A dual-site cu-based catalyst for electrocatalytic reduction of nitrogen-containing pollutants / n2o to ammonia and its preparation method and application

Abstract

The application provides a dual-site Cu-based catalyst for electrocatalytic reduction of nitrogen-containing pollutants / N2O to synthesize ammonia, and a preparation method and application thereof, and the preparation method comprises the following steps: S1: dissolving polymeric carbon in an organic solvent to obtain a mixed solution A, and immersing a Cu2O catalyst in the mixed solution A to obtain a mixed solution B; the mixed solution B is heated to volatilize the organic solvent, and a polymeric carbon / Cu2O powder is obtained; wherein the amount of the polymeric carbon is 1% to 10% of the mass of the Cu2O catalyst; S2: the polymeric carbon / Cu2O powder is ground and annealed in an inert atmosphere, and a polymeric carbon / Cu2O catalyst is obtained after cooling. By introducing the polymeric carbon into the Cu2O catalyst, the adsorption strength of nitrogen-containing pollutants and nitrogen intermediates and the dissociation strength of H2O can be balanced, and the performance of the Cu-based catalyst for electrocatalytic reduction of nitrogen-containing pollutants / N2O to synthesize NH3 is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalysis, and relates to a dual-site Cu-based catalyst for electrocatalytic reduction of nitrogen-containing pollutants / N2O to synthesize ammonia as well as a preparation method and application thereof. BACKGROUND

[0002] Industrial production will emit a large amount of NO x waste gas and N2O greenhouse gas. NO x is an important precursor of environmental problems such as photochemical haze, low-altitude ozone, haze, acid rain, and water eutrophication, and N2O will cause ozone layer destruction. Therefore, the emission reduction of NO x and N2O is imminent. At present, NO x and N2O in flue gas are respectively converted into harmless N2 by catalytic reduction and catalytic decomposition, however, these methods often require high temperature of 350 DEG C or above, which will consume considerable energy. At the same time, if the oxidation absorption method is used to remove NO x , a large amount of NO3 – and NO2 – wastewater will be produced.

[0003] By using the abandoned electricity in green electricity to drive electrocatalysis, all nitrogen-containing pollutants can be converted into energy storage material ammonia (NH3). This method is expected to solve the problems of high energy consumption and large carbon dioxide emission existing in the Haber-Bosch method currently used for traditional ammonia preparation, and ammonia as an important raw material for chemical fertilizers and chemical products has more value-added benefits than nitrogen. In this method, the development of efficient electrocatalysts is the core of the whole technology.

[0004] Due to the electronic orbital characteristics, copper (Cu) based catalysts are easy to form strong chemical bonds with nitrogen-containing pollutants and nitrogen intermediates, promoting their reduction. However, due to the strong covalent bond HO-H bond (about 492 kJ / mol) of H2O, the supply of active hydrogen (H) produced by the dissociation of H2O on the surface of pure Cu catalyst is insufficient. Therefore, the balance of the adsorption strength of nitrogen-containing pollutants and nitrogen intermediates and the dissociation strength of H2O has a great influence on the NH3 yield and Faraday efficiency of Cu-based catalysts for electrocatalytic synthesis.

[0005] Studies have shown that the synthesis of Cu 0 / Cu 1+ interface can provide Cu 0 -Cu 1+ asymmetric sites for Cu-based catalysts, Cu 0 and Cu 1 +The strong electron interaction between them can effectively improve the adsorption strength of the material to nitrogen-containing pollutants and nitrogen intermediates and the dissociation strength of H2O. Reference 1 provides a method for regulating Cu 0 -Cu 1+ Asymmetric dual-site method for electrocatalytic NO3 - reaction, but due to the redox potential of Cu 1+ / Cu 0 is 0.521V, it is difficult to ensure that Cu2O can maintain Cu 0 -Cu 1+ Asymmetric dual-site method for electrocatalytic NO3

[0006] Reference 2 provides a C 60 buffered Cu / SiO2 method for synthesizing ethylene glycol at ambient pressure, in which C 60 / Cu / SiO2 material is synthesized, and the electronic buffer effect of C 60 is used to regulate the electronic structure of Cu 0 species for the thermal catalytic synthesis of ethylene glycol.

[0007] It can be seen that although a series of studies have been conducted on copper-based catalysts for the electrocatalytic synthesis of ammonia in the art, the research is not sufficient and there is still room for further exploration.

[0008] Reference:

[0009] Reference 1: Lu Y et al. Size-effect induced controllable Cu 0 -Cu + sites for ampere-level nitrate electroreduction coupled with biomass upgrading[J]. Nature Communications, 2025, 16(1). DOI:10.1038 / s41467-025-57097-x.

[0010] Reference 2: Zheng J et al. Ambient-pressure synthesis of ethylene glycol catalyzed by C 60 -buffered Cu / SiO2[J]. Science, 2022, 376, 288-292. DOI:10.1126 / science.abm9257. SUMMARY

[0011] Problems to be solved by the Invention

[0012] Based on the above problems, the present application provides a preparation method of a dual-site Cu-based catalyst for electrocatalytic reduction of nitrogen-containing pollutants / N2O to synthesize ammonia, which introduces polymerized carbon into Cu2O catalyst to form Cu 0 / Cu 1+ interface on the surface of Cu2O catalyst, providing Cu 0 -Cu 1+ asymmetric sites, while maintaining Cu 0 -Cu 1+ asymmetric sites, balancing the adsorption strength of nitrogen-containing pollutants and nitrogen intermediates and the dissociation strength of H2O, and improving the performance of the Cu-based catalyst in electrocatalytic reduction of nitrogen-containing pollutants / N2O to synthesize NH3.

[0013] In addition, the present application also provides a dual-site Cu-based catalyst prepared by the above method, which is a polymerized carbon-loaded Cu2O catalyst.

[0014] Further, the present application also provides a method for electrocatalytic reduction of nitrogen-containing pollutants / N2O to synthesize ammonia, which uses an electrode loaded with the above dual-site Cu-based catalyst as a working electrode to improve its electrocatalytic performance.

[0015] Solution to the problem

[0016] The present application first provides a preparation method of a dual-site Cu-based catalyst for electrocatalytic reduction of nitrogen-containing pollutants / N2O to synthesize ammonia, which comprises the following steps:

[0017] S1: Dissolve polymerized carbon in an organic solvent to obtain a mixed solution A, immerse Cu2O catalyst in the mixed solution A to obtain a mixed solution B, and heat the mixed solution B to volatilize the organic solvent to obtain polymerized carbon / Cu2O powder; wherein the amount of polymerized carbon is 1% to 10% of the mass of Cu2O catalyst;

[0018] S2: Grind the polymerized carbon / Cu2O powder and anneal it in an inert atmosphere to obtain a polymerized carbon / Cu2O catalyst after cooling.

[0019] According to the preparation method of the present application, the polymerized carbon comprises carbon atom clusters with a carbon atom number of 20 to 100; and / or,

[0020] The organic solvent comprises one or more of benzene, toluene, cumene, bromoform, m-xylene, chlorobenzene, 1,2,3-tribromopropane, carbon disulfide, tetrahydronaphthalene, 1,2,4-trichlorobenzene, 1,2-dichlorobenzene, 1-methylnaphthalene, and 1-chloronaphthalene; and / or,

[0021] The concentration of the polymeric carbon in the mixed solution A is 3.5 g / L or less.

[0022] According to the preparation method, in the step S1, the dissolving is ultrasonic dissolving, and the ultrasonic dissolving time is 15 min to 60 min.

[0023] The impregnating is ultrasonic impregnating, and the ultrasonic impregnating time is 15 min to 60 min.

[0024] The heating temperature is 50℃ to 80℃.

[0025] According to the preparation method, in the step S2, the inert gas in the inert atmosphere includes one or more of nitrogen, argon and helium.

[0026] In the annealing step, the temperature increasing rate is 1 to 5℃ / min, and the annealing temperature is 150 to 350℃.

[0027] According to the preparation method, the preparation of the Cu2O catalyst includes the following steps:

[0028] (1) dissolving a Cu precursor salt in ultrapure water to obtain a Cu precursor salt solution;

[0029] (2) dissolving NaOH in ultrapure water to obtain a NaOH solution;

[0030] (3) slowly adding the NaOH solution to the Cu precursor salt solution, stirring until mixed uniformly, then adding D-(+)-glucose and heating, and then filtering, washing and drying to obtain the Cu2O catalyst.

[0031] According to the preparation method, the Cu precursor salt includes one or more of copper nitrate, copper nitrate trihydrate, copper sulfate, copper sulfate pentahydrate, copper chloride, copper chloride dihydrate, copper acetate or copper acetate monohydrate; and / or,

[0032] The resistivity of the ultrapure water is 18.2 MΩ cm; and / or,

[0033] The molar concentration of the Cu precursor salt solution is 0.03 to 0.1 mol / L; and / or,

[0034] The molar concentration of the NaOH solution is 0.5 to 2 mol / L; and / or,

[0035] The amount of ultrapure water in the NaOH solution is 0.5 to 0.7 times the amount of ultrapure water in the Cu precursor salt solution; and / or,

[0036] The added amount of the D-(+)-glucose is 0.15-0.25 g corresponding to 1 mmol of Cu precursor salt; and / or,

[0037] The heating temperature is 50-70℃, and the heating time is 2-4 h.

[0038] In addition, the application also provides a dual-site Cu-based catalyst prepared by the preparation method. 0 -Cu 1+ Asymmetric site.

[0039] Further, the application also provides a method for synthesizing ammonia by electrocatalytic reduction of nitrogen-containing pollutants / N2O, comprising the following steps:

[0040] (I) mixing a second organic solvent, ultrapure water, a Nafion solution and the polymeric carbon / Cu2O catalyst prepared by the preparation method to coat the surface of carbon paper or carbon cloth, and drying to obtain a working electrode;

[0041] (II) assembling a three-electrode system with the working electrode, a counter electrode and a reference electrode, inserting into an electrolyte solution to form an electrolytic cell, and synthesizing ammonia by electrocatalytic reduction of nitrogen-containing pollutants and / or N2O.

[0042] According to the method, the nitrogen-containing pollutants include one or more of nitrate, nitrite, nitric oxide, nitrogen dioxide or nitrous oxide.

[0043] According to the method, the second organic solvent includes isopropyl alcohol or ethanol; and / or,

[0044] The density of the polymeric carbon / Cu2O catalyst loaded on the working electrode is 0.5-1.5 mg / cm 2 ; and / or,

[0045] The potential of the working electrode is 0~-1.2 vs. RHE.

[0046] Effects of the application

[0047] 1. The preparation method of the dual-site Cu-based catalyst introduces polymeric carbon into the Cu2O catalyst. The electronic buffering effect of the polymeric carbon can transfer electrons to Cu2O, reducing part of the Cu 1+ on the surface of the catalyst to Cu 0 , forming a Cu 0 / Cu 1+ interface, and providing Cu 0 -Cu 1+Asymmetric sites. In the reduction condition, Cu 1+ will be reduced to Cu 0 , and the polymeric carbon can obtain the electron of Cu species, so that it keeps a certain proportion of Cu 1+ sites, thereby maintaining the Cu 0 -Cu 1+ asymmetric sites. The adsorption strength of the material to nitrogen-containing pollutants, nitrogen intermediates and the dissociation strength of H2O are effectively improved, and the NH3 yield and Faraday efficiency are improved.

[0048] 2、The method for synthesizing ammonia by electrocatalytically reducing nitrogen-containing pollutants / N2O provided by the application improves the electrocatalytic performance by using the electrode loaded with the dual-site Cu-based catalyst prepared by the application as the working electrode, and the method has low energy consumption, high NH3 yield and high Faraday efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 (a) in FIG. 1 shows the XRD test graph of the 5wt% polymeric carbon / Cu2O catalyst in Example 2, Figure 1 (b) in FIG. 1 shows the XPS test graph of the 5wt% polymeric carbon / Cu2O catalyst in Example 2;

[0050] Figure 2 (a) in FIG. 2 shows the proportion of Cu 1+ in the 5wt% polymeric carbon / Cu2O catalyst in Example 2 under the reduction condition;

[0051] Figure 3 (a) in FIG. 3 shows the NH3 yield and Faraday efficiency of the electrocatalytic reduction of NO to synthesize NH3 by using Cu2O and the 5wt% polymeric carbon / Cu2O catalyst under the working voltage of-1.1 V vs. RHE in Example 4;

[0052] Figure 4 (a) in FIG. 4 shows the NH3 yield of the electrocatalytic reduction of N2O to synthesize NH3 by using the 5wt% polymeric carbon / Cu2O catalyst under the working voltage of-0.4 V vs. RHE in Example 5;

[0053] Figure 5 (a) in FIG. 5 shows the NH3 yield and Faraday efficiency of the electrocatalytic reduction of NO3 - to synthesize NH3 by using Cu2O and the 5wt% polymeric carbon / Cu2O catalyst under the working voltage of-1.1 V vs. RHE in Example 6;

[0054] Figure 6 (a) in FIG. 6 shows the NH3 yield and Faraday efficiency of the electrocatalytic reduction of NO3 -LSV curve;

[0055] Figure 7 The electrocatalytic reduction of NO2 by Cu2O and 5wt% polymerized carbon / Cu2O catalyst in Example 7 is shown at a working voltage of -1.1 V vs. RHE. - The NH3 yield and Faraday efficiency of NH3 synthesis. Detailed Implementation

[0056] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0057] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0058] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0059] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0060] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0061] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0062] [First aspect]

[0063] The first aspect of this invention provides a method for preparing a two-site Cu-based catalyst for the electrocatalytic reduction of nitrogen-containing pollutants / N2O to ammonia, comprising the following steps:

[0064] S1: dissolving the polymeric carbon in an organic solvent to obtain a mixed solution A, immersing the Cu2O catalyst in the mixed solution A to obtain a mixed solution B, heating the mixed solution B to volatilize the organic solvent, and obtaining a polymeric carbon / Cu2O powder; wherein the amount of the polymeric carbon is 1%-10% of the mass of the Cu2O catalyst;

[0065] S2: grinding the polymeric carbon / Cu2O powder, annealing in an inert atmosphere, and obtaining a polymeric carbon / Cu2O catalyst after cooling.

[0066] (Step S1)

[0067] In step S1 of the present application, the polymeric carbon is dissolved in an organic solvent to obtain a mixed solution A, the Cu2O catalyst is immersed in the mixed solution A to obtain a mixed solution B, and the mixed solution B is heated to volatilize the organic solvent, and a polymeric carbon / Cu2O powder is obtained. By combining the polymeric carbon with the Cu2O, a Cu 0 / Cu 1+ interface can be formed on the surface of the Cu2O, and a Cu 0 -Cu 1+ asymmetric site is provided.

[0068] The polymeric carbon in the present application refers to a carbon aggregate with a definite structure composed of a plurality of carbon atoms through chemical bonds. In some specific embodiments, the polymeric carbon includes carbon atom clusters with a carbon atom number of 20-100. The polymeric carbon in the present application not only forms a Cu 0 / Cu 1+ interface on the surface of the copper-based catalyst, provides a Cu 0 -Cu 1+ asymmetric site, but also maintains the Cu 0 -Cu 1+ asymmetric site through its electronic buffering effect in the reduction process of the copper-based catalyst, thereby balancing the adsorption strength of the nitrogen-containing pollutants and nitrogen intermediates and the dissociation strength of H2O, and improving the performance of the copper-based catalyst in the electrocatalytic reduction of the nitrogen-containing pollutants / N2O to synthesize NH3.

[0069] The amount of the polymeric carbon is 1%-10% of the mass of the Cu2O catalyst, for example, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc. When the amount of the polymeric carbon is 1%-10% of the mass of the Cu2O catalyst, the Cu 0 -Cu 1+ asymmetric site on the surface of the Cu2O catalyst and the effect of maintaining the double site can be achieved. When the amount of the polymeric carbon is less than 1%, the above effects are difficult to achieve, and when the amount of the polymeric carbon exceeds 10%, the amount tends to be saturated, and the above effects cannot continue to be effectively improved.

[0070] In some specific embodiments, the organic solvent can include one or more of benzene, toluene, cumene, bromoform, m-xylene, chlorobenzene, 1,2,3-tribromopropane, carbon disulfide, tetralin, 1,2,4-trichlorobenzene, 1,2-dichlorobenzene, 1-methylnaphthalene, 1-chloronaphthalene.

[0071] In some specific embodiments, the concentration of polymeric carbon in the mixed solution A is 3.5 g / L or less, for example, it can be 3 g / L, 2 g / L, 1 g / L, 0.5 g / L, 0.2 g / L, 0.1 g / L, etc.

[0072] In some specific embodiments, from the perspective of improving the solubility of polymeric carbon, the dissolving can use ultrasonic dissolving, and the time of the ultrasonic dissolving can be 15 min to 60 min.

[0073] In some specific embodiments, in order to fully impregnate the Cu2O catalyst, the impregnation can use ultrasonic impregnation, and the time of the ultrasonic impregnation can be 15 min to 60 min.

[0074] In some specific embodiments, the temperature of the heating is 50°C to 80°C, for example, it can be 55°C, 60°C, 65°C, 70°C, 75°C, etc. There is no particular limitation on the mode of the heating, which can be selected as needed, for example, water bath heating, etc., and in addition, as preferred, in order to further improve the efficiency of the volatilization of the organic solvent, the heating can be carried out in a fume hood.

[0075] There is no particular limitation on the preparation method of the Cu2O catalyst in the present application, which can be prepared by using a method commonly used in the art, and in some preferred embodiments, the preparation of the Cu2O catalyst can include the following steps:

[0076] (1) Dissolve a Cu precursor salt in ultrapure water to obtain a Cu precursor salt solution;

[0077] (2) Dissolve NaOH in ultrapure water to obtain a NaOH solution;

[0078] (3) Slowly add the NaOH solution to the Cu precursor salt solution, stir until mixed evenly, then add D-(+)-glucose, and heat, and then filter, wash, and dry to obtain a Cu2O catalyst.

[0079] In some specific embodiments, the Cu precursor salt can include one or more of copper nitrate (Cu(NO3)2), copper nitrate trihydrate (Cu(NO3)2·3H2O), copper sulfate (CuSO4), copper sulfate pentahydrate (CuSO4·5H2O), copper chloride (CuCl2), copper chloride dihydrate (CuCl2·2H2O), copper acetate (Cu(CO2CH3)2), or copper acetate monohydrate (Cu(CO2CH3)2·H2O).

[0080] For the ultrapure water, it means water with a resistivity of 18.2 MΩ cm at room temperature.

[0081] In some specific embodiments, the molar concentration of the Cu precursor salt is 0.03-0.1 mol / L, for example, it can be 0.05 mol / L, 0.07 mol / L, 0.09 mol / L, etc. Preferably, in order to fully dissolve the Cu precursor salt, the Cu precursor salt solution can be stirred and mixed, and the stirring and mixing time can be 5-10 min.

[0082] In some specific embodiments, the molar concentration of the NaOH solution is 0.5-2 mol / L, for example, it can be 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, etc. Preferably, in order to fully dissolve the NaOH, the NaOH solution can be stirred and mixed, and the stirring and mixing time can be 5-10 min.

[0083] In some specific embodiments, the amount of ultrapure water used in the NaOH solution is 0.5-0.7 times the amount of ultrapure water used in the Cu precursor salt solution, for example, it can be 0.55 times, 0.6 times, 0.65 times, etc. Preferably, in order to fully mix the NaOH solution and the Cu precursor salt solution, the mixed solution can be stirred and mixed, and the stirring and mixing time can be 15-45 min.

[0084] In some specific embodiments, the amount of D-(+)-glucose added is 0.15-0.25 g per 1 mmol of Cu precursor salt.

[0085] In some specific embodiments, the temperature of the heating and stirring is 50-70°C, for example, it can be 55°C, 60°C, 65°C, etc.; and the heating and stirring time is 2-4 h, for example, it can be 2.5 h, 3 h, 3.5 h, etc.

[0086] (Step S2)

[0087] The step S2 of the present application is to grind the polymeric carbon / Cu2O powder, anneal in an inert atmosphere, and obtain a polymeric carbon / Cu2O catalyst after cooling, wherein the polymeric carbon / Cu2O catalyst is a dual-site Cu-based catalyst. In this step, the annealing step can stabilize the combination of the polymeric carbon and Cu2O.

[0088] In some specific embodiments, the inert gas used in the inert atmosphere can include one or more of nitrogen (N2), argon (Ar), and helium (He).

[0089] In some specific embodiments, in the annealing step, the heating rate is 1-5°C / min, for example, it can be 2°C / min, 3°C / min, 4°C / min, etc.; the annealing temperature is 150-350°C, for example, it can be 200°C, 250°C, 300°C, etc. Under the above annealing conditions, the binding force of the polymeric carbon and Cu2O can be effectively enhanced. When the annealing temperature is lower than 150°C, the above effect is difficult to achieve, and when the annealing temperature is higher than 350°C, the polymeric carbon can be decomposed.

[0090] [Second aspect]

[0091] The second aspect of the present application provides a dual-site Cu-based catalyst, which is a polymeric carbon-supported Cu2O catalyst prepared according to the preparation method of the first aspect of the present application, and has Cu 0 -Cu 1+ Asymmetric sites.

[0092] [Third aspect]

[0093] The third aspect of the present application provides a method for electrocatalytic reduction of nitrogen-containing pollutants / N2O to synthesize ammonia, which comprises the following steps:

[0094] (I) mixing a second organic solvent, ultrapure water, a Nafion solution, and a polymeric carbon / Cu2O catalyst prepared according to the preparation method of the first aspect of the present application, and coating on the surface of carbon paper or carbon cloth, and drying to obtain a working electrode;

[0095] (II) assembling a three-electrode system with the working electrode, a counter electrode, and a reference electrode, inserting into an electrolyte solution to form an electrolytic cell, and synthesizing ammonia from nitrogen-containing pollutants and / or N2O by an electrocatalytic method.

[0096] In some specific embodiments, the nitrogen-containing pollutants can include one or more of nitrate (NO3 - ), nitrite (NO2 - ), nitric oxide (NO), or nitrogen dioxide (NO2), etc.

[0097] In some specific embodiments, the second organic solvent can be isopropanol or ethanol, preferably isopropanol.

[0098] In some specific embodiments, the density of the polymeric carbon / Cu2O catalyst loaded on the working electrode is 0.5-1.5 mg / cm2. 2 For example, it can be 0.8 mg / cm2, 1 mg / cm2, 1.2 mg / cm2, 1.4 mg / cm2, etc. 2 2 2 2

[0099] In some specific embodiments, the ratio of the amount of the second organic solvent, ultrapure water, Nafion (perfluorosulfonic acid-based polymer) solution and polymeric carbon / Cu2O catalyst is (960-980) μL:(10-30) μL:(5-15) μL:(3-8) mg, preferably, the ratio of the amount is 970 μL:20 μL:10 μL:5 mg.

[0100] As for the kind of the counter electrode, the present application is not particularly limited, and a counter electrode commonly used in the art can be used, for example, Pt, etc.

[0101] As for the kind of the reference electrode, the present application is not particularly limited, and a reference electrode commonly used in the art can be used, for example, it can be a reversible hydrogen reference electrode (RHE).

[0102] In some specific embodiments, the potential of the working electrode is 0- -1.2 V vs. RHE, for example, it can be -0.2 V vs. RHE, -0.5 V vs. RHE, -0.8 V vs. RHE, -1 V vs. RHE, -1.1 V vs. RHE, etc. Generally, when the voltage is lower than 0.521 V vs. RHE, Cu2O will be reduced to Cu 0 However, in the present application, due to the electronic buffering effect of the polymeric carbon, Cu2O still exists on the surface of the catalyst at the above-mentioned working voltage. 1+

[0103] As for the kind of the electrolyte solution, the present application is not particularly limited, and an electrolyte solution commonly used in the art can be used.

[0104] Examples

[0105] ​​​​​The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. The specific conditions not noted in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not noted by the manufacturer, which are all conventional products that can be obtained by purchase.

[0106] Example 1

[0107] This example relates to the preparation of a 1wt% polymeric carbon / Cu2O catalyst, and the specific operation is as follows:

[0108] (1) Select copper chloride dihydrate (CuCl2·2H2O) as the Cu precursor salt, weigh 1.534g of CuCl2·2H2O and dissolve in 150mL of ultrapure water, stir for 10min, and prepare A liquid.

[0109] (2) Weigh 7.2g of NaOH and dissolve in 90mL of ultrapure water, stir for 10min, and prepare B liquid.

[0110] (3) Slowly add B liquid to A liquid, stir for 30min. Then add D-(+)-glucose 1.8g, heat in water bath at 60℃ for 3h, then wash with water, suction filtration, and wash to obtain Cu2O catalyst, and dry under vacuum at 60℃ for 12h for standby.

[0111] (4) Weigh 3mg of polymeric carbon C 60 , dissolve in 15mL of toluene, and ultrasonic dissolve for 30min. Then add 300mg of Cu2O catalyst, ultrasonic impregnate for 30min, then transfer to a beaker, heat in water bath at 60℃ until the organic solvent is completely volatilized, to obtain 1wt% polymeric carbon / Cu2O powder.

[0112] (5) Then grind the 1wt% polymeric carbon / Cu2O powder, and anneal at 200℃ for 2h at a heating rate of 2℃ / min under Ar atmosphere, to prepare 1wt% polymeric carbon / Cu2O catalyst.

[0113] Example 2

[0114] This example relates to the preparation of a 5wt% polymeric carbon / Cu2O catalyst, which is different from example 1 in that the amount of polymeric carbon C 60 used in step (4) of example 1 is changed to 15mg, and the remaining steps are the same as example 1, to obtain 5wt% polymeric carbon / Cu2O catalyst.

[0115] The 5wt% polymeric carbon / Cu2O catalyst is tested by XRD and XPS, and the XRD test results of the 5wt% polymeric carbon / Cu2O catalyst are as follows:Figure 1 As shown in (a) above, the XPS test results are as follows: Figure 1 As shown in (b) of the diagram. Figure 1 As can be seen in (a), after adding 5wt% polymerized carbon, the XRD test results show that the 5wt% polymerized carbon / Cu2O catalyst is a mixture of Cu2O and Cu, and is composed of... Figure 1 As can be seen in (b), XPS testing further confirms that the 5wt% polymerized carbon / Cu2O catalyst simultaneously possesses Cu 0 Site and Cu 1+ The site, while Cu in the XPS test results 2+ This may be due to surface oxidation of the catalyst during the testing process.

[0116] Cu in the electrocatalytic reduction process of 5wt% polymerized carbon / Cu2O catalyst 1+ Species such as Figure 2 As shown. Generally, when the voltage is below 0.521 V vs. RHE, Cu₂O will be reduced to Cu. 0 ,Depend on Figure 2 It can be seen that even under a negative voltage of -0.8 to -0.9 V vs. RHE, Cu can still be detected on the surface of a 5wt% polymerized carbon / Cu2O catalyst. 1+ As can be seen, by adding polymerized carbon, the Cu2O catalyst was maintained under reducing conditions. 0 -Cu 1+ The effect of asymmetric sites.

[0117] Example 3

[0118] This embodiment relates to the preparation of a 10wt% polymeric carbon / Cu2O catalyst, which differs from Example 1 in that the polymeric carbon C in step (4) of Example 1 is used in this embodiment. 60 The dosage was changed to 30 mg, and the remaining steps were the same as in Example 1, to obtain a 10 wt% polymerized carbon / Cu2O catalyst.

[0119] Comparative Example 1

[0120] This comparative example relates to the preparation of a Cu2O catalyst, the preparation method of which is shown in steps (1) to (3) of Example 1, to obtain the Cu2O catalyst.

[0121] Example 4

[0122] This embodiment relates to a method for electrocatalytic reduction of NO to synthesize ammonia, and the specific operation is as follows:

[0123] (1) Take 5 mg of 5wt% polymeric carbon / Cu2O catalyst in Example 2 and 5 mg of Cu2O in Comparative Example 1, respectively, and mix with 970 μL of isopropyl alcohol, 20 μL of ultrapure water and 10 μL of Nafion solution to prepare Ink solution.

[0124] (2) Ultrasonic the Ink solution for 30 min to make it uniformly dispersed. Apply it on carbon paper with an application area of 1 1 cm and an application amount of 0.5 mg / cm 2 , and use it as working electrode.

[0125] (3) Insert the working electrode coated with the Ink solution, a Pt sheet (counter electrode) and a reference electrode into an electrolyte solution to form an electrolytic cell, and perform electrocatalytic reduction of NO to synthesize NH3 at a potential of -1.1 V vs. RHE for 30 min.

[0126] Test the NH3 yield and Faraday efficiency of electrocatalytic reduction of NO to synthesize NH3 by Cu2O and 5wt% polymeric carbon / Cu2O catalyst at a working voltage of -1.1 V vs. RHE. The specific test method is as follows: pass 1% NO / Ar gas at a flow rate of 10 mL / min into the electrolyte solution for 30 min, then pass 1% NO / Ar gas at a flow rate of 10 mL / min while performing the experiment at a specified working voltage for 30 min, and determine the NH3 concentration in the electrolyte solution after the experiment by spectrophotometry. The results are shown in Figure 3 . It can be seen from Figure 3 that Cu2O has an NH3 yield of >1 mg h -1 mg cat -2 and a Faraday efficiency of >28% in electrocatalytic reduction of NO. The electrocatalytic performance of 5wt% polymeric carbon / Cu2O catalyst is greatly improved (NH3 yield increased by more than 20%, and Faraday efficiency increased by more than 45%).

[0127] Example 5

[0128] This example relates to a method for electrocatalytic reduction of N2O to synthesize ammonia, and the specific operation is as follows:

[0129] (1) Take 5 mg of 5wt% polymeric carbon / Cu2O catalyst in Example 2 and mix with 970 μL of isopropyl alcohol, 20 μL of ultrapure water and 10 μL of Nafion solution to prepare Ink solution.

[0130] (2) Ultrasonic the Ink solution for 30 min to make it uniformly dispersed. Apply it on carbon paper with an application area of 1 1 cm and an application amount of 0.5 mg / cm 2, which is used as the working electrode.

[0131] (3) The coated working electrode, Pt sheet (counter electrode) and reference electrode are inserted into the electrolyte solution to form an electrolytic cell, and the electrocatalytic reduction of NO to NH3 is carried out at -0.4 V vs. RHE for 30 min.

[0132] The NH3 yield and Faraday efficiency of the electrocatalytic reduction of N2O to NH3 by the 5wt% polymerized carbon / Cu2O catalyst at -0.4 V vs. RHE working voltage are tested. The specific test method is as follows: 30 min of Ar gas with a flow rate of 10 mL / min is introduced into the electrolyte solution, followed by 1% NO / Ar gas with a flow rate of 10 mL / min, and then the experiment is carried out at the specified working voltage for 6 h, and the NH3 yield and Faraday efficiency are calculated by the following formula: Figure 4 It can be seen that the NH3 yield of the electrocatalytic reduction of N2O to NH3 by the 5wt% polymerized carbon / Cu2O catalyst is 0.64 mg 6h -1 mg cat -2 .

[0133] Example 6

[0134] This example relates to a method for the electrocatalytic reduction of NO3 - to NH3, and the specific operation is as follows:

[0135] (1) 5 mg of the catalyst prepared in Examples 1-3 and Comparative Example 1 is weighed, respectively, and is mixed with 970 μL of isopropyl alcohol, 20 μL of ultrapure water and 10 μL of Nafion solution to prepare an Ink solution.

[0136] (2) The working electrode is prepared in the same way as in Example 4, and the size of the working electrode is 0.5 0.5 cm, and the coating amount is 1 mg / cm 2 .

[0137] (3) The coated working electrode, Pt sheet (counter electrode) and reference electrode are inserted into the electrolyte solution to form an electrolytic cell, and the electrocatalytic reduction of NO3 - to NH3 is carried out at -1.1 V vs. RHE for 60 min in the H-type electrolytic cell.

[0138] The NH3 yield and Faraday efficiency of the electrocatalytic reduction of NO3 - to NH3 by Cu2O and 5wt% polymerized carbon / Cu2O catalyst at -1.1 V vs. RHE working voltage are tested, and the results are shown in Figure 5 . It can be seen that the NH3 yield of the electrocatalytic reduction of NO3 Figure 5 to NH3 by Cu2O is 0.45 mg 6h .- When >37 mg h -1 mg cat -2 The NH3 yield and Faraday efficiency were high. Electrocatalytic NO3 production with a 5 wt% polymeric carbon / Cu2O catalyst was achieved. - Performance significantly improved (NH3 yield > 58 mg h) -1 mg cat -2 Faraday efficiency > 85%.

[0139] Electrocatalytic NO3- oxidizing agents were tested in an H-type electrolyzer from 0 to -1.2 V vs. RHE voltage range using Cu2O, 1 wt% polycarbonate / Cu2O, 5 wt% polycarbonate / Cu2O, and 10 wt% polycarbonate / Cu2O catalysts. - The operating current at that time was plotted, and the LSV curve was generated. The test results are as follows: Figure 6 As shown. By Figure 6 It can be seen that when using polymerized carbon C 60 After regulating the Cu2O dual-site, electrocatalysis of NO3 - The performance of all of them has been significantly improved.

[0140] Example 7

[0141] This embodiment relates to an electrocatalytic reduction of NO2. - The specific steps for synthesizing ammonia are as follows:

[0142] (1) The preparation of the Ink solution and the fabrication of the working electrode are the same as in Case 4, except that the size of the working electrode is 0.5 mm. 0.5cm, coating amount is 1 mg / cm 2 .

[0143] (2) The coated working electrode, Pt sheet (counter electrode), and reference electrode are combined to form a three-electrode system, which is then inserted into the electrolyte solution to form an electrolytic cell. Electrocatalytic reduction of NO2 is carried out in an H-type electrolytic cell at a potential of -1.1 V vs. RHE for 60 min. - The reaction for synthesizing NH3.

[0144] Electrocatalytic reduction of NO2 by Cu2O and 5wt% polymerized carbon / Cu2O catalyst was tested at an operating voltage of -1.1 V vs. RHE. - The NH3 yield and Faraday efficiency of the synthesis of NH3 are shown in the following results. Figure 7 As shown. By Figure 7 It can be seen that Cu2O electrocatalyzes NO2 - When it has >50mg h -1 mg cat -2NH3yield of 71.1 mg h-1mg-1and a Faradaic efficiency of 92%. The electrocatalytic NO2 - performance was greatly improved (NH3yield > 71.1 mg h -1 mg cat -2 mg-1mg-1and a Faradaic efficiency > 96%).

[0145] It should be noted that, although the technical solutions of the present application are described with specific examples, those skilled in the art can understand that the present application should not be limited thereto.

[0146] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A method for the preparation of a dual-site Cu-based catalyst for the electrocatalytic reduction of nitrogenous pollutants / N2O to ammonia, characterized in that, The method comprises the following steps: S1: dissolving polymeric carbon in an organic solvent to obtain a mixed solution A, and immersing Cu2O catalyst in the mixed solution A to obtain a mixed solution B, and heating the mixed solution B to volatilize the organic solvent to obtain polymeric carbon / Cu2O powder; wherein the amount of the polymeric carbon is 1%-10% of the mass of the Cu2O catalyst; the polymeric carbon comprises carbon atom clusters with a carbon atom number of 20-100; S2: grinding the polymeric carbon / Cu2O powder, annealing in an inert atmosphere, and obtaining polymeric carbon / Cu2O catalyst after cooling.

2. The preparation method according to claim 1, characterized in that: the organic solvent comprises one or more of benzene, toluene, cumene, bromoform, m-xylene, chlorobenzene, 1,2,3-tribromopropane, carbon disulfide, tetralin, 1,2,4-trichlorobenzene, 1,2-dichlorobenzene, 1-methylnaphthalene, and 1-chloronaphthalene; and / or, the concentration of the polymeric carbon in the mixed solution A is 3.5 g / L or less.

3. The production method according to claim 1 or 2, characterized by, In step S1, the dissolving is performed by ultrasonic dissolution, and the ultrasonic dissolution is performed for 15 min-60 min; the immersing is performed by ultrasonic immersing, and the ultrasonic immersing is performed for 15 min-60 min; the heating is performed at a temperature of 50°C-80°C.

4. The production method according to claim 1 or 2, characterized by, In step S2, the inert gas used in the inert atmosphere comprises one or more of nitrogen, argon, and helium; in the annealing step, the temperature is raised at a rate of 1-5°C / min, and the annealing temperature is 150-350°C.

5. The production method according to claim 1 or 2, characterized by, The preparation of the Cu2O catalyst comprises the following steps: (1) dissolving Cu precursor salt in ultrapure water to obtain a Cu precursor salt solution; (2) dissolving NaOH in ultrapure water to obtain a NaOH solution; (3) slowly adding the NaOH solution to the Cu precursor salt solution, stirring until mixed uniformly, then adding D-(+)-glucose, and heating, followed by filtering, washing, and drying to obtain the Cu2O catalyst.

6. The preparation method according to claim 5, characterized in that, The Cu precursor salt comprises one or more of copper nitrate, copper nitrate trihydrate, copper sulfate, copper sulfate pentahydrate, copper chloride, copper chloride dihydrate, copper acetate, or copper acetate monohydrate; and / or, The resistivity of the ultrapure water is 18.2 MW cm; and / or, the molar concentration of the Cu precursor salt solution is 0.03-0.1 mol / L; and / or, the molar concentration of the NaOH solution is 0.5-2 mol / L; and / or, the amount of ultrapure water used in the NaOH solution is 0.5-0.7 times the amount of ultrapure water used in the Cu precursor salt solution; and / or, the amount of D-(+)-glucose added is 0.15-0.25 g per 1 mmol of Cu precursor salt; and / or, the heating is performed at a temperature of 50-70°C for 2-4 h.

7. A bi-site Cu-based catalyst prepared according to the process of any one of claims 1 to 6, said bi-site Cu-based catalyst having Cu 0 -Cu 1+ asymmetric sites.

8. A method for the electrocatalytic reduction of nitrogenous pollutants / N20 to ammonia, characterized in that, The method comprises the following steps: (I) mixing a second organic solvent, ultrapure water, a Nafion solution, and the polymeric carbon / Cu2O catalyst prepared by the preparation method according to any one of claims 1-6, and coating the mixture on the surface of carbon paper or carbon cloth, and drying to obtain a working electrode. (II) inserting the working electrode, the counter electrode and the reference electrode into an electrolyte solution to form an electrolytic cell, and synthesizing ammonia from the nitrogen-containing pollutants and / or N2O by an electrocatalytic method.

9. The method of claim 8, wherein, The nitrogen-containing pollutants include one or more of nitrate, nitrite, nitric oxide or nitrogen dioxide.

10. The method according to claim 8 or 9, characterized in that, The second organic solvent includes isopropyl alcohol or ethanol; and / or, The density of the polymeric carbon / Cu2O catalyst loaded on the working electrode is 0.5-1.5 mg / cm2 2 ; and / or, The potential of the working electrode is 0~-1.2 vs. RHE.

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