CN111893511A - Fe2O3/MXene photocathode and preparation method and application thereof - Google Patents

Abstract

The invention relates to Fe₂O₃A/MXene photocathode and a preparation method and application thereof. The Fe₂O₃the/MXene photocathode comprises a substrate and Fe sequentially loaded on the substrate₂O₃Films and Mxene films; the thickness of the Mxene film is 0.9-1.3 μm. The invention provides Fe₂O₃The photocathode has the advantages of visible light response and the like, and has high photocurrent density and photon-generated carrier transport efficiency, and high efficiency of photolysis of water to produce hydrogen; and the raw materials are cheap and easy to obtain.

Description

Fe2O3/MXene photocathode and preparation method and application thereof

Technical Field

The invention relates to the technical field of nano material preparation and hydrogen production catalysts, and particularly relates to Fe₂O₃A/MXene photocathode and a preparation method and application thereof.

Background

With the progress of human society and the development of global industry, the situation of shortage of primary fossil energy such as petroleum and coal mines is increasingly severe, the energy problem becomes one of the difficulties in the sustainable development roads of all countries in the world, the search for renewable and recyclable clean energy is urgent, and the renewable and pollution-free combustion process of hydrogen energy makes the clean energy stand out. Hydrogen production by fossil fuel and photocatalytic hydrogen production are the main methods for hydrogen production at present, but both the two technologies need to consume extra substances to achieve the purpose, and the water photolysis technology is concerned about hydrogen production by directly utilizing solar energy, so that the water photolysis technology becomes one of the technologies which have the greatest application value for relieving energy crisis and environmental pollution.

The technique of photolyzing water requires the preparation of photocathode materials, known as Fe₂O₃Providing an encouraging means for sustainable solar energy collection

(Annamalai A, Subramanian A, Kang U, et al. activation of Heatutho aspects for Solar Water Splitting: Effect of FTO Deformation [ J ]. Journal of physical chemistry C,2015,119(7): 3810-. However, the rapid charge recombination due to the short diffusion length and the low charge separation efficiency after photon absorption limits its wide application.

Therefore, a Fe having a high photocatalytic efficiency was developed₂O₃The photocathode has important research significance and application value in expanding the application of the photocathode.

Disclosure of Invention

The invention aims to overcome the existing Fe₂O₃The defect or deficiency that the photocathode diffusion length is short and the charge separation efficiency is low after photon absorption is provided₂O₃a/MXene photocathode. The invention provides Fe₂O₃The photocathode has the advantages of visible light response and the like, and has high photocurrent density and photon-generated carrier transport efficiency, and high efficiency of photolysis of water to produce hydrogen; and the raw materials are cheap and easy to obtain.

It is another object of the present invention to provide the above Fe₂O₃A preparation method of an MXene photocathode.

Another object of the present invention is to provide Fe as described above₂O₃The application of the/MXene photocathode in the field of photoelectrochemistry.

In order to achieve the purpose, the invention adopts the following technical scheme:

fe₂O₃the/MXene photocathode comprises a substrate and Fe sequentially loaded on the substrate₂O₃Films and Mxene films; the thickness of the Mxene film is 0.9-1.3 μm.

The Mxene material is a two-dimensional material which can provide more channels for the movement of ions, greatly improves the movement speed of the ions and has the metal conductivity of transition metal carbide.

The invention is Fe loaded on a substrate₂O₃The film is used as a supporting carrier and then is loaded with Mxene film, and the Mxene material can improve Fe₂O₃Short pore diffusion length (2-4nm) of the film shows good photosensitivity, thereby enhancing photoelectrochemical properties and eliminating Fe₂O₃The limitation of the film layer structure improves the transport efficiency of photon-generated carriers in the photocathode and the efficiency of water hydrogen production by photolysis.

The invention provides Fe₂O₃the/MXene photocathode has the advantages of response to visible light, high photocurrent density, high transport efficiency of photon-generated carriers and high efficiency of photolysis of water to produce hydrogen; and the raw materials are cheap and easy to obtain.

Fe₂O₃The thickness of the film may be conventional.

Preferably, the Fe₂O₃The film has a thickness of 0.8 to 1.5 μm.

Preferably, the substrate is FTO conductive glass or ITO conductive glass.

More preferably, the substrate is FTO conductive glass.

Preferably, the Mxene in the Mxene film is n-type.

Fe as described above₂O₃The preparation method of the/MXene photocathode comprises the following steps:

s1: deposition of Fe on a substrate using hydrothermal reaction₂O₃Precursor, then heat treatment to obtain Fe₂O₃A film;

s2: in Fe₂O₃Coating Mxene solution on the film, and drying to obtain the Fe₂O₃a/MXene photocathode.

The invention leads Fe to be prepared by a hydrothermal method₂O₃The precursor (beta-FeOOH) is deposited on the substrate, so that a stable base can be formed; then carrying out heat treatment to obtain Fe₂O₃Simultaneously, possible other impurities generated by hydrothermal growth are removed, and more stable and pure Fe is formed₂O₃And further improve the stability of the support carrier. At the same time, Fe can be enhanced₂O₃The connection and the conductivity between the photoelectric conversion layer and the substrate obviously reduce the resistance and improve the stability and the photocurrent density of the photocathode. In addition, after hydrothermal treatment and heat treatment, the substrate is not affected basically, for example, when FTO glass is used as the substrate, the good conductivity and light transmittance can still be maintained.

The preparation method has the advantages of simple operation, controllable conditions and good repeatability; fe prepared by the preparation method of the invention₂O₃the/MXene photocathode has the characteristics of high stability and response to visible light, high photocurrent density and photon-generated carrier transport efficiency, and high efficiency of photolysis of water to produce hydrogen; and the raw materials are cheap and easy to obtain.

Preferably, the process of S1 is as follows:

s11: adding nitrate into the solution containing the ferric salt to obtain a mixed solution; the pH value of the solution containing the trivalent ferric salt is 8-10;

s12: placing the substrate in the mixed solution, carrying out hydrothermal reaction, taking out the substrate, and drying;

s13: and annealing the substrate obtained in the step S12 at 500-550 ℃, and sintering at a high temperature of 700-800 ℃ to obtain the high-temperature-resistant high-performance ceramic.

Fe was obtained by annealing in S13₂O₃Film, then high-temperature sintering is carried out to further promote Fe₂O₃Connection and conduction between film and substrateThe electrical property, the steadiness is better.

More preferably, the nitrate in S11 is NaNO₃Or KNO₃One or two of them.

More preferably, the ferric iron source in S12 is ferric chloride.

More preferably, the pH is adjusted in S11 using an acidic solution (e.g., hydrochloric acid, dilute sulfuric acid, etc.).

More preferably, the temperature of the hydrothermal reaction in S12 is 100-120 ℃ and the time is 6-8 h.

The Mxene solution can be prepared by methods conventional in the art, and the present invention also provides a method for preparing the Mxene solution.

Preferably, the Mxene solution in S2 is prepared by the following procedure:

s21: for MAX-Ti₃AlC₂Etching, centrifuging and taking precipitate;

s22: dissolving the precipitate in organic solution, performing ultrasonic treatment, and centrifuging to obtain precipitate;

s23: adding water into the precipitate, crushing, centrifuging and taking supernatant to obtain the Mxene solution.

Organic solvents conventional in the art, such as ethanol, may be used in the present invention.

More preferably, S21 is etched using a mixed solution of lithium fluoride and hydrochloric acid.

Preferably, the concentration of the MXene solution in S2 is 1 g/15-20 mL.

Fe as described above₂O₃The application of the/MXene photocathode in the field of photoelectrochemistry is also within the protection scope of the invention.

Preferably, the Fe₂O₃The application of the/Mxene photocathode in photoelectrochemical water decomposition hydrogen production.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides Fe₂O₃the/MXene photocathode has the advantages of high stability, visible light response and the like, and has high photocurrent density, high transport efficiency of photon-generated carriers and high efficiency of photolysis of water to produce hydrogen; and the raw materials are cheap and easy to obtain.

The preparation method provided by the invention is simple to operate, controllable in conditions and good in repeatability.

Drawings

FIG. 1 is Fe provided in example 3 of the present invention₂O₃A surface scanning electron microscope image of (a);

FIG. 2 is Fe provided in example 3 of the present invention₂O₃Surface scanning electron microscope image of/MXene film;

FIG. 3 is Fe provided in example 3 of the present invention₂O₃Cross-sectional scanning electron micrographs of;

FIG. 4 is Fe provided in example 3 of the present invention₂O₃A cross-sectional scanning electron microscope image of the/MXene film;

FIG. 5 shows Fe provided in example 3 of the present invention₂O₃X-ray diffraction patterns of (a);

FIG. 6 is Fe provided in example 3 of the present invention₂O₃X-ray diffraction pattern of/MXene film;

FIG. 7 is a graph of photocurrent density versus bias voltage curve;

FIG. 8 is a graph of photocurrent density versus time curves;

fig. 9 is an ultraviolet-visible absorption spectrum diagram.

Detailed Description

The invention is further illustrated by the following examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention. Experimental procedures without specific conditions noted in the examples below, generally according to conditions conventional in the art or as suggested by the manufacturer; the raw materials, reagents and the like used are, unless otherwise specified, those commercially available from the conventional markets and the like. Any insubstantial changes and substitutions made by those skilled in the art based on the present invention are intended to be covered by the claims.

Example 1

This example provides a Fe₂O₃The preparation process of the/MXene photocathode is as follows.

(1)Fe₂O₃Preparation of films

0.4g of FeCl₃.6H₂O was placed in a 20mL hydrothermal kettle, then 10mL deionized water was added and stirring was continued until completely dissolved therein. Then, a 1mol/L HCl solution was prepared, and the pH of the solution was adjusted to 1.5 with the HCl solution. 0.85g NaNO was added to the solution₃And continuously stirring until the mixture is completely dissolved. Then a piece of cleaned FTO conductive glass (1cm by 2.5cm) was placed and covered. The hydrothermal kettle is further subjected to hydrothermal reaction for 6 hours at 100 ℃. The FTO was then cooled to room temperature and washed three times with deionized water and ethanol, respectively. The FTO was finally dried at 60 ℃ for 6 hours. Finally, annealing the dried FTO at 550 ℃ for 5 hours, then sintering at high temperature to 800 ℃ for 2 hours, and cooling to room temperature for later use. Obtained Fe₂O₃The thickness of the film was about 0.8. mu.m.

(2) Preparation of MXene

2g of lithium fluoride was stirred with 9mol/L of 40mL hydrochloric acid in a polytetrafluoroethylene beaker for 30 minutes. 2g of MAX-Ti₃AlC₂Slowly added to the teflon beaker and the temperature was set to 35 ℃ with continuous stirring for 24 hours. And then, centrifuging the obtained reaction liquid by 4 centrifuge tubes, pouring out supernatant liquid after centrifugation, adding 40ml of deionized water into precipitates of the 4 centrifuge tubes respectively, shaking up, performing ultrasonic treatment for 10 minutes, taking out, continuing centrifugation, and repeating for several times until the pH value of the poured liquid after centrifugation is 5. Then 40ml of ethanol was added to each of 4 centrifuge tubes and sonicated for 1 hour, followed by centrifugation, and the lower layer precipitate was collected. 20ml of deionized water was added to each of the 4 collected centrifuge tubes, and after disruption in a cell disruptor for 1 hour, the supernatant, i.e., the desired MXene solution, was collected by centrifugation for 3 minutes.

(3)Fe₂O₃Preparation of/MXene film

Spin-coating 5. mu.L of MXene liquid on the resulting Fe with a pipette gun₂O₃Drying the film at 60 ℃ to obtain the required Fe₂O₃a/MXene photocathode material. The MXene films had a thickness of about 0.9. mu.m.

Example 2

The embodiment is providedFor supplying a kind of Fe₂O₃The preparation process of the/MXene photocathode is as follows.

(1)Fe₂O₃Examples of production of films

0.4g of FeCl₃.6H₂O was placed in a 20mL hydrothermal kettle, then 10mL deionized water was added and stirring was continued until completely dissolved therein. Then, a 1mol/L HCl solution was prepared, and the pH of the solution was adjusted to 1.5 with the HCl solution. 0.85g NaNO was added to the solution₃And continuously stirring until the mixture is completely dissolved. Then a piece of cleaned FTO conductive glass (1cm by 2.5cm) was placed and covered. The hydrothermal kettle is further subjected to hydrothermal reaction for 6 hours at 100 ℃. The FTO was then cooled to room temperature and washed three times with deionized water and ethanol, respectively. The FTO was finally dried at 60 ℃ for 6 hours. Finally, annealing the dried FTO at 550 ℃ for 4 hours, then sintering at high temperature to 800 ℃ for 2 hours, and cooling to room temperature for later use. Obtained Fe₂O₃The thickness of the film was about 1.0. mu.m.

(2) Preparation of MXene

2g of lithium fluoride was stirred with 9mol/L of 40mL hydrochloric acid in a polytetrafluoroethylene beaker for 30 minutes. 2g of MAX-Ti₃AlC₂Slowly added to the teflon beaker and the temperature was set to 35 ℃ with continuous stirring for 24 hours. And then, centrifuging the obtained reaction liquid by 4 centrifuge tubes, pouring out supernatant liquid after centrifugation, adding 40ml of deionized water into precipitates of the 4 centrifuge tubes respectively, shaking up, performing ultrasonic treatment for 10 minutes, taking out, continuing centrifugation, and repeating for several times until the pH value of the poured liquid after centrifugation is 5. Then 40ml of ethanol was added to each of 4 centrifuge tubes and sonicated for 1 hour, followed by centrifugation, and the lower layer precipitate was collected. 20ml of deionized water was added to each of the 4 collected centrifuge tubes, and after 2 hours of disruption in a cell disruptor, the supernatant, i.e., the desired MXene solution, was collected by centrifugation for 3 minutes.

(3)Fe₂O₃Preparation of/MXene film

Spin coating 10. mu.L of MXene liquid on the resulting Fe with a pipette gun₂O₃On a film, then drying at 60 ℃ to obtain the requiredFe₂O₃a/MXene photocathode material. The MXene films had a thickness of about 1.0. mu.m.

Example 3

This example provides a Fe₂O₃The preparation process of the/MXene photocathode is as follows.

(1)Fe₂O₃Preparation of films

0.4g of FeCl₃.6H₂O was placed in a 20mL hydrothermal kettle, then 10mL deionized water was added and stirring was continued until completely dissolved therein. Then, a 1mol/L HCl solution was prepared, and the pH of the solution was adjusted to 1.5 with the HCl solution. 0.85g NaNO was added to the solution₃And continuously stirring until the mixture is completely dissolved. Then a piece of cleaned FTO conductive glass (1cm by 2.5cm) was placed and covered. The hydrothermal kettle is further subjected to hydrothermal reaction for 6 hours at 100 ℃. The FTO was then cooled to room temperature and washed three times with deionized water and ethanol, respectively. The FTO was finally dried at 60 ℃ for 6 hours. Finally, annealing the dried FTO at 550 ℃ for 3 hours, then sintering at high temperature to 800 ℃ for 2 hours, and cooling to room temperature for later use. Obtained Fe₂O₃The thickness of the film was about 1.2. mu.m.

(2) Preparation of MXene

2g of lithium fluoride are stirred with 9M 40ml of hydrochloric acid in a polytetrafluoroethylene beaker for 30 minutes. 2g of MAX-Ti₃AlC₂Slowly added to the teflon beaker and the temperature was set to 35 ℃ with continuous stirring for 24 hours. And then, centrifuging the obtained reaction liquid by 4 centrifuge tubes, pouring out supernatant liquid after centrifugation, adding 40ml of deionized water into precipitates of the 4 centrifuge tubes respectively, shaking up, performing ultrasonic treatment for 10 minutes, taking out, continuing centrifugation, and repeating for several times until the pH value of the poured liquid after centrifugation is 5. Then 40ml of ethanol was added to each of 4 centrifuge tubes and sonicated for 1 hour, followed by centrifugation, and the lower layer precipitate was collected. 20ml of deionized water was added to each of the 4 collected centrifuge tubes, and after disruption in a cell disruptor for 1 hour, the supernatant, i.e., the desired MXene solution, was collected by centrifugation for 3 minutes.

(3)Fe₂O₃/MXene filmPreparation of

Spin coating 15 μ L MXene solution in the resulting Fe by pipette gun₂O₃Drying the film at 60 ℃ to obtain the required Fe₂O₃a/MXene photocathode material. The MXene films had a thickness of about 1.1 μm.

Example 4

This example provides a Fe₂O₃The preparation process of the/MXene photocathode is as follows.

(1)Fe₂O₃Preparation of films

0.4g of FeCl₃.6H₂O was placed in a 20mL hydrothermal kettle, then 10mL deionized water was added and stirring was continued until completely dissolved therein. Then, a 1mol/L HCl solution was prepared, and the pH of the solution was adjusted to 1.5 with the HCl solution. 0.85g NaNO was added to the solution₃And continuously stirring until the mixture is completely dissolved. Then a piece of cleaned FTO conductive glass (1cm by 2.5cm) was placed and covered. The hydrothermal kettle is further subjected to hydrothermal reaction for 6 hours at 100 ℃. The FTO was then cooled to room temperature and washed three times with deionized water and ethanol, respectively. The FTO was finally dried at 60 ℃ for 6 hours. Finally, annealing the dried FTO at 550 ℃ for 2 hours, sintering at high temperature to 800 ℃ for 2 hours, and cooling to room temperature for later use. Obtained Fe₂O₃The thickness of the film was about 1.5. mu.m.

(2) Preparation of MXene

2g of lithium fluoride are stirred with 9mol/L of 40ml hydrochloric acid in a polytetrafluoroethylene beaker for 30 minutes. 2g of MAX-Ti₃AlC₂Slowly added to the teflon beaker and the temperature was set to 35 ℃ with continuous stirring for 24 hours. And then, centrifuging the obtained reaction liquid by 4 centrifuge tubes, pouring out supernatant liquid after centrifugation, adding 40ml of deionized water into precipitates of the 4 centrifuge tubes respectively, shaking up, performing ultrasonic treatment for 10 minutes, taking out, continuing centrifugation, and repeating for several times until the pH value of the poured liquid after centrifugation is 5. Then 40ml of ethanol was added to each of 4 centrifuge tubes and sonicated for 1 hour, followed by centrifugation, and the lower layer precipitate was collected. 20ml of deionized water were added to each of the 4 collected centrifuge tubes, and the mixture was then dilutedAfter 1 hour of disruption in the cell disruptor, the supernatant, i.e., the desired MXene solution, was collected by centrifugation for 3 minutes.

(3)Fe₂O₃Preparation of/MXene film

Spin coating 20 μ L MXene liquid on the resulting Fe with a pipette gun₂O₃Drying the film at 60 ℃ to obtain the required Fe₂O₃a/MXene photocathode material. The MXene films had a thickness of about 1.3 μm.

Performance testing

(1) Sample characterization

Fe prepared in step (1) of example 3₂O₃Thin film and Fe finally prepared₂O₃/MXene photocathode (Fe)₂O₃a/MXene film) as an example.

FIG. 1 shows Fe prepared in step (1) of example 3₂O₃FIG. 3 is a surface scanning electron micrograph of Fe₂O₃The sectional scanning electron micrograph shows that Fe is indeed successfully grown on the FTO₂O₃A film.

FIG. 2 is Fe prepared in example₂O₃Surface scanning electron microscope image of/MXene film, FIG. 4 is Fe₂O₃Cross-sectional scanning electron micrographs of/MXene film, as seen in Fe₂O₃An MXene layer was spin coated on the film.

FIG. 5 shows Fe prepared in step (1) of example 3₂O₃The comparison of the X-ray diffraction pattern also proves that Fe is indeed successfully prepared₂O₃A film.

FIG. 6 is Fe prepared in example 3₂O₃X-ray diffraction pattern of/MXene film, proving that Fe is prepared really₂O₃a/MXene film.

The samples of the remaining examples were also tested to obtain similar scanning electron micrographs and X-ray diffraction patterns, indicating Fe₂O₃Film and Fe₂O₃Successful preparation of the/MXene films.

(2) Performance testing

For each implementationExamples of the provided Fe₂O₃Photoelectrochemical decomposition of water by photocathode of/MXene film as working electrode for hydrogen production test, and Fe prepared in step (1) of example 3₂O₃Controls were performed as working electrodes.

The test procedure was as follows: in a reaction container, sodium hydroxide (1mol/L) is used as an electrolyte, AgCl is used as a reference electrode, Pt is used as a counter electrode to form an electrolytic cell system, a proper amount (for example, 100mL) of electrolyte is added, a circuit is connected, a 300W xenon lamp is used for irradiation, an electrochemical workstation is started, a computer is started to set parameters, and the test and the recording of the result show the performance.

FIG. 7 is Fe₂O₃And Fe as provided in the examples₂O₃Graph comparing photocurrent density-bias curve of/MXene thin film, wherein, FIG. 7a is Fe₂O₃Fig. 7b is the photoelectrochemical property test of example 1, fig. 7c is the photoelectrochemical property test of example 2, fig. 7d is the photoelectrochemical property test of example 3, and fig. 7e is the photoelectrochemical property test of example 4. As can be seen from the figure, the examples provide Fe₂O₃The photoelectrochemical performance of the/MXene film is obviously better than that of Fe₂O₃The film performance is better.

FIG. 8 is Fe₂O₃And Fe as provided in the examples₂O₃The photocurrent density versus time curves of the/MXene films were compared to investigate robustness. Wherein, FIG. 8a is Fe₂O₃Fig. 8b is a photocurrent density-time curve of example 1, fig. 8c is a photocurrent density-time curve of example 2, fig. 8d is a photocurrent density-time curve of example 3, and fig. 8e is a photocurrent density-time curve of example 4. As can be seen from the figure, the examples provide Fe₂O₃The photocurrent density of the/MXene film changes regularly with time and is stabilized at a higher photoelectricity density level, and the photoelectrochemistry stability of the film is more stable than that of Fe₂O₃The stability of the film is better.

Fe provided for the examples₂O₃Photocathode feeding of/MXene filmUV-VIS absorption test was performed while Fe prepared in example 3, step (1)₂O₃Controls were performed.

FIG. 9 is Fe₂O₃And Fe as provided in example 3₂O₃UV-vis absorption spectrum of/MXene films. As can be seen from the figure, the light cathode provided in example 3 has a certain response to visible light, and the other examples also have similar response performance to example 3.

As is clear from the above, the Fe provided by the present invention₂O₃the/MXene photocathode has the advantages of high stability, visible light response and the like, and has high photocurrent density, high transport efficiency of photon-generated carriers and high efficiency of photolysis of water to produce hydrogen; and the raw materials are cheap and easy to obtain.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (10)

1. Fe₂O₃the/MXene photocathode is characterized by comprising a substrate and Fe sequentially loaded on the substrate₂O₃Films and Mxene films; the thickness of the Mxene film is 0.9-1.3 μm.

2. Fe according to claim 1₂O₃the/MXene photocathode is characterized in that the Fe₂O₃The film has a thickness of 0.8 to 1.5 μm.

3. Fe according to claim 1₂O₃the/MXene photocathode is characterized in that the substrate is FTO conductive glass or ITO conductive glass.

4. Fe as set forth in any one of claims 1 to 3₂O₃A preparation method of an MXene photocathode,the method is characterized by comprising the following steps:

s1: deposition of Fe on a substrate by hydrothermal reaction₂O₃Precursor, then heat treatment to obtain Fe₂O₃A film;

s2: in Fe₂O₃Coating Mxene solution on the film, and drying to obtain the Fe₂O₃a/MXene photocathode.

5. The method according to claim 4, wherein the process of S1 is as follows:

s11: adding nitrate into the solution containing the ferric salt to obtain a mixed solution; the pH value of the solution containing the trivalent ferric salt is 6-8;

s12: placing the substrate in the mixed solution, carrying out hydrothermal reaction, taking out the substrate, and drying;

s13: and annealing the substrate obtained in the step S12 at 500-550 ℃, and sintering at a high temperature of 700-800 ℃ to obtain the high-temperature-resistant high-performance ceramic.

6. The method according to claim 5, wherein the ferric iron source in S12 is ferric chloride.

7. The preparation method according to claim 5, wherein the hydrothermal reaction in S12 is carried out at 100-120 ℃ for 6-8 h.

8. The method according to claim 5, wherein the annealing in S12 is performed for 2-5 h; the high-temperature sintering time is 2-3 h.

9. The method of claim 4, wherein the Mxene solution in S2 is prepared by the following steps:

s21: for MAX-Ti₃AlC₂Etching, centrifuging and taking precipitate;

s22: dissolving the precipitate in organic solution, performing ultrasonic treatment, and centrifuging to obtain precipitate;

s23: adding water into the precipitate, crushing, centrifuging and taking supernatant to obtain the Mxene solution.

10. Fe as set forth in any one of claims 1 to 3₂O₃The application of the/MXene photocathode in the field of photoelectrochemistry.

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