A surface-modified copper-based compound nanoarray electrode material and its application in electrocatalytic wastewater resource recovery.

Abstract

This invention belongs to the field of wastewater treatment technology, specifically relating to a surface-modified copper-based compound nanoarray electrode material and its electrocatalytic application in wastewater resource recovery. This invention uses phosphate compounds such as sodium tripolyphosphate, lithium ethylenediaminetetramethylenephosphonate, tetrasodium aminotrimethylenephosphonate, tetrapotassium pentaerythritol tetraphosphate, and tributyl phosphate to surface-modify the copper-based compound nanoarray electrode material. The resulting nanoarray electrode material exhibits excellent electrocatalytic activity and stability in electrocatalytic nitrate reduction coupled with sulfur oxidation or methanol oxidation reactions. In electrocatalytic devices, it can effectively reduce overall energy consumption, achieving energy saving and efficiency improvement in the wastewater resource recovery process, thus possessing both environmental benefits and economic value.

Description

Technical Field

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

[0002] Electrocatalytic nitrate reduction to ammonia (NO3RR) is driven by renewable electrical energy and can achieve highly efficient nitrate conversion under normal temperature and pressure conditions without the need for external high temperature, high pressure, or chemical reducing agents. It can selectively reduce nitrate ions in wastewater to ammonia (NH3, which is NH4 in water). + While simultaneously treating wastewater and recovering nitrogen resources, NO3RR has become a research hotspot in the intersection of water treatment and electrocatalysis. However, the NO3RR process is usually limited by the slow kinetics and high overpotential of the anodic oxygen evolution reaction (OER), resulting in high overall energy consumption and limiting its large-scale application. Therefore, in recent years, there has been a growing interest in coupling NO3RR with anodic sulfur oxidation (SOR) or methanol oxidation (MOR) reactions to reduce overall electrolysis energy consumption.

[0003] Among them, copper-based materials are among the most promising non-precious metal catalytic materials in the NO3RR field due to their high matching degree between the d-orbital energy level and the nitrate ion orbital, abundant raw material reserves, and low cost. However, under negative potential operating conditions, the active sites Cu in copper-based materials... + It is easily reduced to metallic Cu. 0 This leads to a rapid decline in catalytic activity and insufficient long-term stability; simultaneously, this type of material has a weak ability to promote water dissociation to generate active hydrogen (*H), resulting in the reaction intermediate nitrite (NO2) being produced. - It is difficult to achieve timely and deep hydrogenation conversion, ultimately resulting in low selectivity for ammonia. More importantly, in electrocatalytic devices, both the anode and cathode need to operate stably at specific potentials for a long time, which places higher demands on the bifunctional catalytic activity and durability of the electrode materials.

[0004] 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 simultaneous and efficient catalysis at the anode and cathode, is of great significance for promoting the deep treatment and resource utilization of wastewater and improving the current water environment quality. Summary of the Invention

[0005] This invention addresses the problem of the lack of copper-based electrocatalytic materials in the prior art that possess both high efficiency in reduction and oxidation catalytic activity, excellent long-term stability, and low energy consumption. The aim is to provide a surface-modified copper-based compound nanoarray electrode material.

[0006] A second objective of this invention is to provide an electrocatalytic device.

[0007] A third objective of this invention is to provide an application of the surface-modified copper-based compound nanoarray electrode material in electrocatalytic nitrate reduction to ammonia production and / or oxidation reactions.

[0008] A fourth objective of this invention is to provide the application of the electrocatalytic device in electrocatalytic nitrate reduction to ammonia production and / or oxidation reactions.

[0009] The fifth objective of this invention is to provide a method for treating wastewater.

[0010] The above-mentioned objective of this invention is achieved through the following technical solution: This invention provides a surface-modified copper-based compound nanoarray electrode material, which is prepared by the following steps: S1: The copper-based current collector is immersed in a solution containing a precipitant and an oxidant to carry out an oxidative etching reaction, thereby obtaining a copper hydroxide nanoarray precursor grown in situ on the copper-based current collector; S2: The copper hydroxide nanoarray precursor grown in situ on the copper-based current collector obtained in step S1 is mixed with the gas-solid reaction source material and placed in a reducing gas atmosphere. A high-temperature gas-solid conversion reaction is carried out at 500~800 ℃ to obtain copper-based compound nanoarray material loaded on the copper-based current collector. S3: The copper-based compound nanoarray material loaded on the copper-based current collector obtained in step S2 is immersed in a solution containing phosphoric acid compounds and left to stand for surface modification. After post-treatment, the surface-modified copper-based compound nanoarray electrode material is obtained. The gas-solid reaction source material is selected from at least one of sodium hypophosphite, thiourea, selenium powder, and tellurium powder. The mass ratio of the copper hydroxide nanoarray precursor to the gas-solid reaction source material is 1:(10~100). The phosphate compound is selected from at least one of sodium tripolyphosphate, lithium ethylenediaminetetramethylenephosphonate, tetrasodium aminotrimethylenephosphonate, tetrapotassium pentaerythritol tetraphosphate, and tributyl phosphate.

[0011] Furthermore, the phosphoric acid compound is a compound containing phosphate (-PO4) or phosphonate (-PO3H2).

[0012] Preferably, the precipitant is selected from at least one of potassium hydroxide, sodium hydroxide, sodium bicarbonate, and sodium oxalate.

[0013] Preferably, the oxidant is selected from at least one of ammonium persulfate, hydrogen peroxide, potassium persulfate, sodium persulfate, and hypochlorite.

[0014] Preferably, the solvent of the solution containing the precipitant and the oxidant is selected from water and / or alcohol compounds.

[0015] More preferably, the alcohol compound is selected from at least one of ethylene glycol, methanol, and ethanol.

[0016] Preferably, the molar volume ratio of the precipitant to the solvent is (180~560) mmol:100 mL, more preferably (187~556) mmol:100 mL.

[0017] Preferably, the molar volume ratio of the oxidant to the solvent of the solution containing the precipitant and the oxidant is (9~150) mmol:100 mL, more preferably (9~134) mmol:100 mL.

[0018] Preferably, the temperature of the oxidation etching reaction is 30~80 °C.

[0019] Preferably, the oxidation etching reaction takes 4 to 24 hours.

[0020] Preferably, in step S1, the post-processing includes washing and drying.

[0021] More preferably, in step S1, the washing involves washing with an alcohol compound and water sequentially, specifically washing with an alcohol compound 2 to 4 times and then washing with water 2 to 4 times.

[0022] More preferably, in step S1, the alcohol compound is selected from at least one of ethylene glycol, ethanol, and methanol.

[0023] More preferably, in step S1, the drying is performed at 40~80 °C for 6~24 h.

[0024] Preferably, the copper-based current collector is selected from copper mesh, copper plate, or copper foam.

[0025] More preferably, the copper-based current collector is pretreated.

[0026] More preferably, the pretreatment is ultrasonic cleaning, specifically, ultrasonic cleaning in 2 M hydrochloric acid, anhydrous ethanol, and deionized water for 10 min each.

[0027] Preferably, the reducing gas atmosphere contains hydrogen.

[0028] More preferably, the reducing gas atmosphere also contains a protective gas.

[0029] More preferably, the protective gas is selected from at least one of argon, helium, and nitrogen.

[0030] More preferably, the volume ratio of the hydrogen to the protective gas is (3~8):95.

[0031] Preferably, the gas flow rate of the reducing gas atmosphere is 10~50 mL / min.

[0032] Preferably, the high-temperature gas-solid conversion reaction takes 8 to 24 hours.

[0033] Preferably, the heating rate of the high-temperature gas-solid conversion reaction is 4~22 °C / min.

[0034] Preferably, the concentration of the solution containing the phosphoric acid compound is 0.9 w / v% to 20 w / v.

[0035] Preferably, the surface modification temperature is 25~60 ℃.

[0036] Preferably, the surface modification time is 2 to 18 hours.

[0037] Preferably, in step S3, the post-processing includes washing and drying.

[0038] More preferably, in step S3, the washing involves washing with water 2 to 4 times.

[0039] More preferably, in step S3, the drying is performed at 40~80 °C for 8~16 h.

[0040] The present invention also provides an electrocatalytic device, the electrocatalytic device comprising a power source, a membrane, a cathode, an anode, a cathode chamber, and an anode chamber, wherein the materials of the anode and the cathode each comprise at least one of the surface-modified copper-based compound nanoarray electrode materials.

[0041] The present invention also provides the application of the surface-modified copper-based compound nanoarray electrode material in the electrocatalytic reduction of nitrate to ammonia and / or oxidation reaction, wherein the oxidation reaction is a sulfur oxidation reaction or a methanol oxidation reaction.

[0042] The present invention also provides the application of the electrocatalytic device in the electrocatalytic reduction of nitrate to ammonia and / or oxidation reaction, wherein the oxidation reaction is a sulfur oxidation reaction or a methanol oxidation reaction.

[0043] 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.

[0044] 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.

[0045] 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).

[0046] The present invention also provides a method for treating wastewater, wherein the electrocatalytic device is used to treat wastewater, the wastewater comprising anode wastewater and cathode wastewater, the anode wastewater being methanol-containing wastewater or sulfur-containing wastewater, and the cathode wastewater being nitrate-containing wastewater.

[0047] Furthermore, the methanol in the methanol-containing wastewater loses electrons under electrochemical oxidation and is converted into formic acid (HCOOH).

[0048] Furthermore, the sulfur ions (S) in the sulfur-containing wastewater 2- It loses electrons under electrochemical oxidation and is converted into elemental sulfur.

[0049] Preferably, the cathode chamber is circulated with nitrate-containing wastewater.

[0050] Furthermore, 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). + ).

[0051] The present invention has the following beneficial effects: This invention employs phosphoric acid compounds such as sodium tripolyphosphate, lithium ethylenediaminetetramethylenephosphonate, tetrasodium aminotrimethylenephosphonate, tetrapotassium pentaerythritol tetraphosphate, and tributyl phosphate to modify the surface of copper-based compound nanoarray electrode materials. This modification layer can, on the one hand, modify the Cu... + The active species are effectively stabilized, and their reduction to Cu under negative potential conditions is inhibited at the chemical level. 0On the other hand, the electrode / electrolyte interface double-layer structure can be tuned to promote the enrichment of free water at the interface and accelerate the water dissociation process to generate active hydrogen (*H), thereby providing a sufficient supply of active hydrogen for the deep deoxygenation and hydrogenation of nitrogen-containing intermediates and driving the reaction pathway towards NH3 production. Based on the above mechanism, the prepared electrode material exhibits a high ammonia production rate, excellent Faradaic efficiency, and good long-term operational stability in the electrocatalytic nitrate reduction reaction. Simultaneously, this material can be coupled with the anodic sulfur oxidation reaction or the methanol oxidation reaction, possessing both excellent electrocatalytic nitrate reduction ammonia production performance and sulfur oxidation / methanol oxidation performance. This effectively reduces overall energy consumption in the electrocatalytic device, achieving energy saving and efficiency improvement in the wastewater resource recovery process, thus combining environmental benefits and economic value. Attached Figure Description

[0052] Figure 1 This is a scanning electron microscope (SEM) image of the sodium tripolyphosphate-modified Cu3P nanoarray material loaded on the copper mesh (CW) obtained in Example 1.

[0053] Figure 2 This is a scanning electron microscope (SEM) image of the Cu2S nanoarray material modified with lithium ethylenediaminetetramethylenephosphonate loaded on the copper plate (CP) obtained in Example 2.

[0054] Figure 3 This is a scanning electron microscope (SEM) image of Cu2Se nanoarray material modified with tetrasodium aminotrimethylphosphonate loaded on copper foam (CF) obtained in Example 3.

[0055] Figure 4 This is a scanning electron microscope (SEM) image of the pentaerythritol tetraphosphate tetrapotassium modified Cu2Te nanoarray material loaded on the copper mesh (CW) obtained in Example 4.

[0056] Figure 5 Linear sweep voltammetry (LSV) plots of the electrocatalytic nitrate reduction to ammonia production (NO3RR) reaction of the Cu3P nanoarray material modified with sodium tripolyphosphate loaded on the copper mesh (CW) obtained in Example 1, the Cu3P nanoarray material modified with tributyl phosphate loaded on the copper mesh (CW) obtained in Example 5, the Cu3P nanoarray material loaded on the copper mesh (CW) obtained in Comparative Example 1, and the Cu3P array material modified with aluminum metaphosphate loaded on the copper mesh (CW) obtained in Comparative Example 2.

[0057] Figure 6 The graph shows the stability test results for the electrocatalytic reduction of nitrate to ammonia (NO3RR). Figure 6 Figure A in the figure shows the stability test results of the sodium tripolyphosphate modified Cu3P nanoarray material loaded on the copper mesh (CW) obtained in Example 1; Figure 6Figure B in the figure shows the stability test results of the Cu3P nanoarray material loaded on the copper mesh (CW) obtained in Comparative Example 1. Figure 6 Figure C in the figure shows the stability test results of the Cu3P array material modified with aluminum metaphosphate loaded on the copper mesh (CW) obtained in Comparative Example 2.

[0058] Figure 7 This is a physical image of the electrocatalytic device for the electrocatalytic reaction of nitrate reduction to ammonia production (NO3RR) and methanol oxidation (MOR) assembled from sodium tripolyphosphate-modified Cu3P nanoarray materials loaded on a copper mesh (CW) obtained in Example 1.

[0059] Figure 8 Linear sweep voltammetry (LSV) plots of electrocatalytic devices for nitrate reduction to ammonia production (NO3RR) and methanol oxidation (MOR) assembled from sodium tripolyphosphate-modified Cu3P nanoarray materials loaded on copper mesh (CW) obtained in Example 1 and Cu3P nanoarray materials loaded on copper mesh (CW) obtained in Comparative Example 1.

[0060] Figure 9 The figure shows the stability test results of the electrocatalytic device for the electrocatalytic reaction of nitrate reduction to ammonia (NO3RR) and methanol oxidation (MOR) assembled by loading sodium tripolyphosphate modified Cu3P nanoarray material on copper mesh (CW) obtained in Example 1.

[0061] Figure 10 Linear sweep voltammetry (LSV) plots of the electrocatalytic nitrate reduction to ammonia production (NO3RR) of the Cu2S nanoarray material modified with lithium ethylenediaminetetramethylenephosphonate loaded on the copper plate (CP) obtained in Example 2 and the Cu2S nanoarray material loaded on the copper plate (CP) obtained in Comparative Example 3.

[0062] Figure 11 Linear sweep voltammetry (LSV) plots of the electrocatalytic nitrate reduction to ammonia production (NO3RR) of Cu2Se nanoarray material modified with tetrasodium aminotrimethylphosphonate loaded on copper foam (CF) obtained in Example 3 and Cu2Se nanoarray material loaded on copper foam (CF) obtained in Comparative Example 4.

[0063] Figure 12 This is a physical image of the electrocatalytic device for the nitrate reduction to ammonia production (NO3RR) || sulfur oxidation (SOR) electrocatalytic reaction assembled from Cu2Se nanoarray material modified with tetrasodium aminotrimethylphosphonate supported on copper foam (CF) obtained in Example 3.

[0064] Figure 13Linear sweep voltammetry (LSV) plots of electrocatalytic nitrate reduction to ammonia production (NO3RR) || sulfur oxidation (SOR) electrocatalytic devices assembled from Cu2Se nanoarray material modified with tetrasodium aminotrimethylphosphonate supported on copper foam (CF) obtained in Example 3 and Cu2Se nanoarray material supported on copper foam (CF) obtained in Comparative Example 4.

[0065] Figure 14 The figure shows the stability test results of the electrocatalytic nitrate reduction to ammonia production (NO3RR) || sulfur oxidation (SOR) electrocatalytic device assembled from Cu2Se nanoarray material modified with tetrasodium aminotrimethylphosphonate supported on copper foam (CF) obtained in Example 3.

[0066] Figure 15 Linear sweep voltammetry (LSV) plots of the electrocatalytic nitrate reduction to ammonia production (NO3RR) of the Cu2Te nanoarray material modified with pentaerythritol tetraphosphate loaded on the copper mesh (CW) obtained in Example 4 and the Cu2Te nanoarray material loaded on the copper mesh (CW) obtained in Comparative Example 5. Detailed Implementation

[0067] 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.

[0068] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0069] Example 1: Cu3P nanoarray material modified with sodium tripolyphosphate loaded on copper mesh The preparation method of the sodium tripolyphosphate modified Cu3P nanoarray material loaded on the copper mesh includes the following steps: (1) Dissolve 8.412 g (150 mmol) potassium hydroxide (KOH) and 2.02 g (7.50 mmol) potassium persulfate (K2S2O8) in 80 mL of ultrapure water. Stir the mixture thoroughly for 1 h (stirrer speed is 500 rpm) to obtain a homogeneous mixed solution. Then, immerse 3 pieces of 2×4 cm pretreated copper mesh (CW) current collectors (which were ultrasonically cleaned for 10 min in 2 M hydrochloric acid, anhydrous ethanol and deionized water respectively) in the solution. Perform an oxidation etching reaction at 70 °C for 4 h. After the reaction, allow the material to cool naturally to room temperature (25 °C). Wash the cooled material three times with ultrapure water and anhydrous ethanol respectively, and dry it in a forced-air drying oven at 60 °C for 12 h to obtain the Cu(OH)2 nanoarray precursor loaded on the CW.

[0070] (2) The Cu(OH)2 nanoarray material loaded on CW obtained in step (1) was mixed with sodium hypophosphite (gas-solid reaction source material, phosphorus source) at a mass ratio of 1:50 and placed in a mixed gas atmosphere of hydrogen (H2) and argon (Ar) with a volume ratio of 5:95. The gas flow rate was 50 mL / min, and the temperature was raised to 600 ℃ at a heating rate of 12 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 24 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain Cu3P nanoarray material loaded on CW.

[0071] (3) Immerse the Cu3P nanoarray material loaded on the CW obtained in step (2) in sodium tripolyphosphate (Na5P3O4) at a mass percentage of 1% (w / v). 10 After standing in an aqueous solution of sodium tripolyphosphate (STPP) at 60 °C for 18 h, the material was taken out, rinsed three times with ultrapure water, and dried in a forced-air drying oven at 60 °C for 12 h to obtain the sodium tripolyphosphate modified Cu3P nanoarray material loaded on CW, named CW / Cu3P@STPP. Scanning electron microscopy (SEM) analysis was performed on the Cu3P nanoarray material modified with sodium tripolyphosphate loaded on CW obtained in Example 1. The morphology results are as follows: Figure 1 As shown, nanoarray structures are uniformly distributed on the CW.

[0072] Example 2: Cu2S nanoarray material modified with lithium ethylenediaminetetramethylenephosphonate loaded on a copper plate The preparation method of the Cu2S nanoarray material modified with lithium ethylenediaminetetramethylenephosphonate loaded on the copper plate includes the following steps: (1) 42.30 g (500 mmol) sodium bicarbonate (NaHCO3) and 20.40 g (120 mmol) hydrogen peroxide (H2O2, 30%, w / v) were dissolved in 90 mL of ethylene glycol and stirred thoroughly on a stirrer for 2 h (stirrer speed was 450 rpm) to obtain a homogeneous mixed solution. Then, three 3×5 cm copper plate (CP) current collectors were immersed in the solution after pretreatment (in 2 M hydrochloric acid, anhydrous ethanol and deionized water for 10 min respectively). The oxidation etching reaction was carried out at 80 °C for 12 h. After the reaction was completed, the solution was allowed to cool naturally to room temperature (25 °C). The cooled material was washed three times with ethylene glycol and ultrapure water respectively, and dried in a forced-air drying oven at 60 °C for 24 h to obtain the Cu(OH)2 nanoarray precursor loaded on the CP.

[0073] (2) The Cu(OH)2 nanoarray material loaded on CP obtained in step (1) was mixed with thiourea (gas-solid reaction source material, sulfur source) at a mass ratio of 1:20 and placed in a mixed gas atmosphere of hydrogen (H2) and helium (He) with a volume ratio of 5:95. The gas flow rate was 30 mL / min, and the temperature was raised to 700 ℃ at a heating rate of 16 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 12 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain Cu2S nanoarray material loaded on CP.

[0074] (3) Immerse the Cu2S nanoarray material loaded on CP obtained in step (2) in 5% (w / v) lithium ethylenediaminetetramethylenephosphonate (C6H2SO4). 16 N2O 12 After standing in an aqueous solution of P4Li4 (EDTMP·Li) at 50 °C for 12 h, the material was taken out, rinsed three times with ultrapure water, and dried in a forced-air drying oven at 60 °C for 12 h to obtain Cu2S nanoarray material modified with lithium ethylenediaminetetramethylenephosphonate supported on CP, named CP / Cu2S@EDTMP·Li. Scanning electron microscopy (SEM) analysis was performed on the Cu2S nanoarray material modified with lithium ethylenediaminetetramethylenephosphonate loaded on CP obtained in Example 2. The morphology results are as follows: Figure 2 As shown, nanoarray structures are uniformly distributed on CP.

[0075] Example 3: Cu2Se nanoarray material modified with tetrasodium aminotrimethylphosphonate supported on copper foam The preparation method of the tetrasodium aminotrimethylphosphonate nanoarray material loaded on the copper foam includes the following steps: (1) 64.32 g (480 mmol) sodium oxalate (Na2C2O4) and 4.76 g (20 mmol) sodium persulfate (Na2S2O8) were dissolved in 100 mL of methanol and stirred thoroughly on a stirrer for 3 h (stirrer speed was 450 rpm) to obtain a homogeneous mixed solution. Two 4×4 cm pretreated (sonicated in 2 M hydrochloric acid, anhydrous ethanol and deionized water for 10 min respectively) copper foam (CF) current collectors were immersed in the solution and oxidative etching reaction was carried out at 30 °C for 24 h. After the reaction was completed, the solution was allowed to cool naturally to room temperature (25 °C). The cooled material was washed three times with methanol and ultrapure water respectively and dried in a forced-air drying oven at 60 °C for 6 h to obtain Cu(OH)2 nanoarray precursor loaded on CF.

[0076] (2) The Cu(OH)2 nanoarray material loaded on CF obtained in step (1) was mixed with selenium powder (gas-solid reaction source material, selenium source) at a mass ratio of 1:10 and placed in a mixed gas atmosphere of hydrogen (H2) and nitrogen (N2) with a volume ratio of 5:95. The gas flow rate was 10 mL / min, and the temperature was raised to 800 ℃ at a heating rate of 22 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 8 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain Cu2Se nanoarray material loaded on CF.

[0077] (3) The Cu2Se nanoarray material loaded on CF obtained in step (2) was immersed in a 10% (w / v) aqueous solution of tetrasodium aminotrimethylphosphonate (C3H8NO9P3Na4, ATMP·Na4), and after standing at 25 °C for 4 h, it was taken out, rinsed 3 times with ultrapure water, and dried in a forced-air drying oven at 60 °C for 12 h to obtain Cu2Se nanoarray material modified with tetrasodium aminotrimethylphosphonate loaded on CF, named CF / Cu2Se@ATMP·Na4; Scanning electron microscopy (SEM) analysis was performed on the Cu2Se nanoarray material modified with tetrasodium aminotrimethylphosphonate loaded on CF obtained in Example 3. The morphology results are as follows: Figure 3 As shown, nanoarray structures are uniformly distributed on the CF.

[0078] Example 4: Pentaerythritol tetraphosphate tetrapotassium-modified Cu₂Te nanoarray material supported on copper mesh The preparation method of the Cu2Te nanoarray material modified with pentaerythritol tetraphosphate tetrapotassium loaded on the copper mesh includes the following steps: (1) 10.3 g (250 mmol) sodium hydroxide (NaOH) and 4.56 g (20 mmol) ammonium persulfate (NH4)2S2O8 were dissolved in 80 mL of ethanol and stirred thoroughly on a stirrer for 1 h (stirrer speed was 550 rpm) to obtain a homogeneous mixed solution. Then, 4 pieces of 2×3 cm pretreated copper mesh (CW) current collectors (which were ultrasonically cleaned for 10 min in 2 M hydrochloric acid, anhydrous ethanol and deionized water respectively) were immersed in the solution and subjected to an oxidative etching reaction at 40 °C for 8 h. After the reaction was completed, the material was allowed to cool naturally to room temperature (25 °C). The cooled material was washed 3 times with anhydrous ethanol and ultrapure water respectively and dried in a forced-air drying oven at 60 °C for 12 h to obtain Cu(OH)2 nanoarray precursor loaded on CW.

[0079] (2) The Cu(OH)2 nanoarray material loaded on CW obtained in step (1) was mixed with tellurium powder (gas-solid reaction source material, tellurium source) at a mass ratio of 1:100 and placed in a mixed gas atmosphere of hydrogen (H2) and argon (Ar) with a volume ratio of 5:95. The gas flow rate was 22 mL / min, and the temperature was raised to 500 ℃ at a heating rate of 4 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 36 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain Cu2Te nanoarray material loaded on CW.

[0080] (3) The Cu2Te nanoarray material loaded on the CW obtained in step (2) is immersed in 20% (w / v) potassium pentaerythritol tetraphosphate (C5H4H4O2). 12 O 16 After standing in an aqueous solution of P4K4 (PETP·K4) at 40 °C for 2 h, the material was removed, rinsed three times with ultrapure water, and dried in a forced-air drying oven at 60 °C for 6 h to obtain Cu2Te nanoarray material modified with tetrapotassium pentaerythritol tetraphosphate loaded on CW, named CW / Cu2Te@PETP·K4. Scanning electron microscopy (SEM) analysis was performed on the Cu2Te nanoarray material modified with tetrapotassium pentaerythritol tetraphosphate loaded on CW obtained in Example 4. The morphology results are as follows: Figure 4 As shown, nanoarray structures are uniformly distributed on the CW.

[0081] Example 5: Tributyl phosphate modified Cu3P nanoarray material supported on copper mesh The preparation method of the tributyl phosphate modified Cu3P nanoarray material loaded on the copper mesh includes the following steps: (1) Dissolve 8.412 g (150 mmol) potassium hydroxide (KOH) and 2.02 g (7.50 mmol) potassium persulfate (K2S2O8) in 80 mL of ultrapure water. Stir the mixture thoroughly for 1 h (stirrer speed is 500 rpm) to obtain a homogeneous mixed solution. Then, immerse 3 pieces of 2×4 cm pretreated copper mesh (CW) current collectors (which were ultrasonically cleaned for 10 min in 2 M hydrochloric acid, anhydrous ethanol and deionized water respectively) in the solution. Perform an oxidation etching reaction at 70 °C for 4 h. After the reaction, allow the material to cool naturally to room temperature (25 °C). Wash the cooled material three times with ultrapure water and anhydrous ethanol respectively, and dry it in a forced-air drying oven at 60 °C for 12 h to obtain the Cu(OH)2 nanoarray precursor loaded on the CW.

[0082] (2) The Cu(OH)2 nanoarray material loaded on CW obtained in step (1) was mixed with sodium hypophosphite (gas-solid reaction source material, phosphorus source) at a mass ratio of 1:50 and placed in a mixed gas atmosphere of hydrogen (H2) and argon (Ar) with a volume ratio of 5:95. The gas flow rate was 50 mL / min, and the temperature was raised to 600 ℃ at a heating rate of 12 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 24 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain the Cu3P nanoarray material loaded on CW, named CW / Cu3P.

[0083] (3) The Cu3P nanoarray material loaded on CW obtained in step (2) was immersed in a 1% (v / v) tributyl phosphate-(C4H9O)3PO (TBP) aqueous solution (the density of TBP at 25 °C is 0.973 g / mL, the density of water is 1.00 g / mL, that is, the mass percentage of TBP in the TBP aqueous solution is 0.973%, w / v), and after standing at 60 °C for 18 h, it was taken out, rinsed 3 times with ultrapure water, and dried in a forced-air drying oven at 60 °C for 12 h to obtain the Cu3P nanoarray material modified by tributyl phosphate loaded on CW, named CW / Cu3P@TBP.

[0084] Comparative Example 1: Cu3P nanoarray material supported on copper mesh The difference from Example 1 is that sodium tripolyphosphate (Na5P3O) was not used. 10 The method for preparing the Cu3P nanoarray material loaded on the copper mesh, with modifications performed while keeping other conditions unchanged, includes the following steps: (1) Dissolve 8.412 g (150 mmol) potassium hydroxide (KOH) and 2.02 g (7.50 mmol) potassium persulfate (K2S2O8) in 80 mL of ultrapure water. Stir the mixture thoroughly for 1 h (stirrer speed is 500 rpm) to obtain a homogeneous mixed solution. Then, immerse 3 pieces of 2×4 cm pretreated copper mesh (CW) current collectors (which were ultrasonically cleaned for 10 min in 2 M hydrochloric acid, anhydrous ethanol and deionized water respectively) in the solution. Perform an oxidation etching reaction at 70 °C for 4 h. After the reaction, allow the material to cool naturally to room temperature (25 °C). Wash the cooled material three times with ultrapure water and anhydrous ethanol respectively, and dry it in a forced-air drying oven at 60 °C for 12 h to obtain the Cu(OH)2 nanoarray precursor loaded on the CW.

[0085] (2) The Cu(OH)2 nanoarray material loaded on CW obtained in step (1) was mixed with sodium hypophosphite (gas-solid reaction source material, phosphorus source) at a mass ratio of 1:50 and placed in a mixed gas atmosphere of hydrogen (H2) and argon (Ar) with a volume ratio of 5:95. The gas flow rate was 50 mL / min, and the temperature was raised to 600 ℃ at a heating rate of 12 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 24 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain the Cu3P nanoarray material loaded on CW, named CW / Cu3P.

[0086] Comparative Example 2: Cu3P nanoarray material modified with aluminum metaphosphate loaded on copper mesh The difference from Example 1 is that aluminum metaphosphate (Al(PO3)3) is used for modification, while other steps remain unchanged. The preparation method of the aluminum metaphosphate-modified Cu3P nanoarray material loaded on the copper mesh includes the following steps: (1) Dissolve 8.412 g (150 mmol) potassium hydroxide (KOH) and 2.02 g (7.50 mmol) potassium persulfate (K2S2O8) in 80 mL of ultrapure water. Stir the mixture thoroughly for 1 h (stirrer speed is 500 rpm) to obtain a homogeneous mixed solution. Then, immerse 3 pieces of 2×4 cm pretreated CW (which were ultrasonically cleaned for 10 min in 2 M hydrochloric acid, anhydrous ethanol and deionized water respectively) in the solution. Perform an oxidation etching reaction at 70 °C for 4 h. After the reaction, allow the material to cool naturally to room temperature (25 °C). Wash the cooled material three times with ultrapure water and anhydrous ethanol respectively, and dry it in a forced-air drying oven at 60 °C for 12 h to obtain the Cu(OH)2 nanoarray precursor loaded on the CW.

[0087] (2) The Cu(OH)2 nanoarray material loaded on CW obtained in step (1) was mixed with sodium hypophosphite (gas-solid reaction source material, phosphorus source) at a mass ratio of 1:50 and placed in a mixed gas atmosphere of hydrogen (H2) and argon (Ar) with a volume ratio of 5:95. The gas flow rate was 50 mL / min, and the temperature was raised to 600 ℃ at a heating rate of 12 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 24 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain the Cu3P nanoarray material loaded on CW, named CW / Cu3P.

[0088] (3) The Cu3P nanoarray material loaded on CW obtained in step (2) was immersed in an aqueous solution of aluminum metaphosphate (Al(PO3)3) with a mass percentage of 1% (w / v), and after standing at 60 °C for 18 h, it was taken out, rinsed with ultrapure water 3 times, and dried in a forced-air drying oven at 60 °C for 12 h to obtain the Cu3P array material modified with aluminum metaphosphate loaded on CW, named CW / Cu3P@Al(PO3)3.

[0089] Comparative Example 3: Cu2S nanoarray material loaded on a copper plate The difference from Example 2 is that lithium ethylenediaminetetramethylenephosphonate (C6H) was not used. 16 N2O 12 The method for preparing the Cu2S nanoarray material loaded on the copper plate by modifying it with P4Li4, while keeping other step conditions unchanged, includes the following steps: (1) 42.30 g (500 mmol) sodium bicarbonate (NaHCO3) and 20.40 g (120 mmol) hydrogen peroxide (H2O2, 30% wt) were dissolved in 90 mL of ethylene glycol and stirred thoroughly on a stirrer for 2 h (stirrer speed was 450 rpm) to obtain a homogeneous mixed solution. Then, three 3×5 cm copper plate (CP) current collectors were immersed in the solution after pretreatment (in 2 M hydrochloric acid, anhydrous ethanol and deionized water for 10 min respectively). The oxidation etching reaction was carried out at 80 °C for 12 h. After the reaction was completed, the solution was allowed to cool naturally to room temperature (25 °C). The cooled material was washed three times with ethylene glycol 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 CP.

[0090] (2) The Cu(OH)2 nanoarray material loaded on CP obtained in step (1) was mixed with thiourea (gas-solid reaction source material, sulfur source) at a mass ratio of 1:20 and placed in a mixed gas atmosphere of hydrogen (H2) and helium (He) with a volume ratio of 5:95. The gas flow rate was 30 mL / min, and the temperature was raised to 700 ℃ at a heating rate of 16 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 12 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain Cu2S nanoarray material loaded on CP, named CP / Cu2S.

[0091] Comparative Example 4: Cu2Se nanoarray material supported on copper foam The difference from Example 3 is that tetrasodium aminotrimethylphosphonate (C3H8NO9P3Na4) was not used for modification, while other step conditions remained unchanged. The preparation method of the Cu2Se nanoarray material supported on the copper foam includes the following steps: (1) 64.32 g (480 mmol) sodium oxalate (Na2C2O4) and 4.76 g (20 mmol) sodium persulfate (Na2S2O8) were dissolved in 100 mL of methanol and stirred thoroughly on a stirrer for 3 h (stirrer speed was 450 rpm) to obtain a homogeneous mixed solution. Two 4×4 cm pretreated (sonicated in 2 M hydrochloric acid, anhydrous ethanol and deionized water for 10 min respectively) copper foam (CF) current collectors were immersed in the solution and oxidative etching reaction was carried out at 30 °C for 24 h. After the reaction was completed, the solution was allowed to cool naturally to room temperature (25 °C). The cooled material was washed three times with methanol and ultrapure water respectively and dried in a forced-air drying oven at 60 °C for 6 h to obtain Cu(OH)2 nanoarray precursor loaded on CF.

[0092] (2) The Cu(OH)2 nanoarray material loaded on CF obtained in step (1) was mixed with selenium powder (gas-solid reaction source material, selenium source) at a mass ratio of 1:10 and placed in a mixed gas atmosphere of hydrogen (H2) and nitrogen (N2) with a volume ratio of 5:95. The gas flow rate was 10 mL / min, and the temperature was raised to 800 ℃ at a heating rate of 22 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 8 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain Cu2Se nanoarray material loaded on CF (CF / Cu2Se).

[0093] Comparative Example 5: Cu2Te nanoarray material supported on copper mesh The difference from Example 4 is that pentaerythritol tetrapotassium tetraphosphate (C5H) was not used. 12 O 16 The method for preparing the Cu2Te nanoarray material loaded on the copper mesh includes the following steps, with P4K4 modified and other conditions remaining unchanged: (1) 10.3 g (250 mmol) sodium hydroxide (NaOH) and 4.56 g (20 mmol) ammonium persulfate (NH4)2S2O8 were dissolved in 80 mL of ethanol and stirred thoroughly on a stirrer for 1 h (stirrer speed was 550 rpm) to obtain a homogeneous mixed solution. Four 2×3 cm pretreated CWs (which were ultrasonically cleaned for 10 min in 2 M hydrochloric acid, anhydrous ethanol and deionized water respectively) were immersed in the solution and subjected to an oxidative etching reaction at 40 °C for 8 h. After the reaction was completed, the solution was allowed to cool naturally to room temperature (25 °C). The cooled material was washed three times with ethanol and ultrapure water respectively and dried in a forced-air drying oven at 60 °C for 12 h to obtain Cu(OH)2 nanoarray precursor loaded on CWs.

[0094] (2) The Cu(OH)2 nanoarray material loaded on CW obtained in step (1) was mixed with tellurium powder (gas-solid reaction source material, tellurium source) at a mass ratio of 1:100 and placed in a mixed gas atmosphere of hydrogen (H2) and argon (Ar) with a volume ratio of 5:95. The gas flow rate was 22 mL / min, and the temperature was raised to 500 ℃ at a heating rate of 4 ℃ / min. The high-temperature gas-solid purging reaction was carried out for 36 h. After the reaction was completed, it was naturally cooled to room temperature (25 ℃) to obtain Cu2Te nanoarray material loaded on CW, named CW / Cu2Te.

[0095] Application Example 1: Study on the bifunctional wastewater resource recovery performance of electrocatalytic nitrate reduction to ammonia production and coupled anodic sulfur oxidation. 1. Test conditions and parameters Electrochemical measurements were performed using a Koster electrochemical workstation. Key metrics for evaluating the activity of the nanoarray materials prepared in the examples or comparative examples included: the current density (J) required to excite the nanoarrays at the same voltage, the voltage (E) required to achieve the same current density, the ammonia formation rate, and the Faraday efficiency.

[0096] RHE in the following description stands for Reversible Hydrogen Electrode, and Hg / HgO stands for Mercury / Mercury Oxide Reference Electrode.

[0097] 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) of all materials was collected at open-circuit potential before each electrochemical data acquisition. Cyclic voltammetry (CV) curves were then scanned multiple times within a voltage range of -1.3 to 0 V vs. Hg / HgO until stable. Subsequently, linear sweep voltammetry (LSV) tests were performed within the same voltage range, and the LSV curves were compensated for with 80% ohmic voltage drop (IR). According to formula E... （RHE） = E （Hg / HgO） + 0.098 + 0.05916 × pH, the potential value E （Hg / HgO） Convert to E （RHE） .

[0098] 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 1 M KOH (deionized water as solvent); 0.05916 × pH represents the pH term in the Nernst equation.

[0099] 2. Performance testing of electrocatalytic nitrate reduction to ammonia production reaction (NO3RR) The electrocatalytic performance of the nanoarray materials prepared in Examples 1, 5, 1, and 2 for the ammonia production by nitrate reduction (NO3RR) was tested.

[0100] (1) Experimental methods Electrocatalytic activity: The nanoarray materials prepared in Examples 1, 5, 1 (Comparative Example), and 2 (Comparative Example 2) were used as working electrodes (1 × 1 cm⁻¹). 2 ), platinum sheet (1×1 cm) 2 A standard three-electrode system was constructed using a counter electrode (KNO3) and a reference electrode (Hg / HgO). Linear sweep voltammetry (LSV) tests were performed within the voltage range of -1.3 to 0 V vs. Hg / HgO. The electrolyte used was a mixed solution of 0.1 M potassium nitrate (KNO3) and 1 M potassium hydroxide (KOH). When a current was passed through the above three-electrode system, NO3RR occurred at the working electrode. Under alkaline conditions, nitrate (NO3) ions... - It is reduced to NH3.

[0101] Faraday efficiency and ammonia production rate: The electrocatalytic performance of the material for ammonia production from nitrate reduction was tested by chronoamperometry (CA) for 1 h, and the ammonia product was quantitatively analyzed by ultraviolet-visible spectrophotometry (UV-vis), with the characteristic peak located at 420 nm.

[0102] 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 .

[0103] (2) Experimental results See electrocatalytic activity results. Figure 5 The order of electrocatalytic activity of the four examples is: Comparative Example 1 < Comparative Example 2 < Example 5 < Example 1, indicating that the nanoarray materials prepared in Examples 1 and 5 of this invention have better electrocatalytic activity and superior NO3RR performance.

[0104] The ammonia formation rate and Faraday efficiency of the above nanoarray material at -0.4 V vs. RHE, as measured by a UV-Vis spectrophotometer, are shown in Table 1. Table 1. Ammonia formation rate and Faraday efficiency

[0105] As shown in Table 1, the ammonia generation rate and Faraday efficiency of the nanoarray materials obtained in Example 1 and Example 5 are significantly better than those of the nanoarray materials obtained in Comparative Example 1 and Comparative Example 2.

[0106] Stability test results are as follows Figure 6 As shown, after 22 cycles of testing, the ammonia production rate and Faraday efficiency of the nanoarray material obtained in Example 1 remained at a high level, while the nanoarray materials obtained in Comparative Example 1 and Comparative Example 2 were rapidly deactivated, indicating that the nanoarray material obtained in Example 1 has better long-term operational stability.

[0107] 3. Electrocatalytic nitrate reduction to ammonia (NO3RR) || Performance testing of the electrocatalytic unit for methanol oxidation (MOR) The electrocatalytic activity and stability of the electrocatalytic devices (NO3RR || MOR devices) composed of nanoarray materials prepared in Examples 1, 5, 1, and 2, respectively, for the electrocatalytic reaction of nitrate reduction to ammonia production (NO3RR) || methanol oxidation (MOR), were tested. The electrocatalytic device (NO3RR || OER device) composed of nanoarray materials obtained in Example 1 was used as a control group to evaluate the energy-saving advantage of MOR replacing OER. The NO3RR || MOR device composed of nanoarray materials prepared in Example 1 was designated as Device A, the NO3RR || MOR device composed of nanoarray materials prepared in Comparative Example 1 was designated as Device B, and the NO3RR || OER device composed of nanoarray materials prepared in Example 1 was designated as Device C.

[0108] (1) Experimental methods NO3RR || Actual image of the MOR device as shown in the image. Figure 7 As shown: The nanoarray material obtained in Example 1 or Comparative Example 1 is used as the cathode and anode of a bifunctional electrolytic cell (electrocatalytic device). The methanol oxidation reaction (MOR) is coupled to the anode, and the electrocatalytic nitrate reduction to ammonia reaction (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 is deionized water), and the anode electrolyte is a mixed solution of 1 M methanol and 1 M potassium hydroxide. The electrolytes at both electrodes are continuously refreshed during operation to ensure stable reactant concentrations and timely product discharge. When current is applied to the NO3RR || MOR device, NO3RR occurs at the cathode. Under alkaline conditions, nitrate ions (NO3) are produced. - Methanol is reduced to NH3; MOR occurs at the anode, and methanol is oxidized to formic acid (HCOOH).

[0109] NO3RR || OER Device: Using the nanoarray material 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 is deionized water), and the anode electrolyte is 1 M potassium hydroxide (solvent is deionized water). When current is applied to the NO3RR || OER device, NO3RR 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.

[0110] 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 electrocatalytic device was tested.

[0111] (2) Experimental results Electrocatalytic activity results are as follows Figure 8 As shown, the NO3RR || MOR device assembled from the nanoarray material obtained in Example 1 achieves 100 mA / cm². 2 The voltage required for the current density is much lower than that of the NO3RR || MOR device assembled from the nanoarray material obtained in Comparative Example 1, and the NO3RR || OER device assembled from the nanoarray material obtained in Example 1. This indicates that the nanoarray material obtained in Example 1 can significantly reduce the overall electrolysis energy consumption when the anode is coupled to MOR. The above results show that the nanoarray material obtained in Example 1 has both excellent NO3RR and MOR performance, and exhibits significant energy-saving advantages in the NO3RR || MOR device.

[0112] Stability results are as follows Figure 9 As shown, the NO3RR ||MOR device built using the nanoarray material obtained in Example 1 as the anode and cathode can operate stably for at least 720 hours, and can simultaneously realize the ammonia production from the cathode and the formic acid production from the anode, and can simultaneously realize the resource utilization of wastewater from both the anode and cathode.

[0113] Application Example 2: Performance Test of Electrocatalytic Reduction of Nitrate to Ammonia The electrocatalytic activity of the nanoarray materials obtained in Example 2 and Comparative Example 3 for the ammonia production reaction (NO3RR) was tested. A CA test was performed for 1 h at -0.35 V vs. RHE. After completion, samples were taken and the ammonia production rate and Faraday efficiency were measured using UV-vis. The specific testing and calculation procedures are as described in Application Example 1.

[0114] Electrocatalytic activity results are as follows Figure 10 As shown, for NO3RR, the order of electrocatalytic activity is Comparative Example 3 < Example 2, indicating that the nanoarray material prepared in Example 2 of this invention has better electrocatalytic activity.

[0115] Based on UV-vis, the ammonia formation rate and Faraday efficiency of the above nanoarray material at -0.35 V vs. RHE are shown in Table 2: Table 2. Ammonia formation rate and Faraday efficiency

[0116] As shown in Table 2, the ammonia generation rate and Faraday efficiency of the nanoarray material obtained in Example 2 are significantly better than those of the nanoarray material obtained in Comparative Example 3.

[0117] Application Example 3: Study on the performance of electrocatalytic reduction of nitrates to ammonia and coupled anodic sulfur oxidation in the resource recovery of wastewater. 1. Electrocatalytic activity test of nitrate reduction to ammonia (NO3RR) The electrocatalytic activity of the nanoarray materials obtained in Example 3 and Comparative Example 4 in the ammonia production reaction (NO3RR) was tested, and a CA test was performed at -0.25 V vs. RHE for 1 h. After completion, samples were taken and the ammonia production rate and Faraday efficiency were tested by UV-vis. The specific test and calculation process is the same as in Application Example 1.

[0118] Electrocatalytic activity results are as follows Figure 11 As shown, the order of electrocatalytic activity for the electrocatalytic reduction of nitrate to ammonia is Comparative Example 4 < Example 3, indicating that the nanoarray material obtained in Example 3 has better electrocatalytic activity.

[0119] Based on the UV-vis test results, the ammonia formation rate and Faraday efficiency of the above nanoarray material at -0.25 V vs. RHE are shown in Table 3: Table 3. Ammonia formation rate and Faraday efficiency

[0120] As shown in Table 3, the ammonia generation rate and Faraday efficiency of the nanoarray material obtained in Example 3 are significantly better than those of the nanoarray material obtained in Comparative Example 4.

[0121] 2. Electrocatalytic reduction of nitrate to ammonia (NO3RR) || Performance testing of electrocatalytic unit for sulfur oxidation reaction (SOR) The electrocatalytic activity and stability of the electrocatalytic devices for nitrate reduction to ammonia (NO3RR) || sulfur oxidation (SOR) composed of the nanoarray materials obtained in Example 3 and Comparative Example 4 (NO3RR || SOR device) were tested respectively. The electrocatalytic device for nitrate reduction to ammonia (NO3RR) || oxygen evolution reaction (OER) assembled with the nanoarray materials prepared in Example 3 (NO3RR || OER device) was used as a control group to evaluate the energy-saving advantage of SOR replacing OER. The NO3RR || SOR device composed of the nanoarray materials prepared in Example 3 was designated as device D, the NO3RR || SOR device composed of the nanoarray materials prepared in Comparative Example 4 was designated as device E, and the NO3RR || OER device composed of the nanoarray materials prepared in Example 3 was designated as device F.

[0122] (1) Experimental methods A physical image of the NO3RR || SOR device is shown below. Figure 12 As shown: The nanoarray material obtained in Example 3 is used as the cathode and anode of a bifunctional electrolytic cell. The sulfur oxidation reaction (SOR) is coupled to the anode, and the electrocatalytic nitrate reduction to ammonia reaction (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 a mixed solution containing 1 M sodium sulfide and 1 M sodium hydroxide (solvent: deionized water). The electrolytes at both electrodes are continuously refreshed during operation to ensure stable reactant concentrations and timely product discharge. When current is applied to the NO3RR ||SOR device, NO3RR occurs at the cathode. Under alkaline conditions, nitrate (NO3) ions are produced. - ) is reduced to NH3; SOR occurs at the anode, and sulfide ions (S 2- It is oxidized to elemental sulfur.

[0123] NO3RR || OER Device: Using the nanoarray material obtained in Example 3 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 is deionized water), and the anode electrolyte is 1 M potassium hydroxide (solvent is deionized water). When current is applied to the NO3RR || OER device, NO3RR 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.

[0124] Refer to Application Example 1 for the specific testing procedure.

[0125] (2) Experimental results Electrocatalytic activity results are as follows Figure 13 As shown, the NO3RR || SOR device assembled from the nanoarray material obtained in Example 3 achieved 100 mA / cm². 2 The voltage required for the current density is much lower than that of the NO3RR || SOR device assembled from the nanoarray material obtained in Comparative Example 4 and the NO3RR || OER device assembled from the nanoarray material obtained in Example 3. This indicates that the nanoarray material obtained in Example 3 can significantly reduce the overall electrolysis energy consumption when the anode is coupled to SOR. The above results show that the nanoarray material obtained in Example 3 has both excellent NO3RR and SOR performance, and exhibits significant energy-saving advantages in the NO3RR || SOR device.

[0126] Stability test results are as follows Figure 14 As shown, the nanoarray material obtained in Example 3, when used to construct a NO3RR|| SOR device with cathode and anode, can operate stably for at least 480 hours. It can simultaneously realize the production of ammonia from the cathode and the production of elemental sulfur from the anode, and can simultaneously realize the resource utilization of wastewater from both cathode and anode.

[0127] Application Example 4: Performance Test of Electrocatalytic Reduction of Nitrate to Ammonia The electrocatalytic activity of the nanoarray materials obtained in Example 4 and Comparative Example 5 for nitrate reduction to ammonia (NO3RR) was tested. A CA test was performed at -0.3 V vs. RHE for 1 h. After completion, samples were taken and the ammonia production rate and Faraday efficiency were tested using UV-vis. The specific testing and calculation procedures are as described in Application Example 1.

[0128] Electrocatalytic activity results are as follows Figure 15 As shown, for NO3RR, their electrocatalytic activity order is Comparative Example 5 < Example 4, indicating that the nanoarray material obtained in Example 4 of this invention has better electrocatalytic activity.

[0129] Based on UV-vis, the ammonia formation rate and Faraday efficiency of the above nanoarray material at -0.3 V vs. RHE are shown in Table 4: Table 4. Ammonia formation rate and Faraday efficiency

[0130] As shown in Table 4, the ammonia generation rate and Faraday efficiency of the nanoarray material obtained in Example 4 are significantly better than those of the nanoarray material obtained in Comparative Example 5.

[0131] 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 surface-modified copper-based compound nanoarray electrode material, characterized in that, The preparation process includes the following steps: S1: The copper-based current collector is immersed in a solution containing a precipitant and an oxidant to carry out an oxidative etching reaction, followed by post-treatment to obtain a copper hydroxide nanoarray precursor grown in situ on the copper-based current collector. S2: The copper hydroxide nanoarray precursor grown in situ on the copper-based current collector obtained in step S1 is mixed with the gas-solid reaction source material and placed in a reducing gas atmosphere. A high-temperature gas-solid conversion reaction is carried out at 500~800 ℃ to obtain copper-based compound nanoarray material loaded on the copper-based current collector. S3: The copper-based compound nanoarray material loaded on the copper-based current collector obtained in step S2 is immersed in a solution containing phosphoric acid compounds and left to stand for surface modification. After post-treatment, the surface-modified copper-based compound nanoarray electrode material is obtained. The gas-solid reaction source material is selected from at least one of sodium hypophosphite, thiourea, selenium powder, and tellurium powder. The mass ratio of the copper hydroxide nanoarray precursor to the gas-solid reaction source material is 1:(10~100). The phosphate compound is selected from at least one of sodium tripolyphosphate, lithium ethylenediaminetetramethylenephosphonate, tetrasodium aminotrimethylenephosphonate, tetrapotassium pentaerythritol tetraphosphate, and tributyl phosphate.

2. The surface-modified copper-based compound nanoarray electrode material as described in claim 1, characterized in that, The precipitant is selected from at least one of potassium hydroxide, sodium hydroxide, sodium bicarbonate, and sodium oxalate.

3. The surface-modified copper-based compound nanoarray electrode material as described in claim 1, characterized in that, The oxidant is selected from at least one of ammonium persulfate, hydrogen peroxide, potassium persulfate, sodium persulfate, and hypochlorite.

4. The surface-modified copper-based compound nanoarray electrode material as described in claim 1, characterized in that, The concentration of the phosphoric acid-containing compound solution is 0.9 w / v% to 20 w / v.

5. The surface-modified copper-based compound nanoarray electrode material as described in claim 1, characterized in that, The reducing gas atmosphere contains hydrogen.

6. An electrocatalytic device, characterized in that, The electrocatalytic device includes a power source, a membrane, a cathode, an anode, a cathode chamber, and an anode chamber. The materials of the anode and cathode each contain at least one of the surface-modified copper-based compound nanoarray electrode materials described in any one of claims 1 to 5.

7. The application of the surface-modified copper-based compound nanoarray electrode material according to any one of claims 1 to 5 in the electrocatalytic reduction of nitrate to ammonia and / or oxidation reaction, characterized in that, The oxidation reaction is either a sulfur oxidation reaction or a methanol oxidation reaction.

8. The application of the electrocatalytic device according to claim 6 in the electrocatalytic reduction of nitrate to ammonia and / or oxidation reaction, characterized in that, The oxidation reaction is either a sulfur oxidation reaction or a methanol oxidation reaction.

9. The application as described in claim 8, characterized in that, The oxidation reaction is subject to at least one of the following conditions: (1) The sulfur oxidation reaction converts sulfur ions into elemental sulfur; (2) The methanol oxidation reaction converts methanol into formic acid.

10. A method for treating wastewater, characterized in that, Wastewater is treated using the electrocatalytic device of claim 6, wherein the wastewater includes anode wastewater and cathode wastewater, the anode wastewater being methanol-containing wastewater or sulfur-containing wastewater, and the cathode wastewater being nitrate-containing wastewater.

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