Pd4s / pveib / ppy / go nanomaterials, modified electrodes thereof and applications thereof

Abstract

The application belongs to the technical field of chemical synthesis, and particularly relates to Pd4S / PVEIB / PPy / GO nanomaterial, a modified electrode thereof and application. The Pd4S / PVEIB / PPy / GO nanomaterial is composed of poly-1-vinyl-3-ethyl imidazole bromide functionalized polypyrrole / graphene oxide carrier and Pd4S particles, and the core is Pd4S intermetallic sulfide phase. Air is used as a reaction gas, and electrochemical nitrogen oxide is used to prepare nitrate in an alkaline electrolyte. Experiments show that, at 1.77 V relative to a reversible hydrogen electrode, the yield and Faraday efficiency of nitrate in an air atmosphere are twice those in a nitrogen atmosphere, and are very stable. The material has mild preparation conditions, and provides a new technical route with high activity and high selectivity for direct air electrocatalytic synthesis of nitrate.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology, specifically relating to Pd4S / PVEIB / PPy / GO nanomaterials, their modified electrodes, and applications. Background Technology

[0002] Nitrates are essential basic chemical raw materials in modern agriculture, chemical industry, energy storage, and explosives. Currently, the industrial production of nitrates almost entirely relies on the traditional route of "Haber-Bosch process for ammonia synthesis + Ostwald process for catalytic oxidation." This route requires operation under high pressure and high temperature conditions, resulting in extremely high energy consumption and the emission of large amounts of carbon dioxide and nitrogen oxides. Therefore, developing a new green synthesis route for nitrates at ambient temperature and pressure with zero carbon emissions has become an urgent need in the field of sustainable development of the chemical industry.

[0003] In recent years, electrochemical nitrogen oxidation has attracted significant attention from both academia and industry as a promising green alternative. This method can directly oxidize nitrogen to nitrate using renewable electricity in an aqueous electrolysis system, offering significant advantages such as mild reaction conditions, compact process modules, zero carbon emissions, and easy coupling with distributed renewable energy sources like wind, solar, and tidal power. However, the technology is currently limited by bottlenecks such as the high activation energy of the N≡N triple bond, intense competitive oxygen evolution reaction, and low product selectivity. Faraday efficiency and nitrate yield are generally low, far from meeting the threshold for industrial application. The core scientific challenge in the field of electrocatalytic nitrogen oxidation lies in how to efficiently activate nitrogen under a mild anodic potential while simultaneously suppressing the oxygen evolution side reaction.

[0004] Of particular note is that lightning in nature can cause nitrogen and oxygen to react directly through high-voltage discharge to generate nitrogen oxides and eventually nitrates. This natural phenomenon provides an important inspiration for the electrochemical synthesis of nitrates using air as a direct gas source. Recent studies have also confirmed that introducing excess oxygen into the electrolyte can significantly enhance the efficiency of nitrogen oxidation reaction. Currently, there is a lack of electrocatalyst systems that can fully utilize the synergistic effect of oxygen in the air and possess both high catalytic activity and high product selectivity.

[0005] Therefore, developing a novel electrocatalyst that uses air as a direct gas source and can achieve high nitrate yield and high Faraday efficiency at low anode potential has significant academic value and application prospects. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing Pd4S / PVEIB / PPy / GO nanomaterials, their modified electrodes, and their applications.

[0007] The technical solution adopted in this invention is:

[0008] The preparation method of Pd4S / PVEIB / PPy / GO nanomaterials includes the following steps:

[0009] 1) Under ultrasonic conditions, pyrrole (Py) was chemically polymerized in situ onto GO nanosheets to obtain PPy / GO nanosheets;

[0010] 2) PPy / GO nanosheets were added to N,N-dimethylformamide and ultrasonically dispersed. Then allyl chloride and KOH were added and ultrasonically dispersed. The mixture was then transferred to an oil bath at 60°C and stirred for 24 hours. After centrifugation, washing, and vacuum drying, PPy / GO-CH2-CH=CH2 nanosheets were obtained.

[0011] 3) PPy / GO-CH2-CH=CH2 nanosheets were added to anhydrous ethanol and ultrasonically dispersed. Then, 1-vinyl-3-ethylimidazolium bromide and an initiator were added. The mixture was transferred to an oil bath at 80°C and refluxed for 5 hours. After the reaction was completed, the mixture was centrifuged, washed, and vacuum dried to obtain PVEIB / PPy / GO nanosheets.

[0012] 4) PVEIB / PPy / GO nanosheets were dispersed in N,N-dimethylformamide, and then bismuth reagent, trifluoroacetic acid and potassium chloropalladate were added in sequence and stirred evenly. The resulting reaction system was subjected to hydrothermal reaction. The product was washed with distilled water and anhydrous ethanol in sequence, centrifuged and vacuum dried to obtain Pd4S / PVEIB / PPy / GO nanomaterials.

[0013] Furthermore, in step 1) of the above-mentioned Pd4S / PVEIB / PPy / GO nanomaterials, the preparation method of the GO nanosheets is as follows: concentrated sulfuric acid, high-purity graphite and NaNO3 are added to a three-necked flask, stirred evenly, and the system temperature is kept below 5°C. KMnO4 is slowly and continuously added to the mixed solution over one hour, and then placed in a 36°C water bath for 0.5 hours. After standing at room temperature for two weeks, it is diluted with 60°C water, and H2O2 is added dropwise until the solution turns bright yellow. After centrifugation while hot and washing until neutral, it is vacuum dried to obtain GO nanosheets.

[0014] Furthermore, for the aforementioned Pd4S / PVEIB / PPy / GO nanomaterials, step 1) specifically involves: adding GO nanosheets to deionized water, ultrasonically dispersing them, then adding pyrrole (Py), continuing ultrasonic dispersion, adding FeCl3·6H2O, continuing ultrasonication, centrifuging and washing, and vacuum drying to obtain PPy / GO nanosheets.

[0015] Furthermore, in the aforementioned Pd4S / PVEIB / PPy / GO nanomaterials, step 3) uses azobisisobutyronitrile as the initiator.

[0016] Furthermore, in step 4) of the above-mentioned Pd4S / PVEIB / PPy / GO nanomaterials, the hydrothermal reaction is as follows: the obtained reaction system is placed in a Teflon reaction vessel with a polytetrafluoroethylene liner and hydrothermally reacted at 130°C for 12 hours.

[0017] A NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials is prepared by attaching any one of the above-mentioned Pd4S / PVEIB / PPy / GO nanomaterials onto a carbon cloth substrate.

[0018] Furthermore, the preparation method of the aforementioned NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials includes the following steps:

[0019] 1) Pd4S / PVEIB / PPy / GO nanomaterials were ultrasonically dispersed in a mixed solution of anhydrous ethanol and Nafion to obtain a uniformly dispersed composite modifier.

[0020] 2) The uniformly dispersed composite modifier was drop-coated onto a clean carbon cloth surface and dried at room temperature to obtain a NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials.

[0021] Furthermore, in the aforementioned NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials, in step 1), the volume ratio of anhydrous ethanol to Nafion is 46:4.

[0022] The above-mentioned application of a NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials in the electrocatalytic nitrogen oxidation synthesis of nitrate.

[0023] Furthermore, the above application is carried out as follows: using a NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials as the working electrode, an Hg / HgO electrode as the reference electrode, and a platinum sheet electrode as the auxiliary electrode to form a three-electrode system, and realizing the electrocatalytic nitrogen oxidation to synthesize nitrate in 0.1M potassium hydroxide solution.

[0024] The beneficial effects of this invention are:

[0025] 1. PVEIB / PPy / GO, as a conductive carrier, combines the excellent conductivity of polypyrrole, the high specific surface area of ​​graphene oxide, and the interfacial control capability of ionic liquid functional groups. This achieves high dispersion of intermetallic sulfide nanoparticles, significantly enhances electron transport efficiency, effectively suppresses competitive oxygen evolution side reactions, and improves the selectivity of the target product nitrate.

[0026] 2. This invention is the first to apply intermetallic sulfide Pd4S to the electrocatalytic nitrogen oxidation reaction. As an intermetallic compound phase with a definite stoichiometric ratio, Pd4S has palladium and sulfur atoms arranged in an ordered manner in the crystal lattice, which can provide uniform, stable and uniquely electronic catalytic active centers. It can effectively regulate the adsorption configuration and activation energy barrier of nitrogen molecules and oxygen-containing intermediates, and significantly reduce the rate-determining reaction energy barrier.

[0027] 3. This invention innovatively uses air directly as the reaction gas source to replace high-purity nitrogen. By utilizing the natural synergistic effect of oxygen in the air, the nitrate yield and Faraday efficiency are significantly improved at a lower anode potential. Compared with a pure nitrogen atmosphere, the nitrate yield under an air atmosphere can be increased several times, fundamentally breaking through the dependence of traditional electrochemical nitrogen oxidation on high-purity nitrogen.

[0028] 4. The modified electrode prepared by this invention exhibits excellent chemical stability and recyclability in long-term constant potential electrolysis tests, and has the potential for industrial application.

[0029] 5. The preparation process of this invention is simple and mild, the cost of the raw materials used is controllable, and it is easy to scale up production. Attached Figure Description

[0030] Figure 1 Scanning electron microscope (SEM) image (a) and transmission electron microscope (TEM) image (b) of Pd4S / PVEIB / PPy / GO nanomaterials.

[0031] Figure 2 XRD pattern (a) and energy dispersive spectroscopy (EDS) spectrum (b) of Pd4S / PVEIB / PPy / GO nanomaterials.

[0032] Figure 3 High-resolution transmission electron microscopy (HRTEM) images of Pd4S / PVEIB / PPy / GO nanomaterials.

[0033] Figure 4 LSV images of NOR electrocatalytically modified electrodes based on Pd4S / PVEIB / PPy / GO nanomaterials in saturated air, N2, and Ar, respectively.

[0034] Figure 5 Nitrate yield and Faradaic efficiency at 1.77 V (vs. RHE) under different conditions for CC (substrate) and NOR electrocatalytic modified electrodes based on Pd4S / PVEIB / PPy / GO nanomaterials.

[0035] Figure 6The nitrate yield and Faraday efficiency of the NOR electrocatalytically modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials at different voltages are shown.

[0036] Figure 7 The values ​​of nitrate yield and Faradaic efficiency of a NOR electrocatalytically modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials were obtained by catalyzing for two hours in ten consecutive cycles at the same voltage of 1.77V (vs. RHE). Detailed Implementation

[0037] Example 1: Pd4S / PVEIB / PPy / GO nanomaterials

[0038] (a) The preparation method is as follows:

[0039] 1) Preparation of GO nanosheets: 67.5 mL of concentrated sulfuric acid, 2.0 g of high-purity graphite, and 1.6 g of NaNO3 were added to a three-necked flask and stirred until homogeneous. The system temperature was kept below 5 °C. 9 g of KMnO4 was slowly and continuously added to the mixed solution over one hour, and then the mixture was placed in a 36 °C water bath for 0.5 h. After standing at room temperature for two weeks, the solution was diluted with 560 mL of 60 °C water, and H2O2 was added dropwise until the solution turned bright yellow. The solution was then centrifuged while hot (rpm = 10000), washed until neutral, and then vacuum dried at 50 °C to obtain GO nanosheets.

[0040] 2) PPy / GO nanosheets: Add 0.1g of GO nanosheets to 50mL of deionized water, disperse by ultrasonication, then add 0.1g of pyrrole (Py), disperse by ultrasonication again, then add 0.6g of FeCl3·6H2O, continue ultrasonication for 0.5h, centrifuge, wash and vacuum dry to obtain PPy / GO nanosheets.

[0041] 3) PPy / GO-CH2-CH=CH2 nanosheets: Add 0.03g of PPy / GO nanosheets to 50mL of N,N-dimethylformamide (DMF), disperse by ultrasonication, then add 0.3mL of allyl chloride (Cl-CH2-CH=CH2) and 0.1g of KOH, disperse by ultrasonication for 5min, transfer to an oil bath, stir and react at 60℃ for 24h, centrifuge, wash, and vacuum dry at 50℃ to obtain PPy / GO-CH2-CH=CH2 nanosheets.

[0042] 4) PVEIB / PPy / GO nanosheets: 0.025 g of PPy / GO-CH2-CH=CH2 nanosheets were added to 40 mL of anhydrous ethanol and ultrasonically dispersed. Then, 0.2 g of 1-vinyl-3-ethylimidazolium bromide (VEIB) and 0.004 g of azobisisobutyronitrile (AIBN) initiator were added, and the mixture was transferred to an oil bath and refluxed at 80 °C for 5 h. After the reaction was completed, the mixture was centrifuged, washed, and vacuum dried at 50 °C for 24 h to obtain PVEIB / PPy / GO nanosheets.

[0043] 5) Preparation of Pd4S / PVEIB / PPy / GO nanomaterials: First, 0.025g of PVEIB / PPy / GO nanosheets were dispersed in 4mL of N,N-dimethylformamide (DMF). Then, 0.01g of bismuth reagent (DMTD) was dissolved in 2mL of N,N-dimethylformamide (DMF), and 20μL of trifluoroacetic acid (TFA) was added. Next, 0.09g of potassium chloropalladium (K2PdCl6) was dissolved in 2mL of N,N-dimethylformamide (DMF). The three solutions were stirred evenly, and the resulting reaction system was transferred to a Teflon reactor with a polytetrafluoroethylene liner. The reaction was carried out hydrothermally at 130℃ for 12h. After the reaction was completed, the product was washed with distilled water and ethanol in sequence, centrifuged, and vacuum dried to obtain Pd4S / PVEIB / PPy / GO nanomaterials.

[0044] (II) Testing

[0045] 1. For example Figure 1 As shown, Figure 1 (a) is a scanning electron microscope (SEM) image of the Pd4S / PVEIB / PPy / GO nanomaterial; Figure 1 Image (b) is a transmission electron microscope (TEM) image of the Pd4S / PVEIB / PPy / GO nanomaterials. Figure 1 (a) As can be seen, the surface of the Pd4S / PVEIB / PPy / GO nanomaterials prepared in this invention exhibits a typical rough, layered structure. Figure 1 (b) Further, it is revealed that a large number of nanoparticles are uniformly and densely distributed on the surface of the sheet-like carrier without obvious aggregation, which ensures the efficient exposure of active sites.

[0046] 2. Figure 2 XRD pattern (a) and energy-dispersive X-ray spectroscopy (EDS) spectrum (b) of Pd4S / PVEIB / PPy / GO nanomaterials. Figure 2As can be seen, multiple distinct diffraction peaks appeared in the XRD pattern, with positions completely consistent with the standard reference line (JCPDS10-0335, Pd4S), further confirming the presence of Pd4S in the material and its good crystallinity. Energy dispersive spectroscopy analysis showed that the material mainly contains elements such as C, N, O, Pd, and S, with strong signals originating from Pd and S, consistent with the composition of the raw materials. This result confirms the successful loading of Pd4S at the elemental level, thus proving that the present invention successfully synthesized Pd4S / PVEIB / PPy / GO nanomaterials.

[0047] 3. Figure 3 High-resolution transmission electron microscopy (HRTEM) images of the Pd4S / PVEIB / PPy / GO nanomaterials are shown. The lattice fringes of the material are clearly displayed in the images. Two sets of interplanar spacings were measured and marked: d = 0.515 nm and d = 0.558 nm. These two spacing values ​​correspond to the (100) and (001) crystal planes of Pd4S, respectively, and are in high agreement with the JCPDS card (10-0335). This directly proves that the Pd4S crystalline phase was successfully synthesized, rather than pure metallic Pd or other morphologies.

[0048] Example 2: NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials

[0049] (a) The preparation method is as follows:

[0050] 1) Take 1.5 mg of Pd4S / PVEIB / PPy / GO nanomaterials prepared in Example 1, add 460 μL of anhydrous ethanol and 40 μL of Nafion solution, and sonicate for 30 min to obtain a black suspension with a concentration of 3 mg / mL, which is the composite modifier, for later use.

[0051] 2) Electrode preparation: Cut the carbon cloth into 1cm×1.5cm pieces for later use.

[0052] 3) Preparation of modified electrode: The composite modifier prepared in step 1) was repeatedly transferred using a dropper and applied to the surface of a clean carbon cloth. It was then allowed to air dry at room temperature to obtain a NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials.

[0053] (II) Electrochemical performance testing

[0054] 1. Comparison of linear sweep voltammetric curves of NOR electrocatalytic modified electrodes based on Pd4S / PVEIB / PPy / GO nanomaterials in saturated air, N2, and Ar.

[0055] Methods: In an electrolytic cell containing 0.1 M KOH solution, a NOR electrocatalytically modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials was used as the working electrode, an Hg / HgO electrode as the reference electrode, and a platinum sheet electrode as the auxiliary electrode. The experiment was conducted on a CHI1040c electrochemical workstation, with its accompanying computer software used for data acquisition and processing. Linear sweep voltammetry was performed in the potential range of 1.67 V to 2.17 V (vs. RHE), and stable linear sweep voltammetry diagrams were recorded.

[0056] like Figure 4 The figures show linear sweep voltammetry (LSV) comparisons of the NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials in saturated air, N2, and Ar. The upper curve is the LSV comparison under saturated air, the middle curve is the LSV comparison under saturated N2, and the lower curve is the LSV comparison under saturated Ar. In the potential range of 1.67V to 2.17V (vs. RHE), the current density under saturated air is significantly higher than that under saturated N2 and saturated Ar. This indicates that the prepared NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials has NOR activity, and the NOR activity under saturated air is significantly better than that under saturated N2 and saturated Ar conditions.

[0057] 2. Source of nitrogen in the electrocatalytic synthesis products of Pd4S / PVEIB / PPy / GO nanomaterials

[0058] A three-electrode system was constructed using a NOR electrocatalytically modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials as the working electrode, an Hg / HgO electrode as the reference electrode, and a platinum sheet electrode as the auxiliary electrode. Electrocatalytic nitrogen oxidation to nitrate was achieved in 0.1M KOH solution. The experiment was conducted on a CHI1040c electrochemical workstation, including the acquisition and processing of experimental data. Figure 5 The nitrate yield and Faradaic efficiency at 1.77V (vs. RHE) of carbon cloth (CC) and NOR electrocatalytically modified electrodes based on Pd4S / PVEIB / PPy / GO nanomaterials were compared under different conditions. To eliminate the influence of electrolyte, electrocatalyst, and feed gas on the NO3 production during electrolysis, [further details are needed]. - The interference was not detected by either the open-circuit voltage (O / C) of the air-saturated electrolyte or the 1.77V of the argon-saturated electrolyte. This indicates that the nitrogen in the nitrate generated under nitrogen or air-saturated electrolyte at 1.77V all comes from the electro-oxidation of nitrogen catalyzed by Pd4S / PVEIB / PPy / GO.

[0059] 3. Optimal catalytic voltage of NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials

[0060] The working electrode was a NOR electrocatalytically modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials, the reference electrode was a Hg / HgO electrode, and the auxiliary electrode was a platinum sheet electrode. The experiment was conducted on a CHI1040c electrochemical workstation, including the acquisition and processing of experimental data. In 0.1M KOH solution, the voltage value was taken at 0.1V intervals within the potential range of 1.67V to 2.17V (vs. RHE) for two hours of chronoamperometry. Figure 6 The nitrate yield and Faradaic efficiency of the NOR electrocatalytically modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials were compared at different voltages. At 1.77 V (vs. RHE), this material exhibited the best electrocatalytic nitrogen oxidation (NOR) performance. In nitrogen-saturated electrolyte, the nitrate yield was 25.09 μg h⁻¹. -1 mg -1 act The corresponding Faraday efficiency was 13.49%. When the reaction system was switched to saturated air and saturated electrolyte, the performance showed a significant leap, with the nitrate yield increasing to 53.13 μg h⁻¹. -1 mg -1 act The Faraday efficiency was also significantly improved to 31.69%. Compared with a nitrogen atmosphere, the yield under a saturated air atmosphere increased by approximately 2.12 times, and the Faraday efficiency increased by approximately 2.35 times. This result strongly indicates that the introduction of oxygen into the NOR system can significantly promote the formation of nitrates. Oxygen molecules play a key role in the reaction process, effectively improving the reaction rate and electron utilization efficiency. At the same time, the potential of 1.77V was determined to be the optimal operating voltage for this catalytic system.

[0061] 4. Stability measurement of catalysts

[0062] The working electrode was a NOR electrocatalytically modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials, the reference electrode was a Hg / HgO electrode, and the auxiliary electrode was a platinum sheet electrode. The experiment was carried out on a CHI1040c electrochemical workstation, including the acquisition and processing of experimental data. Ten chronoamperometry tests were performed continuously for two hours each in 0.1M KOH solution at a potential of 1.77V (vs. RHE). Figure 7The figures show the nitrate yield and Faradaic efficiency of the NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials after ten consecutive catalytic cycles for two hours at the same voltage. It can be seen that even after the tenth catalytic cycle, the nitrate yield and Faradaic efficiency still reached 95%, which proves that the prepared Pd4S / PVEIB / PPy / GO nanomaterials have excellent stability.

Claims

1. Pd4S / PVEIB / PPy / GO nanomaterials, characterized in that, Its preparation method includes the following steps: 1) Under ultrasonic conditions, pyrrole (Py) was chemically polymerized in situ onto GO nanosheets to obtain PPy / GO nanosheets; 2) PPy / GO nanosheets were added to N,N-dimethylformamide and ultrasonically dispersed. Then allyl chloride and KOH were added and ultrasonically dispersed. The mixture was then transferred to an oil bath at 60°C and stirred for 24 hours. After centrifugation, washing, and vacuum drying, PPy / GO-CH2-CH=CH2 nanosheets were obtained. 3) PPy / GO-CH2-CH=CH2 nanosheets were added to anhydrous ethanol and ultrasonically dispersed. Then, 1-vinyl-3-ethylimidazolium bromide and an initiator were added. The mixture was transferred to an oil bath at 80°C and refluxed for 5 hours. After the reaction was completed, the mixture was centrifuged, washed, and vacuum dried to obtain PVEIB / PPy / GO nanosheets. 4) PVEIB / PPy / GO nanosheets were dispersed in N,N-dimethylformamide, and then bismuth reagent, trifluoroacetic acid and potassium chloropalladate were added in sequence and stirred evenly. The resulting reaction system was subjected to hydrothermal reaction. The product was washed with distilled water and anhydrous ethanol in sequence, centrifuged and vacuum dried to obtain Pd4S / PVEIB / PPy / GO nanomaterials.

2. The Pd4S / PVEIB / PPy / GO nanomaterial according to claim 1, characterized in that, In step 1), the preparation method of the GO nanosheets is as follows: concentrated sulfuric acid, high-purity graphite and NaNO3 are added to a three-necked flask, stirred evenly, and the system temperature is kept below 5°C. KMnO4 is slowly and continuously added to the mixed solution over one hour, and then placed in a 36°C water bath for 0.5 hours. After standing at room temperature for two weeks, it is diluted with 60°C water, and H2O2 is added dropwise until the solution turns bright yellow. After centrifugation while hot and washing until neutral, it is vacuum dried to obtain GO nanosheets.

3. The Pd4S / PVEIB / PPy / GO nanomaterial according to claim 1, characterized in that, Step 1) specifically involves: adding GO nanosheets to deionized water, ultrasonically dispersing them, then adding pyrrole (Py), continuing ultrasonic dispersion, adding FeCl3·6H2O, continuing ultrasonication, centrifuging and washing, and vacuum drying to obtain PPy / GO nanosheets.

4. The Pd4S / PVEIB / PPy / GO nanomaterial according to claim 1, characterized in that, In step 3), the initiator is azobisisobutyronitrile.

5. The Pd4S / PVEIB / PPy / GO nanomaterial according to claim 1, characterized in that, In step 4), the hydrothermal reaction is as follows: the obtained reaction system is placed in a Teflon reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 130°C for 12 hours.

6. A NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials, characterized in that, The electrode is prepared by attaching the Pd4S / PVEIB / PPy / GO nanomaterials as described in any one of claims 1-5 onto a carbon cloth substrate.

7. The NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials according to claim 6, characterized in that, Its preparation method includes the following steps: 1) Pd4S / PVEIB / PPy / GO nanomaterials were ultrasonically dispersed in a mixed solution of anhydrous ethanol and Nafion to obtain a uniformly dispersed composite modifier. 2) The uniformly dispersed composite modifier was drop-coated onto a clean carbon cloth surface and dried at room temperature to obtain a NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials.

8. The NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials according to claim 7, characterized in that, In step 1), the volume ratio of anhydrous ethanol to Nafion is 46:

4.

9. The application of the NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials as described in claim 6 in the electrocatalytic nitrogen oxidation synthesis of nitrates.

10. The application according to claim 9, characterized in that, The method is as follows: A three-electrode system is formed by using a NOR electrocatalytic modified electrode based on Pd4S / PVEIB / PPy / GO nanomaterials as the working electrode, an Hg / HgO electrode as the reference electrode, and a platinum sheet electrode as the auxiliary electrode to achieve the electrocatalytic nitrogen oxidation to synthesize nitrate in 0.1M potassium hydroxide solution.

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