Cu (OH) 2 nanotube array with Cu2O polyhedral particles loaded on surface and preparation method and application of Cu (OH) 2 nanotube array
By preparing Cu(OH)2 nanotube arrays with Cu2O polyhedral particles loaded on the surface, the problems of low selectivity and high energy consumption of existing electrocatalytic materials were solved, achieving efficient conversion of nitrate to nitrogen gas, reducing the concentration of nitrate in water and reducing toxic intermediate products.
Patent Information
- Application Number
- CN202511050957.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2025-11-25
AI Technical Summary
Existing electrocatalytic materials have low selectivity in reducing nitrates, high energy consumption, and the presence of harmful NO2- intermediates, making it difficult to efficiently convert them into non-toxic nitrogen gas, resulting in poor nitrogen reduction and removal effects in water bodies.
Cu(OH)2 nanotube arrays with Cu2O polyhedral particles loaded on the surface were prepared on copper foam by anodic oxidation and wet chemical methods. Subsequently, crystal face modifiers and weak reducing agents were added to an alkaline solution to grow Cu2O polyhedral particles in situ, forming a composite structure catalytic electrode.
It improves the nitrate reduction rate and NO2- catalytic reduction activity, significantly reduces NO2- concentration, achieves efficient and selective conversion to nitrogen gas, reduces nitrate nitrogen concentration in water, and avoids secondary pollution.
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Figure CN121006573A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of electrocatalytic electrode materials, and particularly relates to a Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface, a preparation method and application thereof in electrocatalytic reduction of nitrate to nitrogen. BACKGROUND
[0002] Excessive nitrate content in water bodies not only brings a series of water eutrophication and other malignant ecological environment problems to the environment, but also seriously endangers human health. At present, the methods for removing nitrate in water mainly include microbial technology, ion exchange technology, adsorption technology, reverse osmosis technology, electrodialysis technology, photocatalytic reduction technology, chemical catalytic reduction technology, electrocatalytic reduction technology and photoelectrochemical reduction technology, and many beneficial results have been achieved. Among them, the electrocatalytic technology reduces nitrate to nitrogen gas to escape from water, thereby reducing the total nitrogen concentration in water, and has application potential for water denitrification and nitrogen removal. At present, this method also has corresponding problems, such as the low selectivity of existing catalytic materials for nitrogen (most catalytic materials reduce nitrate to ammonia / ammonium, which cannot be applied to water denitrification and nitrogen removal). In addition, the need for high reaction potential means high energy consumption. For example, when Sn is used as a cathode material, the reduction rate of nitrate is high (0.206 mmol min -1 cm -2 ) at a voltage of-2.9 V (vs. Ag / AgCl), and the selectivity of nitrogen is also high (92%). However, such a high negative bias also leads to intense side reactions such as hydrogen evolution, and the Faraday efficiency of nitrate reduction is low, i.e., there are problems such as high energy consumption and low conversion efficiency.
[0003] In order to solve this problem, more and more metal materials are used as reaction cathodes, such as Mo, Ti, Fe, Co, Ni, Al, Pd and Cu. However, they generally have high selectivity for NH4 + . In addition, NO3 - reduction intermediate (first step reduction reaction) NO2 - has very great harm to the aquatic ecosystem and human health, produces more harmful secondary pollution, and cannot be practically applied. How to reduce the concentration of NO2 - in the catalytic reaction process, or improve the catalytic efficiency of NO2 - conversion to nitrogen, is an important challenge in the design of catalytic materials for electrocatalytic removal of nitrate in water. SUMMARY
[0004] One of the purposes of the present application is to provide a preparation method of a Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface, which constructs a composite structure catalytic electrode of two different Cu-based materials, improves the reduction rate of NO3 - , and improves the selectivity of NO2- The catalytic reduction activity of the Cu2O polyhedral particle surface-loaded Cu(OH)2 nanotube array is high, and the nitrate is converted into non-toxic nitrogen gas with high efficiency and high selectivity, so that the concentration of nitrated nitrogen in water is reduced, and a new material and method for reducing and removing nitrogen in water are provided.
[0005] To achieve the above object, the application adopts the following technical scheme: a preparation method of Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface, comprising the following steps:
[0006] S1, configure 1-3M sodium hydroxide solution as electrolyte, clean the foamed copper as working electrode, platinum net as counter electrode, and mercury amalgam electrode as reference electrode, take out the foamed copper after anodic oxidation, rinse and dry, and prepare copper hydroxide nanowire array on the foamed copper, which is recorded as Cu(OH)2NWs / CF;
[0007] S2, sequentially add sodium hydroxide solution and polyvinylpyrrolidone in deionized water to obtain a mixed solution; heat and keep the mixed solution, add Cu(OH)2NWs / CF prepared in step S1 for sufficient infiltration, then add a weak reducing agent, take out and rinse and dry after 1-3 hours of reaction, and prepare Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface on the foamed copper, which is recorded as Cu2O / Cu(OH)2NTA.
[0008] Further improvement on the preparation method of Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface:
[0009] Preferably, in step S1, the foamed copper is anodized for 1-3h by applying a constant current of 10-30mA through an electrochemical workstation.
[0010] Preferably, in the mixed solution of step S2, the concentration of sodium hydroxide is 0.01-0.1M, and the concentration of polyvinylpyrrolidone is 0.01-0.025g / ml.
[0011] Preferably, in step S2, the mixed solution is heated to 45-65℃ and kept stable.
[0012] Preferably, in step S2, the foamed copper after anodic oxidation is soaked in the mixed solution for 1-3 hours.
[0013] Preferably, in step S2, the weak reducing agent is one of ascorbic acid, glucose solution and polyhydric alcohol, and the concentration of the weak reducing agent added to the solution in the mixed solution is 0.003-0.01M.
[0014] The second object of the present application is to provide a preparation method of the Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles.
[0015] The third object of the present application is to provide an application of the Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles as an electrocatalytic electrode material in treating nitrate contaminated water, in which the contaminated water containing 10-200 ppm of NO3 - is used as an electrolyte, the Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles is used as a working electrode, and Ag / AgCl is used as a reference electrode, and the nitrate is reduced under a negative bias voltage of-1.0 to-1.6 V.
[0016] The application of the Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles as an electrocatalytic electrode material in treating nitrate contaminated water is further improved in that:
[0017] Preferably, the nitrate is reduced under a negative bias voltage of-1.2 V.
[0018] Preferably, the reaction solution is taken as a sample after a period of time, and the contents of NO3 - , NO2 - and NH4 + in the solution are detected by an ion chromatograph.
[0019] The present application has the following advantages over the prior art:
[0020] 1. The present application provides a preparation process of a Cu(OH)2 nanotube array composite structure loaded with cuprous oxide polyhedral particles. The process adopts a wet chemical method. First, a Cu(OH)2 nanowire array with a large specific surface area and active sites is prepared on a foam copper by anodic oxidation. Then, the Cu(OH)2 array is immersed in a mixed solution containing sodium hydroxide and a crystal face modifier polyvinylpyrrolidone. Due to the surface tension of the Cu(OH)2 array, the Cu(OH)2 array is fully infiltrated to fully contact the crystal face modifier on the surface of the Cu(OH)2 array. A weak reducing agent is added. The partial dissolution of the Cu(OH)2 array in the alkaline solution provides a copper source, which is conducive to the in-situ growth of cuprous oxide polyhedral particles on the surface of the Cu(OH)2 nanowire array. The surface layer of the Cu(OH)2 nanowire is continuously dissolved and regenerated in the alkaline solution. Based on the Kirkendall effect, the Cu(OH)2 nanowire gradually becomes a hollow nanotube. Controlling the reaction temperature and selecting a weak reducing agent can ensure that the Cu(OH)2 is not reduced to elemental copper in the reducing aqueous solution, and at the same time, the cuprous oxide polyhedral particles can be grown in-situ on the surface of the Cu(OH)2.
[0021] 2、The present application is based on catalytic theory, and the copper-based material has good hydrogen evolution inhibition effect. The present application selects the high-density cuprous oxide nanotube array / cuprous oxide polyhedral particle composite structure grown on the surface of the foam copper, fully utilizes the high selectivity of cuprous oxide to nitrogen, further uses the cupric hydroxide nanotube as a support material to increase the electrocatalytic active area and improve the catalytic reduction rate of NO2 - , and finally realizes the efficient and high-selective catalytic reduction of nitrate to nitrogen, and the toxic intermediate product NO2 - is significantly reduced. The cupric hydroxide nanotube array prepared in the present application has a large specific surface area, a unique geometric structure and abundant active sites, which lays an important foundation for improving the electrocatalytic efficiency. The copper source for the growth of the cuprous oxide polyhedral particle comes from the dissolution of the cupric hydroxide, that is, the cuprous oxide particles grow in situ on the surface of the cupric hydroxide, so that the two can be closely combined. The unique composite structure realizes the high-efficiency reduction of NO3 - and NO2 - . The cuprous oxide polyhedron grown in situ on the surface of the cupric hydroxide nanotube array is beneficial to improving the selectivity of nitrate reduction to nitrogen. The cupric hydroxide nanotube structure has a large number of active sites, promotes the conversion of the toxic intermediate product NO2 - , prevents the accumulation of NO2 - to produce secondary pollution, and has important significance in the preparation and application of the nitrate water treatment electrode.
[0022] 3、The present application uses polyvinylpyrrolidone to regulate the crystal face of the cuprous oxide nanoparticles, and further improves the selectivity of catalytic reduction of nitrate to nitrogen. Theoretical and experimental results show that the selectivity of the cuprous oxide (111) crystal face to nitrogen is higher, and the selectivity of other materials to ammonia / ammonium is higher. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 The (a) SEM image and (b) TEM image of the cupric hydroxide nanowire array prepared in step S1 of Example 1.
[0024] Figure 2 The X-ray diffraction pattern of the foam copper / cupric hydroxide nanotube array / cuprous oxide polyhedron composite structure electrode prepared in step S2 of Example 1.
[0025] Figure 3 The (a) SEM image and (b) high-magnification TEM image of the cupric hydroxide nanotube array composite structure loaded with cuprous oxide polyhedral particles prepared in step S2 of Example 1.
[0026] Figure 4The test results of nitrate content in water body when Cu2O / Cu(OH)2NTA / CF prepared for Examples 1-4 were used for electrocatalytic reduction of nitrate in sequence; the change trends of NO3 - , NO2 - , NH4 + content and N2 selectivity with time when electrodes prepared by adding different contents of reducing agent were used to remove nitrate in water.
[0027] Figure 5 The contents of NO3 - , NO2 - , NH4 + in solution after Cu2O / Cu(OH)2NTA / CF prepared for Example 5 was used to catalytically reduce nitrate at different voltages (-1.0, -1.2, -1.4, -1.6 V). DETAILED DESCRIPTION
[0028] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with examples, and all other examples obtained by those skilled in the art without creative labor on the basis of the examples in the present application belong to the protection scope of the present application.
[0029] Example 1
[0030] The present embodiment provides a preparation method of Cu(OH)2nanotube array loaded with Cu2O polyhedral particles on surface, and the specific steps are as follows:
[0031] S1, the foamed copper is sequentially cleaned with ethanol, acetone and deionized water, to obtain cleaned foamed copper; a 3M sodium hydroxide solution is prepared, the cleaned foamed copper is used as a working electrode, a platinum mesh is used as a counter electrode, and a mercury-tungsten electrode is used as a reference electrode, a constant current of 20 mA is applied by an electrochemical workstation, the foamed copper is taken out after anodic oxidation for 1 h, washed with deionized water and dried, and a copper hydroxide nanowire array with large specific surface area and active sites is prepared on the foamed copper, which is recorded as Cu(OH)2NWs / CF-1;
[0032] S2, take 20 ml of deionized water, add 0.1 ml of 2M sodium hydroxide solution mixed evenly, and then add 0.3 g of polyvinylpyrrolidone, fully dissolved to obtain a mixed solution; the concentration of sodium hydroxide in the mixed solution is 0.01M, and the concentration of polyvinylpyrrolidone is 0.015 g / ml; the mixed solution is heated to 55°C and kept at a stable temperature, and the Cu(OH)2NWs / CF-1 prepared in step S1 is added, fully infiltrated for 5 min, and then 0.1 ml of 0.6M ascorbic acid solution is added, the concentration of ascorbic acid in the mixed solution is 0.003M, and the reaction is carried out for 1 h, then the foamed copper is taken out, washed and placed at 50°C for 5 h, and Cu2O polyhedral particle loaded Cu(OH)2nanotube array 1 on the foamed copper is prepared, denoted as Cu2O / Cu(OH)2NTA / CF-1.
[0033] Figure 1 The electron microscope image of Cu(OH)2NWs / CF-1 prepared in step S1 can be seen that the surface of the foamed copper is covered with a large number of copper hydroxide nanowires, with a diameter of 200-400 nm and a length of about 10 microns.
[0034] Figure 2 The X-ray diffraction pattern of Cu2O / Cu(OH)2NTA / CF-1 prepared in step S2. From the figure, it can be seen that the prepared copper hydroxide and cuprous oxide match the standard card very well, confirming that the electrode material we prepared is indeed a copper-based electrode material with cuprous oxide and copper hydroxide as one body. Among them, the X-ray diffraction characteristic peak of copper comes from the foamed copper skeleton. Figure 3 (a) and Figure 3 (b) is the SEM and high-magnification TEM images of the prepared Cu2O polyhedral particle loaded Cu(OH)2nanotube array composite structure. It can be seen that the solid copper hydroxide nanowires become hollow nanotubes, and a large number of cuprous oxide polyhedral particles with a size of 200-800 nm are attached to the surface.
[0035] Example 2
[0036] The present embodiment provides a preparation method of Cu(OH)2nanotube array loaded with Cu2O polyhedral particles, and the specific steps refer to Example 1, the difference is only that 0.2 ml of 0.5M ascorbic acid solution is added in step S2, and the concentration of ascorbic acid in the mixed solution is 0.005M. Finally, Cu(OH)2nanotube array 2 loaded with Cu2O polyhedral particles on the foamed copper is prepared, denoted as Cu2O / Cu(OH)2NTA / CF-2.
[0037] Example 3
[0038] The embodiment provides a preparation method of Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface, and specific steps refer to those in the embodiment 1, and the only difference is that 0.4ml of 0.4M ascorbic acid solution is added in step S2, and the concentration of ascorbic acid in the mixed solution is 0.008M. Finally, Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface of foamed copper 3 is prepared, and is denoted as Cu2O / Cu(OH)2NTA / CF-3.
[0039] Embodiment 4
[0040] The embodiment provides a preparation method of Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface, and specific steps refer to those in the embodiment 1, and the only difference is that 0.5ml of 0.4M ascorbic acid solution is added in step S2, and the concentration of ascorbic acid in the mixed solution is 0.01M. Finally, Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface of foamed copper 4 is prepared, and is denoted as Cu2O / Cu(OH)2NTA / CF-4.
[0041] Embodiment 5
[0042] The embodiment provides a preparation method of Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface, and specific steps refer to those in the embodiment 1, and the only difference is that after the ascorbic acid solution is added in step S2, the foamed copper is taken out after 30 minutes of reaction. Finally, Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface of foamed copper 5 is prepared, and is denoted as Cu2O / Cu(OH)2NTA / CF-5.
[0043] Embodiment 6
[0044] The embodiment provides an application of the Cu(OH)2 nanotube array loaded with Cu2O polyhedral particles on the surface prepared in the embodiments 1-4, and the application specifically comprises the following steps:
[0045] 0.016g of KNO3 and 0.8713g of K2SO4 are added into 100ml of deionized water to configure a nitrate solution containing 50ppm of NO3 - ; the nitrate solution is used as an electrolyte, Cu2O / Cu(OH)2NTA / CF-1, Cu2O / Cu(OH)2NTA / CF-2, Cu2O / Cu(OH)2NTA / CF-3 and Cu2O / Cu(OH)2NTA / CF-4 prepared in the embodiments 1-4 are used as working electrodes, and Ag / AgCl is used as a reference electrode, and the nitrate is reduced under-1.2V negative bias voltage. 0.5ml of electrolyte is taken at intervals, and NO3 - , NO2 -and NH4 + .
[0046] The Cu2O / Cu(OH)2NTA / CF prepared in Example 1-4 were used in turn to reduce nitrate, and the test results of the content of nitrate in water are shown in turn in Figure 4 (a)-(d). It can be seen from Figure 4 that NO3 - is quickly reduced, and the content is significantly reduced within 2 hours, and the content of the toxic and harmful intermediate product NO2 - is significantly reduced relative to other reported catalytic materials, indicating the significant advantage of the composite structure in catalytic reduction of NO3 - .
[0047] Example 7
[0048] This example provides an application of the Cu(OH)2nanotube array loaded with Cu2O polyhedral particles prepared in Example 5, specifically comprising the following steps:
[0049] 0.016g KNO3, 0.8713g K2SO4 were added to 100ml deionized water to prepare a nitrate solution containing 50ppm NO3 - ; the nitrate solution was used as an electrolyte, Cu2O / Cu(OH)2NTA / CF-6 prepared in Example 6 was used as a working electrode, and Ag / AgCl was used as a reference electrode, and the nitrate was reduced under negative bias of-1.0, -1.2V, -1.4V, -1.6V in turn. 0.5ml of electrolyte was taken at intervals, and the content of NO3 - , NO2 - and NH4 + in the solution was detected by ion chromatography.
[0050] The Cu2O / Cu(OH)2NTA / CF prepared in Example 5 was used to reduce nitrate under different electrolysis voltages, and the test results of the content of nitrate in water are shown in turn in Figure 5 . It can be seen from Figure 5 that NO3 - is quickly reduced, and the content of the toxic and harmful NO2 - is significantly reduced relative to other reported catalytic materials, indicating the significant advantage of the composite structure in catalytic reduction of NO3 - . Among them, the effect of reducing nitrate under-1.2V negative bias is the best.
[0051] Those skilled in the art should understand that the above description is only several specific embodiments of the present application, not all embodiments. It should be noted that many modifications and improvements can also be made by those of ordinary skill in the art, and all modifications and improvements that do not exceed the scope of the claims should be considered as the protection scope of the present application.
Claims
1. A method for preparing Cu(OH)2 nanotube arrays surface-loaded with Cu2O polyhedral particles, characterized in that, The method comprises the following steps: S1, configuring 1-3M sodium hydroxide solution as electrolyte, using the cleaned foam copper as working electrode, platinum net as counter electrode, and mercury-mercury electrode as reference electrode, taking out the foam copper after anodic oxidation, rinsing and drying, and preparing Cu(OH)2 nanowire array on the foam copper, which is recorded as Cu(OH)2NWs / CF; S2, adding sodium hydroxide solution and polyvinylpyrrolidone into deionized water in sequence to obtain a mixed solution; heating and keeping the mixed solution, adding Cu(OH)2NWs / CF prepared in step S1 to fully soak, then adding weak reducing agent, taking out and rinsing and drying after 0.5-2 hours of reaction, and preparing Cu(OH)2 nanotube array with Cu2O polyhedral particle loaded on the surface on the foam copper, which is recorded as Cu2O / Cu(OH)2NTA.
2. The method of claim 1, wherein the Cu(OH)2nanotube array is prepared by the steps of: (a) preparing a Cu(OH)2nanotube array on a substrate; (b) immersing the Cu(OH)2nanotube array in a solution of Cu2O polyhedral particles; and (c) drying the Cu(OH)2nanotube array. In step S1, 10-30mA constant current is applied by an electrochemical workstation for 1-3h of anodic oxidation.
3. The method for preparing Cu(OH)₂ nanotube arrays with surface-loaded Cu₂O polyhedral particles according to claim 1, characterized in that, In the mixed solution of step S2, the concentration of sodium hydroxide is 0.01-0.1M, and the concentration of polyvinylpyrrolidone is 0.01-0.025g / ml.
4. The method of claim 2, wherein the Cu(OH)2nanotube array is prepared by the steps of: (a) preparing a Cu(OH)2nanotube array on a substrate; (b) immersing the Cu(OH)2nanotube array in a solution of Cu2O polyhedral particles; and (c) drying the Cu(OH)2nanotube array. In step S2, the mixed solution is heated to 45-65℃ and kept stable.
5. The method for preparing Cu(OH)₂ nanotube arrays with surface-loaded Cu₂O polyhedral particles according to claim 2, characterized in that, In step S2, the foam copper after anodic oxidation is soaked in the mixed solution for 1-3 hours.
6. The method for preparing Cu(OH)₂ nanotube arrays with surface-loaded Cu₂O polyhedral particles according to claim 1, characterized in that, In step S2, the weak reducing agent is one of ascorbic acid, glucose solution and polyhydric alcohol, and the concentration of the weak reducing agent added into the mixed solution is 0.003-0.01M.
7. A Cu(OH)2 nanotube array with Cu2O polyhedral particle loaded on the surface prepared by the method of any one of claims 1-6.
8. Use of Cu(OH)2 nanotube arrays surface-loaded with Cu2O polyhedral particles as electrocatalytic electrode material for the treatment of nitrate-contaminated water according to claim 7, characterized in that, containing 10-200 ppm NO3 - was used as electrolyte, Cu(OH)2nanotube array with Cu2O polyhedral particles loaded on the surface as working electrode, and Ag / AgCl as reference electrode. Nitrate was reduced at -1.0 to -1.6 V negative bias.
9. Use of Cu(OH)2nanotube arrays surface-loaded with Cu2O polyhedral particles according to claim 8, characterized in that, The nitrate is reduced under-1.2V negative bias.
10. Use of Cu(OH)2nanotube arrays loaded with Cu20 polyhedral particles according to claim 8 or 9, characterized in that, The reaction solution was taken as samples at intervals, and the NO3 in the solution was detected by ion chromatography. - NO2 - and NH4 + The content of.