A phosphorus-doped cobalt-molybdenum alloy electrode, a preparation method and application thereof

Abstract

This application relates to the field of electrocatalysts and their preparation technology, specifically to a phosphorus-doped cobalt-molybdenum alloy electrode, its preparation method, and its application. This application solves the problem of low Faradaic efficiency and yield in existing electrocatalytic conversion of nitrate to ammonia. The catalyst for nitrate-to-ammonia reduction with a nanosheet structure obtained by phosphating a sample prepared from a Co and Mo composite exhibits excellent Faradaic efficiency and yield in nitrate-to-ammonia reduction. Test results show that the prepared P-CoMo / NF nanoalloy catalyst achieves an ammonia yield as high as 13700.49 μg h⁻¹ in a mixed solution of 1 mol / L KOH and 0.1 mol / L KNO₃ at -0.5 V vs. RHE. ‑1 cm ‑2 The Faraday efficiency remained at 91.69%. Furthermore, the ammonia yield and Faraday efficiency remained stable over 10 cycles at -0.5V vs. RHE.

Description

Technical Field

[0001] This application relates to the field of electrocatalysts and their preparation technology, specifically to a phosphorus-doped cobalt-molybdenum alloy electrode, its preparation method, and its application. Background Technology

[0002] Ammonia, as a key basic chemical, plays an indispensable role in modern agriculture and the chemical industry. It is a core raw material for synthesizing nitrogen fertilizers and an important precursor for many fine chemicals. In recent years, ammonia has been regarded as a highly promising carbon-free energy carrier due to its high energy density and hydrogen storage capacity. However, current global ammonia production mainly relies on the Haber-Bosch process, which requires harsh high-temperature and high-pressure conditions. This process not only consumes a large amount of energy but also results in significant carbon dioxide emissions, contradicting the global goal of carbon neutrality.

[0003] Against this backdrop, the electrochemical method for reducing nitrates to ammonia has attracted widespread attention. This reaction can be carried out under mild ambient temperature and pressure conditions, using nitrates, which are widely present in water, as a raw material. It demonstrates a dual value of "turning waste into treasure," particularly in treating nitrate pollutants in agricultural runoff and industrial wastewater. However, the reduction of nitrates is a complex reaction involving the transfer of eight electrons and nine protons, and its reaction mechanism is not yet fully understood. Existing catalytic systems generally face bottlenecks in catalytic activity and selectivity, making it difficult to efficiently drive the reaction.

[0004] Furthermore, in the cathode process of electrocatalytic nitrate reduction, the hydrogen evolution reaction (HER) is a major competing side reaction that readily occurs and consumes a large number of electrons and protons required for the reaction. This directly leads to generally low Faraday efficiency and yield of the target product ammonia, severely restricting the practical application and promotion of this technology.

[0005] Therefore, developing a high-performance electrocatalytic material that can simultaneously enhance the activity and selectivity of nitrate reduction and effectively suppress the hydrogen evolution reaction is a key technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0006] Based on this, in order to solve the problem of low Faraday efficiency and low yield in the existing conversion of nitrate to ammonia, this application provides a phosphorus-doped cobalt-molybdenum alloy electrode, its preparation method and application.

[0007] This application provides a method for preparing a phosphorus-doped cobalt-molybdenum alloy electrode, comprising the following steps: S1. The conductive substrate is immersed in a solution containing soluble cobalt salt and soluble molybdate, and a hydrothermal reaction is carried out to generate a cobalt-molybdenum bimetallic oxide precursor on the surface of the conductive substrate. S2. The conductive substrate with the precursor on its surface obtained in step S1 is subjected to heat treatment with a phosphorus-containing compound under a protective atmosphere to obtain the phosphorus-doped cobalt-molybdenum alloy electrode.

[0008] In some embodiments, the conductive substrate is nickel foam.

[0009] In some embodiments, the soluble cobalt salt is cobalt nitrate, and the soluble molybdate is ammonium molybdate.

[0010] In some embodiments, the solution in step S1 further contains urea and ammonium fluoride.

[0011] In some embodiments, the hydrothermal reaction in step S1 is carried out at a temperature of 140-160°C for 4-6 hours.

[0012] In some embodiments, in step S2, the phosphorus-containing compound is sodium hypophosphite, and the heat treatment process involves heating to 400-600°C at a heating rate of 2-5°C / min and holding at that temperature for 40-80 minutes.

[0013] In some embodiments, the amount of cobalt nitrate and ammonium molybdate in the solution of step S1 is 0.5-1g.

[0014] In some embodiments, the amount of urea in the solution of step S1 is 0.4-1g, and the amount of ammonium fluoride is 0.1-0.5g.

[0015] Another aspect of this application provides a phosphorus-doped cobalt-molybdenum alloy electrode, comprising a conductive substrate and a phosphorus-doped cobalt-molybdenum alloy layer grown on the surface of the conductive substrate.

[0016] This application also provides the application of the phosphorus-doped cobalt-molybdenum alloy electrode in the electrocatalytic reduction of nitrate to produce ammonia.

[0017] This application has the following beneficial effects: This application significantly enhances the adsorption and activation capacity of nitrates by regulating the electronic structure of CoMo alloys through phosphorus doping and combining the synergistic catalytic effect of Co and Mo, while effectively suppressing the hydrogen evolution side reaction, thereby greatly improving the Faraday efficiency and yield of ammonia generation.

[0018] The electrode prepared in this application has a unique nanoneedle array structure, which is directly grown on a three-dimensional conductive substrate to form a self-supporting monolithic electrode. This structure exposes a huge specific surface area, provides abundant active sites, and ensures efficient electron transport and mass exchange.

[0019] The phosphorus-doped CoMo alloy electrode provided in this application exhibits excellent performance, achieving an ammonia yield as high as 13700.49 μg h⁻¹ at a potential of -0.5 V vs. RHE. -1 cm -2 The Faraday efficiency remained at 91.69%, and the performance remained stable after 10 cycles of testing, demonstrating great potential for industrial applications.

[0020] The preparation method of this application is simple, the raw materials are readily available, the cost is controllable, and it is easy to realize large-scale production, providing a practical and feasible technical path for developing high-performance nitrate reduction catalysts for ammonia production. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a comparison of the current density versus voltage curves of the electrodes prepared in Example 1 and Comparative Examples 1-2; Figure 2 A comparison chart showing the yield of ammonia prepared using the electrodes obtained in Example 1 and Comparative Examples 1-2; Figure 3 This is a comparison chart of the Faraday efficiency of the electrodes prepared in Example 1 and Comparative Examples 1-2; Figure 4 The graph shows a performance comparison of the electrodes prepared in Example 1 and Comparative Examples 1-2 under -0.5V vs. RHE voltage for 10 cycles. Detailed Implementation

[0023] The present application will be further described in detail below with reference to the embodiments and examples. It should be understood that these embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to enable a more thorough and comprehensive understanding of the disclosure of the present application. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. Furthermore, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0024] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0025] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings: The terms "and / or," "or / and," and "and / or" as used herein include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND," and also undoubtedly includes technical solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0026] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0027] The terms “combinations of,” “any combination of,” and “any combination of” used in this article include all suitable combinations of any two or more of the listed items.

[0028] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0029] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0030] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0031] In this application, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions composed of the listed features.

[0032] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0033] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0034] In this application, % (w / w) and wt% both represent weight percentage, % (v / v) refers to volume percentage, and % (w / v) refers to mass-volume percentage.

[0035] All references to documents mentioned in this application are incorporated herein by reference as if each document were individually incorporated herein by reference. Unless they conflict with the inventive purpose and / or technical solution of this application, all cited documents are incorporated herein by reference in their entirety and for all purposes. When citing documents in this application, the definitions of relevant technical features, terms, nouns, phrases, etc., are also incorporated herein by reference. When citing documents in this application, examples and preferred embodiments of the cited technical features may also be incorporated herein by reference, but only to the extent that they enable the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, this application shall prevail or modifications shall be made adaptably to the description in this application.

[0036] The first aspect of this application provides a method for preparing a phosphorus-doped cobalt-molybdenum alloy electrode, comprising the following steps: S1, immersing a conductive substrate in a solution containing soluble cobalt salt and soluble molybdate, and performing a hydrothermal reaction to generate a cobalt-cobalt bimetallic oxide precursor on the surface of the conductive substrate; S2, heat-treating the conductive substrate with the precursor on its surface obtained in step S1 with a phosphorus-containing compound under a protective atmosphere to obtain the phosphorus-doped cobalt-molybdenum alloy electrode.

[0037] This preparation method successfully solved the core technical problems through ingenious design. First, a conductive substrate (such as nickel foam) was used as the electrode framework. Its three-dimensional porous structure greatly increased the loading area of ​​the active material and facilitated the mass transfer of reactants and products. Second, the in-situ growth of the CoMoO4 precursor via hydrothermal method ensured the uniform composite of cobalt and molybdenum at the atomic level, laying the structural foundation for the subsequent formation of an alloy with synergistic catalytic effects. Most importantly, the oxide precursor was converted into a phosphorus-doped CoMo alloy through a phosphating heat treatment step. The introduction of phosphorus atoms can effectively regulate the electronic structure of the alloy, optimize its adsorption and activation ability for nitrates, and thus accelerate the main reaction kinetics.

[0038] Simultaneously, phosphorus doping can alter the hydrogen evolution reaction barrier on the electrode surface, effectively suppressing competitive hydrogen evolution reactions and directing more electrons and protons towards the nitrate reduction pathway. This dual mechanism of enhancing the main reaction and suppressing side reactions together endows the electrode with excellent ammonia yield and Faraday efficiency. Specifically, the conductive substrate can be selected from nickel foam, copper foam, or carbon cloth, preferably nickel foam, due to its advantages of high conductivity, large specific surface area, and low cost. The soluble cobalt salt can be selected from cobalt nitrate, cobalt chloride, or cobalt sulfate, preferably cobalt nitrate. The soluble molybdate can be selected from ammonium molybdate or sodium molybdate, preferably ammonium molybdate. The phosphorus-containing compound can be selected from sodium hypophosphite, red phosphorus, or triphenylphosphine, preferably sodium hypophosphite, because the PH3 gas produced by its decomposition has strong reducing properties and excellent phosphating effect.

[0039] In some embodiments, the conductive substrate is nickel foam. The excellent conductivity and three-dimensional interconnected pore structure of nickel foam provide efficient channels for rapid electron transport and ion diffusion, making it an ideal carrier for constructing self-supporting electrodes.

[0040] In some embodiments, the soluble cobalt salt is cobalt nitrate, and the soluble molybdate is ammonium molybdate. These two raw materials are inexpensive, widely available, and exhibit good solubility and stability in aqueous solutions, making them common precursors for the preparation of cobalt-molybdenum-based materials.

[0041] In some embodiments, the solution in step S1 further contains urea and ammonium fluoride. Urea hydrolyzes during the hydrothermal process to provide the OH groups required for precipitation.- Ions contribute to the uniform nucleation of metal oxides; ammonium fluoride, as a morphology control agent, can induce the formation of nanoneedle-like or nanosheet-like microstructures, thereby significantly increasing the specific surface area of ​​the catalyst and exposing more active sites.

[0042] In some embodiments, the hydrothermal reaction in step S1 is carried out at a temperature of 140-160°C for 4-6 hours. This temperature and time range is a preferred process window for forming a well-crystallized CoMoO4 precursor with a regular morphology. Specifically, the hydrothermal temperature can be selected from any value among 140°C, 145°C, 150°C, 155°C, or 160°C; the hydrothermal time can be selected from any value among 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours.

[0043] In some embodiments, in step S2, the phosphorus-containing compound is sodium hypophosphite, and the heat treatment process involves heating to 400-600°C at a heating rate of 2-5°C / min and holding at that temperature for 40-80 min. Sodium hypophosphite is a commonly used solid phosphorus source and is easy to handle. This range of heat treatment parameters is crucial to ensuring sufficient phosphating of the CoMoO4 precursor and the formation of a highly crystalline P-CoMo alloy, while avoiding particle sintering and growth or reduced activity due to excessively high temperatures. Specifically, the heating rate can be selected from any value among 2°C / min, 3°C / min, 4°C / min, or 5°C / min; the heat treatment temperature can be selected from any value among 400°C, 450°C, 500°C, 550°C, or 600°C; and the holding time can be selected from any value among 40 min, 50 min, 60 min, 70 min, or 80 min.

[0044] In some embodiments, the amount of cobalt nitrate and ammonium molybdate in the solution of step S1 is 0.5-1g. This dosage range can control the atomic ratio of cobalt elements, with a preferred ratio of 1:1, which is beneficial for forming a CoMo alloy with optimal synergistic effect.

[0045] In some embodiments, the amount of urea in the solution of step S1 is 0.4-1 g, and the amount of ammonium fluoride is 0.1-0.5 g. This range of amounts is the preferred condition for achieving the ideal morphology of the precursor.

[0046] A second aspect of this application provides a phosphorus-doped cobalt-molybdenum alloy electrode, comprising a conductive substrate and a phosphorus-doped cobalt-cobalt alloy layer grown on the surface of the conductive substrate. This electrode, prepared by the above method, is a binder-free, self-supporting electrode with excellent conductivity and structural stability. The phosphorus-doped cobalt-cobalt alloy layer serves as the core catalytic component, providing abundant and highly active reaction sites.

[0047] The third aspect of this application provides the application of the aforementioned phosphorus-doped cobalt-cobalt alloy electrode in the electrocatalytic reduction of nitrates to ammonia. This electrode is particularly suitable for electrocatalytic reactions in alkaline electrolytes, enabling the efficient and selective conversion of nitrate pollutants in water into ammonia, which has high economic value, thus achieving the dual goals of environmental remediation and resource recovery.

[0048] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0049] In the specific embodiments described below, the measurement parameters involving raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. Temperature and time parameters are subject to acceptable deviations due to instrument testing accuracy or operational precision.

[0050] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0051] Example 1: This example provides a phosphorus-doped cobalt-molybdenum alloy electrode and its preparation method.

[0052] Raw materials for preparation: Conductive substrate: 1 mm thick, 1 cm² in area 2 Commercially available nickel foam.

[0053] Cobalt source: Cobalt nitrate hexahydrate (Co(NO3)2·6H2O), analytical grade, 0.8g.

[0054] Molybdenum source: Ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 ·4H2O), analytical grade, 0.8g.

[0055] Additives: Urea, 0.45g; Ammonium fluoride (NH4F), 0.12g.

[0056] Solvent: Deionized water, 70 mL.

[0057] Phosphorus source: anhydrous sodium hypophosphite (NaH2PO2), 1.0g.

[0058] Preparation method: (1) The nickel foam was ultrasonically cleaned for 20 minutes each in acetone, 3M dilute hydrochloric acid, anhydrous ethanol and deionized water, and then dried in an oven at 60°C for later use.

[0059] (2) Dissolve 0.8 g of cobalt nitrate hexahydrate, 0.8 g of ammonium molybdate tetrahydrate, 0.45 g of urea, and 0.12 g of ammonium fluoride in 70 mL of deionized water and stir until homogeneous to obtain a precursor solution. Completely immerse the dried nickel foam in this solution, then transfer the entire system to a hydrothermal reactor and react at 150 °C for 4.5 hours. After the reaction, allow it to cool naturally to room temperature, remove the sample, wash it several times alternately with deionized water and anhydrous ethanol, and dry it at 60 °C for 60 minutes to obtain nickel foam (CoMoO4 / NF) with the CoMoO4 precursor loaded on its surface.

[0060] (3) Place 1.0 g of anhydrous sodium hypophosphite and the CoMoO4 / NF sample obtained in step (2) at the upstream and downstream ends of a tube furnace, respectively. Under continuous nitrogen gas flow (flow rate of 100 sccm), the temperature is increased to 450 °C at a heating rate of 2 °C / min and held for 45 minutes. After the reaction is complete, allow it to cool naturally to room temperature, remove the sample, and obtain a phosphorus-doped cobalt alloy electrode, denoted as P-CoMo / NF.

[0061] Example 2: The difference between this example and Example 1 is that the conductive substrate is copper foam, while the remaining steps and parameters are the same as in Example 1.

[0062] Example 3: The difference between this example and Example 1 is that the hydrothermal reaction temperature in step (2) is 160°C and the time is 4 hours. The remaining steps and parameters are the same as in Example 1.

[0063] Example 4: The difference between this example and Example 1 is that the phosphating heat treatment temperature in step (3) is 500°C and the holding time is 60 min. The remaining steps and parameters are the same as in Example 1.

[0064] Example 5: The difference between this example and Example 1 is that the amount of cobalt nitrate used in step (2) is 0.5g and the amount of ammonium molybdate is 1.0g. The remaining steps and parameters are the same as in Example 1.

[0065] Example 6: The difference between this example and Example 1 is that the heating rate of the phosphating heat treatment in step (3) is 5℃ / min, and the other steps and parameters are the same as in Example 1.

[0066] Comparative Example 1 The difference between this comparative example and Example 1 is that anhydrous sodium hypophosphite is not added during step (3), while the remaining process steps and parameter settings are the same as in Example 1, resulting in a phosphorus-doped CoMo alloy electrode.

[0067] Comparative Example 2 The difference between this comparative example and Example 1 is that only step (2) is performed to obtain the CoMoO4 electrode.

[0068] Comparative Example 3 The only difference between this comparative example and Example 1 is that ammonium molybdate tetrahydrate is not added to the precursor solution in step (2). The remaining steps and parameters are the same as in Example 1, and a phosphorus-doped cobalt electrode (P-Co / NF) is finally obtained.

[0069] Performance Testing and Results Analysis Test method: Electrodes prepared in the above examples and comparative examples were used as working electrodes, with a carbon rod as the counter electrode and a reversible hydrogen electrode as the reference electrode. Electrochemical tests were conducted in a mixed electrolyte of 1 mol / L KOH and 0.1 mol / L KNO3. The ammonia content generated during the reaction was determined by Nessler's reagent spectrophotometry, and the ammonia yield and Faraday efficiency were calculated accordingly. Stability tests were conducted at a constant potential of -0.5 V vs. RHE, with each test lasting 1 hour, repeated for 10 cycles.

[0070] Result verification: (1) The current density of the catalysts prepared in Example 1 and Comparative Examples 1-2 was tested, and the results are as follows: Figure 1 As shown, by Figure 1 It can be seen that the current density of the phosphorus-doped CoMo alloy electrode prepared in Example 1 is significantly higher than that of the electrodes prepared in Comparative Examples 1-2. This is because the Co nanoneedles are loaded with Mo and phosphated, which improves the ability to capture nitrate ions and accelerates the decomposition of water, which is beneficial to the subsequent hydrogenation reaction after nitrate reduction. The current density of Comparative Example 3 is too high due to the violent hydrogen evolution reaction that accompanies the NO3RR reaction. Compared with Example 1, it is shown that the addition of Mo is beneficial to the migration of activated hydrogen to the hydrogenation step and reduces the impact of byproducts on subsequent steps.

[0071] (2) The ammonia yields of the catalysts prepared in Example 1 and Comparative Examples 1-2 were measured at different voltages in a mixed solution of 1 mol / L KOH and 0.1 mol / L KNO3. The results are as follows: Figure 2 As shown, by Figure 2 It can be seen that the ammonia yield of the phosphorus-doped CoMo alloy electrode prepared in Example 1 is much higher than that of the CoN / MoN electrode and CoMoO4 electrode prepared in Comparative Examples 1-2. This is because phosphorus doping accelerates the reduction of nitrates by Co and Mo. Furthermore, as the voltage gradually becomes more negative, the ammonia yield of the phosphorus-doped CoMo alloy electrode continuously increases, reaching 13700.49 μg / h at -0.5V vs. RHE. -1 cm -2. Figure 2 It can be observed that the catalyst prepared in Comparative Example 3 has a higher yield, which is due to the doping of P. However, by combining the Faraday efficiency results, it can be found that the overall performance of Example 1 is the best.

[0072] (3) The Faraday efficiency of the catalysts prepared in Example 1 and Comparative Examples 1-3 was measured at different voltages in a mixed solution of 1 mol / L KOH and 0.1 mol / L KNO3. The results are as follows: Figure 3 As shown, by Figure 3 It can be seen that the Faraday efficiency of the phosphorus-doped CoMo alloy electrode can reach over 90% at -0.5V vs. RHE, which is better than that of comparative examples 1-3.

[0073] (4) Figure 4 The graph shows the performance of the P-CoMo / NF catalyst prepared in Example 1 after 10 cycles at -0.5V vs. RHE. As can be seen from the graph, the Faradaic efficiency and ammonia yield of the catalyst remained stable during the 10 cycles, indicating that the phosphorus-doped CoMo alloy electrode has good stability.

[0074] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Furthermore, it should be understood that after reading the above teachings of this application, those skilled in the art can make various alterations or modifications to this application, and the equivalent forms obtained also fall within the scope of protection of this application. It should also be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a phosphorus-doped cobalt-molybdenum alloy electrode, characterized in that, Includes the following steps: S1. The conductive substrate is immersed in a solution containing soluble cobalt salt and soluble molybdate, and a hydrothermal reaction is carried out to generate a cobalt-molybdenum bimetallic oxide precursor on the surface of the conductive substrate. S2. The conductive substrate with the precursor on its surface obtained in step S1 is subjected to heat treatment with a phosphorus-containing compound under a protective atmosphere to obtain the phosphorus-doped cobalt-molybdenum alloy electrode.

2. The method for preparing the phosphorus-doped cobalt-molybdenum alloy electrode according to claim 1, characterized in that, The conductive substrate is nickel foam.

3. The method for preparing the phosphorus-doped cobalt-molybdenum alloy electrode according to claim 1, characterized in that, The soluble cobalt salt is cobalt nitrate, and the soluble molybdate is ammonium molybdate.

4. The method for preparing the phosphorus-doped cobalt-molybdenum alloy electrode according to claim 1, characterized in that, The solution in step S1 also contains urea and ammonium fluoride.

5. The method for preparing the phosphorus-doped cobalt-molybdenum alloy electrode according to claim 1, characterized in that, The hydrothermal reaction in step S1 is carried out at a temperature of 140-160℃ for 4-6 hours.

6. The method for preparing the phosphorus-doped cobalt-molybdenum alloy electrode according to claim 1, characterized in that, In step S2, the phosphorus-containing compound is sodium hypophosphite, and the heat treatment process involves heating to 400-600℃ at a heating rate of 2-5℃ / min and holding at that temperature for 40-80min.

7. The method for preparing the phosphorus-doped cobalt-molybdenum alloy electrode according to claim 3, characterized in that, In the solution of step S1, the amount of cobalt nitrate is 0.5-1g and the amount of ammonium molybdate is 0.5-1g.

8. The method for preparing the phosphorus-doped cobalt-molybdenum alloy electrode according to claim 4, characterized in that, In the solution of step S1, the amount of urea used is 0.4-1g, and the amount of ammonium fluoride used is 0.1-0.5g.

9. A phosphorus-doped cobalt-molybdenum alloy electrode, characterized in that, It includes a conductive substrate and a phosphorus-doped cobalt-molybdenum alloy layer grown on the surface of the conductive substrate.

10. The application of a phosphorus-doped cobalt-molybdenum alloy electrode as described in claim 9 in the electrocatalytic reduction of nitrate to ammonia.

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