Titanium dioxide phase junction material, preparation method thereof and application of titanium dioxide phase junction material in water electrolysis hydrogen evolution reaction

Abstract

The invention relates to a hydrogen evolution reaction catalyst, in particular to a titanium dioxide phase junction material, a preparation method thereof and application of the titanium dioxide phase junction material in an electrolytic water hydrogen evolution reaction, and the preparation method comprises the following steps: S1, putting a foam titanium substrate into an alkaline solution to carry out a hydrothermal reaction, and washing and drying a reaction product; s2, calcining the reaction product obtained in the step S1 for the first time to obtain a titanium oxide; and S3, carrying out secondary calcination on the titanium oxide obtained in the step S2, and carrying out doping induced phase change to obtain the titanium dioxide phase junction material. Compared with the prior art, the preparation method has the advantages that the problems that heterojunction has interface defects and phase junction is difficult to prepare in a hydrogen evolution reaction catalyst based on titanium dioxide in the prior art are solved, and the preparation of the phase junction catalytic material which is simple in technological process and capable of effectively saving energy is realized; the catalyst can be used for catalytic hydrogen evolution reaction under electrolyte conditions with different pH values.

Description

Technical Field

[0001] The present invention relates to a hydrogen evolution reaction catalyst, and particularly to a titanium dioxide phase junction material, a preparation method thereof, and an application thereof in the hydrogen evolution reaction of electrolytic water. Background Art

[0002] In today's era, the world is facing the problems of energy crisis and environmental pollution. Searching for and developing renewable clean energy is an urgent task. Hydrogen, as a clean and pollution-free energy carrier with a high energy density, is expected to gradually replace the position of traditional fossil fuels. Electrochemical water splitting for hydrogen production can be combined with other intermittent energy systems (such as wind energy and solar energy) to achieve a sustainable and environmentally friendly hydrogen production process. However, in the actual water splitting process, the hydrogen evolution reaction (HER) at the cathode is hindered by a large overpotential, resulting in low overall electrolysis efficiency. To solve this problem, it is necessary to introduce efficient catalysts to accelerate the reaction kinetics and lower the reaction energy barrier. Currently, the commercially available hydrogen evolution reaction catalyst is the platinum-carbon (Pt / C) catalyst, which exhibits ultra-high catalytic efficiency, but the scarcity and high cost of precious metals hinder its large-scale industrial application. Therefore, developing inexpensive and efficient transition metal-based electrocatalysts is an important task to promote the development of modern clean energy systems.

[0003] In the past few decades, extensive research has been conducted on transition metal-based materials, but it has also been found that their intrinsic electrocatalytic efficiency is much lower than that of Pt / C. Therefore, it is necessary to optimize the structure design of transition metal-based materials to improve their catalytic ability. Heterostructures are beneficial for optimizing the intrinsic catalytic activity of transition metal-based materials due to their adjustable electronic properties and synergistic effects between components. Generally, in order to avoid the formation of too many defects at the interface, which may affect the material properties, there needs to be a good lattice matching degree between the two components of the heterostructure.

[0004] For example, Chinese Patent CN113718278A discloses a preparation method of a transition metal phosphide / nitride heterojunction catalyst and efficient electrolytic water hydrogen evolution research. Using cobalt, nickel, iron and other powder nitrates as raw materials, through electrodeposition, hydrothermal synthesis or chemical vapor deposition techniques, nickel, iron or cobalt single metal or two-metal oxide nanostructures (nanowires, nanosheets, etc.) arrays are prepared on nickel foam, cobalt, iron, copper and carbon cloth, etc.; these nanowire arrays are nitrided to obtain highly conductive nanoporous materials; taking this as a growth carrier, nickel, iron or cobalt-based transition metal phosphide nanostructures are grown in-situ to prepare the final heterojunction catalyst. However, the structure of the heterojunction is an interface formed by the contact of two or more materials with different chemical compositions. Therefore, there are differences in lattice mismatch, interface energy, etc. at the heterojunction, which will further affect the performance and function of the material.

[0005] Phase junction is a special form of heterojunction, and the two components are homoepitaxial materials. Compared with traditional heterojunctions, the components in the phase junction have a higher lattice matching degree, closer interfacial bonding, and a more perfect energy band structure. In short, the good component coordination in the phase junction is conducive to the further improvement of the electrocatalytic performance. However, the construction of the phase junction still faces problems such as complex process, unstable structure, and low catalytic efficiency, and its application is greatly limited. Therefore, it is still necessary to study transition metal catalyst materials based on the phase junction to provide excellent catalytic performance and low production cost. Summary of the Invention

[0006] The purpose of the present invention is to provide a titanium dioxide phase junction material, its preparation method, and its application in the electrolytic water hydrogen evolution reaction to solve at least one of the above problems, so as to solve the problems in the prior art that the hydrogen evolution reaction catalyst based on transition metals has interface defects in the heterojunction and difficulties in preparing the phase junction. The preparation of a phase junction catalytic material with a simple process flow and effective energy saving is realized, and the catalyst can catalyze the hydrogen evolution reaction under different pH electrolyte conditions.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The first aspect of the present invention discloses a preparation method of a titanium dioxide phase junction material, which includes the following steps:

[0009] S1: Place the titanium foam substrate into an alkaline solution for hydrothermal reaction, wash and dry the reaction product;

[0010] S2: Calcinate the reaction product obtained in step S1 once to obtain titanium oxide (titanium dioxide);

[0011] S3: Calcinate the titanium oxide obtained in step S2 twice and induce phase transformation by doping to obtain a titanium dioxide phase junction material.

[0012] Preferably, the titanium foam substrate is pretreated before use: ultrasonically cleaned and dried; more specifically, the ultrasonic cleaning is: sequentially using dilute hydrochloric acid (0.1-1 mol / L), acetone, ethanol, and deionized water as cleaning agents, and ultrasonically cleaning for 5-30 min respectively; during the drying process, the temperature is 50-90 °C.

[0013] Preferably, in step S1, the alkaline solution is a 0.5-3 mol / L sodium hydroxide solution.

[0014] Preferably, in step S1, the temperature of the hydrothermal reaction is 100-220 °C, and the time is 1-36 h.

[0015] Preferably, in step S1, the washing is: using deionized water and / or ethanol as a detergent; during the drying process, the temperature is 50-90 °C, and the time is 2-24 h.

[0016] Preferably, in step S2, the first calcination is carried out under the protection of an inert atmosphere, at a temperature of 400 - 700 °C and for a time of 2 - 8 h.

[0017] Preferably, in step S3, the second calcination is carried out under the protection of an inert atmosphere, at a temperature of 400 - 700 °C and for a time of 2 - 8 h.

[0018] More preferably, the inert atmosphere is nitrogen or argon.

[0019] Preferably, ammonium fluoride is added during the second calcination process, and doping-induced phase transformation is achieved through nitrogen atoms and fluorine atoms. The addition amount of ammonium fluoride should be adjusted according to the dosage of titanium oxide, and it can usually be controlled in the range of 0 - 200 mg and not 0 mg, preferably controlled at 40 - 70 mg.

[0020] Preferably, the ammonium fluoride is arranged on the intake side, and the titanium dioxide is arranged on the exhaust side.

[0021] The second aspect of the present invention discloses a titanium dioxide phase junction material prepared by using any of the above methods.

[0022] The third aspect of the present invention discloses an application of the above-mentioned titanium dioxide phase junction material in the electrolysis water hydrogen evolution reaction. This phase junction material can be used in the range of pH from 0 to 14.

[0023] The working principle of the present invention is as follows:

[0024] The present invention uses commercial titanium foam as the substrate. First, titanium oxide is prepared as a precursor by a hydrothermal method and an in-situ oxidation method, and then nitrogen and fluorine doping-induced phase transformation is carried out to construct a phase junction electrocatalyst material loaded on the substrate. This catalyst material has a three-dimensional self-supporting structure grown in-situ and a unique nanoparticle array morphology, which tightly combines the substrate and the loaded structure and has abundant pores, ensuring a fast mass transfer and electron transfer efficiency.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The phase junction electrocatalyst material prepared by the present invention not only has excellent electrocatalytic performance and a simple preparation process, but also has a wide range of raw material sources, low cost, environmental protection and non-toxicity. It can carry out stable and efficient hydrogen evolution reactions under different electrolyte conditions, maintaining extremely low reaction energy consumption, and has great potential value in large-scale hydrogen production applications.

[0027] Among them, taking the titanium dioxide phase junction material (prepared with titanium foam as the raw material) as an example for illustration:

[0028] 1) The prepared titanium dioxide phase junction material has a three-dimensional self-supporting structure and a porous nanoparticle array morphology, which can ensure the full exposure of active sites and efficient mass transfer and rapid charge transfer during the catalytic process.

[0029] 2) For the first time, a method of inducing phase transformation by dual doping of nitrogen and fluorine atoms was developed to in-situ transform a single-phase titanium dioxide precursor into a dual-phase titanium dioxide phase junction material, obtaining strong interfacial coupling and optimized electronic structure.

[0030] 3) The doping of nitrogen and fluorine dual atoms not only promotes the formation of a nanoparticle array structure with abundant active sites, but also effectively improves the adsorption free energy of the phase junction to reactive hydrogen species. Brief Description of the Drawings

[0031] Figure 1 Scanning electron microscope images (SEM) of the phase junction material prepared in Example 1 (a) and the material prepared in Comparative Example 1 (b);

[0032] Figure 2 Transmission electron microscope images (TEM) of the phase junction material prepared in Example 1, where (a) is at low magnification and (b) is at high magnification;

[0033] Figure 3 X-ray diffraction pattern (XRD) of the phase junction material prepared in Example 1;

[0034] Figure 4 Linear sweep voltammogram of the phase junction material prepared in Example 1 (HER in 1.0 mol / L potassium hydroxide electrolyte at a scan rate of 5 mV per second);

[0035] Figure 5 Current density-time curve of the phase junction material prepared in Example 1 (HER in 1.0 mol / L potassium hydroxide electrolyte at a current density of 10 mA cm -2 );

[0036] Figure 6 [[ID=??]] Linear sweep voltammogram of the phase junction material prepared in Example 1 (HER in 0.5 mol / L sulfuric acid electrolyte at a scan rate of 5 mV per second);

[0037] Figure 7 Current density-time curve of the phase junction material prepared in Example 1 (HER in 0.5 mol / L sulfuric acid electrolyte at a current density of 10 mA cm -2 );

[0038] Figure 8 It should be noted that there seems to be a formatting issue with the line breaks in the original text around line 28 and 38 where the superscript for the current density unit "cm" is not properly formatted. I've tried to translate as accurately as possible based on the provided text. Also, there is a question mark in the ID for the line with "Linear sweep voltammogram of the phase junction material prepared in Example 1 (HER in 0.5 mol / L sulfuric acid electrolyte at a scan rate of 5 mV per second);" which might be a mistake in the original. If you have any further clarifications, please let me know.Linear sweep voltammogram of the phase junction material prepared in Example 1 (HER in 1.0 mol / L PBS buffer solution at a scanning rate of 5 mV per second);

[0039] Figure 9 Current density-time curve of the phase junction material prepared in Example 1 (HER in 1.0 mol / L PBS buffer solution with a current density of 10 mA cm -2 ). Detailed implementation mode

[0040] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] In the following description, if not otherwise specified, the reagents used are conventional commercially available products, and the methods used are well-known means in the art.

[0042] Example 1

[0043] A preparation method of a titanium dioxide phase junction electrocatalyst (rutile phase: anatase phase = 1:1.08) includes the following steps:

[0044] 1) Use 0.5M dilute hydrochloric acid, acetone, ethanol, and deionized water to ultrasonically clean the blank titanium foam (1 cm × 0.5 cm) for 15 minutes each to remove the surface oxide layer and impurities, then place it in an oven at 60 °C for 4 hours of drying, and then use it as a substrate;

[0045] 2) Add 0.8 mg of sodium hydroxide to 20 mL of deionized water, stir to fully dissolve the sodium hydroxide to obtain a 1M sodium hydroxide solution;

[0046] 3) Transfer the above sodium hydroxide solution to a reaction kettle with a capacity of 50 mL;

[0047] 4) Place the treated titanium foam substrate into the reaction kettle containing the sodium hydroxide solution, set the hydrothermal temperature to 200 °C, and the hydrothermal time to 18 hours;

[0048] 5) Wash the titanium foam after the hydrothermal reaction three times with deionized water and / or ethanol respectively, and then place it in an oven at 60 °C for 12 hours of drying.

[0049] 6) Calcinate the dried titanium foam in a N2 atmosphere for 3 hours at a calcination temperature of 550 °C to obtain an anatase phase titanium dioxide precursor.

[0050] 7) Calcinate the anatase phase titanium dioxide precursor again in a N2 atmosphere. Place 50 mg of ammonium fluoride powder upstream of the gas flow and place the anatase titanium dioxide precursor downstream of the gas flow. The calcination temperature is 500 °C and the time is 2 hours to obtain an anatase / rutile titanium dioxide phase junction material.

[0051] When the prepared anatase / rutile titanium dioxide phase junction electrocatalyst is used to catalyze the hydrogen evolution reaction under the condition of pH value from 0 to 6, the specific steps are as follows: The prepared anatase / rutile titanium dioxide phase junction electrocatalyst is used as the working electrode, saturated calomel is used as the reference electrode, and a carbon rod is used as the counter electrode. The electrochemical performance of HER is tested in a nitrogen-saturated electrolyte, including linear sweep voltammetry test and time-current density test.

[0052] When used to catalyze the hydrogen evolution reaction under the condition of pH value from 6 to 14, the specific steps are as follows: The prepared anatase / rutile titanium dioxide phase junction electrocatalyst is used as the working electrode, Hg / HgO is used as the reference electrode, and a carbon rod is used as the counter electrode. The electrochemical performance of HER is tested in a nitrogen-saturated electrolyte, including linear sweep voltammetry test and time-current density test.

[0053] Comparative Example 1

[0054] It is basically the same as the steps of Example 1, except that in this comparative example, ammonium fluoride is not added during the second calcination; the finally obtained is a pure anatase phase titanium dioxide electrocatalyst.

[0055] Figure 1 Scanning electron microscope images (SEM) of the anatase / rutile titanium dioxide phase junction electrocatalyst prepared by doping-induced phase transformation (Example 1, left (a) figure) and the pure anatase phase titanium dioxide electrocatalyst prepared without doping (Comparative Example 1, that is, the anatase phase titanium dioxide precursor, right (b) figure). From Figure 1 It can be seen that the anatase phase titanium dioxide precursor presents a two-dimensional nanosheet array morphology and has a rich pore structure. After doping-induced phase transformation, the anatase / rutile titanium dioxide phase junction electrocatalyst has a nanoparticle morphology in-situ cleaved from the nanosheets, while retaining the porous structure characteristics of the precursor. These nanoparticles are interconnected to form a tight interface. This structure promotes the formation of tight bonding and a perfect energy band structure, thereby greatly enhancing the electrocatalytic activity of the titanium dioxide phase junction electrocatalyst.

[0056] Figure 2 Transmission electron microscope images (TEM) of the prepared anatase / rutile titanium dioxide phase junction electrocatalyst. From Figure 2As can be seen from (a) and (b), the titanium dioxide phase junction material has a nanoparticle structure, and the particles are interconnected to form an interface, which is consistent with the SEM image. In the high-magnification TEM, it can be seen that there are two lattice fringes in the titanium dioxide phase junction electrocatalyst, and there is an obvious interface between the two, proving that the dual doping of nitrogen and fluorine has successfully induced the occurrence of a phase change, resulting in the formation of a phase junction. The doped atoms and the formed phase junction interface jointly play a role in regulating the electronic structure of the system, promoting the improvement of the electrocatalytic performance of this phase junction material.

[0057] Figure 3 XRD patterns of the prepared anatase / rutile titanium dioxide phase junction electrocatalyst and the anatase phase titanium dioxide precursor. Figure 3 As can be seen, the diffraction peaks of the anatase phase titanium dioxide precursor are located at 25.3°, 36.9°, 37.8°, 38.6°, 48.0°, 53.9°, 55.1°, 62.1°, 62.7° and 68.8°, which correspond to the anatase phase of titanium dioxide. In contrast, the anatase / rutile titanium dioxide phase junction material shows new diffraction peaks at 27.4°, 36.1°, 39.2°, 41.2°, 44.1°, 54.3°, 56.6°, 62.7°, 64.0°, 65.5°, 69.0° and 69.8°, and these peaks originate from the rutile phase of titanium dioxide. In addition, the peaks at 35.0°, 38.4°, 40.2°, 52.9° and 62.7° are attributed to the titanium foam substrate. The strongest diffraction peak of the titanium dioxide phase junction material at 25.3° shows an obvious negative shift compared with that of pure anatase phase titanium dioxide, proving that the doped atoms have been successfully introduced into titanium dioxide, leading to a change in the lattice spacing.

[0058] Figure 4 HER linear sweep voltammogram of the prepared anatase / rutile titanium dioxide phase junction electrocatalyst in 1.0 mol / L potassium hydroxide electrolyte (pH = 14) at a scanning rate of 5 mV per second. Figure 4 As can be seen, the titanium dioxide phase junction electrocatalyst has excellent HER performance under alkaline conditions. At a current density of 10 mA cm –2 , the HER overpotential is only 74 mV.

[0059] Figure 5 HER current density-time curve of the prepared anatase / rutile titanium dioxide phase junction electrocatalyst with a stable current density of 10 mA cm –2 in 1.0 mol / L potassium hydroxide electrolyte (pH = 14). Figure 5It can be seen that the titanium dioxide phase junction electrocatalyst has very stable electrocatalytic cycling performance. After continuous operation for 200 hours, there is almost no current decay, and stable and efficient HER applications under alkaline conditions can be achieved.

[0060] Figure 6 HER linear sweep voltammogram of the prepared anatase / rutile titanium dioxide phase junction electrocatalyst in 0.5 mol / L sulfuric acid electrolyte (pH = 0) at a scanning rate of 5 mV per second. Figure 6 It can be seen that the titanium dioxide phase junction electrocatalyst also has excellent HER performance under acidic conditions. At a current density of 10 mA cm –2 the HER overpotential is only 80 mV.

[0061] Figure 7 HER current density-time curve of the prepared anatase / rutile titanium dioxide phase junction electrocatalyst with a stable current density of 10 mA cm –2 in 0.5 mol / L sulfuric acid electrolyte (pH = 0). Figure 7 It can be seen that the titanium dioxide phase junction electrocatalyst also has stable HER performance under acidic conditions. After 100 hours of cycling, only a slight current decay occurs, and stable and efficient HER applications under acidic conditions can be achieved.

[0062] Figure 8 HER linear sweep voltammogram of the prepared anatase / rutile titanium dioxide phase junction electrocatalyst in 1.0 mol / L PBS buffer (pH = 7.4) at a scanning rate of 5 mV per second. Figure 8 It can be seen that the titanium dioxide phase junction electrocatalyst also has excellent HER performance under neutral conditions. At a current density of 10 mA cm –2 the HER overpotential is only 142 mV.

[0063] Figure 9 HER current density-time curve of the prepared anatase / rutile titanium dioxide phase junction electrocatalyst with a stable current density of 10 mA cm –2 in 1.0 mol / L PBS buffer (pH = 7.4). Figure 9 It can be seen that the titanium dioxide phase junction electrocatalyst also has stable HER performance under neutral conditions. After 100 hours of cycling, only a slight current decay occurs, and stable and efficient HER applications under neutral conditions can be achieved.

[0064] In summary, in this embodiment, commercial foamed titanium is used as the substrate. First, anatase titanium dioxide precursor is prepared by the seed method and in-situ oxidation method, and then nitrogen and fluorine doping are used to induce phase transformation to construct anatase / rutile titanium dioxide phase junction electrocatalyst material supported on the substrate. This catalyst material has a three-dimensional self-supporting structure grown in-situ and a unique nanoparticle array morphology, which enables tight binding between the substrate and the load, and has abundant pores, ensuring fast mass transfer and electron transfer efficiency. This catalyst material is a titanium-based material, which is environmentally friendly, non-toxic, and easy to recycle. In addition, the strong interface coupling between the two phases in this catalyst material significantly changes the electronic structure at the interface, regulating the adsorption free energy of the catalyst for hydrogen active intermediates.

[0065] These advantages enable it to exhibit excellent electrocatalytic hydrogen evolution performance under different electrolyte conditions (for example, in 1.0 M KOH solution with pH = 14, the HER overpotential of the titanium dioxide phase junction material at a current density of 10 mA cm –2 : η KOH = 74 mV; in 0.5 M H2SO4 solution with pH = 1, the HER overpotential of the titanium dioxide phase junction material at a current density of 10 mA cm –2 : η H2SO4 = 80 mV; in 1.0 M PBS solution, the HER overpotential of the titanium dioxide phase junction material at a current density of 10 mA cm –2 : η PBS = 142 mV), and it can maintain extremely high stability under different electrolyte conditions (for example, in 1.0 M KOH solution, the titanium dioxide phase junction electrocatalyst shows almost no decay after operating at a current density of 10 mA cm –2 for 200 h; in 0.5 M H2SO4 solution and 1.0 M PBS solution, the titanium dioxide phase junction electrocatalyst can stably operate at a current density of 10 mA cm –2 for more than 100 h).

[0066] The titanium dioxide phase junction electrocatalyst material prepared in this embodiment not only has excellent electrocatalytic performance and simple preparation process, but also has wide raw material sources, low cost, environmental friendliness, non-toxicity, can carry out stable and efficient hydrogen evolution reaction under different electrolyte conditions, maintain extremely low reaction energy consumption, and has ultra-long stability, showing great potential value in large-scale hydrogen production applications.

[0067] Example 2

[0068] A preparation method of a titanium dioxide phase junction electrocatalyst (rutile phase: anatase phase = 1:0.52) includes the following steps:

[0069] 1) The blank titanium foam (1 cm × 0.5 cm) was sonicated in 0.5 M dilute hydrochloric acid, acetone, ethanol, and deionized water for 15 min respectively to remove the surface oxide layer and impurities, and then placed in an oven at 60 °C for 4 h of drying, and subsequently used as a substrate;

[0070] 2) 0.8 mg of sodium hydroxide was added to 20 mL of deionized water, and stirred to fully dissolve the sodium hydroxide to obtain a 1 M sodium hydroxide solution;

[0071] 3) The above sodium hydroxide solution was transferred to a reaction kettle with a capacity of 50 mL;

[0072] 4) The treated titanium foam substrate was placed in the reaction kettle containing the sodium hydroxide solution, and the hydrothermal temperature was set at 200 °C and the hydrothermal time was 18 h;

[0073] 5) The titanium foam after the hydrothermal reaction was washed three times with deionized water and / or ethanol respectively, and then placed in an oven at 60 °C for 12 h of drying.

[0074] 6) The dried titanium foam was calcined in a N2 atmosphere for 3 h at a calcination temperature of 550 °C to obtain anatase-phase titanium dioxide precursor.

[0075] 7) The anatase-phase titanium dioxide precursor was calcined again in a N2 atmosphere. 40 mg of ammonium fluoride powder was placed upstream of the gas flow, and the anatase titanium dioxide precursor was placed downstream of the gas flow. The calcination temperature was 500 °C and the time was 2 h to obtain an anatase / rutile titanium dioxide phase composite material.

[0076] Example 3

[0077] Preparation method of a titanium dioxide phase composite electrocatalyst (rutile phase: anatase phase = 1:0.66), comprising the following steps:

[0078] 1) The blank titanium foam (1 cm × 0.5 cm) was sonicated in 0.5 M dilute hydrochloric acid, acetone, ethanol, and deionized water for 15 min respectively to remove the surface oxide layer and impurities, and then placed in an oven at 60 °C for 4 h of drying, and subsequently used as a substrate;

[0079] 2) 0.8 mg of sodium hydroxide was added to 20 mL of deionized water, and stirred to fully dissolve the sodium hydroxide to obtain a 1 M sodium hydroxide solution;

[0080] 3) The above sodium hydroxide solution was transferred to a reaction kettle with a capacity of 50 mL;

[0081] 4) The treated titanium foam substrate was placed in the reaction kettle containing the sodium hydroxide solution, and the hydrothermal temperature was set at 200 °C and the hydrothermal time was 18 h;

[0082] 5) Wash the hydrothermally reacted titanium foam three times with deionized water and / or ethanol, and then place it in an oven at 60 °C and dry for 12 h.

[0083] 6) Calcinate the dried titanium foam in an N2 atmosphere for 3 h at a calcination temperature of 550 °C to obtain anatase-phase titanium dioxide precursor.

[0084] 7) Calcinate the anatase-phase titanium dioxide precursor again in an N2 atmosphere. Place 70 mg of ammonium fluoride powder upstream of the gas flow and place the anatase titanium dioxide precursor downstream of the gas flow. The calcination temperature is 500 °C and the time is 2 h to obtain an anatase / rutile titanium dioxide phase composite material.

[0085] For the parameters in the preparation process of the metal oxide phase composite material involved in the above examples, they can all be selected according to the actual experimental conditions and requirements. For example:

[0086] In step 1), the pretreatment process is as follows: first ultrasonically clean the foam metal or metal sheet, and then dry it. Among them, the ultrasonic cleaning process is as follows: use acetone, ethanol, and deionized water as cleaning agents in sequence and ultrasonically clean for 5 - 30 min (such as 10 min, 20 min, 30 min) respectively; during the drying process, the temperature is 50 - 90 °C (such as 55 °C, 65 °C, 75 °C).

[0087] In step 2), the alkali solution used is not limited to sodium hydroxide (for example, it can be potassium hydroxide), and the concentration of the alkali solution is 0.5 - 3 mol / L (such as 1.2 mol / L, 1.8 mol / L, 2.4 mol / L).

[0088] In step 3), during the hydrothermal reaction process, the temperature is 100 - 220 °C (such as 130 °C, 180 °C, 200 °C), and the time is 1 - 36 h (such as 5 h, 18 h, 30 h).

[0089] In step 4), during the washing process, water and / or ethanol are used as detergents; during the drying process, the temperature is 50 - 90 °C (such as 60 °C, 70 °C, 80 °C), and the time is 2 - 24 h (such as 10 h, 15 h, 18 h).

[0090] In step 5), during the calcination process, the atmosphere is an inert atmosphere such as N2 or Ar, the temperature is 400 - 700 °C (such as 450 °C, 550 °C, 650 °C), and the time is 2 - 8 h (such as 3 h, 5 h, 7 h).

[0091] In step 6), during the calcination process, the mass of ammonium fluoride powder added is 0 - 200 mg and not 0 mg (such as 50 mg, 100 mg, 150 mg); the atmosphere is an inert atmosphere such as N2 or Ar, the temperature is 400 - 700 °C (such as 500 °C, 600 °C, 700 °C), and the time is 2 - 8 h (such as 3 h, 5 h, 7 h).

[0092] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. Obviously, those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of a titanium dioxide phase junction material, characterized in that, It includes the following steps: S1: Place the titanium foam substrate into an alkali solution for hydrothermal reaction, wash and dry the reaction product; S2: Calcinate the reaction product obtained in step S1 once to obtain titanium oxide; S3: Calcinate the titanium oxide obtained in step S2 twice and induce doping-induced phase transformation to obtain a titanium dioxide phase junction material.

2. The preparation method of a titanium dioxide phase junction material according to claim 1, characterized in that, In step S1, the alkali solution is a sodium hydroxide solution with a concentration of 0.5 - 3 mol / L.

3. The preparation method of a titanium dioxide phase junction material according to claim 1, characterized in that, In step S1, the temperature of the hydrothermal reaction is 100 - 220 °C, and the time is 1 - 36 h.

4. The preparation method of a titanium dioxide phase junction material according to claim 1, characterized in that, In step S2, the first calcination is carried out under the protection of an inert atmosphere, the temperature is 400 - 700 °C, and the time is 2 - 8 h.

5. The preparation method of a titanium dioxide phase junction material according to claim 1, characterized in that, In step S3, the second calcination is carried out under the protection of an inert atmosphere, the temperature is 400 - 700 °C, and the time is 2 - 8 h.

6. The preparation method of a titanium dioxide phase junction material according to claim 5, characterized in that, During the second calcination process, ammonium fluoride is added to achieve doping-induced phase transformation through nitrogen atoms and fluorine atoms.

7. The preparation method of a titanium dioxide phase junction material with different phase ratios according to claim 6, characterized in that, The addition amount of the ammonium fluoride is 0 - 200 mg and not 0 mg.

8. The preparation method of a titanium dioxide phase junction material according to claim 6, characterized in that, The ammonium fluoride is arranged on the intake side, and the titanium oxide is arranged on the exhaust side.

9. A titanium dioxide phase junction material, characterized in that, Prepared by using the method according to any one of claims 1 - 8.

10. Application of the titanium dioxide phase junction material according to claim 9 as a catalyst in the electrolytic water hydrogen evolution reaction.

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