Cu2O coated Cu1. 94S egg shell nano-structure catalyst as well as preparation method and application of Cu2O coated Cu1. 94S egg shell nano-structure catalyst
By forming a Cu1.94S shell on Cu2O nanocrystals, the problems of low catalytic activity and poor selectivity of Cu2O were solved, and the efficient and stable reduction of nitrate to ammonia was achieved.
Patent Information
- Application Number
- CN202511037964.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-10-31
AI Technical Summary
Cu2O catalysts suffer from low current density, low catalytic activity, and poor selectivity in the electrocatalytic reduction of nitrates to ammonia, and are unstable during long-term use.
Using Cu2O nanocrystals as templates, anion exchange was performed with sulfur ions, and monovalent copper ions and sodium sulfide were combined to form a Cu1.94S shell, thus preparing a Cu2O@Cu1.94S eggshell nanostructure catalyst.
The catalyst exhibits improved current density and catalytic selectivity, higher catalytic activity and stability, significantly enhanced NO3- conversion efficiency, and maintained structural stability at room temperature for at least 2 months.
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Figure CN120866868A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of functional materials technology, and particularly to a Cu2O@Cu 1.94 S-shell nanostructure catalysts, their preparation methods, and applications. Background Technology
[0002] With the accelerating pace of industrialization and agricultural intensification, nitrate pollution has become a global environmental challenge. Its main sources are industrial wastewater from metallurgy, electroplating, and explosives manufacturing, as well as excessive application of agricultural fertilizers, which release large amounts of nitrates into water bodies through surface runoff and groundwater infiltration. This not only leads to eutrophication and imbalances in aquatic ecosystems but also directly threatens human health. Ammonia (NH3), as a precursor to fertilizers, various chemicals, fuels, and energy carriers, has wide-ranging practical applications and is crucial to industrial, agricultural, and human development as a whole. Currently, industrial NH3 production mainly relies on the traditional Haber-Bosch process, which requires relatively harsh reaction conditions and consumes 1-2% of global energy supply and emits over 400 million tons of CO2 annually. Given the current global climate governance framework's requirement for net-zero emissions, there is an urgent need to develop a synthetic ammonia technology that combines mild operating conditions with eco-friendly properties.
[0003] Electrocatalytic reduction of ammonia by nitrate (NO3RR) using H2O and NO3 in the electrolyte. - Using hydrogen and nitrogen sources, an external current drives the cathode catalyst to achieve the synthesis of NH3 and NO3 at room temperature. - Pollution removal. This technology has attracted widespread attention due to its unique advantages. Therefore, electrocatalytic reduction of ammonia from nitrate under mild conditions has become a green ammonia synthesis technology that can both treat nitrate pollution and replace traditional processes, and is currently a key area of interdisciplinary research in environmental catalysis and energy science. Copper-based catalysts, due to their unique d-orbital electronic state density regulation mechanism, have shown significant performance advantages in electrocatalytic reduction of ammonia from nitrate (NO3RR), and have become one of the mainstream catalyst systems in the current NO3RR field. Among them, Cu2O, as a common semiconductor material, can catalyze NO3 reduction. - Electroreduction produces ammonia (NH3). However, Cu2O undergoes NO3-reduction. - Reduction catalysis faces several challenges: Cu2O has a low current density, limiting its catalytic activity and reducing catalytic efficiency; furthermore, Cu2O has a negative effect on NO3- during the electrocatalytic reduction of nitrate to ammonia. - The selectivity is low, and byproducts will appear. In long-term testing, Cu2O also shows catalyst instability. Summary of the Invention
[0004] Therefore, the purpose of this invention is to provide a Cu2O@Cu 1.94 S-shell nanostructured catalyst, its preparation method and application: Using Cu2O nanocrystals as templates, it undergoes anion exchange with sulfide ions, and monovalent copper ions combine with sodium sulfide added to the reaction system, nucleating and forming Cu on the Cu2O nanocrystals. 1.94 S-shell, the prepared Cu2O@Cu 1.94 S-shell nanostructure catalysts have high current density, high catalytic selectivity and activity, higher catalytic efficiency, and can maintain structural and performance stability even after long-term storage.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention first provides a Cu2O@Cu 1.94 The preparation method of the S-shell nanostructure catalyst includes the following steps: dispersing sodium sulfide in deionized water to obtain a sodium sulfide solution; adding Cu2O nanocrystals to methanol, reacting in an ice bath, adding sodium sulfide solution, continuing the reaction, and post-processing to obtain Cu2O@Cu 1.94 S-shell nanostructure catalyst.
[0006] As a further improvement to the above-mentioned scheme of the present invention, the ice bath reaction is controlled to react the reaction solution at 0-10℃ for 0.1-10 min, and the continued reaction is reacted at 0-10℃ for 0.1-10 min.
[0007] As a further improvement to the above-described scheme of the present invention, the molar volume ratio of sodium sulfide, Cu₂O nanocrystals, and methanol is 0.05-0.2 mmol: 0.25-0.75 mmol: 3-10 mL. Preferably, the molar volume ratio of sodium sulfide, Cu₂O nanocrystals, and methanol is 0.1-0.15 mmol: 0.25-0.75 mmol: 4-6 mL.
[0008] As a further improvement to the above-mentioned solution of the present invention, the post-processing includes several centrifugal washing and drying cycles, wherein the centrifugal washing is performed using ethanol.
[0009] As a further improvement to the above-mentioned scheme of the present invention, the preparation method of Cu2O nanocrystals is as follows: copper acetate and dispersion medium are mixed, heated to react, and then post-treated to obtain Cu2O nanocrystals.
[0010] As a further improvement to the above-described scheme of the present invention, the heating reaction is carried out at 160-200°C for 15-40 minutes. The preferred heating reaction temperature is 180-190°C.
[0011] As a further improvement to the above-mentioned scheme of the present invention, the molar volume ratio of copper acetate to the dispersion medium is 0.5-1.5 mmol: 2-7 mL.
[0012] As a further improvement to the above-described scheme of the present invention, the dispersion medium is at least one of octadecene and oleylamine; preferably, in order to improve the dissolution effect of copper acetate, the dispersion medium is octadecene and oleylamine. The post-treatment includes centrifugal washing and drying in sequence, wherein the centrifugal washing is performed sequentially with n-hexane and ethanol.
[0013] The present invention also provides a Cu2O@Cu 1.94 The S-shell nanostructure catalyst was prepared using the preparation method described above.
[0014] The present invention also provides a Cu2O@Cu prepared by the preparation method described above. 1.94 Application of S-shell nanostructure catalysts in electrocatalytic reduction of nitrates to ammonia, or in the removal of nitrates from wastewater.
[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention uses Cu₂O nanocrystals as a template, undergoes anion exchange with sulfur ions, and combines monovalent copper ions with sodium sulfide added to the reaction system, thereby nucleating and forming Cu on the Cu₂O nanocrystals. 1.94 The S-shell layer was used to finally prepare Cu2O@Cu. 1.94 The S-shell nanostructure catalyst has a simple preparation method and high controllability. The prepared Cu2O@Cu 1.94 S-shell nanostructure catalysts exhibit high current density, stable structure, and stable product performance.
[0016] Compared to the catalytic efficiency of Cu2O, the Cu2O@Cu prepared in this invention has a higher catalytic efficiency. 1.94 S-shell nanostructure catalysts exhibit higher current density, higher catalytic selectivity and activity, and higher catalytic efficiency, significantly improving the electrocatalytic NO3-reduction reaction of single-component Cu2O. - The conversion efficiency has been improved, solving the problem in existing technologies where Cu2O is affected by NO3. - The low product selectivity and low current density during reduction limit its catalytic activity and application in catalytic processes, but it has broad market application prospects. Furthermore, this invention, Cu2O@Cu... 1.94 The S-shell nanostructure catalyst remains colloidally stable in air and at room temperature for at least two months without any changes in structure, composition, or electrochemical performance; the formed yolk structure has a larger specific surface area and more active sites, enabling it to adsorb more NO3. -It significantly improves the activity, selectivity and stability of NO3RR, and has great catalytic potential.
[0017] The Cu2O@Cu of the present invention 1.94 S-shell nanostructure catalysts exhibit excellent nitrate reduction catalytic activity, high catalytic Faraday efficiency, and high yield. They show significant effects on the activity, selectivity, and stability of electrocatalytic NO3RR, demonstrating great catalytic potential to solve nitrate pollution and reduce meaningful ammonia. Attached Figure Description
[0018] Figure 1 TEM image of Cu2O nanocrystals prepared in Example 1; Figure 2 Cu2O@Cu prepared in Example 1 1.94 TEM image of the S-shell nanostructure catalyst; Figure 3 Cu2O nanocrystals and Cu2O@Cu prepared in Example 1 1.94 XRD pattern of S-shell nanostructure catalyst; Figure 4 Cu2O@Cu 1.94 Faraday efficiency diagram of potassium nitrate to ammonia reduction of S eggshell nanostructure catalyst and Cu2O nanocrystals under different voltages. Figure 5 Cu2O@Cu 1.94 The yield diagram of potassium nitrate reduction to ammonia by S eggshell nanostructure catalyst and Cu2O nanocrystals under different voltages. Figure 6 Cu2O@Cu 1.94 S eggshell nanostructure catalyst and Cu2O nanocrystal electrocatalytic reduction of potassium nitrate to ammonia isotope labeling diagram; Figure 7 Cu2O@Cu 1.94 Current density diagrams of S eggshell nanostructure catalyst and Cu2O nanocrystals at different potentials. Figure 8 Cu2O@Cu prepared in Example 1 1.94 TEM image of the S-shell nanostructure catalyst after being kept in air at room temperature for 2 months; Figure 9 Cu2O@Cu prepared in Example 1 1.94 Faraday efficiency diagram of potassium nitrate to ammonia gas reduction at different voltages after the S-shell nanostructure catalyst was kept in air at room temperature for 2 months; Figure 10 Cu2O@Cu prepared in Example 1 1.94The yield of potassium nitrate to ammonia reduced by different voltages after the S-shell nanostructure catalyst was kept in air at room temperature for 2 months. Detailed Implementation
[0019] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.
[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
[0021] Example 1 This embodiment proposes a Cu2O@Cu 1.94 The preparation method of the S-shell nanostructure catalyst includes the following steps: (1) Preparation of Cu2O nanocrystals S11. Add 1 mmol Cu(CH3COO)2 to a three-necked flask, add 5 mL octadecene and 2 mL oleylamine to dissolve Cu(CH3COO)2, heat to 180℃ and react for 30 min. The solution quickly changes from blue to yellow. S12. Cool the solution from step S11 to room temperature, and wash the product with hexane and ethanol successively to obtain the reaction product; S13. Dry the reactants from S12 to obtain Cu2O nanocrystals; 2. Preparation of Cu2O@Cu 1.94 S-shell nanostructure catalyst S21. Add 0.5 mmol Cu2O nanocrystals and 5 mL methanol to a three-necked flask, maintain the solution temperature at 5 °C in an ice bath, and react for 5 minutes. S22. Dissolve 0.1 mmol of sodium sulfide in 2 mL of deionized water by sonication to obtain a sodium sulfide solution. Add the sodium sulfide solution to the three-necked flask in S21 and continue stirring for 1 min. S23. The product was washed and centrifuged multiple times with ethanol, then dried to obtain Cu2O@Cu. 1.94 S-shell nanostructure catalyst.
[0022] The Cu₂O nanocrystals prepared in this embodiment were characterized by TEM, and the characterization results are shown in the figure. Figure 1 .from Figure 1It is clear that the Cu2O nanocrystal structure is a rhombic dodecahedron.
[0023] The Cu2O@Cu prepared in this embodiment 1.94 The S-shell nanostructure catalyst was characterized by TEM. The characterization results are shown in the figure. Figure 2 .from Figure 2 It can be seen that the rhombic dodecahedral Cu₂O core is surrounded by a layer of rhombic dodecahedral Cu. 1.94 S-shell.
[0024] The Cu2O nanocrystals and Cu2O@Cu prepared in this embodiment 1.94 The S-shell nanostructured catalysts were characterized by XRD, and the standard results are as follows: Figure 3 ,Depend on Figure 3 As can be seen, the black peaks in the upper spectrum represent Cu2O@Cu. 1.94 S-shell nanostructures, whose peaks can interact with Cu2O and Cu 1.94 The standard card for S corresponds correctly. The gray spectrum below shows the peaks of the Cu2O rhombic dodecahedron, which correspond to the standard card for Cu2O. This proves that the Cu2O@Cu spectrum in this embodiment... 1.94 Successful preparation of S-eggshell nanostructure catalyst.
[0025] Example 2 The difference between this embodiment and Embodiment 1 is that in step S11 of this embodiment, the amount of oleylamine used is 1 mL.
[0026] Example 3 The difference between this embodiment and Embodiment 1 is that in step S11 of this embodiment, the amount of oleylamine used is 3 mL.
[0027] Example 4 The difference between this embodiment and Embodiment 1 is that in step S11 of this embodiment, the amount of oleylamine used is 4 mL.
[0028] Example 5 The difference between this embodiment and embodiment 1 is that the reaction temperature in step S11 of this embodiment is 160°C.
[0029] Example 6 The difference between this embodiment and Embodiment 1 is that the reaction temperature in step S11 of this embodiment is 170°C.
[0030] Example 7 The difference between this embodiment and Embodiment 1 is that the reaction temperature in step S11 of this embodiment is 190°C.
[0031] Example 8 The difference between this embodiment and embodiment 1 is that the reaction time in step S11 of this embodiment is 20 minutes.
[0032] Example 9 The difference between this embodiment and embodiment 1 is that the reaction time in step S11 of this embodiment is 25 minutes.
[0033] Example 10 The difference between this embodiment and embodiment 1 is that the reaction time in step S11 of this embodiment is 35 minutes.
[0034] Example 11 The difference between this embodiment and embodiment 1 is that the reaction time in step S11 of this embodiment is 40 minutes.
[0035] Example 12 The difference between this embodiment and embodiment 1 is that the reaction time in step S22 of this embodiment is 0.5 min.
[0036] Test Example 1 The Cu2O@Cu prepared in Example 1 1.94 The catalytic efficiency of the S eggshell nanostructure catalyst and the existing Cu2O nanocrystals (the Cu2O nanocrystals prepared in Example 1 were used directly in this test example) was tested.
[0037] The specific method is as follows: Weigh out equal stoichiometric amounts of Cu₂O nanocrystals and Cu₂O@Cu. 1.94 S-shell nanostructured catalysts were dissolved in a certain amount of isopropanol, and a small amount of Nafion solution was added as a binder. The mixture was ultrasonicated for half an hour to ensure uniform dispersion, and then dropped onto 1cm × 1cm carbon paper. Using 0.1M KOH and 0.1M KNO3 as electrolytes, the two catalysts were tested and analyzed in an H-type electrolytic cell system. The liquid products were detected using a UV spectrophotometer. The results are shown below. Figure 4 , Figure 5 .
[0038] Figure 4 The main NO3 content is shown at different potentials and under a reversible hydrogen electrode (RHE). - Distribution of reduction products. Among them, Cu₂O@Cu prepared in Example 1... 1.94 The S-shell nanostructure catalyst, at a voltage of -0.8V, NO3 - Faraday efficiency is as high as 88.69%.
[0039] Figure 5 The yields of reduction product NH3 at different potentials and under reversible hydrogen electrode (RHE) are shown in Example 1 for Cu2O@Cu. 1.94The S-shell nanostructure catalyst exhibits a high NH3 yield of 14.99 mgh at a voltage of -1.0 V. -1 cm -2 It can be seen that Cu2O@Cu 1.94 S-shell nanostructure catalyst in nitrate reduction of NO3 - The Faraday efficiency is significantly higher than that of pure Cu₂O, indicating that the Cu₂O@Cu prepared in this invention... 1.94 The S-shell nanostructure catalyst performed best in nitrate reduction tests, exhibiting excellent selectivity and higher catalytic efficiency. Figure 6 The isotopic labeling shows that the ammonia produced comes from nitrates, not from nitrogen or other sources in the air.
[0040] Figure 7 Cu2O@Cu was displayed 1.94 The current densities of the S-shell nanostructure catalyst and Cu2O nanocrystals at different potentials show that the Cu2O@Cu of this application... 1.94 S-shell nanostructure catalysts exhibit better current density and better conductivity.
[0041] Test Example 2: Cu2O@Cu 1.94 Stability testing of S-shell nanostructure catalyst The Cu2O@Cu prepared in Example 1 1.94 The S-shell nanostructure catalyst was left in air at room temperature for 2 months. Figure 8 Cu2O@Cu prepared in Example 1 1.94 TEM images of the S-shell nanostructured catalyst after being kept in air at room temperature for 2 months. Figure 8 It can be seen that even Cu2O@Cu 1.94 The S-shell nanostructure catalyst did not undergo significant morphological changes after being stored for a long period of time, indicating that the catalyst has good structural stability.
[0042] Following the method described in Test Example 1 above, Cu2O@Cu was kept in air at room temperature for 2 months. 1.94 The catalytic efficiency of the S-shell nanostructure catalyst was tested, and the results are as follows: Figure 9 , Figure 10 As shown.
[0043] from Figure 9 It can be seen that after being kept in air at room temperature for 2 months, the Cu2O@Cu prepared in Example 1 showed... 1.94 The S-shell nanostructure catalyst, at a voltage of -0.8V, NO3 - Faraday efficiency can still be maintained at around 88%.
[0044] from Figure 10 It can be seen that after being kept in air at room temperature for 2 months, the Cu2O@Cu prepared in Example 1 showed... 1.94 The S-shell nanostructure catalyst still achieved an NH3 yield of 18.67 mgh at a voltage of -1.0 V. -1 cm -2 This demonstrates that the Cu2O@Cu of this application... 1.94 The S-shell nanostructure catalyst remains colloidally stable in air and at room temperature for at least 2 months without any changes in structure, composition, or electrochemical properties.
[0045] In summary, the embodiments of the present invention utilize anion exchange and seed growth methods, using Cu₂O rhombic dodecahedrons as templates, to perform anion exchange with sulfide ions, while monovalent copper ions combine with sodium sulfide added to the reaction system, thereby forming Cu on the Cu₂O rhombic dodecahedrons. 1.94 The S-shell layer was used to finally prepare Cu2O@Cu. 1.94 S-shell nanostructure catalyst, which, compared to Cu2O, produces NO3 - The selectivity of the reduced product is greatly improved, and it remains colloidally stable in air and at room temperature for at least 2 months without any changes in structure, composition or electrochemical properties.
[0046] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0047] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A Cu2O@Cu 1.94 The method for preparing S-egg-shell nanostructure catalyst is characterized by, The process includes the following steps: dispersing sodium sulfide in deionized water to obtain a sodium sulfide solution; adding Cu₂O nanocrystals to methanol, reacting in an ice bath, adding the sodium sulfide solution, continuing the reaction, and then post-processing to obtain Cu₂O@Cu 1.94 S-shell nanostructure catalyst.
2. The Cu2O@Cu according to claim 1 1.94 The method for preparing S-egg-shell nanostructure catalyst is characterized by, The ice bath reaction is controlled by reacting the reaction solution at 0-10℃ for 0.1-10 min, and the continued reaction is carried out at 0-10℃ for 0.1-10 min.
3. The Cu2O@Cu according to claim 1 1.94 The method for preparing S-egg-shell nanostructure catalyst is characterized by, The molar volume ratio of the sodium sulfide, the Cu2O nanocrystals, and the methanol is 0.05-0.2 mmol: 0.25-0.75 mmol: 3-10 mL.
4. The Cu2O@Cu according to claim 1 1.94 The method for preparing S-egg-shell nanostructure catalyst is characterized by, The post-processing includes several cycles of centrifugal washing and drying, wherein the centrifugal washing is performed using ethanol.
5. The Cu2O@Cu according to claim 1 1.94 The method for preparing S-egg-shell nanostructure catalyst is characterized by, The preparation method of Cu2O nanocrystals is as follows: copper acetate and dispersion medium are mixed, heated to react, and then post-treated to obtain Cu2O nanocrystals.
6. The Cu2O@Cu according to claim 5 1.94 The method for preparing S-egg-shell nanostructure catalyst is characterized by, The heating reaction is carried out at 160-200℃ for 15-40 minutes.
7. The Cu2O@Cu according to claim 5 1.94 The method for preparing S-egg-shell nanostructure catalyst is characterized by, The molar volume ratio of the copper acetate to the dispersion medium is 0.5-1.5 mmol: 2-7 mL.
8. The Cu2O@Cu according to claim 5 1.94 The method for preparing S-egg-shell nanostructure catalyst is characterized by, The dispersion medium is at least one of octadecene and oleylamine; the post-treatment includes centrifugal washing and drying, wherein the centrifugal washing is performed sequentially with n-hexane and ethanol.
9. A Cu2O@Cu 1.94 S-shell nanostructure catalyst, characterized in that... It is prepared by the preparation method described in any one of claims 1-8.
10. A Cu₂O@Cu prepared by the method described in any one of claims 1-8 1.94 Application of S-shell nanostructure catalysts in electrocatalytic reduction of nitrates to ammonia, or in the removal of nitrates from wastewater.