CoMo alloy catalyst for electro-catalysis nitrate reduction reaction and preparation method of CoMo alloy catalyst
By preparing CoMo alloy catalysts, especially β-Co(OH)2/Co85Mo15 catalysts, the problem of insufficient activity and stability of cobalt-based catalysts in low-concentration nitrate environments has been solved, realizing highly efficient electrocatalytic nitrate reduction reactions, which are suitable for industrial applications.
Patent Information
- Application Number
- CN202511530165.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-24
- Publication Date
- 2026-02-17
AI Technical Summary
Existing cobalt-based catalysts suffer from weak NO3- adsorption capacity, intense competition for hydrogen evolution reaction, and limited hydrogenation reaction capacity under low-concentration nitrate environments, resulting in insufficient catalytic efficiency and stability, making it difficult to efficiently electrocatalyze the nitrate reduction reaction.
A β-Co(OH)2/Co85Mo15 catalyst was prepared by electrodeposition using a CoMo alloy catalyst. The multivalent sites of molybdenum were used to enhance NO3- adsorption and suppress hydrogen evolution reaction. The structural stability of the catalyst was improved by electrochemical reconstruction.
The catalyst's activity and stability in low-concentration nitrate environments were improved, and ammonia selectivity was enhanced, achieving high Faraday efficiency and high ammonia selectivity, making it suitable for industrial applications.
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Figure CN121538673A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to catalysts and their preparation methods, belonging to the field of electrocatalysis, and particularly to CoMo alloy catalysts for electrocatalytic nitrate reduction reactions and their preparation methods. Background Technology
[0002] Currently, electrocatalytic nitrate reduction reaction (NRR) still faces many challenges in low-nitrate environments, especially given competition from hydrogen evolution reaction (HER). Among existing technologies, cobalt-based catalysts have made some progress in nitrate reduction, but their performance is limited by the following factors:
[0003] Weak NO3 - Adsorption capacity: Cobalt-based catalysts typically exhibit high adsorption capacity in low-concentration nitrate systems due to NO3. - Its weak adsorption capacity leads to insufficient catalytic efficiency.
[0004] Competition for hydrogen evolution reaction: In electrocatalytic reactions, HER and nitrate reduction reactions often have overlapping reaction potentials, and the generation of hydrogen can easily interfere with the progress of nitrate reduction reaction.
[0005] Limited hydrogenation reactivity: Cobalt-based catalysts have weak hydrogenation reactivity, limiting the production of intermediate products (such as NO2). - The further conversion of ) into ammonia (NH3).
[0006] In existing technologies, although cobalt-based catalysts have achieved nitrate reduction to some extent, their relatively weak NO3- content hinders their effectiveness. - The adsorption capacity and suboptimal hydrogenation capacity still prevent efficient operation in low-concentration nitrate environments. Furthermore, the competitive nature of the HER reaction generates byproducts, further reducing ammonia selectivity. Especially in practical applications with low-concentration nitrates, there is a general lack of effective strategies to simultaneously address the catalyst's activity and stability issues. Summary of the Invention
[0007] The purpose of this invention is to overcome the defects and problems of poor catalyst activity and stability in the low-concentration nitrate environment in the prior art, and to provide a CoMo alloy catalyst with good catalyst activity and stability in the low-concentration nitrate environment for electrocatalytic nitrate reduction reaction and its preparation method.
[0008] To achieve the above objectives, the technical solution of the present invention is: a method for preparing a CoMo alloy catalyst for electrocatalytic nitrate reduction reaction, comprising:
[0009] Step 1: After stirring and mixing deionized water, cobalt salt, molybdate, hydroxycarboxylic acid, and ammonium salt, a CoMo electrolyte is obtained.
[0010] Step 2: Using a carbon rod as the counter electrode, silver / silver chloride filled with saturated potassium chloride solution as the reference electrode, and nickel foam as the working electrode, electrodeposit CoMo electrolyte to obtain a CoMo electrode sample.
[0011] Step 3: Using the CoMo electrode sample as the cathode and the carbon rod as the anode, an electrochemical reduction reaction is carried out in an H-type electrolytic cell to obtain β-Co(OH)2 / Co at the cathode. 85 Mo 15 catalyst;
[0012] The cathode chamber of the H-type electrolytic cell is filled with a mixed solution of potassium hydroxide and potassium nitrate as the catholy solution, and the anode chamber of the H-type electrolytic cell is filled with potassium hydroxide as the anolyte.
[0013] The process of obtaining the CoMo electrolyte specifically includes:
[0014] Add 0.075–0.095 mol of cobalt salt, 0.005–0.025 mol of molybdate, 0.005–0.015 mol of hydroxycarboxylic acid, and 0.01–0.02 mol of ammonium salt to 40–60 mL of deionized water; stir continuously for 15–25 minutes to dissolve and obtain a uniformly dispersed CoMo electrolyte.
[0015] The process of obtaining the CoMo electrode sample specifically includes:
[0016] Using a carbon rod as the counter electrode, silver / silver chloride filled with saturated potassium chloride solution as the reference electrode, and nickel foam with an effective deposition area of 0.3 × 0.3 cm² as the working electrode, electrodeposition was carried out at a constant current density of 1.1–1.3 A / cm² until a black solid deposit was formed on the working electrode, thus obtaining a CoMo electrode sample.
[0017] The β-Co(OH)2 / Co obtained on the cathode 85 Mo 15 Catalysts, specifically including:
[0018] Using a CoMo electrode sample as the cathode and a carbon rod as the anode, the reaction was carried out in an H-type electrolytic cell at a constant current density of 0.95–1.5 A / cm² until a black solid deposit formed on the cathode, yielding β-Co(OH)₂ / Co. 85 Mo 15 catalyst.
[0019] The cobalt salt includes any one or any combination of hydrated cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate;
[0020] The molybdate includes any one or any combination of hydrated sodium molybdate, anhydrous sodium molybdate, potassium molybdate, and ammonium metamolybdate.
[0021] The hydroxycarboxylic acid includes any one or any combination of citric acid, lactic acid, malic acid, and tartaric acid.
[0022] The ammonium salt includes any one or any combination of ammonium chloride, ammonium sulfate, and ammonium nitrate.
[0023] The catholy solution is a mixed solution of potassium hydroxide with a concentration of 0.5-1.5 mol and potassium nitrate with a concentration of 0.05-0.15 mol; the anolyte is potassium hydroxide with a concentration of 0.5-1.5 mol.
[0024] The atomic ratio of Co:Mo in the CoMo electrolyte includes any one of 0.85:0.15, 0.95:0.05, 0.9:0.1, 0.85:0.15, and 0.80:0.20.
[0025] A CoMo alloy catalyst, wherein the CoMo alloy catalyst is a black β-Co(OH)2 / Co 85 Mo 15 catalyst.
[0026] In the CoMo alloy catalyst, β-Co(OH)2 and Co 85 Mo 15 It exhibits a dual-phase heterostructure with coexisting metallic phases; the β-Co(OH)₂ phase exhibits a layered nanosheet structure, and Co… 85 Mo 15 The phase is uniformly dispersed in the form of nanocrystals or particles within or at the interface of β-Co(OH)2, and β-Co(OH)2 reacts with Co. 85 Mo 15 There is a continuous lattice transition and strain-matched interface between them.
[0027] The multivalent states of Mo in the CoMo alloy catalyst include at least Mo. 4+ Mo 5+ and Mo 6+ .
[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0029] 1. This invention discloses a CoMo alloy catalyst for electrocatalytic nitrate reduction and its preparation method. The method first involves mixing deionized water, cobalt salt, molybdate, hydroxycarboxylic acid, and ammonium salt to obtain a CoMo electrolyte. Next, using a carbon rod as the counter electrode, silver / silver chloride filled with saturated potassium chloride solution as the reference electrode, and nickel foam as the working electrode, the CoMo electrolyte is electrodeposited to obtain a CoMo electrode sample on the working electrode. Finally, the CoMo electrode sample is used as the cathode, and an electrochemical reduction reaction is carried out in an H-type electrolytic cell to obtain β-Co(OH)2 / Co on the cathode. 85 Mo 15 Catalyst; In application, this design enhances the catalyst's resistance to NO3 by introducing multiple valence sites of molybdenum. - The adsorption of the catalyst solves the performance bottleneck of traditional catalysts in the reduction reaction of low-concentration nitrates, and the structural stability of the catalyst is improved through electrochemical reconstruction, so that it can maintain high activity and stability during long-term reactions.
[0030] 2. In the CoMo alloy catalyst for electrocatalytic nitrate reduction reaction and its preparation method of the present invention, the CoMo alloy catalyst is a black β-Co(OH)2 / Co 85 Mo 15 Catalyst; In this application, the surface structure of the molybdenum-cobalt-doped alloy was reconstructed to suppress the hydrogen evolution reaction and improve the selectivity of ammonia. Furthermore, the electrochemical reconstruction technology was used to ensure that the catalyst maintained good stability during long-term reactions, making it more suitable for industrial applications.
[0031] 3. In the CoMo alloy catalyst for electrocatalytic nitrate reduction reaction and its preparation method of the present invention, the multivalent states of Mo in the CoMo alloy catalyst include at least Mo 4+ Mo 5+ and Mo 6+ In this design, the doping of molybdenum not only improves the catalyst's adsorption capacity for nitrates, but also further promotes the water splitting reaction and improves the efficiency of active hydrogen generation by adjusting the different oxidation states of molybdenum. Attached Figure Description
[0032] Figure 1 This is a flowchart of the preparation method of the present invention.
[0033] Figure 2 This invention is Co 85 Mo 15 SEM morphological structure diagram.
[0034] Figure 3 This is a schematic diagram of the electrocatalyst designed in Example 1 of the present invention.
[0035] Figure 4 This is a graph showing the results of the long-term timing potential stability test in Embodiment 1 of the present invention.
[0036] Figure 5 This is a graph showing the stability test results of the water electrolysis device in Embodiment 1 of the present invention. Detailed Implementation
[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0038] Example 1:
[0039] See Figure 1 This method is used to prepare a molybdenum-doped cobalt alloy catalyst, which is particularly suitable for the reduction reaction of low-concentration 10 mM nitrate. The catalyst is prepared by electrochemical deposition of a cobalt-molybdenum alloy (CoMo), and then further electrochemical reconstruction is used to obtain reconstructed Mo-doped cobalt β-Co(OH)2 / Co. 85 Mo 15 The catalyst, and the specific steps are as follows:
[0040] Before catalyst preparation, nickel foam needs to be pretreated: foam with dimensions of 0.3 × 1.5 cm is prepared. 2 The nickel foam was placed in anhydrous ethanol and hydrochloric acid solutions in sequence and ultrasonically cleaned for 15-25 minutes each (preferably 20 minutes) to remove the surface oxide layer.
[0041] Step 1: Add 0.075-0.095 (preferably 0.085 M) molar concentration of cobalt salt, 0.005-0.025 (preferably 0.015 M) molar concentration of molybdate, 0.005-0.015 (preferably 0.01 M) molar concentration of hydroxycarboxylic acid, and 0.01-0.02 (preferably 0.015 M) molar concentration of ammonium salt to 40-60 mL (preferably 50 mL) of deionized water (DI water); continue stirring to dissolve for 15-25 minutes (preferably 20 minutes) to obtain a uniformly dispersed CoMo electrolyte; the atomic ratio of Co:Mo in the CoMo electrolyte is 0.85:0.15 (preferably also any one of 0.95:0.05, 0.9:0.1, 0.85:0.15, 0.80:0.20).
[0042] Furthermore, in this scheme, the cobalt salt includes any one or any combination of hydrated cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate;
[0043] The molybdate includes any one or any combination of hydrated sodium molybdate, anhydrous sodium molybdate, potassium molybdate, and ammonium metamolybdate.
[0044] The hydroxycarboxylic acid includes any one or any combination of citric acid, lactic acid, malic acid, and tartaric acid.
[0045] The ammonium salt includes any one or any combination of ammonium chloride, ammonium sulfate, and ammonium nitrate.
[0046] In this embodiment, the cobalt salt is preferably hydrated cobalt sulfate, but it can also be provided with Co. 2+ Other soluble cobalt salts, including but not limited to cobalt sulfate monohydrate or anhydrous cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt acetate, cobalt carbonate or cobalt hydroxide that can be dissolved under acidic conditions, etc., whose anionic and hydrated states do not affect the substantive effects of the present invention.
[0047] The preferred source of molybdenum is sodium molybdate dihydrate, but anhydrous sodium molybdate, potassium molybdate, ammonium metamolybdate, or molybdic acid can also be used to provide Mo(VI) oxygen anions under pH control conditions.
[0048] The preferred hydroxycarboxylic acid is citrate, which reduces free Co through coordination. 2+ It increases activity and stabilizes Mo(VI) anions, broadens the deposition window, and inhibits local alkalization. It can also be replaced by hydroxycarboxylic acid systems such as lactic acid / lactate and malic acid / maltate, which have suitable complexation, are easily biodegradable, and act as pH buffers. Tartaric acid (H₂Tar) or tartrate (Na₂Tar) can also be used as replacements; their α-hydroxydicarboxylic acid complexes with Co. 2+ With moderate capability, it is often used for electrodeposition leveling and suppressing side reactions.
[0049] The preferred ammonium salt is ammonium chloride. Morphology is controlled through the use of ammonium chloride electrolyte, improving film density and composition controllability. Alternatively, ammonium sulfate or ammonium nitrate ((NH4)2SO4, NH4NO3) can be used to supply NH4. + High solubility maintains ionic strength; replacement of anions avoids Cl. - Sensitive systems; sodium chloride / potassium chloride (NaCl, KCl) can also be used as a substitute, when it is necessary to retain Cl. - Morphology regulation without introducing NH4 + Use when needed.
[0050] Step 2: Using a carbon rod (graphite rod) as the counter electrode and silver / silver chloride (Ag / AgCl) filled with saturated potassium chloride (KCl) solution as the reference electrode, with an effective deposition area of 0.3 × 0.3 cm². 2 Nickel foam was used as the working electrode, with a constant current density of 1.1–1.3 A / cm². 2 (Preferred value: 1.2 A / cm) 2 Electrodeposition is performed under the following conditions (electrodeposition for 250-350 seconds, preferably 300 seconds) until a black solid deposit is formed on the working electrode to obtain a CoMo electrode sample;
[0051] Step 3: Using the CoMo electrode sample as the cathode and the carbon rod as the anode, electrolyze the sample in an H-type electrolytic cell at a constant current density of 0.95–1.5 A / cm². 2 (Preferred value: 1 A / cm) 2 The reaction is carried out for 4.5–5.5 hours, preferably 5 hours, until a black solid deposit forms on the cathode. The cathode is then removed to obtain the reconstructed Mo-doped cobalt β-Co(OH)2 / Co. 85 Mo 15 Catalyst (also represented as β-Co(OH)2 / R-Co) 85 Mo 15 R represents reconstruction.
[0052] The cathode chamber of the H-type electrolytic cell is filled with a mixed solution of potassium hydroxide (KOH) with a molar concentration of 0.5-1.5 (preferably 1 M) and potassium nitrate (KNO3) with a molar concentration of 0.05-0.15 (preferably 0.1 M) as the catholyte, and the anode chamber of the H-type electrolytic cell is filled with potassium hydroxide (KOH) with a molar concentration of 0.5-1.5 (preferably 1 M) as the anolyte.
[0053] See Figure 3 , Figure 3 To illustrate the design of the electrocatalyst, a coupled doping and reconstruction strategy was employed to selectively synthesize ammonia (NH3) via nitrate reduction. The reaction mechanism is as follows: Mo sites promote nitrate adsorption, Co sites accelerate the reduction of nitrate to nitrite, and the reconstructed Mo-doped cobalt β-Co(OH)2 phase promotes water decomposition and generates active hydrogen, thereby promoting NO2 production. - It is hydrogenated to ammonia (NH3).
[0054] In this embodiment, the stability of the long-term chronopotential of the obtained catalyst was verified.
[0055] See Figure 4 R-Co prepared by this method 85 Mo 15 The electrode was used as the cathode, and the Co2P electrode as the anode, forming a membrane electrode assembly (MEA) type alkaline electrolyzer. 1 M KOH was used as the anode electrolyte, and 1 M KOH + 10 mM KNO3 was used as the cathode electrolyte. Electrolysis was carried out at room temperature (25 °C). Experiments showed that the catalyst could withstand high current densities (660 mA / cm²). 2 It operates stably for extended periods, capable of continuous operation for over 1000 hours, making it suitable for industrial applications.
[0056] See Figure 5 The water electrolysis device operates at a constant current density of 1.0 A / cm³. 2After 100 hours of stable operation, the unit voltage is approximately 3.0 V, the Faraday efficiency (FE) remains stable at over 80%, and the NH3 yield reaches industrial-scale levels.
[0057] This scheme introduces multivalent molybdenum sites, and through the regulation of molybdenum's multivalent states, especially Mo... 4+ Mo 5+ and Mo 6+ The distribution of Mo forms a dynamically tunable electron-proton coupling system: in which, Mo 4+ Dominant NO3 - Adsorption and initial activation; Mo 5+ Mo acts as a bridge between electron transfer and intermediate hydrogenation; 6+ Enhance water-decomposing capacity to continuously supply the system with *H species.
[0058] This multi-valence synergistic mechanism significantly improves the NO3 content of the catalyst. - The adsorption, activation, and hydrogenation efficiencies of R-Co 85 Mo 15 In a low-concentration nitrate system, the catalyst still achieves a high Faradaic efficiency of 96% and an NH3 selectivity of 95%, improving the catalyst's adsorption and hydrogenation efficiency for nitrates. Furthermore, this scheme reconstructs the catalyst surface structure through an electrochemical reduction process, optimizing the catalyst's reactivity and stability, resulting in a high Faradaic efficiency (approximately 96%) and high ammonia selectivity (approximately 95%) in a low-concentration nitrate system.
[0059] Example 2:
[0060] See Figure 2 In this embodiment, a CoMo alloy catalyst is included, wherein the CoMo alloy catalyst is a black β-Co(OH)2 / Co 85 Mo 15 catalyst.
[0061] In the CoMo alloy catalyst, β-Co(OH)2 and Co 85 Mo 15 It exhibits a dual-phase heterostructure with coexisting metallic phases; the β-Co(OH)₂ phase exhibits a layered nanosheet structure, and Co… 85 Mo 15 The phase is uniformly dispersed in the form of nanocrystals or particles within or at the interface of β-Co(OH)2, and β-Co(OH)2 reacts with Co. 85 Mo 15 There is a continuous lattice transition and strain-matched interface between them. Co–O–Mo bridging bonds and strain-induced oxygen vacancy bands can form at this interface, constituting a "metal-hydroxide" type heterojunction structure; β—Co(OH)2 / Co85 Mo 15 The catalyst is not simply a change in composition of the existing CoMo system, but exhibits significant differences in structural level, lattice interactions, electron distribution, and phase interface organization. These differences result in unique physicochemical properties, providing a new structural basis for subsequent catalytic reactions.
[0062] In applications, the CoMo alloy catalyst can also be β-Co(OH)2 / Co. 95 Mo 15 β-Co(OH)2 / Co 90 Mo 10 β-Co(OH)2 / Co 80 Mo 20 Any one of them.
[0063] The CoMo alloy catalyst exhibits a high Faradaic efficiency of ≥96% and a high ammonia selectivity of ≥95% in nitrate at a concentration of 9–11 mM; the multivalent states of Mo in the CoMo alloy catalyst include at least Mo. 4+ Mo 5+ and Mo 6+ .
[0064] The Co 85 Mo 15 SEM morphological structure diagram, such as Figure 2 As shown, the catalyst exhibits a morphology composed of numerous spherical particles aggregated together. These particles are uniformly sized and distributed evenly on the substrate surface, forming a porous structure through overall packing. β-Co(OH)₂ exists in a specific β-crystal form, dispersed as nanosheets within the Co... 85 Mo 15 On the matrix, the two are combined with each other, and the particle surface is relatively flat and has a fine structure similar to "wrinkles". This structure helps to increase the specific surface area of the catalyst, providing more active sites for catalytic reaction, and also facilitates the diffusion and transport of reactants and products on the catalyst surface.
[0065] Example 3:
[0066] In this embodiment, a method for preparing a bimetallic catalyst using iron (Fe) instead of molybdenum (Mo) is provided to verify the feasibility of other transition metal doping systems.
[0067] The catalyst was electrochemically reconstructed to obtain R–Co 85 Fe 15 Its surface forms Fe–Co(OH)2 / Co 85 Fe 15 Heterogeneous structures, the specific steps are as follows:
[0068] Substrate pretreatment: Commercial nickel foam (0.3 cm × 1.5 cm) was selected and ultrasonically cleaned in anhydrous ethanol and 4.5 M hydrochloric acid solution for 20 min each to remove the surface oxide layer. After cleaning, it was rinsed with deionized water until neutral and dried at 60 °C for 30 min.
[0069] Preparation of electrodeposition solution: 0.085 M cobalt sulfate (CoSO4·7H2O), 0.015 M ferrous sulfate (FeSO4·7H2O), 0.01 M citric acid (C6H8O7), and 0.015 M ammonium chloride (NH4Cl) were added to 50 mL of deionized water and stirred under magnetic stirring for 20 min to form a homogeneous electrodeposition solution; the atomic ratio of Co:Fe in the obtained solution was approximately 85:15.
[0070] Electrochemical deposition: Electrodeposition was performed in a three-electrode system, using a graphite rod as the counter electrode, Ag / AgCl in a saturated KCl solution as the reference electrode, and nickel foam as the working electrode (effective deposition area 0.3 × 0.3 cm). 2 At a constant current density of 1.2 A / cm² 2 After reacting for 300 s, Co was obtained. 85 Fe 15 Alloy precursor;
[0071] Electrochemical reconstruction: Co 85 Fe 15 The alloy precursor was placed as the cathode in an H-type electrolytic cell, using a 1 M KOH + 0.1 M KNO3 solution as the catholyte and a 1 M KOH solution as the anolyte, and a constant current mode was used at 1 A / cm. 2 After reacting for 5 hours, the cathode was removed, rinsed with deionized water, and dried to obtain surface-hydroxylated R-Co. 85 Fe 15 catalyst.
[0072] Characterization results show that R–Co 85 Fe 15 A remodeling layer of approximately 10–30 nm, containing Co, is formed on the catalyst surface. 2+ and Fe 3+ / Fe 2+ Multiple valence states; this structure exhibits high Faraday efficiency (>80%) and stability in the electrochemical nitrate reduction reaction (NRA). Although its performance is inferior to R-Co 85 Mo 15 However, compared to existing pure Co electrodes, Fe doping increases NO3. - It enhances the adsorption and activation capabilities of NH3 while inhibiting the hydrogen evolution reaction (HER), thereby improving NH3 selectivity.
[0073] Although embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for preparing a CoMo alloy catalyst for electrocatalytic nitrate reduction reaction, characterized in that, include: Step 1: After stirring and mixing deionized water, cobalt salt, molybdate, hydroxycarboxylic acid, and ammonium salt, a CoMo electrolyte is obtained. Step 2: Using a carbon rod as the counter electrode, silver / silver chloride filled with saturated potassium chloride solution as the reference electrode, and nickel foam as the working electrode, electrodeposit CoMo electrolyte to obtain a CoMo electrode sample. Step 3: Using the CoMo electrode sample as the cathode and the carbon rod as the anode, an electrochemical reduction reaction is carried out in an H-type electrolytic cell to obtain β-Co(OH)2 / Co at the cathode. 85 Mo 15 catalyst; The cathode chamber of the H-type electrolytic cell is filled with a mixed solution of potassium hydroxide and potassium nitrate as the catholy solution, and the anode chamber of the H-type electrolytic cell is filled with potassium hydroxide as the anolyte.
2. The method for preparing the CoMo alloy catalyst for electrocatalytic nitrate reduction reaction according to claim 1, characterized in that: The process of obtaining the CoMo electrolyte specifically includes: Add 0.075–0.095 mol of cobalt salt, 0.005–0.025 mol of molybdate, 0.005–0.015 mol of hydroxycarboxylic acid, and 0.01–0.02 mol of ammonium salt to 40–60 mL of deionized water; stir continuously for 15–25 minutes to dissolve and obtain a uniformly dispersed CoMo electrolyte.
3. The method for preparing the CoMo alloy catalyst for electrocatalytic nitrate reduction reaction according to claim 1, characterized in that: The process of obtaining the CoMo electrode sample specifically includes: A carbon rod was used as the counter electrode, and silver / silver chloride filled with saturated potassium chloride solution was used as the reference electrode, with an effective deposition area of 0.3 × 0.3 cm². 2 Nickel foam was used as the working electrode, with a constant current density of 1.1–1.3 A / cm². 2 Electrodeposition was performed until a black solid deposit was formed on the working electrode, thus obtaining a CoMo electrode sample.
4. The method for preparing the CoMo alloy catalyst for electrocatalytic nitrate reduction reaction according to claim 1, characterized in that: The β-Co(OH)2 / Co obtained on the cathode 85 Mo 15 Catalysts, specifically including: Using a CoMo electrode sample as the cathode and a carbon rod as the anode, an H-type electrolytic cell was used with a constant current density of 0.95–1.5 A / cm². 2 The reaction continues until a black solid deposit forms on the cathode, yielding β-Co(OH)2 / Co. 85 Mo 15 catalyst.
5. The method for preparing the CoMo alloy catalyst for electrocatalytic nitrate reduction reaction according to claim 1, characterized in that: The cobalt salt includes any one or any combination of hydrated cobalt sulfate, cobalt nitrate, cobalt chloride, and cobalt acetate; The molybdate includes any one or any combination of hydrated sodium molybdate, anhydrous sodium molybdate, potassium molybdate, and ammonium metamolybdate. The hydroxycarboxylic acid includes any one or any combination of citric acid, lactic acid, malic acid, and tartaric acid. The ammonium salt includes any one or any combination of ammonium chloride, ammonium sulfate, and ammonium nitrate.
6. The method for preparing the CoMo alloy catalyst for electrocatalytic nitrate reduction reaction according to claim 1, characterized in that: The catholy solution is a mixed solution of potassium hydroxide with a concentration of 0.5-1.5 mol and potassium nitrate with a concentration of 0.05-0.15 mol; the anolyte is potassium hydroxide with a concentration of 0.5-1.5 mol.
7. The method for preparing the CoMo alloy catalyst for electrocatalytic nitrate reduction reaction according to claim 1, characterized in that: The atomic ratio of Co:Mo in the CoMo electrolyte includes any one of 0.85:0.15, 0.95:0.05, 0.9:0.1, 0.85:0.15, and 0.80:0.
20.
8. A CoMo alloy catalyst prepared by any one of the preparation methods of claims 1-7, characterized in that: The CoMo alloy catalyst is a black β-Co(OH)2 / Co alloy. 85 Mo 15 catalyst.
9. The CoMo alloy catalyst according to claim 8, characterized in that: In the CoMo alloy catalyst, β-Co(OH)2 and Co 85 Mo 15 It exhibits a two-phase heterogeneous structure with coexisting metallic phases; the β-Co(OH)₂ phase exhibits a layered nanosheet structure, and Co… 85 Mo 15 The phase is uniformly dispersed in the form of nanocrystals or particles within or at the interface of β-Co(OH)2, and β-Co(OH)2 reacts with Co. 85 Mo 15 There is a continuous lattice transition and strain-matched interface between them.
10. The CoMo alloy catalyst according to claim 9, characterized in that: The multivalent states of Mo in the CoMo alloy catalyst include at least Mo. 4+ Mo 5+ and Mo 6+ .