CN108452805B - A kind of NiTiO3/TiO2 catalyst for photolyzing water to produce hydrogen and its preparation method and use - Google Patents

Abstract

The invention relates to a NiTiO for photolyzing water to produce hydrogen₃/TiO₂Catalyst, preparation method and application thereofThe catalyst is made of Ni (NO)₃)₂And HTNT. The invention also provides a preparation method of the catalyst, the photocatalyst is prepared by in-situ reaction through a hydrothermal method, and the prepared catalyst is a uniform one-dimensional nanotube. The NiTiO prepared by the method₃/TiO₂The nanotube catalyst has stable structure and property, can be repeatedly used for catalyzing the hydrogen production reaction by photolysis, and still has good stability after being recycled for multiple times.

Description

A kind of NiTiO3/TiO2 catalyst for photolyzing water to produce hydrogen and its preparation method and use

technical field

The invention belongs to the field of semiconductor photocatalysis, and in particular relates to a NiTiO ₃ /TiO ₂ nanocomposite material catalyst for photolyzing water to produce hydrogen and a preparation method and application thereof.

Background technique

The massive consumption of non-renewable fossil energy has made energy depletion and serious environmental pollution a major problem facing the world today. Seeking environmentally friendly renewable energy has become the best choice to solve the energy crisis and environmental problems. Hydrogen has attracted widespread attention as the cleanest energy source. The direct use of sunlight to split water to produce hydrogen is considered to be an effective way to solve the energy crisis and environmental pollution problems. The use of sunlight to split water is inseparable from the catalytic action of photocatalysts. The catalysts found so far generally suffer from problems such as poor stability, low photoelectric conversion efficiency, greater environmental harm, high synthesis cost, and photocorrosion, which cannot be applied on a large scale. Titanium dioxide has the characteristics of low cost, stable chemical properties, and no pollution, and is considered to be a promising photocatalyst. However, the wider valence band of titanium dioxide has limited light absorption and utilization. Generally, co-catalysts are added to increase the absorption of visible light to improve its light absorption and utilization efficiency.

In order to improve the catalytic efficiency of the photocatalyst, CN103872174A (application number 201210552885.7) provides a preparation method of Au-modified _TiO2 nanorod array photoanode material with visible light absorption characteristics. The surface and bottom of TiO ₂ are co-modified with Au quantum dots, which increases the absorption range of TiO ₂ in the visible light range and improves the photo-water splitting efficiency. CN102513129A (application number 201110393837.3) provides a method for preparing a photocatalytic TiO ₂ /Cu ₂ O composite thin film, and the photocatalytic hydrogen production performance is improved by modifying Pt. However, the above catalysts need to use precious metals, and the preparation cost is high. In addition, most of these catalysts cannot be recycled and cannot achieve the purpose of environmental protection and economy.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the deficiencies of the prior art, and to provide a NiTiO ₃ /TiO ₂ catalyst for photo-splitting water to produce hydrogen and a preparation method thereof. and other advantages, the preparation method has mild reaction conditions and simple operation steps.

In order to achieve the above object, the present invention provides the following technical solutions:

A NiTiO ₃ /TiO ₂ catalyst for photo-splitting water to produce hydrogen is a nano-composite material of NiTiO ₃ and TiO ₂ .

According to the present invention, the molar ratio of NiTiO ₃ /TiO ₂ in the NiTiO ₃ /TiO ₂ catalyst may be (0-0.055):1 and not 0; preferably (0.005-0.045):1; more preferably (0.01) -0.030):1; more preferably (0.012-0.025):1.

According to the present invention, the TiO ₂ phase in the NiTiO ₃ /TiO ₂ catalyst is an anatase phase.

According to the present invention, the NiTiO ₃ /TiO ₂ catalyst is a one-dimensional nanotube. The length of the nanotubes may be between 100-800 nm; the inner diameter may be 3-5 nm.

According to the present invention, the NiTiO ₃ /TiO ₂ catalyst has a larger specific surface area, and the specific surface area can be 80-150 m ² /g.

The catalyst of the present invention has the following advantages:

(1) The NiTiO ₃ /TiO ₂ catalyst has higher photocatalytic efficiency than TiO ₂ . Among them, NiTiO ₃ contained in the catalyst can effectively improve the photocatalytic efficiency of TiO ₂ nanotubes;

(2) The NiTiO ₃ /TiO ₂ catalyst can increase the hydrogen production rate of TiO ₂ nanotubes by at least 15 times, and its hydrogen production rate is at least 60 times higher than that of P25 powder;

(3) The NiTiO ₃ /TiO ₂ catalyst has a stable structure, and no photoetching phenomenon is found during use;

(4) The NiTiO ₃ /TiO ₂ catalyst can be recycled for more than 4 times, for example, it can be recycled for at least 5 times, and the effect of photo-splitting water to produce hydrogen has no obvious attenuation.

The present invention also provides a method for preparing the above-mentioned NiTiO ₃ /TiO ₂ catalyst, wherein the NiTiO ₃ /TiO ₂ catalyst uses protonated titanate nanotubes (hereinafter referred to as "HTNT") as precursors, and utilizes hydrothermal in-situ reaction method prepared.

According to the present invention, the method comprises the following preparation steps:

1) prepare HTNT, it comprises the following steps:

1a) hydrothermally react TiO ₂ with an alkaline solution; after the reaction is completed, separate titanate nanotubes;

1b) Washing the titanate nanotubes of step 1a) with water to remove excess alkali; then washing with acid solution to obtain protonated titanate nanotubes; washing with water again, washing with organic solvents, and drying to obtain HTNTs ;

2) Preparation of NiTiO ₃ /TiO ₂ catalyst precursor, which includes: mixing HTNT and Ni(NO ₃ ) ₂ solution, stirring, then adding alkaline solution to adjust the pH of the reaction solution, continuing to stir, filtering, and then using H ₂ O and organic Solvent cleaning and drying to obtain NiTiO ₃ /TiO ₂ catalyst precursor;

3) Annealing treatment to prepare a NiTiO ₃ /TiO ₂ catalyst, which includes: calcining the above-mentioned NiTiO ₃ /TiO ₂ catalyst precursor to obtain a NiTiO ₃ /TiO ₂ catalyst.

In step 1a), preferably, the alkaline solution can be an aqueous NaOH solution; the concentration of the alkaline solution can be 5-10 mol/L;

Preferably, the TiO ₂ can be nano powder;

Preferably, the ratio (g:mL) of the mass of the TiO ₂ to the volume of the alkaline solution may be (2.0-3.5): (40-100), preferably (2.5-3.0): (60-90), For example, 2.5:80;

Preferably, the temperature of the hydrothermal reaction is 120-300°C, preferably 160-240°C, as an illustrative example, the temperature of the hydrothermal reaction is 160°C;

Preferably, the time of the hydrothermal reaction may be 1.5-24h, and as an illustrative example, the time of the hydrothermal reaction is 24h.

Preferably, the separation can be suction filtration using a vacuum pump;

In step 1b), the water is preferably distilled water;

Preferably, the acid solution can be an aqueous nitric acid solution with an arbitrary ratio of concentrated nitric acid and water; the concentration of the aqueous nitric acid solution can be 0.001mol/L-0.1mol/L, preferably 0.005mol/L-0.05mol/L, For example, 0.01mol/L;

Preferably, the organic solvent is not particularly limited as long as it does not react with the product. Preferably, the solvent is a solvent inert to the reaction reagents. As an illustrative example, the organic solvent may be selected from nitrile solvents (such as acetonitrile), aromatic hydrocarbon solvents (such as benzene, toluene), alcohol solvents (such as methanol, ethanol, isopropanol, n-propanol), ether solvents (such as diethyl ether), one or more of ester solvents (such as ethyl acetate), halogenated hydrocarbon solvents (such as dichloromethane, carbon tetrachloride). Further preferably, the organic solvent is ethanol.

In step 2), the concentration of the Ni(NO ₃ ) ₂ solution may be 0.0001-0.1 mol/L, preferably 0.001-0.015 mol/L;

Preferably, the molar ratio of Ni(NO ₃ ) ₂ to HTNT may be 0:1 to 0.05:1, preferably 0.01:1 to 0.02:1, more preferably 0.018:1;

Preferably, the reaction time of the HTNT and Ni(NO ₃ ) ₂ can be 5-24h, as an exemplary example, the reaction time is 24h;

Preferably, the alkali solution can be one or more of ammonia water, NaHCO ₃ aqueous solution, and Na ₂ CO ₃ aqueous solution, for example, ammonia water can be used;

Preferably, adding lye to adjust the pH of the reaction solution to be 9-11;

Preferably, after the pH of the reaction solution is adjusted to 9-11, stirring can be continued for more than 1 hour, for example, stirring can be continued for 2 hours, 5 hours or 10 hours;

Preferably, the organic solvent used for washing in the step 2) has the definition as described in the above step 1).

In step 3), preferably, the calcination temperature can be 300-600°C, preferably 350-450°C, as an exemplary example, the calcination temperature is 450°C;

Preferably, the calcination time may be more than 1 hour, for example, may be 2 hours.

The present invention also provides the use of the above-mentioned _{NiTiO 3} / _{TiO 2} catalyst, which can be used to catalyze the photo-splitting of water to produce hydrogen.

Beneficial effects of the present invention:

1. The NiTiO ₃ /TiO ₂ catalyst of the present invention has a stable structure and no photoetching phenomenon is found. After being used for more than 4 times, the effect of photolyzing water to produce hydrogen has no obvious attenuation.

2. The NiTiO ₃ /TiO ₂ catalyst exhibits a unique one-dimensional nanotube-like structure, which can significantly improve the photo-utilization efficiency of the catalyst, thereby improving the efficiency of TiO ₂ photo-splitting water for hydrogen production.

3. The preparation of NiTiO ₃ /TiO ₂ catalyst is carried out at a lower temperature, and no toxic precious metals are introduced as co-catalysts during the reaction process, which reduces energy consumption and does not seriously affect the environment.

Description of drawings

Figure 1 is the XRD pattern of the S1-S9 sample; wherein, (a) is the XRD pattern of the S1-S9 sample, and (b) and (c) are partial enlarged images.

Figure 2 is the XRD pattern of the S9 sample.

Figures 3(a) and (b) are TEM images of S0 and S5, respectively.

FIG. 4 is a graph showing the variation of hydrogen production with time for S0-S9 samples in Example 11. FIG.

FIG. 5 is a graph showing the variation of the hydrogen production amount of the S0-S9 samples in Example 11 with the NiTiO ₃ content in the catalyst.

Figure 6 is a graph of the cyclic catalytic hydrogen production of the S5 catalyst.

Detailed ways

The photocatalytic efficiency of the NiTiO ₃ /TiO ₂ catalyst for photo-splitting water to produce hydrogen of the present invention is measured by the following photocatalytic test method:

i) Add 0.01-1 g of the NiTiO ₃ /TiO ₂ catalyst of the present invention into the photocatalytic reactor in the photocatalytic system, and then add 100 mL of pure water or an aqueous solution of a hole sacrificial agent with a volume fraction of 5% to 50%, The hole sacrificing agent can be methanol, ethanol, acetic acid, lactic acid and the like.

ii) Start the vacuum pump connected to the photocatalytic system and start stirring at the same time to remove the air in the system until the pressure value reaches a negative one atmosphere and no bubbles emerge from the liquid surface in the reactor.

iii) Start the magnetron glass air pump to promote the gas flow in the system, so that the gas is dispersed evenly, place the xenon lamp light source simulating natural light above the reactor, and turn on the xenon lamp to start the photocatalytic reaction.

iv) Use the gas chromatography that comes with the photocatalytic system to periodically sample and analyze the gas generated by the water splitting in the system, sample once every 1 hour, and sample and analyze each sample 10 times to determine the type and content of the gas products in the photocatalytic water splitting reaction.

The present invention will be further described below in conjunction with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the contents described in the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the limited scope of the present invention.

Unless otherwise specified, the raw materials and reagents used in the examples are all commercially available materials.

The XRD of the example samples was characterized using a miniflex-600 powder diffractometer.

Transmission electron microscopy of the example samples was characterized using a scanning transmission electron microscope Tecnai G2F20.

The Ni and Ti content analysis and test of the samples of the examples were characterized by using an Ultima 2 inductively coupled full-spectrum plasma spectrometer.

Example 1 (Preparation of HTNT)

Weigh 320 g of NaOH and dissolve it in 1000 mL of distilled water under stirring at room temperature to prepare an 8 mol/L NaOH solution. 2.5g of TiO ₂ nanopowder and 80mL of the above-mentioned NaOH solution were added to ten 100mL reaction kettles respectively, and the reaction kettles were moved to a blast drying oven for hydrothermal reaction at 160°C for 24h. After the reaction, the titanate nanotubes are obtained by suction filtration with a vacuum pump.

The hydrothermally prepared titanate nanotubes were washed three times with distilled water to remove excess NaOH. Then wash with 0.01 mol/L nitric acid for 10 times, so that the sodium in the titanate nanotubes can be fully replaced by the hydrogen in the nitric acid, that is, the titanate is protonated. After washing 5 times with distilled water and 3 times with ethanol, HTNT was obtained after drying, which was named S0.

Example 2

Mix 1 g of HTNT synthesized in Example 1 with 40 mL of 0.001 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and then add aqueous ammonia solution dropwise to it to adjust the pH of the solution, until the pH of the solution is 9-11, continue After stirring for 5 h, the mixture was filtered by a vacuum pump, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, named S1.

Example 3

Mix 1 g of HTNT with 40 mL of 0.002 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and then add aqueous ammonia solution dropwise to adjust the pH of the solution until the pH of the solution is 9-11, continue stirring for 5 h, and use a vacuum pump to pump filtered, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, which was named S2.

Example 4

Mix 1 g of HTNT synthesized in Example 1 with 40 mL of 0.003 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and then add aqueous ammonia solution dropwise to it to adjust the pH of the solution, until the pH of the solution is 9-11, continue After stirring for 5 h, the mixture was filtered by a vacuum pump, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, named S3.

Example 5

Mix 1 g of HTNT synthesized in Example 1 with 40 mL of 0.004 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and then add aqueous ammonia solution dropwise to it to adjust the pH of the solution, until the pH of the solution is 9-11, continue After stirring for 5 h, the mixture was filtered by a vacuum pump, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, named S4.

Example 6

Mix 1 g of HTNT synthesized in Example 1 with 40 mL of 0.005 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and then add aqueous ammonia solution dropwise to adjust the pH of the solution until the pH of the solution is 9-11, and continue After stirring for 5 h, the mixture was filtered by a vacuum pump, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, named S5.

Example 7

Mix 1 g of HTNT synthesized in Example 1 with 40 mL of 0.006 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and then add aqueous ammonia solution dropwise to it to adjust the pH of the solution, until the pH of the solution is 9-11, continue After stirring for 5 h, the mixture was filtered by a vacuum pump, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, named S6.

Example 8

Mix 1 g of HTNT synthesized in Example 1 with 40 mL of 0.007 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and add aqueous ammonia solution dropwise to it to adjust the pH of the solution until the pH of the solution is 9-11, continue After stirring for 5 h, the mixture was filtered by a vacuum pump, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, named S7.

Example 9

Mix 1 g of HTNT synthesized in Example 1 with 40 mL of 0.008 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and then add aqueous ammonia solution dropwise to it to adjust the pH of the solution, until the pH of the solution is 9-11, continue After stirring for 5 h, the mixture was filtered by a vacuum pump, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, named S8.

Example 10

Mix 1 g of HTNT synthesized in Example 1 with 40 mL of 0.015 mol/L Ni(NO ₃ ) ₂ solution, stir magnetically for 24 h, and then add aqueous ammonia solution dropwise to adjust the pH of the solution until the pH of the solution is 9-11, and continue After stirring for 5 h, the mixture was filtered by a vacuum pump, washed repeatedly with H ₂ O and ethanol, and dried. The suction filtered product was annealed in a tube furnace. After calcination at 450 °C for 2 h, a one-dimensional tubular NiTiO ₃ /TiO ₂ photocatalyst was obtained, named S9. Example 11 (elemental analysis and photocatalytic hydrogen production test)

Weigh 0.1 g of catalysts S0-S9 prepared in Examples 1-10 above to test their photocatalytic hydrogen production efficiency using the above-mentioned test method. The test results are shown in Figures 4 and 5.

It can be seen from Figure 4 that the hydrogen production of the catalyst increases with time, while the hydrogen production of pure TiO ₂ (S0) hardly changes with time; and with the increase of NiTiO ₃ content, its production The amount of hydrogen increases with time; moreover, within a certain range, such as the molar ratio of NiTiO ₃ to TiO ₂ (x:1), when x is between 0 and 0.0177, with the increase of NiTiO ₃ content , its hydrogen production also increased.

It can be seen from Figure 5 that the hydrogen production rate of the NiTiO ₃ /TiO ₂ catalyst increases first and then decreases with the increase of NiTiO ₃ content, and the hydrogen production rate reaches the highest when the molar ratio of NiTiO ₃ to TiO ₂ is 0.0177:1.

The catalysts S0-S9 prepared in the above-mentioned examples 1-10 were tested by ICP content analysis, and the results were shown in Table 1.

Table 1 Molar ratio of _NiTiO3 to _TiO2 in S1-S9 samples

Example 12 (catalyst cycle catalytic hydrogen production test)

The S5 catalyst was filtered and recovered after the catalytic hydrogen production test. After drying, it was directly used for the next catalytic hydrogen production test. The test results are shown in Figure 6.

It can be seen from Figure 6 that the catalyst has undergone five photocatalytic cycles, and the hydrogen production effect does not decrease significantly, the catalyst performance is relatively stable, and it can be recycled for many times, and the catalytic activity has almost no change.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (17)

1. a NiTiO ₃ /TiO ₂ catalyst for photo-splitting water to produce hydrogen, characterized in that the catalyzer is the nanocomposite material of NiTiO ₃ and TiO ₂ ; in the catalyzer, the mol ratio of NiTiO ₃ /TiO ₂ is (0- 0.055): 1 and not 0; The NiTiO ₃ /TiO ₂ catalyst is a one-dimensional nanotube; The length of the nanotubes is between 100-800 nm; the inner diameter is 3-5 nm. 2 . The NiTiO ₃ /TiO ₂ catalyst according to claim 1 , wherein the molar ratio of NiTiO ₃ /TiO ₂ in the catalyst is (0.005-0.045):1. 3 . 3 . The NiTiO ₃ /TiO ₂ catalyst according to claim 2 , wherein the molar ratio of NiTiO ₃ /TiO ₂ in the catalyst is (0.01-0.030):1. 4 . 4 . The NiTiO ₃ /TiO ₂ catalyst according to claim 3 , wherein the molar ratio of NiTiO ₃ /TiO ₂ in the catalyst is (0.012-0.025):1. 5 . 5 . The NiTiO ₃ /TiO ₂ catalyst according to claim 1 , wherein the TiO ₂ phase in the NiTiO ₃ /TiO ₂ catalyst is an anatase phase. 6 . 6 . The NiTiO ₃ /TiO ₂ catalyst according to claim 1 , wherein the NiTiO ₃ /TiO ₂ catalyst has a specific surface area of 80-150 m ² /g. 7 . 7. A method for preparing the NiTiO ₃ /TiO ₂ catalyst according to any one of claims 1 to 6, wherein the catalyst uses protonated titanate nanotube HTNT as a precursor, and utilizes hydrothermal in situ Preparation by the method of reaction; The method specifically comprises the following preparation steps: 1) Preparation of protonated titanate nanotubes HTNT, which includes the following steps: 1a) hydrothermally react _TiO2 with an alkaline solution; after the reaction is completed, separate titanate nanotubes; 1b) Wash the titanate nanotubes in step 1a) with water to remove excess alkali; then wash with acid solution to obtain protonated titanate nanotubes; use water again, wash with organic solvent, and dry to obtain HTNTs ; 2) Preparation of NiTiO ₃ /TiO ₂ catalyst precursor, which includes: mixing HTNT and Ni(NO ₃ ) ₂ solution, stirring, then adding alkaline solution to adjust the pH of the reaction solution, continuing to stir, filtering, and then using H ₂ O and organic Solvent cleaning and drying to obtain NiTiO ₃ /TiO ₂ catalyst precursor; 3) Annealing treatment to prepare a NiTiO ₃ /TiO ₂ catalyst, which includes: calcining the above-mentioned NiTiO ₃ /TiO ₂ catalyst precursor to obtain a NiTiO ₃ /TiO ₂ catalyst. 8. A method for preparing the NiTiO ₃ /TiO ₂ catalyst according to claim 7, wherein in step 1a), the alkaline solution is an aqueous NaOH solution; The concentration of the alkaline solution is 5-10 mol/L. 9. A method for preparing the NiTiO ₃ /TiO ₂ catalyst according to claim 7, wherein in step 1a), the TiO ₂ is nanopowder; The ratio of the mass of the TiO ₂ to the volume of the alkaline solution is (2.0~3.5) g:(40~100) mL. 10 . The preparation method of the NiTiO ₃ /TiO ₂ catalyst according to claim 7 , wherein the temperature of the hydrothermal reaction is 120-300° C. 11 . 11. A method for preparing the NiTiO ₃ /TiO ₂ catalyst according to claim 7, wherein in step 1b), the water is distilled water; The acid solution is an aqueous nitric acid solution with an arbitrary ratio of concentrated nitric acid and water. 12 . A method for preparing a NiTiO ₃ /TiO ₂ catalyst according to claim 7 , wherein in step 2), the concentration of the Ni(NO ₃ ) ₂ solution is 0.0001-0.1 mol/L. 13 . 13. A method for preparing a NiTiO ₃ /TiO ₂ catalyst as claimed in claim 7, wherein in step 2), the alkaline solution is one of ammonia water, NaHCO ₃ aqueous solution, and Na ₂ CO ₃ aqueous solution or variety; Add lye to adjust the pH of the reaction solution to 9-11. 14 . The preparation method of the NiTiO ₃ /TiO ₂ catalyst according to claim 7 , wherein, in step 3), the calcination temperature is 300-600° C. 15 . 15. A method for preparing a NiTiO ₃ /TiO ₂ catalyst according to claim 11, wherein in step 1a), the ratio of the mass of the TiO ₂ to the volume of the alkaline solution is (2.5~3.0) g : (60~90) mL; The temperature of the hydrothermal reaction is 160-240°C; In step 1b), the concentration of the nitric acid aqueous solution is 0.001-0.1 mol/L; The organic solvent is selected from one or more of nitrile solvents, aromatic hydrocarbon solvents, alcohol solvents, ether solvents, ester solvents, and halogenated hydrocarbon solvents; In step 2), the concentration of the Ni(NO ₃ ) ₂ solution is 0.001-0.015mol/L; Described lye is ammoniacal liquor; In step 3), the calcination temperature is 350-450°C. 16. A method for preparing a NiTiO ₃ /TiO ₂ catalyst according to claim 15, wherein in step 1a), the ratio of the mass of the TiO ₂ to the volume of the alkaline solution is 2.5 g: 80 mL; The hydrothermal reaction temperature is 160°C; In step 1b), the concentration of the nitric acid aqueous solution is 0.005mol/L-0.05mol/L; The organic solvent is ethanol; In step 2), the molar ratio of Ni(NO ₃ ) ₂ to HTNT is 0.018:1; In step 3), the calcination temperature is 450°C. 17. The use of the catalyst according to any one of claims 1 to 6, wherein the _NiTiO3 / _TiO2 catalyst is used to catalyze the photolysis of water to produce hydrogen.

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