This invention controls the amount of polyethylene glycol to be significantly greater than the amount of tetrabutyl titanate, ensuring that tetrabutyl titanate is reduced to Ti4O7 to the maximum extent.

[0034] In this invention, the mass ratio of tetraethyl titanate to acetylacetone is preferably 6–10:0.5–1, more preferably 7–9:0.5–1; the molar ratio of tetrabutyl titanate to methyl methacrylate is preferably 6–10:0.5–1, more preferably 7–9:0.5–1. In this invention, acetylacetone and methyl methacrylate act as complexing agents.

[0035] In this invention, the mixing is preferably carried out under a water bath at 60°C; the stirring rate is preferably 600-800 r / min, more preferably 700 r / min; and the stirring time is preferably 12-24 h, more preferably 16-20 h.

[0036] The pH value of the sol precursor is adjusted to 5-6, and the pH-adjusted sol precursor is mixed with a non-metallic source, ethanol, and an organic dispersant, and then aged to obtain an aged sol. In this invention, the reagent for adjusting the pH value is preferably nitric acid.

[0037] In this invention, the non-metallic source is one or more of nitrogen, boron, phosphorus, sulfur, and silicon sources; the nitrogen source is preferably melamine and / or urea; the boron source is preferably sodium tetraborate and / or magnesium borate; the phosphorus source is preferably sodium dihydrogen phosphate and / or potassium dihydrogen phosphate; the sulfur source is preferably sodium sulfate and / or zinc sulfate; and the silicon source is preferably aluminum silicate and / or iron silicate.

[0038] In this invention, the mass of the non-metallic element in the non-metallic source is preferably 1 to 5% of the mass of tetrabutyl titanate, more preferably 2 to 4%.

[0039] In this invention, the mass of ethanol is preferably 10-20% of the mass of the sol precursor, more preferably 15-18%. In this invention, to prevent the viscosity of the sol precursor from being too high, which could lead to pore blockage during subsequent substrate soaking, ethanol is added to adjust the viscosity of the sol precursor.

[0040] In this invention, the organic dispersant is preferably one or more of acetone, acetonitrile, methanol, and petroleum ether; the mass of the organic dispersant is 20-30% of the mass of the sol precursor, more preferably 22-28%. In this invention, the organic dispersant ensures that non-metallic elements are uniformly dissolved in the sol precursor.

[0041] In this invention, the preferred mixing method is to first add a non-metallic source to the pH-adjusted sol precursor, followed by the sequential addition of an organic dispersant and ethanol. In this invention, the preferred addition rate of the organic dispersant is 3–4 mL / s.

[0042] In this invention, the viscosity of the resulting mixture after the pH-adjusted sol precursor is mixed with a non-metallic source, ethanol, and an organic dispersant is preferably 2.4–6.3 mm. 2 / s; The viscosity was measured using a Pinton viscometer, and the capillary inner diameter of the viscometer used in this study was 0.6 mm.

[0043] In this invention, the aging temperature is preferably 60-80°C, more preferably 70°C; the aging time is preferably 12-24 hours, more preferably 16-20 hours.

[0044] This invention involves immersing a porous Ti substrate in an aged sol, removing and drying it, repeating the immersion-drying process multiple times, and then sintering the resulting porous Ti substrate repeatedly immersed in the aged sol to obtain a non-metallic element-doped Ti4O7 electrode. In this invention, the porosity of the porous Ti substrate is preferably 40-65%, more preferably 50-60%. In this invention, the porous Ti substrate is preferably a porous Ti sheet.

[0045] In this invention, before immersing the porous Ti substrate in the aging sol, the present invention preferably performs a pretreatment on the obtained aging sol, the pretreatment preferably including the following steps:

[0046] The porous Ti substrate was subjected to alkali washing, acid washing, and ultrasonic washing in sequence.

[0047] In this invention, the alkaline solution used for alkaline washing is preferably a NaOH solution, and the concentration of the NaOH solution is preferably 5-10 wt%, more preferably 6-8 wt%; the alkaline washing time is preferably 0.5-1 h, more preferably 0.6-0.8 h. This invention removes oil stains from the surface of a porous Ti substrate through alkaline washing.

[0048] In this invention, the acid solution used for pickling is preferably an oxalic acid solution, and the pH value of the oxalic acid solution is preferably 5-10 wt%, more preferably 6-8 wt%; the pickling time is preferably 0.5-1 h, more preferably 0.6-0.8 h. This invention, through pickling, can etch the substrate and increase the adhesion of the substrate surface.

[0049] In this invention, the power of the ultrasonic washing is preferably 60-100 kHz, more preferably 70-80 kHz; the time is preferably 20-40 min, more preferably 30 min.

[0050] In this invention, the immersion time of the porous Ti substrate in the aging sol is preferably 15-30 min, more preferably 20-25 min. In this invention, the drying method is preferably oven drying, and the drying temperature is preferably 60-80°C, more preferably 70°C.

[0051] In this invention, the immersion-drying process is preferably repeated 3 to 7 times, more preferably 4 to 6 times.

[0052] In this invention, the sintering is preferably carried out under an argon atmosphere, and the flow rate of the argon is preferably 60 mL / min.

[0053] In this invention, the sintering temperature is preferably 900–1100℃, more preferably 1000℃; the holding time is preferably 3–5 h, more preferably 4 h. In this invention, the heating rate to the sintering temperature is preferably 5–10℃ / min, 6–8℃ / min. In this invention, under an oxygen-free environment, the titanium source precursor is reduced to Ti4O7 by carbon, generating oxygen vacancies, which can improve the electrode oxidation performance.

[0054] This invention provides a non-metallic element-doped Ti4O7 electrode prepared by the above-described method, comprising a porous titanium substrate and Ti4O7 adhered to the surface and interior of the porous titanium substrate; the Ti4O7 is doped with a non-metallic element, which is one or more of nitrogen, boron, phosphorus, sulfur, and silicon. In this invention, the doping amount of the non-metallic element in the Ti4O7 is preferably 1–5 wt%, more preferably 2–4 wt%.

[0055] The following detailed description of the in-situ doped Ti4O7 electrode and its preparation method provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] The preparation method of a non-metallic element in-situ doped Ti4O7 electrode includes the following steps:

[0058] S1. Preparation of sol precursor:

[0059] 36g polyethylene glycol, 12g tetraethyl titanate, 1.5g acetylacetone and 1.5g methyl methacrylate were mixed evenly and stirred in a 60℃ constant temperature water bath at a speed of 600r / min for 12h to obtain a sol precursor.

[0060] S2. Add non-metallic elements and adjust the pH value:

[0061] Add 1 mol / L nitric acid to the sol precursor to adjust the pH to 6, add 0.12 g melamine to the sol precursor (the mass of nitrogen element is 1% of the mass of tetraethyl titanate), add 10 mL anhydrous ethanol to control the sol viscosity, add 30 mL acetone as a dispersant, stir continuously for 12 h, and finally age the sol at 60 °C for 12 h.

[0062] S3. Electrode Preparation

[0063] Using porous Ti sheets as the substrate, the Ti sheets were first pretreated: alkaline washing with 10% wt NaOH solution for 1 hour to remove oil stains from the substrate surface; acid washing with 10% wt oxalic acid solution for 1 hour to etch the substrate; and finally ultrasonic cleaning. The treated Ti sheets were then immersed in a sol for 15 minutes, dried at 60℃, and this process was repeated 3 times. The sol-immersed Ti sheets were then sintered at high temperature under an argon atmosphere with an argon flow rate of 60 mL / min, a sintering temperature of 900℃, a heating rate of 5℃, and a sintering time of 3 hours. The electrodes were then naturally cooled to obtain the electrodes.

[0064] Example 2

[0065] The preparation method of a non-metallic element in-situ doped Ti4O7 electrode includes the following steps:

[0066] S1. Preparation of sol precursor:

[0067] 36g polyethylene glycol, 12g tetraethyl titanate, 1.5g acetylacetone and 1.5g methyl methacrylate were mixed evenly and stirred in a 60℃ constant temperature water bath at a speed of 600r / min for 12h to obtain a sol precursor.

[0068] S2. Add non-metallic elements and adjust the pH value:

[0069] Add 1 mol / L nitric acid to the sol precursor to adjust the pH to 6. Add 0.36 g of melamine to the sol precursor (the mass of nitrogen element is 3% of the mass of tetraethyl titanate). Add 20 mL of anhydrous ethanol to control the viscosity of the sol. Add 40 mL of acetone as a dispersant. Stir continuously for 12 h. Finally, age the sol at 60 °C for 12 h.

[0070] S3. Electrode Preparation

[0071] Using porous Ti sheets as the substrate, the Ti sheets were first pretreated: alkaline washing with 10% wt NaOH solution for 1 hour to remove oil stains from the substrate surface; acid washing with 10% wt oxalic acid solution for 1 hour to etch the substrate; and finally ultrasonic cleaning. The treated Ti sheets were then immersed in a sol for 30 minutes, dried at 60℃, and this process was repeated 5 times. The sol-immersed Ti sheets were then sintered at high temperature under an argon atmosphere with an argon flow rate of 80 mL / min, a sintering temperature of 1000℃, a heating rate of 5℃, and a sintering time of 4 hours. The electrodes were then naturally cooled to obtain the electrodes.

[0072] Example 3

[0073] The preparation method of a non-metallic element in-situ doped Ti4O7 electrode includes the following steps:

[0074] S1. Preparation of sol precursor:

[0075] 48g of polyethylene glycol, 16g of tetraethyl titanate, 2g of acetylacetone and 2g of methyl methacrylate were mixed evenly and stirred in a 60℃ constant temperature water bath at a speed of 600r / min for 24h to obtain a sol precursor.

[0076] S2. Add non-metallic elements and adjust the pH value:

[0077] Add 1 mol / L nitric acid to the sol precursor to adjust the pH to 6, add 0.8 g melamine to the sol precursor (the mass of nitrogen element is 5% of the mass of tetraethyl titanate), add 30 mL anhydrous ethanol to control the sol viscosity, add 50 mL acetone as a dispersant, stir continuously for 12 h, and finally age the sol at 60 °C for 24 h.

[0078] S3. Electrode Preparation

[0079] Using porous Ti sheets as the substrate, the Ti sheets were first pretreated: alkaline washing with 10% wt NaOH solution for 1 hour to remove oil stains from the substrate surface; acid washing with 10% wt oxalic acid solution for 1 hour to etch the substrate; and finally ultrasonic cleaning. The treated Ti sheets were then immersed in a sol for 30 minutes, dried at 60℃, and this process was repeated 7 times. The sol-immersed Ti sheets were then sintered at high temperature under an argon atmosphere with an argon flow rate of 100 mL / min, a sintering temperature of 1100℃, a heating rate of 5℃, and a sintering time of 5 hours. The electrodes were then naturally cooled to obtain the electrodes.

[0080] Comparative Example 1

[0081] Compared with Example 2, melamine was not added, but all other operations were the same, resulting in a Ti4O7 electrode.

[0082] Comparative Example 2

[0083] Compared with Example 2, the masses of polyethylene glycol, tetraethyl titanate, acetylacetone, and methyl methacrylate were 24g, 24g, 1.5g, and 1.5g, respectively.

[0084] Comparative Example 3

[0085] Compared with Example 2, melamine was replaced with Ce(NO3)3 to obtain a rare earth element-doped Ti4O7 electrode.

[0086] Test case

[0087] Using Examples 1, 2, 3, Comparative Examples 1, 2, and 3 as anodes, an oxidation experiment of perfluorooctanoic acid (PFOA) was conducted in a circulating filtration mode at a flow rate of 100 mL / min and a current density of 30 mA / cm². 2 The reaction time was 60 min, and the yield of ·OH was tested using coumarin as the target substance.

[0088] The curve showing the change in PFOA content over time is as follows: Figure 1 As shown in Table 1, the PFOA degradation rate, reaction rate, and ·OH yield are all PFOA degradation rates.

[0089] Table 1. PFOA degradation rate, reaction rate, and ·OH yield

[0090]

[0091] As can be seen from Table 1, the (Ti) prepared in Example 1 1-x N xThe degradation rate of PFOA by the 4O7 (X = 1%) anode was 96.3%, with a reaction rate constant of 5.86 × 10⁻⁶. -2 min -1 The (Ti) prepared in Example 2 1-x N x The degradation rate of PFOA by the 4O7 (X = 3%) anode was 98.1%, with a reaction rate constant of 6.73 × 10⁻⁶. -2 min -1 The (Ti) prepared in Example 3 1-x N x The degradation rate of PFOA by the 4O7 (X = 5%) anode was 96.3%, with a reaction rate constant of 5.94 × 10⁻⁶. -2 min -1 .

[0092] At a voltage of 5.4V:

[0093] The (Ti) prepared in Example 1 1-x N x The yield of ·OH at the anode of 4O7 (X = 1%) was 4.08 × 10⁻⁶. -8 mol / min / cm -2 The (Ti) prepared in Example 2 1-x N x The yield of ·OH at the anode of 4O7 (X = 3%) is 4.25 × 10⁻⁶. -8 mol / min / cm -2 The (Ti) prepared in Example 3 1-x N x The yield of ·OH at the anode of 4O7 (X = 5%) is 4.13 × 10⁻⁶. -8 mol / min / cm -2 .

[0094] The electrode prepared in Comparative Example 1 showed a PFOA degradation rate of 86.2% and a reaction rate of 1.5 × 10⁻⁶. -2 min -1 Compared to Example 2, the degradation rate and reaction rate decreased, and the ·OH yield was 2.82 × 10⁻⁶ at a voltage of 5.4 V. -8 mol / min / cm 2 The decrease compared to Example 2 indicates that the addition of non-metallic elements can greatly increase the yield of ·OH in the electrode and improve its catalytic activity.

[0095] The electrode prepared in Comparative Example 2 showed a PFOA degradation rate of 76.3% and a reaction rate of 5.66 × 10⁻⁶. -2 min -1Compared to Example 2, the degradation rate and reaction rate decreased, and the ·OH yield was 2.59 × 10⁻⁶ at a voltage of 5.4 V. -8 mol / min / cm 2 The decrease compared to Example 2 indicates that when the amount of polyethylene glycol (carbon source) added is insufficient, Ti cannot be completely reduced to Ti4O7, resulting in an impure product. Even when doped with non-metallic elements, its oxidation effect is not as good as that of alcohol Ti4O7.

[0096] The electrode prepared in Comparative Example 3 showed a PFOA degradation rate of 94.9% and a reaction rate of 2.47 × 10⁻⁶. -2 min -1 Compared to Example 2, the degradation rate and reaction rate decreased, and the ·OH yield was 4.03 × 10⁻⁶ at a voltage of 5.4 V. -8 mol / min / cm 2 The oxidation capacity of Ti4O7 prepared by non-metallic element doping is lower than that prepared by metal doping, indicating that the oxidation capacity is better than that prepared by metal doping.

[0097] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a non-metallic element-doped Ti4O7 electrode, comprising the following steps: A sol precursor is obtained by mixing polyethylene glycol, tetraethyl titanate, acetylacetone, and methyl methacrylate; the mass ratio of polyethylene glycol to tetraethyl titanate is 18~30:6~10. The pH of the sol precursor is adjusted to 5-6. The pH-adjusted sol precursor is mixed with a non-metallic source, ethanol, and an organic dispersant, and then aged to obtain an aged sol. The non-metallic source is a nitrogen source, specifically melamine and / or urea. The mass of the non-metallic element in the non-metallic source is 1-5% of the mass of tetrabutyl titanate. The porous Ti substrate is immersed in the aged sol, removed and dried, and the immersion-drying process is repeated multiple times. The porous Ti substrate that has been immersed in the aged sol multiple times is sintered in an oxygen-free environment to obtain a non-metallic element in-situ doped Ti4O7 electrode.

2. The preparation method according to claim 1, characterized in that, The mass ratio of tetraethyl titanate to acetylacetone is 6~10:0.5~1; The molar ratio of tetrabutyl titanate to methyl methacrylate is 6~10:0.5~1.

3. The preparation method according to claim 1, characterized in that, The mass of the ethanol is 10-20% of the mass of the sol precursor.

4. The preparation method according to claim 1, characterized in that, The organic dispersant is one or more of acetone, acetonitrile, methanol, and petroleum ether; The mass of the organic dispersant is 20-30% of the mass of the sol precursor.

5. The preparation method according to claim 1, characterized in that, The aging temperature is 60~80℃, and the time is 12~24h.

6. The preparation method according to claim 1, characterized in that, The time for a single immersion of the porous Ti substrate in the aging sol is 15-30 minutes; the immersion-drying process is repeated 3-7 times.

7. The preparation method according to claim 1 or 6, characterized in that, The sintering temperature is 900~1100℃, and the holding time is 3~5h.

8. The in-situ doped Ti4O7 electrode prepared by the preparation method according to any one of claims 1 to 7 comprises a porous titanium substrate and Ti4O7 attached to the surface and interior of the porous titanium substrate; wherein the Ti4O7 is doped with a non-metallic element, wherein the non-metallic element is nitrogen.

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