A high-activity ZnTCPP / NiFeB photocatalytic nitrogen fixer and its preparation method and application

Abstract

The present invention discloses a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer, its preparation method, and application, belonging to the field of photocatalytic technology. The preparation method of the highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps: adding NiFeB hydroxide nanosheets, pyrazine, zinc nitrate, polyvinyl pyrrolidone, and tetra-p-carboxyphenylporphyrin to an organic solvent, performing a reflux reaction, washing, and drying to obtain the highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer. The present invention utilizes NiFeB to promote the construction of a highly active nitrogen fixation center, promotes the activation and conversion of nitrogen by in-situ growth of NiFeB nanosheets on ZnTCPP, effectively improving the photocatalytic activity and the nitrogen fixation effect. The present invention introduces electron-deficient B into the traditional NiFe hydroxide catalyst, effectively promoting the oxidation state transition of Ni, thereby significantly improving the nitrogen fixation activity of the catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysis, and in particular to a high-activity ZnTCPP / NiFeB photocatalytic nitrogen fixer, a preparation method thereof, and an application thereof. Background Art

[0002] Since the 21st century, with the rapid development of modern industry, energy crises and environmental pollution have become increasingly prominent. Photocatalytic nitrogen fixation technology has the advantages of mild reaction conditions and the ability to directly utilize solar energy, and is considered a green, clean, and efficient ammonia synthesis process. Porphyrin, as a common organic light-harvesting unit, has strong absorption in the visible light region: the Soret absorption band is at 400-500nm, and the Q absorption band is at 500-700nm. It is chemically stable, easy to synthesize and modify, and has ultrafast electron injection and a long triplet lifetime. It is widely used as an artificial photosensitizer and photocatalyst to simulate the solar energy conversion process in natural photosynthetic reactions. In addition, the hydrogen on the central nitrogen atom is easily replaced by metal ions to form metalloporphyrins; at the same time, different porphyrin derivatives can be obtained by introducing different functional groups to replace the hydrogen on the peripheral methylene groups. The functionalized porphyrin has excellent photoelectric properties, a large molar absorption coefficient and visible light response, and the ability to separate photogenerated electrons and holes. It can be compounded with semiconductor catalysts or used to prepare MOFs, and has broad application prospects in photocatalytic water decomposition, CO2 reduction, selective organic synthesis, etc.

[0003] People have been committed to developing catalysts for nitrogen fixation. In the process of nitrogen fixation, transition metals (such as Ni 2+ ) can be converted into high oxidation state species, which are considered to be the active centers of the reaction. Therefore, promoting the formation of the desired high oxidation state transition metal species may increase the reaction rate. Therefore, the introduction of electron-deficient B into the traditional NiFe hydroxide catalyst can effectively promote the oxidation state conversion of Ni, thereby significantly improving the nitrogen fixation activity of the catalyst. Directly from Ni 2+ extract electrons to form the desired Ni 3+δ This is a difficult process, and the B near nickel may participate in the oxidation of nickel by acting as a transit point for the flow of electrons involved in this process. Due to its inherent electron deficiency, the transition B site may play the role of an electron sink, promoting the electrons from Ni to Ni. 2+ bit mobility, thereby allowing the formation of highly active Ni at reduced potentials 3+δ . Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a high-activity ZnTCPP / NiFeB photocatalytic nitrogen fixer and its preparation method and application. The high-activity ZnTCPP / NiFeB photocatalytic nitrogen fixer has excellent photocatalytic performance and excellent nitrogen fixation effect.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0007] NiFeB hydroxide nanosheets, pyrazine, zinc nitrate, polyvinyl pyrrolidone and tetra-p-carboxyphenyl porphyrin are added to an organic solvent, refluxed, washed and dried to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0008] The present invention creatively adopts NiFeB to promote the construction of highly active nitrogen fixation centers, promotes the activation and conversion of nitrogen by in-situ growing NiFeB nanosheets on ZnTCPP, effectively improves the photocatalytic activity and enhances the nitrogen fixation effect.

[0009] The present invention introduces electron-deficient B into a traditional NiFe hydroxide catalyst, effectively promoting the oxidation state conversion of Ni, thereby significantly improving the nitrogen fixation activity of the catalyst.

[0010] As a preferred embodiment of the present invention, the mass ratio of the NiFeB hydroxide nanosheets, pyrazine, zinc nitrate, and tetra-p-carboxyphenylporphyrin is (0.2-0.8): (6-10): (40-50): (30-50).

[0011] As a preferred embodiment of the present invention, the mass ratio of the NiFeB hydroxide nanosheets to polyvinyl pyrrolidone is (0.2-0.8): (100-300).

[0012] It should be noted that the amount of the organic solvent is not limited in the present invention.

[0013] Exemplarily, the solid-liquid ratio of NiFeB hydroxide nanosheets to the organic solvent is (0.2-0.8) g: (10-100) mL.

[0014] As a preferred embodiment of the present invention, the mass ratio of the NiFeB hydroxide nanosheets, pyrazine, zinc nitrate, and tetracarboxyphenylporphyrin is (0.2-0.8):8:45:40. When the amounts of the raw materials are within this range, the photocatalytic activity and nitrogen fixation effect are better.

[0015] As a preferred embodiment of the present invention, the mass ratio of the NiFeB hydroxide nanosheets, pyrazine, zinc nitrate, and tetra(p-carboxyphenyl)porphyrin is 0.4:8:45:40. When the amounts of the raw materials are within this range, photocatalytic activity is optimal, significantly improving both photocatalytic activity and nitrogen fixation.

[0016] As a preferred embodiment of the present invention, the organic solvent includes at least one of methanol, ethanol, propanol, butanol, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, sulfolane, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene nitrate, ethylene carbonate, acetone, 1,4-butyrolactone and dimethylacetamide.

[0017] As a preferred embodiment of the present invention, the method for preparing NiFeB hydroxide nanosheets comprises the following steps:

[0018] Adding nickel chloride hexahydrate solution and ferric chloride hexahydrate solution to a solvent, uniformly dispersing them, adding sodium borohydride solution, ultrasonically treating, washing, and drying to obtain NiFeB alloy nanoparticles;

[0019] NiFeB alloy nanoparticles are added to potassium hydroxide solution, ultrasonicated, centrifuged and dried to obtain alloy nanoparticles.

[0020] As a preferred embodiment of the present invention, the molar concentration of the nickel chloride hexahydrate solution is 0.1-0.2 mol / L.

[0021] As a preferred embodiment of the present invention, the molar concentration of the ferric chloride hexahydrate solution is 0.01 to 0.1 mol / L.

[0022] As a preferred embodiment of the present invention, the molar concentration of the sodium borohydride solution is 0.1 to 1 mol / L.

[0023] As a preferred embodiment of the present invention, the molar concentration of the potassium hydroxide solution is 0.5 to 2 mol / L.

[0024] As a preferred embodiment of the present invention, the volume ratio of the nickel chloride hexahydrate solution, the ferric chloride hexahydrate solution, the sodium borohydride solution, and the potassium hydroxide solution is (7-8): (6-7): (5-20): (100-1000).

[0025] The present invention also provides a high-activity ZnTCPP / NiFeB photocatalytic nitrogen fixer, which is prepared by the above-mentioned preparation method.

[0026] The present invention also provides an application of a high-activity ZnTCPP / NiFeB photocatalytic nitrogen fixer as a photoreduction nitrogen fixation catalyst.

[0027] The beneficial effects of the present invention are as follows: (1) The present invention uses NiFeB to promote the construction of highly active nitrogen-fixing centers. By in situ growing NiFeB nanosheets on ZnTCPP, the activation and conversion of nitrogen are promoted, effectively improving the photocatalytic activity and the nitrogen-fixing effect. (2) The present invention introduces electron-deficient B into the traditional NiFe hydroxide catalyst, effectively promoting the oxidation state transformation of Ni, thereby significantly improving the nitrogen-fixing activity of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 These are the XRD patterns of ZnTCPP, NiFeB and ZnTCPP / NiFeB samples.

[0029] Figure 2 These are the FT-IR curves of ZnTCPP, NiFeB and ZnTCPP / NiFeB samples.

[0030] Figure 3 This is the Raman spectrum of NiFeB.

[0031] Figure 4 UV-vis DRS spectra of ZnTCPP, NiFeB and ZnTCPP / NiFeB samples

[0032] Figure 5 This is the detection diagram of active oxygen species of ZnTCPP / NiFeB

[0033] Figure 6 These are the photocurrent density curves and EIS spectra of ZnTCPP, NiFeB and ZnTCPP / NiFeB.

[0034] Figure 7 The photocatalytic nitrogen fixation performance of ZnTCPP, NiFeB and ZnTCPP / NiFeB was compared under 300W xenon lamp irradiation. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0037] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0038] In the present application, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0039] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0040] Example 1

[0041] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0042] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. After centrifugation and drying, NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH) were obtained.

[0043] (2) 0.4 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer (abbreviated as ZT-NFB-1%).

[0044] Example 2

[0045] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0046] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles. The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. The mixture was then centrifuged and dried to obtain NiFeB hydroxide nanosheets.

[0047] (2) 0.2 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer (abbreviated as ZT-NFB-0.5%).

[0048] Example 3

[0049] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0050] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles. The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. The mixture was then centrifuged and dried to obtain NiFeB hydroxide nanosheets.

[0051] (2) 0.8 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer (abbreviated as ZT-NFB-2%).

[0052] Example 4

[0053] A method for preparing ZnTCPP comprises the following steps:

[0054] 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80 °C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain ZnTCPP.

[0055] Example 5

[0056] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0057] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. After centrifugation and drying, NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH) were obtained.

[0058] (2) 0.4 mg of NiFeB hydroxide nanosheets obtained in step (1), 6 mg of pyrazine, 40 mg of Zn(NO3)2, 100 mg of PVP and 30 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0059] Example 6

[0060] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0061] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. After centrifugation and drying, NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH) were obtained.

[0062] (2) 0.4 mg of NiFeB hydroxide nanosheets obtained in step (1), 10 mg of pyrazine, 50 mg of Zn(NO3)2, 300 mg of PVP and 50 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0063] Example 7

[0064] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0065] (1) 700 μL of 0.14 M NiCl2·6H2O solution and 600 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 0.5 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 10 mL of KOH (1 M) solution and ultrasonically treated. The mixture was centrifuged and dried to obtain NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH).

[0066] (2) 0.4 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0067] Example 8

[0068] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0069] (1) 800 μL of 0.14 M NiCl2·6H2O solution and 700 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 2 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 100 mL of KOH (1 M) solution and ultrasonically treated. After centrifugation and drying, NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH) were obtained.

[0070] (2) 0.4 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0071] Comparative Example 1

[0072] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0073] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. After centrifugation and drying, NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH) were obtained.

[0074] (2) 0.8 mg of NiFeB hydroxide nanosheets obtained in step (1), 5.5 mg of pyrazine, 30 mg of Zn(NO3)2, 200 mg of PVP and 20 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0075] Comparative Example 2

[0076] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0077] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. After centrifugation and drying, NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH) were obtained.

[0078] (2) 0.8 mg of NiFeB hydroxide nanosheets obtained in step (1), 11.5 mg of pyrazine, 60 mg of Zn(NO3)2, 200 mg of PVP and 70 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0079] Comparative Example 3

[0080] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0081] (1) 600 μL of 0.14 M NiCl2·6H2O solution and 600 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 3 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. The mixture was centrifuged and dried to obtain NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH).

[0082] (2) 0.8 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0083] Comparative Example 4

[0084] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0085] (1) 900 μL of 0.14 M NiCl2·6H2O solution and 800 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 3 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. The mixture was centrifuged and dried to obtain NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH).

[0086] (2) 0.8 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0087] Comparative Example 5

[0088] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0089] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. After centrifugation and drying, NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH) were obtained.

[0090] (2) 0.1 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0091] Comparative Example 6

[0092] A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer comprises the following steps:

[0093] (1) 727 μL of 0.14 M NiCl2·6H2O solution and 673 μL of 0.05 M FeCl3·6H2O solution were dissolved in 10 mL of ethanol and ultrasonically treated for 5 min. Then, 1 mL of 0.5 M NaBH4 aqueous solution was added dropwise to the above solution. The mixture was ultrasonically treated for 45 min, washed by centrifugation with ethanol, and dried to obtain NiFeB alloy nanoparticles (abbreviated as NiFeB). The above NiFeB alloy nanoparticles were added to 50 mL of KOH (1 M) solution and ultrasonically treated. After centrifugation and drying, NiFeB hydroxide nanosheets (abbreviated as NiFeB-LDH) were obtained.

[0094] (2) 1 mg of NiFeB hydroxide nanosheets obtained in step (1), 8 mg of pyrazine, 45 mg of Zn(NO3)2, 200 mg of PVP and 40 mg of TCPP were dispersed in 60 mL of a mixed solution of DMF:ethanol = 3:1 (v:v), refluxed at 80°C in an oil bath for 16 h, and then the product was washed with anhydrous ethanol and DMF to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer.

[0095] Test Case

[0096] 1. Figure 1 The phase structures of the prepared samples (NiFeB, ZnTCPP, ZT-NFB-1%, ZT-NFB-0.5%, and ZT-NFB-2% of Example 1) were confirmed by X-ray diffraction analysis. Figure 1 The X-ray diffraction patterns of ZnTCPP, NiFeB and ZnTCPP / NiFeB (ie, ZT-NFB) are shown.

[0097] Pure ZnTCPP and all prepared composites (i.e., ZT-NFB-1%, ZT-NFB-0.5%, and ZT-NFB-2%) exhibit strong peaks at 2θ = 7.6° and 21.5°, corresponding to the (100) and (004) crystal planes of ZnTCPP, respectively. For pure NiFeB, a distinct diffraction peak at ~34° (2θ) corresponds to the 100 face of the coedge-joined MO6 (M = Ni, Fe) octahedron in the metal hydroxide.

[0098] Further FT-IR analysis confirmed the fine structure of the material. Figure 2 As shown in a, for pure ZnTCPP, at 1710 cm -1 Strong C=O bond vibration was observed near 1415 cm -1 The COO-bond is observed near 995 cm-1. In addition, the Zn-N bond in the metalloporphyrin is located at 995 cm-1. -1 For NiFeB, such as Figure 2 b, 1280 and 975 cm -1 The bands at 1000 cm-1 can be attributed to BO stretching and bending vibrations, respectively. -1 The following bands can be attributed to the stretching vibrations of metal-oxygen (Ni-O and Fe-O) and metal-oxygen-metal (Ni-O-Fe). The characteristic peaks of NiFeB and ZnTCPP can be observed on the sample ZnTCPP / NiFeB, indicating the formation of a hybrid heterostructure. In addition, the Raman analysis results ( Figure 3 ) at 340cm -1 The vibration peak of BO can be clearly observed at , which further confirms the formation of ZnTCPP / NiFeB nanocomposite materials.

[0099] 2. The light absorption capacity of the samples was evaluated using UV-Vis diffuse reflectance spectroscopy. Figure 4 As shown in a, the NiFeB sample has obvious absorption at 300-800nm. Due to the characteristic absorption of porphyrin compounds in the ultraviolet-visible light region, pure ZnTCPP has obvious strong absorption peaks at 200-800nm. The strong absorption peak near 400-500nm is the Soret band, and several absorption peaks in the range of 500-700nm can be attributed to the Q band. Compared with pure NiFeB and ZnTCPP, the absorption spectrum of the composite materials (ZT-NFB-1%, ZT-NFB-0.5%, ZT-NFB-2%) has obvious enhancement in the entire visible light region, which also shows that the composite of the two-phase materials produces a significant synergistic effect, greatly enhances the light absorption efficiency, and is beneficial to the subsequent photocatalytic reaction. The band gap of the prepared sample was estimated using the Kubelka-Munk equation. The results are shown in Figure 4As shown in (b), the Eg of ZnTCPP and NiFeB are 1.64eV and 2.83eV, respectively. Compared with NiFeB and ZnTCPP, the absorption of the composite sample is significantly enhanced in the entire area, which is very beneficial for the subsequent photocatalytic reaction.

[0100] Figure 5 The electron paramagnetic resonance (EPR) spectrum is shown, e.g. Figure 5 As shown in (ac), no ROS signals were detected in either the Zn-TCPP or the composite sample under dark conditions. However, under illumination, strong ROS peaks appeared. These results demonstrate the formation of a heterojunction and the excellent separation of photogenerated electrons and holes. This charge transfer effectively promotes the oxidation of nitrogen.

[0101] 3. Electrochemical impedance spectroscopy (EIS) is an effective tool for analyzing the charge transfer and recombination processes of photocatalysts. The smaller the radius of curvature of the curve, the smaller the impedance and the faster the electron transfer, which represents a high catalytic efficiency. Figure 6 a is the impedance test result of NiFeB and ZnTCPP. It can be observed that the curvature of the composite sample is significantly smaller than that of the NiFeB and ZnTCPP samples. This may be because after the flake ZnTCPP is compounded with NiFeB, the ordered layered stacking accelerates the charge transfer at the interface, reduces the obstacle of electron conduction, and promotes the separation and conduction of carriers. In addition, Figure 6 As shown in (b), the composite photocatalyst exhibits the highest photocurrent density, which means that the separation and transfer of photogenerated electrons and holes are most efficient.

[0102] The photocatalytic performance of all samples was tested under full-spectrum xenon lamp irradiation for 3 h. Figure 7 The nitrogen oxidation activity of ZnTCPP / NiFeB composite materials with different NiFeB loadings is shown in Table 1. The nitrogen oxidation activity of the examples and comparative examples is shown in Table 1. Pure ZnTCPP has lower NO 3- (278.23 μmol·g -1 ·h -1 ) photocatalytic activity. The ZnTCPP / NiFeB catalyst with 1% NiFeB loading has the highest activity, NO 3- The yield was 689.35 μmol·g -1 ·h -1 , which is 2.5 times that of ZnTCPP. The results show that in the presence of NiFeB, the nitrogen oxidation activity of ZnTCPP / NiFeB composite material is significantly improved.

[0103] Table 1

[0104]

[0105]

[0106] It can be seen from Table 1 that the ZnTCPP / NiFeB photocatalytic nitrogen fixer of the present invention has excellent photocatalytic performance and excellent nitrogen fixation effect.

[0107] By comparing Example 3 with Comparative Examples 1 to 2, it can be seen that the amount of pyrazine, Zn(NO3)2 and TCPP used has a certain influence on the effect. By controlling the mass ratio of pyrazine, Zn(NO3)2 and TCPP within the range of the present invention, the photocatalytic activity is further improved and the nitrogen fixation effect is improved.

[0108] By comparing Example 3 with Comparative Examples 3 to 4, it can be seen that the volume ratio of nickel chloride hexahydrate solution, ferric chloride hexahydrate solution, and sodium borohydride solution has a certain influence on the effect. By adjusting the volume ratio of nickel chloride hydrate solution, ferric chloride hexahydrate solution, and sodium borohydride solution within the range of the present invention, the photocatalytic activity is further improved and the nitrogen fixation effect is improved.

[0109] By comparing Examples 1 to 3 with Comparative Examples 5 to 6, it can be seen that the amount of NiFeB hydroxide nanosheets has a significant influence on the effect. By controlling the amount of NiFeB hydroxide nanosheets within the range of the present invention, the photocatalytic activity is significantly improved, and the nitrogen fixation effect is improved. In particular, when the amount of NiFeB hydroxide nanosheets is within the range of Example 1, the photocatalytic activity is significantly improved, and the nitrogen fixation effect is more significantly improved.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer, characterized in that: The following steps are involved: NiFeB hydroxide nanosheets, pyrazine, zinc nitrate, polyvinyl pyrrolidone and tetracarboxyphenyl porphyrin are added to an organic solvent, refluxed, washed and dried to obtain a highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer; the mass ratio of the NiFeB hydroxide nanosheets, pyrazine, zinc nitrate and tetracarboxyphenyl porphyrin is (0.2-0.8): (6-10): (40-50): (30-50); The method for preparing NiFeB hydroxide nanosheets comprises the following steps: adding nickel chloride hexahydrate solution and ferric chloride hexahydrate solution to a solvent, dispersing them uniformly, adding sodium borohydride solution, ultrasonically treating, washing, and drying to obtain NiFeB alloy nanoparticles; adding the NiFeB alloy nanoparticles to a potassium hydroxide solution, ultrasonically treating, centrifuging, and drying to obtain NiFeB hydroxide nanosheets; The molar concentration of the nickel chloride hexahydrate solution is 0.1 to 0.2 mol / L; the molar concentration of the ferric chloride hexahydrate solution is 0.01 to 0.1 mol / L; the molar concentration of the sodium borohydride solution is 0.1 to 1 mol / L; and the molar concentration of the potassium hydroxide solution is 0.5 to 2 mol / L. The volume ratio of the nickel chloride hexahydrate solution, the ferric chloride hexahydrate solution, the sodium borohydride solution, and the potassium hydroxide solution is (7-8): (6-7): (5-20): (100-1000).

2. The method for preparing the highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer according to claim 1, characterized in that: The mass ratio of the NiFeB hydroxide nanosheets to polyvinyl pyrrolidone is (0.2-0.8): (100-300).

3. The method for preparing the highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer according to claim 1, characterized in that: The mass ratio of the NiFeB hydroxide nanosheets, pyrazine, zinc nitrate, and tetra-p-carboxyphenyl porphyrin is (0.2-0.8):8:45:

40.

4. The method for preparing the highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer according to claim 1, characterized in that: The mass ratio of the NiFeB hydroxide nanosheets, pyrazine, zinc nitrate and tetra-p-carboxyphenylporphyrin is 0.4:8:45:

40.

5. The method for preparing the highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer according to claim 1, characterized in that: The organic solvent includes at least one of methanol, ethanol, propanol, butanol, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, sulfolane, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene nitrate, ethylene carbonate, acetone, 1,4-butyrolactone and dimethylacetamide.

6. A highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the highly active ZnTCPP / NiFeB photocatalytic nitrogen fixer according to claim 6 as a photoreduction nitrogen fixation catalyst.

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