A Ni3ZnC 0.7 @C / g-C3N4 photocatalyst and its preparation method and application

Abstract

The present invention discloses a Ni3ZnC 0.7 @C / g-C3N4 photocatalyst and its preparation method and application, the preparation process includes combining hydrothermal method and solid phase sintering method, firstly using calcination method to prepare porous g-C3N4 nanosheets to increase the specific surface area of ​​the product and the active sites during photocatalytic hydrogen production; then using hydrothermal method to prepare NiZn-LDH / g-4 precursor, further carbonizing to obtain C-coated Ni3ZnC 0.7 Finally, Ni3ZnC with high hydrogen production efficiency was prepared by low temperature annealing. 0.7 @C / g‑C3N4 composite photocatalytic material; the preparation conditions are simple and easy to control, and the production cost is low; Ni3ZnC 0.7 Integrated with C, Ni3ZnC 0.7 @C forms a heterogeneous structure of carbon-coated spherical nanoparticles, which is beneficial to inhibit the agglomeration of nanoparticles and increase the Ni3ZnC 0.7 The specific surface area and active sites of the @C / g‑C3N4 composite photocatalyst and the carbon shell on the surface provide a fast charge transfer pathway for the rapid migration of electrons and ions in the electrochemical process, which can effectively promote the separation and transport of photogenerated charges, thereby effectively improving the hydrogen production efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, and relates to a photocatalyst, in particular to a Ni3ZnC 0.7 @C / g-C3N4 photocatalyst, its preparation method and application. Background Art

[0002] As the energy crisis intensifies, humanity has begun to seek green, environmentally friendly, and sustainable energy sources to replace fossil fuels. Hydrogen is considered an ideal alternative energy source due to its clean, pollution-free, widely available, and high calorific value. Among various hydrogen production methods, photocatalytic water splitting is considered a promising approach. To promote the industrialization of photocatalytic hydrogen production technology, the development of efficient photocatalysts remains a research priority. Graphitic carbon nitride (CN) is a visible-light-responsive photocatalyst with a unique two-dimensional structure, excellent chemical stability, and a tunable electronic structure. However, the photocatalytic activity of pure CN is limited due to the rapid recombination of photogenerated electron-hole pairs. To enhance the photocatalytic performance of CN, various methods have been developed to improve the photocatalytic activity of CN. Currently, the development of novel composite photocatalytic materials using g-C3N4 nanosheets as a matrix is ​​an important approach to improve the performance of photocatalytic hydrogen production and is of great significance for the further development of new composite photocatalytic materials. In the study of visible-light photocatalytic hydrogen production from g-C3N4 semiconductors, co-catalysts are required to further enhance the catalytic activity of the samples. To date, most co-catalysts are rare and expensive metals, which are very costly. Therefore, it is of great significance to develop co-catalysts with abundant content, low cost and excellent performance to enhance the photocatalytic activity of g-C3N4.

[0003] Transition metal carbides (TMC) (such as Fe3C, Co3C, Ni3C, etc.) are considered to be a typical class of metal interstitial compounds. Studies have shown that interstitial C atoms can expand the lattice distance between transition metals in TMC, resulting in the contraction of the transition metal d-band center and the increase of the state density near the Fermi level, which will give TMC unique surface adsorption properties, and the electronic structure is significantly similar to Pt. Compared with single metal carbides, bimetallic carbides have the advantages of adjustable active sites, adjustable electronic structure, and adjustable coordination environment, and have broad application prospects in the field of energy conversion and storage. Among them, Ni3ZnC 0.7 Due to its excellent perovskite-like metallic conductivity and structural stability, it can be used as a potential bimetallic carbide catalyst for hydrogen evolution reaction (HER). However, due to insufficient catalytic active sites and unoptimized electronic and electronic structure, Ni3ZnC 0.7 The catalytic performance of Ni3ZnC is not ideal. 0.7The preparation of nanostructured nanoparticles usually requires a relatively harsh high-temperature pyrolysis process, which will inevitably lead to the agglomeration or coarsening of the nanoparticles, which largely reduces the exposure of active sites. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a Ni3ZnC 0.7 @C / g-C3N4 photocatalyst and its preparation method and application, Ni3ZnC 0.7 The heterogeneous structure in which @C nanoparticles are uniformly loaded on g-C3N4 nanosheets has a large specific surface area and multiple active sites, high hydrogen production efficiency, simple and easy-to-control preparation conditions, and low production cost.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A Ni3ZnC 0.7 The preparation method of @C / g-C3N4 photocatalyst comprises the following steps:

[0007] Step 1: Prepare nanosheet g-C3N4 by a one-step calcination method;

[0008] Step 2: nickel chloride, zinc acetate, urea and acetylacetone are mixed in a molar ratio of (1-3): (1-2): (1-5): (0.1-0.6) to obtain a mixed powder, and then the mixed powder and the nano-sheet g-C3N4 prepared in step 1 are mixed in a mass ratio of 1: (1-6), water and ethylene glycol mixture are added, ultrasonic treatment is performed, and then stirring is performed until uniform dispersion is obtained, and then the mixture is poured into the lining of the reactor, placed in a vacuum drying oven at 100-160 ° C for 10-16 hours, and after the temperature in the oven drops to room temperature, the reactor is taken out, centrifuged, washed, and dried to obtain NiZn-LDH / g-C3N4;

[0009] Step 3: Mix the NiZn-LDH / g-C3N4 prepared in step 2 with melamine in a mass ratio of (0.5-4): (1-10), grind and spread on a porcelain boat and then place it in a tube furnace. Under an argon atmosphere, heat the tube furnace at a rate of 5-10°C / min to 500-700°C, keep warm for 2-4h, and after the product is cooled, take out and grind to obtain Ni3ZnC 0.7 @C co-catalyst;

[0010] Step 4: First, the Ni3ZnC prepared in step 3 0.7The @C co-catalyst and the nano-sheet g-C3N4 prepared in step 1 are mixed in a mass ratio of (0.5-1): (5-10) and placed in a tube furnace. The tube furnace is heated to 200-400°C at a rate of 2-5°C / min under an argon atmosphere and kept warm for 1-3 hours. After the product is cooled, it is taken out to obtain Ni3ZnC 0.7 @C / g-C3N4 photocatalyst.

[0011] The present invention also has the following technical features:

[0012] Preferably, the specific steps of preparing nano-sheet g-C3N4 by the one-step calcination method described in step 1 include:

[0013] Urea and dicyandiamide are sequentially added to a beaker containing a sulfuric acid solution in a mass ratio of (1-5):(1-3), and stirred for 1-3 hours. Finally, the mixed solution is heated in a water bath at a temperature of 60-80°C for 1-6 hours. After the reaction is completed, the cooled reaction solution is poured out, centrifuged, and washed to obtain solid A.

[0014] The volume ratio of 1M concentrated sulfuric acid to ultrapure water in the sulfuric acid solution is (1-2):(2-5);

[0015] Solid A is spread flat on a porcelain boat, placed in a tube furnace under air atmosphere, heated to 450-600°C at a rate of 2-10°C / min, and kept warm for 1-4 hours. After calcination, the sample is naturally cooled in the furnace and ground to obtain yellow powder B, i.e., flaky g-C3N4.

[0016] Preferably, the volume ratio of ethylene glycol to ultrapure water in the water and ethylene glycol mixture described in step 2 is (1-2):(3-5).

[0017] Preferably, the ultrasonic treatment time in step 2 is 30-120 min.

[0018] Preferably, the stirring in step 2 is performed on a magnetic stirrer for 60-150 minutes.

[0019] Preferably, the washing is performed with deionized water and anhydrous ethanol for 3-5 times respectively.

[0020] Preferably, the drying in step 2 is carried out in a vacuum drying oven for 10-20 hours.

[0021] Preferably, the grinding is performed in a mortar for 30-120 minutes.

[0022] The present invention also protects a Ni3ZnC prepared by the method as described above 0.7 @C / g-C3N4 photocatalyst and its application in photocatalytic hydrogen production.

[0023] Compared with the prior art, the present invention has the following technical effects:

[0024] The present invention is used to prepare Ni3ZnC 0.7 In the process of preparing @C / g-C3N4 composite photocatalytic materials, the hydrothermal method and solid phase sintering method are combined. First, g-C3N4 nanosheets are prepared by calcination method, and then NiZn-LDH / g-C3N4 precursor is prepared by hydrothermal method, which is further carbonized to obtain C-coated Ni3ZnC 0.7 Materials, Ni3ZnC through interface electronic engineering 0.7 Integrated with C, Ni3ZnC 0.7 @C forms a heterogeneous structure of carbon-coated spherical nanoparticles, which is beneficial to inhibit the agglomeration of nanoparticles and increase the Ni3ZnC 0.7 The specific surface area and active sites of @C / g-C3N4 composite photocatalysts are improved, and the carbon shell on the surface provides a fast charge transfer pathway for the rapid migration of electrons and ions in the electrochemical process, which can effectively promote the separation and transport of photogenerated charges. Finally, Ni3ZnC with high hydrogen production efficiency was prepared by low temperature annealing. 0.7 @C / g-C3N4 composite photocatalytic material; preparation conditions are simple and easy to control, and production cost is low;

[0025] The porous g-C3N4 nanosheets prepared by the present invention further increase the specific surface area of ​​the product and the active sites during photocatalytic hydrogen production, thereby effectively improving the hydrogen production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Ni3ZnC prepared in Example 1 0.7 X-ray diffraction analysis diagram of @C / g-C3N4, where the horizontal axis is the 2θ angle and the vertical axis is the diffraction peak intensity;

[0027] Figure 2 Ni3ZnC prepared in Example 1 0.7 @C / g-C3N4 scanning image at 5μm;

[0028] Figure 3 Ni3ZnC prepared in Example 1 0.7 Hydrogen evolution performance diagram of @C / g-C3N4. DETAILED DESCRIPTION

[0029] The specific contents of the present invention are further explained in detail below with reference to the embodiments.

[0030] Example 1:

[0031] Step 1: Urea and dicyandiamide are placed in a beaker containing a sulfuric acid solution in a mass ratio of 5:3, wherein the volume ratio of 1M concentrated sulfuric acid to ultrapure water is 1:3, and then stirred for 2 hours. Finally, the mixed solution is placed in a water bath and heated for 4 hours at a temperature of 70°C. After the reaction is completed, the cooled reaction solution is poured out and centrifuged, and washed three times with deionized water and anhydrous ethanol respectively to obtain solid A;

[0032] 4 g of solid A was spread flat on a porcelain boat and calcined in air at 550°C for 4 h at a heating rate of 5°C / min.

[0033] After calcination, the sample was cooled naturally in the furnace and ground in a mortar for 60 min to obtain yellow powder B, i.e., flaky g-C3N4;

[0034] Step 2: Nickel chloride, zinc acetate, urea, and acetylacetone were prepared in a molar ratio of 3:1:4:0.4, and then mixed with powder B in a ratio of 1:5 to obtain mixed powder C. 50 mL of ethylene glycol solution was added, wherein the volume ratio of ethylene glycol to ultrapure water was 2:3. The mixture was ultrasonicated for 120 minutes and then stirred on a magnetic stirrer for 100 minutes. The mixture was then quickly poured into the liner of a 150 mL reactor.

[0035] The operating temperature of the vacuum drying oven was set to 140°C. After the temperature in the drying oven rose to the set temperature, the sealed reactor was placed in the oven and kept warm for 14 hours. After the temperature in the oven dropped to room temperature, the reactor was taken out and cooled. The cooled reaction solution was poured out and centrifuged, and washed three times with deionized water and anhydrous ethanol respectively to obtain a precipitate. The precipitate was then placed in a vacuum drying oven and dried at 80°C for 10 hours to obtain solid D, i.e., NiZn-LDH / g-C3N4.

[0036] Step 3: Mix solid D and melamine in a mass ratio of 2:5, and grind them in a mortar for 30 minutes to obtain powder E. Spread powder E flat on a porcelain boat and place it in a tube furnace. Then evacuate the tube furnace to a vacuum state, and then slowly introduce argon gas. Repeat this operation three times until all the air in the tube furnace is exhausted. Then, heat the tube furnace to 550°C at a heating rate of 10°C / min, and then keep it warm for 2 hours. After the product cools, take it out and grind it for 60 minutes to obtain powder F, that is, Ni3ZnC 0.7 @C co-catalyst;

[0037] Step 4: First, mix powder F and powder B in a mass ratio of 1:5, then evacuate the tube furnace to a vacuum state, slowly introduce argon, and repeat the operation three times until all the air in the tube furnace is exhausted. Then, heat the tube furnace to 300°C at a rate of 2°C / min, and then keep it warm for 2 hours. After the product cools down, take it out to obtain Ni3ZnC 0.7@C / g-C3N4 photocatalyst;

[0038] The LabSolar 6A equipment was used to test Ni3ZnC 0.7 The photocatalytic effect of @C / g-C3N4 was tested. The specific test process included weighing 30mg of the composite photocatalyst and 15mL of isopropanol, placing them in a glass reaction container filled with 85mL of deionized water, and irradiating with light for 4 hours.

[0039] Figure 1 Ni3ZnC prepared in Example 1 0.7 X-ray diffraction analysis diagram of @C / g-C3N4, where the horizontal axis is the 2θ angle and the vertical axis is the diffraction peak intensity; 13° and 27° correspond to the (100) crystal plane and (002) crystal plane of g-C3N4 respectively, and Ni3ZnC 0.7 @C / g-C3N4 can also accurately correspond to Ni3ZnC 0.7 PDF#28-0713 and CPDF#26-1077, showing the successful preparation of Ni3ZnC 0.7 @C / g-C3N4 photocatalyst.

[0040] Figure 2 Ni3ZnC prepared in this comparative example 2 0.7 @C / g-C3N4 scanning image at 5μm. Among them, Ni3ZnC 0.7 @C presents a spherical nanoparticle structure and is evenly distributed on the g-C3N4 nanosheets.

[0041] Figure 3 Ni3ZnC prepared in Example 1 0.7 @C / g-C3N4 hydrogen evolution performance diagram. As shown in the figure, adding Ni3ZnC 0.7 After treatment with @C, the hydrogen evolution activity of g-C3N4 was significantly improved, with the hydrogen evolution amount reaching 643.075 μmol / g within four hours.

[0042] Example 2:

[0043] Step 1: urea and dicyandiamide are placed in a beaker containing a sulfuric acid solution in a mass ratio of 1:1, wherein the volume ratio of 1M concentrated sulfuric acid to ultrapure water is 1:2, and then stirred for 1 hour. Finally, the mixed solution is placed in a water bath and heated for 6 hours at 60°C. After the reaction is completed, the cooled reaction solution is poured out and centrifuged, and washed four times with deionized water and anhydrous ethanol respectively to obtain solid A;

[0044] 2 g of solid A was spread flatly in a porcelain boat and calcined in air at 600 °C for 2 h at a heating rate of 6 °C / min.

[0045] After calcination, the sample was cooled naturally in the furnace and ground in a mortar for 30 min to obtain yellow powder B, i.e., flaky g-C3N4;

[0046] Step 2: nickel chloride, zinc acetate, urea and acetylacetone were prepared in a molar ratio of 2:1:3:0.5, and then mixed with powder B in a ratio of 1:6 to obtain mixed powder C. 60 mL of ethylene glycol solution was added, wherein the volume ratio of ethylene glycol to ultrapure water was 1:5. The mixture was ultrasonicated for 60 minutes and then stirred on a magnetic stirrer for 120 minutes. The mixture was then quickly poured into the liner of a 150 mL reactor.

[0047] The operating temperature of the vacuum drying oven was set to 160°C. After the temperature in the drying oven rose to the set temperature, the sealed reactor was placed in the oven and kept warm for 10 hours. After the temperature in the oven dropped to room temperature, the reactor was taken out and cooled. The cooled reaction solution was poured out and centrifuged, and washed four times with deionized water and anhydrous ethanol respectively to obtain a precipitate. The precipitate was then placed in a vacuum drying oven and dried at 60°C for 15 hours to obtain solid D, i.e., NiZn-LDH / g-C3N4.

[0048] Step 3: Solid D and melamine were mixed at a mass ratio of 1:5 and ground in a mortar for 60 minutes to obtain powder E. Powder E was spread flat on a porcelain boat and placed in a tube furnace. The tube furnace was then evacuated to a vacuum state, and argon was slowly introduced. The operation was repeated three times until all the air in the tube furnace was exhausted. The tube furnace was then heated to 600°C at a rate of 10°C / min, and then kept warm for 2 hours. After the product was cooled, it was taken out and ground for 30 minutes to obtain powder F, i.e., Ni3ZnC 0.7 @C co-catalyst;

[0049] Step 4: First, mix powder F and powder B in a mass ratio of 0.6:5, then evacuate the tube furnace to a vacuum state, slowly introduce argon, and repeat the operation three times until all the air in the tube furnace is exhausted. Then, heat the tube furnace to 250°C at a rate of 2°C / min, and then keep it warm for 2 hours. After the product cools down, take it out to obtain Ni3ZnC 0.7 @C / g-C3N4 photocatalyst;

[0050] The LabSolar 6A equipment was used to test Ni3ZnC 0.7 The photocatalytic effect of @C / g-C3N4 was tested. The specific test process included weighing 30mg of the composite photocatalyst and 15mL of isopropanol, placing them in a glass reaction container filled with 85mL of deionized water, and irradiating with light for 4 hours.

[0051] Example 3:

[0052] Step 1: urea and dicyandiamide are placed in a beaker containing a sulfuric acid solution in a mass ratio of 2:3, wherein the volume ratio of 1M concentrated sulfuric acid to ultrapure water is 1:2, and then stirred for 2 hours. Finally, the mixed solution is placed in a water bath and heated for 3 hours at 80°C. After the reaction is completed, the cooled reaction solution is poured out and centrifuged, and washed five times with deionized water and anhydrous ethanol respectively to obtain solid A;

[0053] 3 g of solid A was spread flatly in a porcelain boat and calcined in air at 500 °C for 2 h at a heating rate of 2 °C / min.

[0054] After calcination, the sample was cooled naturally in the furnace and ground in a mortar for 60 min to obtain yellow powder B, i.e., flaky g-C3N4;

[0055] Step 2: Nickel chloride, zinc acetate, urea, and acetylacetone were prepared in a molar ratio of 3:2:4:0.6, and then mixed with powder B in a ratio of 1:4 to obtain mixed powder C. 50 mL of ethylene glycol solution was added, wherein the volume ratio of ethylene glycol to ultrapure water was 2:5. The mixture was ultrasonicated for 90 minutes and then stirred on a magnetic stirrer for 120 minutes. The mixture was then quickly poured into the liner of a 150 mL reactor.

[0056] The operating temperature of the vacuum drying oven was set to 140°C. After the temperature inside the drying oven reached the set temperature, the sealed reactor was placed in the oven and kept warm for 12 hours. After the temperature inside the oven dropped to room temperature, the reactor was removed and cooled. The cooled reaction solution was poured out and centrifuged, and then washed five times with deionized water and anhydrous ethanol respectively to obtain a precipitate. The precipitate was then placed in a vacuum drying oven and dried for 12 hours to obtain solid D, namely NiZn-LDH / g-C3N4;

[0057] Step 3: Solid D and melamine were mixed at a mass ratio of 2:5 and ground in a mortar for 60 minutes to obtain powder E. Powder E was spread flat on a porcelain boat and then placed in a tube furnace. The tube furnace was then evacuated to a vacuum state, and argon was slowly introduced. The operation was repeated three times until all the air in the tube furnace was exhausted. The tube furnace was then heated to 700°C at a rate of 10°C / min and then kept warm for 2 hours. After the product was cooled, it was taken out and ground for 30 minutes to obtain powder F, i.e., Ni3ZnC 0.7 @C co-catalyst;

[0058] Step 4: First, mix powder F and powder B in a mass ratio of 1:5, then evacuate the tube furnace to a vacuum state, slowly introduce argon, and repeat the operation three times until all the air in the tube furnace is exhausted. Then, heat the tube furnace to 400°C at a rate of 5°C / min, and then keep it warm for 2 hours. After the product cools down, take it out to obtain Ni3ZnC 0.7@C / g-C3N4 photocatalyst;

[0059] The LabSolar 6A equipment was used to test Ni3ZnC 0.7 The photocatalytic effect of @C / g-C3N4 was tested. The specific test process included weighing 30mg of the composite photocatalyst and 15mL of isopropanol, placing them in a glass reaction container filled with 85mL of deionized water, and irradiating with light for 4 hours.

[0060] Example 4:

[0061] Step 1: Urea and dicyandiamide are placed in a beaker containing a sulfuric acid solution in a mass ratio of 5:1, wherein the volume ratio of 1M concentrated sulfuric acid to ultrapure water is 2:5, and then stirred for 3 hours. Finally, the mixed solution is placed in a water bath and heated for 1 hour at 80°C. After the reaction is completed, the cooled reaction solution is poured out and centrifuged, and washed five times with deionized water and anhydrous ethanol respectively to obtain solid A;

[0062] 3 g of solid A was spread flatly in a porcelain boat and calcined in air at 450°C for 1 h at a heating rate of 10°C / min.

[0063] After calcination, the sample was naturally cooled in the furnace and ground in a mortar for 120 min to obtain yellow powder B, i.e., flaky g-C3N4;

[0064] Step 2: Nickel chloride, zinc acetate, urea, and acetylacetone were prepared in a molar ratio of 1:1.5:1:0.1, and then mixed with powder B in a ratio of 1:1 to obtain mixed powder C. 50 mL of ethylene glycol solution was added, wherein the volume ratio of ethylene glycol to ultrapure water was 1.5:4. The mixture was ultrasonicated for 30 minutes and then stirred on a magnetic stirrer for 60 minutes. The mixture was then quickly poured into the liner of a 150 mL reactor.

[0065] The operating temperature of the vacuum drying oven was set to 100°C. After the temperature inside the drying oven reached the set temperature, the sealed reactor was placed in the oven and kept warm for 16 hours. After the temperature inside the oven dropped to room temperature, the reactor was removed and cooled. The cooled reaction solution was poured out and centrifuged, and then washed five times with deionized water and anhydrous ethanol respectively to obtain a precipitate. The precipitate was then placed in a vacuum drying oven at 60°C and dried for 20 hours to obtain solid D, namely NiZn-LDH / g-C3N4.

[0066] Step 3: Solid D and melamine were mixed at a mass ratio of 0.5:10 and ground in a mortar for 120 minutes to obtain powder E. Powder E was spread flat on a porcelain boat and placed in a tube furnace. The tube furnace was then evacuated to a vacuum state, and argon was slowly introduced. The operation was repeated three times until all the air in the tube furnace was exhausted. The tube furnace was then heated to 650°C at a heating rate of 5°C / min, and then kept warm for 3 hours. After the product was cooled, it was taken out and ground for 60 minutes to obtain powder F, i.e., Ni3ZnC 0.7 @C co-catalyst;

[0067] Step 4: First, mix powder F and powder B in a mass ratio of 0.5:10, then evacuate the tube furnace to a vacuum state, slowly introduce argon, and repeat the operation three times until all the air in the tube furnace is exhausted. Then, heat the tube furnace to 200°C at a rate of 3°C / min, and then keep it warm for 1 hour. After the product cools down, take it out to obtain Ni3ZnC 0.7 @C / g-C3N4 photocatalyst;

[0068] The LabSolar 6A equipment was used to test Ni3ZnC 0.7 The photocatalytic effect of @C / g-C3N4 was tested. The specific test process included weighing 30mg of the composite photocatalyst and 15mL of isopropanol, placing them in a glass reaction container filled with 85mL of deionized water, and irradiating with light for 4 hours.

[0069] Example 5:

[0070] Step 1: Urea and dicyandiamide are placed in a beaker containing sulfuric acid solution in a mass ratio of 3:2, wherein the volume ratio of 1M concentrated sulfuric acid to ultrapure water is 1.5:2, and then stirred for 2 hours. Finally, the mixed solution is placed in a water bath and heated for 3 hours at 80°C. After the reaction is completed, the cooled reaction solution is poured out and centrifuged, and washed five times with deionized water and anhydrous ethanol respectively to obtain solid A;

[0071] 3 g of solid A was spread flatly in a porcelain boat and calcined in air at 450°C for 1 h at a heating rate of 10°C / min.

[0072] After calcination, the sample was cooled naturally in the furnace and ground in a mortar for 80 min to obtain yellow powder B, i.e., flaky g-C3N4;

[0073] Step 2: Nickel chloride, zinc acetate, urea, and acetylacetone were prepared in a molar ratio of 3:1:5:0.2, and then mixed with powder B in a ratio of 1:3 to obtain mixed powder C. 50 mL of ethylene glycol solution was added, wherein the volume ratio of ethylene glycol to ultrapure water was 1:3. The mixture was ultrasonicated for 90 minutes and then stirred on a magnetic stirrer for 150 minutes. The mixture was then quickly poured into the liner of a 150 mL reactor.

[0074] The operating temperature of the vacuum drying oven was set to 120°C. After the temperature inside the drying oven reached the set temperature, the sealed reactor was placed in the oven and kept warm for 12 hours. After the temperature inside the oven dropped to room temperature, the reactor was removed and cooled. The cooled reaction solution was poured out and centrifuged, and then washed five times with deionized water and anhydrous ethanol respectively to obtain a precipitate. The precipitate was then placed in a vacuum drying oven at 80°C for 12 hours to obtain solid D, namely NiZn-LDH / g-C3N4;

[0075] Step 3: Solid D and melamine were mixed at a mass ratio of 4:1 and ground in a mortar for 30 minutes to obtain powder E. Powder E was spread flat on a porcelain boat and placed in a tube furnace. The tube furnace was then evacuated to a vacuum state, and argon was slowly introduced. The operation was repeated three times until all the air in the tube furnace was exhausted. The tube furnace was then heated to 650°C at a heating rate of 7°C / min, and then kept warm for 4 hours. After the product was cooled, it was taken out and ground for 30 minutes to obtain powder F, i.e., Ni3ZnC 0.7 @C co-catalyst;

[0076] Step 4: First, mix powder F and powder B in a mass ratio of 1:8, then evacuate the tube furnace to a vacuum state, slowly introduce argon, and repeat the operation three times until all the air in the tube furnace is exhausted. Then, heat the tube furnace to 350°C at a rate of 4°C / min, and then keep it warm for 3 hours. After the product cools down, take it out to obtain Ni3ZnC 0.7 @C / g-C3N4 photocatalyst;

[0077] The LabSolar 6A equipment was used to test Ni3ZnC 0.7 The photocatalytic effect of @C / g-C3N4 was tested. The specific test process included weighing 30mg of the composite photocatalyst and 15mL of isopropanol, placing them in a glass reaction container filled with 85mL of deionized water, and irradiating with light for 4 hours.

[0078] The above specific embodiments are merely examples selected to clearly illustrate the effects achievable by the present invention and should not be considered to be the complete set of embodiments of the present invention. Practitioners in the relevant field will appreciate that other variations can be made based on the above descriptions, which are not exhaustive here. Any numerical changes derived from the design principles of the present invention remain within the scope of protection of the claims.

Claims

1. A Ni3ZnC 0.7 The preparation method of @C / g-C3N4 photocatalyst is characterized in that: The following steps are involved: Step 1: Prepare nanosheet g-C3N4 by a one-step calcination method; Step 2: nickel chloride, zinc acetate, urea and acetylacetone are mixed in a molar ratio of (1-3): (1-2): (1-5): (0.1-0.6) to obtain a mixed powder, and then the mixed powder and the nano-sheet g-C3N4 prepared in step 1 are mixed in a mass ratio of 1: (1-6), water and ethylene glycol mixture are added, ultrasonic treatment is performed, and then stirring is performed until uniform dispersion is obtained, and then the mixture is poured into the lining of the reactor, placed in a vacuum drying oven at 100-160 ° C for 10-16 hours, and after the temperature in the oven drops to room temperature, the reactor is taken out, centrifuged, washed, and dried to obtain NiZn-LDH / g-C3N4; Step 3: Mix the NiZn-LDH / g-C3N4 prepared in step 2 with melamine in a mass ratio of (0.5-4): (1-10), grind and spread on a porcelain boat and then place it in a tube furnace. Under an argon atmosphere, heat the tube furnace at a rate of 5-10°C / min to 500-700°C, keep warm for 2-4h, and after the product is cooled, take out and grind to obtain Ni3ZnC 0.7 @C co-catalyst; Step 4: First, the Ni3ZnC prepared in step 3 0.7 The @C co-catalyst and the nano-sheet g-C3N4 prepared in step 1 are mixed in a mass ratio of (0.5-1): (5-10) and placed in a tube furnace. The tube furnace is heated to 200-400°C at a rate of 2-5°C / min under an argon atmosphere and kept warm for 1-3 hours. After the product is cooled, it is taken out to obtain Ni3ZnC 0.7 @C / g-C3N4 photocatalyst.

2. Ni3ZnC according to claim 1 0.7 The preparation method of @C / g-C3N4 photocatalyst is characterized in that: The specific steps of preparing nano-sheet g-C3N4 by the one-step calcination method described in step 1 include: Urea and dicyandiamide are sequentially added to a beaker containing a sulfuric acid solution in a mass ratio of (1-5):(1-3), and stirred for 1-3 hours. Finally, the mixed solution is heated in a water bath at a temperature of 60-80°C for 1-6 hours. After the reaction is completed, the cooled reaction solution is poured out, centrifuged, and washed to obtain solid A. The volume ratio of 1M concentrated sulfuric acid to ultrapure water in the sulfuric acid solution is (1-2):(2-5); Solid A is spread flat on a porcelain boat, placed in a tube furnace under air atmosphere, heated to 450-600°C at a rate of 2-10°C / min, and kept warm for 1-4 hours. After calcination, the sample is naturally cooled in the furnace and ground to obtain yellow powder B, i.e., flaky g-C3N4.

3. Ni3ZnC according to claim 1 0.7 The preparation method of @C / g-C3N4 photocatalyst is characterized in that: The volume ratio of ethylene glycol to ultrapure water in the water and ethylene glycol mixture described in step 2 is (1-2):(3-5).

4. Ni3ZnC according to claim 1 0.7 The preparation method of @C / g-C3N4 photocatalyst is characterized in that: The ultrasonic treatment time in step 2 is 30-120 min.

5. Ni3ZnC according to claim 1 0.7 The preparation method of @C / g-C3N4 photocatalyst is characterized in that: The stirring in step 2 is performed by placing the mixture on a magnetic stirrer and stirring for 60-150 minutes.

6. Ni3ZnC according to claim 1 or 2 0.7 The preparation method of @C / g-C3N4 photocatalyst is characterized in that: The washing is performed by washing with deionized water and anhydrous ethanol for 3-5 times respectively.

7. Ni3ZnC according to claim 1 0.7 The preparation method of @C / g-C3N4 photocatalyst is characterized in that: The drying step in step 2 is performed in a vacuum drying oven for 10-20 hours.

8. Ni3ZnC according to claim 1 or 2 0.7 The preparation method of @C / g-C3N4 photocatalyst is characterized in that: The grinding step is to place the mixture in a mortar and grind it for 30-120 minutes.

9. Ni3ZnC prepared by the method according to any one of claims 1 to 8 0.7 @C / g-C3N4 photocatalyst.

10. Ni3ZnC as claimed in claim 9 0.7 Application of @C / g-C3N4 photocatalyst in photocatalytic hydrogen production.

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