High-entropy perovskite hydroxide, preparation method thereof and application of high-entropy perovskite hydroxide in electro-catalysis of nitrate to synthesize ammonia
By optimizing electron transport performance using high-entropy perovskite hydroxide electrocatalysts, the problems of slow reaction kinetics and competition with hydrogen evolution reaction in the electrochemical conversion of NO3- were solved, achieving efficient reduction of NO3- to NH3 and providing a sustainable pathway for resource recovery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LIAONING UNIVERSITY
- Filing Date
- 2026-04-01
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies suffer from slow reaction kinetics and competitive hydrogen evolution reactions during the electrochemical conversion of NO3-, which limit the Faraday efficiency of ammonia synthesis and prevent the effective elimination of nitrogen pollutants and resource recovery.
High-entropy perovskite hydroxides (such as (ZnMnCoNiCu)Sn(OH)6, etc.) are used as electrocatalysts to perform electrocatalytic nitrate reduction by loading them on carbon cloth. Their unique electronic structure and multifunctional active sites are utilized to optimize electron transport performance.
It achieves efficient NO3- to NH3 reduction with a maximum Faraday efficiency of 98.16% and a yield of 5.12 mg h-1 mgcat.-1, improving the generation and utilization of active hydrogen, enhancing the selectivity of NO3RR, and providing a sustainable pathway to eliminate high-oxidation-state nitrogen pollutants.
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Figure CN122079262A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-entropy perovskite hydroxide technology, specifically relating to a high-entropy perovskite hydroxide, its preparation method, and its application in electrocatalytic nitrate synthesis of ammonia. Background Technology
[0002] The global nitrogen cycle imbalance has been exacerbated by the uncontrolled discharge of industrial and agricultural wastewater and nitrate slag runoff, leading to severe water pollution and threatening ecological security. Nitrate (NO3) - As a typical high-oxidation-state nitrogen pollutant, nitrogen has exceeded the drinking water limit (<10 mgN / L) set by the World Health Organization in many water bodies, posing a potential threat to human health through processes such as methemoglobinemia. This urgently requires pollutant removal technologies that can simultaneously eliminate nitrogen pollutants and achieve resource recovery. However, current methods face significant challenges: (1) NO3 - The electrochemical conversion involves complex multi-electron / proton transfer processes, resulting in slow reaction kinetics; (2) the competitive hydrogen evolution reaction limits the Faraday efficiency of ammonia synthesis. To address these issues, it is crucial to develop advanced catalysts with customized electronic structures and multifunctional active sites. High-entropy materials (HEMs) have become promising candidates due to their unique "cocktail effect" and structural stability, which makes it possible to construct diverse active centers and optimize electron transport performance. Among them, high-entropy perovskite hydroxides (HEPHs) have shown great potential in electrocatalysis due to their tunable crystal structure and high electron mobility. Summary of the Invention
[0003] In order to solve the technical problems existing in the prior art, the purpose of this invention is to provide a high-entropy perovskite hydroxide with simple preparation method, stable structure and high catalytic efficiency, as well as its preparation method and application.
[0004] To achieve the above-mentioned objective, the technical solution adopted by the present invention is: a high-entropy perovskite hydroxide, wherein the high-entropy perovskite hydroxide is ASn(OH)6, wherein A is one or more of Zn, Mn, Co, Ni and Cu.
[0005] The aforementioned high-entropy perovskite hydroxide is (ZnMnCoNiCu)Sn(OH)6, (ZnMn)Sn(OH)6, (ZnCo)Sn(OH)6, (ZnNi)Sn(OH)6, (ZnCu)Sn(OH)6, and ZnSn(OH)6.
[0006] A method for preparing high-entropy perovskite hydroxide includes the following steps:
[0007] 1) Dissolve divalent metal chloride and sodium citrate in water, and dissolve tetravalent tin chloride in ethanol. Mix the two solutions together and stir.
[0008] 2) Under heating conditions, sodium hydroxide solution was quickly added. After 1 hour, the precipitate was collected by centrifugation, washed several times, and dried to obtain the target product.
[0009] In the above-mentioned method for preparing a high-entropy perovskite hydroxide, in step 1), the divalent metal chloride salt is one or more of manganese chloride, cobalt chloride, nickel chloride, copper chloride, and zinc chloride.
[0010] In the above-mentioned method for preparing a high-entropy perovskite hydroxide, in step 1), the total number of moles of divalent metal chlorides: the number of moles of sodium citrate: the number of moles of tetravalent tin chloride = 1:1:1. When there are multiple divalent metal chlorides, each divalent metal chloride is added in an equal molar ratio.
[0011] In the above-mentioned method for preparing a high-entropy perovskite hydroxide, step 2) involves heating at 80°C.
[0012] In the above-mentioned method for preparing a high-entropy perovskite hydroxide, in step 2), the concentration of the sodium hydroxide solution is 2 M.
[0013] The above-mentioned high-entropy perovskite hydroxide is used as an electrocatalyst in the electrocatalytic reduction of nitrate.
[0014] The above application is carried out as follows: high-entropy perovskite hydroxide is loaded on carbon cloth as the working electrode, Ag / AgCl is the reference electrode, platinum sheet is the counter electrode, and a mixed solution of 1.0 M KOH and 0.1 M KNO3 is used for electrocatalytic reduction of nitrate.
[0015] The beneficial effects of this invention are:
[0016] 1. The high-entropy perovskite hydroxide provided by this invention exhibits high catalytic efficiency, with the highest NH3 Faradaic efficiency reaching 98.16% (relative to RHE of -0.4 V), and a yield of 5.12 mg h. -1 mg cat. -1 .
[0017] 2. The high-entropy perovskite hydroxide provided by this invention has a stronger ability to generate, transfer and utilize active hydrogen, ultimately improving the selectivity of NO3RR.
[0018] 3. The high-entropy perovskite hydroxide prepared by the method of this invention provides a sustainable way to eliminate nitrogen pollutants in high oxidation states and generate high-value ammonia. Attached Figure Description
[0019] Figure 1 It is the structural model of A5Sn(OH)6.
[0020] Figure 2 The images show the XRD patterns of (a) ZnSn(OH)6, (b) ZnSn(OH)6-A5Sn(OH)6, (c) a magnified XRD pattern of ZnSn(OH)6-A5Sn(OH)6, and (d) Rievteld refined XRD pattern of A5Sn(OH)6 prepared in Example 1.
[0021] Figure 3 These are SEM images of ZnSn(OH)6-A5Sn(OH)6 prepared in Example 1, where (a) is a SEM image of ZnSn(OH)6, (b) is a SEM image of (ZnMn)Sn(OH)6, (c) is a SEM image of (ZnCo)Sn(OH)6, (d) is a SEM image of (ZnNi)Sn(OH)6, (e) is a SEM image of (ZnCu)Sn(OH)6, and (f) is a SEM image of A5Sn(OH)6.
[0022] Figure 4 The images shown are (a) and (b) TEM images of A5Sn(OH)6 prepared in Example 1, (c) HRTEM image of A5Sn(OH)6, and (d) SAED image of A5Sn(OH)6.
[0023] Figure 5 These are high-angle annular dark-field images and EDS surface scans of each element of A5Sn(OH)6 prepared in Example 1.
[0024] Figure 6 This is the LSV diagram of A5Sn(OH)6 in Example 2.
[0025] Figure 7 These are comparison charts of ammonia yield of (a) ZnSn(OH)6-A5Sn(OH)6 and (b) Faraday efficiency of ZnSn(OH)6-A5Sn(OH)6 in Example 2.
[0026] Figure 8 The NH3 Faraday efficiency and NO2 of A5Sn(OH)6 in Example 2 are... - Faraday efficiency comparison chart.
[0027] Figure 9 In Example 2, (ZnCu)Sn(OH)6 and A5Sn(OH)6LaB5O3 are electrically charged in (a) containing and (b) not containing NO3. - In-situ impedance diagram of 1 M KOH solution. Detailed Implementation
[0028] Example 1: High-entropy perovskite hydroxide
[0029] I. High-entropy perovskite hydroxide (ZnMnCoNiCu)Sn(OH)6
[0030] The preparation method is as follows:
[0031] 0.4 mmol of MnCl₂·4H₂O, 0.4 mmol of CoCl₂·6H₂O, 0.4 mmol of NiCl₂·6H₂O, 0.4 mmol of CuCl₂·2H₂O, 0.4 mmol of ZnCl₂, and 2 mmol of sodium citrate (C₆H₅Na₃O₇) were dissolved in 70 mL of deionized water. 2 mmol of SnCl₄·5H₂O was dissolved in 10 mL of ethanol. The two solutions were mixed and stirred for 30 minutes. Under an oil bath at 80 °C, 10 mL of 2 M NaOH solution was rapidly added. After 1 h, the precipitate was collected by centrifugation, washed several times with ethanol and deionized water, and then dried at 60 °C to obtain (ZnMnCoNiCu)Sn(OH)₆, denoted as A₅Sn(OH)₆.
[0032] II. Binary perovskite hydroxide ((ZnMn)Sn(OH)6)
[0033] The preparation method is as follows:
[0034] 1 mmol of MnCl₂·4H₂O, 1 mmol of ZnCl₂, and 2 mmol of C₆H₅Na₃O₇ were dissolved in 70 mL of deionized water. 2 mmol of SnCl₄·5H₂O was dissolved in 10 mL of ethanol. The two solutions were mixed and stirred for 30 minutes. 10 mL of 2 M NaOH solution was rapidly added in an oil bath at 80 °C. After 1 h, the precipitate was collected by centrifugation, washed several times with ethanol and deionized water, and then dried at 60 °C to obtain (ZnMn)Sn(OH)₆.
[0035] III. Binary perovskite hydroxide ((ZnCo)Sn(OH)6)
[0036] The preparation method is as follows:
[0037] 1 mmol of CoCl₂·6H₂O, 1 mmol of ZnCl₂, and 2 mmol of C₆H₅Na₃O₇ were dissolved in 70 mL of deionized water. 2 mmol of SnCl₄·5H₂O was dissolved in 10 mL of ethanol. The two solutions were mixed and stirred for 30 minutes. 10 mL of 2 M NaOH solution was rapidly added in an oil bath at 80 °C. After 1 h, the precipitate was collected by centrifugation, washed several times with ethanol and deionized water, and then dried at 60 °C to obtain (ZnCo)Sn(OH)₆.
[0038] IV. Binary perovskite hydroxide ((ZnNi)Sn(OH)6)
[0039] The preparation method is as follows:
[0040] 1 mmol of NiCl₂·6H₂O, 1 mmol of ZnCl₂, and 2 mmol of C₆H₅Na₃O₇ were dissolved in 70 mL of deionized water. 2 mmol of SnCl₄·5H₂O was dissolved in 10 mL of ethanol. The two solutions were mixed and stirred for 30 minutes. 10 mL of 2 M NaOH solution was rapidly added in an oil bath at 80 °C. After 1 h, the precipitate was collected by centrifugation, washed several times with ethanol and deionized water, and then dried at 60 °C to obtain (ZnNi)Sn(OH)₆.
[0041] V. Binary perovskite hydroxide ((ZnCu)Sn(OH)6)
[0042] The preparation method is as follows:
[0043] 1 mmol of CuCl₂·2H₂O, 1 mmol of ZnCl₂, and 2 mmol of C₆H₅Na₃O₇ were dissolved in 70 mL of deionized water. 2 mmol of SnCl₄·5H₂O was dissolved in 10 mL of ethanol. The two solutions were mixed and stirred for 30 minutes. 10 mL of 2 M NaOH solution was rapidly added in an oil bath at 80 °C. After 1 h, the precipitate was collected by centrifugation, washed several times with ethanol and deionized water, and then dried at 60 °C to obtain (ZnCu)Sn(OH)₆.
[0044] VI. Perovskite hydroxide (ZnSn(OH)6)
[0045] The preparation method is as follows:
[0046] 2 mmol of ZnCl₂ and 2 mmol of C₆H₅Na₃O₇ were dissolved in 70 mL of deionized water. 2 mmol of SnCl₄·₅H₂O was dissolved in 10 mL of ethanol. The two solutions were mixed and stirred for 30 minutes. 10 mL of 2 M NaOH solution was rapidly added in an oil bath at 80 °C. After 1 h, the precipitate was collected by centrifugation, washed several times with ethanol and deionized water, and then dried at 60 °C to obtain ZnSn(OH)₆.
[0047] VII. Test Results
[0048] Figure 2 These are the XRD patterns of (a) ZnSn(OH)6 prepared in this embodiment, (b) XRD patterns of ZnSn(OH)6, (ZnMn)Sn(OH)6, (ZnCo)Sn(OH)6, (ZnNi)Sn(OH)6, (ZnCu)Sn(OH)6, and A5Sn(OH)6, (c) magnified XRD patterns of ZnSn(OH)6, (ZnMn)Sn(OH)6, (ZnCo)Sn(OH)6, (ZnNi)Sn(OH)6, (ZnCu)Sn(OH)6, and A5Sn(OH)6, and (d) Rievteld refined XRD pattern of A5Sn(OH)6. First, the crystal structure and phase purity of the samples were studied by powder X-ray diffraction (XRD). Figure 2 As shown in (b), all diffraction peaks of the synthesized A5Sn(OH)6 can be correlated with the perovskite hydroxide (ZnSn(OH)6) phase (PDF#73-2384). Figure 2 (a) Precise correspondence. The main diffraction peaks correspond to 2θ angles of 19.7°, 22.8°, 32.4°, 36.4°, 38.2°, 40.0°, 43.4°, 46.5°, 49.5°, 51.0°, 57.9°, 61.7°, 67.9°, 71.5°, 72.7°, and 77.3°, respectively, corresponding to the (1 1 1), (2 0 0), (2 2 0), (0 1 3), (3 11), (2 2 2), (3 2 1), (4 0 0), (4 1 1), (3 3 1), (4 2 2), (5 1 1), (4 4 0), (1 3 5), (44 2), and (6 2 0) crystal planes. These clear diffraction peaks reflect the high crystallinity of the sample, and the absence of other impurity diffraction peaks indicates that the synthesized A5Sn(OH)6 has good phase purity. Figure 3As can be observed in the extended XRD spectrum shown in (c), the lattice shrinks as the radius of the introduced metal ions gradually decreases, thus shifting the main XRD diffraction peak to a higher angle. However, due to the "compensation effect" between the metal ion radius and its disordered arrangement, the position of the main XRD diffraction peak of HEPH A5Sn(OH)6 remains close to that of ZnSn(OH)6. Based on the Rietveld optimization results of the XRD spectral data of the A5Sn(OH)6 sample, its corresponding perovskite hydroxide crystal structure is as follows: Figure 2 (d) As shown in the illustration. The simulated XRD spectra of the five metal elements at a 1 / 3 scale are in perfect agreement with the experimental data (Rp = 7.24%), which confirms the successful synthesis of the high-entropy perovskite hydroxide A5Sn(OH)6.
[0049] Figure 3 These are SEM images of ZnSn(OH)6, (ZnMn)Sn(OH)6, (ZnCo)Sn(OH)6, (ZnNi)Sn(OH)6, (ZnCu)Sn(OH)6, and A5Sn(OH)6 prepared in this embodiment. The microstructure of this series of perovskite hydroxides was analyzed using scanning electron microscopy (SEM), and the results showed that they all exhibited regular nanocubic structures.
[0050] Figure 4 These are TEM images of (a)-(b) A5Sn(OH)6 prepared in this embodiment, HRTEM image of (c) A5Sn(OH)6, and SAED image of (d) A5Sn(OH)6. The surface morphology and microstructure of A5Sn(OH)6 were analyzed by transmission electron microscopy (TEM). The TEM results show that A5Sn(OH)6 also exhibits a nanocubic morphology. Figure 3 (a)-(b). High-resolution transmission electron microscopy (HRTEM) images show that the interplanar spacing of A5Sn(OH)6 is approximately 0.271 nm, corresponding to the (2 2 0) crystal plane of ZnSn(OH)6. Figure 3 (c) Selected area electron diffraction (SAED) revealed a regular diffraction lattice array, confirming the high crystallinity of the perovskite hydroxide.
[0051] Figure 5 These are high-angle annular dark-field images and EDS surface scans of A5Sn(OH)6 prepared in this embodiment. Energy-dispersive spectroscopy (EDS) elemental imaging shows that all elements, including O, Mn, Co, Ni, Cu, Zn, and Sn, are uniformly distributed on the nanocubes.
[0052] Example 2: Application of A5Sn(OH)6 as an electrocatalyst in the electrocatalytic reduction of nitrate.
[0053] Method: The high-entropy perovskite hydroxide A5Sn(OH)6 prepared in Example 1 was loaded onto carbon cloth as the working electrode, Ag / AgCl was used as the reference electrode, and a platinum sheet was used as the counter electrode. The electrolyte was a mixed solution of 1.0 M KOH and 0.1 M KNO3.
[0054] Preparation of the working electrode: 4 mg of catalyst was dispersed in a mixture of 50 μL of 5 wt% Nafion solution, 250 μL of ultrapure water, and 250 μL of ethanol. The mixture was sonicated for 30 minutes. Then, 50 μL of the slurry was drop-coated onto a 1×2 cm carbon cloth (coated on both sides), with an actual immersion area of 1 cm². 2 It was then dried at 60°C. The catalyst loading was approximately 0.5 mg / cm³. 2 Before using carbon cloth, it needs to be ultrasonically cleaned with ethanol and ultrapure water in sequence, then soaked in concentrated nitric acid for 30 minutes, and finally cleaned several times with ultrapure water and ethanol, and dried before use.
[0055] The electrocatalytic performance of the prepared catalyst for the nitrate reduction reaction (NO3RR) was systematically evaluated using a three-electrode system. The NO3RR activity of HEPH A5Sn(OH)6 in 1.0 M KOH and 0.1 M KNO3 solutions was investigated using LSV curves. Figure 6 As shown, the catalyst current density is mainly generated by NO3RR rather than hydrogen evolution reaction (HER), indicating that NO3RR plays a dominant role.
[0056] Chronoamperometry revealed that the NH3 yield of all samples increased with increasing potential, with the following order: A5Sn(OH)6 > (ZnCu)Sn(OH)6 > (ZnNi)Sn(OH)6 > (ZnCo)Sn(OH)6 > (ZnMn)Sn(OH)6 > ZnSn(OH)6. A5Sn(OH)6 exhibited the highest NH3 yield, reaching 5.12 mg h⁻¹ at -0.6 V (vs. RHE). -1 mg cat. -1 ( Figure 7(a)). Meanwhile, the Faraday efficiencies of (ZnCo)Sn(OH)6, (ZnNi)Sn(OH)6, (ZnCo)Sn(OH)6, and A5Sn(OH)6 still follow the above order. The higher local Faraday efficiencies of (ZnMn)Sn(OH)6 and ZnSn(OH)6 are due to the lower current density within this potential window. Notably, the Faraday efficiency of A5Sn(OH)6 exhibits a volcano-shaped curve, reaching a maximum of 98.16% at -0.4 V (vs. RHE), and the Faraday efficiency is greater than 80% at all potentials. Figure 7 (b)).
[0057] In addition, NO2 - The Faraday efficiency of the catalyst for NO2 and N2H4 was studied. - The Faraday efficiency is very low, and no N2H4 is generated, indicating that the ammonia selectivity of A5Sn(OH)6 is very good. Figure 8 ).
[0058] The reaction kinetics of water dissociation and nitrate activation were investigated by in-situ electrochemical impedance spectroscopy (EIS). In the Bode phase diagram, the intensity of the phase angle peaks reflected the charge transfer rate at the reaction interface, while the position of the phase angle peaks indicated the water dissociation process. The low-frequency and mid-frequency peaks corresponded to the Volmer and Heyrovsky steps of water dissociation, respectively. In the absence of nitrate, two low-frequency and mid-frequency peaks of A5Sn(OH)6 were observed in the potential range of -0.2 V to -0.6 V (vs. RHE). With increasing potential, both peaks shifted towards the high-frequency region. Figure 9 (a) Compared to A5Sn(OH)6, (ZnCu)Sn(OH)6 exhibits a lower frequency peak position and higher peak intensity at the same potential, indicating that A5Sn(OH)6 has a faster charge transfer rate and faster kinetics during water dissociation. Upon addition of nitrate ions, the low-frequency peak of A5Sn(OH)6 disappears, while the low-frequency peak of (ZnCu)Sn(OH)6 is retained. Their mid-frequency peaks both shift towards the high-frequency region. Figure 9 (b) However, the shift range of (ZnCu)Sn(OH)6 is smaller than that of A5Sn(OH)6, and the peak intensity of (ZnCu)Sn(OH)6 is significantly greater than that of A5Sn(OH)6. This indicates that A5Sn(OH)6 consumes active hydrogen (*H) at a faster rate and adsorbs nitrate ions more strongly.
Claims
1. A high-entropy perovskite hydroxide, characterized in that, The high-entropy perovskite hydroxide is ASn(OH)6, wherein A is one or more of Zn, Mn, Co, Ni and Cu.
2. The high-entropy perovskite hydroxide according to claim 1, characterized in that, The high-entropy perovskite hydroxides are (ZnMnCoNiCu)Sn(OH)6, (ZnMn)Sn(OH)6, (ZnCo)Sn(OH)6, (ZnNi)Sn(OH)6, (ZnCu)Sn(OH)6, and ZnSn(OH)6.
3. The method for preparing a high-entropy perovskite hydroxide according to claim 1 or 2, characterized in that, Includes the following steps: 1) Dissolve divalent metal chloride and sodium citrate in water, and dissolve tetravalent tin chloride in ethanol. Mix the two solutions together and stir. 2) Under heating conditions, sodium hydroxide solution was quickly added. After 1 hour, the precipitate was collected by centrifugation, washed several times, and dried to obtain the target product.
4. The method for preparing a high-entropy perovskite hydroxide according to claim 3, characterized in that, In step 1), the divalent metal chloride salt is one or more of manganese chloride, cobalt chloride, nickel chloride, copper chloride, and zinc chloride.
5. The method for preparing a high-entropy perovskite hydroxide according to claim 4, characterized in that, In step 1), the total number of moles of divalent metal chlorides: the number of moles of sodium citrate: the number of moles of tetravalent tin chloride = 1:1:
1. When there are multiple divalent metal chlorides, each divalent metal chloride is added in an equal molar ratio.
6. The method for preparing a high-entropy perovskite hydroxide according to claim 3, characterized in that, In step 2), the heating is carried out at 80°C.
7. The method for preparing a high-entropy perovskite hydroxide according to claim 3, characterized in that, In step 2), the concentration of the sodium hydroxide solution is 2 M.
8. The application of the high-entropy perovskite hydroxide as described in claim 1 or 2 as an electrocatalyst in the electrocatalytic reduction of nitrate.
9. The application according to claim 8, characterized in that, The method is as follows: High-entropy perovskite hydroxide is loaded onto carbon cloth as the working electrode, Ag / AgCl is the reference electrode, platinum sheet is the counter electrode, and a mixed solution of 1.0 M KOH and 0.1 M KNO3 is used for electrocatalytic reduction of nitrate.