Nitrogen and phosphorus co-doped carbon catalyst as well as preparation method and application thereof

Abstract

The invention provides a nitrogen-phosphorus co-doped carbon catalyst and a preparation method and application thereof, and belongs to the technical field of electric energy catalytic conversion. The method comprises the following steps: adding polyether F127, hexamethylenetetramine, phytic acid and 1, 3, 5-trimethylbenzene into a solution containing 3-aminophenol, and uniformly stirring to obtain a mixed solution; performing hydrothermal reaction on the mixed solution to obtain a reaction product; and calcining the reaction product to obtain the nitrogen and phosphorus co-doped carbon catalyst. The nitrogen-phosphorus co-doped carbon catalyst with mesoporous structures uniformly and orderly distributed on a solid sphere is prepared, the doping level of pyridine N is regulated and controlled through P doping, the content of pyridine nitrogen is increased, meanwhile, uniform and ordered mesopores are formed in the whole sphere, a developed pore structure is formed, exposed catalytic active sites are increased, and the catalytic activity of the catalyst is improved. And the directional adsorption of carbon dioxide is facilitated, so that the catalytic activity of the material is greatly improved, and the high-selectivity production of CO can be realized at lower overpotential.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic conversion technology, specifically to a nitrogen-phosphorus co-doped carbon catalyst, its preparation method, and its application. Background Technology

[0002] For a considerable period, human societal development relied primarily on fossil fuels such as coal, oil, and natural gas, inevitably leading to increasingly severe resource shortages and the greenhouse effect. To address the ever-increasing carbon dioxide emissions and achieve the 1.5 °C target for mitigating global warming stipulated in the Paris Agreement, converting carbon dioxide into usable chemical resources and reintroducing it into the carbon cycle through specific technologies is a crucial step towards achieving carbon neutrality.

[0003] Electrocatalytic CO2 reduction is considered an environmentally friendly and efficient method to reduce atmospheric CO2 concentration and convert it into valuable fuels and chemicals. However, due to the slow kinetics of the CO2 reduction reaction (CO2RR) and the unavoidable hydrogen evolution competition reaction in aqueous solutions, the conversion of CO2 into fuels using electrocatalytic processes still faces significant technical challenges. Therefore, developing low-cost, efficient, and stable CO2 reduction electrocatalysts is of great importance. Since N-atom modification breaks the electroneutrality of C atoms, metal-free nitrogen-carbon (NC) materials have shown good CO2RR catalytic activity as a new generation of catalysts. However, at lower overpotentials, NC materials still suffer from poor selectivity and activity for single products. Summary of the Invention

[0004] In view of the technical problems existing in the background art, this application provides a nitrogen-phosphorus co-doped carbon catalyst, its preparation method and application, aiming to solve the technical problem of poor selectivity of existing NC materials at low overpotentials.

[0005] In a first aspect, embodiments of this application provide a method for preparing a nitrogen-phosphorus co-doped carbon catalyst, comprising the following steps: Add polyether F127, hexamethylenetetramine, phytic acid and 1,3,5-trimethylbenzene to a solution containing 3-aminophenol, stir until homogeneous, and obtain a mixed solution; The mixed solution was subjected to a hydrothermal reaction to obtain the reaction product; The reaction product was calcined to obtain a nitrogen-phosphorus co-doped carbon catalyst.

[0006] Optionally, in some embodiments of this application, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene are added sequentially to a solution containing 3-aminophenol.

[0007] Optionally, in some embodiments of this application, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene are added to a solution containing 3-aminophenol at a rotation speed of 600-800 rpm.

[0008] Optionally, in some embodiments of this application, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene are added to a solution containing 3-aminophenol within a time range of 1 to 10 minutes.

[0009] Optionally, in some embodiments of this application, the mixed solution is a homogeneous micelle solution.

[0010] Optionally, in some embodiments of this application, the mass ratio of polyether F127 to 3-aminophenol is 2 to 0.5:1.

[0011] Optionally, in some embodiments of this application, the mass ratio of hexamethylenetetramine to 3-aminophenol is 1 to 3:1.

[0012] Optionally, in some embodiments of this application, the mass ratio of phytic acid to 3-aminophenol is 1 to 3:1.

[0013] Optionally, in some embodiments of this application, the mass ratio of 1,3,5-trimethylbenzene to 3-aminophenol is 0.2 to 3:11.

[0014] Optionally, in some embodiments of this application, the temperature of the hydrothermal reaction is 80~160°C, and the time of the hydrothermal reaction is 12~48h.

[0015] Optionally, in some embodiments of this application, the step of calcining the reaction product to obtain a nitrogen-phosphorus co-doped carbon catalyst includes: calcining the reaction product at 200-400°C for 0.5-2 hours, and then calcining it at 500-1000°C for 0.5-4 hours to obtain a nitrogen-phosphorus co-doped carbon catalyst.

[0016] Optionally, in some embodiments of this application, the temperature is increased to 200-400°C at a heating rate of 0.5-5°C / min.

[0017] Optionally, in some embodiments of this application, the temperature is increased from 200-400°C to 500-1000°C at a heating rate of 0.5-5°C / min.

[0018] Optionally, in some embodiments of this application, before the step of adding polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene to a solution containing 3-aminophenol and stirring until a mixed solution is obtained, the method further includes: Ethanol and deionized water are mixed in a volume ratio of 1:1 to 5 to obtain a mixed solvent. 3-Aminophenol is dispersed in the mixed solvent to obtain a solution containing 3-aminophenol.

[0019] Secondly, this application also proposes a nitrogen-phosphorus co-doped carbon catalyst, which is prepared by the method described above.

[0020] Optionally, in some embodiments of this application, the nitrogen-phosphorus co-doped carbon catalyst is a spherical solid particle, and the spherical solid particle has a mesoporous structure distributed on it.

[0021] Thirdly, this application also proposes the application of the nitrogen-phosphorus co-doped carbon catalyst described above in electrocatalytic CO2 reduction.

[0022] The technical solution proposed in this application has the following beneficial effects: In this application, a nitrogen-phosphorus co-doped carbon catalyst with a uniformly and orderly distributed mesoporous structure on a solid sphere is prepared. The doping level of pyridine N is controlled by P doping to increase the pyridine nitrogen content. At the same time, by forming a uniform and orderly mesoporous structure throughout the sphere, a well-developed pore structure is formed, increasing the exposed catalytic active sites and facilitating the directional adsorption of carbon dioxide. This significantly improves the catalytic activity of the material, enabling it to achieve highly selective CO production at a low overpotential, showing good application prospects. Furthermore, the method of this application is simple, easy to control, and has low production costs, which is conducive to industrial production.

[0023] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0025] Figure 1 Here is a SEM image of the nitrogen-phosphorus co-doped carbon catalyst prepared in Example 4; Figure 2 This is a TEM image of the nitrogen-phosphorus co-doped carbon catalyst prepared in Example 4; Figure 3The following are BET test results for the nitrogen-phosphorus co-doped carbon catalysts prepared in Examples 1, 6 to 8; Figure 4 The pore size distribution diagrams are shown for the nitrogen-phosphorus co-doped carbon catalysts prepared in Examples 1, 6 to 8. Figure 5 The graph shows the pyridine N species content of the products prepared in Examples 1, 4, 5 and Comparative Example 1; Figure 6 The Faraday efficiency (FE) of the electrocatalytic reduction of CO2 to CO of the products prepared in Examples 1, 4, 5 and Comparative Example 1 is shown. CO Comparison chart; Figure 7 The partial current density for the electrocatalytic reduction of CO2 to CO of the products prepared in Examples 1, 4, 5, and Comparative Example 1 ( J CO Comparison chart; Figure 8 The Faraday efficiency (FE) of the electrocatalytic reduction of CO2 to H2 of the products prepared in Examples 1, 4, 5, and Comparative Example 1 is shown. H2 Comparison chart; Detailed Implementation The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0026] 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 application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0027] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0028] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0031] In the description of the embodiments of this application, the term "at least one" refers to one or more, "more than one" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces). "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0032] This application provides a nitrogen-phosphorus co-doped carbon catalyst, wherein the nitrogen-phosphorus co-doped carbon catalyst is a spherical solid particle, and the spherical solid particle has a mesoporous structure distributed on it.

[0033] Among them, quasi-spherical can be understood as "quasi-spherical" or "approximately spherical", which means that its three-dimensional shape is close to that of a standard sphere and its overall external outline is approximately circular; "solid particles" refers to particles with a compact internal structure and no hollow parts, with mesoporous structures evenly and orderly distributed on the solid particles.

[0034] The catalyst proposed in this application not only has a high level of pyridine N doping, but also has uniformly and orderly distributed mesopores, which effectively increases the exposed catalytic active sites, thereby significantly improving the catalytic activity of the material. This enables it to achieve highly selective CO production at a low overpotential, showing good application prospects.

[0035] Furthermore, this application also provides a method for preparing a nitrogen-phosphorus co-doped carbon catalyst, capable of producing the above-mentioned catalyst. The preparation method includes the following steps: S10, add polyether F127, hexamethylenetetramine (HMT), phytic acid and 1,3,5-trimethylbenzene (TMB) to the solution containing 3-aminophenol, stir until homogeneous to obtain a mixed solution.

[0036] S20, the mixed solution is subjected to a hydrothermal reaction to obtain the reaction product.

[0037] S30, the reaction product is calcined to obtain a nitrogen-phosphorus co-doped carbon catalyst.

[0038] In this reaction, HMT provides an in-situ nitrogen source, which hydrolyzes under mild conditions to generate formaldehyde and ammonia. Formaldehyde and 3-aminophenol then polymerize to form polyaminophenol / phenolic resin. Simultaneously, the amino group (-NH2) in the 3-aminophenol molecule bonds with the hydroxyl group (-OH) in polyether F127 via hydrogen bonds. Furthermore, the 1,3,5-trimethylbenzene introduced during the formation of the polymer mixture solution can co-form a homogeneous micelle solution with polyether F127 and 3-aminophenol, creating crucial conditions for constructing mesoporous microspheres. This self-assembly primarily occurs at the water interface of the mesoporous structure assembled from F127 / TMB / 3-aminophenol composite micelles. This continuous and synergistic self-assembly is beneficial for the directional growth of mesoporous materials. In addition, phytic acid is used to provide a phosphorus source and can serve as a sacrificial template to control the doping level of pyridine N.

[0039] In this application, a nitrogen-phosphorus co-doped carbon catalyst with a uniformly and orderly distributed mesoporous structure on a solid sphere is prepared. The doping level of pyridine N is controlled by P doping to increase the pyridine nitrogen content. At the same time, by forming a uniform and orderly mesoporous structure throughout the sphere, a well-developed pore structure is formed, increasing the exposed catalytic active sites and facilitating the directional adsorption of carbon dioxide. This significantly improves the catalytic activity of the material, enabling it to achieve highly selective CO production at a low overpotential, showing good application prospects. Furthermore, the method of this application is simple, easy to control, and has low production costs, which is conducive to industrial production.

[0040] In some embodiments of this application, a solution containing 3-aminophenol can be prepared by the following steps. Accordingly, before step S10, the following steps may be included: mixing ethanol and deionized water at a volume ratio of 1:1 to 5 to obtain a mixed solvent; dispersing 3-aminophenol in the mixed solvent to obtain a solution containing 3-aminophenol.

[0041] In some embodiments of this application, the mixed solution is a homogeneous micelle solution, which helps to form a uniform and ordered mesoporous material.

[0042] In some embodiments of this application, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene are added sequentially to a solution containing 3-aminophenol. The sequential addition of polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene helps promote the fusion of thermodynamically unstable emulsions and facilitates the co-assembly of the reactants into mesoporous phenolic resin spheres.

[0043] In some embodiments of this application, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene are added to a solution containing 3-aminophenol at a rotation speed of 600-800 rpm. Adding the materials under slow stirring helps to ensure uniform mixing of the materials, promote the reaction, and facilitate the formation of a homogeneous micelle solution, thereby forming a uniform and ordered mesoporous material.

[0044] In some embodiments of this application, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene are all added to a solution containing 3-aminophenol within a time range of 1 to 10 minutes. Controlling the addition time helps to form an oil-water interface so that the reaction can occur at the oil-water interface.

[0045] In step S10, the amount of raw materials added meets the following conditions: the mass ratio of polyether F127 to 3-aminophenol is 2~0.5:1; the mass ratio of hexamethylenetetramine to 3-aminophenol is 1~3:1; the mass ratio of phytic acid to 3-aminophenol is 1~3:1; and the mass ratio of 1,3,5-trimethylbenzene to 3-aminophenol is 0.2~3:11.

[0046] In step S20, the temperature of the hydrothermal reaction is 80~160℃, and the time of the hydrothermal reaction is 12~48h.

[0047] Step S30 can be implemented as follows: the reaction product is first calcined at 200-400℃ for 0.5-2 hours, and then calcined at 500-1000℃ for 0.5-4 hours to obtain a nitrogen-phosphorus co-doped carbon catalyst. Calcination in the first medium-temperature zone facilitates further thermal cross-linking of the polymer, thereby greatly improving the thermal stability of the precursor and maintaining its basic skeletal morphology. Based on this, further calcination in the second high-temperature zone allows the polymer precursor to be converted into graphitized carbon material at high temperature.

[0048] In some embodiments of this application, the temperature is increased from room temperature to 200-400°C at a heating rate of 0.5-5°C / min; and from 200-400°C to 500-1000°C at a heating rate of 0.5-5°C / min.

[0049] Thirdly, this application also proposes the application of the nitrogen-phosphorus co-doped carbon catalyst described above in electrocatalytic CO2 reduction. The above catalyst exhibits high catalytic activity and high CO selectivity, making it suitable for use as an electrocatalytic CO2 reduction catalyst.

[0050] Specifically, the above catalyst can be used to prepare a catalyst electrode for the electrocatalytic reduction of CO2 to CO. The preparation steps of this catalyst electrode are as follows: a nitrogen-phosphorus co-doped carbon catalyst is dispersed in a mixed solvent of isopropanol and ultrapure water, and a binder is added to it. The mixture is then sonicated to obtain a uniform electrode dispersion. The electrode dispersion is then coated onto carbon cloth and dried to obtain the catalyst electrode.

[0051] In this mixture, the volume ratio of isopropanol to ultrapure water is 2:8 to 5:5; the binder can be a Nafion solution with a mass concentration of 0.1wt% to 0.5wt%. In practical applications, commercially available Nafion solution (concentration approximately 20wt%) can be diluted with water to obtain a solution of the target concentration; the catalyst loading on the carbon cloth can be 0.5 mg / cm³. 2 ~5mg / cm 2 .

[0052] When performing electrocatalytic CO2 reduction to CO, a saturated calomel electrode can be used as the reference electrode, and a carbon rod as the counter electrode. The process is carried out in a CO2-saturated KHCO3 electrolyte solution, with a gas flow rate of 10–20 mL / min maintained during the measurement. The electrolysis voltage range is -0.26 V to -0.61 V (vs. RHE).

[0053] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0054] Example 1 (1) Weigh 0.5 g of 3-aminophenol into a beaker, and add 25 mL of ethanol and 55 mL of deionized water. Under slow stirring at 600 rpm, add 0.545 g of polyether F127 and 0.5 g of hexamethylenetetramine to the solution to obtain solution A. Then, add 0.5 g of phytic acid to solution A to obtain solution B. Finally, add 0.7 g of 1,3,5-trimethylbenzene to solution B, and control the overall feeding time to within 10 min to obtain a mixed solution.

[0055] (2) After the mixture is thoroughly stirred until homogeneous, transfer the mixture to a polytetrafluoroethylene-lined stainless steel autoclave, seal it, and place it in a forced-air drying oven. Set the oven temperature to 110°C and the reaction time to 24 hours. After the reaction is complete, centrifuge to collect the product and dry it overnight.

[0056] (3) The obtained product is carbonized at high temperature in a tube furnace: Under nitrogen protection, the tube furnace is heated from room temperature to 350°C at a rate of 2°C / min and held at this temperature for 1 hour. Then, the temperature is further increased to 800°C at a rate of 2°C / min and held at this temperature for 2 hours to obtain black carbon ball powder, i.e. nitrogen-phosphorus co-doped carbon catalyst.

[0057] Example 2 The scheme in this embodiment is basically the same as that in embodiment 1, except that the amount of hexamethylenetetramine added in step (1) of this embodiment is changed to 1.0g. Other than that, all other parameters and conditions remain unchanged.

[0058] Example 3 The scheme in this embodiment is basically the same as that in embodiment 1, except that the amount of hexamethylenetetramine added in step (1) is changed to 1.5g. Other than that, all other parameters and conditions remain unchanged.

[0059] Example 4 The scheme in this embodiment is basically the same as that in embodiment 1, except that the amount of phytic acid added in step (1) is changed to 1.0g. Other than that, all other parameters and conditions remain unchanged.

[0060] The morphology of the carbon sphere powder was measured using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the results are as follows: Figure 1 and Figure 2 As shown in the figure, the material consists of spherical solid particles (with a particle size of approximately 100 nm).

[0061] Example 5 The scheme in this embodiment is basically the same as that in embodiment 1, except that the amount of phytic acid added in step (1) is changed to 1.5g. Other than that, all other parameters and conditions remain unchanged.

[0062] Example 6 The scheme in this embodiment is basically the same as that in embodiment 1, except that the amount of 1,3,5-trimethylbenzene added in step (1) of this embodiment is changed to 0.1g. Other than that, all other parameters and conditions remain unchanged.

[0063] Example 7 The scheme in this embodiment is basically the same as that in embodiment 1, except that the amount of 1,3,5-trimethylbenzene added in step (1) of this embodiment is changed to 0.3g. Other than that, all other parameters and conditions remain unchanged.

[0064] Example 8 The scheme in this embodiment is basically the same as that in embodiment 1, except that the amount of 1,3,5-trimethylbenzene added in step (1) of this embodiment is changed to 1.5g. Other than that, all other parameters and conditions remain unchanged.

[0065] Comparative Example 1 This comparative example is basically the same as Example 1, except that in step (1) of this example, the amount of phytic acid added is changed to 0. Other than that, all other parameters and conditions remain unchanged.

[0066] (a) Taking the products from Examples 1, 6 to 8, the specific surface area and pore size distribution of the materials were obtained using the BET test method and the BJH model. The results are as follows: Figure 3 and Figure 4 As shown.

[0067] Results Analysis: All products in the examples exhibited mesoporous structures. Furthermore, with increasing 1,3,5-trimethylbenzene content, the mesoporous ratio of the materials initially increased and then decreased. This may be due to the accumulation of high-concentration 1,3,5-trimethylbenzene droplets during excessive 1,3,5-trimethylbenzene addition, which hindered the assembly process with F127. In comparison, the product of Example 1 exhibited the most diverse mesoporous size distribution, the largest specific surface area, and the largest pore volume. This indicates that controlling the mass ratio of 1,3,5-trimethylbenzene to 3-aminophenol to 1.4:1 is more conducive to the assembly of 1,3,5-trimethylbenzene and F127 into uniform nanomicelles.

[0068] (ii) Take the products obtained in Examples 1 to 3 and use X-ray photoelectron spectroscopy (XPS) to detect the total nitrogen content in the materials. Record the results in Table 1.

[0069] Table 1

[0070] It can be seen that by controlling the amount of hexamethylenetetramine, the doping level of N atoms can be effectively regulated.

[0071] (III) The products obtained in Examples 1, 4, 5, and Comparative Example 1 were analyzed using X-ray photoelectron spectroscopy (XPS), and the content of pyridine N species in the materials was determined from the peak area ratio. The results are as follows: Figure 5 As shown.

[0072] It can be seen that the P source is used as a sacrificial template to control the doping level of pyridine N. When the amount of phytic acid is 1.0 g, the prepared material has a high pyridine N content (1.02 at.%).

[0073] (iv) The products obtained in Examples 1 to 5 and Comparative Example 1 were subjected to electrochemical performance testing using a three-electrode system: 0.8 mg of the sample was dispersed in a mixed solvent of 0.3 mL isopropanol and 0.7 mL ultrapure water (volume ratio 3:7). 2 μL of Nafion solution was added to the above solution and ultrasonically dispersed for 30 min to obtain an electrode dispersion. The electrode dispersion was taken with a pipette and completely dripped onto a 1 cm × 1 cm carbon cloth, which was then dried with an infrared lamp for later use. Using this electrode as the working electrode, a saturated calomel electrode as the reference electrode, and a carbon rod as the counter electrode, a CO2-saturated 0.5 mol / L KHCO3 electrolyte solution was used as the electrolyte to test the electrochemical performance of the catalyst in an H-type electrolytic cell. During the test, a sufficient amount of CO2 was passed through the reaction electrode, and the flow rate of CO2 was controlled at 13 mL / min. The electrolysis voltage range was -0.26 V to -0.61 V (vs. RHE). Quantitative analysis was performed by gas chromatography and 1H NMR.

[0074] The catalysts prepared in Examples 1, 2, and 3 were tested and found to have maximum Faradaic efficiencies of 63%, 75%, and 70% respectively at -0.41 V (vs. RHE) for CO production. As can be seen from the data in Table 1, by controlling the amount of hexamethylenetetramine and increasing the N atom doping level, the catalytic activity and selectivity of the catalysts were improved. In addition, see Figure 6 , Figure 7 and Figure 8As can be seen, compared to H2 production selectivity, the catalysts of Examples 1, 4, and 5 exhibited higher CO production selectivity at lower potentials. Furthermore, compared to Comparative Example 1, it can be seen that the product of Comparative Example 1 exhibited the lowest CO selectivity at all applied potentials, reaching the maximum FE at -0.46 V (vs. RHE). CO The selectivity for carbon monoxide production from carbon dioxide reduction was 54%. However, doping with phosphorus significantly improved the selectivity, and the material prepared with 1.0 g of phytic acid exhibited the highest CO selectivity and catalytic activity within the measured voltage range: at -0.41 V (vs. RHE), its FE... CO The maximum current density reached 91.5%, and at -0.61 V (vs. RHE), its CO portion current density reached -5.1 mA / cm². 2 It is much higher than the -1.54 mA / cm of Comparative Example 1. 2 .

[0075] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a nitrogen-phosphorus co-doped carbon catalyst, characterized in that, Includes the following steps: Add polyether F127, hexamethylenetetramine, phytic acid and 1,3,5-trimethylbenzene to a solution containing 3-aminophenol, stir until homogeneous, and obtain a mixed solution; The mixed solution was subjected to a hydrothermal reaction to obtain the reaction product; The reaction product was calcined to obtain a nitrogen-phosphorus co-doped carbon catalyst.

2. The preparation method according to claim 1, characterized in that, To a solution containing 3-aminophenol, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene are added sequentially; and / or, At a rotation speed of 600-800 rpm, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene were added to a solution containing 3-aminophenol; and / or, Within a time range of 1 to 10 minutes, polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene were added to a solution containing 3-aminophenol; and / or, The mixed solution is a homogeneous micelle solution.

3. The preparation method according to claim 1, characterized in that, The mass ratio of polyether F127 to 3-aminophenol is 2~0.5:1; and / or, The mass ratio of hexamethylenetetramine to 3-aminophenol is 1 to 3:1; and / or, The mass ratio of phytic acid to 3-aminophenol is 1~3:1; and / or, The mass ratio of 1,3,5-trimethylbenzene to 3-aminophenol is 0.2~3:

11.

4. The preparation method according to claim 1, characterized in that, The hydrothermal reaction temperature is 80~160℃, and the hydrothermal reaction time is 12~48h.

5. The preparation method according to claim 1, characterized in that, The step of calcining the reaction product to obtain a nitrogen-phosphorus co-doped carbon catalyst includes: calcining the reaction product at 200-400℃ for 0.5-2h, and then calcining it at 500-1000℃ for 0.5-4h to obtain a nitrogen-phosphorus co-doped carbon catalyst.

6. The preparation method according to claim 5, characterized in that, Heating to 200-400℃ at a heating rate of 0.5-5℃ / min; and / or, The temperature is increased from 200~400℃ to 500~1000℃ at a heating rate of 0.5~5℃ / min.

7. The preparation method according to claim 1, characterized in that, Before the step of adding polyether F127, hexamethylenetetramine, phytic acid, and 1,3,5-trimethylbenzene to a solution containing 3-aminophenol and stirring until a mixed solution is obtained, the following steps are also included: Ethanol and deionized water are mixed in a volume ratio of 1:1 to 5 to obtain a mixed solvent. 3-Aminophenol is dispersed in the mixed solvent to obtain a solution containing 3-aminophenol.

8. A nitrogen-phosphorus co-doped carbon catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. The nitrogen-phosphorus co-doped carbon catalyst according to claim 8, characterized in that, The nitrogen-phosphorus co-doped carbon catalyst is a spherical solid particle, and the spherical solid particle has a mesoporous structure distributed on it.

10. The application of the nitrogen-phosphorus co-doped carbon catalyst according to claim 8 or 9 in electrocatalytic CO2 reduction.

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