Surface amorphous modified copper-based chalcogenide nanomaterial array and application

Abstract

This invention belongs to the field of wastewater treatment technology, specifically relating to a surface-modified copper-based chalcogenide nanoarray material and its application. Using a copper-based current collector as a carrier, the invention obtains a surface-modified copper-based chalcogenide nanoarray material through a high-temperature gas-solid conversion reaction and subsequent calcination amorphous modification. This material exhibits excellent ammonia production rate, high Faradaic efficiency, and good long-term operational stability in the electrocatalytic reduction of nitrate to ammonia. When further coupled with sulfur oxidation or methanol oxidation reactions, it also possesses excellent electrocatalytic activity and stability, significantly reducing energy consumption in wastewater resource recovery processes and demonstrating good environmental and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology. More specifically, it relates to a surface-modified copper-based chalcogenide nanoarray material and its application. Background Technology

[0002] Electrocatalytic nitrate reduction to ammonia (NO3RR) can achieve the reduction of nitrate (NO3) in wastewater at room temperature and pressure. - The directed conversion of ) into ammonia (NH3, which in acidic or neutral liquids is NH4) + (It exists in form) to realize the resource utilization of wastewater. However, this process is usually limited by the slow kinetics and high overpotential of the oxygen evolution reaction (OER), resulting in high overall energy consumption and limiting its large-scale application.

[0003] In recent years, bifunctional electrocatalytic systems that couple NO3RR with anodic sulfur oxidation (SOR) or methanol oxidation (MOR) have attracted widespread attention. These bifunctional systems introduce nitrate-containing wastewater to the cathode and sulfur-containing wastewater (such as wastewater from papermaking, leather tanning, and dyeing industries) or methanol-containing wastewater (such as wastewater from chemical and pharmaceutical industries) to the anode, simultaneously achieving ammonia production at the cathode and the generation of elemental sulfur or formic acid through anodic oxidation, thereby realizing the resource recovery of pollutants.

[0004] Copper-based materials due to the d orbital energy level and NO3 - High orbital matching and readily available, inexpensive raw materials make copper-based materials the mainstream non-precious metal catalysts for NO3RR. However, copper-based materials exhibit reduced activity sites (Cu) under negative potential conditions. + It is easily reduced to Cu 0 This leads to rapid decay of electrode catalytic activity and poor stability; when used as an electrocatalytic material in a bifunctional electrocatalytic coupling system, it is even more difficult to maintain anodic oxidation activity, resulting in excessively high overall energy consumption.

[0005] Therefore, developing a copper-based electrocatalytic material with both high-efficiency reduction and oxidation catalytic activity, excellent long-term stability and low energy consumption, and applying it to a bifunctional coupling system to achieve simultaneous and efficient catalysis at the anode and cathode, is of great practical significance for the resource utilization of wastewater. Summary of the Invention

[0006] This invention addresses the problem that existing copper-based electrocatalytic materials cannot simultaneously meet the comprehensive performance requirements of efficient simultaneous catalysis at both the anode and cathode in a bifunctional coupling system, possessing both reduction and oxidation dual-function activity, long-term stability, and low energy consumption. The aim is to provide a surface-modified copper-based chalcogenide nanoarray material.

[0007] A second objective of this invention is to provide a dual-function system.

[0008] A third objective of this invention is to provide the application of the aforementioned surface-modified copper-based chalcogenide nanoarray material in electrocatalytic nitrate reduction to ammonia production and / or oxidation reactions.

[0009] A fourth objective of this invention is to provide the application of the bifunctional system in the electrocatalytic reduction of nitrate to ammonia and oxidation reactions.

[0010] The fifth objective of this invention is to provide a method for simultaneously treating wastewater containing sulfur ions and wastewater containing nitrates.

[0011] The sixth objective of this invention is to provide a method for simultaneously treating methanol-containing wastewater and nitrate-containing wastewater.

[0012] The above-mentioned objective of this invention is achieved through the following technical solution: This invention provides a surface-modified copper-based chalcogenide nanoarray material, which is prepared by the following steps: S1: Mix the copper-based current collector with the gas-solid conversion source material, place it in a reducing gas atmosphere, and carry out a high-temperature gas-solid conversion reaction at 500~700 ℃ to obtain a crystalline copper-based chalcogenide nanoarray material loaded on the copper-based current collector. S2: The crystalline copper-based chalcogenide nanoarray material loaded on the copper-based current collector obtained in step S1 is placed in an air atmosphere and calcined for 2-4 hours until its surface part is transformed into an amorphous state, thereby obtaining the surface amorphous modified copper-based chalcogenide nanoarray material. The gas-solid conversion source material is sulfur powder, selenium powder, or tellurium powder; The mass ratio of the copper-based current collector to the gas-solid conversion source material is 1:(10~50).

[0013] In step S2, the calcination satisfies the following conditions: (1) When the gas-solid conversion source material is sulfur powder, the calcination temperature is 340~360 ℃; (2) When the gas-solid conversion source material is selenium powder, the calcination temperature is 440~460 ℃; (3) When the gas-solid conversion source material is tellurium powder, the calcination temperature is 240~260 ℃.

[0014] Preferably, the copper-based current collector is selected from at least one of copper foam, copper mesh, copper plate, and copper sheet.

[0015] More preferably, the copper-based current collector is pretreated.

[0016] More preferably, the pretreatment is ultrasonic cleaning, specifically, ultrasonic cleaning in 2 M hydrochloric acid, anhydrous ethanol, and deionized water for 10 min each.

[0017] In a preferred embodiment, when the gas-solid conversion source material is sulfur powder, the calcination temperature is 345~355 ℃ and the calcination time is 2.5~3 h.

[0018] In a preferred embodiment, when the gas-solid conversion source material is selenium powder, the calcination temperature is 445~455 ℃ and the calcination time is 2~2.5 h.

[0019] In a preferred embodiment, when the gas-solid conversion source material is tellurium powder, the calcination temperature is 245~255 ℃ and the calcination time is 3.5~4 h.

[0020] Preferably, the high-temperature gas-solid conversion reaction takes 4 to 8 hours.

[0021] Preferably, the heating rate of the high-temperature gas-solid conversion reaction is 4~10 °C / min.

[0022] Preferably, the reducing gas atmosphere contains hydrogen.

[0023] More preferably, the reducing gas atmosphere also contains a protective gas.

[0024] More preferably, the protective gas is selected from at least one of nitrogen, argon, and helium.

[0025] More preferably, the volume ratio of hydrogen to protective gas is 5:(90~100).

[0026] Preferably, the calcination time is 2-4 hours.

[0027] Preferably, the heating rate of the calcination is 2~6 °C / min.

[0028] The present invention also provides a dual-function system, which includes a power source, a diaphragm, a cathode, an anode, a cathode chamber, and an anode chamber, wherein the materials of the anode and the cathode both contain the surface-layer amorphous modified copper-based chalcogenide nanoarray material.

[0029] The present invention also provides the application of the surface amorphous modified copper-based chalcogenide nanoarray material in electrocatalytic nitrate reduction to ammonia production and / or oxidation reactions, wherein the oxidation reaction is at least one of sulfur oxidation reaction and methanol oxidation reaction.

[0030] The present invention also provides the application of the bifunctional system in the electrocatalytic reduction of nitrate to ammonia and oxidation reactions, wherein the oxidation reaction is at least one of sulfur oxidation and methanol oxidation.

[0031] Furthermore, the electrocatalytic nitrate reduction reaction (NO3RR) described in this invention refers to the reaction in which nitrate ions (NO3) produce ammonia under the action of an external electric field. - An electrochemical reduction reaction occurs at the cathode surface, converting the ions into ammonia (NH3) or ammonium ions (NH4). + The process involves the generation of NH3 in acidic or neutral electrolytes, which captures H+. + Transformed into NH4 + In an alkaline electrolyte, NH3 is generated.

[0032] Furthermore, the sulfur oxidation reaction (SOR) described in this invention refers to the reaction of sulfur ions (S) on the anode surface. 2- It is the process by which sulfur loses electrons under electrochemical oxidation and is mainly converted into elemental sulfur.

[0033] Furthermore, the methanol oxidation reaction (MOR) described in this invention refers to the process by which methanol (CH3OH) loses electrons under electrochemical oxidation on the anode surface and is mainly converted into formic acid (HCOOH).

[0034] This invention also provides a method for simultaneously treating wastewater containing sulfur ions and wastewater containing nitrates. The method, using the dual-function system, specifically includes the following steps: Wastewater containing sulfur ions is introduced into the anode chamber of the dual-function system, and wastewater containing nitrates is introduced into the cathode chamber of the dual-function system. Voltage is applied for electrolysis.

[0035] Furthermore, the sulfur ions (S) in the sulfur-containing wastewater 2- ) loses electrons under electrochemical oxidation and is converted into elemental sulfur; the nitrate ions (NO3) in the nitrate-containing wastewater - Under the action of electrochemical reduction reaction, it gains electrons and is converted into ammonia (NH3) or ammonium ions (NH4). + ).

[0036] This invention also provides a method for simultaneously treating methanol-containing wastewater and nitrate-containing wastewater, using the dual-function system to simultaneously treat sulfur-containing wastewater and methanol-containing wastewater, specifically including the following steps: Methanol-containing wastewater is introduced into the anode chamber of the dual-function system, and nitrate-containing wastewater is introduced into the cathode chamber of the dual-function system. Voltage is applied for electrolysis.

[0037] Furthermore, the methanol in the methanol-containing wastewater loses electrons under electrochemical oxidation and is converted into formic acid (HCOOH); the nitrate ions (NO3) in the nitrate-containing wastewater... - Under the action of electrochemical reduction reaction, it gains electrons and is converted into ammonia (NH3) or ammonium ions (NH4). + ).

[0038] The present invention has the following beneficial effects: This invention uses a copper-based current collector as a carrier, and obtains a surface-modified copper-based chalcogenide nanoarray material through a high-temperature gas-solid conversion reaction and subsequent calcination amorphous modification. On the one hand, this material is naturally rich in intrinsic Cu. + Catalytically active species, and the amorphous shell on the surface can stabilize Cu. + Active sites, Cu under negative potential suppression conditions + Electrons are captured and reduced to Cu 0 On the other hand, the amorphous surface layer can effectively regulate the electronic structure of copper-based chalcogenides, optimize the adsorption of nitrogen-containing intermediates, and thus promote the directional deoxygenation and hydrogenation of nitrogen-containing intermediates to generate NH3. Therefore, the above materials exhibit excellent ammonia production rate, high Faradaic efficiency, and good long-term operational stability in the electrocatalytic nitrate reduction to ammonia reaction. They can also be coupled with sulfur oxidation (or methanol oxidation), significantly reducing the energy consumption of wastewater resource recovery processes and demonstrating good environmental and economic benefits. Attached Figure Description

[0039] Figure 1 The images show X-ray diffraction (XRD) patterns of the surface-modified amorphous Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1, the crystalline Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 1, and the amorphous Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 2.

[0040] Figure 2 The images show X-ray diffraction (XRD) patterns of the surface-amorphously modified Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Example 2 and the crystalline Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Comparative Example 6.

[0041] Figure 3 The images show X-ray diffraction (XRD) patterns of the surface-amorphously modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 and the crystalline Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Comparative Example 7.

[0042] Figure 4This is a scanning electron microscope (SEM) image of the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1.

[0043] Figure 5 This is a scanning electron microscope (SEM) image of the surface amorphous modified Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Example 2.

[0044] Figure 6 This is a scanning electron microscope (SEM) image of the surface amorphous modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3.

[0045] Figure 7 The graph shows the linear sweep voltammetry (LSV) results of the electrocatalytic nitrate reduction to ammonia production (NO3RR) reaction of the following materials: Cu2S nanoarray material with amorphous surface modification loaded on the copper foam (CF) current collector obtained in Example 1; crystalline Cu2S nanoarray material with amorphous surface modification loaded on the copper foam (CF) current collector obtained in Comparative Example 1; amorphous Cu2S nanoarray material with amorphous surface modification loaded on the copper foam (CF) current collector obtained in Comparative Example 2; crystalline Cu3N nanoarray material with amorphous surface modification loaded on the copper foam (CF) current collector obtained in Comparative Example 3; Cu3N nanoarray material with amorphous surface modification loaded on the copper foam (CF) current collector obtained in Comparative Example 4; and Cu3P nanoarray material with amorphous surface modification loaded on the copper plate (CP) current collector obtained in Comparative Example 5.

[0046] Figure 8 The graph shows the stability test results for the electrocatalytic reduction of nitrate to ammonia (NO3RR). Figure 8 Figure A in the figure shows the stability test results of the surface amorphous modified Cu2S nanoarray material loaded on the foamed copper (CF) current collector obtained in Example 1. Figure 8 Figure B in the figure shows the stability test results of the crystalline Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 1.

[0047] Figure 9 This is a diagram of a bifunctional coupled system for electrocatalytic nitrate reduction to ammonia production (NO3RR) || sulfur oxidation (SOR) consisting of a surface-modified Cu2S nanoarray material supported on a copper foam (CF) current collector obtained in Example 1.

[0048] Figure 10The graph shows the linear sweep voltammetry (LSV) results of the electrocatalytic nitrate reduction to ammonia production (NO3RR) || sulfur oxidation (SOR) bifunctional coupled system composed of the surface amorphous modified Cu2S nanoarray material loaded on the foamed copper (CF) current collector obtained in Example 1 and the crystalline Cu2S nanoarray material loaded on the foamed copper (CF) current collector obtained in Comparative Example 1.

[0049] Figure 11 The figure shows the stability test results of the electrocatalytic nitrate reduction to ammonia production (NO3RR) || sulfur oxidation (SOR) bifunctional coupled system composed of a surface-amorphously modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1.

[0050] Figure 12 The graph shows the linear sweep voltammetry (LSV) results of the electrocatalytic nitrate reduction to ammonia production (NO3RR) reaction of the surface amorphous modified Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Example 2 and the crystalline Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Comparative Example 6.

[0051] Figure 13 The graph shows the linear sweep voltammetry (LSV) results of the electrocatalytic nitrate reduction to ammonia production (NO3RR) reaction of the surface amorphous modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 and the crystalline Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Comparative Example 7.

[0052] Figure 14 This is a diagram of a bifunctional coupled system for electrocatalytic nitrate reduction to ammonia production (NO3RR) and methanol oxidation (MOR) consisting of a surface-modified Cu2Se nanoarray material loaded on a copper mesh (CW) current collector obtained in Example 3.

[0053] Figure 15 The graph shows the linear sweep voltammetry (LSV) results of the bifunctional coupled system for electrocatalytic nitrate reduction to ammonia production (NO3RR) and methanol oxidation (MOR) reactions, consisting of a surface-modified Cu2Se nanoarray material loaded on a copper mesh (CW) current collector obtained in Example 3.

[0054] Figure 16 The figure shows the stability test results of the electrocatalytic nitrate reduction to ammonia production (NO3RR) || methanol oxidation (MOR) bifunctional coupling system composed of a surface amorphous modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3. Detailed Implementation

[0055] 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.

[0056] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0057] Example 1: Amorphous Cu2S nanoarray material with surface modification loaded on a copper foam (CF) current collector The surface-modified Cu2S nanoarray material loaded on the copper foam (CF) current collector is prepared by the following steps: (1) Three 2×3 cm pretreated copper foam (CF) sheets were used as current collectors and mixed with sulfur powder (gas-solid conversion source material, sulfur source) at a mass ratio of 1:50. The mixture was placed in a gas atmosphere with a volume ratio of 5:95 of hydrogen (H2) and nitrogen (N2) at a gas flow rate of 30 mL / min. The temperature was increased to 600 °C at a heating rate of 8 °C / min and carried out a high-temperature gas-solid conversion reaction for 6 h. After the reaction was completed, the mixture was naturally cooled to room temperature (25 °C) to obtain crystalline Cu2S nanoarray material loaded on the CF current collector. (2) The crystalline Cu2S nanoarray material loaded on the CF current collector obtained in step (1) is placed in a muffle furnace and heated to 350 °C at 4 °C / min in an air atmosphere and calcined for 3 h to obtain the surface amorphous modified Cu2S nanoarray material loaded on the CF current collector.

[0058] Example 2: Amorphous Cu2Te nanoarray material loaded on a copper plate (CP) current collector. The surface-modified Cu2Te nanoarray material loaded on the copper plate (CP) current collector is prepared by the following steps: (1) Two 2×4 cm pretreated copper plates (CP) were used as current collectors and mixed with tellurium powder (gas-solid conversion source material, tellurium source) at a mass ratio of 1:20. The mixture was placed in a gas atmosphere with a volume ratio of hydrogen (H2) and argon (Ar) of 5:95. The gas flow rate was 5 mL / min. The temperature was increased to 500 °C at a heating rate of 4 °C / min and carried out a high-temperature gas-solid conversion reaction for 8 h. After the reaction was completed, the mixture was naturally cooled to room temperature (25 °C) to obtain crystalline Cu2Te nanoarray material loaded on the CP current collector. (2) The crystalline Cu2Te nanoarray material loaded on the CP current collector obtained in step (1) is placed in a muffle furnace and heated to 250 °C at 2 °C / min in an air atmosphere and calcined for 4 h to obtain the surface amorphous modified Cu2Te nanoarray material loaded on the CP current collector.

[0059] Example 3: Amorphously Modified Cu₂Se Nanoarray Material Loaded on a Copper Mesh (CW) Current Collector The surface-modified Cu2Se nanoarray material loaded on a copper mesh (CW) current collector is prepared by the following steps: (1) A 2×4 cm pretreated copper mesh (CW) was ultrasonically cleaned in 2 M hydrochloric acid, anhydrous ethanol and deionized water for 10 min in turn. It was mixed with selenium powder (gas-solid conversion source material, selenium source) at a mass ratio of 1:10 and placed in a gas atmosphere with a volume ratio of hydrogen (H2) and helium (He) of 5:95. The gas flow rate was 10 mL / min, and the temperature was raised to 700 ℃ at a heating rate of 10 ℃ / min. The high-temperature gas-solid conversion reaction was carried out for 4 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain crystalline Cu2Se nanoarray material loaded on CW current collector. (2) The crystalline Cu2Se nanoarray material loaded on the CW current collector obtained in step (1) is placed in a muffle furnace and heated to 450 °C at 6 °C / min in an air atmosphere and calcined for 2 h to obtain the surface amorphous modified Cu2Se nanoarray material loaded on the CW current collector.

[0060] Example 4: Amorphously Modified Cu2S Nanoarray Material Loaded on a Copper Foam (CF) Current Collector The difference from Example 1 is that the calcination time in step (2) is 2 h, while the other steps and conditions remain unchanged, resulting in a surface amorphous modified Cu2S nanoarray material loaded on a copper foam (CF) current collector.

[0061] Example 5: Amorphously Modified Cu2S Nanoarray Material Loaded on a Copper Foam (CF) Current Collector The difference from Example 1 is that the calcination time in step (2) is 4 h, while the other steps and conditions remain unchanged, resulting in a surface amorphous modified Cu2S nanoarray material loaded on a copper foam (CF) current collector.

[0062] Example 6: Amorphously modified Cu2Te nanoarray material loaded on a copper plate (CP) current collector The difference from Example 2 is that the calcination time in step (2) is 2 h, while the other steps and conditions remain unchanged, resulting in a surface amorphous modified Cu2Te nanoarray material loaded on a copper plate (CP) current collector.

[0063] Example 7: Amorphously Modified Cu2Se Nanoarray Material Loaded on a Copper Mesh (CW) Current Collector The difference from Example 3 is that the calcination time in step (2) is 4 h, while the other steps and conditions remain unchanged, resulting in a surface amorphous modified Cu2Se nanoarray material loaded on a copper mesh (CW) current collector.

[0064] Comparative Example 1: Crystalline Cu2S nanoarray material supported on copper foam (CF) current collector The difference from Example 1 is that no calcination was performed. The crystalline Cu2S nanoarray material loaded on the copper foam (CF) current collector was prepared by the following steps: Three 2×3 cm pretreated copper foam (CF) sheets were used as current collectors and mixed with sulfur powder (the gas-solid conversion source material, sulfur source) at a mass ratio of 1:50. The mixture was placed in a gas atmosphere with a hydrogen (H2) to nitrogen (N2) volume ratio of 5:95 and a gas flow rate of 30 mL / min. The temperature was increased to 600 °C at a rate of 8 °C / min for a high-temperature gas-solid conversion reaction for 6 h. After the reaction was completed, the mixture was naturally cooled to room temperature (25 °C) to obtain crystalline Cu2S nanoarray material loaded on the CF current collector.

[0065] Comparative Example 2: Amorphous Cu2S nanoarray material loaded on a copper foam (CF) current collector The difference from Example 1 is that the calcination time is extended to 8 hours, so that the crystalline Cu2S nanoarray material loaded on the copper foam (CF) current collector is completely transformed into amorphous Cu2S nanoarray material. The amorphous Cu2S nanoarray material loaded on the copper foam (CF) current collector is prepared by the following steps: (1) Three 2×3 cm pretreated copper foam (CF) sheets were used as current collectors and mixed with sulfur powder (gas-solid conversion source material, sulfur source) at a mass ratio of 1:50. The mixture was placed in a gas atmosphere with a volume ratio of 5:95 of hydrogen (H2) and nitrogen (N2) at a gas flow rate of 30 mL / min. The temperature was increased to 600 °C at a heating rate of 8 °C / min and carried out a high-temperature gas-solid conversion reaction for 6 h. After the reaction was completed, the mixture was naturally cooled to room temperature (25 °C) to obtain crystalline Cu2S nanoarray material loaded on the CF current collector.

[0066] (2) The crystalline Cu2S nanoarray material loaded on the CF current collector obtained in step (1) is placed in a muffle furnace and heated to 350 °C at 4 °C / min in an air atmosphere and calcined for 8 h to obtain the amorphous Cu2S nanoarray material loaded on the CF current collector. Comparative Example 3: Crystalline Cu3N nanoarray material supported on copper foam (CF) current collector The crystalline Cu3N nanoarray material loaded on the copper foam (CF) current collector is prepared by the following steps: (1) Dissolve 10.3 g (250 mmol) sodium hydroxide (NaOH) and 10.20 g (60 mmol) hydrogen peroxide (H2O2, 30%wt) in 60 mL of isopropanol and stir thoroughly on a stirrer for 1 h (stirrer speed is 450 rpm) to obtain a homogeneous mixed solution. Then, immerse two 1×3 cm pretreated (ultrasonically cleaned in 2 M hydrochloric acid, anhydrous ethanol and deionized water for 10 min respectively) copper foam (CF) in the solution and perform an oxidative etching reaction at 50 °C for 24 h. After the reaction is completed, allow it to cool naturally to room temperature (25 °C). The cooled material is washed three times with isopropanol and ultrapure water respectively, and then dried in a forced-air drying oven at 60 °C for 24 h to obtain Cu(OH)2 nanoarray precursor loaded on CF current collector. (2) The Cu(OH)2 nanoarray material loaded on the CF current collector obtained in step (1) is mixed with urea (gas-solid conversion source material, nitrogen source) at a mass ratio of 1:5, placed in a nitrogen (N2) atmosphere, with a nitrogen flow rate of 2 mL / min, and heated to 200 ℃ at a heating rate of 2 ℃ / min for 8 h of high-temperature gas-solid conversion reaction. After the reaction is completed, it is naturally cooled to room temperature to obtain crystalline Cu3N nanoarray material loaded on the CF current collector.

[0067] Comparative Example 4: Amorphous Cu3N nanoarray material with surface modification loaded on copper foam (CF) current collector A surface-modified Cu3N nanoarray material supported on a copper foam (CF) current collector is prepared by the following steps: (1) Dissolve 10.3 g (250 mmol) sodium hydroxide (NaOH) and 10.20 g (60 mmol) hydrogen peroxide (H2O2, 30%wt) in 60 mL of isopropanol and stir thoroughly on a stirrer for 1 h (stirrer speed is 450 rpm) to obtain a homogeneous mixed solution. Then, immerse two 1×3 cm pretreated copper foam (CF) sheets (which were ultrasonically cleaned in 2 M hydrochloric acid, anhydrous ethanol and deionized water for 10 min respectively) in the solution and perform an oxidation etching reaction at 50 °C for 24 h. After the reaction is completed, allow it to cool naturally to room temperature (25 °C). The cooled material is washed three times with isopropanol and ultrapure water respectively and dried in a forced-air drying oven at 60 °C for 24 h to obtain Cu(OH)2 nanoarray precursor loaded on CF current collector.

[0068] (2) The Cu(OH)2 nanoarray material loaded on the CF current collector obtained in step (1) was mixed with urea (gas-solid conversion source material, nitrogen source) at a mass ratio of 1:5, placed in a nitrogen (N2) atmosphere, with a nitrogen flow rate of 2 mL / min, and heated to 200 ℃ at a heating rate of 2 ℃ / min for a high-temperature gas-solid conversion reaction for 8 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain the crystalline Cu3N nanoarray material loaded on the CF current collector.

[0069] (3) The crystalline Cu3N nanoarray material loaded on the CF current collector obtained in step (2) is placed in a muffle furnace and heated to 350 °C at 4 °C / min in an air atmosphere and calcined for 3 h to obtain the surface amorphous modified Cu3N nanoarray material loaded on the CF current collector.

[0070] Comparative Example 5: Amorphously modified Cu3P nanoarray material loaded on a copper plate (CP) current collector. The surface-modified Cu3P nanoarray material loaded on the copper plate (CP) current collector is prepared by the following steps: (1) Three 2×3 cm pretreated copper plates (CP) were ultrasonically cleaned in 2 M hydrochloric acid, anhydrous ethanol and deionized water for 10 min respectively. They were mixed with red phosphorus (gas-solid conversion source material, phosphorus source) at a mass ratio of 1:50 and placed in a gas atmosphere with a volume ratio of hydrogen (H2) and nitrogen (N2) of 5:95. The gas flow rate was 30 mL / min, and the temperature was raised to 700 ℃ at a heating rate of 8 ℃ / min for 4 h. After the reaction was completed, the temperature was naturally cooled to room temperature (25 ℃) to obtain crystalline Cu3P nanoarray material loaded on CP current collector.

[0071] (2) The crystalline Cu3P nanoarray material loaded on the CP current collector obtained in step (1) is placed in a muffle furnace and heated to 300 ℃ at 2 ℃ / min in an air atmosphere and calcined for 2 h to obtain the surface amorphous modified Cu3P nanoarray material loaded on the CP current collector.

[0072] Comparative Example 6: Crystalline Cu₂Te nanoarray material loaded on a copper plate (CP) current collector The difference from Example 2 is that no calcination was performed. The crystalline Cu2Te nanoarray material loaded on the copper plate (CP) current collector was prepared by the following steps: Two 2×4 cm pretreated copper plates (CP) were ultrasonically cleaned in 2 M hydrochloric acid, anhydrous ethanol, and deionized water for 10 min each, respectively. They were then mixed with tellurium powder (the gas-solid conversion source material, tellurium source) at a mass ratio of 1:20. The mixture was placed in a gas atmosphere with a hydrogen (H2) to argon (Ar) volume ratio of 5:95 and a gas flow rate of 5 mL / min. The temperature was increased to 500 °C at a heating rate of 4 °C / min for 8 h. After the reaction, the mixture was naturally cooled to room temperature (25 °C) to obtain crystalline Cu2Te nanoarray material loaded on the CP current collector.

[0073] Comparative Example 7: Crystalline Cu₂Se nanoarray material loaded on a copper mesh (CW) current collector The difference from Example 3 is that no calcination was performed. The crystalline Cu2Se nanoarray material loaded on the copper mesh (CW) current collector was prepared by the following steps: A 2×4 cm pretreated copper mesh (CW) was ultrasonically cleaned in 2 M hydrochloric acid, anhydrous ethanol, and deionized water for 10 min each. It was then mixed with selenium powder (the source material for gas-solid conversion, selenium source) at a mass ratio of 1:10. The mixture was placed in a gas atmosphere with a hydrogen (H2) to helium (He) volume ratio of 5:95 and a gas flow rate of 10 mL / min. The temperature was increased to 700 °C at a heating rate of 10 °C / min for 4 h for high-temperature gas-solid conversion reaction. After the reaction, the mixture was naturally cooled to room temperature (25 °C) to obtain crystalline Cu2Se nanoarray material loaded on the CW current collector.

[0074] Test Example 1: Material Characterization The phase structure and properties of the nanoarray materials obtained in Example 4 and Example 5 are basically the same as those of the nanoarray materials obtained in Example 1. The phase structure and properties of the nanoarray materials obtained in Example 6 are basically the same as those of the nanoarray materials obtained in Example 2. The phase structure and properties of the nanoarray materials obtained in Example 7 are basically the same as those of the nanoarray materials obtained in Example 3. Therefore, the following descriptions will only use Examples 1, 2, and 3 as representatives.

[0075] 1. X-ray diffraction (XRD) analysis X-ray diffraction (XRD) analysis was performed on the nanoarray materials obtained in Examples 1 to 3, and the nanoarray materials obtained in Comparative Examples 1, 2, 6 and 7.

[0076] The X-ray diffraction (XRD) analysis results of the nanoarray materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 are as follows: Figure 1 As shown. In the XRD pattern of the surface amorphous modified Cu2S nanoarray material loaded on the CF current collector obtained in Example 1, although the characteristic diffraction peaks of crystalline Cu2S belonging to standard card #PDF 026-1116 are clearly identifiable, their full width at half maximum (FWHM) increases and peak intensity decreases significantly, reflecting a significant decrease in crystal order. This change confirms the successful introduction of surface amorphous modification. In the XRD pattern of the crystalline Cu2S nanoarray material loaded on the CF current collector obtained in Comparative Example 1, its diffraction peaks are consistent with the characteristic sharp diffraction peaks of crystalline Cu2S in standard card #PDF 026-1116, indicating that it is a complete crystalline structure. In the XRD pattern of the amorphous Cu2S nanoarray material loaded on the CF current collector obtained in Comparative Example 2, it is shown that there is no periodic lattice arrangement in the sample, confirming that Cu2S in the obtained nanoarray material exists in an amorphous form.

[0077] The X-ray diffraction (XRD) analysis results of the nanoarray materials obtained in Example 2 and Comparative Example 6 are as follows: Figure 2 As shown. In the XRD pattern of the surface amorphous modified Cu2Te nanoarray material loaded on the CP current collector obtained in Example 2, although the characteristic diffraction peaks of crystalline Cu2Te belonging to standard card #PDF 039-1061 can be clearly identified, their full width at half maximum (FWHM) increases and their peak intensity decreases significantly, reflecting a significant decrease in crystal order. This change confirms the successful introduction of surface amorphous modification. In the XRD pattern of the crystalline Cu2Te nanoarray material loaded on the CP current collector obtained in Comparative Example 6, its diffraction peaks are consistent with the characteristic sharp diffraction peaks of crystalline Cu2Te in standard card #PDF 039-1061, indicating that it has a complete crystalline structure.

[0078] The X-ray diffraction (XRD) analysis results of the nanoarray materials obtained in Example 3 and Comparative Example 7 are as follows: Figure 3As shown. In the XRD pattern of the surface amorphous modified Cu2Se nanoarray material loaded on the CW current collector obtained in Example 3, although the characteristic diffraction peaks of crystalline Cu2Se belonging to standard card #PDF 004-0839 can be clearly identified, their full width at half maximum (FWHM) increases and their peak intensity decreases significantly, reflecting a significant decrease in crystal order. This change confirms the successful introduction of surface amorphous modification. In the XRD pattern of the crystalline Cu2Se nanoarray material loaded on the CW current collector obtained in Comparative Example 7, its diffraction peaks are consistent with the characteristic sharp diffraction peaks of crystalline Cu2Se in standard card #PDF 004-0839, indicating that it has a complete crystalline structure.

[0079] 2. Scanning electron microscopy (SEM) analysis The nanoarray materials obtained in Examples 1 to 3 were analyzed by scanning electron microscopy (SEM).

[0080] The results of the surface amorphous modified Cu2S nanoarray material loaded on the CF current collector obtained in Example 1 are as follows: Figure 4 As shown, the uniformly distributed nanoarray structure on the CF current collector is clearly visible.

[0081] The results of the surface amorphous modified Cu2Te nanoarray material loaded on the CP current collector obtained in Example 2 are as follows: Figure 5 As shown, the uniformly distributed nanoarray structure on the CP current collector is clearly visible.

[0082] The results of the surface-amorphously modified Cu2Se nanoarray material loaded on the CW current collector obtained in Example 3 are as follows: Figure 6 As shown, the uniformly distributed nanoarray structure on the CW current collector is clearly visible.

[0083] Application Example 1: Evaluation of the wastewater resource recovery performance of the electrocatalytic nitrate reduction to ammonia production reaction and the bifunctional coupling system. 1. Test conditions and parameters Electrochemical tests were performed using a Koster electrochemical workstation with a standard three-electrode system. The main indicators for evaluating the activity of the nanoarray materials prepared in the examples or comparative examples included the current (J) that can be excited at the same voltage or the voltage (E) required to reach the same current density, the ammonia generation rate, and the Faraday efficiency.

[0084] RHE in the following description stands for Reversible Hydrogen Electrode, and Hg / HgO stands for Mercury / Mercury Oxide Reference Electrode.

[0085] To eliminate variations in testing conditions and systematic errors, and to ensure that the measured electrocatalytic performance data accurately reflects the intrinsic activity of the materials, the solution resistance (Rs) values ​​of all materials were collected at open-circuit potential before each electrochemical data acquisition. Cyclic voltammetry (CV) curves were repeatedly scanned within the voltage range of -1.3 to 0 V vs. Hg / HgO until stable. Subsequently, linear sweep voltammetry (LSV) tests were performed within the voltage range of -1.3 to 0 V vs. Hg / HgO, and the LSV curves were compensated for with 80% solution resistance (IR). Simultaneously, according to formula E... （RHE） = E （Hg / HgO） + 0.098 + 0.05916 × pH, the potential value E （Hg / HgO Convert to E （RHE） ; Among them, E （RHE） V represents the potential relative to the reversible hydrogen electrode. E （Hg / HgO） V represents the measured potential relative to the mercury / mercury oxide reference electrode. 0.098 is the standard potential correction value for the Hg / HgO electrode at 25 °C in 1M KOH (deionized water as solvent); 0.05916 × pH represents the pH term in the Nernst equation.

[0086] 2. Performance testing of electrocatalytic nitrate reduction to ammonia production reaction (NO3RR) The electrocatalytic activity of the following materials in NO3RR performance was tested: the surface-modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1, the crystalline Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 1, the amorphous Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 2, the crystalline Cu3N nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 3, the surface-modified Cu3N nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 4, and the surface-modified Cu3P nanoarray material loaded on the copper plate (CP) current collector.

[0087] In addition, the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1 and the crystalline Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 1 were subjected to stability tests for electrocatalytic nitrate reduction to ammonia production.

[0088] (1) Experimental methods Electrocatalytic activity: using nanoarray materials prepared in the examples or comparative examples as the working electrode (1×1 cm⁻¹) 2), Platinum (Pt) sheet (1×1 cm) 2 In a three-electrode system with the counter electrode and the Hg / HgO electrode as the reference electrode, linear sweep voltammetry (LSV) was performed within the voltage range of -1.3 to 0 V vs. Hg / HgO to study its electrocatalytic performance. The electrolyte used was a mixed solution containing 0.1 M potassium nitrate and 1 M potassium hydroxide (deionized water as the solvent). When a current was applied to the above three-electrode system, the NO3RR reaction occurred at the working electrode. Under alkaline conditions, nitrate (NO3)... - It is reduced to NH3.

[0089] Ammonia formation rate and Faraday efficiency: The electrocatalytic performance of the nanoarray material for ammonia production by chronoamperometry (CA) was tested for 1 h at -0.4 V vs. RHE. The ammonia product was quantitatively analyzed by UV-Vis spectrophotometry. The specific operation procedure is as follows: After the CA test, 100 μL of the reaction solution was injected into 9.5 mL of deionized water for dilution. 200 μL of potassium sodium tartrate solution (500 g / L) was added to the above solution. Finally, 200 μL of Nessler's reagent was added. After standing at room temperature for 20 min to stabilize, the solution was placed in a UV spectrophotometer for UV-Vis testing. The characteristic peak was located at 420 nm, and the content of NH3 generated in the solution was measured.

[0090] The ammonia formation rate and Faraday efficiency are calculated using the following formula: Faraday efficiency = (8 × F × C) NH3 ×V) / (M NH3 ×Q); Ammonia formation rate = (C NH3 ×V) / (M NH3 ×t×A); Q = i × t; In the formula, F is the Faraday constant (96485 C / mol); C NH3 The mass concentration of NH3 in the aqueous solution (g / L); V represents the total volume of the electrolyte, in L; i is the current density, A / cm² 2 ; t is the electrolysis time, in hours; M NH3 Expresses the molar mass of NH3, in g / mol; Q represents the total charge passing through the electrode, C; A is the area of ​​the electrode, in cm² 2 .

[0091] (2) Experimental results Experimental results of electrocatalytic activity are as follows: Figure 7 As shown, for the electrocatalytic performance of the nitrate reduction to ammonia reaction (NO3RR), the order of electrocatalytic activity is Comparative Example 1 < Comparative Example 2 < Comparative Example 3 < Comparative Example 5 < Comparative Example 4 < Example 1. This indicates that the surface-modified Cu2S nanoarray material supported on the foamed copper (CF) current collector obtained in Example 1 has better electrocatalytic activity. Compared with surface-modified copper-based non-chalcogen compounds, surface-modified copper-based chalcogen compounds have better NO3RR performance.

[0092] Based on the UV-vis test results, the ammonia formation rate and Faraday efficiency are shown in Table 1.

[0093] Table 1. Ammonia formation rate and Faraday efficiency

[0094] As shown in Table 1, the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1 has a better ammonia production rate and higher selectivity.

[0095] The results of the stability test are as follows Figure 8 As shown, the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1 maintained a high ammonia generation rate and Faraday efficiency after 20 tests, while the crystalline Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 1 deactivated rapidly.

[0096] 3. Bifunctional Coupled System – Electrocatalytic Nitrate Reduction to Ammonia Production (NO3RR) || Sulfur Oxidation (SOR) System Performance Testing The electrocatalytic activity and stability of the bifunctional coupling system (NO3RR || SOR system) assembled from the surface-modified amorphous Cu2S nanoarray material supported on the copper foam (CF) current collector obtained in Example 1 and the crystalline Cu2S nanoarray material supported on the copper foam (CF) current collector obtained in Comparative Example 1 were tested. The bifunctional coupling system assembled from the surface-modified amorphous Cu2S nanoarray material supported on the copper foam (CF) current collector obtained in Example 1—the electrocatalytic nitrate reduction to ammonia production (NO3RR) || oxygen evolution reaction (OER) system (NO3RR || OER system)—was used as a control group to evaluate the energy-saving advantage of SOR replacing OER. The NO3RR || SOR system assembled from the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1 is named System A; the NO3RR || SOR system assembled from the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Comparative Example 1 is named System B; and the NO3RR || OER system assembled from the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1 is named System C.

[0097] (1) Experimental methods NO3RR || SOR system devices such as Figure 9 As shown: Amorphous Cu2S nanoarray material with a surface layer supported on a copper foam (CF) current collector obtained in Example 1, or crystalline Cu2S nanoarray material supported on a copper foam (CF) current collector obtained in Comparative Example 1, were used as the anode and cathode. SOR was coupled to the anode, and NO3RR was coupled to the cathode. The cathode electrolyte was a mixed solution containing 0.1 M potassium nitrate and 1 M potassium hydroxide (solvent: deionized water), and the anode electrolyte was a mixed solution of 1 M sodium sulfide and 1 M sodium hydroxide (solvent: deionized water). The electrolytes at both electrodes were continuously refreshed during operation to ensure stable reactant concentrations and timely product discharge. When current was applied to the NO3RR || SOR system, the NO3RR reaction occurred at the cathode. Under alkaline conditions, nitrate (NO3)... - The sulfur in the sulfide is reduced to NH3; SOR occurs at the anode, and the sulfur in the sulfide is reduced to NH3. 2- It is oxidized to elemental sulfur.

[0098] The NO3RR || OER system uses a surface-modified Cu2S nanoarray material loaded on a copper foam (CF) current collector obtained in Example 1 as the anode and cathode. OER is coupled to the anode, and NO3RR is coupled to the cathode. The cathode electrolyte is a mixed solution containing 0.1 M potassium nitrate and 1 M potassium hydroxide (solvent: deionized water), and the anode electrolyte is 1 M potassium hydroxide (solvent: deionized water). The electrolytes at both electrodes are continuously refreshed during operation to ensure stable reactant concentrations and timely product removal. When current is applied to the NO3RR || OER system, the NO3RR reaction occurs at the cathode. Under alkaline conditions, nitrate (NO3) ions... - It is reduced to NH3; OER and OH are generated at the anode. - It is oxidized to O2.

[0099] Before each electrochemical data acquisition, the solution resistance (Rs) values ​​of all materials were collected at open circuit potential. The CV curves were scanned multiple times within the voltage range of 0~2 V until stable. Then, LSV tests were performed within the voltage range of 0~2 V, and the stability of the dual-function coupled system was tested.

[0100] (2) Experimental results Electrocatalytic activity results are as follows Figure 10 As shown, the bifunctional coupled system (NO3RR || SOR system) assembled from the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1 achieves 100 mA / cm². 2 The voltage required to achieve the desired current density is significantly lower than that required for the bifunctional coupling system (NO3RR || SOR system) assembled from crystalline Cu2S nanoarray materials loaded on a copper foam (CF) current collector obtained in Comparative Example 1, and the bifunctional coupling system (NO3RR || OER system) assembled from a surface-modified Cu2S nanoarray materials loaded on a copper foam (CF) current collector obtained in Example 1. These results indicate that the surface-modified Cu2S nanoarray material loaded on a copper foam (CF) current collector obtained in Example 1 possesses both excellent NO3RR and SOR catalytic activities, and exhibits a significant energy-saving advantage in the NO3RR || SOR system.

[0101] Stability results are as follows Figure 11 As shown, the bifunctional coupling system assembled from the surface amorphous modified Cu2S nanoarray material loaded on the foamed copper (CF) current collector obtained in Example 1 can operate stably for at least 600 hours.

[0102] In summary, the surface amorphous modified Cu2S nanoarray material loaded on the copper foam (CF) current collector obtained in Example 1 has excellent NO3RR performance, exhibiting excellent electrocatalytic activity, selectivity, and stability. Furthermore, when used simultaneously as the cathode and anode of a bifunctional coupling system (NO3RR || SOR system), it can efficiently achieve ammonia production at the cathode and elemental sulfur production at the anode, realizing the dual-function wastewater resource recovery and utilization.

[0103] Application Example 2: Performance Testing of Electrocatalytic Nitrate Reduction to Ammonia Production The electrocatalytic activity of the NO3RR performance of the following materials was tested: the surface amorphous modified Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Example 2, and the crystalline Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Comparative Example 6.

[0104] In addition, a CA test was performed for 1 h at -0.3 V vs. RHE. After completion, the ammonia generation rate and Faraday efficiency were obtained by UV-vis test. The specific test and calculation process is the same as in Application Example 1.

[0105] Electrocatalytic activity results are as follows Figure 12 As shown, for the electrocatalytic performance of the nitrate reduction to ammonia reaction (NO3RR), the order of electrocatalytic activity is Comparative Example 6 < Example 2, indicating that the surface amorphous modified Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Example 2 has better electrocatalytic activity.

[0106] Based on the UV-vis test results, the ammonia generation rate and Faraday efficiency are shown in Table 2.

[0107] Table 2. Ammonia formation rate and Faraday efficiency

[0108] As shown in Table 2, the surface amorphous modified Cu2Te nanoarray material loaded on the copper plate (CP) current collector obtained in Example 2 has a better ammonia production rate and higher selectivity.

[0109] Application Example 3: Study on the bifunctional wastewater resource recovery performance of electrocatalytic nitrate reduction to ammonia production and coupled anode methanol oxidation reaction. 1. Performance testing of electrocatalytic nitrate reduction to ammonia production reaction (NO3RR) The electrocatalytic activity of the following materials in NO3RR performance was tested: the surface amorphous modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3, and the crystalline Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Comparative Example 7.

[0110] In addition, a CA test was performed for 1 h at -0.35 V vs. RHE. After completion, the ammonia generation rate and Faraday efficiency were obtained by UV-vis test. The specific test and calculation process is the same as in Application Example 1.

[0111] The results of electrocatalytic activity are as follows Figure 13 As shown, for the electrocatalytic performance of nitrate reduction to ammonia production, the order of electrocatalytic activity is Comparative Example 7 < Example 3. The surface amorphous modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 has better electrocatalytic activity.

[0112] Based on the UV-vis test results, the ammonia generation rate and Faraday efficiency are shown in Table 3.

[0113] Table 3. Ammonia formation rate and Faraday efficiency

[0114] As shown in Table 3, the surface amorphous modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 has a better ammonia production rate and higher selectivity.

[0115] 2. Bifunctional Coupled System – Electrocatalytic Nitrate Reduction to Ammonia (NO3RR) || Performance Testing of Methanol Oxidation (MOR) System The electrocatalytic activity and stability of the bifunctional coupling system (NO3RR || MOR system) assembled from the surface-modified amorphous Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 and the crystalline Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Comparative Example 7 were tested. The bifunctional coupling system assembled from the surface-modified amorphous Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3—the electrocatalytic nitrate reduction to ammonia production (NO3RR) || oxygen evolution reaction (OER) system (NO3RR || OER system)—was used as a control group to evaluate the energy-saving advantage of MOR replacing OER. The NO3RR || MOR system assembled from the surface-modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 is named System D; the NO3RR || MOR system assembled from the surface-modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Comparative Example 7 is named System E; and the NO3RR || OER system assembled from the surface-modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 is named System F.

[0116] (1) Experimental methods NO3RR || MOR system devices such as Figure 14 As shown: Amorphous Cu2Se nanoarray material with a surface layer modified on a copper mesh (CW) current collector obtained in Example 3 or crystalline Cu2Se nanoarray material with a copper mesh (CW) current collector obtained in Comparative Example 7 were used as the anode and cathode, respectively. MOR was coupled to the anode, and NO3RR was coupled to the cathode. The cathode electrolyte was a mixed solution containing 0.1 M potassium nitrate and 1 M potassium hydroxide (solvent: deionized water), and the anode electrolyte was a mixed solution of 1 M methanol and 1 M potassium hydroxide (solvent: deionized water). The electrolytes at both electrodes were continuously refreshed during operation to ensure stable reactant concentrations and timely product discharge. When current was applied to the NO3RR || MOR system, the NO3RR reaction occurred at the cathode. Under alkaline conditions, nitrate (NO3)... - Methanol is reduced to NH3; at the anode, MOR occurs, and methanol is oxidized to formic acid (HCOOH).

[0117] NO3RR || OER System: Amorphous modified Cu2Se nanoarray material loaded on a copper mesh (CW) current collector obtained in Example 3 was used as the anode and cathode. OER was coupled to the anode, and NO3RR was coupled to the cathode. The cathode electrolyte was a mixed solution containing 0.1 M potassium nitrate and 1 M potassium hydroxide (solvent: deionized water), and the anode electrolyte was 1 M potassium hydroxide (solvent: deionized water). The electrolytes at both electrodes were continuously replenished during operation to ensure stable reactant concentrations and timely product removal. The specific testing procedure is described in Application Example 1.

[0118] Electrocatalytic activity results are as follows Figure 15 As shown, the bifunctional coupled system (NO3RR || MOR system) assembled from the copper mesh (CW) current collector loaded with amorphously modified Cu2Se nanoarray material on the surface, obtained in Example 3, achieves 100 mA / cm². 2 The voltage required to achieve the desired current density is significantly lower than that of the bifunctional coupling system (NO3RR || MOR system) assembled from crystalline Cu2Se nanoarray material loaded on a copper mesh (CW) current collector obtained in Comparative Example 7, and the bifunctional coupling system (NO3RR || OER system) assembled from surface-modified Cu2Se nanoarray material loaded on a copper mesh (CW) current collector obtained in Example 3. These results indicate that the surface-modified Cu2Se nanoarray material obtained in Example 3 possesses both excellent NO3RR and MOR catalytic activities, and exhibits a significant energy-saving advantage in the NO3RR || MOR system.

[0119] Stability test results are as followsFigure 16 As shown, the surface amorphous modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 can stably operate for at least 480 hours as a NO3RR || MOR system built with anode and cathode.

[0120] In summary, the surface amorphous modified Cu2Se nanoarray material loaded on the copper mesh (CW) current collector obtained in Example 3 has excellent NO3RR performance, exhibiting excellent electrocatalytic activity, selectivity, and stability. Furthermore, when used simultaneously as the cathode and anode of a bifunctional coupling system (NO3RR || MOR system), it can efficiently achieve ammonia production at the cathode and formic acid production at the anode, realizing the bifunctional recycling of wastewater resources.

[0121] 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 dual-function system, characterized in that, The dual-function system includes a power source, a diaphragm, a cathode, an anode, a cathode chamber, and an anode chamber. Both the anode and cathode are made of a surface-layer amorphous modified copper-based chalcogenide nanoarray material. This surface-layer amorphous modified copper-based chalcogenide nanoarray material is prepared using the following steps: S1: Mix the copper-based current collector with the gas-solid conversion source material, place it in a reducing gas atmosphere, and carry out a high-temperature gas-solid conversion reaction at 500~700 ℃ to obtain a crystalline copper-based chalcogenide nanoarray material loaded on the copper-based current collector. S2: The crystalline copper-based chalcogenide nanoarray material loaded on the copper-based current collector obtained in step S1 is placed in an air atmosphere and calcined for 2-4 hours until its surface part is transformed into an amorphous state, thereby obtaining the surface amorphous modified copper-based chalcogenide nanoarray material. The gas-solid conversion source material is sulfur powder, selenium powder, or tellurium powder; The mass ratio of the copper-based current collector to the gas-solid conversion source material is 1:(10~50). In step S2, the calcination satisfies the following conditions: (1) When the gas-solid conversion source material is sulfur powder, the copper-based chalcogenide is Cu2S, and the calcination temperature is 340~360 ℃; (2) When the gas-solid conversion source material is selenium powder, the copper-based chalcogenide is Cu2Se, and the calcination temperature is 440~460 ℃; (3) When the gas-solid conversion source material is tellurium powder, the copper-based chalcogenide is Cu2Te, and the calcination temperature is 240~260 °C; The reducing gas atmosphere contains hydrogen. The copper-based current collector is selected from at least one of copper foam, copper mesh, copper plate, and copper sheet.

2. The dual-function system as described in claim 1, characterized in that, The heating rate during calcination is 2~6 ℃ / min.

3. The application of the bifunctional system according to any one of claims 1 to 2 in the electrocatalytic reduction of nitrate to ammonia and oxidation reactions, characterized in that, The oxidation reaction is either a sulfur oxidation reaction or a methanol oxidation reaction.

4. The application as described in claim 3, characterized in that, The oxidation reaction is subject to the following conditions: (1) When the oxidation reaction is a sulfur oxidation reaction, the oxidation reaction is to convert sulfur ions into elemental sulfur; (2) When the oxidation reaction is a methanol oxidation reaction, the oxidation reaction is to convert methanol into formic acid.

5. A method for simultaneously treating wastewater containing sulfur ions and wastewater containing nitrates, characterized in that, The dual-function system according to any one of claims 1 to 2, which simultaneously treats wastewater containing sulfur ions and wastewater containing nitrates, specifically includes the following steps: Wastewater containing sulfur ions is introduced into the anode chamber of the dual-function system according to any one of claims 1 to 2, and wastewater containing nitrates is introduced into the cathode chamber of the dual-function system according to any one of claims 1 to 2, and a voltage is applied for electrolysis.

6. A method for simultaneously treating methanol-containing wastewater and nitrate-containing wastewater, characterized in that, The dual-function system according to any one of claims 1 to 2 for simultaneously treating methanol-containing wastewater and nitrate-containing wastewater specifically includes the following steps: Methanol-containing wastewater is introduced into the anode chamber of the dual-function system according to any one of claims 1 to 2, and nitrate-containing wastewater is introduced into the cathode chamber of the dual-function system according to any one of claims 1 to 2, and an applied voltage is used for electrolysis.

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