A nitrogen-doped carbon polyhedral-sulfide composite photocatalyst and a preparation method and application thereof

Abstract

The application discloses a nitrogen-doped carbon polyhedron-sulfide composite photocatalyst and a preparation method and application thereof, and the preparation process is as follows: nitrogen-doped carbon polyhedron nonmetal cocatalyst powder is added into deionized water, after ultrasonic treatment, cadmium acetate is added, stirring is carried out, NaOH aqueous solution is added, then thioacetamide is added, uniform stirring is carried out, and hydrothermal reaction is carried out at 160-200 DEG C for 16-24 hours, so that the nitrogen-doped carbon polyhedron-sulfide composite photocatalyst is obtained. In the NCP@CdS composite photocatalyst prepared in the application, the nitrogen-doped carbon skeleton in the NCP provides an electron transmission channel and provides active sites required by a reaction, so that effective charge separation and migration from CdS to NCP are realized. Compared with original CdS, the NCP@CdS composite photocatalyst provided by the application exhibits more excellent visible light catalytic hydrogen production performance under different sacrificial agent systems.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy production, and relates to photocatalytic clean preparation technology of hydrogen energy, and in particular to a nitrogen-doped carbon polyhedron-sulfide composite photocatalyst and its preparation method and application. Background Technology

[0002] The extensive use of fossil fuels is causing global energy shortages and environmental pollution. Hydrogen, as a promising energy carrier, can be derived from and produce water, effectively addressing the problems caused by fossil fuels, and has thus received increasingly widespread research and application. Among numerous hydrogen production methods, solar-powered hydrogen production has always been a potential candidate and a research hotspot. However, photocatalysis suffers from low utilization of photogenerated carriers and slow surface chemical reaction rates, significantly limiting the development of solar-powered hydrogen production. Therefore, researching and developing usable photocatalytic materials with rapid carrier transfer and separation is considered a feasible method to achieve commercial hydrogen production. Among these methods, supported cocatalysts are an attractive strategy for suppressing photogenerated carrier recombination and can significantly improve the reactivity of photocatalysts.

[0003] Currently, most photocatalytic systems utilize metal-based cocatalysts, which are expensive and prone to environmental damage during development and utilization. While noble metals such as Pt, Pd, Ru, and Rh exhibit excellent catalytic performance, their high cost and low abundance limit their wider application. Furthermore, metal-free cocatalysts such as MoS2, NiS2, CoP, W2N3, and transition metals have been extensively studied due to their good electrical conductivity. However, metal mining still impacts the environment, hindering global environmental pollution control. Therefore, developing novel non-metallic cocatalysts is crucial for achieving high-level, environmentally friendly hydrogen production. Summary of the Invention

[0004] The purpose of this invention is to provide a nitrogen-doped carbon polyhedron-sulfide composite photocatalyst, its preparation method and application, so as to achieve efficient photocatalytic preparation of green and clean energy.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst includes the following steps:

[0007] Nitrogen-doped carbon polyhedral nonmetallic cocatalyst powder was added to deionized water, sonicated, and then cadmium acetate was added. After stirring, NaOH aqueous solution was added, followed by thioacetamide. The mixture was stirred until homogeneous and then subjected to hydrothermal reaction at 160-200℃ for 16-24 hours to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst.

[0008] Furthermore, the amount of nitrogen-doped carbon polyhedral nonmetallic cocatalyst used is 1%-6% of the theoretical mass of CdS.

[0009] Furthermore, the ultrasound session lasts 15-30 minutes.

[0010] Furthermore, the ratio of cadmium acetate to deionized water was 20 mmol: 50 mL.

[0011] Furthermore, the ratio of cadmium acetate to NaOH aqueous solution was 20 mmol: 10 mL, and the concentration of NaOH aqueous solution was 4 mol / L.

[0012] Furthermore, the molar ratio of cadmium acetate to thioacetamide is 20:25.

[0013] Furthermore, the nitrogen-doped carbon polyhedral nonmetallic cocatalyst is prepared through the following process:

[0014] ZIF-8 powder was calcined at 800℃-1100℃ for 4-6 hours, then added to hydrochloric acid solution, homogenized, and dried to obtain nitrogen-doped carbon polyhedral nonmetallic cocatalyst.

[0015] Furthermore, the ratio of ZIF-8 powder to hydrochloric acid solution is 400mg-600mg: 200mL-400mL, and the concentration of hydrochloric acid solution is 2mol / L; the temperature is increased to 800℃-1100℃ at a heating rate of 3℃ / min.

[0016] A nitrogen-doped carbon polyhedral-sulfide composite photocatalyst prepared according to the method described above.

[0017] Application of a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst as described above in photocatalytic hydrogen production under visible light.

[0018] Furthermore, a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst was added to the reactor, followed by the addition of a sacrificial agent. After purging with argon gas, the photocatalytic hydrogen production reaction was carried out under stirring. The sacrificial agent was a mixed solution of 0.25 mol / L Na2SO3 aqueous solution and 0.35 mol / L Na2S aqueous solution, a 10% triethanolamine aqueous solution, or a 10 mmol / L benzyl alcohol aqueous solution.

[0019] Furthermore, the ratio of nitrogen-doped carbon polyhedral-sulfide composite photocatalyst to sacrificial agent is 10 mg: 80 mL.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention employs a one-pot hydrothermal method to anchor a CdS photocatalyst onto the surface of a nitrogen-doped carbon polyhedral nonmetallic cocatalyst powder, yielding the composite photocatalyst NCP@CdS. Utilizing the ability of cadmium sulfide to generate photogenerated carriers and the co-catalytic properties of the nitrogen-doped carbon polyhedral nonmetallic cocatalyst powder, a Modigliani-Schottky junction is formed between the two powders due to the difference in their work functions. This accelerates the separation and migration of photogenerated carriers, allowing more photogenerated electrons to reach the reaction site more quickly and interact with H+. + The reaction produces hydrogen gas. The nitrogen-doped carbon polyhedral non-metallic cocatalyst powder used in this invention is a non-metallic material, which can effectively reduce the cost of photocatalytic hydrogen production. By reducing the proportion of metal elements in the photocatalytic system, the environmental impact of catalyst preparation can be effectively mitigated. The nitrogen-doped carbon polyhedron exhibits the ability to accelerate the reaction under different sacrificial agent systems, indicating that this invention has good reproducibility and universality.

[0022] In the nitrogen-doped carbon polyhedron-sulfide composite photocatalyst prepared in this invention, namely the NCP@CdS composite photocatalyst, the nitrogen-doped carbon framework in NCP provides electron transfer channels, and nitrogen atoms provide chemical reaction active sites, thereby realizing the effective charge separation and migration from CdS to NCP and promoting the photocatalytic hydrogen production reaction. Compared with the original CdS, the NCP@CdS composite photocatalyst proposed in this invention exhibits superior visible light photocatalytic hydrogen production performance under different sacrificial agent systems, and also has good hydrogen production stability. Under the condition of using aqueous solutions containing Na2SO3 and Na2S (Na2SO3 concentration of 0.25 mol / L and Na2S concentration of 0.35 mol / L) as sacrificial agents, the visible light photocatalytic hydrogen production activity can reach as high as 13.89 mmol h⁻¹. -1 g -1 This invention provides a new approach for constructing efficient and low-cost photocatalytic systems. Attached Figure Description

[0023] Figure 1 These are X-ray diffraction (XRD) patterns of cadmium sulfide (CdS) and nitrogen-doped carbon polyhedral-sulfide composite photocatalysts (NCP@CdS) in Examples 1-3 and Comparative Examples 1-4.

[0024] Figure 2 This is a transmission electron microscope (TEM) image of the nitrogen-doped carbon polyhedron-sulfide composite photocatalyst (NCP@CdS) from Example 2.

[0025] Figure 3The graph shows the photocatalytic hydrogen production rate of nitrogen-doped carbon polyhedral-sulfide composite photocatalysts (NCP@CdS) in Examples 1-3 and Comparative Example 4 under the condition of using a mixed solution of 0.25 mol / L Na2SO3 and 0.35 mol / L Na2S as sacrificial agents.

[0026] Figure 4 This is a stability test diagram of the nitrogen-doped carbon polyhedron-sulfide composite photocatalyst (NCP@CdS-3) in Example 2, using a mixed solution of 0.25 mol / L Na2SO3 and 0.35 mol / L Na2S as sacrificial agents for photocatalytic hydrogen production.

[0027] Figure 5 These are the photocatalytic hydrogen production activity diagrams of the nitrogen-doped carbon polyhedron-sulfide composite photocatalyst (NCP@CdS-3) under different sacrificial agent conditions in Examples 2, 4, and 5. Detailed Implementation

[0028] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0029] The NCP@CdS composite photocatalyst provided by this invention promotes the separation and migration efficiency of photogenerated carriers and exhibits excellent visible light photocatalytic hydrogen production performance under different sacrificial agent systems, providing a new approach for constructing efficient and low-cost photocatalytic systems.

[0030] This invention discloses a method for preparing a nitrogen-doped carbon polyhedron-sulfide composite photocatalyst. The method involves high-temperature calcination of a zeolite imidazole ester framework material (ZIF-8) followed by hydrochloric acid treatment to obtain a non-metallic cocatalyst, nitrogen-doped carbon polyhedron (NCP). The nitrogen-doped carbon polyhedron non-metallic cocatalyst powder (NCP) derived from ZIF-8 serves as a novel non-metallic cocatalyst. Subsequently, CdS particles are anchored onto the surface of the nitrogen-doped carbon polyhedron using a hydrothermal synthesis method, ultimately yielding the nitrogen-doped carbon polyhedron-sulfide composite photocatalyst, i.e., the NCP@CdS composite photocatalyst. The method specifically includes the following steps:

[0031] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 400-600 mg of ZIF-8 white powder was placed in an Ar atmosphere tube furnace and calcined at 800-1100℃ for 4-6 hours, with a heating rate of 3℃ / min. The resulting black powder was added to 200-400 mL of 2 mol / L hydrochloric acid solution and vigorously stirred at 25℃ for 18-24 hours until homogeneous. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then placed under vacuum at 60℃ to recover NCP for later use.

[0032] Step 2: Preparation of NCP@CdS composite photocatalyst using hydrothermal reaction. Based on the expected theoretical yield of CdS, NCP powders of different mass ratios were added to 50 mL of deionized water and sonicated for 15-30 minutes to suspend them. Then, 20 mmol of cadmium acetate was added and stirred for 15-30 minutes to obtain a black mixed suspension. Subsequently, an excess of 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the dropwise addition. After stirring evenly, 25 mmol of thioacetamide was added and stirring was continued for 15-30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 160-200 °C for 16-24 hours. After the reaction, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and then placed under vacuum at 60 °C to recover the NCP@CdS composite photocatalyst for later use.

[0033] Based on the expected theoretical yield of CdS, different nitrogen-doped carbon polyhedral-sulfide composite photocatalysts (NCP@CdS) were prepared by using NCP with different theoretical CdS mass percentages (1%-6%, with 1%, 3% and 6% being preferred), and named NCP@CdS-1, NCP@CdS-3 and NCP@CdS-6, respectively.

[0034] The application of nitrogen-doped carbon polyhedron-sulfide composite photocatalyst (NCP@CdS) in photocatalytic water splitting follows these steps: The nitrogen-doped carbon polyhedron-sulfide composite photocatalyst (NCP@CdS) is added to a reactor, followed by the addition of the required sacrificial agent. After purging with argon gas, the photocatalytic hydrogen production reaction is carried out under stirring. The sacrificial agent is an aqueous solution containing Na₂SO₃ and Na₂S, a 10% (v / v) triethanolamine aqueous solution, or a 10 mmol / L benzyl alcohol aqueous solution, added in a volume of 80 mL. The concentration of Na₂SO₃ in the aqueous solution containing Na₂SO₃ and Na₂S is 0.25 mol / L, and the concentration of Na₂S is 0.35 mol / L.

[0035] Example 1

[0036] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 400 mg of ZIF-8 white powder was calcined at 800 °C for 5 hours in an Ar atmosphere tube furnace, with a heating rate of 3 °C / min. The resulting black powder was placed in 300 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 18 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then the NCP powder was recovered under vacuum at 60 °C for later use.

[0037] Step 2: 28.9 mg of NCP powder was added to 50 mL of deionized water and sonicated for 30 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Then, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the dropwise addition. After stirring evenly, 25 mmol of thioacetamide was added and stirring was continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction was completed, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS-1.

[0038] Step 3: Add 10 mg NCP@CdS-1 to a 105 mL reactor, followed by the addition of a sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0039] Example 2

[0040] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 400 mg of ZIF-8 white powder was calcined at 800 °C for 5 hours in an Ar atmosphere tube furnace, with a heating rate of 3 °C / min. The resulting black powder was placed in 300 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 18 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then the NCP powder was recovered under vacuum at 60 °C for later use.

[0041] Step 2: 86.7 mg of NCP powder was added to 50 mL of deionized water and sonicated for 30 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Then, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the dropwise addition. After stirring evenly, 25 mmol of thioacetamide was added and stirring was continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction was completed, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS-3.

[0042] Step 3: Add 10 mg NCP@CdS-3 to a 105 mL reactor, followed by 80 mL of sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0043] Example 3

[0044] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 400 mg of ZIF-8 white powder was calcined at 800 °C for 5 hours in an Ar atmosphere tube furnace, with a heating rate of 3 °C / min. The resulting black powder was placed in 300 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 18 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then the NCP powder was recovered under vacuum at 60 °C for later use.

[0045] Step 2: 173.4 mg of NCP powder was added to 50 mL of deionized water and sonicated for 30 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Then, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the dropwise addition. After stirring evenly, 25 mmol of thioacetamide was added and stirring was continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction was completed, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS-6.

[0046] Step 3: Add 10 mg NCP@CdS-6 to a 105 mL reactor, followed by 80 mL of sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0047] Example 4

[0048] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 400 mg of ZIF-8 white powder was calcined at 800 °C for 5 hours in an Ar atmosphere tube furnace, with a heating rate of 3 °C / min. The resulting black powder was placed in 300 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 18 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then the NCP powder was recovered under vacuum at 60 °C for later use.

[0049] Step 2: 86.7 mg of NCP powder was added to 50 mL of deionized water and sonicated for 30 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Then, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the dropwise addition. After stirring evenly, 25 mmol of thioacetamide was added and stirring was continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction was completed, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS-3.

[0050] Step 3: Add 10 mg NCP@CdS-3 to a 105 mL reactor, followed by 80 mL of 10 mmol / L benzyl alcohol aqueous solution as a sacrificial agent. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0051] Example 5

[0052] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 400 mg of ZIF-8 white powder was calcined at 800 °C for 5 hours in an Ar atmosphere tube furnace, with a heating rate of 3 °C / min. The resulting black powder was placed in 300 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 18 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then the NCP powder was recovered under vacuum at 60 °C for later use.

[0053] Step 2: 86.7 mg of NCP powder was added to 50 mL of deionized water and sonicated for 30 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Then, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the dropwise addition. After stirring evenly, 25 mmol of thioacetamide was added and stirring was continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction was completed, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS-3.

[0054] Step 3: Add 10 mg NCP@CdS-3 to a 105 mL reactor, then add 80 mL of 10% triethanolamine aqueous solution as a sacrificial agent. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0055] Comparative Example 1

[0056] Step 1: Add 20 mmol of cadmium acetate to 50 mL of deionized water and stir for 30 minutes. Then, slowly add 10 mL of 4 mol / L NaOH aqueous solution. Cadmium hydroxide is generated during the addition. After stirring evenly, add 25 mmol of thioacetamide and continue stirring for 30 minutes. Finally, pour the resulting mixed solution into a 100 mL hydrothermal reactor and react at 180 °C for 24 hours. After the reaction is complete, collect the final product by centrifugation, wash several times with deionized water and anhydrous ethanol, and recover it under vacuum at 60 °C to obtain CdS.

[0057] Step 2: Add 10 mg CdS to a 105 mL reactor, followed by 80 mL of a mixed solution of 0.25 mol / L Na2SO3 and 0.35 mol / L Na2S as a sacrificial agent. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0058] Comparative Example 2

[0059] Step 1: Add 20 mmol of cadmium acetate to 50 mL of deionized water and stir for 30 minutes. Then, slowly add 10 mL of 4 mol / L NaOH aqueous solution. Cadmium hydroxide is generated during the addition. After stirring evenly, add 25 mmol of thioacetamide and continue stirring for 30 minutes. Finally, pour the resulting mixed solution into a 100 mL hydrothermal reactor and react at 180 °C for 24 hours. After the reaction is complete, collect the final product by centrifugation, wash several times with deionized water and anhydrous ethanol, and recover it under vacuum at 60 °C to obtain CdS.

[0060] Step 2: Add 10 mg CdS to a 105 mL reactor, followed by 80 mL of 10 mmol / L benzyl alcohol aqueous solution as a sacrificial agent. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0061] Comparative Example 3

[0062] Step 1: Add 20 mmol of cadmium acetate to 50 mL of deionized water and stir for 30 minutes. Then, slowly add 10 mL of 4 mol / L NaOH aqueous solution. Cadmium hydroxide is generated during the addition. After stirring evenly, add 25 mmol of thioacetamide and continue stirring for 30 minutes. Finally, pour the resulting mixed solution into a 100 mL hydrothermal reactor and react at 180 °C for 24 hours. After the reaction is complete, collect the final product by centrifugation, wash several times with deionized water and anhydrous ethanol, and recover it under vacuum at 60 °C to obtain CdS.

[0063] Step 2: Add 10 mg CdS to a 105 mL reactor, then add 80 mL of 10% triethanolamine aqueous solution as a sacrificial agent. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0064] Comparative Example 4

[0065] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 400 mg of ZIF-8 white powder was calcined at 800 °C for 5 hours in an Ar atmosphere tube furnace, with a heating rate of 3 °C / min. The resulting black powder was placed in 300 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 18 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then recovered under vacuum at 60 °C for later use.

[0066] Step 2: Add 20 mmol of cadmium acetate to 50 mL of deionized water and stir for 30 minutes. Then, slowly add 10 mL of 4 mol / L NaOH aqueous solution. Cadmium hydroxide is generated during the addition. After stirring evenly, add 25 mmol of thioacetamide and continue stirring for 30 minutes. Finally, pour the resulting mixed solution into a 100 mL hydrothermal reactor and react at 180 °C for 24 hours. After the reaction is complete, collect the final product by centrifugation, wash several times with deionized water and anhydrous ethanol, and recover it under vacuum at 60 °C to obtain CdS.

[0067] Step 3: Grind and mix 30mg NCP and 100mg CdS thoroughly to obtain NCP / CdS-3.

[0068] Step 4: Add 10 mg NCP / CdS-3 to a 105 mL reactor, followed by 80 mL of sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0069] Example 6

[0070] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 400 mg of ZIF-8 white powder was calcined at 1100 °C for 4 hours in an Ar atmosphere tube furnace, with a heating rate of 3 °C / min. The resulting black powder was placed in 250 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 24 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and the NCP powder was recovered under vacuum at 60 °C for later use.

[0071] Step 2: NCP powder was added to 50 mL of deionized water and sonicated for 30 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Next, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the addition. After stirring evenly, 25 mmol of thioacetamide was added and stirring continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS. The mass of the NCP powder was 1% of the theoretical mass of CdS.

[0072] Step 3: Add 10 mg NCP@CdS to a 105 mL reactor, followed by 80 mL of sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0073] Example 7

[0074] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 500 mg of ZIF-8 white powder was calcined at 800 °C for 6 hours in an Ar atmosphere tube furnace at a heating rate of 3 °C / min. The resulting black powder was placed in 350 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 20 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and the NCP powder was recovered under vacuum at 60 °C for later use.

[0075] Step 2: NCP powder was added to 50 mL of deionized water and sonicated for 28 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Next, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the addition. After stirring evenly, 25 mmol of thioacetamide was added, and stirring continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS. The mass of the NCP powder was 2% of the theoretical mass of CdS.

[0076] Step 3: Add 10 mg NCP@CdS to a 105 mL reactor, followed by the addition of a sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0077] Example 8

[0078] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 600 mg of ZIF-8 white powder was calcined at 900 °C for 5 hours in an Ar atmosphere tube furnace, with a heating rate of 3 °C / min. The resulting black powder was placed in 400 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 21 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then the NCP powder was recovered under vacuum at 60 °C for later use.

[0079] Step 2: NCP powder was added to 50 mL of deionized water and sonicated for 25 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Next, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the addition. After stirring evenly, 25 mmol of thioacetamide was added, and stirring continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS. The mass of the NCP powder was 4% of the theoretical mass of CdS.

[0080] Step 3: Add 10 mg NCP@CdS to a 105 mL reactor, followed by 80 mL of sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0081] Example 9

[0082] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 550 mg of ZIF-8 white powder was calcined at 1000 °C for 4.5 hours in an Ar atmosphere tube furnace at a heating rate of 3 °C / min. The resulting black powder was placed in 300 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 22 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and then the NCP powder was recovered under vacuum at 60 °C for later use.

[0083] Step 2: NCP powder was added to 50 mL of deionized water and sonicated for 20 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Next, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the addition. After stirring evenly, 25 mmol of thioacetamide was added, and stirring continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS. The mass of the NCP powder was 5% of the theoretical mass of CdS.

[0084] Step 3: Add 10 mg NCP@CdS to a 105 mL reactor, followed by 80 mL of sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0085] Example 10

[0086] Step 1: First, nitrogen-doped carbon polyhedral nonmetallic cocatalysts were obtained through heat treatment and hydrochloric acid treatment. 450 mg of ZIF-8 white powder was calcined at 950 °C for 5 hours in an Ar atmosphere tube furnace at a heating rate of 3 °C / min. The resulting black powder was placed in 200 mL of 2 mol / L hydrochloric acid solution and stirred vigorously at 25 °C for 23 hours. The final product was collected by centrifugation, washed several times with deionized water and ethanol, and the NCP powder was recovered under vacuum at 60 °C for later use.

[0087] Step 2: NCP powder was added to 50 mL of deionized water and sonicated for 15 minutes to suspend it. Then, 20 mmol of cadmium acetate was added and stirred for 30 minutes to obtain a black mixed suspension. Next, 10 mL of 4 mol / L NaOH aqueous solution was slowly added dropwise. Cadmium hydroxide was generated during the addition. After stirring evenly, 25 mmol of thioacetamide was added, and stirring continued for 30 minutes. Finally, the resulting mixed solution was poured into a 100 mL hydrothermal reactor and reacted at 180 °C for 24 hours. After the reaction, the final product was collected by centrifugation, washed several times with deionized water and anhydrous ethanol, and recovered under vacuum at 60 °C to obtain a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst, denoted as NCP@CdS. The mass of the NCP powder was 5% of the theoretical mass of CdS.

[0088] Step 3: Add 10 mg NCP@CdS to a 105 mL reactor, followed by 80 mL of sacrificial agent, which is an aqueous solution containing Na2SO3 and Na2S. The concentration of Na2SO3 is 0.25 mol / L and the concentration of Na2S is 0.35 mol / L. Purge the reaction solution with argon gas for 30 minutes to remove air from the reaction system. After purging, stir the reaction under a visible xenon lamp light source.

[0089] Figure 1 The images show the X-ray diffraction (XRD) patterns of cadmium sulfide (CdS) and nitrogen-doped carbon polyhedral-sulfide composite photocatalyst (NCP@CdS). The resulting composite materials all exhibit characteristic peaks of cadmium sulfide (CdS), indicating that the addition of the non-metallic cocatalyst NCP does not affect the crystal structure of cadmium sulfide.

[0090] Figure 2 This is a transmission electron microscope (TEM) image of a nitrogen-doped carbon polyhedral-sulfide composite photocatalyst (NCP@CdS). It demonstrates that the resulting composite material consists of NCP and cadmium sulfide, and that the two form a heterojunction at their contact.

[0091] Figure 3 The graph shows the photocatalytic hydrogen evolution rate of nitrogen-doped carbon polyhedron-sulfide composite photocatalyst (NCP@CdS) under the condition of using a mixed solution of 0.25 mol / L Na2SO3 and 0.35 mol / L Na2S as sacrificial agents. The sample NCP@CdS-3 has the highest photocatalytic hydrogen evolution rate.

[0092] Figure 4 The image shows the photocatalytic hydrogen production stability test results of nitrogen-doped carbon polyhedron-sulfide composite photocatalyst (NCP@CdS-3) under the condition of using a mixed solution of 0.25 mol / L Na2SO3 and 0.35 mol / L Na2S as sacrificial agents, indicating that the catalyst has good stability.

[0093] Figure 5 The image shows the photocatalytic hydrogen production activity of nitrogen-doped carbon polyhedron-sulfide composite photocatalyst (NCP@CdS-3) under different sacrificial agent conditions, indicating that the co-catalyst NCP can promote the photocatalytic hydrogen production reaction under different systems.

[0094] The above description is only of the preferred embodiment of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0095] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. The application of a nitrogen-doped carbon polyhedron-cadmium sulfide composite photocatalyst in photocatalytic hydrogen production under visible light, characterized in that, The preparation method of the nitrogen-doped carbon polyhedron-cadmium sulfide composite photocatalyst includes the following steps: Nitrogen-doped carbon polyhedral nonmetallic cocatalyst powder was added to deionized water, ultrasonicated, cadmium acetate was added, stirred, NaOH aqueous solution was added, and then thioacetamide was added and stirred evenly. The mixture was then subjected to hydrothermal reaction at 160-200℃ for 16-24 hours to obtain nitrogen-doped carbon polyhedral-sulfide composite photocatalyst. The ratio of nitrogen-doped carbon polyhedral nonmetallic cocatalyst powder to deionized water is 86.7 mg: 50 mL; the ratio of cadmium acetate to deionized water is 20 mmol: 50 mL; the ratio of cadmium acetate to NaOH aqueous solution is 20 mmol: 10 mL; and the molar ratio of cadmium acetate to thioacetamide is 20:

25. The nitrogen-doped carbon polyhedral nonmetallic cocatalyst is prepared by the following process: ZIF-8 powder was calcined at 800℃-1100℃ for 4-6 hours, then added to hydrochloric acid solution, homogenized, and dried to obtain nitrogen-doped carbon polyhedral nonmetallic cocatalyst.

2. The application of the nitrogen-doped carbon polyhedron-cadmium sulfide composite photocatalyst according to claim 1 in photocatalytic hydrogen production under visible light, characterized in that, The ultrasound session lasts 15-30 minutes.

3. The application of the nitrogen-doped carbon polyhedron-cadmium sulfide composite photocatalyst according to claim 1 in photocatalytic hydrogen production under visible light, characterized in that, The concentration of the NaOH aqueous solution is 4 mol / L.

4. The application of the nitrogen-doped carbon polyhedron-cadmium sulfide composite photocatalyst according to claim 1 in photocatalytic hydrogen production under visible light, characterized in that, The ratio of ZIF-8 powder to hydrochloric acid solution is 400mg-600mg: 200mL-400mL, and the concentration of hydrochloric acid solution is 2mol / L; the temperature is increased to 800℃-1100℃ at a heating rate of 3℃ / min.

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