CN114481195A

CN114481195A - TiO2-MXene/IL modified electrode and its application in electrocatalysis of N2Conversion to NH3In (1)

Info

Publication number: CN114481195A
Application number: CN202210078093.4A
Authority: CN
Inventors: 宋溪明; 赵楠; 吴抒遥; 姜美娇; 章好迪; 陈奇男; 汪跃然; 张益祥
Original assignee: Liaoning University
Current assignee: Liaoning University
Priority date: 2022-01-24
Filing date: 2022-01-24
Publication date: 2022-05-13
Anticipated expiration: 2042-01-24
Also published as: CN114481195B

Abstract

The invention discloses TiO₂-MXene/IL modified electrode and its application in electrocatalysis of N₂Conversion to NH₃The use of (1). Adding TiO into the mixture₂Dissolving MXene in ionic liquid IL, and ultrasonic treating for 60min to obtain TiO₂-MXene/IL composite; taking TiO₂-MXene/IL composite material, coating on the surface of hydrophobic carbon cloth, standing at room temperature for 10min to make the material fully combine with the surface of hydrophobic carbon cloth to obtain TiO₂-MXene/IL modified electrode. TiO of the invention₂the-MXene/IL modified electrode is simple to prepare, shows excellent activity on electrocatalytic nitrogen reduction and has higher ammonia production rate and Faraday rate.

Description

TiO2-MXene/IL modified electrode and its application in electrocatalysis of N2Conversion to NH3In (1)

Technical Field

The invention belongs to the field of electrochemical catalytic nitrogen reduction, and particularly relates to TiO₂-MXene/IL modified electrode and its application in electrocatalytic nitrogen reduction.

Background

Ammonia is one of the chemical products with the largest yield in the world and plays an important role in the global economy. The ammonia is mainly derived from the traditional haber-bosch ammonia synthesis process: namely, high-purity nitrogen and hydrogen are converted into ammonia gas by using an iron-based catalyst under the conditions of high temperature and high pressure. The haber process for synthesizing ammonia has high energy consumption and serious pollution, the energy consumption of the whole process accounts for 1 percent of the total annual energy consumption of the world, the used high-purity hydrogen is derived from natural gas reforming of fossil fuel, and annual CO₂The discharge amount is up to 4.5 hundred million tons. Therefore, the method for synthesizing ammonia with environmental protection and low energy consumption is of great significance to sustainable development of national economy.

In recent years, the electrocatalytic nitrogen reduction for producing ammonia has attracted people's high attention, and related research reports show a rapid increase. However, current research shows that although the electrocatalytic technology can realize green synthesis of ammonia, at normal temperature and normal pressure, the electrocatalytic synthesis of ammonia has huge thermodynamic and kinetic obstacles due to extremely high stability of N ≡ N bond and slow adsorption of nitrogen, and the selectivity and ammonia production rate of Nitrogen Reduction Reaction (NRR) are greatly reduced due to the existence of hydrogen evolution competition reaction (HER). Therefore, how to increase the ammonia production rate and simultaneously increase the selectivity of the catalyst is the biggest challenge in the research of the electrocatalytic ammonia synthesis under normal temperature and pressure.

Disclosure of Invention

The invention aims to provide TiO with high electrocatalytic nitrogen reduction catalytic efficiency₂-MXene/IL modified electrode. The modified electrode shows excellent electrocatalytic activity for electrocatalytic nitrogen reduction, and the obtained Faraday efficiency and ammonia production rate are both high.

The purpose of the invention is realized by the following technical scheme: TiO 2₂-MXene/IL modified electrode, the preparation method comprises the following steps:

1)TiO₂-MXene/IL composite preparation: adding appropriate amount of TiO₂Adding MXene into ionic liquid IL, performing ultrasonic treatment for 60min, and mixing to obtain TiO₂-MXene/IL composites.

Preferably, the ionic liquid IL is 1-butyl 3-methylimidazolium hexafluorophosphate (BMIMPF)₆)。

Preferably, a suitable amount of TiO is added₂MXene was added to the ionic liquid IL to form a mixture at a concentration of 10 mg/mL.

2) Taking the TiO obtained in the step 1)₂-MXene/IL composite material, coating on the surface of hydrophobic carbon cloth electrode, standing at room temperature for 10min to make the composite material and hydrophobic carbon cloth surface fully combined to obtain TiO₂-MXene/IL modified electrode.

Further, the above TiO₂-MXene/IL modified electrode, said TiO₂The preparation method of the (E) -MXene comprises the following steps:

1) adding LiF into hydrochloric acid, and stirring for 20-30min to obtain an etchant; adding MAX powder into the etchant within 5min, and reacting at 30-40 deg.C for 24-36h to obtain mixture.

Preferably, the concentration of the hydrochloric acid is 9-12M.

2) And (2) centrifugally washing the mixture obtained in the step 1) by using deionized water, centrifuging at 3500rpm for 10min for each washing, removing the supernatant serving as waste after each washing, and repeating until the pH value of the supernatant is more than or equal to 5.

3) Adding an intercalation agent into the product obtained in the step 2), performing ultrasonic treatment for 60min, centrifuging at 10000rpm for 10min, and collecting the lower-layer precipitate; preferably, the intercalating agent is ethanol.

4) Adding deionized water into the precipitate obtained in the step 3), performing ultrasonic treatment for 20min, centrifuging at 3500rpm for 3min, collecting supernatant, and freeze-drying to obtain powdery MXene.

5) Putting the powdery MXene obtained in the step 4) into a muffle furnace, and calcining for 30min at 400 ℃ to obtain TiO₂-MXene。

The TiO provided by the invention₂-MXene/IL modified electrode in electrocatalysis of N₂Conversion to NH₃The use of (1).

Preferably, the method is as follows: with TiO₂the-MXene/IL modified electrode is a working electrode, the Ag/AgC1 electrode is a reference electrode, the platinum sheet is a counter electrode, and the molar ratio is 0.1MHCL is electrolyte, nitrogen is introduced into the electrolyte during experiment to enable the system to be in a nitrogen saturation state, and electrocatalysis N is carried out by utilizing a linear voltammetry scanning method and a chronoamperometry method₂Conversion to NH₃。

Preferably, in the linear voltammetry scanning method, the scanning sweep rate is 10mV s^-1In the chronoamperometry, the time taken for electrolysis is 8000 s.

The invention has the beneficial effects that:

1. TiO prepared by the invention₂-MXene/IL modified electrode having the general formula M₃C₂The MXene material adsorbs and activates N under mild conditions₂And promote N₂Conversion to NH₃. MXene nanoplatelets also exhibit p-N₂High adsorption capacity of the molecules. The MXene nanosheet has good conductivity, and the electron transfer rate can be improved in the NRR reaction process; with MXene nanosheet as TiO₂The support of (2) may be TiO₂The nano particles are uniformly dispersed on the surface, thereby avoiding TiO₂The spontaneous agglomeration of the catalyst is improved, the specific surface area of the catalyst is increased, and TiO on the surface₂Has rich oxygen vacancy, can effectively adsorb and activate nitrogen, thereby improving the nitrogen reduction catalytic efficiency

2. The invention adopts TiO₂Mixing MXene and hydrophobic ionic liquid, and constructing a hydrophobic protective layer on the surface of the catalyst by the hydrophobic ionic liquid to reduce H₂The transfer rate of O (proton donor), limiting the accessibility of its kinetics, and ultimately suppressing H₂Generating and improving NRR selectivity.

3. The invention controls the technical parameters in the catalysis process, and reasonably collocates the raw materials of the electrode material, thereby improving the efficiency of electrochemical electrocatalysis nitrogen reduction, and improving the ammonia production rate and Faraday efficiency. TiO of the invention₂The ammonia generating rate of the-MXene/IL modified electrode in the electrocatalytic nitrogen reduction process is 25.7 mu g h at the applied voltage of-0.125V (vs. RHE)^-1mg^-1 _catThe Faraday efficiency was 21.68%.

Drawings

FIG. 1 shows MAX (A), MXene (B) and TiO₂SEM topography of MXene (C) material.

FIG. 2A is the XRD patterns of MAX (a) and MXene (b).

FIG. 2B is TiO₂XRD patterns of MXene (a) and MXene (b).

FIG. 3A is TiO₂Raman plots of MXene (a) and MXene (b) (test range of 100-^-1)。

FIG. 3B is TiO₂Raman spectra of MXene (a) and MXene (b) (test range of 100-^-1)。

FIG. 4A shows UV-visible absorption spectrum curves of different ammonium chloride solutions of known concentration, with absorbance at 655nm corresponding to NH, using indophenol blue coloration₄ ⁺The concentration of (c).

FIG. 4B is a corresponding calibration curve for calculating NH in electrolyte₄ ⁺Concentration of ions (error bar SD, n 3).

FIG. 4C shows UV-visible absorption spectra curves of various hydrazine hydrate solutions of known concentration using the Watt-Chrisp method, where the absorbance at 455nm corresponds to the concentration of hydrazine hydrate.

Fig. 4D is the corresponding calibration curve used to calculate the concentration of hydrazine hydrate in the electrolyte (error bar SD, n 3).

FIG. 5A is TiO₂-MXene-IL/CC general N₂And LSV pattern by Ar.

FIG. 5B is TiO₂I-T diagram of-MXene-IL/CC undergoing 8000s of electrocatalytic nitrogen reduction at-0.025, -0.075, -0.125, -0.175, -0.225, -0.275V (vs. RHE), respectively.

Fig. 5C is an ultraviolet-visible absorption spectrum (V vs. rhe) of the electrolyte after NRR reaction at different potentials for 8000s and color development by the indigo method.

FIG. 5D is TiO₂Faraday efficiencies of MXene/IL/CC at different potentials.

FIG. 5E is TiO₂NH production by MXene/IL/CC at different potentials₃The rate.

FIG. 5F is the ultraviolet-visible absorption spectrum (V vs. RHE) of an electrolyte developed using Watt-Chrisp after NRR reaction at different potentials for 8000 s.

FIG. 6A is TiO₂-MXene/CC, IL/CC and CC at-0.125V (vs. RHE) in N₂Chronoamperometric profile of the electrocatalytic synthesis of ammonia from saturated 0.1M HCl.

FIG. 6B is TiO₂-MXene/IL/CC、TiO₂-MXene/CC, IL/CC and CC at-0.125V (vs. RHE) in N₂8000s ammonia production efficiency chart of saturated 0.1M HCl internal electrolysis.

FIG. 6C is TiO₂-MXene/IL/CC、TiO₂-MXene/CC, IL/CC and CC at-0.125V (vs. RHE) in N₂8000s faradaic efficiency plot of saturated 0.1M HCl internal electrolysis.

FIG. 7A is TiO₂I-t plots of 5 NRR cycling experiments at-0.125V (vs. RHE) for MXene/IL/CC.

FIG. 7B is TiO₂Faraday efficiency plot of 5 NRR cycles at-0.125V (vs. RHE) for MXene/IL/CC.

FIG. 7C is TiO₂Ammonia production efficiency plot of-MXene/IL/CC at-0.125V (vs. RHE) for 5 NRR cycles.

Detailed Description

Example 1 TiO₂-MXene/IL modified electrode

The preparation method comprises

1、TiO₂Preparation of (MXene)

1) 2g LiF was added to 40mL of 9M hydrochloric acid, and the mixture was continuously stirred for 30 minutes to obtain an etchant. 2g of MAX powder was gradually added to the above etchant over 5min and reacted at 35 ℃ for 24h to obtain a mixture.

2) Washing with deionized water: the mixture obtained in step 1) was washed several times with deionized water by centrifugation (3500rpm, 10min each). After each wash, the supernatant pH was measured until the supernatant pH was ≥ 5, the supernatant was removed as waste by decanting, and the lower precipitate was collected.

3) Ethanol ultrasonic treatment: adding ethanol into the precipitate obtained in step 2), performing ultrasonic treatment for 60min, centrifuging (10000rpm, 10min), removing the supernatant as waste by pouring, and collecting the lower precipitate.

4) Collecting MXene: adding deionized water into the precipitate obtained in the step 3), performing ultrasonic treatment for 20min, centrifuging at 3500rpm for 3min, observing dark green supernatant, collecting supernatant, and freeze drying to obtain powder MXene.

5)TiO₂-MXene preparation: putting the powdery MXene obtained in the step 4) into a muffle furnace, and calcining for 30min at 400 ℃ to obtain TiO₂-MXene。

2、TiO₂Preparation of (E) -MXene/IL composite material

Adding TiO into the mixture₂-MXene added to hydrophobic ionic liquid BMIMPF₆(1-butyl 3-methylimidazolium hexafluorophosphate) to form a mixed solution with the concentration of 10mg/mL, ultrasonically oscillating for 60min, and fully mixing to obtain TiO₂-MXene/IL composite.

3. Pretreatment of electrodes

Cutting hydrophobic carbon cloth to 0.5 × 1.5cm²Size.

4、TiO₂Preparation of-MXene/IL modified electrode

Taking the TiO obtained in the step 2₂-MXene/IL composite material, coating on the surface of hydrophobic carbon cloth, standing at room temperature for 10min to make the composite material and carbon cloth surface fully combined to obtain TiO₂-MXene/IL modified electrode.

(II) detection

FIG. 1 shows MAX (A), MXene (B) and TiO₂SEM topography for the-MXene (C) material, as seen from A in FIG. 1, the MAX phase is a monolithic block. And MXene (B in figure 1) obtained after etching forms an accordion-like structure. After oxidation treatment, TiO is obtained₂Scanning electron micrograph of MXene As shown in FIG. 1C, it can be seen that the structure of MXene has remained, but the surface has a compact TiO layer₂And (4) generating particles.

FIG. 2A is the XRD patterns of MAX (a) and MXene (b). FIG. 2B is TiO₂XRD patterns of MXene (a) and MXene (b). As can be seen from fig. 2A, the characteristic peak of (002) of MXene (b) is shifted to the left relative to max (a), indicating that the MXene interlamellar spacing is large, thereby indicating the successful synthesis of MXene nanomaterials. And TiO obtained after MXene is oxidized₂MXene, FIG. 2B, where the (002) peak of MXene was retained and the remaining peak was anatase TiO₂Except for MXene and TiO₂No other peak was observed, indicating that the material obtained after oxidation hadGood phase purity and crystal form.

FIG. 3A is TiO₂Raman plots of MXene (a) and MXene (b) (test range of 100-^-1). FIG. 3B is TiO₂Raman plots for MXene (a) and MXene (b) (test range 100-2000 cm)^-1). Two samples at about 260, 400 and 600cm as shown in FIG. 3B^-1All three peaks are shown, which can be totally attributed to MXene, indicating that MXene is not completely converted during oxidation. At the same time, the samples treated as in FIG. 3A were at 154cm^-1A new peak appears, indicating the formation of anatase, indicating the formation of TiO₂XRD and Raman show MXene and TiO₂Are co-existing, so the material can be defined as TiO₂-MXene。

Example 2 TiO₂-MXene/IL modified electrode in electrocatalysis of N₂Application in reduction

And (3) electrolytic product testing: the ammonia content is tested by adopting an indophenol blue method; the hydrazine content is measured by a Watt-Chrisp method; the content is measured and then the Faraday efficiency and the ammonia production rate are calculated.

The faraday efficiency calculation formula is FE% ═ 3F × n × V) × 100/(17 × Q);

wherein F is the Faraday constant and n is the NH produced₃Q is the amount of charge and V is the volume of the electrolyte.

The ammonia production rate is calculated by the formula V ═ n × V)/(T × m);

wherein n is the NH produced₃V is the volume of the electrolyte, T is the reaction time, and m is the catalyst mass.

The method comprises the following steps: with TiO as a carrier₂The method comprises the following steps of taking an MXene/IL modified electrode as a working electrode, an Ag/AgC1 electrode as a reference electrode, a platinum sheet as a counter electrode, taking 0.1M HCL as electrolyte, placing a three-electrode system in 0.1M HCL, selecting a CHI760e electrochemical workstation for electrochemical measurement, judging whether the system can generate nitrogen reduction and the voltage range of the nitrogen reduction by using a linear voltammetry scanning method, and electrolyzing by using a chronoamperometry to convert nitrogen into ammonia. Before carrying out electrochemical test, N is firstly switched on₂And (5) gas is used for 30min to ensure the corresponding gas saturation state of the electrolyte. Measuring the electrolyzed solution by ultravioletThe ammonia production rate and the faraday efficiency were calculated by calculating the solubility of ammonia from the measured standard curve. The potentials are all converted into the potentials based on the reversible hydrogen electrode, according to the Nernst equation E_RHE＝E_Ag/AgCl+0.059pH+0.197V。

The working electrodes are selected respectively as follows:

1) TiO prepared in example 1₂-MXene/IL modified electrode, labelled TiO₂-MXene/IL/CC。

2) Hydrophobic carbon cloth is a working electrode and is marked as CC.

3)TiO₂-MXene modified electrode: mixing TiO with₂Dissolving MXene in deionized water containing 0.5% naphthol to obtain 10mg/mL solution, placing 20 μ L of the solution on hydrophobic carbon cloth surface, standing at room temperature for 10min, evaporating water to form TiO on electrode surface₂Thin film of MXene material to obtain TiO₂-MXene modified electrode, labelled TiO₂-MXene/CC。

4) Ionic liquid IL modified electrode: take 1uL BMIMPF₆And placing the hydrophobic carbon cloth surface for 20min to ensure that the ionic liquid is fully contacted with the carbon cloth surface to obtain an ionic liquid IL modified electrode which is marked as IL/CC.

(mono) TiO₂-MXene/IL/CC electrocatalytic nitrogen reduction

Prior to electrocatalytic nitrogen reduction, the ammonia standard curve was first determined using indophenol blue method on an ammonia standard solution and the Watt-christ method on the side product hydrazine that may be present. The measurement results are shown in FIGS. 4A to 4D.

30mL of a solution containing 0.1M HCl was placed in a single cell. Using a three-electrode system, using an Ag/AgC1 electrode as a reference electrode, a platinum sheet as a counter electrode, and a working electrode made of TiO₂MXene/IL/CC, N-cut before electrochemical testing₂Gas was allowed for 30min to ensure saturation of the respective gases. Electrochemical measurement adopts CHI760e electrochemical workstation, and performs timed amperometric electrolysis for 8000s, with the test results shown in FIGS. 5A-5F.

FIG. 5A is TiO₂-MXene/IL/CC passing N₂And LSV pattern by Ar. From FIG. 5A, TiO can be seen₂-MXene/IL/CC modifying electrodeElectrocatalytic nitrogen reduction reactions can occur, both at-0.3 to 0V (vs. rhe). FIG. 5B is TiO₂I-T diagram for 8000s electrocatalytic nitrogen reduction at-0.025, -0.075, -0.125, -0.175, -0.225, -0.275V (vs. RHE), respectively, MXene/IL/CC. FIG. 5C shows UV-visible absorption spectrum measurements of the electrolyte after NRR reaction at different potentials for 8000s and subsequent development of the electrolyte by the indigo method. According to the ultraviolet peak at 655nm of the electrolyte at different potentials and the measured standard curve of ammonia, the concentration of the electrolytic liquid ammonia at different potentials can be obtained, and then according to a Faraday efficiency formula and an ammonia production rate formula, the Faraday efficiency (figure 5D) and the ammonia production rate (figure 5E) at different potentials can be calculated. According to the results, the highest faradaic efficiency and ammonia production rate of 21.68% and 25.7 mu g h at-0.125V (vs. RHE), respectively^-1mg^-1 _cat. The content of hydrazine which is a byproduct of the electrolyte after electrolysis at different potentials is also measured by ultraviolet absorption, and as can be seen from figure 5F, the ultraviolet absorption peak of hydrazine at different potentials is almost zero, which indicates that no byproduct is generated, and TiO is₂The selectivity of the-MXene/IL/CC modified electrode is better.

(di) TiO₂-MXene/IL/CC、TiO₂-MXene/CC, IL/CC and CC at-0.125V (vs. RHE) in N₂Electrocatalytic ammonia synthesis performance of saturated 0.1M HCl

Using a three-electrode system, using Ag/AgC1 electrode as reference electrode, platinum sheet as counter electrode, and TiO as working electrode₂-MXene/IL/CC、TiO₂MXene/CC, IL/CC and CC, electrochemical determination is carried out by using CHI760e electrochemical workstation at-0.125V (vs. RHE) under N₂The saturated 0.1M HCl electrocatalytic synthesis of ammonia, the results are shown in FIGS. 6A-6C.

FIG. 6A shows different modified electrodes at-0.125V (vs. RHE) under N₂Chronoamperometric profile of the electrocatalytic synthesis of ammonia from saturated 0.1M HCl. Different electrodes are subjected to NRR reaction at-0.125V (vs. RHE) for 8000s, then the electrolyte is subjected to color development by using an indigo method, and ultraviolet-visible absorption spectrum measurement is carried out to measure the ammonia concentration, so that the Faraday efficiencies (figure 6C) and the ammonia production rates (figure 6B) of the different electrodes are calculated, and as can be seen from figures 6A-6C, the electrodes are modified by using ionic liquid alone or carbon cloth alone, and the ammonia production rates and the Faraday rates are very highSmall and almost zero, which shows that the capability of synthesizing ammonia by electrocatalytic nitrogen reduction of pure ionic liquid and hydrophobic carbon cloth is very low, and TiO is used₂MXene is dissolved in water to modify the electrode, has certain electrocatalysis capacity, but the faradaic efficiency and the ammonia production rate are less than those of the electrode dissolved in the ionic liquid. In conclusion, the hydrophobic ionic liquid forms a hydrophobic protective layer on the surface of the catalyst, so that water molecules can be greatly reduced to the surface of the catalyst, nitrogen is more contacted with the surface of the catalyst, and the competition of hydrogen evolution reaction is reduced, thereby improving the efficiency of synthesizing ammonia by electrocatalytic nitrogen reduction.

(III) TiO₂Study on electrocatalytic nitrogen reduction stability of (E) -MXene/IL modified electrode

Make TiO react₂-MXene/IL modified electrode at-0.125V (vs. RHE) under N₂The saturated 0.1M HCl is cycled for five times to carry out electro-catalysis synthesis on ammonia so as to judge the stability of the electrode, and the test result is shown in figures 7A-7C, the ammonia production rate is almost unchanged when the electrode is cycled for five times, but the Faraday efficiency is reduced for the fifth time, and the ionic liquid is probably dropped off, but the catalyst has certain stability overall.

Claims

1.TiO₂-MXene/IL modified electrode, characterized in that the preparation method comprises the following steps:

1)TiO₂-MXene/IL composite preparation: adding appropriate amount of TiO₂Adding MXene into ionic liquid IL, performing ultrasonic treatment for 60min, and mixing to obtain TiO₂-MXene/IL composite;

2) taking the TiO obtained in the step 1)₂-MXene/IL composite material, coating on the surface of carbon cloth electrode, standing at room temperature for 10min to obtain TiO₂-MXene/IL modified electrode.

2. The TiO of claim 1₂-MXene/IL modified electrode, characterized in that said TiO is₂The preparation method of the (E) -MXene comprises the following steps:

1) adding LiF into hydrochloric acid, and stirring for 20-30min to obtain an etchant; gradually adding MAX powder into the etchant within 5min, and reacting at 30-40 deg.C for 24-36h to obtain a mixture;

2) centrifuging and washing the mixture obtained in the step 1) by using deionized water, centrifuging for 10min at 3500rpm for each washing, removing the supernatant serving as waste after each washing, and repeating until the pH value of the supernatant is more than or equal to 5;

3) adding an intercalation agent into the product obtained in the step 2), performing ultrasonic treatment for 60min, centrifuging at 10000rpm for 10min, and collecting the lower-layer precipitate;

4) adding deionized water into the precipitate obtained in the step 3), performing ultrasonic treatment for 20min, centrifuging at 3500rpm for 3min, collecting supernatant, and freeze-drying to obtain powdery MXene;

3. The TiO of claim 2₂-MXene/IL modified electrode, characterized in that in step 1) said hydrochloric acid has a concentration of 9-12M.

4. The TiO of claim 2₂-MXene/IL modified electrode, characterized in that in step 3) said intercalating agent is ethanol.

5. The TiO of claim 1₂-MXene/IL modified electrode, characterized in that in step 1) said ionic liquid IL is 1-butyl 3-methylimidazolium hexafluorophosphate.

6. The TiO of claim 1₂-MXene/IL modified electrode, characterized in that in step 1), a suitable amount of TiO is added₂MXene was added to the ionic liquid IL to form a mixture at a concentration of 10 mg/mL.

7. The TiO of any one of claims 1 to 6₂-MXene/IL modified electrode in electrocatalysis of N₂Conversion to NH₃The use of (1).

8. Use according to claim 7, characterized in that the method is as follows: the method as claimed in any one of claims 1 to 6The above TiO₂the-MXene/IL modified electrode is a working electrode, the Ag/AgC1 electrode is a reference electrode, the platinum sheet is a counter electrode, 0.1M HCL is electrolyte, nitrogen is introduced into the system, and electrocatalysis is carried out on N by utilizing a linear voltammetry scanning method and a chronoamperometry method₂Conversion to NH₃。

9. The use according to claim 8, wherein in the linear voltammetry scan, the scan rate is 10mV s^-1In the chronoamperometry, the time taken for electrolysis is 8000 s.