A catalytic material for electrocatalytic reduction of NO, and a preparation method and application thereof

Abstract

The application provides a preparation method of a catalytic material for electrocatalytic NO reduction, comprising the following steps: S1, providing a mixed powder of sodium salt and potassium salt; S2, mixing the mixed powder, a transition metal source and a boron source to obtain a powder to be calcined; S3, calcining the powder to be calcined at a temperature of 650-1050 DEG C for 90-180 min to obtain the catalytic material; wherein the calcining is carried out under the protection of a protective atmosphere. The prepared catalyst has great superiority when applied to the field of electrocatalytic reduction of NO to produce ammonia.

Description

Technical Field

[0001] This invention relates to the electrocatalytic reduction of NO, and more particularly to a catalytic material for the electrocatalytic reduction of NO, its preparation method, and its application. Background Technology

[0002] Ammonia (NH3) is crucial to the global economy. Firstly, with the explosive growth of the global population, naturally occurring NH3 is insufficient to support agricultural production worldwide. Secondly, ammonia offers significant advantages in energy storage and transportation, making it a highly promising liquid fuel and hydrogen storage molecule. Currently, the mainstream ammonia production process is the Haber-Bosch process; however, this process is expensive, consumes enormous amounts of energy, and has a significant negative impact on global energy consumption and carbon footprint.

[0003] Currently, the electrocatalytic reduction of NO to ammonia has attracted widespread attention. This method, while correcting the imbalance in the nitrogen cycle, produces high-value ammonia nitrogen at low cost, forming a novel and meaningful artificial catalytic nitrogen cycle process. The search for highly efficient transition metal-based electrocatalysts is of great significance for accelerating the global promotion of electrocatalytic NO reduction to ammonia.

[0004] In existing technologies, Co, Ni, and Fe-based catalysts have attracted widespread attention and are seen as promising alternatives to noble metal electrocatalysts. However, when specifically applied to the electrocatalytic reduction of NO, the electrocatalytic efficiency of Co, Ni, and Fe for NO is not ideal.

[0005] Therefore, it is necessary to propose a catalytic material for the electrocatalytic reduction of NO, its preparation method and application, in order to solve or alleviate the above-mentioned technical defects of low electrocatalytic activity for NO. Summary of the Invention

[0006] The main objective of this invention is to provide a catalytic material for the electrocatalytic reduction of NO, its preparation method, and its application, aiming to solve the aforementioned technical problem of low electrocatalytic activity for NO.

[0007] To achieve the above objectives, the present invention provides a method for preparing a catalytic material for electrocatalytic NO reduction, comprising the following steps:

[0008] S1 provides a mixed powder of sodium and potassium salts;

[0009] S2, the mixed powder, transition metal source and boron source are mixed to obtain the powder to be calcined;

[0010] The mass ratio of the mixed powder to the transition metal source and the boron source is 1 to 20:1.

[0011] The molar ratio of the transition metal in the transition metal source to the boron in the boron source is 1:1 to 8;

[0012] S3, the powder to be calcined is calcined at a temperature of 650-1050°C for 90-180 min to obtain the catalyst material; wherein the calcination is carried out under a protective atmosphere.

[0013] Furthermore, the molar ratio of the sodium salt to the potassium salt is 1:1 to 3.

[0014] Further, the sodium salt includes sodium chloride; the potassium salt includes potassium chloride; the transition metal source includes one or more transition metal oxides and transition metals; and the boron source includes one or more boron and boron compounds.

[0015] Furthermore, the transition metal in the transition metal source includes one or more of Fe, Co, and Ni.

[0016] The present invention also provides a catalytic material for electrocatalytic NO reduction, which is prepared by any of the preparation methods described above.

[0017] The present invention also provides the application of any of the catalytic materials described above in the electrocatalytic reduction of NO.

[0018] The present invention also provides an electrode for electrocatalytic NO reduction, wherein the active material in the electrode comprises any of the catalytic materials described above.

[0019] The present invention also provides an electrocatalytic device, wherein the electrocatalytic device is provided with any of the electrodes described above.

[0020] The present invention also provides a method for electrocatalytic reduction of NO, wherein the electrode as described above is used as the cathode of the electrocatalytic device; and during the electrocatalytic process, NO is introduced into the cathode chamber of the electrocatalytic device.

[0021] Furthermore, the electrolyte in the cathode chamber contains sodium sulfate.

[0022] Compared with the prior art, the present invention has at least the following advantages:

[0023] This invention provides a catalytic material for the electrocatalytic reduction of NO, which exhibits high catalytic activity for NO electrocatalysis, thereby achieving efficient activation of NO molecules and improving the ability and efficiency of electrocatalytically converting NO to NH3. Specifically, this invention introduces the non-metallic element boron. The introduction of boron into the catalyst has a positive effect on the regulation of the material's electronic structure, enhancing charge transfer capability and greatly improving the adsorption performance of NO on the catalytic material surface. This enables the green and efficient production of ammonia. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 The image shows the XRD pattern of CoB-4 in Embodiment 1 of this invention.

[0026] Figure 2 This is the XRD pattern of CoB-2 in Embodiment 2 of the present invention;

[0027] Figure 3 This is the XRD pattern of CoB-8 in Embodiment 3 of the present invention;

[0028] Figure 4 This is a comparison of the full XPS photoelectron spectroscopy (XPS) spectra of Co, CoB-2, CoB-4, and CoB-8 in this invention;

[0029] Figure 5 The XPS photoelectron spectroscopy (XPS) boron fine spectra (B 1s orbitals) of CoB-2, CoB-4, and CoB-8 in this invention are shown.

[0030] Figure 6 This is a comparison chart of the NO adsorption capacities of Co, CoB-2, CoB-4, and CoB-8 in Example 4 of the present invention;

[0031] Figure 7 The polarization curves (LSV) of Co and CoB-4 in Ar and NO saturated 0.5M Na2SO4 electrolytes in Example 5 of the present invention are shown.

[0032] Figure 8 In Embodiment 6 of the present invention, Co, CoB-2, CoB-4, and CoB-8 are at -0.6V. RHE Ammonia production and ammonia Faraday efficiency under the given conditions;

[0033] Figure 9 The graph shows the ammonia production and ammonia Faraday efficiency of CoB-4 under different voltages in Example 6 of this invention.

[0034] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0037] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0038] To obtain a material with high catalytic activity for NO, this invention provides a method for preparing a catalytic material for electrocatalytic NO reduction, comprising the following steps:

[0039] S1, providing a mixed powder of sodium and potassium salts; that is: weighing sodium and potassium salts, grinding and mixing them evenly to obtain the mixed powder.

[0040] The molar ratio of the sodium salt to the potassium salt can be 1:1 to 3; the sodium salt may include or be sodium chloride; the potassium salt may include or be potassium chloride.

[0041] S2, the mixed powder, transition metal source, and boron source are mixed to obtain the powder to be calcined. The mixing process may include, or may involve, grinding the mixed powder, transition metal source, and boron source together.

[0042] In this invention, the mass ratio of (the mixed powder): (the sum of the transition metal source and the boron source) is 1 to 20:1, preferably 1 to 10:1; the molar ratio of (the transition metal in the transition metal source): (the boron in the boron source) is 1:1 to 8, preferably 1:3 to 5.

[0043] The transition metal source may include or be one or more of transition metal oxides and transition metals; the transition metal oxides and transition metals referred to in the transition metal source may include or be one or more of Fe, Co, and Ni, that is, the transition metal in the transition metal source may include or be one or more of Fe, Co, and Ni, specifically Co (cobalt); the boron source may include or be one or more of boron and boron-like compounds; when the boron source includes or is a boron-like compound (such as boron oxide), a reducing agent such as carbon may be introduced to participate in the reaction. Specifically, the transition metal source may include Co3O4, and the boron source may include boron powder.

[0044] S3, the powder to be calcined is calcined at a temperature of 650-1050°C for 90-180 min to obtain the catalytic material; further, the calcined product can be subjected to ultrasonic treatment, water washing treatment, ethanol washing treatment, drying treatment and grinding treatment in sequence to obtain the catalytic material, wherein the ultrasonic treatment can be carried out in water.

[0045] The calcination is carried out under a protective atmosphere, and the heating rate of the calcination can be 5 to 20 °C / min. During the calcination process, the flow rate of the protective atmosphere can be 60 to 100 mL / min.

[0046] It should be noted that Co, Ni, and Fe-based catalysts have attracted widespread attention and are seen as potential alternatives to noble metal electrocatalysts because these transition metals possess tunable 3d electronic structures, spin states, diverse crystal and electronic structures, and are extremely abundant in nature.

[0047] However, the performance of transition metal electrocatalysis for the reduction of NO to ammonia still has certain limitations. The main reasons are twofold: first, the low reactivity of NO. The low concentration of NO in the aqueous electrolyte severely limits the affinity of the electrode material for NO; second, low selectivity. This is primarily attributed to the ease with which hydrogen evolution reaction occurs in aqueous solutions of transition metal electrodes.

[0048] The nonmetallic element boron is unique in its electron-deficient and Lewis acid behavior, B-sp 3 Hybrid orbitals can accept lone pairs and feedback electrons from NO, but inherently have poor hydrogen adsorption capacity. They can selectively adsorb NO, thereby enhancing NO adsorption. Based on this, this invention proposes a strategy of electron-deficient boron alloying to enhance NO adsorption at transition metal interfaces, thereby improving the electrocatalytic efficiency of NO.

[0049] Furthermore, through experimental research, it has been found that the technical effect produced by the combination of non-metallic element boron with transition metal elements does not completely depend on the amount of boron. That is, the present invention is not a simple superposition of boron and cobalt.

[0050] Based on the above preparation method, the present invention provides a catalytic material for electrocatalytic NO reduction prepared by the preparation method described in any of the above embodiments.

[0051] Because the catalytic material possesses excellent electrocatalytic NO reduction performance, this invention also provides an application of the catalytic material as described in any of the above embodiments in electrocatalytic NO reduction. The product of the electrocatalytic NO reduction includes or may be ammonia (NH3); that is, NO is converted into NH3 through electrocatalytic reduction.

[0052] To facilitate electrocatalysis, this invention also provides an electrode for the electrocatalytic reduction of NO, characterized in that the active material in the electrode comprises a carbon composite material as described in any of the above embodiments. During the electrode preparation process, the carbon composite material can be loaded onto an electrode carrier.

[0053] The present invention also provides an electrocatalytic device for the electrocatalytic reduction of NO, wherein the electrocatalytic device is provided with electrodes as described in any of the above embodiments.

[0054] As one specific application of the catalytic material, the present invention also provides a method for electrocatalytic NO reduction, wherein the electrode as described in any of the above embodiments is used as the cathode of the electrocatalytic device; the electrocatalytic device typically has a proton exchange membrane to separate the anode chamber and the cathode chamber; during the electrocatalytic process, NO is introduced into the cathode chamber of the electrocatalytic device, wherein the electrolyte in the cathode chamber may contain sodium sulfate.

[0055] It should be noted that during the electrochemical detection of the test material in this invention, relevant conditions... As shown below:

[0056] Activation of proton exchange membrane (Nafion115): The proton exchange membrane was first soaked in deionized water for 1 hour, then soaked in 5% H2O2 for 1 hour, then soaked in deionized water for another 1 hour, then soaked in 0.5mol / L H2SO4 for 3 hours, and finally soaked in deionized water for 6 hours; the temperature during each soaking was 80℃.

[0057] Preparation of the working electrode (cathode): 40 μL of 5 wt% Nafion solution (perfluorosulfonic acid polymer solution) was added to 1 mL of anhydrous ethanol and mixed. Then, 5 mg of the test material was added to the anhydrous ethanol and ultrasonically mixed (30 kHz) for 2 h. 100 μL of the ultrasonically mixed liquid was then dropped onto a 1 × 1 cm plate. 2 The carbon paper surface (single-sided drop casting) is dried and then cut to 15mm*15mm to obtain the test electrode (working electrode) corresponding to the material to be tested.

[0058] Counter electrode and reference electrode: Electrochemical experiments were conducted using a CHI 660E electrochemical analyzer; a 15mm×15mm Pt sheet and an Ag / AgCl electrode (saturated KCl electrolyte) were used as the counter electrode and reference electrode, respectively, and electrochemical measurements were performed in an H-type cell with a three-electrode configuration.

[0059] Electrolyte: The electrolyte is a 0.5 mol / L Na2SO4 solution with a pH of 6.8; a new electrolyte was used for each of the multiple experiments.

[0060] Potential (voltage) calibration: The potential (voltage) described in this invention is calibrated using the formula E(vs.RHE)=E(vs.Ag / AgCl)+0.197+0.0592×pH; where pH is 6.8.

[0061] Test temperature: around 25℃.

[0062] The cathode chamber of the present invention has a gas inflow channel and a gas outflow channel to allow gas to be continuously introduced.

[0063] In the specific implementation of this invention, two glass bubblers containing 4 mol / L KOH solution can be used to eliminate potential NO2 contaminants in the introduced NO; after the test, Ar can be provided to the cathode assembly to remove unreacted NO gas.

[0064] To facilitate a detailed understanding of the present invention by those skilled in the art, the following examples are provided:

[0065] Example 1

[0066] Preparation of CoB-4:

[0067] Weigh 1.168 g (0.02 mol) of sodium chloride and 1.491 g (0.02 mol) of potassium chloride and place them in a mortar. Grind and mix for 30 min to obtain a mixed powder.

[0068] The above mixed powder was ground together with 0.4816g of transition metal source (Co3O4) and 0.2594g of boron source (B powder) for 30-60 minutes to obtain the powder to be calcined; wherein the atomic molar ratio of cobalt to boron is 1:4.

[0069] The powder to be calcined was calcined at 900℃ (heating rate 10℃ / min) for 120 min under an Ar atmosphere (flow rate 100 mL / min), and then naturally cooled to room temperature to obtain a solid sample.

[0070] The solid sample was placed in hot water at 80°C and sonicated (30 kHz) for 30 min. Then it was washed three times with deionized water and anhydrous ethanol, dried in a vacuum oven at 60°C, and ground for 30 min to obtain a catalytic material for electrocatalytic NO reduction (referred to as CoB-4 in this invention).

[0071] Example 2

[0072] Preparation of CoB-2:

[0073] Compared to Example 1, this embodiment only adjusts the atomic molar ratio of cobalt and boron to 1:2, that is, the amount of transition metal source added is 0.4816g and the amount of boron source added is 0.1297g, while other conditions remain unchanged, to obtain a catalytic material for electrocatalytic NO reduction (referred to as CoB-2 in this invention).

[0074] Example 3

[0075] Preparation of CoB-8:

[0076] Compared to Example 1, this embodiment only adjusts the atomic molar ratio of cobalt and boron to 1:8, that is, the amount of transition metal source added is 0.4816g and the amount of boron source added is 0.5188g, while other conditions remain unchanged, to obtain a catalytic material for electrocatalytic NO reduction (referred to as CoB-8 in this invention).

[0077] Analysis example 1

[0078] See Figure 1 As shown, it can be seen that only CoB is detected in CoB-4, and CoB in PDF card 03-0959 indicates that Co has been completely converted to CoB.

[0079] See Figure 2 As shown, CoB was not detected in CoB-2; only different types of Co were detected. This indicates that when the amount of B added is insufficient, cobalt oxide can only be reduced to cobalt, and CoB cannot be effectively formed.

[0080] See Figure 3 As shown, it can be seen that as the amount of B added further increases, only CoB is detected in CoB-8, indicating that Co is completely converted into CoB, and there may be a large amount of unconverted B.

[0081] See Figure 4 As shown, the content of B in Co, CoB-2, CoB-4, and CoB-8 increases step by step.

[0082] See Figure 5As shown, it can be seen that B mainly exists in the form of borate in CoB-2, while a large amount of unreacted B exists in CoB-8.

[0083] Example 4

[0084] Comparison of NO adsorption capacity:

[0085] The test materials in this embodiment are Co, CoB-2, CoB-4, and CoB-8, and the specific test procedure is as follows:

[0086] Weigh 100 mg of the test material and place it in a reaction tube. Pre-dry the material by increasing the temperature from room temperature to 100 °C at a programmed rate of 10 °C / min. Purge with a He gas flow (50 mL / min) for 1 h. Cool to 50 °C and introduce a mixture of NO gas for 1 h until saturation. Switch to a He gas flow (50 mL / min) and purge for 1 h to remove the weakly physically adsorbed NO on the surface. Finally, desorb the material by increasing the temperature to 700 °C at a rate of 10 °C / min under a He atmosphere. Detect the desorbed gas using a TCD.

[0087] Experimental results:

[0088] See Figure 6 As shown, it can be seen that: two boron-rich CoB-4 (5.60cm) 3 / g STP) and CoB-8 (5.21cm 3 / gSTP) catalyst compared to two boron-depleted Co (3.46cm) 3 / g STP) and CoB-2 (3.84cm 3 The / g STP catalyst exhibited a stronger NO adsorption capacity, indicating that boron plays a key role in significantly enhancing the intrinsic NO adsorption activity.

[0089] Example 5

[0090] Polarization curve comparison:

[0091] The test materials in this embodiment are Co and CoB-4, respectively; polarization curves of the test materials in Ar saturated electrolyte and NO saturated electrolyte were obtained in this embodiment.

[0092] The process of obtaining the polarization curve of the test material in an Ar-saturated electrolyte is as follows:

[0093] Argon gas was introduced into the electrolyte in the cathode chamber at a rate of 10 ml / min for 30 minutes to saturate the electrolyte with argon gas. Then, the polarization curve of the material under test was obtained under argon gas saturation.

[0094] The process of obtaining the polarization curve of the test material in a NO-saturated electrolyte is as follows:

[0095] Argon gas was introduced into the electrolyte in the cathode chamber at a rate of 10 ml / min for 30 minutes, followed by NO being introduced at a rate of 10 ml / min for 30 minutes to saturate the electrolyte with NO. The polarization curve of the test material was then obtained under NO saturation conditions.

[0096] Experimental results:

[0097] See Figure 7 As shown, it can be seen that from 0.2V RHE Initially, the LSV current of the Co electrode in NO-saturated electrolyte was higher than that in Ar-saturated electrolyte, indicating that Co has catalytic activity for eNORR.

[0098] Compared to Co, CoB-4 exhibits a larger current density in NO-saturated 0.5M Na2SO4 aqueous electrolyte and a smaller current density in Ar-saturated electrolyte, which means that eNORR is superior and the hydrogen evolution reaction (HER) is suppressed.

[0099] In both NO-saturated and Ar-saturated electrolytes, the more pronounced current density difference between the LSV curves indicates that more electrons are captured from NO; more NO adsorption sites allow more NO molecules to be reduced on the CoB surface, resulting in higher current density; the LSV results show that the introduction of boron improves the adsorption and activation performance of NO.

[0100] Example 6

[0101] Comparison of ammonia production and ammonia Faraday efficiency:

[0102] The test materials in this embodiment are Co, CoB-2, CoB-4, and CoB-8. Electrocatalytic experiments were conducted on the test materials to catalytically reduce NO to ammonia.

[0103] The specific experimental process is as follows:

[0104] After purging the electrolyte in the cathode chamber with argon gas at a rate of 10 ml / min for 30 minutes, NO was introduced at a rate of 10 ml / min for 30 minutes until the electrolyte reached NO saturation. Then, NO was continuously introduced at a rate of 10 ml / min, and the electrolysis reaction was carried out for one hour, completing the electrocatalytic experiment. In this embodiment, the ammonia content of the electrolyte after the electrocatalytic experiment was determined by Nanoparticle spectrophotometry.

[0105] This embodiment tested Co, CoB-2, CoB-4, and CoB-8 at -0.6V. RHE Ammonia yield and Faraday efficiency.

[0106] This embodiment also tested the ammonia yield and Faraday efficiency of CoB-4 at different voltages.

[0107] Experimental results:

[0108] See Figure 8 As shown, it can be seen that at -0.6V RHE Under the given conditions, Co, CoB-2, CoB-4, and CoB-8 each possessed a concentration of 134.3 μmol h⁻¹. -1 cm -2 154.2 μmol h -1 cm -2 262.9 μmol h -1 cm -2 64.4 μmol h -1 cm -2 The electrocatalytic ammonia production performance of NO.

[0109] It can also be seen that Co, CoB-2, CoB-4, and CoB-8 have ammonia faradaic efficiencies of 60.9%, 70.8%, 87.6%, and 70.4%, respectively.

[0110] See Figure 9 As shown, CoB-4 exhibits performance in the range of -0.2 to -0.8V. RHE Both exhibit good electrocatalytic ammonia production performance with NO, and -0.2V RHE -0.4V RHE -0.6V RHE -0.8V RHE The corresponding ammonia-faradaic efficiencies were 37.9%, 65.0%, 87.6%, and 62.2%, respectively.

[0111] Note: Figure 8 and Figure 9 In the diagram, the boxes with diagonal lines represent ammonia production, and the boxes with grayscale represent ammonia Faraday efficiency.

[0112] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. The application of a catalytic material in the electrocatalytic reduction of NO, characterized in that, The preparation method of the catalytic material includes the following steps: S1 provides a mixed powder of sodium and potassium salts; S2, the mixed powder, transition metal source and boron source are mixed to obtain the powder to be calcined; The transition metal in the transition metal source includes cobalt; The mass ratio of the mixed powder to the transition metal source and the boron source is 1~20:

1. The molar ratio of cobalt in the transition metal source to boron in the boron source is 1:4~8; S3, the powder to be calcined is calcined at a temperature of 650~1050℃ for 90~180min to obtain the catalyst material; wherein the calcination is carried out under a protective atmosphere.

2. The application according to claim 1, characterized in that, The molar ratio of the sodium salt to the potassium salt is 1:1 to 3.

3. The application according to claim 1, characterized in that, The sodium salt includes sodium chloride; the potassium salt includes potassium chloride; the transition metal source includes one or more transition metal oxides and transition metals; the boron source includes one or more boron and boron compounds.

4. A method for electrocatalytic reduction of NO, characterized in that, The electrode used for electrocatalytic NO reduction is used as the cathode of the electrocatalytic device; and NO is introduced into the cathode chamber of the electrocatalytic device during the electrocatalytic process. The active material in the electrode includes a catalytic material; The preparation method of the catalytic material includes the following steps: S1 provides a mixed powder of sodium and potassium salts; S2, the mixed powder, transition metal source and boron source are mixed to obtain the powder to be calcined; The transition metal in the transition metal source includes cobalt; The mass ratio of the mixed powder to the transition metal source and the boron source is 1~20:

1. The molar ratio of cobalt in the transition metal source to boron in the boron source is 1:4~8; S3, the powder to be calcined is calcined at a temperature of 650~1050℃ for 90~180min to obtain the catalyst material; wherein the calcination is carried out under a protective atmosphere.

5. The method for electrocatalytic NO reduction according to claim 4, characterized in that, The molar ratio of the sodium salt to the potassium salt is 1:1 to 3.

6. The method for electrocatalytic NO reduction according to claim 4, characterized in that, The sodium salt includes sodium chloride; the potassium salt includes potassium chloride; the transition metal source includes one or more transition metal oxides and transition metals; the boron source includes one or more boron and boron compounds.

7. The method for electrocatalytic NO reduction according to claim 4, characterized in that, The electrolyte in the cathode chamber contains sodium sulfate.

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