A bimetallic framework modified carbon nitride microsphere catalyst, a preparation method therefor, and an application thereof

Abstract

This invention provides a bimetallic framework-modified carbon nitride microsphere catalyst, its preparation method, and its application, belonging to the field of photocatalytic materials technology. First, g-C3N4 is mixed with concentrated nitric acid and concentrated sulfuric acid for oxidation treatment to obtain oxidized graphitic carbon nitride. Then, the oxidized graphitic carbon nitride, a mixed salt solution, and 1,3,5-benzenetricarboxylic acid are mixed and subjected to a hydrothermal reaction to obtain the bimetallic framework-modified carbon nitride microsphere catalyst. This invention effectively promotes the separation and transport of photogenerated electron-hole pairs through the bimetallic synergistic effect and the unique double S-type heterojunction structure, resulting in high hydrogen production efficiency. Under visible light irradiation, its photocatalytic hydrogen evolution rate can reach up to 14.79 mmol·g⁻¹. ‑1 ·h ‑1 It is 2.86 times that of the single-metal composite material CNO@CuMOF and 47 times that of pure CNO, significantly improving the photocatalytic hydrogen production activity.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, and in particular to a bimetallic framework modified carbon nitride microsphere catalyst, its preparation method, and its application. Background Technology

[0002] With the increasing severity of the global energy crisis and environmental problems, the development of clean and renewable hydrogen energy has become a research hotspot in the energy field. Photocatalytic water splitting for hydrogen production, which can directly convert solar energy into hydrogen energy, has advantages such as zero carbon emissions and strong sustainability, and is considered one of the most promising methods for green hydrogen production.

[0003] Graphitic carbon nitride (g-C3N4), as a non-metallic polymer semiconductor photocatalyst, has attracted widespread attention in the field of photocatalytic hydrogen production due to its suitable band structure, good chemical stability, low cost, and ease of preparation. However, pure g-C3N4 suffers from drawbacks such as limited specific surface area, rapid recombination rate of photogenerated electron-hole pairs, and narrow visible light absorption range, resulting in low photocatalytic hydrogen production activity. Carbon nitride oxide (CNO), prepared by strong acid etching modification, can effectively increase specific surface area and improve charge separation. When combined with single-metal CuMOF, it can further broaden the light absorption range and improve carrier migration efficiency. However, the single-metal MOF system still suffers from drawbacks such as single active sites, weak interfacial bonding, and insufficient long-term stability, making it difficult to meet the requirements of efficient, stable, and multifunctional photocatalysts.

[0004] Bimetallic framework compounds can leverage the synergistic electronic effects between two metals to optimize band structure, increase the number of active sites, and enhance interfacial charge transfer, while simultaneously improving material structural stability and photoresponse capability. This represents an effective strategy to overcome the bottlenecks of monometallic systems. However, existing methods for combining bimetallic MOFs with carbon nitride often involve physical mixing or disordered loading, which can lead to problems such as masking of active centers, weak heterojunction interfacial contact, and low charge transport efficiency. Therefore, developing a bimetallic framework-modified carbon nitride microsphere catalyst with strong interfacial bonding, high charge separation efficiency, and dual functions of hydrogen production and degradation, along with its preparation method, has significant practical application value. Summary of the Invention

[0005] The purpose of this invention is to provide a bimetallic framework modified carbon nitride microsphere catalyst, its preparation method and application, to solve the problems in the prior art where the physical composite of bimetallic MOF and carbon nitride leads to the masking of active centers, poor contact at the heterojunction interface and low charge transport efficiency.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing a bimetallic framework modified carbon nitride microsphere catalyst, comprising the following steps: (1) Mix g-C3N4 with concentrated nitric acid and concentrated sulfuric acid and perform oxidation treatment to obtain oxidized graphitic carbon nitride; (2) Oxidized graphitic carbon nitride, mixed salt solution and 1,3,5-benzenetricarboxylic acid were mixed and subjected to hydrothermal reaction to obtain bimetallic framework modified carbon nitride microsphere catalyst.

[0007] Preferably, in step (1), the mass-to-volume ratio of g-C3N4 to concentrated nitric acid and concentrated sulfuric acid is 4~6g:60~70mL:30~35mL.

[0008] Preferably, in step (1), the oxidation treatment is carried out at room temperature for 6 to 14 hours.

[0009] Preferably, in step (2), the salts in the mixed salt solution are copper salts and cobalt salts: the molar ratio of copper ions to cobalt ions in the mixed salt solution is 1:0.5~1.25.

[0010] Preferably, the mass ratio of the oxidized modified graphitic carbon nitride to copper salt and cobalt salt is 0.05~0.2:0.2~0.3:0.2~0.4.

[0011] Preferably, the mass ratio of the copper salt to 1,3,5-benzenetricarboxylic acid is 0.2~0.3:0.4~0.5.

[0012] Preferably, in step (2), the temperature of the hydrothermal reaction is 100~140℃ and the time of the hydrothermal reaction is 10~14h.

[0013] The present invention also provides a bimetallic framework modified carbon nitride microsphere catalyst prepared by the above-described method.

[0014] This invention also provides an application of the bimetallic framework modified carbon nitride microsphere catalyst described above in catalytic water splitting for hydrogen production. The bimetallic framework modified carbon nitride microsphere catalyst is used as a photocatalyst, eosin Y is used as a photosensitizer, and triethanolamine is used as an electron donor to construct an aqueous photocatalytic reaction system.

[0015] Preferably, the specific steps for hydrogen production by hydrolysis are as follows: dispersing bimetallic framework modified carbon nitride microsphere catalyst, eosin Y and triethanolamine in water, adjusting the pH value and then carrying out the reaction.

[0016] The beneficial effects of this invention are: This invention introduces abundant oxygen-containing functional groups on the surface of carbon nitride through oxidation modification, and realizes the directional growth of bimetallic CuCoMOF on the CNO surface using an in-situ synthesis method, forming a hierarchical porous microsphere structure with strong interfacial bonding. This structure combines the layered folds of CNO, the octahedral features of CuMOF, and the hollow microsphere features of CoMOF. CNO is embedded inside the metal framework, the interfacial bonding is tight, and the elemental distribution is uniform, effectively solving the problems of phase separation and masking of active sites caused by traditional physical mixing.

[0017] The bimetallic framework-modified carbon nitride microsphere catalyst of this invention benefits from the bimetallic synergistic effect and unique double S-shaped heterojunction structure, effectively promoting the separation and transport of photogenerated electron-hole pairs, resulting in high hydrogen production efficiency. Under visible light irradiation, its photocatalytic hydrogen evolution rate can reach up to 14.79 mmol·g⁻¹. -1 ·h -1 It is 2.86 times that of the single-metal composite material CNO@CuMOF and 47 times that of pure CNO, showing a significantly improved photocatalytic hydrogen production activity.

[0018] The bimetallic framework-modified carbon nitride microsphere catalyst of this invention features a wide light absorption range and high carrier separation efficiency. The introduction of bimetal reduces the band gap from 2.98 eV for CNO to 2.76 eV, significantly broadening the visible light absorption range. Photoelectrochemical tests using PL, EIS, and LSV demonstrate that the bimetallic framework-modified carbon nitride microsphere catalyst exhibits a significantly reduced photogenerated carrier recombination rate, decreased charge transfer resistance, and a substantial increase in photocurrent density, providing an excellent kinetic basis for highly efficient photocatalytic reactions.

[0019] The bimetallic framework modified carbon nitride microsphere catalyst prepared in this invention has dual functions, combining hydrogen production and degradation performance. It not only has excellent photocatalytic hydrogen production performance, but also achieves degradation rates of 98% (12 min) and 86% (60 min) for Rhodamine B (RhB) and tetracycline (TC) under visible light irradiation, respectively. The degradation rate constants are 2.89 times and 1.92 times that of the single metal composite material, respectively, realizing the dual functions of photocatalytic hydrogen production and pollutant degradation.

[0020] The bimetallic framework-modified carbon nitride microsphere catalyst prepared in this invention exhibits good stability and is recyclable. This is because the bimetallic framework is firmly bonded to the CNO substrate through chemical bonds, resulting in high structural stability. After the photocatalytic reaction, it can be recycled after simple washing and drying. After five cycles, the hydrogen production activity remains above 90%, indicating that the crystal structure and chemical functional groups of the catalyst do not change significantly, demonstrating promising application prospects.

[0021] This invention reveals for the first time that bimetallic framework-modified carbon nitride microsphere catalysts follow a double S-type charge transfer mechanism, with a built-in electric field driving the recombination of relatively useless charge carriers, while retaining high-reducing-capacity conduction band electrons and high-oxidizing-capacity valence band holes, thus simultaneously achieving efficient photocatalytic hydrogen production and pollutant degradation, providing a new theoretical paradigm for designing stable and efficient carbon nitride-based composite photocatalysts. Attached Figure Description

[0022] Figure 1 The image shows a scanning electron microscope (SEM) image of CNO@CuCoMOF-1 prepared in Example 1. Detailed Implementation

[0023] This invention provides a method for preparing a bimetallic framework modified carbon nitride microsphere catalyst, comprising the following steps: (1) Mix g-C3N4 with concentrated nitric acid and concentrated sulfuric acid and perform oxidation treatment to obtain oxidized graphitic carbon nitride; (2) Oxidized graphitic carbon nitride, mixed salt solution and 1,3,5-benzenetricarboxylic acid were mixed and subjected to hydrothermal reaction to obtain bimetallic framework modified carbon nitride microsphere catalyst.

[0024] In this invention, in step (1), the mass-to-volume ratio of g-C3N4 to concentrated nitric acid and concentrated sulfuric acid is 4~6g:60~70mL:30~35mL, preferably 5g:62~68mL:32~34mL, and more preferably 5g:64~66.67mL:33.33mL.

[0025] In this invention, in step (1), the oxidation treatment is carried out at room temperature for 6 to 14 hours, preferably 8 to 13 hours, and more preferably 10 to 12 hours.

[0026] In this invention, the specific process of mixing the oxidized graphitic carbon nitride, the mixed salt solution, and 1,3,5-benzenetricarboxylic acid is as follows: mixing the oxidized graphitic carbon nitride and the mixed salt solution to obtain a dispersion; mixing the 1,3,5-benzenetricarboxylic acid and the solvent to obtain a 1,3,5-benzenetricarboxylic acid solution; and then mixing the 1,3,5-benzenetricarboxylic acid solution and the dispersion.

[0027] In this invention, in step (2), the salts in the mixed salt solution are copper salts and cobalt salts: the molar ratio of copper ions to cobalt ions in the mixed salt solution is 1:0.5~1.25, specifically 1:0.5, 1:0.75, 1:1, or 1:1.25.

[0028] In this invention, the mass ratio of the oxidized graphitic carbon nitride to copper salt and cobalt salt is 0.05~0.2:0.2~0.3:0.2~0.4, preferably 0.1~0.15:0.242~0.26:0.291~0.35.

[0029] In this invention, the mass ratio of the copper salt to 1,3,5-benzenetricarboxylic acid is 0.2~0.3:0.4~0.5, preferably 0.242~0.26:0.421~0.46.

[0030] In this invention, in step (2), the temperature of the hydrothermal reaction is 100~140℃, preferably 115~135℃, and more preferably 120~130℃; the time of the hydrothermal reaction is 10~14h, preferably 11~13h, and more preferably 12h.

[0031] The present invention also provides a bimetallic framework modified carbon nitride microsphere catalyst prepared by the above-described method.

[0032] This invention also provides an application of the bimetallic framework modified carbon nitride microsphere catalyst described above in catalytic water splitting for hydrogen production. The bimetallic framework modified carbon nitride microsphere catalyst is used as a photocatalyst, eosin Y is used as a photosensitizer, and triethanolamine is used as an electron donor to construct an aqueous photocatalytic reaction system.

[0033] In this invention, the specific steps for hydrogen production by hydrolysis are as follows: dispersing bimetallic framework modified carbon nitride microsphere catalyst, eosin Y and triethanolamine in water, adjusting the pH value and then carrying out the reaction.

[0034] In this invention, the volume ratio of triethanolamine to water is 1:20~24, preferably 1:21~24, and more preferably 1:22~24; the amount of bimetallic framework modified carbon nitride microsphere catalyst added is 0.005~0.02g / 50mL, preferably 0.008~0.015g / 50mL, and more preferably 0.01g / 50mL; the amount of eosin Y added is 0.005~0.01g / 50mL, preferably 0.006~0.009g / 50mL, and more preferably 0.0075~0.008g / 50mL.

[0035] In this invention, the adjusted pH value is 8-9; the reaction is carried out under vacuum conditions and irradiated with a visible light source; the reaction temperature is 5-10°C, preferably 6-8°C; and the reaction time is 4 hours.

[0036] In this invention, the wavelength of the visible light source is 420 nm.

[0037] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0038] The g-C3N4 used in the embodiments and comparative examples of this invention was prepared as follows: 1g of dicyandiamide and 5g of urea were placed in an oven and dried at 80°C for 12 hours. After drying, the mixture was ground evenly to obtain a mixture. The mixture was then poured into a crucible and placed in a tube furnace. The temperature was increased to 530°C at a rate of 2°C / min and held for 3 hours for calcination. After cooling, the mixture was ground to obtain a yellow g-C3N4 powder.

[0039] Example 1 5g of graphitic carbon nitride (g-C3N4) yellow powder was dispersed in 100mL of a mixed acid of concentrated nitric acid and concentrated sulfuric acid (volume ratio of concentrated nitric acid to concentrated sulfuric acid was 2:1). The mixture was stirred at room temperature for 12h. After the reaction was completed, the mixture was washed with a large amount of deionized water until neutral, filtered, dried under vacuum at 60℃ for 12h, and ground to obtain oxidized graphitic carbon nitride powder, denoted as CNO.

[0040] 0.1 g CNO was dispersed in 15 mL of a mixed solution of copper nitrate and cobalt nitrate (the mixed solution was composed of 0.242 g Cu(NO3)2·3H2O, 0.291 g Co(NO3)2·6H2O, and 15 mL deionized water, with a molar ratio of copper ions to cobalt ions of 1:1), and ultrasonically dispersed for 1.5 h to obtain a dispersion. 0.421 g H3BTC was weighed and dissolved in a mixed solution composed of 15 mL anhydrous ethanol and 15 mL DMF to obtain an H3BTC solution. The H3BTC solution was added to the above dispersion, stirred for 0.5 h, transferred to a 100 mL polytetrafluoroethylene-lined high-pressure reactor, and reacted at 120 °C for 12 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed 5 times each with anhydrous ethanol and deionized water, and finally vacuum dried at 60 °C for 24 h to obtain a bimetallic framework modified carbon nitride microsphere catalyst, which was a blue-purple solid powder, denoted as CNO@CuCoMOF-1.

[0041] The CNO@CuCoMOF-1 obtained above was ground to 150 mesh, dried at 60°C for 12 hours, and then placed in a desiccator for later use.

[0042] In a 100 mL photocatalytic reactor, 48 mL of deionized water and 2 mL of triethanolamine were added, followed by 0.01 g of pretreated CNO@CuCoMOF-1 and 0.0075 g of eosin Y. The mixture was ultrasonically dispersed for 25 min to form a uniform suspension. The pH of the suspension was adjusted to 9.0 with dilute sodium hydroxide solution. The reactor was then sealed, and a vacuum pump was turned on to evacuate the system for 10 min to maintain the vacuum environment. The reactor was placed in the photocatalytic activity evaluation system, and the cooling circulation device was turned on to control the temperature of the reaction system at 6 °C. A 300 W xenon lamp (420 nm long-pass filter) was turned on, and the distance between the light source and the reactor was controlled at 12 cm. The stirring speed was adjusted to 400 rpm, and the reaction was irradiated for 4 h. The hydrogen production was detected in real time using an online gas chromatograph (nitrogen as the carrier gas), and the cumulative hydrogen production within 4 h was measured to be 59.16 mmol·g. -1 The hydrogen evolution rate was 14.79 mmol·g. -1 ·h -1 .

[0043] After the reaction was completed, the catalyst was collected by centrifugation, washed four times each with ethanol and deionized water, and then dried under vacuum at 60 °C. The above catalytic hydrolysis hydrogen production steps were repeated, and after five cycles, the hydrogen evolution rate remained at 13.5 mmol·g. -1 ·h -1 This indicates that the structure of the catalyst has not changed.

[0044] Example 2 The difference from Example 1 is that the molar ratio of copper ions to cobalt ions is 1:0.75, and all other conditions are the same, to obtain CNO@CuCoMOF-0.75.

[0045] The aforementioned CNO@CuCoMOF-0.75 was used for catalytic hydrolysis to produce hydrogen, following the same process as in Example 1. The amount of hydrogen produced was monitored in real-time using an online gas chromatograph (nitrogen as the carrier gas), and the hydrogen evolution rate was measured to be 12.38 mmol·g. -1 ·h -1 .

[0046] Example 3 The difference from Example 1 is that the molar ratio of copper ions to cobalt ions is 1:1.25, and all other conditions are the same, to obtain CNO@CuCoMOF-1.25.

[0047] The aforementioned CNO@CuCoMOF-1.25 was used for catalytic hydrolysis to produce hydrogen, following the same process as in Example 1. The amount of hydrogen produced was monitored in real-time using an online gas chromatograph (nitrogen as the carrier gas), and the hydrogen evolution rate was measured to be 10.56 mmol·g. -1 ·h -1 .

[0048] Comparative Example 1 Graphite-phase carbon nitride (g-C3N4) was directly used as the photocatalyst. The specific process for photocatalytic water splitting to produce hydrogen was the same as in Example 1. The amount of hydrogen produced was detected in real time using an online gas chromatograph (nitrogen as the carrier gas), and the hydrogen evolution rate was measured to be 0.31 mmol·g. -1 ·h -1 .

[0049] Comparative Example 2 The CNO prepared in Example 1 was used as the photocatalyst. The specific process for photocatalytic water splitting to produce hydrogen was the same as in Example 1. The amount of hydrogen produced was detected in real time using an online gas chromatograph (nitrogen as the carrier gas), and the hydrogen evolution rate was measured to be 0.31 mmol·g. -1 ·h -1 .

[0050] Compared with using graphitic carbon nitride (g-C3N4) directly as a photocatalyst, CNO as a photocatalyst did not improve the hydrogen evolution rate, indicating that CNO has limited hydrogen production activity.

[0051] Comparative Example 3 5g of graphitic carbon nitride (g-C3N4) yellow powder was dispersed in 100mL of a mixed acid of concentrated nitric acid and concentrated sulfuric acid (volume ratio of concentrated nitric acid to concentrated sulfuric acid was 2:1). The mixture was stirred at room temperature for 12h. After the reaction was completed, the mixture was washed with a large amount of deionized water until neutral, filtered, dried under vacuum at 60℃ for 12h, and ground to obtain oxidized graphitic carbon nitride powder, denoted as CNO.

[0052] 0.1 g CNO was dispersed in 15 mL of copper nitrate solution (composed of 0.242 g Cu(NO3)2・3H2O and 15 mL deionized water) and ultrasonically dispersed for 1.5 h to obtain a dispersion. 0.421 g H3BTC was weighed and dissolved in a mixed solution composed of 15 mL anhydrous ethanol and 15 mL LDM to obtain an H3BTC solution. The H3BTC solution was added to the above dispersion and stirred for 0.5 h. The mixture was then transferred to a 100 mL polytetrafluoroethylene-lined high-pressure reactor and reacted at 120 °C for 12 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed 5 times each with anhydrous ethanol and deionized water, and finally vacuum dried at 60 °C for 24 h to obtain the Cu-MOF modified carbon nitride microsphere catalyst, denoted as CNO@CuMOF.

[0053] Using the aforementioned CNO@CuMOF as the photocatalyst, the specific process for photocatalytic water splitting to produce hydrogen is the same as in Example 1. The amount of hydrogen produced was detected in real-time using an online gas chromatograph (nitrogen as the carrier gas), and the hydrogen evolution rate was measured to be 5.18 mmol·g. -1 ·h -1 This is 35% of the hydrogen production efficiency of Example 1.

[0054] Comparative Example 4 5g of graphitic carbon nitride (g-C3N4) yellow powder was dispersed in 100mL of a mixed acid of concentrated nitric acid and concentrated sulfuric acid (volume ratio of concentrated nitric acid to concentrated sulfuric acid was 2:1). The mixture was stirred at room temperature for 12h. After the reaction was completed, the mixture was washed with a large amount of deionized water until neutral, filtered, dried under vacuum at 60℃ for 12h, and ground to obtain oxidized graphitic carbon nitride powder, denoted as CNO.

[0055] Prepare a 15 mL mixed solution of copper nitrate and cobalt nitrate (composed of 0.242 g Cu(NO3)2·3H2O, 0.291 g Co(NO3)2·6H2O, and 15 mL deionized water, with a molar ratio of copper ions to cobalt ions of 1:1), and ultrasonically disperse for 1.5 h. Weigh 0.421 g H3BTC and dissolve it in a mixed solution composed of 15 mL anhydrous ethanol and 15 mL DMF to obtain an H3BTC solution. Add the H3BTC solution to the above mixed solution, stir for 0.5 h, transfer to a 100 mL polytetrafluoroethylene-lined high-pressure reactor, and react at 120 °C for 12 h. After the reaction is completed, cool to room temperature, centrifuge, wash 5 times each with anhydrous ethanol and deionized water, and finally vacuum dry at 60 °C for 24 h to obtain CuCoMOF.

[0056] Then, CNO and CuCoMOF were mixed at a mass ratio of 1:4 as a photocatalyst, and photocatalytic water splitting to produce hydrogen was carried out according to the steps of Example 1. The amount of hydrogen produced was detected in real time using an online gas chromatograph (nitrogen as the carrier gas), and the hydrogen evolution rate was measured to be 3.21 mmol·g. -1 ·h -1 The hydrogen production rate is significantly lower than that of Example 1 of this invention, indicating that physical mixing cannot form a tight heterojunction interface, the charge separation efficiency is low, and the hydrogen production activity is far lower than that of the catalyst prepared by the in-situ recombination method of this invention.

[0057] Comparative Example 5 The difference from Example 1 is that the pH was adjusted to 7.0 during the photocatalytic hydrogen production process, while all other conditions remained the same. The amount of hydrogen produced was monitored in real time using an online gas chromatograph (nitrogen as the carrier gas), and the hydrogen evolution rate was measured to be 8.45 mmol·g⁻¹. -1 ·h -1 It is evident that a suitable pH value is conducive to the smooth progress of photocatalytic hydrogen production, while an unsuitable pH value leads to a decrease in charge separation efficiency.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a bimetallic framework-modified carbon nitride microsphere catalyst, characterized in that, Includes the following steps: (1) Mix g-C3N4 with concentrated nitric acid and concentrated sulfuric acid and perform oxidation treatment to obtain oxidized graphitic carbon nitride; (2) Oxidized graphitic carbon nitride, mixed salt solution and 1,3,5-benzenetricarboxylic acid were mixed and subjected to hydrothermal reaction to obtain bimetallic framework modified carbon nitride microsphere catalyst.

2. The method for preparing the bimetallic framework modified carbon nitride microsphere catalyst according to claim 1, characterized in that, In step (1), the mass-volume ratio of g-C3N4 to concentrated nitric acid and concentrated sulfuric acid is 4~6g:60~70mL:30~35mL.

3. The method for preparing the bimetallic framework modified carbon nitride microsphere catalyst according to claim 1 or 2, characterized in that, In step (1), the oxidation treatment is carried out at room temperature for 6 to 14 hours.

4. The method for preparing the bimetallic framework modified carbon nitride microsphere catalyst according to claim 3, characterized in that, In step (2), the salts in the mixed salt solution are copper salts and cobalt salts: the molar ratio of copper ions to cobalt ions in the mixed salt solution is 1:0.5~1.

25.

5. The method for preparing the bimetallic framework modified carbon nitride microsphere catalyst according to claim 4, characterized in that, The mass ratio of the oxidized modified graphitic carbon nitride to copper and cobalt salts is 0.05~0.2:0.2~0.3:0.2~0.

4.

6. The method for preparing the bimetallic framework modified carbon nitride microsphere catalyst according to claim 4 or 5, characterized in that, The mass ratio of the copper salt to 1,3,5-benzenetricarboxylic acid is 0.2~0.3:0.4~0.

5.

7. The method for preparing the bimetallic framework modified carbon nitride microsphere catalyst according to claim 6, characterized in that, In step (2), the temperature of the hydrothermal reaction is 100~140℃ and the time of the hydrothermal reaction is 10~14h.

8. The bimetallic framework modified carbon nitride microsphere catalyst prepared by the method of any one of claims 1 to 7.

9. The application of the bimetallic framework modified carbon nitride microsphere catalyst according to claim 8 in catalytic water splitting for hydrogen production, characterized in that, An aqueous photocatalytic reaction system was constructed using bimetallic framework-modified carbon nitride microspheres as photocatalysts, eosin Y as photosensitizer, and triethanolamine as electron donor.

10. The application of the bimetallic framework modified carbon nitride microsphere catalyst according to claim 9 in catalytic water splitting for hydrogen production, characterized in that, The specific steps for hydrogen production by hydrolysis are as follows: dispersing bimetallic framework modified carbon nitride microsphere catalyst, eosin Y and triethanolamine in water, adjusting the pH value and then carrying out the reaction.

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