Method for Electrochemically Reducing Nitric Oxide to Hydroxylamine Based on Single-Atom Iron Catalyst

Abstract

The present invention relates to the technical field of single-atom metal catalysts, and particularly to a method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom iron catalyst. First, the single-atom metal catalyst and Nafion are dissolved in isopropanol to obtain a mixed solution, and then the mixed solution is drop-coated onto carbon paper and post-treated to obtain a working electrode; then a flow-through electrolytic cell is used to construct a two-compartment three-electrode reaction system; finally, nitric oxide is introduced, and an overpotential is applied to the working electrode to carry out an electrochemical reaction to obtain hydroxylamine. The present invention uses a single-atom iron catalyst to electrochemically reduce toxic and harmful nitric oxide gas into hydroxylamine with high added value, and has high activity and high yield; moreover, the electrochemical reaction carried out by the present invention is carried out at normal temperature and pressure, and no harmful by-products are generated.

Description

Technical Field

[0001] The present invention relates to the technical field of single-atom metal catalysts, and particularly to a method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom iron catalyst. Background Art

[0002] Nitric oxide (NO) not only causes global warming but also triggers environmental problems such as acid rain. Traditional nitric oxide removal processes need to be optimized due to harsh operating conditions and sacrificing high-value chemicals. Selective catalytic reduction is currently an effective method for eliminating nitric oxide, but it has problems such as high operating costs / potential secondary pollution and low sustainability. Generally, ammonia water or hydrogen is used as a reducing agent, and it can be converted into harmless nitrogen at a temperature above 300°C. As one of the important intermediates for electrochemical denitrification, electrochemical reduction of nitric oxide (NOR) is an ideal system for studying the electroreduction of nitrate.

[0003] Electrocatalytic reduction of nitric oxide is widely regarded as a promising sustainable development technology. The reduction products are mostly ammonia, hydroxylamine, nitrogen, hydrogen, nitrous oxide, and nitrogen. Hydroxylamine, as an important chemical raw material, is an important raw material for synthesizing nylon monomer caprolactam and has a wide range of uses in industries such as pesticides and pharmaceuticals. With the rapid development of the chemical industry, the uses of hydroxylamine are also constantly expanding, especially its role in clean and safe chemical production is gradually emerging. At present, there are few research reports on electroreducing nitric oxide to hydroxylamine, and its reaction mechanism is not yet clear. It is urgent for researchers to explore its reaction mechanism. Single-atom metal catalysts have the advantages of a high active surface area and can achieve the maximum atomic utilization rate. They have also been widely used in reactions such as CO2RR and HER, but their applications in NORR are very few. Therefore, reducing nitric oxide to hydroxylamine by a low-cost and structurally well-defined single-atom catalyst is of great significance and is conducive to clarifying the reaction mechanism. Summary of the Invention

[0004] To solve the above problems, the purpose of the present invention is to provide a method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom iron catalyst. First, the single-atom metal catalyst and Nafion are dissolved in isopropanol to obtain a mixed solution, and then the mixed solution is drop-coated onto carbon paper and post-treated to obtain a working electrode. Then, a flow-through electrolytic cell is used to build a two-compartment three-electrode reaction system. Finally, nitric oxide is introduced, and an overpotential is applied to the working electrode to carry out an electrochemical reaction to obtain hydroxylamine. The present invention uses a single-atom iron catalyst to electrochemically reduce the toxic and harmful nitric oxide gas into high-value-added hydroxylamine, which has high activity and high yield. Moreover, the electrochemical reaction carried out in the present invention is carried out at normal temperature and pressure without the generation of harmful by-products.

[0005] The working principle of the present invention is as follows: Since the iron-based catalyst is prone to form a complex with the reactant gas, making it difficult to break the nitrogen-oxygen bond, hydroxylamine is thus the main product of the electroreduction of nitric oxide.

[0006] NO(g)+4H + (aq)+3e - →NH3OH + (aq).

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom iron catalyst, comprising the following steps:

[0009] (1) Preparation of the working electrode: Dissolve the single-atom iron catalyst and Nafion in isopropanol to obtain a mixed solution, then drop-coat the mixed solution onto carbon paper and perform post-treatment to obtain the working electrode;

[0010] (2) Setup of the electrochemical device: Use a flow-through electrolytic cell, and use the working electrode prepared in step (1) as the working electrode of the flow-through electrolytic cell to set up a two-compartment three-electrode reaction system;

[0011] (3) Electrochemical reaction: Pass nitric oxide and apply an overpotential to the working electrode to carry out an electrochemical reaction to obtain hydroxylamine.

[0012] In one embodiment of the present invention, in step (1), the chemical structural formula of the single-atom iron catalyst is shown in formula (I):

[0013]

[0014] In one embodiment of the present invention, the single-atom iron catalyst polymerizes on graphene with metallic iron as the porphyrin central atom to form a covalent organic framework, increasing the active surface area and achieving the maximum utilization rate of atoms.

[0015] In one embodiment of the present invention, in step (1), the dosage ratio of the single-atom iron catalyst, Nafion and isopropanol is 1-3 mg: 0.1 mL: 0.9 mL.

[0016] In one embodiment of the present invention, in step (1), the loading amount of the single-atom iron catalyst on the carbon paper is 0.1-0.3 mg / cm -2 .

[0017] In one embodiment of the present invention, the area of the carbon paper used is 3 cm 2 , and 300 μL of the mixed solution is drop-coated onto the carbon paper.

[0018] In one embodiment of the present invention, in step (1), the post-treatment is to irradiate the carbon paper under an infrared lamp for 20 - 50 min.

[0019] In one embodiment of the present invention, in step (2), the mobile phase electrolytic cell uses a peristaltic pump and a gas-liquid mixed flow pump as power sources.

[0020] In one embodiment of the present invention, in step (2), in the dual-cell three-electrode reaction system, the working electrode prepared in step (1) is used as the working electrode of the mobile phase electrolytic cell, a silver / silver chloride electrode is used as the reference electrode, and a platinum sheet is used as the counter electrode.

[0021] In one embodiment of the present invention, the reaction area of the working electrode is 1 cm 2 。

[0022] In one embodiment of the present invention, in step (2), in the mobile phase electrolytic cell, a sodium sulfate solution is used as the electrolyte;

[0023] The concentration of the sodium sulfate solution is 0.5 M and the pH is 1.

[0024] In one embodiment of the present invention, in step (3), a sodium hydroxide solution is installed in front of the nitric oxide gas inlet to remove the nitrogen dioxide gas contained in the gas.

[0025] In one embodiment of the present invention, in step (3), argon is introduced for 15 min before the electrochemical reaction to exclude oxygen in the electrolytic cell.

[0026] In one embodiment of the present invention, the yield of hydroxylamine is determined by ultraviolet spectrophotometry; the specific steps are as follows:

[0027] The ultraviolet spectrophotometry method: Take 1 mL of a diluted solution with an appropriate concentration, add 200 μL of trichloroacetic acid, 200 μL of 8-hydroxyquinoline, and 1 mL of sodium carbonate, place it in boiling water, and heat for 2 minutes. The color changes from light yellow to blue-green, and there is a maximum absorption wavelength at a wavelength of 700 nm. Similarly, dilute the hydroxylamine aqueous solution with deionized water into a series of standard solutions with concentration gradients to obtain a fitted linear standard curve, and use this curve to quantify hydroxylamine.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention uses a single-atom iron catalyst to electrochemically reduce the toxic and harmful nitric oxide gas into hydroxylamine with high added value, and has high activity and high yield.

[0030] (2) The electrochemical reaction carried out by the present invention is carried out under normal temperature and pressure, and no harmful by-products are produced. Description of the Drawings

[0031] Figure 1 It is the standard curve graph of hydroxylamine ultraviolet color development.

[0032] Figure 2 It is the Faraday efficiency graph in Example 2.

[0033] Figure 3 It is the transmission electron microscope graph of the single-atom iron catalyst in Example 2. Detailed Implementation Modes

[0034] The present invention provides a method for electrochemically reducing nitric oxide to produce hydroxylamine based on a single-atom iron catalyst, comprising the following steps:

[0035] (1) Preparation of the working electrode: Dissolve the single-atom iron catalyst and Nafion in isopropanol to obtain a mixed solution, then drop the mixed solution onto carbon paper, and perform post-treatment to obtain the working electrode;

[0036] (2) Construction of the electrochemical device: Adopt a flow-through electrolytic cell, use the working electrode prepared in step (1) as the working electrode of the flow-through electrolytic cell, and construct a two-compartment three-electrode reaction system;

[0037] (3) Electrochemical reaction: Pass nitric oxide and apply an overpotential to the working electrode to carry out an electrochemical reaction to obtain hydroxylamine.

[0038] In one embodiment of the present invention, in step (1), the chemical structural formula of the single-atom iron catalyst is shown in formula (I):

[0039]

[0040] In one embodiment of the present invention, the single-atom iron catalyst polymerizes with metallic iron as the porphyrin central atom on graphene to form a covalent organic framework, increasing the active surface area and achieving the maximum atomic utilization rate.

[0041] In one embodiment of the present invention, in step (1), the dosage ratio of the single-atom iron catalyst, Nafion and isopropanol is 1-3 mg: 0.1 mL: 0.9 mL.

[0042] In one embodiment of the present invention, in step (1), the loading amount of the single-atom iron catalyst on the carbon paper is 0.1-0.3 mg / cm -2 .

[0043] In one embodiment of the present invention, the area of the carbon paper used is 3 cm 2 , and 300 μL of the mixed solution is dropped onto the carbon paper.

[0044] In one embodiment of the present invention, in step (1), the post-treatment is to irradiate the carbon paper under an infrared lamp for 20 - 50 min.

[0045] In one embodiment of the present invention, in step (2), the mobile phase electrolytic cell uses a peristaltic pump and a gas-liquid mixed flow pump as power sources.

[0046] In one embodiment of the present invention, in step (2), in the dual-cell three-electrode reaction system, the working electrode prepared in step (1) is used as the working electrode of the mobile phase electrolytic cell, silver / silver chloride is used as the reference electrode, and a platinum sheet is used as the counter electrode.

[0047] In one embodiment of the present invention, the reaction area of the working electrode is 1 cm 2 。

[0048] In one embodiment of the present invention, in step (2), in the mobile phase electrolytic cell, a sodium sulfate solution is used as the electrolyte;

[0049] The concentration of the sodium sulfate solution is 0.5 M and the pH is 1.

[0050] In one embodiment of the present invention, in step (3), a sodium hydroxide solution is installed in front of the nitric oxide gas inlet to remove nitrogen dioxide gas contained in the gas.

[0051] In one embodiment of the present invention, in step (3), argon is introduced for 15 min before the electrochemical reaction to exclude oxygen in the electrolytic cell.

[0052] In one embodiment of the present invention, the yield of hydroxylamine is determined by ultraviolet spectrophotometry; the specific steps are as follows:

[0053] The ultraviolet spectrophotometry method: Take 1 mL of a diluted solution with an appropriate concentration, add 200 μL of trichloroacetic acid, 200 μL of 8-hydroxyquinoline, and 1 mL of sodium carbonate, place it in boiling water, and heat for 2 minutes. The color changes from light yellow to blue-green, and there is a maximum absorption wavelength at a wavelength of 700 nm. Similarly, dilute the hydroxylamine aqueous solution with deionized water into a series of standard solutions with concentration gradients to obtain a fitted linear standard curve, and use this curve to quantify hydroxylamine.

[0054] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] In the following examples, unless otherwise specified, the reagents used are commercially available reagents, and the detection means and methods used are conventional detection means and methods in the art.

[0056] Example 1

[0057] This embodiment provides a method for determining the content of hydroxylamine by ultraviolet spectrophotometry, which includes the following steps:

[0058] Take 1 mL of a solution with an appropriate diluted concentration, add 200 μL of trichloroacetic acid, 200 μL of 8-hydroxyquinoline, and 1 mL of sodium carbonate, place it in boiling water, and heat for 2 minutes. The color changes from light yellow to blue-green, and there is a maximum absorption wavelength at a wavelength of 700 nm. Similarly, dilute the hydroxylamine aqueous solution with deionized water into a series of standard solutions with concentration gradients to obtain a fitted linear standard curve, and quantify hydroxylamine using this curve ( Figure 1 ).

[0059] Example 2

[0060] This embodiment is based on a method for electrochemically reducing nitric oxide to produce hydroxylamine using a single-atom iron catalyst, which includes the following steps:

[0061] (1) Take a one-milliliter centrifuge tube, add 3 mg of single-atom iron catalyst, 100 μL of Nafion, and 900 μL of isopropanol respectively to form a black mixed suspension, and ultrasonically treat it for 30 minutes to make it uniformly mixed. Take 300 μL of the mixed solution and drop-coat it onto a double-sided hydrophobic carbon paper with an area of 3 cm 2 , and irradiate it under an infrared lamp for 30 minutes to fully dry the catalyst to obtain a working electrode.

[0062] (2) Assemble an electrochemical working cell (a flow-through electrolytic cell, using a peristaltic pump and a gas-liquid mixing pump as power sources, using 0.5 M sodium sulfate as the electrolyte with a pH of 1), and perform an electrochemical reaction using a two-compartment three-electrode system. Use the working electrode prepared in step (1) (with a reaction area of 1 cm 2 ) as the working electrode of the flow-through electrolytic cell, a silver / silver chloride electrode as the reference electrode, and a platinum sheet as the counter electrode.

[0063] (3) Before the nitric oxide gas inlet, there is a washing bottle containing 5 M sodium hydroxide solution to remove nitrogen dioxide impurities. Before the reaction, purge with argon for 30 minutes to remove the oxygen in the air, fill the volume of the electrolytic cell, and introduce nitric oxide to make it fully saturated.

[0064] (4) Apply a series of overpotentials using an electrochemical workstation to perform an electrochemical reaction, and collect the electrolyte after reacting for 30 minutes.

[0065] (5) Take 0.9 ml of deionized water and 0.1 g of trichloroacetic acid and add them to a 15 mL glass bottle to form developer I; take 0.99 ml of ethanol and 0.01 g of 8-hydroxyquinoline and add them to a 15 mL glass bottle to form developer II; take 4.24 g of sodium carbonate and 40 mL of deionized water and add them to a 50 mL centrifuge tube to form developer III. Take 1 mL of the diluted electrolyte, 200 μL of trichloroacetic acid, 200 μL of 8-hydroxyquinoline, and 1 mL of sodium carbonate, add them to a 15 mL glass bottle, and place it in boiling water and heat for 2 minutes. The color changes from light yellow to blue-green, and there is a maximum absorption wavelength at a wavelength of 700 nm. The selectivity and activity of the electroreduction of nitric oxide to hydroxylamine at a series of potentials were tested ( Figure 2 ), in addition, the maximum yield of hydroxylamine was calculated to be 3.1 mmol cm -2 h -1 .

[0066] Among them, the chemical structural formula of the single-atom iron catalyst is shown as follows, and its transmission electron microscope image is as Figure 3 shown:

[0067]

[0068] Example 3

[0069] The method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom iron catalyst in this example includes the following steps:

[0070] (1) Take a 1 mL centrifuge tube, add 2 mg of single-atom iron catalyst, 100 μL of Nafion, and 900 μL of isopropanol respectively to form a black mixed suspension, and ultrasonically treat it for 30 minutes to make it evenly mixed. Take 100 μL of the mixed solution and drop-coat it onto a double-sided hydrophobic carbon paper with an area of 3 cm 2 , and irradiate it under an infrared lamp for 20 minutes to fully dry the catalyst to obtain a working electrode.

[0071] (2) Assemble an electrochemical working cell (flow-through electrolytic cell, using a peristaltic pump and a gas-liquid mixing pump as power sources, using 0.5 M sodium sulfate as the electrolyte, pH = 1), and perform an electrochemical reaction using a two-compartment three-electrode system. Use the working electrode prepared in step (1) (the reaction area is 1 cm 2 ) as the working electrode of the flow-through electrolytic cell, a silver / silver chloride electrode as the reference electrode, and a platinum sheet as the counter electrode.

[0072] (3) A washing bottle containing 5 M sodium hydroxide solution is installed in front of the nitric oxide gas inlet to remove nitrogen dioxide impurities. Before the reaction, argon is introduced for 30 minutes to remove the oxygen in the air, fill the volume of the electrolytic cell, and introduce nitric oxide to make it fully saturated.

[0073] (4) A series of overpotentials were applied using an electrochemical workstation to carry out an electrochemical reaction, and the electrolyte solution was collected after 30 minutes of reaction.

[0074] (5) Take 0.9 ml of deionized water and 0.1 g of trichloroacetic acid and add them to a 15 mL glass bottle to form developer I; take 0.99 ml of ethanol and 0.01 g of 8-hydroxyquinoline and add them to a 15 mL glass bottle to form developer II; take 4.24 g of sodium carbonate and 40 mL of deionized water and add them to a 50 mL centrifuge tube to form developer III. Respectively take 1 mL of the diluted electrolyte solution, 200 μL of trichloroacetic acid, 200 μL of 8-hydroxyquinoline, and 1 mL of sodium carbonate, add them to a 15 mL glass bottle, and place it in boiling water and heat for 2 minutes. Among them, the color changes from light yellow to blue-green, and there is a maximum absorption wavelength at a wavelength of 700 nanometers. Calculate the maximum yield of hydroxylamine as 2.05 mmol cm -2 h -1 .

[0075] Among them, the chemical structural formula of the single-atom iron catalyst is shown as follows:

[0076]

[0077] Example 4

[0078] The method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom iron catalyst in this example includes the following steps:

[0079] (1) Take a 1 ml centrifuge tube, add 1 mg of single-atom iron catalyst, 100 μL of Nafion, and 900 μL of isopropanol respectively to form a black mixed suspension, and ultrasonically process it for 30 minutes to make it uniformly mixed. Take 200 μL of the mixed solution and drop-coat it onto a double-sided hydrophobic carbon paper with an area of 3 cm 2 , and irradiate it under an infrared lamp for 50 minutes to fully dry the catalyst to obtain a working electrode.

[0080] (2) Assemble an electrochemical working cell (a flow-through electrolytic cell, using a peristaltic pump and a gas-liquid mixing pump as power sources, using 0.5 M sodium sulfate as the electrolyte solution with a pH of 1), and carry out an electrochemical reaction using a two-compartment three-electrode system. Use the working electrode prepared in step (1) (the reaction area is 1 cm 2 ) as the working electrode of the flow-through electrolytic cell, use silver / silver chloride as the reference electrode, and use a platinum sheet as the counter electrode.

[0081] (3) A washing bottle containing 5 M sodium hydroxide solution is installed in front of the nitric oxide gas inlet to remove nitrogen dioxide impurities. Before the reaction, argon is introduced for 30 minutes to remove the oxygen in the air, fill the volume of the electrolytic cell, and introduce nitric oxide to make it fully saturated.

[0082] (4) A series of overpotentials were applied using an electrochemical workstation to carry out an electrochemical reaction, and the electrolyte solution was collected after 30 minutes of reaction.

[0083] (5) Take 0.9 ml of deionized water and 0.1 g of trichloroacetic acid and add them to a 15 mL glass bottle to form color reagent I; take 0.99 ml of ethanol and 0.01 g of 8-hydroxyquinoline and add them to a 15 mL glass bottle to form color reagent II; take 4.24 g of sodium carbonate and 40 mL of deionized water and add them to a 50 mL centrifuge tube to form color reagent III. Respectively take 1 mL of the diluted electrolyte solution, 200 μL of trichloroacetic acid, 200 μL of 8-hydroxyquinoline, and 1 mL of sodium carbonate, add them to a 15 mL glass bottle, and place it in boiling water and heat for 2 minutes. Among them, the color changes from light yellow to blue-green, and there is a maximum absorption wavelength at a wavelength of 700 nanometers. Calculate the maximum yield of hydroxylamine as 0.94 mmol cm -2 h -1 。

[0084] Among them, the chemical structural formula of the single-atom iron catalyst is shown as follows:

[0085]

[0086] Comparative Example 1

[0087] This comparative example is based on a method for electrochemically reducing nitric oxide to hydroxylamine using a single-atom cobalt catalyst, including the following steps:

[0088] (1) Take a 1 mL centrifuge tube, add 3 mg of single-atom cobalt catalyst, 100 μL of Nafion, and 900 μL of isopropanol respectively to form a black mixed suspension, and ultrasonically treat it for 30 minutes to make it uniformly mixed. Take 300 μL of the mixed solution and drop-coat it onto a double-sided hydrophobic carbon paper with an area of 3 cm 2 , and irradiate it under an infrared lamp for 30 minutes to fully dry the catalyst to obtain a working electrode.

[0089] (2) Assemble an electrochemical working cell (flow-through electrolytic cell, using a peristaltic pump and a gas-liquid mixing pump as power sources, using 0.5 M sodium sulfate as the electrolyte solution, pH = 1), and carry out an electrochemical reaction using a two-compartment three-electrode system. Use the working electrode prepared in step (1) (the reaction area is 1 cm 2 ) as the working electrode of the flow-through electrolytic cell, use silver / silver chloride as the reference electrode, and a platinum sheet as the counter electrode.

[0090] (3) A gas washing bottle containing 5 M sodium hydroxide solution is installed in front of the nitric oxide gas inlet to remove nitrogen dioxide impurities. Before the reaction, argon is introduced for 30 minutes to remove the oxygen in the air, filling the volume of the electrolytic cell, and then nitric oxide is introduced to make it fully saturated.

[0091] (4) A series of overpotentials were applied using an electrochemical workstation to carry out an electrochemical reaction, and the electrolyte solution was collected after 30 minutes of reaction.

[0092] (5) Take 0.9 ml of deionized water and 0.1 g of trichloroacetic acid and add them to a 15 mL glass bottle to form color reagent I; take 0.99 ml of ethanol and 0.01 g of 8-hydroxyquinoline and add them to a 15 mL glass bottle to form color reagent II; take 4.24 g of sodium carbonate and 40 mL of deionized water and add them to a 50 mL centrifuge tube to form color reagent III. Respectively take 1 mL of the diluted electrolyte solution, 200 μL of trichloroacetic acid, 200 μL of 8-hydroxyquinoline, and 1 mL of sodium carbonate, add them to a 15 mL glass bottle, and place it in boiling water and heat for 2 minutes. Among them, the color changes from light yellow to blue-green, and there is a maximum absorption wavelength at a wavelength of 700 nanometers. Calculate the hydroxylamine yield to be 163 μmol cm -2 h -1 。

[0093] Among them, the chemical structural formula of the single-atom cobalt catalyst is shown as follows:

[0094]

[0095] Comparative Example 2

[0096] This comparative example is a method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom nickel catalyst, including the following steps:

[0097] (1) Take a 1 mL centrifuge tube, add 3 mg of single-atom nickel catalyst, 100 μL of Nafion, and 900 μL of isopropanol respectively to form a black mixed suspension, and ultrasonically treat it for 30 minutes to make it uniformly mixed. Take 300 μL of the mixed solution and drop-coat it onto a double-sided hydrophobic carbon paper with an area of 3 cm 2 , and irradiate it under an infrared lamp for 30 minutes to fully dry the catalyst to obtain a working electrode.

[0098] (2) Assemble an electrochemical working cell (flow-through electrolytic cell, using a peristaltic pump and a gas-liquid mixing pump as power sources, using 0.5 M sodium sulfate as the electrolyte solution with a pH of 1), and carry out an electrochemical reaction using a two-compartment three-electrode system. Use the working electrode prepared in step (1) (with a reaction area of 1 cm 2 ) as the working electrode of the flow-through electrolytic cell, use silver / silver chloride as the reference electrode, and a platinum sheet as the counter electrode.

[0099] (3) Before the nitric oxide gas inlet, there is a washing bottle containing 5 M sodium hydroxide solution to remove nitrogen dioxide impurities. Before the reaction, argon is introduced for 30 minutes to remove the oxygen in the air, filling the volume of the electrolytic cell, and then nitric oxide is introduced to make it fully saturated.

[0100] (4) A series of overpotentials are applied using an electrochemical workstation to carry out an electrochemical reaction, and the electrolyte solution is collected after 30 minutes of reaction.

[0101] (5) Take 0.9 ml of deionized water and 0.1 g of trichloroacetic acid and add them to a 15 mL glass bottle to form developer I; take 0.99 ml of ethanol and 0.01 g of 8-hydroxyquinoline and add them to a 15 mL glass bottle to form developer II; take 4.24 g of sodium carbonate and 40 mL of deionized water and add them to a 50 mL centrifuge tube to form developer III. Respectively take 1 mL of the diluted electrolyte solution, 200 μL of trichloroacetic acid, 200 μL of 8-hydroxyquinoline, and 1 mL of sodium carbonate, add them to a 15 mL glass bottle, and place it in boiling water and heat for 2 minutes. Among them, the color changes from light yellow to blue-green, and there is a maximum absorption wavelength at a wavelength of 700 nanometers. Calculate the hydroxylamine yield to be 204 μmol cm -2 h -1 .

[0102] Among them, the chemical structural formula of the single-atom nickel catalyst is shown as follows:

[0103]

[0104] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom iron catalyst, characterized in that, It includes the following steps: (1) Preparation of the working electrode: Dissolve the single-atom iron catalyst and Nafion in isopropanol to obtain a mixed solution, then drop the mixed solution onto the carbon paper and perform post-treatment to obtain the working electrode; (2) Setup of the electrochemical device: Use a flow-through electrolytic cell, and use the working electrode prepared in step (1) as the working electrode of the flow-through electrolytic cell to set up a two-compartment three-electrode reaction system; (3) Electrochemical reaction: Pass nitric oxide and apply an overpotential to the working electrode to carry out an electrochemical reaction to obtain hydroxylamine; Among them, in step (1), the chemical structural formula of the single-atom iron catalyst is shown in formula (I):

2. The method for electrochemically reducing nitric oxide to produce hydroxylamine based on a single-atom iron catalyst according to claim 1, wherein In step (1), the dosage ratio of the single-atom iron catalyst, Nafion and isopropanol is 1-3 mg: 0.1 mL: 0.9 mL.

3. The method for electrochemically reducing nitric oxide to produce hydroxylamine based on a single-atom iron catalyst according to claim 1, wherein In step (1), the loading amount of the single-atom iron catalyst on the carbon paper is 0.1-0.3 mg / cm -2 .

4. The method for electrochemically reducing nitric oxide to hydroxylamine based on a single-atom iron catalyst according to claim 1, wherein In step (1), the post-treatment is to irradiate the carbon paper under an infrared lamp for 20-50 min.

5. The method for electrochemically reducing nitric oxide to produce hydroxylamine based on a single-atom iron catalyst according to claim 1, wherein In step (2), the flow-through electrolytic cell uses a peristaltic pump and a gas-liquid mixed flow pump as the power source.

6. The method for electrochemically reducing nitric oxide to produce hydroxylamine based on a single-atom iron catalyst according to claim 1, wherein In step (2), in the flow-through electrolytic cell, sodium sulfate solution is used as the electrolyte; The concentration of the sodium sulfate solution is 0.5 M and the pH is 1.

7. The method for electrochemically reducing nitric oxide to produce hydroxylamine based on a single-atom iron catalyst according to claim 1, wherein In step (2), in the two-compartment three-electrode reaction system, silver / silver chloride is used as the reference electrode and a platinum sheet is used as the counter electrode.

8. The method for electrochemically reducing nitric oxide to produce hydroxylamine based on a single-atom iron catalyst according to claim 1, wherein In step (3), the reaction area of the working electrode is 1 cm 2 .

9. The method for electrochemically reducing nitric oxide to produce hydroxylamine based on a single-atom iron catalyst according to claim 1, wherein In step (3), argon is passed for 15 min before the electrochemical reaction to remove oxygen in the electrolytic cell.

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