Three-dimensional self-supporting copper-cobalt-based catalytic electrode and application of three-dimensional self-supporting copper-cobalt-based catalytic electrode in electrochemical nitrogen reduction synthesis of ammonia
By growing copper hydroxide nanowires on copper foam and electrodepositing cobalt hydroxide, a three-dimensional self-supporting copper-cobalt-based catalytic electrode with a porous nanowire/flower-like structure is formed, which solves the problems of expensive noble metal catalysts and poor stability of powdered catalysts, and achieves the effect of efficient electrochemical nitrogen reduction to synthesize ammonia.
Patent Information
- Application Number
- CN202510918279.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-03
- Publication Date
- 2025-11-25
AI Technical Summary
Existing precious metal catalysts are expensive, which limits the large-scale application of electrochemical nitrogen reduction to ammonia synthesis. Furthermore, common powder catalysts have limited loading capacity, and organic binders have poor conductivity, which affects electrode stability.
A three-dimensional self-supporting copper-cobalt-based catalytic electrode was prepared by growing copper hydroxide nanowires in situ on copper foam and electrodepositing cobalt hydroxide to form a nanoflower structure, followed by annealing to prepare a porous nanowire/flower structure to increase active sites.
It improves the efficiency of electrochemical nitrogen reduction for ammonia synthesis, enhances electrode stability and catalytic performance, and reduces preparation costs.
Smart Images
Figure CN121006571A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of materials preparation technology, and in particular to a three-dimensional self-supporting copper-cobalt-based catalytic electrode and its application in electrochemical nitrogen reduction synthesis of ammonia. Background Technology
[0002] Ammonia is an essential chemical product for social development. The emerging electrochemical nitrogen reduction synthesis of ammonia is characterized by its cleanliness and renewability. Using abundant nitrogen and water as raw materials, it reacts under mild conditions to produce ammonia while achieving zero carbon emissions. However, the breaking of the nitrogen-nitrogen triple bond requires very high energy, and the ammonia production process involves a six-electron transfer, while the hydrogen evolution reaction only involves a two-electron transfer and does not require additional bond breaking. Furthermore, the hydrogen evolution reaction has a more easily achievable reduction potential. Therefore, finding a catalyst that can efficiently and continuously drive nitrogen reduction to ammonia at low potentials is crucial for achieving an economical ammonia production process. Currently, noble metal catalysts, represented by gold, are considered the best nitrogen reduction catalysts. However, the rarity and high price of noble metals greatly hinder their large-scale application in electrochemical nitrogen reduction synthesis of ammonia. Therefore, developing inexpensive non-noble metal catalysts to replace current noble metal catalysts has become an important task at this stage. Electrochemical nitrogen reduction ammonia production technology is particularly important for reducing carbon emissions during the ammonia synthesis process.
[0003] In recent years, the synergistic effects of binary or multi-metal compounds have attracted the attention of researchers, especially metals such as copper, cobalt, molybdenum, iron, chromium, and nickel, and their compounds. Among them, copper has been shown to inhibit the hydrogen evolution reaction, and it is inexpensive and has good electrical conductivity. Therefore, various forms of copper-based catalysts have been developed for research on electrocatalytic ammonia synthesis.
[0004] Currently, most electrocatalysts are in powder form, requiring organic binders to fix them onto the working electrode. Limited catalyst loading, poor conductivity of the organic binder, and catalyst detachment all affect electrode stability. In contrast, three-dimensional self-supporting electrodes not only have a larger active surface area, which is beneficial for electron transport and proton transfer, but also exhibit high efficiency, simple fabrication process, and promising application prospects. Therefore, developing a three-dimensional self-supporting copper-based catalyst electrode with high surface area is of great significance. Summary of the Invention
[0005] To address the aforementioned technical challenges, this invention provides a method for preparing a three-dimensional self-supporting copper-cobalt-based catalytic electrode, comprising: placing copper foam in an alkaline solution for in-situ electrochemical oxidation to obtain a copper foam material with copper hydroxide nanowires grown on its surface; then placing the copper foam material with copper hydroxide nanowires grown on its surface in a cobalt source solution for electrodeposition of cobalt hydroxide to obtain an electrode with nanoflowers grown on its surface; and finally annealing the electrode with nanoflowers grown on its surface to obtain the three-dimensional self-supporting copper-cobalt-based catalytic electrode.
[0006] Preferably, the length of the copper hydroxide nanowire is 300~500 nm.
[0007] Preferably, the diameter of the nanoflower is 450~550 nm, more preferably 480~520 nm.
[0008] Preferably, the alkaline solution is a KOH solution; and / or, the cobalt source solution is a cobalt nitrate solution.
[0009] Preferably, the in-situ electrochemical oxidation is a constant potential oxidation at a potential of -1.5 to -0.5 V.
[0010] Preferably, the in-situ electrochemical oxidation time is 950~1050 s.
[0011] Preferably, the electrodeposited cobalt hydroxide is electrodeposited at a potential of -1.5 to -0.5 V.
[0012] Preferably, the annealing conditions include: heating to 350-450°C at a rate of 3-10°C / min in an atmospheric environment, holding at that temperature for 0.5-2 hours, and then cooling.
[0013] Furthermore, the present invention provides a three-dimensional self-supporting copper-cobalt-based catalytic electrode prepared by the above preparation method.
[0014] Furthermore, the present invention provides the application of the three-dimensional self-supporting copper-cobalt-based catalytic electrode in the electrochemical nitrogen reduction synthesis of ammonia.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a three-dimensional self-supporting copper-cobalt based electrode. The invention modifies the surface of copper foam by uniformly covering its surface with copper hydroxide nanowires, and further electrochemically deposits cobalt hydroxide. The large surface area provided by the copper hydroxide nanowires increases the number of active sites. Subsequently, the corresponding cobalt-copper oxide is prepared by annealing, so that the flat structure is transformed into a porous three-dimensional structure with nanowires / flowers, which increases the exposure of active sites and promotes the nitrogen reduction to ammonia production performance. Attached Figure Description
[0016] Figure 1This is the electrochemical process curve of the three-dimensional self-supporting copper-cobalt-based catalytic electrode in Example 1.
[0017] Figure 2 These are SEM images of Cu(OH)2 / CF after Cu(OH)2 nanowires were grown in Example 1; where (a) is a 100-micrometer scale SEM image, (b) is a 20-micrometer scale SEM image, (c) is a 10-micrometer scale SEM image, and (d) is a 1-micrometer scale SEM image.
[0018] Figure 3 This is a SEM image of the three-dimensional self-supporting copper-cobalt-based catalytic electrode prepared in Example 1.
[0019] Figure 4 This is the XRD pattern of the three-dimensional self-supporting copper-cobalt-based catalytic electrode of Example 1.
[0020] Figure 5 This is a graph showing the electrochemical nitrogen reduction to ammonia synthesis curve of the three-dimensional self-supporting copper-cobalt-based catalytic electrode in Example 1.
[0021] Figure 6 This is a comparative three-dimensional self-supporting copper-nickel-based catalytic electrode electrochemical nitrogen reduction to ammonia synthesis curve. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. In the embodiments provided in this specification, where specific techniques or conditions are not specified, they are performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.
[0023] Example 1 This embodiment provides a three-dimensional self-supporting copper-cobalt-based catalytic electrode, the preparation method of which is as follows: (1) Cut the copper foam (CF) into 1 x 2 cm pieces. 2 The flakes were placed in 3 mol / L hydrochloric acid and ethanol respectively for ultrasonic cleaning for 5 min, then rinsed with deionized water and dried in an oven. (2) Using copper foam (CF) as the working electrode, graphite plate as the counter electrode, and saturated Ag / AgCl electrode as the reference electrode, in-situ electrochemical oxidation was carried out in 40 mL of 1 mol / L KOH solution to modify its surface. Constant potential oxidation was performed at -1 V for 1000 s to grow copper hydroxide nanowires on the surface, thus obtaining copper foam material (Cu(OH)2 / CF) with copper hydroxide nanowires grown on the surface. The length of the nanowires was 300~500 nm. (3) Prepare 40 mL of 0.1 mol / L cobalt nitrate solution, and use the Cu(OH)2 / CF obtained in (2) as the working electrode to electrodeposit cobalt hydroxide in the cobalt nitrate solution at a potential of -1 V to obtain an electrode (Co(OH)2 / Cu(OH)2 / CF) with nanoflowers growing on the surface; the nanoflower size is about 500 nm. (4) Anneal the Co(OH)2 / Cu(OH)2 / CF in a muffle furnace under atmospheric conditions at a heating rate of 5. o C / min, heating to 400 o After being kept at C for 2 h, and then naturally cooled, Co3O4 / CuO was obtained, which is a three-dimensional self-supporting copper-cobalt based catalytic electrode.
[0024] Example 2 This embodiment provides a three-dimensional self-supporting copper-cobalt-based catalytic electrode, the only difference in its preparation method from that of Example 1 is that the constant potential oxidation time is 800 s.
[0025] Example 3 This embodiment provides a three-dimensional self-supporting copper-cobalt-based catalytic electrode, the only difference in its preparation method from that of Example 1 is that the constant potential oxidation time is 1200 s.
[0026] Comparative Example This comparative example provides an electrode whose preparation method differs from that of Example 1 only in that cobalt nitrate solution is replaced with nickel nitrate solution to obtain a three-dimensional self-supporting copper-nickel-based catalytic electrode.
[0027] Experimental Example 1 This experimental example monitors the electrochemical process curves during the electrode preparation process in Example 1 above. The LSV curve of Cu(OH)2 nanowires grown on the CF surface is shown below. Figure 1 As shown, the LSV curve is generally linear within 1000 s. When the reaction time is less than 1000 s, the Cu(OH)₂ nanowires grown on the surface are unevenly distributed; when the time is greater than 1000 s, the Cu(OH)₂ nanowires are over-oxidized. The SEM images of Cu(OH)₂ / CF after Cu(OH)₂ nanowire growth are shown below. Figure 2 As shown.
[0028] SEM image of the three-dimensional self-supporting copper-cobalt-based catalytic electrode prepared in Example 1 is shown below. Figure 3 As shown. When the annealing time is less than 1 hour, the Cu(OH)₂ nanowires have not yet formed into a block; when the annealing time is greater than 1 hour, the Cu(OH)₂ nanowires begin to form into a block. Figure 3 The CF framework of the sample in Example 1 can be clearly seen, in which the Cu(OH)2 nanowires exist in the form of CuO blocks after annealing, and are covered with Co3O4 nanoflowers on their surface.
[0029] The XRD pattern of the three-dimensional self-supporting copper-cobalt-based catalytic electrode prepared in Example 1 is shown below. Figure 4 As shown, by Figure 4 It can be seen that the prepared electrode has good crystallinity and no impurity phases appear. It can also be seen that its characteristic peaks are mainly composed of Co3O4 (PDF#42-1467) and CuO (PDF#45-0937).
[0030] Experimental Example 2 This experimental example applies the electrodes prepared in the above examples and comparative examples to the electrochemical nitrogen reduction to ammonia synthesis reaction, comparing the catalytic performance of different electrodes. The steps are as follows: LSV tests were performed on the electrode materials of different embodiments and comparative examples in 0.1 mol / L sodium sulfate solutions filled with saturated N2 and 0.1 mol / L sodium sulfate solutions filled with saturated Ar, respectively.
[0031] Test results are as follows Figure 5 As shown, compared with the Ar environment, the electrode material of Example 1 exhibits a significantly increased LSV current density under N2 conditions, indicating its higher catalytic efficiency for NRR. Furthermore, the LSV test results of the comparative electrode materials are shown below. Figure 6 As shown, the catalytic performance of the electrode material in Example 1 is significantly better than that of the comparative example.
[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a three-dimensional self-supporting copper-cobalt-based catalytic electrode, characterized in that, include: Copper foam was subjected to in-situ electrochemical oxidation in an alkaline solution to obtain a copper foam material with copper hydroxide nanowires grown on its surface. Then, the copper foam material with copper hydroxide nanowires grown on its surface was placed in a cobalt source solution to electrodeposit cobalt hydroxide to obtain an electrode with nanoflowers grown on its surface. Finally, the electrode with nanoflowers grown on its surface was annealed to obtain the three-dimensional self-supporting copper-cobalt-based catalytic electrode.
2. The preparation method according to claim 1, characterized in that, The copper hydroxide nanowires have a length of 300~500 nm.
3. The preparation method according to claim 1, characterized in that, The diameter of the nanoflower is 450~550 nm.
4. The preparation method according to claim 1, characterized in that, The alkaline solution is a KOH solution; and / or, the cobalt source solution is a cobalt nitrate solution.
5. The preparation method according to claim 1, characterized in that, The in-situ electrochemical oxidation is a constant potential oxidation at a potential of -1.5 to -0.5V.
6. The preparation method according to claim 5, characterized in that, The in-situ electrochemical oxidation time is 950~1050 s.
7. The preparation method according to claim 1, characterized in that, The electrodeposited cobalt hydroxide is deposited at a potential of -1.5 to -0.5V.
8. The preparation method according to claim 1, characterized in that, The annealing conditions include: heating to 350-450°C at a rate of 3-10°C / min in an atmospheric environment, holding at that temperature for 0.5-2 hours, and then cooling.
9. The three-dimensional self-supporting copper-cobalt-based catalytic electrode prepared by any one of claims 1 to 8.
10. The application of the three-dimensional self-supporting copper-cobalt-based catalytic electrode of claim 9 in the electrochemical nitrogen reduction synthesis of ammonia.