A copper-based catalytic material for groundwater pollution remediation, a preparation method, a water treatment device and application of the copper-based catalytic material

Abstract

This invention belongs to the field of copper-based catalytic materials and water treatment technology, specifically relating to a solar thermal field-electrocatalytic synergistic copper-based catalytic material for groundwater pollution remediation, its preparation method, water treatment device, and application. This copper-based catalytic material utilizes the high catalytic activity of copper single atoms, the plasmon resonance effect of metal clusters, and the excellent H2O activation capacity of the CN substrate. Through photoexcitation, it generates a photothermal effect, significantly improving the mass transfer rate of H2O to the substrate and promoting the H2O dissociation reaction, efficiently generating protons and active hydrogen, driving electrochemical hydrogenation dehalogenation and NO3- dehalogenation. ‑ Electrocatalytic reduction. This process effectively solves the reaction kinetic limitations caused by the low proton transfer efficiency in traditional processes, significantly accelerates proton transport and optimizes the electron-proton synergistic transfer efficiency, providing a new approach for the research and development of synergistic treatment of organic and inorganic pollution in groundwater and sustainable development technologies, and has significant advantages in both environmental and energy conversion.

Description

Technical Field

[0001] This invention belongs to the field of copper-based catalytic materials and water treatment technology, specifically relating to a copper-based catalytic material with solar thermal field-electrocatalytic synergy for groundwater pollution remediation, its preparation method, water treatment device, and application. Background Technology

[0002] Currently used groundwater remediation technologies, such as reverse osmosis, electrodialysis, chemical reduction, and biofilm methods, generally suffer from high operating costs, secondary pollution risks, and long treatment cycles. In contrast, electrocatalysis technology is considered a promising approach for treating organic and inorganic groundwater pollution due to its simplicity, cleanliness, high efficiency, and lack of site limitations. This technology can precisely break the C–X bonds in HOPs at ambient temperature and pressure, and release NO3-. - It is reduced to harmless nitrogen (N2) or ammonia (NH3), which has energy value. In recent years, research has focused on the development of high-efficiency electrode materials. For example, the carbon nanotube-supported cobalt phthalocyanine catalyst (CoPc / CNT) prepared by Cheon et al. can efficiently degrade 2-chlorophenol by rapidly breaking its C-Cl bond (Neighboring Catalytic Sites Are Essential for Electrochemical Dechlorination of 2-Chlorophenol, Journal of the American Chemical Society, 2024, 146:25151-25157); the low mass transfer resistance electrocatalytic membrane electrode constructed by Fan et al. activates NO3 through interfacial defect sites. - It is then directionally reduced to N2, providing a new solution for the treatment of nitrate pollution in drinking water (Highly efficient metal-free nitrate reduction enabled by electrified membrane filtration, Nat. Water, 2024, 2: 684-696.). However, current research and development of electrocatalysis technology and related electrode materials mainly focuses on optimizing electron transfer efficiency, while the reduction of halogenated organic compounds and NO3... - The reduction and degradation of protons essentially depend on both electron transfer and proton addition. Existing systems generally lack effective control over the proton transport pathway, which limits the reaction kinetics and restricts the improvement of overall pollution remediation efficiency.

[0003] The core steps in the electrocatalytic reduction of both types of pollutants rely on the transfer of active hydrogen (H*). In the electrocatalytic system, H... *The only source is the H2O dissociation reaction (Volmer reaction: H2O + e-). + M → H * M + OH This reaction is limited by Volmer-Tafel kinetics. Theoretically, H* generated at the electrode interface migrates to the vicinity of the contaminant and can either replace halogen atoms on HOPs or participate in NO3. - Deoxygenation and proton addition are achieved through degradation. However, complex matrix components in groundwater, such as humic acid and potassium, contribute to degradation. + Na + Ca 2+ SO4² - These factors can significantly interfere with the generation and migration of H (Effects of ionic interferents on electrocatalytic nitrate reduction: Mechanistic insight, Environ. Sci. Technol., 2024, 58: 12823-12845.). For example, the steric hindrance of humic acid can hinder the migration of H to target pollutants, leading to their catalytic degradation via the Tafel reaction (H+). * + H * → H2) polymerization deactivation reduces proton utilization efficiency; while Ca² + Inorganic ions adsorbed on the electrode surface may cover catalytic active sites and cause electrode caking, thereby inhibiting H2O dissociation and the adsorption and degradation of pollutants. Furthermore, some high-performance electrocatalysts—such as the material disclosed in a Chinese patent application that co-loads Pt single atoms and clusters onto a NiCo layered bimetallic oxide—still have certain limitations. On the one hand, this method lacks sufficient control over the configuration of metal atoms; Pt is randomly distributed in the form of single atoms or clusters, making it difficult to achieve directional regulation to fully realize the material's potential. On the other hand, although this material exhibits excellent hydrogen evolution activity and stability in alkaline electrolytes, its dependence on the noble metal Pt also limits its large-scale application prospects.

[0004] Therefore, there is an urgent need for a new type of material that can improve the efficiency of proton transfer in the system and enhance the adsorption capacity of target reactants without relying on precious metals, so as to break through the existing technical bottlenecks and achieve efficient and sustainable groundwater remediation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of existing electrocatalytic materials, such as poor proton transfer efficiency or reliance on precious metals. The primary objective is to provide a copper-based catalytic material.

[0006] A second objective of this invention is to provide the application of the copper-based catalytic material in the preparation of electrode materials or photothermal conversion materials.

[0007] A third objective of this invention is to provide a material.

[0008] The fourth objective of this invention is to provide an electrolytic cell.

[0009] A fifth objective of the present invention is to provide the application of the copper-based catalytic material or the material or the electrolytic cell in the electrocatalytic treatment of wastewater.

[0010] The sixth objective of this invention is to provide a water treatment apparatus.

[0011] The above-mentioned objective of this invention is achieved through the following technical solution:

[0012] This invention protects a copper-based catalytic material, which is prepared by the following steps:

[0013] S1. Zinc salt, copper source and dimethylimidazole are mixed in the presence of the first organic solvent, reacted completely, and then post-treated to obtain solid Cu ZIF-8;

[0014] S2. The Cu ZIF-8 obtained in step S1 and melamine are thoroughly mixed, pyrolyzed at 450~650 ℃, and then post-treated to obtain solid Cu ZIF-8-NC;

[0015] S3. The Cu ZIF-8-NC obtained in step S2 and the metal salt are thoroughly mixed in the presence of the second organic solvent, the solid and liquid are separated, the precipitate is dried and carbonized at 800~1000 °C to obtain the copper-based catalyst material.

[0016] The ligand portion of the copper source is an organic compound;

[0017] The metal salt is selected from at least one of Cu, Al, Co, Fe, and Ni; copper-based catalytic materials prepared using these metals have good photothermal conversion performance.

[0018] The first organic solvent is more polar than the second organic solvent.

[0019] This invention develops a copper-based catalytic material, which is synthesized by a two-stage calcination strategy: First, by introducing melamine and pyrolyzing it at high temperature, a carbon-nitrogen precursor rich in nitrogen defects is constructed. These defects not only provide sites for subsequent metal anchoring but also lay the foundation for the final carbon-nitrogen (NC) network substrate. Second, the above-mentioned metal salt is used as a dopant metal source to load and form stable metal clusters on the defect-rich precursor. Specifically, a copper source is introduced during the self-assembly of Cu ZIF-8 to ensure the uniform dispersion of copper species; then, dopant metal is further loaded into the predetermined defect structure by chemical impregnation, and its limited dispersion is used to promote the generation of dopant metal clusters. This synthesis strategy achieves directional control of the microstructure of metal sites. The prepared copper-based catalytic material integrates three key functional sites: (1) Cu single atoms serve as the core active center, which efficiently adsorb halogenated organic pollutants (including but not limited to 2-chlorophenol) and NO3 by forming strong Cu-O bonds. - (1) Constructing directional electron transport channels; (2) Under illumination, doped metal clusters excite local surface plasmon resonance (LSPR), generating a micro-region high-temperature field near the reaction interface, which significantly accelerates the mass transfer rate of H2O and protons; (3) Due to its asymmetric electron distribution, the NC substrate effectively polarizes the adsorbed H2O molecules, greatly reducing the OH bond dissociation energy barrier and continuously generating active hydrogen species (H2O). * ), for the hydrodehalogenation of halogenated organic pollutants and NO3 - The material is gradually reduced to NH3, providing a sufficient proton source. This multi-active-site synergistic mechanism enables the material to efficiently and simultaneously remove organic and inorganic pollutants from groundwater in a thermoelectric catalytic system.

[0020] Furthermore, the metal salt or zinc salt includes its hydrate.

[0021] Preferably, the molar ratio of the zinc salt, copper source and dimethylimidazole is (10~15):1:(4~6), more preferably (12~14):1:(5~5.5).

[0022] Preferably, the preparation conditions of the copper-based catalytic material include one or more of (1) to (7):

[0023] (1) The copper source includes at least one of copper acetylacetonate, copper acetate, and copper tetraethyl cyanophosphate; ZIF-8 itself is a porous material composed of metal nodes and organic ligands; when the ligand part of the copper source used is organic, its organic part is closer to the organic ligands or pores of ZIF-8 in terms of physical and chemical properties; this better compatibility enables the metal precursor to achieve a more uniform initial distribution in ZIF-8;

[0024] (2) The mass ratio of Cu ZIF-8 to melamine is 1:(3~5);

[0025] (3) The molar ratio of Cu ZIF-8-NC to the metal salt is (4~7) g: 1 mmol;

[0026] (4) In step S2, the pyrolysis temperature is 500~600 ℃;

[0027] (5) In step S3, the carbonization temperature is 850~950 ℃;

[0028] (6) In step S1, the first organic solvent includes at least one of methanol and ethanol; the first organic solvent, including methanol and ethanol, has a high polarity, which is beneficial to the deprotonation process of 2-methylimidazole in the synthesis process with zinc salt.

[0029] (7) In step S3, the second organic solvent includes at least one of isopropanol and n-propanol. The second organic solvent, including isopropanol and n-propanol, has low polarity and will not damage the assembled ZIF-8 material structure when mixing materials with non-metallic salts.

[0030] Furthermore, the salt form of the metal salt includes at least one of nitrate and sulfate.

[0031] Furthermore, the molar ratio of Cu ZIF-8-NC to the metal salt is (5~6) g:1 mmol, more preferably (5.5~6) g:1 mmol.

[0032] Furthermore, in step S1, the temperature at which the reaction is fully completed is room temperature, typically 20±5 ℃.

[0033] Furthermore, in step S1, the time for the full reaction is 20-30 h, preferably 22-26 h.

[0034] Furthermore, in step S1, the mixing speed is 600~700 rpm / min.

[0035] Furthermore, in step S1, the post-processing includes solid-liquid separation, washing, and drying.

[0036] Furthermore, the solid-liquid separation involves placing the fully reacted mixed solution into a centrifuge device for solid-liquid separation.

[0037] Preferably, the centrifugation speed is 7000~8000 rpm / min.

[0038] Furthermore, the washing process involves repeated washing with a first organic solvent, preferably 2 to 3 times.

[0039] Furthermore, the drying is vacuum drying, and the vacuum drying temperature is preferably 60~70 ℃ (preferably 60~65 ℃), and the vacuum drying time is 6~15 h (preferably 8~12 h).

[0040] Preferably, in step S2, the heating rate of the pyrolysis is 1~10 ℃, more preferably 3~8 ℃.

[0041] Preferably, in step S2, the pyrolysis time is 2 to 4 hours, more preferably 2.5 to 3.5 hours.

[0042] Further, in step S2, the method of thorough mixing is ball milling, the ball milling speed is 100~300 rpm / min (preferably 150~250 rpm / min), and the ball milling time is 3~20 min (preferably 8~15 min).

[0043] Furthermore, in step S2, the post-processing includes grinding to ensure uniform particle size.

[0044] Preferably, in step S3, the heating rate of carbonization is 1~10 ℃, more preferably 3~8 ℃.

[0045] Preferably, in step S3, the carbonization time is 2 to 4 hours, more preferably 2.5 to 3.5 hours.

[0046] Furthermore, in step S3, the method of thorough mixing includes sonication and stirring, specifically sonication for 2-4 hours and stirring for 1-3 hours.

[0047] Furthermore, in step S3, the solid-liquid separation method is vacuum filtration.

[0048] Furthermore, the drying is vacuum drying, and the vacuum drying temperature is preferably 60~70 ℃ (preferably 60~65 ℃), and the vacuum drying time is 6~15 h (preferably 8~12 h).

[0049] This invention protects the application of the copper-based catalytic material in the preparation of electrode materials or photothermal conversion materials.

[0050] This invention protects a material, which is an electrode material or a photothermal conversion material, and the electrode material or photothermal conversion material is prepared from the copper-based catalytic material.

[0051] This invention protects an electrolytic cell, comprising an external power source, an anode, a cathode, and an electrolyte, wherein a catalyst is disposed on the cathode, and the catalyst comprises the copper-based catalytic material.

[0052] This invention protects the application of the copper-based catalytic material, or the material, or the electrolytic cell, in the electrocatalytic treatment of wastewater containing halogenated organic pollutants and NO3. - One or two of them.

[0053] Furthermore, the halogenated organic pollutants include at least one of 2-chlorophenol, pentachlorophenol, and 4-fluorophenol. Electrocatalytic dehalogenation technology replaces the halogen atoms (chlorine, fluorine) in the halogenated organic pollutants through a proton addition reaction, thereby achieving degradation.

[0054] Furthermore, the electrocatalysis includes photothermal-assisted electrocatalysis.

[0055] Furthermore, the concentration of the halogenated organic pollutant is ≥50 mmol / L, preferably 50~60 mmol / L.

[0056] Furthermore, the NO3 - The concentration is ≥20 mmol / L, preferably 20~30 mmol / L.

[0057] This invention also protects a water treatment device, comprising a water pump, an electrocatalytic reaction tank, and a treated water collection tank; the electrocatalytic reaction tank includes an electrolytic cell, the electrolytic cell includes an anode, a cathode, and an electrolyte located between the anode and the cathode; a catalyst is disposed on the cathode, the catalyst including the copper-based catalytic material;

[0058] The wastewater outlet of the water pump is connected to the wastewater inlet of the electrocatalytic reaction tank, and the wastewater outlet of the electrocatalytic reaction tank is connected to the wastewater inlet of the treated water collection tank.

[0059] Furthermore, it also includes a light collector, which is disposed on the cathode side of the electrocatalytic reaction cell and is used to focus light onto the cathode surface.

[0060] Furthermore, the treated water collection tank is equipped with a pH adjustment device and a rotary evaporator.

[0061] Furthermore, the sewage inlet of the water pump is connected to the sewage to be treated.

[0062] Furthermore, the wastewater to be treated is contaminated groundwater.

[0063] Furthermore, the wastewater to be treated contains halogenated organic pollutants and NO3. - One or two of them.

[0064] Furthermore, the halogenated organic pollutant includes at least one of 2-chlorophenol, pentachlorophenol, and 4-fluorophenol.

[0065] Furthermore, the outlet of the treated water collection tank is connected to the groundwater layer.

[0066] Furthermore, the treated water collection tank can be an ammonia salt collection tank.

[0067] Furthermore, the water pump is a high-pressure water pump.

[0068] Preferably, the light collector is a solar collector.

[0069] Compared with the prior art, the present invention has the following beneficial effects:

[0070] This invention provides a copper-based catalytic material for groundwater remediation using a solar thermal field-electrocatalytic synergy. The copper-based catalytic material utilizes the high catalytic activity of copper single atoms, the plasmon resonance effect of metal clusters, and the excellent H2O activation capacity of a carbon-nitrogen substrate. Through photoexcitation, it generates a photothermal effect, significantly enhancing the mass transfer rate of H2O to the substrate and promoting H2O dissociation reactions. This efficiently generates protons and active hydrogen, driving electrochemical hydrogenation dehalogenation and NO3- dehalogenation. - Electrocatalytic reduction. This process effectively solves the reaction kinetic limitations caused by the low proton transfer efficiency in traditional processes, significantly accelerates proton transport and optimizes the electron-proton synergistic transfer efficiency, providing a new approach for the synergistic treatment of organic and inorganic pollution in groundwater, and opening up new paths for the research and development of sustainable development technologies, with significant advantages in both environmental and energy conversion. Attached Figure Description

[0071] Figure 1 Cu1Cu was prepared for Example 1 x -NC fabrication process flow chart.

[0072] Figure 2 The images show the infrared spectrum and electron paramagnetic resonance spectrum of the Cu ZIF-8-NC material obtained in the second step of Examples 1-3, where Figure a is the infrared spectrum of the Cu ZIF-8-NC material obtained in the second step of Examples 1-3; and Figure b is the electron paramagnetic resonance spectrum of the Cu ZIF-8-NC material obtained in the second step of Examples 1-3.

[0073] Figure 3 These are scanning electron microscope images of the materials obtained at different stages in Example 1, where image a is the morphology of Cu ZIF-8 obtained in the first stage; image b is the morphology of Cu ZIF-8-550-NC obtained in the second stage; and image c is the morphology of Cu1Cu obtained in the third stage. x -Topographic diagram of NC.

[0074] Figure 4 The X-ray diffraction patterns are of the final materials obtained in Example 1 and Comparative Examples 1-2.

[0075] Figure 5 Cu1Cu obtained in Example 1 x - NC high-resolution spherical aberration transmission electron microscope images, where image a is a low-magnification overall view; image b is a high-magnification metal atom distribution map.

[0076] Figure 6 The X-ray photoelectron spectra of the final materials obtained in Examples 1 and Comparative Examples 1-2 are shown, where Figure a is the Cu 2p orbital spectrum and Figure b is the N 1s orbital spectrum.

[0077] Figure 7 The figures show linear sweep voltammetry diagrams of the final materials obtained in Example 1, Comparative Example 2, and Comparative Example 1, where figure a shows the final material Cu1Cu obtained in Example 1. x Figure a shows the linear scan voltammogram of the final material Cu1-NC obtained in Comparative Example 2 in the presence of 2-chlorophenol. Figure c shows the linear scan voltammogram of the final material Cu1-C obtained in Comparative Example 1 in the presence of 2-chlorophenol. Figure d shows the linear scan voltammogram of the final material Cu1Cu obtained in Example 1. x -NC in NO3 - Linear scanning voltammograms under the given conditions, e-plot shows the final material Cu1-NC obtained in Comparative Example 2 in NO3. - Linear scanning voltammograms under the given conditions, f-figure shows the final Cu1-C material obtained in Comparative Example 1 in NO3. - Linear sweep voltammogram under existing conditions.

[0078] Figure 8 Cu1Cu obtained in Example 1 x -Schematic diagram of the composition framework of NC materials.

[0079] Figure 9 Cu1Cu obtained in Example 1 x -Reaction mechanism diagram of NC materials.

[0080] Figure 10 The diagram shows the temperature changes of the final materials obtained in Example 1 and Comparative Examples 1-2.

[0081] Figure 11 The electrocatalytic NO3- of the final materials obtained in Example 1 and Comparative Example 1 - The performance data statistics of NH3 production are shown in Figure a, where Figure a is the Cu1Cu of Example 1. x - Statistical graph of NH3 yield data under no-light conditions for NC, Figure b shows Cu1Cu in Example 1. x -Statistical graph of NH3 yield data under illumination conditions for NC, Figure c shows Cu1Cu in Example 1. xFigure 1 shows the NO3 degradation rate of Cu1-C under light-free and light-illuminated conditions. Figure 2 shows the NH3 yield of Cu1-C in Comparative Example 1 under light-free conditions. Figure 3 shows the NH3 yield of Cu1-C in Comparative Example 1 under light-illuminated conditions. Figure 4 shows the NO3 degradation rate of Cu1-C in Comparative Example 1 under light-free and light-illuminated conditions.

[0082] Figure 12 This is a schematic diagram of a water treatment device for underground polluted water. Detailed Implementation

[0083] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0084] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0085] Example 1: Copper-based catalyst Cu1Cu x Preparation of -NC (550 °C)

[0086] Cu1Cu x -NC preparation process is as follows Figure 1 As shown, the specific steps include the following:

[0087] S1: First, prepare 100 mL of Zn(NO3)2 containing 40 mmol / L. A mixture of 6H₂O and 3 mmol / L Cu(acac)₂ in methanol, and 100 mL of 16 mmol / L dimethylimidazole in methanol were prepared. The two solutions were slowly mixed on a magnetic stirrer at 600 rpm / min. The mixed solution gradually changed from a transparent state to a white colloidal state. The mixture was stirred at 25°C for 24 hours. The mixture was then centrifuged at 7500 rpm / min for solid-liquid separation. During the separation stage, the solution was washed three times with methanol. The separated solid material was then placed in a vacuum drying oven and dried at 60°C for 12 hours, finally yielding a milky white solid, Cu ZIF-8.

[0088] S2: Prepare Cu ZIF-8 according to the method in step S1. Mix 600 mg of the obtained Cu ZIF-8 with 2.4 g of melamine and place them in a ball mill. Ball mill at 200 rpm / min for 10 min. Place the ball-milled mixture into a tube furnace and set the temperature to rise from 30 ℃ to 550 ℃ at a rate of 5 ℃ / min. Maintain the temperature at 550 ℃ for 3 hours for high-temperature pyrolysis. After the high-temperature pyrolysis is completed, a dark brown powder is obtained. Place the dark brown powder in a mortar and grind it manually to ensure uniform particle size. The resulting material is named Cu ZIF-8-550-NC.

[0089] S3: Add 600 mg of Cu ZIF-8-550-NC obtained in step S2 to 35 mL of isopropanol organic solution containing 3 mmol / L Cu(NO3)2. The mixture is sonicated for 3 hours and stirred for 2 hours to ensure homogeneity. Solid-liquid separation is performed by vacuum filtration, and the mixed material is dried in a vacuum drying oven (60 °C, 12 h). The dried powder is placed in a tube furnace, and the temperature is increased from 30 °C to 900 °C at a rate of 5 °C / min, and maintained at 900 °C for 3 hours for high-temperature carbonization, yielding a final black powder material named Cu1Cu. x -NC.

[0090] Example 2: Copper-based catalyst Cu1Cu x Preparation of -NC (450 °C)

[0091] The only difference from Example 1 is that the high-temperature pyrolysis temperature in step S2 is replaced by 450 ℃ instead of 550 ℃, and the material obtained in the second step is named Cu ZIF-8-450-NC.

[0092] The other steps and parameters are the same as in Example 1.

[0093] Example 3: Copper-based catalyst Cu1Cu x Preparation of -NC (650 °C)

[0094] The only difference from Example 1 is that the high-temperature pyrolysis temperature in step S2 is replaced by 650 ℃ instead of 550 ℃, and the material obtained in the second step is named Cu ZIF-8-650-NC.

[0095] The other steps and parameters are the same as in Example 1.

[0096] Comparative Example 1: Preparation of copper-based catalytic material Cu1-C

[0097] Compared with Example 1, the main difference is that Cu1-C is obtained by calcining Cu ZIF-8 directly at 900 °C in one step without introducing melamine nitrogen source.

[0098] The preparation method of Cu1-C specifically includes the following steps:

[0099] S1: First, prepare 100 mL of Zn(NO3)2 containing 40 mmol / L. A mixture of 6H₂O and 3 mmol / L Cu(acac)₂ in methanol, and 100 mL of 16 mmol / L dimethylimidazole in methanol were prepared. The two solutions were slowly mixed on a magnetic stirrer at 600 rpm / min. The mixed solution gradually changed from a transparent state to a white colloidal state. The mixture was stirred at 25°C for 24 hours. The mixture was then centrifuged at 7500 rpm / min for solid-liquid separation. During the separation stage, the solution was washed three times with methanol. The separated solid material was then placed in a vacuum drying oven and dried at 60°C for 12 hours, finally yielding a milky white solid, Cu ZIF-8.

[0100] S2: The Cu ZIF-8 prepared according to the method in step one is placed in a tube furnace, and the temperature is set to rise from 30 ℃ to 900 ℃ at a rate of 5 ℃ / min. The temperature is then maintained at 900 ℃ for 3 hours to carry out a high-temperature carbonization step, and the final black powder material is obtained, which is named Cu1-C.

[0101] Comparative Example 2: Preparation of copper-based catalyst Cu1-NC

[0102] Compared with Example 1, the main difference is that no Cu source was added in step S3, and its interface lacks a metal Cu cluster structure.

[0103] The preparation method of Cu1-NC specifically includes the following steps:

[0104] S1: First, prepare 100 mL of Zn(NO3)2 containing 40 mmol / L. A mixture of 6H₂O and 3 mmol / L Cu(acac)₂ in methanol, and 100 mL of 16 mmol / L dimethylimidazole in methanol were prepared. The two solutions were slowly mixed on a magnetic stirrer at 600 rpm / min. The mixed solution gradually changed from a transparent state to a white colloidal state. The mixture was stirred at 25°C for 24 hours. The mixture was then centrifuged at 7500 rpm / min for solid-liquid separation. During the separation stage, the solution was washed three times with methanol. The separated solid material was then placed in a vacuum drying oven and dried at 60°C for 12 hours, finally yielding a milky white solid, Cu ZIF-8.

[0105] S2: Prepare Cu ZIF-8 according to the method in step S1. Mix 600 mg of the obtained Cu ZIF-8 with 2.4 g of melamine and place them in a ball mill. Ball mill at 200 rpm / min for 10 min. Place the ball-milled mixture into a tube furnace and set the temperature to rise from 30 ℃ to 550 ℃ at a rate of 5 ℃ / min. Maintain the temperature at 550 ℃ for 3 hours for high-temperature pyrolysis. After the high-temperature pyrolysis is completed, a dark brown powder is obtained. Place the dark brown powder in a mortar and grind it manually to ensure uniform particle size. The resulting material is named Cu ZIF-8-550-NC.

[0106] S3: 600 mg of Cu ZIF-8-550-NC obtained in step S2 was poured into 35 mL of isopropanol organic solution. The mixture was sonicated for 3 hours and stirred for 2 hours to ensure homogeneity. Solid-liquid separation was performed by vacuum filtration, and the mixed material was placed in a vacuum drying oven for drying. The dried powder was placed in a tube furnace, and the temperature was increased from 30 °C to 900 °C at a rate of 5 °C / min, and maintained at 900 °C for 3 hours for high-temperature carbonization, yielding a final black powder material, named Cu1-NC.

[0107] Performance Characterization of Experimental Examples

[0108] (1) Infrared spectroscopy test

[0109] In the first step (step S1) of low-temperature calcination, melamine undergoes a deamination reaction (-NH2) to generate an intermediate condensation product, which further condenses to form a graphite-like carbon nitride (g-C3N4) structure. The Cu ZIF-8-NC material obtained in the second step (step S2) of Examples 1-3 was characterized by infrared spectroscopy, and the results are as follows: Figure 2 As shown in Figure a, all three Cu ZIF-8-NC materials prepared at different temperatures exhibit g-C3N4-like signals in the characteristic band. Among them, the Cu ZIF-8-550-NC prepared in Example 1 exhibits the strongest g-C3N4-like signal in the characteristic band, confirming that calcination at 550 ℃ is most favorable for the formation of abundant g-C3N4-like structures at the material interface. This structure lays the foundation for the subsequent high-temperature calcination to form a stable carbon-nitrogen network (NC) substrate.

[0110] (2) Electron paramagnetic resonance test

[0111] Further electron paramagnetic resonance (EPR) tests were performed on the Cu ZIF-8-NC materials obtained in the second step of Examples 1-3, and the results are as follows: Figure 2As shown in Figure b, a significant nitrogen defect signal was detected at g = 2.003, especially in Cu ZIF-8-550-NC, indicating that it is rich in nitrogen defect sites, providing sufficient anchoring points for the subsequent formation of metallic Cu clusters.

[0112] (3) Scanning electron microscopy test

[0113] Scanning electron microscopy was used to test the materials synthesized at different stages in Example 1. The results are as follows: Figure 3 As shown, the Cu ZIF-8 obtained in the first stage ( Figure 3 Figure a) shows a typical dodecahedral morphology, confirming the successful construction of a ZIF-8 type metal-organic framework. After calcination at 550 ℃, the Cu ZIF-8-550-NC obtained in the second step (…) Figure 3 As shown in Figure b, topological collapse occurs, forming irregular particles. The mechanism lies in the reducing NH3 gas released during the deamination and polycondensation of melamine, which induces partial carbonization of the framework and generates the aforementioned nitrogen defects. This nitrogen defect engineering not only promotes atomic-level dispersion of Cu species but also creates active sites for metal cluster anchoring. After calcination at 900 °C, the third step (step S3) yields Cu1Cu. x -NC ( Figure 3 Figure c) shows a porous structure with high-density Cu-N x Single atomic sites and surface Cu clusters form a synergistic catalytic interface.

[0114] (4) X-ray diffraction test

[0115] X-ray diffraction tests were performed on the final materials obtained in Example 1 and Comparative Examples 1-2, and the results are as follows: Figure 4 As shown, the comparison results indicate that the Cu1Cu obtained in Example 1... x -NC exhibits significant Cu crystal plane diffraction peaks, confirming the presence of metallic Cu clusters in the material.

[0116] (5) High-resolution transmission electron microscopy test with spherical aberration correction

[0117] Cu1Cu obtained in Example 1 x -NC performed aberration-corrected high-resolution transmission electron microscopy tests, further revealing the fine structure of the material, as shown in the results. Figure 5 As shown, Figure 5 Figure a shows Cu1Cu x -NC has a thinner, irregular morphology. Figure 5 The high-density bright spots observed at the interface in Figure b represent heavy element Cu atoms, confirming the existence of Cu units. Their distribution characteristics clearly show that the material has both Cu single-atom and Cu cluster configurations.

[0118] (6) X-ray photoelectron spectroscopy analysis

[0119] To investigate the structural evolution of the catalyst during synthesis, the Cu ZIF-8-NC prepared in Example 1 and its product after high-temperature carbonization and pyrolysis (i.e., Cu1Cu) were compared. x X-ray photoelectron spectroscopy analysis was performed on the NC (Number of NC) sample, and the results are as follows: Figure 6 As shown in Figure a, after the third step of carbonization, the characteristic peaks corresponding to the Zn element in the material completely disappeared, indicating that the Zn species had been effectively volatilized or removed during the pyrolysis process, thus successfully realizing the transformation from metal-organic framework to carbon-based catalytic material.

[0120] To investigate the chemical state evolution of Cu and the formation of the carbon-nitrogen network substrate, X-ray photoelectron spectroscopy analysis was performed on the final materials obtained in Example 1 and Comparative Examples 1-2. The results are as follows: Figure 6 As shown in Figure b, Cu1Cu x -NC low valence state (Cu) + / Cu 0 The proportion of Cu is significantly higher. 0 The state mainly originates from metal clusters. Figure 6 Figure c confirms that the materials synthesized with melamine (Cu1-NC and Cu1Cu) x The abundant pyridine nitrogen, graphitic nitrogen, and Cu-N bond signals of the -NC matrix strongly support the successful construction of stable carbon-nitrogen network (NC) substrates.

[0121] (7) Testing of the pollution catalytic performance of materials

[0122] 1. Experimental Methods

[0123] The catalytic performance of the material was tested using linear sweep voltammetry (LSV). LSV was conducted in a sealed, two-chamber H-type reactor connected to a CHI-760E electrochemical workstation. The anode and cathode chambers were separated by a Nafion 117 proton exchange membrane, which required pretreatment before use: immersion in hydrogen peroxide solution at 80°C for 1 hour. Each chamber contained 50 mL of electrolyte. Electrocatalytic experiments were performed using a three-electrode system. A platinum sheet counter electrode was placed in the anode chamber, while the cathode chamber was equipped with an Ag / AgCl reference electrode and a working electrode. The working electrode was prepared by coating the catalyst (i.e., the final material obtained in Example 1, Comparative Example 1, or Comparative Example 2) with ink onto hydrophilic carbon paper. The catalyst ink was prepared by dispersing 3.0 mg of catalyst in a mixture of 470 μL deionized water, 500 μL methanol, and 30 μL Nafion solution, followed by ultrasonic treatment for 1 hour to achieve uniform dispersion. The resulting uniform ink was then coated onto a carbon paper substrate and dried at room temperature. The supporting electrolyte used in this experiment was a 500 mmol / L Na₂SO₄ solution. A xenon lamp (PLS-SXE300D, Beijing Pofilai Technology Co., Ltd.) equipped with an AM 1.5 G filter was used to simulate the solar light source. Light intensity was measured using a full-spectrum optical power meter (CEL-NP2000, Beijing Zhongjiao Jinyuan Technology Co., Ltd.). During the photoelectrolysis process, the irradiance was maintained at a constant 400 mW·cm⁻¹. - ²; The anode chamber is continuously stirred at a speed of 400 rpm to enhance mass transfer.

[0124] LSV was tested in the range of 0.1 V to -0.9 V vs. RHE potential, at a scan rate of 5 mV·s. - ¹, and applied 90% iR compensation. Before the test, 50 mmol / L 2-chlorophenol or 20 mmol / L sodium nitrate were added to the electrolyte as target contaminants. To eliminate interference from dissolved oxygen, high-purity nitrogen was continuously purged into the electrolyte for 30 minutes before the test to remove oxygen, followed by sealed measurement.

[0125] 2. Experimental Results

[0126] A three-electrode system was used to evaluate the final materials obtained in Example 1 and Comparative Examples 1-2 in a simulated high-salinity groundwater environment (containing 50 mmol / L 2-chlorophenol / 20 mmol / L NO3). - The catalytic performance of the contaminant in a 0.5 mol / L Na₂SO₄ solution was specifically investigated using linear sweep voltammetry, and the results are as follows: Figure 7 As shown in Figure a, under near-infrared light irradiation, Cu1Cu xThe current density of -NC significantly increased with illumination time at -0.8 V vs. RHE potential, increasing from 18.8 mA / cm² to 75.2 mA / cm². This phenomenon is attributed to the photothermal effect inducing a high-temperature micro-field at the catalytic interface, which greatly accelerated the kinetics of the 2-chlorophenol reduction reaction. Comparative experiments highlight the criticality of the synthesis strategy, with Comparative Example 1 using Cu1-C ( Figure 7 Figure c in the diagram) and Cu1-NC in Comparative Example 2 ( Figure 7 (Figure b) Under the same illumination conditions, the current density increase is less than 10%. Similarly, the Cu1Cu obtained in Example 1... x -NC under 20 min of infrared light irradiation, the system's effect on NO3 - The electrocatalytic activity was also significantly improved. Figure 7 (Figure d in the diagram), while Cu1-C in Comparative Example 1 ( Figure 7 Figure f in Comparative Example 2 and Cu1-NC ( Figure 7 The catalytic activity of Cu1Cu obtained in Example 1 was not significantly enhanced under light irradiation (Figure e). This result fully demonstrates that the catalytic activity of Cu1Cu obtained in Example 1 is not significantly enhanced under light irradiation. x The synergistic effect of Cu single-atom sites (efficiently catalyzing pollutants), Cu clusters (photothermal-driven mass transfer / proton migration), and the NC substrate (promoting H2O dissociation and proton donation) in NC is the core mechanism for its significantly enhanced electrocatalytic activity.

[0127] Cu1Cu x The mechanism by which -NC exhibits excellent catalytic performance is explained as follows: Figure 8 As shown, Cu1Cu x The NC material is prepared via a two-stage calcination method: First, melamine is used as a nitrogen source to construct a nitrogen-deficient carbon-nitrogen network substrate (NC); then, these nitrogen defects are used to anchor metal (M) clusters exhibiting localized surface plasmon resonance (LSPR) effects (M here is Cu, but not limited to Cu, and can also be Al, Co, Fe, Ni). In the catalytic system, Cu single-atom sites efficiently capture pollutants; the M metal clusters drive interfacial water molecule mass transfer and proton migration through photothermal effects; and the NC substrate promotes H2O dissociation reactions, continuously providing a proton source for the reductive degradation of pollutants. This synergistic effect of the functions of Cu single-atom sites, M metal clusters, and the NC substrate significantly improves the catalyst's degradation performance for the target pollutants.

[0128] As can be seen, the single-atom / cluster coexistence type Cu1Cu synthesized in this invention x -NC materials, based on nitrogen-doped carbon networks (NC), significantly improve the mass transfer efficiency and electron transport kinetics of the electrocatalytic interface through synergistic design of active sites and substrate functions, enabling the extraction of 2-chlorophenol (an organic pollutant) and NO3 from groundwater.- Efficient and simultaneous degradation of (inorganic pollutants). For example... Figure 9 As shown, Cu single atoms serve as core active sites, forming stable directional electron transport channels through strong Cu-O bonds with pollutants; Cu x Metal clusters, under illumination, excite localized surface plasmon resonance, generating a micro-regional high-temperature field at the reaction interface, significantly accelerating H2O and proton mass transfer. The asymmetric electron distribution of the NC substrate effectively polarizes the OH bonds of adsorbed H2O, significantly reducing the water dissociation energy barrier and continuously generating H2O. * The hydrogenation dehalogenation of 2-chlorophenol and NO3 - Gradual reduction to NH3 provides a sufficient proton source. This active site (Cu single atom and Cu...) x The synergistic effect of clusters and functionalized substrates (NC) enables the catalyst to efficiently remove organic-inorganic composite pollutants in complex aquatic environments.

[0129] (8) Testing of the photothermal conversion performance of materials

[0130] 1. Experimental Methods

[0131] The photothermal conversion performance of the material was tested in a sealed dual-chamber H-type reactor. The test system (including the three-electrode system, electrolyte, and CHI-760E electrochemical workstation) was consistent with the experimental method used in the pollution catalytic performance test of the material mentioned in (7). The temperature of the reaction solution was detected in situ using an infrared thermal imaging monitor during the reaction process.

[0132] ammonia nitrogen (NH4) in the reaction solution + ) and nitrate (NO3) - The concentrations of NH4 were determined using ultraviolet-visible spectrophotometry, based on pre-established standard curves. + Determination: First, prepare solution A (a 1 mol / L NaOH solution containing 5 wt% salicylic acid and 5 wt% sodium citrate). Take 2 mL of the test solution, add 2 mL of solution A, 1 mL of 0.05 mol / L NaClO solution, and 200 μL of 1 wt% sodium nitrosoferricyanide dihydrate (Na2[Fe(NO)(CN)5]) solution sequentially. After thorough stirring, let it stand at room temperature in the dark for 2 h, and measure the absorbance at a wavelength of 650 nm. - Determination: Take 2 mL of sample, dilute to 5 mL with deionized water, then add 0.1 mL of 1 mol / L HCl and 0.01 mL of 0.8 wt% aminosulfonic acid solution, mix thoroughly, and let stand at room temperature for 20 min. Measure the absorbance at 220 nm and 275 nm respectively, and calculate using the formula A = A 220 – 2A 275Calculate the corrected absorbance.

[0133] Electrocatalysis of NO3 - In the reduction experiment, the calculation methods for key performance parameters are as follows, including NO3. - Conversion rate ( E NO3 ), NH4 + Yield ( R NH3 Faraday electron utilization efficiency (FE):

[0134]

[0135] In Formula 1, C 0,NO3 With C t, NO 3 These represent the initial moment of the reaction and the reaction time, respectively. t hour NO 3 - concentration (mmol·L) - ¹); In Formula 2, [NH3] is the concentration of NH3 (mmol·L). - ¹), V The volume of the reaction system is (L). m cat Catalyst mass (mg) M The molar mass of NH3 (g·mol) - ¹), t The reaction time is given in hours (h); in Formula 3, F is the Faraday constant (96485.3 C·mol⁻¹). - ¹), where n is the number of electrons transferred in the reaction (e.g., 8 for the synthesis of NH3, and 8 for the production of NO2). - (2), c is the product concentration (mol·L) - ¹), V is the reaction volume (L), I is the current (A) in the electrocatalytic process, and t is the reaction time (s).

[0136] 2. Experimental Results

[0137] Cu1Cu x -NC electrode materials exhibit excellent photothermal conversion performance. Under near-infrared light irradiation, the materials can efficiently convert light energy into heat energy, establishing a significant localized temperature field at the reaction interface. For example... Figure 10 As shown in the comparative experiment, it is clear that after 20 min of reaction, the Cu1Cu prepared in Example 1... x The solution temperature of the NC-constructed system can reach above 40 °C; while the temperature of other control group materials only remains at about 34 °C. This directly confirms the Cu1Cux -The photothermal effect of metal clusters in NC is the key contribution to the temperature rise of the system.

[0138] Based on Cu1Cu x The photoelectrochemically coupled catalytic system constructed by -NC exhibits excellent comprehensive performance in treating simulated groundwater nitrate pollution, as shown in the results. Figure 11 As shown in a~b, after introducing a near-infrared light field ( Figure 11 As shown in Figure b), the NH3 yield was significantly improved under different applied potentials. Especially at a potential of -0.8 V (vs. RHE), the NH3 yield reached a peak of 9934.1 μg h⁻¹. - ¹ cm - ², Darker field conditions ( Figure 11 The efficiency of the reaction was increased by 2.0 times (Figure a). The synergistic effect of the light field also increased the Faraday efficiency of the reaction to over 75%, confirming that the photothermal effect effectively suppressed the competitive hydrogen evolution reaction and optimized the electron transport pathway to preferentially utilize NO3. - Reduction. Furthermore, the introduction of a light source significantly improved the system's resistance to NO3. - degradation efficiency ( Figure 11 (Figure c). Comparative experiment of Cu1-C in Comparative Example 1 ( Figure 11 The d~f diagram further highlights the Cu1Cu of the embodiment. x - Advantages of NC material design: Traditional Cu1-C materials show no significant performance change under the same light field conditions, with an NH3 yield increase of less than 8% and a Faraday efficiency consistently below 50%. Cu1Cu x The unique structural design in NC enables efficient photothermal synergistic electrocatalytic reduction of NO3. - The production of NH3 generates economic benefits.

[0139] (9) Based on Cu1Cu x - Practical Application of NC Water Treatment Device in Groundwater Pollution Areas

[0140] Based on Cu1Cu x -See NC water treatment equipment Figure 12 The water treatment device mainly includes a water pump 1, a solar collector 2, an electrocatalytic reaction tank 3, and a treated water collection tank 4.

[0141] The electrocatalytic reaction tank 3 is the core processing unit, and it contains an electrolytic cell 5. The electrolytic cell 5 includes an external power source 6, an anode 7, a cathode 8, and an electrolyte 9 filling the space between the electrodes. A catalyst is mounted on the cathode 8, and the catalyst is any one of the copper-based catalytic materials Cu1Cu prepared in Examples 1-3. x -NC, a low-cost, high-conductivity carbon plate is used as the anode 7 to form a pair of electrode systems.

[0142] The connections between the components are as follows:

[0143] The water pump 1's inlet is connected to the groundwater pollution source via the first pipe 10, and its outlet is connected to the sewage inlet at the bottom of the electrocatalytic reaction tank 3 via the second pipe 11.

[0144] The wastewater outlet at the bottom of the electrocatalytic reaction tank 3 is connected to the inlet of the treated water collection tank 4 via a third pipeline 12.

[0145] The solar collector 2 is fixedly installed outside the electrocatalytic reaction tank 3 and faces the surface of the cathode 8 inside, so as to concentrate sunlight and irradiate the cathode 8.

[0146] The treated water collection tank 4 integrates a pH adjustment device and a rotary evaporator. Its purified water outlet is connected to the groundwater layer via a fourth pipeline 13 for reinjecting treated water that meets the standards.

[0147] The work process is as follows:

[0148] The system is started, and pump 1 continuously extracts water containing high concentrations of pollutants (such as 2-chlorophenol and NO3) from the groundwater pollution fault. - The polluted water is pumped into the electrocatalytic reaction tank 3 via the first sewage pipeline 10. An external electric field is applied to both ends of the electrolytic cell 5. When the sewage flows over the surface of the cathode 8, an electrocatalytic reduction reaction occurs under the action of the electric field, and the pollutant molecules gain electrons and are reduced and degraded.

[0149] Simultaneously, the solar collector 2 concentrates sunlight onto the surface of the cathode 8. The light excites the cathode material surface, significantly improving the degradation rate and efficiency of pollutants. With the occurrence of efficient reduction reactions at the cathode interface, pollutants in the water, such as 2-chlorophenol and NO3, are degraded. - Pollutants are continuously degraded.

[0150] After undergoing photothermal synergistic electrocatalysis and treatment, the water flows into the treated water collection tank 4 through the second sewage pipeline 12.

[0151] In the treated water collection tank 4, the pH of the solution is first adjusted by a pH adjustment device, and the treated products, such as ammonium salts, are collected and utilized through the rotary evaporation of a rotary evaporator. Finally, the treated water that meets the standards is pumped back into the groundwater layer through the fourth pipeline 13, completing the in-situ remediation cycle.

[0152] In summary, the copper-based catalyst Cu1Cu of this invention... xUsing NC as the core catalyst, this method couples electrochemical reduction with photocatalysis, utilizing the photothermal effect of the material to convert light energy into heat energy, further improving electrocatalytic efficiency and reducing overall energy consumption. Simultaneously, through a subsequent product recovery unit, it achieves the dual goals of pollutant degradation and resource recovery, making it particularly suitable for pollutants containing halogenated organic pollutants and NO3. - Groundwater pollution control.

[0153] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A copper-based catalytic material, characterized in that, The preparation process includes the following steps: S1. Zinc salt, copper source and dimethylimidazole are mixed in the presence of the first organic solvent, reacted completely, and then post-treated to obtain solid Cu-ZIF-8. S2. Thoroughly mix Cu-ZIF-8 obtained in step S1 with melamine, pyrolyze at 450~650 ℃, and then perform post-treatment to obtain solid Cu-ZIF-8-NC; S3. The Cu-ZIF-8-NC obtained in step S2 and the metal salt are thoroughly mixed in the presence of the second organic solvent, the solid and liquid are separated, the precipitate is dried and carbonized at 800~1000 °C to obtain the copper-based catalyst material. The ligand portion of the copper source is an organic compound; The metal in the metal salt is selected from at least one of Cu, Co, Fe, and Ni; The first organic solvent is more polar than the second organic solvent.

2. The copper-based catalytic material according to claim 1, characterized in that, The molar ratio of the zinc salt, copper source and dimethylimidazole is (10~15):1:(4~6).

3. The copper-based catalytic material according to claim 1 or 2, characterized in that, The preparation conditions of the copper-based catalyst material include one or more of (1) to (7): (1) The copper source includes at least one of copper acetylacetonate, copper acetate, and copper tetraethyl cyanophosphate; (2) The mass ratio of Cu-ZIF-8 to melamine is 1:(3~5); (3) The molar ratio of Cu-ZIF-8-NC to the metal salt is (4~7) g: 1 mmol; (4) In step S2, the pyrolysis temperature is 500~600 ℃; (5) In step S3, the carbonization temperature is 850~950 ℃; (6) In step S1, the first organic solvent includes at least one of methanol and ethanol; (7) In step S3, the second organic solvent includes at least one of isopropanol and n-propanol.

4. The application of the copper-based catalytic material according to any one of claims 1 to 3 in the preparation of electrode materials or photothermal conversion materials.

5. A material, characterized in that, The material is an electrode material or a photothermal conversion material, which is prepared from the copper-based catalytic material according to any one of claims 1 to 3.

6. An electrolytic cell, comprising an external power source, an anode, a cathode, and an electrolyte, characterized in that, The cathode is provided with a catalyst, which includes the copper-based catalytic material according to any one of claims 1 to 3.

7. The application of the copper-based catalytic material according to any one of claims 1 to 3, or the material according to claim 5, or the electrolytic cell according to claim 6, in the electrocatalytic treatment of wastewater, characterized in that, The wastewater contains halogenated organic pollutants and NO3. - One or two of them.

8. The application according to claim 7, characterized in that, The halogenated organic pollutants include at least one of 2-chlorophenol, pentachlorophenol, and 4-fluorophenol.

9. A water treatment device, characterized in that, The system includes a water pump (1), an electrocatalytic reaction tank (3), and a treated water collection tank (4); the electrocatalytic reaction tank (3) is equipped with an electrolytic cell (5), the electrolytic cell (5) includes an external power supply (6), an anode (7), a cathode (8), and an electrolyte (9) located between the anode (7) and the cathode (8); the cathode (8) is provided with a catalyst, the catalyst including the copper-based catalytic material according to any one of claims 1 to 3; The sewage outlet of the water pump (1) is connected to the sewage inlet of the electrocatalytic reaction tank (3), and the sewage outlet of the electrocatalytic reaction tank (3) is connected to the sewage inlet of the treated water collection tank (4).

10. The water treatment apparatus according to claim 9, characterized in that, It also includes a light collector (2), which is disposed on the cathode (8) side of the electrocatalytic reaction cell (3) for focusing light onto the cathode (8) surface.

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