Preparation method of cobalt modified nickel hydroxide catalyst based on nickel plating waste liquid and application of prepared catalyst
By preparing a cobalt-modified nickel hydroxide catalyst, the adsorption and conversion pathways of active hydrogen and nitrogen-containing species on the catalyst surface were optimized, solving the problem of insufficient catalytic activity of pure nickel hydroxide. This enabled efficient electrochemical nitrate reduction to produce ammonia and the recycling of nickel resources, which aligns with the goal of green ammonia synthesis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTH CHINA NORMAL UNIV
- Filing Date
- 2026-02-13
- Publication Date
- 2026-05-12
AI Technical Summary
In existing technologies, the catalytic activity and selectivity of pure nickel hydroxide catalysts are insufficient to meet the actual needs of electrochemical nitrate reduction to ammonia production. Furthermore, traditional ammonia production processes are energy-intensive and have high carbon emissions, and there is a lack of effective catalyst design to optimize the adsorption and conversion pathways of active hydrogen and nitrogen-containing species.
By oxidizing nickel ethylenediaminetetraacetic acid in nickel plating waste liquid with sodium hypochlorite, a highly active precursor was induced to be deposited using nickel hydroxide, and cobalt-modified nickel hydroxide catalyst was prepared by loading cobalt nitrate through impregnation. The adsorption and conversion pathways of active hydrogen and nitrogen-containing species on the catalyst surface were optimized.
The Faraday efficiency reached 98.38% at -0.47 V (vs. RHE) and the yield reached 10.06 mgNH3 h-1 mgcat.-1 at -0.67 V (vs. RHE), which significantly improved the catalytic performance and enabled high-value recovery and utilization of nickel resources, meeting the requirements of green ammonia synthesis.
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Abstract
Description
Technical Field
[0001] This invention relates to the fields of environmental chemical engineering and electrocatalysis, specifically to a method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid and the application of the prepared catalyst. Background Technology
[0002] Ammonia is an important chemical raw material, widely used in agricultural fertilizers, chemicals, refrigeration, energy, and many other industries. Traditional ammonia production mainly relies on the Haber-Bosch process, which is energy-intensive and has a significant environmental impact, especially regarding carbon emissions under high temperature and pressure conditions. Therefore, developing alternative and sustainable ammonia production methods has become a key challenge for the global chemical industry. Electrochemical nitrate reduction to ammonia (NO3RR) has attracted attention as a promising ammonia synthesis method. This technology can not only reduce harmful nitrate levels in the environment (especially surface water) but also recover valuable nitrogen resources, upgrading them into high-value chemicals and providing a sustainable application path for nitrate recycling.
[0003] The reduction of nitrate to ammonia is a complex electrochemical process involving multi-electron (8 electrons) / multi-proton (9 protons) coupling, with relatively slow kinetics. Therefore, catalysts are often required to modulate the reaction. NO3RR ammonia synthesis typically involves two stages: the reduction of nitrate to the stable intermediate nitrite, followed by the hydrogenation of nitrite to NH3. To achieve high ammonia yields, the reaction interface must possess sufficient active hydrogen for coupling the nitrate / nitrite reduction to ammonia, while preventing the self-coupling of active hydrogen to generate hydrogen gas. Considering the need for active hydrogen to come from water splitting under alkaline conditions, NO3RR ammonia production catalysts must be rationally designed and constructed by comprehensively considering various factors.
[0004] Nickel-based materials, especially nickel hydroxide, exhibit good electrochemical activity and stability under alkaline conditions, effectively promoting water splitting, generating abundant hydrogen species on the catalyst surface, and possessing a certain adsorption / activation capacity for nitrate and intermediate species. They are considered promising catalysts for NO3RR ammonia production. However, the catalytic activity and selectivity of pure nickel hydroxide often fail to meet practical application requirements. Cobalt has been proven to be an effective auxiliary component for enhancing the reduction performance of nitrogen-containing species. Introducing cobalt is expected to optimize the adsorption strength of active hydrogen, nitrate, and intermediate species on the catalyst surface and regulate the conversion and coupling pathways of these species, thereby significantly improving the NO3RR ammonia production yield. Furthermore, the production of high-value nickel-based catalysts from nickel plating wastewater, like NO3RR for high-value ammonia production, falls under the category of green recycling and reuse of environmental waste, fully aligning with the national dual-carbon strategy goals.
[0005] In conclusion, a new technical solution is urgently needed to address the problems existing in the current technology. Summary of the Invention
[0006] Based on this, the present invention provides a method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid and the application of the prepared catalyst. The present invention first uses sodium hypochlorite to oxidize and break down the nickel ethylenediaminetetraacetic acid complex in the nickel plating waste liquid, and then uses nickel hydroxide to induce the deposition of a highly active nickel hydroxide precursor. Then, a cobalt auxiliary component is loaded onto the nickel hydroxide using an impregnation method with cobalt nitrate. After purification, a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid is obtained. When the catalyst of the present invention is used for electrochemical nitrate reduction to ammonia, the cobalt in the catalyst interacts strongly with the nickel hydroxide matrix, effectively optimizing the adsorption and conversion pathways of active hydrogen and nitrogen-containing species on the catalytic surface. This results in excellent electrocatalytic performance for nitrate reduction to ammonia, achieving a Faradaic efficiency of 98.38% at -0.47 V (vs. RHE) and a yield of 10.06 mg at -0.67 V (vs. RHE). NH3 h -1 mg cat. -1 .
[0007] This invention uses nickel plating waste liquid as the nickel source and develops a cobalt-modified nickel hydroxide composite material through a simple nickel complex breaking-precipitation-impregnation cobalt loading process. This reduces production costs while achieving high-value recycling of nickel from nickel plating waste liquid. The preparation method and the synthesized composite material have both environmental and economic benefits, with significant green and sustainable attributes. It has great application potential in the field of green ammonia synthesis and provides a new technical approach to simultaneously solve water pollution and energy chemical problems.
[0008] One object of the present invention is to provide a method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid, comprising the following steps: S1. Add sodium hypochlorite to nickel plating waste liquid containing nickel complex, heat to carry out oxidation and complex breaking treatment, and add nickel hydroxide as precipitation inducer to adjust the pH of the solution. After purification, nickel hydroxide precursor is obtained. S2. The nickel hydroxide precursor is added to water, ultrasonically dispersed, cobalt nitrate solution is added, heated and stirred for impregnation, the pH of the solution is adjusted and impregnation is continued, and the solution is purified to obtain a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid. in, The concentration of cobalt in the cobalt nitrate solution is 0.5-1.5 g·L. -1 ; The mass ratio of cobalt in the nickel hydroxide precursor and the cobalt nitrate solution is 100:5-15.
[0009] Furthermore, in step S1, the heating temperature is 25-35 ℃.
[0010] Furthermore, in step S1, the pH range of the solution is 10-12.
[0011] Further, one method for step S1 is as follows: Add 300-700 mL of nickel-plating waste liquid containing nickel complexes (nickel content 100 mg / mL) to the solution. -1 Add 3-7 mL of sodium hypochlorite solution (10 wt%) to the solution, heat at 25-35 °C for oxidation and complex breaking treatment, and add 30-50 mg of nickel hydroxide as a precipitation inducer. Adjust the pH of the solution to 10-12, and obtain the nickel hydroxide precursor by solid-liquid separation, washing and drying.
[0012] Furthermore, in step S2, the heating temperature is 50-70 ℃.
[0013] Furthermore, in step S2, the pH range of the solution is 9-10; the soaking time is 8-12 h.
[0014] Further, one method for step S2 is as follows: 100 mg of nickel hydroxide precursor is added to 20-50 mL of water and ultrasonically dispersed for 20-40 min to form a precursor suspension; 10 mL of cobalt nitrate solution (cobalt concentration is 0.5-1.5 g·L⁻¹) is added. -1 Add the precursor suspension and stir at 50-70 ℃ and 800-1200 rpm for 2 h. Adjust the pH to 9-10 with 1-3 M sodium hydroxide solution and continue stirring for 6-10 h. Then, centrifuge at 5000-10000 rpm for solid-liquid separation for 4-6 min. After washing and drying, obtain the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid.
[0015] Another object of the present invention is to provide a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid, which is prepared by the method of preparing the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid.
[0016] Another objective of this invention is to provide an application of a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid in the electrochemical reduction of nitrate to produce ammonia.
[0017] Furthermore, the application of the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid in the electrochemical reduction of nitrate to ammonia involves loading the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid onto a conductive hydrophilic carbon paper substrate as a working electrode, and carrying out the electrocatalytic reduction of nitrate to ammonia reaction in an alkaline electrolyte containing nitrate ions.
[0018] Furthermore, the potential of the electrocatalytic reduction reaction is from -0.27 V to -0.67 V (vs. RHE).
[0019] Furthermore, the alkaline electrolyte is a mixed solution of KNO3 and KOH; in the alkaline electrolyte, the concentration of KNO3 is 0.05-0.2 M and the concentration of KOH is 1-3 M.
[0020] The present invention has the following beneficial effects: This invention provides a method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid and its application. First, the nickel ethylenediaminetetraacetic acid (EDTA) in the nickel plating waste liquid is broken down by oxidation with sodium hypochlorite, and a highly active nickel hydroxide precursor is induced to deposit using nickel hydroxide. Then, a cobalt auxiliary component is loaded onto the nickel hydroxide using an impregnation method with cobalt nitrate. After purification, the cobalt-modified nickel hydroxide catalyst based on the nickel plating waste liquid is obtained. When the catalyst of this invention is used for the electrochemical reduction of nitrate to ammonia, the cobalt in the catalyst interacts strongly with the nickel hydroxide matrix, effectively optimizing the adsorption and conversion pathways of active hydrogen and nitrogen-containing species on the catalytic surface, thus exhibiting excellent electrocatalytic performance for the reduction of nitrate to ammonia. The catalyst with the best performance is prepared when the mass ratio of cobalt loading to nickel hydroxide precursor is 1:10, achieving a Faradaic efficiency of 98.38% at -0.47 V (vs. RHE) and a yield of 10.06 mg at -0.67 V (vs. RHE). NH3 h -1 mg cat. -1 .
[0021] This invention utilizes cobalt nitrate to prepare a cobalt-modified nickel hydroxide catalyst based on nickel plating wastewater. The cobalt-modified nickel hydroxide catalyst prepared based on this cobalt salt has a large number of high-performance catalytic sites. When the mass ratio of cobalt loading to nickel hydroxide precursor is 100:5-15, a catalyst with a small particle morphology can be formed. The catalyst with this morphology can provide sufficient effective sites for catalytic nitrate reduction. At the same time, the introduction of cobalt effectively optimizes the adsorption intensity of active hydrogen, nitrate, and intermediate species on the catalyst surface and controllably adjusts the conversion and coupling pathways of each species, thereby significantly improving the catalytic performance of nickel hydroxide electrochemical nitrate reduction to ammonia. Attached Figure Description
[0022] Figure 1 The X-ray diffraction (XRD) patterns of the catalysts in Examples 1-3 and the comparative examples are shown in comparison.
[0023] Figure 2 The energy scattering (EDS) spectra and EDS plots of the comparative catalysts are shown. in, Figure 2 (a) shows a SEM image of the comparative catalyst; Figure 2(b) shows the EDS surface scan of Ni element in the comparative catalyst; Figure 2 (c) shows the EDS surface scan of O element in the comparative catalyst.
[0024] Figure 3 The SEM and EDS images of the catalyst in Example 2 are shown. in, Figure 3 (a) shows a SEM image of the catalyst in Example 2; Figure 3 (b) shows the EDS surface scan of Ni element in the catalyst of Example 2; Figure 3 (c) shows the EDS surface scan of the O element in the catalyst of Example 2; Figure 3 (d) shows the EDS surface scan of Co element in the catalyst of Example 2.
[0025] Figure 4 The full X-ray photoelectron spectroscopy (XPS) spectra and high-resolution XPS plots of Ni elemental catalysts of Example 2 and the comparative example are shown. in, Figure 4 (a) shows the XPS full spectrum of the catalysts in Example 2 and the comparative example; Figure 4 (b) shows the Ni element high-resolution XPS plots of the catalysts of Example 2 and the comparative example.
[0026] Figure 5 Raman spectra of the catalysts in Example 2 and the comparative example are shown.
[0027] Figure 6 The diagram shows a comparison of the performance of nitrate reduction to ammonia production by the catalysts of Examples 1-3 and the comparative examples.
[0028] Figure 7 The graph shows a comparison of the performance of the catalyst in Example 2 for nitrate reduction to ammonia at different voltages. Detailed Implementation
[0029] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.
[0030] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.
[0031] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values varying according to the desired performance to be obtained according to the invention.
[0032] In this invention, unless otherwise specified, all raw materials used are commercially available products in the art, and all operations are performed under room temperature and atmospheric pressure conditions.
[0033] Unless otherwise specified, all water used in this invention is deionized water.
[0034] Example 1 A method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid includes the following steps: S1. Take 500 mL of simulated nickel plating waste liquid containing nickel ethylenediaminetetraacetate (nickel concentration of 100 mg / mL). -1 Under stirring conditions, 5 mL of sodium hypochlorite aqueous solution (10 wt%) was added and oxidized and broken down at 30 °C for 3 h; at the same time, 30 mg of nickel hydroxide was added as a precipitation inducer to induce nickel hydroxide precipitation. The pH was adjusted to 11 with 1 M sodium hydroxide solution, stirred, allowed to stand, filtered, and the precipitate was washed with deionized water until the filtrate was neutral. After drying and grinding, the nickel hydroxide precursor was obtained. S2. Disperse 100 mg of the nickel hydroxide precursor in 30 mL of deionized water and sonicate for 30 min to form a homogeneous precursor suspension; prepare 10 mL of cobalt nitrate aqueous solution (cobalt concentration is 0.5 g·L⁻¹). -1 The cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid was slowly added dropwise at a rate of 1 drop / second to a vigorously stirred precursor suspension. The mixture was stirred at 60 °C and 1000 rpm for 2 h. Then, 1 M sodium hydroxide solution was added to adjust the pH to 9.5, and stirring was continued for 8 h. Finally, solid-liquid separation was performed by centrifugation at 8500 rpm for 5 min. The obtained solid product was washed three times with deionized water and anhydrous ethanol and dried at 60 °C for 10 h to obtain the cobalt-modified nickel hydroxide catalyst, denoted as Co. 0.05 Ni(OH)2.
[0035] Example 2 A method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid. The difference between this embodiment and Example 1 is that the concentration of the cobalt nitrate aqueous solution is adjusted to a cobalt concentration of 1 g·L⁻¹. -1 A cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid was obtained, denoted as Co. 0.1 Ni(OH)2.
[0036] Example 3 A method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid. The difference between this embodiment and Example 1 is that the concentration of the cobalt nitrate aqueous solution is adjusted to a cobalt concentration of 1.5 g·L⁻¹. -1 A cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid was obtained, denoted as Co. 0.15 Ni(OH)2.
[0037] Comparative Example The nickel hydroxide precursor prepared in step S1 of Example 1 is denoted as Ni(OH)2.
[0038] Figure 1 The XRD patterns of the catalysts in Examples 1-3 and the comparative examples are shown.
[0039] Depend on Figure 1 It can be seen that the Co prepared in Examples 1-3 0.05 Ni(OH)2, Co 0.1 Ni(OH)2, Co 0.15 The structures of Ni(OH)2 and Ni(OH)2 prepared in the comparative example were characterized by XRD. The comparative analysis showed that the cobalt loading operation of the impregnation method used in this invention did not change the bulk structure of Ni(OH)2.
[0040] Figure 2 SEM and EDS images of the comparative catalysts are shown. in, Figure 2 (a) shows a SEM image of the comparative catalyst; Figure 2 (b) shows the EDS surface scan of Ni element in the comparative catalyst; Figure 2 (c) shows the EDS surface scan of O element in the comparative catalyst.
[0041] Figure 3 The SEM and EDS images of the catalyst in Example 2 are shown. in, Figure 3 (a) shows a SEM image of the catalyst in Example 2; Figure 3(b) shows the EDS surface scan of Ni element in the catalyst of Example 2; Figure 3 (c) shows the EDS surface scan of the O element in the catalyst of Example 2; Figure 3 (d) shows the EDS surface scan of Co element in the catalyst of Example 2.
[0042] The Co obtained in Example 2 0.1 Ni(OH)₂ and the Ni(OH)₂ prepared in the comparative example were characterized by elemental distribution by EDS. Figure 2 (a)-2(c) show that Ni and O are evenly distributed in the Ni(OH)2 control sample; Figure 3 (a)-3(d) show that Ni, Co, and O are evenly distributed in Co 0.1 In the Ni(OH)2 sample, combined with XRD characterization results, it can be inferred that Ni(OH)2 and Co have been successfully prepared. 0.1 Ni(OH)2 sample.
[0043] Compared to the comparative catalyst, the catalyst particle size of Example 2 decreased and its morphology changed significantly after the introduction of cobalt nitrate, thereby providing a sufficient number of effective catalytic sites for catalytic applications.
[0044] Figure 4 XPS full spectrum and high-resolution XPS plot of Ni element of catalysts of Example 2 and comparative example are shown; in, Figure 4 (a) shows the XPS full spectrum of the catalysts in Example 2 and the comparative example; Figure 4 (b) shows the Ni element high-resolution XPS plots of the catalysts of Example 2 and the comparative example.
[0045] The Co obtained in Example 2 0.1 Ni(OH)₂ and the Ni(OH)₂ prepared in the comparative example were characterized by elemental composition and state using XPS. Figure 4 (a) It can be seen that Ni and O signals were observed in the Ni(OH)2 control sample, while Co signals were observed in the control sample. 0.1 The presence of Ni, Co, and O signals in the Ni(OH)₂ sample further confirms the successful preparation of Ni(OH)₂ and Co. 0.1 Ni(OH)₂ sample. From Figure 4 (b) It can be seen that, compared to the Ni(OH)2 control sample, Co 0.1The high-resolution Ni XPS of the Ni(OH)2 sample showed a significant shift, which proves that the introduced Co auxiliary component interacted strongly with the background Ni(OH)2 and modulated the electronic structure of Ni.
[0046] Figure 5 Raman diagrams of the catalysts in Example 2 and the comparative example are shown.
[0047] The Co obtained in Example 2 0.1 Ni(OH)₂ and the Ni(OH)₂ prepared in the comparative example were characterized by Raman spectroscopy. Figure 5 It can be seen that, compared to the Ni(OH)2 control sample, Co 0.1 The Ni-O and Ni-OH bonds in the Ni(OH)2 sample underwent a significant blue shift, further confirming that the introduced Co auxiliary component interacted strongly with the background Ni(OH)2, regulating the electronic structure of Ni, which is consistent with the XPS conclusions.
[0048] Test Example 1 The electrocatalytic nitrate reduction performance of Examples 1-3 and the comparative example was tested.
[0049] Test method: 10 mg of catalyst, 480 μL of deionized water, 1440 μL of anhydrous ethanol, and 80 μL of Nafion solution (5 wt%) were ultrasonically mixed for 1 h to prepare a homogeneous ink slurry. 200 μL of the ink slurry was then uniformly coated onto a 1×1.5 cm plate. 2 On carbon paper, after baking and drying, it serves as the working electrode with a working area of 1×1 cm. 2 An H-type electrolytic cell was used, with a mixed solution of 0.1 M KNO3 and 1 M KOH as the electrolyte. The anode and cathode volumes were each 25 mL. A platinum sheet was used as the counter electrode, and an Hg / HgO electrode was used as the reference electrode. After electrolysis at a constant potential for 1 h, a fixed volume of electrolyte was diluted to 10 mL. The ammonia concentration in the electrolyte was quantified using indophenol blue spectrophotometry, and the ammonia yield and Faraday efficiency were calculated.
[0050] Ammonia yield calculation formula: Among them, c NH3 The measured concentration of ammonia (mol / L) -1 V is the volume of electrolyte (L), t is the electrolysis time (s), and m is the mass of catalyst loaded on carbon paper (g).
[0051] Formula for calculating the ammonia Faraday efficiency: Among them, c NH3The measured concentration of ammonia (mol / L) -1 V is the volume of the electrolyte (L), and F is the Faraday constant (96485 C mol). -1 Q is the total charge passing through the electrodes, FE NH3 The ammonia Faraday efficiency.
[0052] Test results are as follows Figure 6 As shown.
[0053] Figure 6 The diagram shows a comparison of the performance of nitrate reduction to ammonia production by the catalysts of Examples 1-3 and the comparative examples.
[0054] Depend on Figure 6 It can be seen that the ammonia yield and Faraday efficiency of the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid prepared in Examples 1-3 are better than those of the comparative examples. Among them, the Co prepared in Example 2... 0.1 Ni(OH)2 has the best performance.
[0055] Test Example 2 The ammonia yield and Faraday efficiency of electrocatalytic nitrate reduction to ammonia production at different potentials in Example 2 were tested.
[0056] Test method: The Co prepared in Example 2 was used as a test subject. 0.1 Using Ni(OH)₂ as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode, a three-electrode system was used. Electrolysis was performed for 1 h at constant potentials at -0.27 V, -0.37 V, -0.47 V, -0.57 V, and -0.67 V, respectively, using a mixed solution of 0.1 M KNO₃ and 1 M KOH as the electrolyte. The ammonia concentration in the electrolyte was then quantified using indophenol blue spectrophotometry, and the ammonia yield and Faraday efficiency were calculated.
[0057] Test results are as follows Figure 7 As shown.
[0058] Figure 7 The graph shows a comparison of the performance of the catalyst in Example 2 for nitrate reduction to ammonia at different voltages.
[0059] Depend on Figure 7 It can be seen that the Co prepared in Example 2 0.1 The optimal Faradaic efficiency for ammonia synthesis from Ni(OH)₂ was 98.38% at -0.47 V (vs. RHE), and the optimal ammonia yield was 10.06 mg at -0.67 V (vs. RHE). NH3 h -1 mg cat. -1 .
[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0061] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating wastewater, characterized in that, Includes the following steps: S1. Add sodium hypochlorite to nickel plating waste liquid containing nickel complex, heat to carry out oxidation and complex breaking treatment, and add nickel hydroxide as precipitation inducer to adjust the pH of the solution. After purification, nickel hydroxide precursor is obtained. S2. The nickel hydroxide precursor is added to water, ultrasonically dispersed, cobalt nitrate solution is added, heated and stirred for impregnation, the pH of the solution is adjusted and impregnation is continued, and the solution is purified to obtain a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid. in, The concentration of cobalt in the cobalt nitrate solution is 0.5-1.5 g·L. -1 ; The mass ratio of cobalt in the nickel hydroxide precursor and the cobalt nitrate solution is 100:5-15.
2. The method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid according to claim 1, characterized in that, In step S1, the heating temperature is 25-35 ℃.
3. The preparation method of the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid according to claim 1, characterized in that, In step S1, the pH range of the solution is 10-12.
4. The method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid according to claim 1, characterized in that, In step S2, the heating temperature is 50-70 ℃.
5. The method for preparing a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid according to claim 1, characterized in that, In step S2, the pH range of the solution is 9-10.
6. A cobalt-modified nickel hydroxide catalyst based on nickel plating wastewater, characterized in that, It is prepared by the method for preparing cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid according to any one of claims 1 to 5.
7. The application of a cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid as described in claim 6 in the electrochemical reduction of nitrate to produce ammonia.
8. The application of the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid according to claim 7 in the electrochemical reduction of nitrate to ammonia, characterized in that, The cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid was loaded onto a conductive hydrophilic carbon paper substrate as a working electrode, and an electrocatalytic reduction reaction of nitrate to ammonia was carried out in an alkaline electrolyte containing nitrate ions.
9. The application of the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid according to claim 8 in the electrochemical reduction of nitrate to ammonia, characterized in that, The potential for the electrocatalytic reduction reaction is from -0.27 V to -0.67 V (vs. RHE).
10. The application of the cobalt-modified nickel hydroxide catalyst based on nickel plating waste liquid according to claim 8 in the electrochemical reduction of nitrate to ammonia, characterized in that, The alkaline electrolyte is a mixed solution of KNO3 and KOH; in the alkaline electrolyte, the concentration of KNO3 is 0.05-0.2 M and the concentration of KOH is 1-3 M.