Graphite phase carbon nitride supported platinum-iron bimetallic single-atom composite material, and preparation method and application thereof

Abstract

This invention relates to the field of photocatalysis technology, specifically to a graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material, its preparation method, and its application. This invention provides a graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material, which uses graphitic carbon nitride nanosheets as a carrier and loads platinum-iron bimetallic single atoms. By comparing ultraviolet-visible absorption spectra, it was found that the graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material provided by this invention enhances light absorption capacity, improving the utilization rate of sunlight. Furthermore, the platinum-iron bimetallic single atoms synergistically enhance the separation of photogenerated electrons and holes from the graphitic carbon nitride nanosheets, which is beneficial for carrier transport and enhances photocatalytic performance.

Description

Technical Field

[0001] This invention relates to the field of photocatalysis technology, specifically to a graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Currently, the efficiency of photocatalytic hydrogen production is mainly limited by the lack of efficient catalysts. In recent years, graphitic carbon nitride (g-C3N4), as a novel non-metallic semiconductor material, has a series of advantages, including abundant sources, simple synthesis processes, low cost, and non-toxicity. Furthermore, due to its relatively small band gap and stable optical properties, it has wide applications in photochemical water hydrogen production. However, graphitic carbon nitride is a wide-bandgap semiconductor with a band gap of approximately 2.7 eV. It can only be excited by ultraviolet light with wavelengths below 460 nm and a small amount of visible light, causing valence band electrons to jump and form electron-hole pairs. In the solar spectrum, ultraviolet light accounts for only about 5%, while visible light accounts for as much as 48%. However, graphitic carbon nitride does not respond to most visible light, resulting in relatively low light absorption intensity. Moreover, under sunlight irradiation, the electron-hole pairs generated within the material readily recombine in the form of light or heat, a problem that severely limits its performance in practical photocatalytic applications.

[0004] To improve the catalytic performance of g-C3N4 photocatalysts, modifications such as element doping, vacancy engineering, and morphology control are commonly employed. However, the modified g-C3N4 photocatalysts still suffer from problems such as narrow spectral response and low catalytic efficiency, which limits their application in photocatalytic hydrogen production. Summary of the Invention

[0005] To overcome the above problems, this invention provides a graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material, its preparation method, and its application.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material, which uses graphitic carbon nitride nanosheets as a carrier and loads platinum-iron bimetallic single atoms.

[0007] In one or more embodiments, the mass ratio of iron single atoms, graphitic carbon nitride nanosheets and platinum single atoms is (1~5):100:1, preferably 1.5:100:1.

[0008] A second aspect of the present invention provides a method for preparing the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material described in the first aspect, comprising the following steps: The iron source was dissolved in an aqueous solution of graphitic carbon nitride nanosheets, and the solid was collected by centrifugation to obtain the first intermediate. The first intermediate was heat-treated under oxygen-free conditions to obtain the second intermediate; The second intermediate, sacrificial agent, platinum source and water are mixed to obtain a suspension; A graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material was obtained by loading platinum single atoms onto the surface of a second intermediate using a photochemical reduction method.

[0009] In one or more embodiments, the concentration of graphitic carbon nitride nanosheets in the aqueous solution is (10~15) g / L, preferably 12.5 g / L.

[0010] In one or more embodiments, the iron source includes one or more of ferric chloride, ferric nitrate, or ferric acetate.

[0011] In one or more embodiments, the mass ratio of iron element in the iron source to graphite-phase carbon nitride nanosheets is (1~5):100.

[0012] In one or more embodiments, the oxygen-free conditions include nitrogen or rare gases.

[0013] In one or more embodiments, the heat treatment temperature is 400~500℃ and the heat treatment time is 3.5~5 h.

[0014] In one or more embodiments, the sacrificial agent is triethanolamine.

[0015] In one or more embodiments, the platinum source includes one or more of platinum acetylacetonate, chloroplatinic acid, potassium chloroplatinate, potassium chloroplatinate, platinum nitrate, or ammonium chloroplatinate, preferably chloroplatinic acid.

[0016] In one or more embodiments, the mass ratio of platinum element in the platinum source to graphitic carbon nitride nanosheets is 1:100.

[0017] A third aspect of the present invention provides the application of the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material described in the first aspect or the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material prepared by the preparation method described in the second aspect as a photocatalyst.

[0018] In one or more embodiments, the application includes: catalytic water splitting for hydrogen production under visible light.

[0019] A fourth aspect of the present invention provides a method for photocatalytic water splitting to produce hydrogen, comprising the following steps: A suspension is obtained by mixing the photocatalyst, the sacrificial agent, and water. A light source is applied to the mixture to perform photocatalytic hydrolysis and produce hydrogen gas; The photocatalyst is the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material described in the first aspect or the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material prepared by the preparation method described in the second aspect.

[0020] In one or more embodiments, the sacrificial agent is triethanolamine (TEOA).

[0021] The beneficial effects of this invention are as follows: This invention provides a graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material, which uses graphitic carbon nitride nanosheets as a carrier and loads platinum-iron bimetallic single atoms. By comparing the ultraviolet-visible absorption spectra, it was found that the graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material provided by this invention has enhanced light absorption capacity, improving the utilization rate of sunlight. Furthermore, the platinum-iron bimetallic single atoms synergistically enhance the separation of photogenerated electrons and holes in the graphitic carbon nitride nanosheets, which is beneficial for carrier transport and enhances photocatalytic performance. The optimal hydrogen production rate of the graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material of this invention can reach 5819 μmol·g⁻¹. -1 ·h -1 . Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 A graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material (Pt1Fe) 1.5 Scanning electron microscope image of / g-C3N4); Figure 2 A graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material (Pt1Fe) 1.5 Aberration-corrected electron micrograph of / g-C3N4); Figure 3 The effects of photocatalytic water splitting for hydrogen production on the graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite materials prepared in Examples 1-4 are shown; wherein, (a) is a schematic diagram of the photocatalytic water splitting for hydrogen production activity, and (b) is a schematic diagram of the photocatalytic water splitting for hydrogen production rate. Figure 4 The graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite material (Pt1Fe) prepared in Example 21.5 / g-C3N4) and the photocatalytic water splitting hydrogen production effect of the materials prepared in Comparative Examples 1 to 3; wherein, (a) is a schematic diagram of the photocatalytic water splitting hydrogen production activity, and (b) is a schematic diagram of the photocatalytic water splitting hydrogen production rate. Figure 5 The graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite material (Pt1Fe) prepared in Example 2 1.5 Comparison of UV-Vis absorption intensity of the materials prepared in Comparative Examples 1-3 ( / g-C3N4) and Comparative Examples 1-3. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] In recent years, graphitic carbon nitride (g-C3N4), as a novel non-metallic semiconductor material, has a series of advantages such as abundant sources, simple synthesis processes, low prices, and non-toxicity and pollution-free properties. Moreover, due to its relatively small band gap and stable optical properties, it has been widely used in the field of photochemical water production. However, pure, unmodified g-C3N4 photocatalysts have a narrow photoresponse range in photocatalytic reactions and a high recombination rate of photogenerated carriers. In particular, bulk g-C3N4 also suffers from many defects such as small specific surface area and low electrical conductivity, resulting in its photocatalytic water splitting efficiency being far lower than the industrial standard.

[0027] Two-dimensional graphitic carbon nitride nanosheets facilitate mass transfer between reactants and products, enhance reaction kinetics, and promote the activity of hollow photocatalysts. The layered structure has a high specific surface area and a short charge transport distance, which are all advantages that help improve the photocatalytic performance of graphitic carbon nitride. However, two-dimensional graphitic carbon nitride nanosheets exhibit low UV-Vis light absorption capacity and low photocatalytic water splitting to produce hydrogen. This is due to the limited UV-Vis light absorption capacity and rapid electron-hole recombination.

[0028] This invention provides a graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material, which uses graphitic carbon nitride nanosheets as a carrier to load platinum-iron bimetallic single atoms. By comparing the ultraviolet-visible absorption spectra, it was found that the light absorption capacity of the graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material provided by this invention is enhanced. This is because the platinum-iron bimetallic single atoms introduce impurity energy levels into the carbon nitride, generating a localized light field enhancement effect and contributing additional transition modes, which together broaden the wavelength range of light absorption and increase the absorption intensity. This allows the material to capture more wavelengths of solar energy, thereby improving its absorption capacity. This improves the utilization rate of sunlight. In addition, the synergistic effect of platinum-iron bimetallic single atoms enhances the separation of photogenerated electrons and holes in graphitic carbon nitride nanosheets. When semiconductor graphitic carbon nitride nanosheets are excited by light, they generate photogenerated electrons and holes. At this time, the loaded platinum-iron bimetallic single atoms act as electron traps, and the added sacrificial reagent triethanolamine acts as a hole trap. The two work together to separate photogenerated electrons and holes in space. At the same time, the single-atom coordination structure accelerates the migration of charge carriers from the bulk phase to the surface, allowing more electron-hole pairs to migrate to the surface and participate in the surface redox reaction, which is beneficial to the transport of charge carriers and enhances the photocatalytic performance.

[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0030] Example 1 Preparation of graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material (Pt1Fe1 / g-C3N4): (1) Wrap 10 g of dry urea in aluminum foil, place it in a crucible, heat it to 550°C at a heating rate of 5°C / min, keep it at this temperature for 2 h, cool it to room temperature with the furnace, and grind it thoroughly to prepare two-dimensional graphitic carbon nitride nanosheets.

[0031] (2) 0.5 g of graphitic carbon nitride nanosheets were dispersed in 40 mL of deionized water and sonicated for 30 min to obtain an aqueous solution of graphitic carbon nitride nanosheets; then 24.1 mg of ferric chloride hexahydrate was dissolved in the aqueous solution of graphitic carbon nitride nanosheets, stirred for 3 h and centrifuged to collect the solid, washed with deionized water and dried at 80 °C overnight to obtain the first intermediate.

[0032] (3) The first intermediate is placed in a muffle furnace and heated to 450°C at a heating rate of 5°C / min under a nitrogen atmosphere, and held at this temperature for 4 h to obtain the second intermediate.

[0033] (4) The second intermediate was added to a mixed solution of 10 mL triethanolamine and 40 mL deionized water and sonicated for 30 min; then 27 μL of 10 g / L chloroplatinic acid hexahydrate aqueous solution was added and stirred until homogeneous to obtain a suspension.

[0034] (4) The entire suspension was irradiated under a 300 W xenon lamp for 1 h and then centrifuged. The solid was collected, washed with deionized water, and dried overnight at 80 °C to obtain a graphite phase carbon nitride supported platinum iron bimetallic single-atom composite material (Pt1Fe1 / g-C3N4).

[0035] Example 2 Graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material (Pt1Fe) 1.5 Preparation of / g-C3N4): (1) Wrap 10 g of dry urea in aluminum foil, place it in a crucible, heat it to 550°C at a heating rate of 5°C / min, keep it at this temperature for 2 h, cool it to room temperature with the furnace, and grind it thoroughly to prepare two-dimensional graphitic carbon nitride nanosheets.

[0036] (2) 0.5 g of graphitic carbon nitride nanosheets were dispersed in 40 mL of deionized water and sonicated for 30 min to obtain an aqueous solution of graphitic carbon nitride nanosheets; then 36.3 mg of ferric chloride hexahydrate was dissolved in the aqueous solution of graphitic carbon nitride nanosheets, stirred for 3 h and centrifuged to collect the solid, washed with deionized water and dried at 80 °C overnight to obtain the first intermediate.

[0037] (3) The first intermediate is placed in a muffle furnace and heated to 450°C at a heating rate of 5°C / min under a nitrogen atmosphere, and held at this temperature for 4 h to obtain the second intermediate.

[0038] (4) The second intermediate was added to a mixed solution of 10 mL triethanolamine and 40 mL deionized water and sonicated for 30 min; then 27 μL of 10 g / L chloroplatinic acid hexahydrate aqueous solution was added and stirred until homogeneous to obtain a suspension.

[0039] (4) The entire suspension was irradiated under a 300 W xenon lamp for 1 h, centrifuged, the solid was collected, washed with deionized water, and dried overnight at 80 °C to obtain a graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite material (Pt1Fe). 1.5 / g-C3N4).

[0040] Example 3 Preparation of graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material (Pt1Fe3 / g-C3N4): (1) Wrap 10 g of dry urea in aluminum foil, place it in a crucible, heat it to 550°C at a heating rate of 5°C / min, keep it at this temperature for 2 h, cool it to room temperature with the furnace, and grind it thoroughly to prepare two-dimensional graphitic carbon nitride nanosheets.

[0041] (2) 0.5 g of graphitic carbon nitride nanosheets were dispersed in 40 mL of deionized water and sonicated for 30 min to obtain an aqueous solution of graphitic carbon nitride nanosheets; then 72.6 mg of ferric chloride hexahydrate was dissolved in the aqueous solution of graphitic carbon nitride nanosheets, stirred for 3 h and centrifuged to collect the solid, washed with deionized water and dried at 80 °C overnight to obtain the first intermediate.

[0042] (3) The first intermediate is placed in a muffle furnace and heated to 450°C at a heating rate of 5°C / min under a nitrogen atmosphere, and held at this temperature for 4 h to obtain the second intermediate.

[0043] (4) The second intermediate was added to a mixed solution of 10 mL triethanolamine and 40 mL deionized water and sonicated for 30 min; then 27 μL of 10 g / L chloroplatinic acid hexahydrate aqueous solution was added and stirred until homogeneous to obtain a suspension.

[0044] (4) The entire suspension was irradiated under a 300 W xenon lamp for 1 h and then centrifuged. The solid was collected, washed with deionized water, and dried at 80 °C overnight to obtain a graphite phase carbon nitride supported platinum iron bimetallic single-atom composite material (Pt1Fe3 / g-C3N4).

[0045] Example 4 Preparation of graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material (Pt1Fe5 / g-C3N4): (1) Wrap 10 g of dry urea in aluminum foil, place it in a crucible, heat it to 550°C at a heating rate of 5°C / min, keep it at this temperature for 2 h, cool it to room temperature with the furnace, and grind it thoroughly to prepare two-dimensional graphitic carbon nitride nanosheets.

[0046] (2) 0.5 g of graphitic carbon nitride nanosheets were dispersed in 40 mL of deionized water and sonicated for 30 min to obtain an aqueous solution of graphitic carbon nitride nanosheets; then 120.5 mg of ferric chloride hexahydrate was dissolved in the aqueous solution of graphitic carbon nitride nanosheets, stirred for 3 h and centrifuged to collect the solid, washed with deionized water and dried at 80 °C overnight to obtain the first intermediate.

[0047] (3) The first intermediate is placed in a muffle furnace and heated to 450°C at a heating rate of 5°C / min under a nitrogen atmosphere, and held at this temperature for 4 h to obtain the second intermediate.

[0048] (4) The second intermediate was added to a mixed solution of 10 mL triethanolamine and 40 mL deionized water and sonicated for 30 min; then 27 μL of 10 g / L chloroplatinic acid hexahydrate aqueous solution was added and stirred until homogeneous to obtain a suspension.

[0049] (4) The entire suspension was irradiated under a 300 W xenon lamp for 1 h and then centrifuged. The solid was collected, washed with deionized water, and dried overnight at 80 °C to obtain a graphite phase carbon nitride supported platinum iron bimetallic single-atom composite material (Pt1Fe5 / g-C3N4).

[0050] Comparative Example 1 Preparation of two-dimensional graphitic carbon nitride nanosheets: 10 g of dry urea was wrapped in aluminum foil, placed in a crucible, heated to 550 °C at a heating rate of 5 °C / min, and held at this temperature for 2 h. The mixture was then cooled to room temperature in the furnace and thoroughly ground to prepare two-dimensional graphitic carbon nitride nanosheets.

[0051] Comparative Example 2 Preparation of graphitic carbon nitride-supported iron single-atom composite materials: (1) Wrap 10 g of dry urea in aluminum foil, place it in a crucible, heat it to 550°C at a heating rate of 5°C / min, keep it at this temperature for 2 h, cool it to room temperature with the furnace, and grind it thoroughly to prepare two-dimensional graphitic carbon nitride nanosheets.

[0052] (2) 0.5 g of graphitic carbon nitride nanosheets were dispersed in 40 mL of deionized water and sonicated for 30 min to obtain an aqueous solution of graphitic carbon nitride nanosheets; then 36.3 mg of ferric chloride hexahydrate was dissolved in the aqueous solution of graphitic carbon nitride nanosheets, stirred for 3 h and centrifuged to collect the solid, washed with deionized water and dried at 80 °C overnight to obtain the first intermediate.

[0053] (3) The first intermediate was placed in a muffle furnace and heated to 450°C at a heating rate of 5°C / min under a nitrogen atmosphere. The mixture was then held at this temperature for 4 h to obtain a graphite phase carbon nitride supported iron single-atom composite material.

[0054] Comparative Example 3 Preparation of graphitic carbon nitride-supported platinum single-atom composite materials: (1) Wrap 10 g of dry urea in aluminum foil, place it in a crucible, heat it to 550°C at a heating rate of 5°C / min, keep it at this temperature for 2 h, cool it to room temperature with the furnace, and grind it thoroughly to prepare two-dimensional graphitic carbon nitride nanosheets.

[0055] (2) 0.5 g of graphitic carbon nitride nanosheets were added to a mixed solution of 10 mL of triethanolamine and 40 mL of deionized water and sonicated for 30 min. Then 27 μL of chloroplatinic acid hexahydrate aqueous solution with a concentration of 10 g / L was added and stirred evenly to obtain a suspension.

[0056] (4) The entire suspension was irradiated under a 300 W xenon lamp for 1 h and then centrifuged. The solid was collected, washed with deionized water, and dried overnight at 80 °C to obtain a graphite phase carbon nitride supported platinum single-atom composite material.

[0057] Figure 1 A graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material (Pt1Fe) 1.5 The scanning electron microscope image of / g-C3N4 shows that the graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite material (Pt1Fe) can be observed. 1.5 / g-C3N4) has a plate-like structure.

[0058] Figure 2 A graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material (Pt1Fe) 1.5 The image shows a spherical aberration electron microscope image of / g-C3N4, where the blue circles mark the observed platinum-iron bimetallic single-atom sites, and the red circles mark the observed platinum or iron single-atom sites.

[0059] Example 5 Photocatalytic water splitting for hydrogen production performance test: (1) Weigh 10 mg of catalyst sample powder and transfer it to a clean beaker.

[0060] (2) Measure 40 mL of deionized water and 10 mL of triethanolamine and transfer them to a beaker containing the sample to be tested.

[0061] (3) Stir the mixed solution in the beaker and sonicate it to disperse it evenly, and then transfer it to the reactor.

[0062] (4) Connect the reactor containing the mixed solution to the GC-7290 gas chromatography system to determine the performance of photocatalytic water splitting to produce hydrogen.

[0063] Figure 3 To demonstrate the photocatalytic water splitting and hydrogen production effects of the graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite materials prepared in Examples 1-4 and the catalyst materials prepared in Comparative Examples 1 and 3, the Pt1Fe in this invention... 1.5 The optimal hydrogen production rate of the / g-C3N4 graphitic carbon nitride supported platinum-iron bimetallic single-atom composite material reached 5819 μmol·g. -1 ·h -1At this ratio, the synergistic catalytic effect of platinum-iron bimetallic single atoms optimizes the hydrogen production performance of the composite material.

[0064] Figure 4 The graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite material (Pt1Fe) prepared in Example 2 1.5 / g-C3N4) and the photocatalytic water splitting to hydrogen production effect of the materials prepared in Comparative Examples 1-3, Pt1Fe 1.5 The optimal hydrogen production rate of the / g-C3N4 graphitic carbon nitride supported platinum-iron bimetallic single-atom composite material reached 5819 μmol·g. -1 ·h -1 At this ratio, the synergistic catalytic effect of platinum-iron bimetallic single atoms makes the hydrogen production performance of the composite material superior to that of the samples in Comparative Examples 1-3. This indicates that, compared to platinum or iron atoms existing alone, the synergistic effect of platinum-iron bimetallic atoms is more effective in improving the hydrogen production performance of carbon nitride prepared in Comparative Example 1.

[0065] Figure 5 The graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite material (Pt1Fe) prepared in Example 2 1.5 A comparison of the UV-Vis absorption intensity of Pt1Fe (g-C3N4) and the materials prepared in Comparative Examples 1-3, and Pt1Fe 1.5 The / g-C3N4 composite material exhibits the strongest ultraviolet-visible light absorption intensity, which is consistent with its optimal photocatalytic water splitting for hydrogen production.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material, characterized in that, It uses graphitic carbon nitride nanosheets as a carrier to load platinum-iron bimetallic single atoms.

2. The graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite material as described in claim 1, characterized in that, The mass ratio of iron single atoms, graphitic carbon nitride nanosheets and platinum single atoms is (1~5):100:1, preferably 1.5:100:

1.

3. The method for preparing the graphite-phase carbon nitride-supported platinum-iron bimetallic single-atom composite material according to claim 1 or 2, characterized in that, Includes the following steps: The iron source was dissolved in an aqueous solution of graphitic carbon nitride nanosheets, and the solid was collected by centrifugation to obtain the first intermediate. The first intermediate was heat-treated under oxygen-free conditions to obtain the second intermediate; The second intermediate, sacrificial agent, platinum source and water are mixed to obtain a suspension; A graphitic carbon nitride-supported platinum-iron bimetallic single-atom composite material was obtained by loading platinum single atoms onto the surface of a second intermediate using a photochemical reduction method.

4. The preparation method according to claim 3, characterized in that, In the aqueous solution of graphitic carbon nitride nanosheets, the concentration of graphitic carbon nitride nanosheets is (10~15) g / L, preferably 12.5 g / L; Alternatively, the iron source may include one or more of ferric chloride, ferric nitrate, or ferric acetate; Alternatively, the mass ratio of iron in the iron source to graphite-phase carbon nitride nanosheets is (1~5):

100.

5. The preparation method according to claim 3, characterized in that, The heat treatment temperature is 400~500℃, and the heat treatment time is 3.5~5 h.

6. The preparation method according to claim 3, characterized in that, The sacrificial agent is triethanolamine.

7. The preparation method according to claim 3, characterized in that, The platinum source includes one or more of platinum acetylacetonate, chloroplatinic acid, potassium chloroplatinate, potassium chloroplatinate, platinum nitrate, or ammonium chloroplatinate, preferably chloroplatinic acid; Alternatively, the mass ratio of platinum element in the platinum source to graphitic carbon nitride nanosheets is 1:

100.

8. The application of the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material according to claim 1 or 2, or the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material prepared by any one of claims 3 to 7, as a photocatalyst.

9. The application as described in claim 8, characterized in that, The applications include: catalytic water splitting for hydrogen production under visible light.

10. A method for photocatalytic water splitting to produce hydrogen, characterized in that, Includes the following steps: A suspension is obtained by mixing the photocatalyst, the sacrificial agent, and water. A light source is applied to the mixture to perform photocatalytic hydrolysis and produce hydrogen gas; The photocatalyst is the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material according to claim 1 or 2, or the graphite-phase carbon nitride supported platinum-iron bimetallic single-atom composite material prepared by the preparation method according to any one of claims 3 to 7.

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