A La / La2O2S@rGO Mott-Schottky heterojunction material, its preparation method and application

Abstract

The present invention discloses a La / La₂O₂S@rGO Mott-Schottky heterojunction material, its preparation method and application; Preparation: S1. Ultrasonically disperse a lanthanum source, a sulfur source, potassium citrate and graphene oxide uniformly to obtain dispersion liquid A; S2. Heat and react dispersion liquid A to obtain a precursor; S3. Wash and dry the precursor; S4. Calcinate the precursor dried in step S3 at a high temperature under a protective atmosphere to obtain the La / La₂O₂S@rGO Mott-Schottky heterojunction material. The application of the La / La₂O₂S@rGO Mott-Schottky heterojunction material is characterized in that the La / La₂O₂S@rGO Mott-Schottky heterojunction material prepared by the above preparation method is used to fabricate an electrocatalytic material, and the electrocatalytic material is used for the oxygen reduction reaction and the oxygen evolution reaction to promote its application in a zinc-air battery. The preparation method of the present invention has the advantages of simple operation, low cost and easy regulation. When it is made into an electrocatalytic material and applied to the ORR and OER reactions, it can replace traditional expensive noble metal compound electrocatalysts.

Description

Technical Field

[0001] The present invention relates to the field of preparation of Mott - Schottky heterojunction materials, and particularly to a La / La2O2S@rGO Mott - Schottky heterojunction material, a preparation method thereof, and an application thereof. Background Art

[0002] The zinc - air battery is a new energy storage and conversion device. It has a high energy density, uses water as the electrolyte, has good environmental protection and high safety, and is expected to replace traditional lithium batteries. The zinc - air battery uses a zinc sheet as the negative electrode and air as the positive electrode, and reacts under the action of an electrocatalyst; during discharge, an oxygen reduction reaction (ORR) occurs, and during charging, an oxygen evolution reaction (OER) occurs. An electrocatalyst with both ORR and OER functions is called a bifunctional electrocatalyst. Currently, commercial bifunctional electrocatalysts are noble metal compounds, which are expensive and have poor stability.

[0003] The Mott - Schottky heterojunction is an interfacial region composed of a metal and a semiconductor. Due to the different work functions and Fermi levels of the metal and the semiconductor, electrons will spontaneously transfer from the one with a lower work function to the one with a higher work function. The orderly transfer of electrons at the interface is beneficial to improving the electrocatalytic performance. Constructing a heterojunction with rare - earth metal lanthanum and its oxysulfide semiconductor, using the active 4f electron structure of lanthanide metals, can hybridize with the s, p, d orbital symmetries to generate diverse electron energy levels. After hybridization, the 4f orbitals have a strong interaction with the conduction band of the semiconductor, causing electrons to transfer and redistribute. Due to the activity of the 4f orbitals of metal lanthanum, its work function and Fermi level are relatively low, and it is easy to form a Mott - Schottky heterojunction with its oxysulfide, and electrons are also easy to leave the metal. Summary of the Invention

[0004] The purpose of the present invention is to propose a preparation method of a low - cost La / La2O2S@rGO Mott - Schottky heterojunction material (electrocatalytic material) aiming at the problems of high price and poor stability of existing bifunctional electrocatalysts. This material has excellent electrocatalytic performance.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A preparation method of a La / La2O2S@rGO Mott - Schottky heterojunction material, characterized in that the method comprises the following steps:

[0007] S1. Ultrasonically disperse a lanthanum source, a sulfur source, potassium citrate, and graphene oxide uniformly to obtain dispersion liquid A;

[0008] S2. Heat - react the dispersion liquid A to obtain a precursor;

[0009] S3. Wash and dry the precursor;

[0010] S4. Calcinate the precursor dried in step S3 under a protective atmosphere to obtain the La / La2O2S@rGO Mott-Schottky heterojunction material.

[0011] Furthermore, a preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material: Step S1. Add a lanthanum source, a sulfur source, potassium citrate, and graphene oxide to deionized water, ultrasonically treat and stir evenly to obtain dispersion liquid A; wherein: the molar ratio between the lanthanum source, the sulfur source, the potassium citrate, and the graphene oxide is 1:(1 - 3):(1 - 2):10; the stirring rate is 1500 - 2000 rpm, and the stirring time is 20 - 40 minutes.

[0012] Furthermore, a preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material: The lanthanum source in step S1 is lanthanum nitrate; the sulfur source is L-cysteine.

[0013] Furthermore, a preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material: Step S2. Transfer the dispersion liquid A into a hydrothermal reaction kettle, and then place the hydrothermal reaction kettle in an oven and react at 150 - 230 °C for 8 - 10 hours to obtain a precursor.

[0014] Furthermore, a preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material: Step S3. Wash the precursor with water and ethanol respectively, and then dry it in an oven at 50 - 60 °C for 0.5 - 1 hour.

[0015] Furthermore, a preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material: The protective atmosphere in step S4 is a mixed atmosphere of hydrogen and argon, and the volume fraction of hydrogen in the mixed atmosphere accounts for 5 - 10%; the calcination temperature is 500 - 700 °C, and the calcination time is 1 - 2 hours.

[0016] A La / La2O2S@rGO Mott-Schottky heterojunction material, characterized in that it is prepared by the above preparation method.

[0017] The La / La2O2S@rGO heterojunction material prepared by the present invention is a Mott-Schottky heterojunction material, which uses the unique 4f orbitals of lanthanide metals to form multiple energy levels, promotes electron migration, and shows excellent performance in the field of electrocatalysis.

[0018] Application of a La / La2O2S@rGO Mott-Schottky heterojunction material, characterized in that the La / La2O2S@rGO Mott-Schottky heterojunction material prepared by the above preparation method is used to make an electrocatalytic material, and the electrocatalytic material is used for oxygen reduction reaction and oxygen evolution reaction, promoting its application in zinc-air batteries.

[0019] The La / La2O2S@rGO Mott-Schottky heterojunction material can be used as a bifunctional electrocatalyst for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), promoting its application in zinc-air batteries.

[0020] Furthermore, an application of a La / La2O2S@rGO Mott-Schottky heterojunction material: The preparation method of the electrocatalytic material includes the following steps:

[0021] (1) Mix Nafion resin, water, and isopropanol to obtain a mixed solution;

[0022] (2) Add the La / La2O2S@rGO Mott-Schottky heterojunction material to the mixed solution and ultrasonically disperse it evenly to obtain dispersion liquid B;

[0023] (3) Drop the dispersion liquid B onto a glassy carbon electrode and then dry it to obtain the electrocatalytic material, which can be used for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).

[0024] Furthermore, an application of a La / La2O2S@rGO Mott-Schottky heterojunction material: The preparation method of the electrocatalytic material includes the following specific steps:

[0025] (1) Mix Nafion resin, water, and isopropanol according to a volume ratio of 1:2:7 to obtain a mixed solution;

[0026] (2) Add the La / La2O2S@rGO Mott-Schottky heterojunction material to the mixed solution and ultrasonically disperse it evenly to obtain dispersion liquid B; wherein: the mass-volume ratio of the La / La2O2S@rGO Mott-Schottky heterojunction material to the mixed solution is 5 - 20 g / L; the ultrasonic temperature is 25 - 30 °C, the ultrasonic power is 800 - 1000 W, and the ultrasonic time is 15 - 30 minutes;

[0027] (3) Drop the dispersion liquid B onto a glassy carbon electrode and then dry it naturally to obtain the electrocatalytic material.

[0028] Advantages of the present invention:

[0029] (1) The present invention uses lanthanide metals as heterostructure builders. Their unique 4f orbitals form multiple energy levels, which is beneficial to the transition of electrons and improves the electrocatalytic performance of the material.

[0030] (2) The raw material metal lanthanum source used in the present invention has a wide source. It is cheaper and has a lower cost compared to commonly used noble metal compounds (RuO2 and Pt / C).

[0031] (3) The preparation method of the present invention has the advantages of simple operation, low cost, and easy regulation. When it is made into an electrocatalytic material and applied to the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), it can replace traditional expensive noble metal compound electrocatalysts. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 XRD pattern of the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in Example 1 of the present invention;

[0034] Figure 2 HRTEM image of the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in Example 4 of the present invention. Detailed Embodiments

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, of the embodiments of the present invention. The description of at least one exemplary embodiment is actually only illustrative and in no way restrictive of the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0036] Example 1

[0037] A preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material, comprising the following specific steps:

[0038] S1. Add lanthanum nitrate, L-cysteine, potassium citrate, and graphene oxide to deionized water at a molar ratio of 1:1:1.5:10, ultrasonicate, and stir at a rate of 1500 rpm for 30 minutes to fully dissolve them in water, obtaining dispersion A.

[0039] S2. Transfer dispersion A into a hydrothermal reaction kettle, then place the hydrothermal reaction kettle in an oven and react at 180 °C for 10 hours to obtain a precursor.

[0040] S3. Wash the precursor with water and ethanol respectively, and then dry it in an oven at 50 °C for 0.5 hours.

[0041] S4. Calcinate the precursor dried in step S3 at 600 °C for 1 hour in a tube furnace under a protective atmosphere (H2 / Ar = 5 / 95) to obtain the La / La2O2S@rGO Mott-Schottky heterojunction material.

[0042] Application: Fabricate an electrocatalytic material using the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in Example 1 above, and use the electrocatalytic material for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) to promote its application in zinc-air batteries; wherein: the preparation process of the electrocatalytic material includes the following specific steps:

[0043] (1) Mix Nafion resin, water, and isopropanol at a volume ratio of 1:2:7 to obtain a mixed solution.

[0044] (2) Take 1.0 mg of the prepared La / La2O2S@rGO Mott-Schottky heterojunction material and disperse it in 100 μL of the mixed solution, and ultrasonically disperse it evenly to obtain dispersion B; wherein: the ultrasonic temperature is 25 °C, the ultrasonic power is 800 W, and the ultrasonic time is 15 minutes.

[0045] (3) Take 10 μL of the above dispersion B and drop it onto a glassy carbon electrode, and then dry it naturally to obtain an electrocatalytic material, which can be used for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).

[0046] Test: Measure its ORR and OER catalytic performance using an electrochemical workstation. The onset potential and half-wave potential of ORR are as high as 0.94 V and 0.87 V, and the overpotential of OER at a current density of 10 mA / cm 2 is 310 mV.

[0047] The XRD of the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in Example 1 above is as Figure 1 shown, Figure 1 and characteristic peaks of metallic La and lanthanum oxysulfide La2O2S appear.

[0048] Example 2

[0049] A preparation method of La / La2O2S@rGO Mott-Schottky heterojunction material comprises the following specific steps:

[0050] S1. Add lanthanum nitrate, L-cysteine, potassium citrate and graphene oxide into deionized water according to a molar ratio of 1:2:1.5:10, ultrasonicate and stir at a rate of 1500 rpm for 40 minutes to fully dissolve them in water, obtaining dispersion A;

[0051] S2. Transfer the dispersion A into a hydrothermal reaction kettle, and then place the hydrothermal reaction kettle in an oven to react at 160 °C for 9 hours to obtain a precursor;

[0052] S3. Wash the precursor with water and ethanol respectively, and then dry it in an oven at 60 °C for 1 hour;

[0053] S4. Calcinate the precursor dried in step S3 at a high temperature of 550 °C in a tubular furnace under a protective atmosphere (H2 / Ar = 5 / 95) for 2 hours to obtain La / La2O2S@rGO Mott-Schottky heterojunction material.

[0054] Application: Fabricate the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in the above Example 2 into an electrocatalytic material, and use the electrocatalytic material for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) to promote its application in zinc-air batteries; wherein: the preparation process of the electrocatalytic material comprises the following specific steps:

[0055] (1) Mix Nafion resin, water and isopropanol according to a volume ratio of 1:2:7 to obtain a mixed solution;

[0056] (2) Take 1.0 mg of the prepared La / La2O2S@rGO Mott-Schottky heterojunction material and disperse it in 100 μL of the mixed solution, and ultrasonicate it evenly to obtain dispersion B; wherein: the ultrasonic temperature is 30 °C, the ultrasonic power is 800 W, and the ultrasonic time is 15 minutes;

[0057] (3) Take 10 μL of the above dispersion B and drop it on a glassy carbon electrode, and then dry it naturally to obtain an electrocatalytic material, which can be used for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).

[0058] Test: Measure its ORR and OER catalytic performance with an electrochemical workstation. The initial potential and half-wave potential of ORR are as high as 0.93 V and 0.85 V, and the overpotential of OER at a current density of 10 mA / cm 2 is 322 mV.

[0059] Example 3

[0060] A preparation method of La / La2O2S@rGO Mott-Schottky heterojunction material, comprising the following specific steps:

[0061] S1. Add lanthanum nitrate, L-cysteine, potassium citrate and graphene oxide to deionized water according to a molar ratio of 1:3:1.5:10, ultrasonicate and stir at a rate of 1800 rpm for 25 minutes to fully dissolve them in water to obtain dispersion A;

[0062] S2. Transfer the dispersion A into a hydrothermal reaction kettle, and then place the hydrothermal reaction kettle in an oven and react at 200 °C for 8 hours to obtain a precursor;

[0063] S3. Wash the precursor with water and ethanol respectively, and then dry it in an oven at 55 °C for 0.5 hour;

[0064] S4. Calcinate the precursor dried in step S3 at a high temperature of 650 °C in a tube furnace under a protective atmosphere (H2 / Ar = 5 / 95) for 1.5 hours to obtain La / La2O2S@rGO Mott-Schottky heterojunction material.

[0065] Application: Fabricate the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in Example 3 above into an electrocatalytic material, and use the electrocatalytic material for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) to promote its application in zinc-air batteries; wherein: the preparation process of the electrocatalytic material includes the following specific steps:

[0066] (1) Mix Nafion resin, water and isopropanol according to a volume ratio of 1:2:7 to obtain a mixed solution;

[0067] (2) Take 1.0 mg of the prepared La / La2O2S@rGO Mott-Schottky heterojunction material and disperse it in 100 μL of the mixed solution and ultrasonically disperse it evenly to obtain dispersion B; wherein: the ultrasonic temperature is 25 °C, the ultrasonic power is 900 W, and the ultrasonic time is 15 minutes;

[0068] (3) Take 10 μL of the above dispersion B and drop it on a glassy carbon electrode, and then dry it naturally to obtain an electrocatalytic material, which can be used for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).

[0069] Test: Measure its ORR and OER catalytic performance with an electrochemical workstation. The initial potential and half-wave potential of ORR are as high as 0.92 V and 0.84 V, and the overpotential of OER at a current density of 10 mA / cm 2 is 336 mV.

[0070] Example 4

[0071] A preparation method of La / La2O2S@rGO Mott-Schottky heterojunction material, comprising the following specific steps:

[0072] S1. Add lanthanum nitrate, L-cysteine, potassium citrate and graphene oxide into deionized water according to a molar ratio of 1:1:2:10, ultrasonically treat and stir at a rate of 2000 rpm for 35 minutes to fully dissolve them in water, obtaining dispersion A;

[0073] S2. Transfer the dispersion A into a hydrothermal reaction kettle, and then place the hydrothermal reaction kettle in an oven to react at 230 °C for 8 hours to obtain a precursor;

[0074] S3. Wash the precursor with water and ethanol respectively, and then dry it in an oven at 60 °C for 1 hour;

[0075] S4. Calcinate the precursor dried in step S3 at 500 °C for 2 hours in a tube furnace under a protective atmosphere (H2 / Ar = 5 / 95) to obtain La / La2O2S@rGO Mott-Schottky heterojunction material.

[0076] Application: Fabricate the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in Example 4 above into an electrocatalytic material, and use the electrocatalytic material for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) to promote its application in zinc-air batteries; wherein: the preparation process of the electrocatalytic material includes the following specific steps:

[0077] (1) Mix Nafion resin, water and isopropanol according to a volume ratio of 1:2:7 to obtain a mixed solution;

[0078] (2) Take 1.0 mg of the prepared La / La2O2S@rGO Mott-Schottky heterojunction material and disperse it in 100 μL of the mixed solution, and ultrasonically disperse it evenly to obtain dispersion B; wherein: the ultrasonic temperature is 28 °C, the ultrasonic power is 1000 W, and the ultrasonic time is 20 minutes;

[0079] (3) Take 10 μL of the above dispersion B and drop it on a glassy carbon electrode, and then dry it naturally to obtain an electrocatalytic material, which can be used for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).

[0080] Test: Use an electrochemical workstation to measure its ORR and OER catalytic performance. The initial potential and half-wave potential of ORR are as high as 0.94 V and 0.86 V respectively, and the overpotential of OER at a current density of 10 mA / cm 2 is 298 mV.

[0081] Figure 2High-resolution transmission electron microscopy (HRTEM) image of the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in Example 4 above. It can be clearly seen from Figure 2 the interface and lattice fringes of La and La2O2S.

[0082] Example 5

[0083] A preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material, comprising the following specific steps:

[0084] S1. Add lanthanum nitrate, L-cysteine, potassium citrate, and graphene oxide to deionized water according to a molar ratio of 1:3:1.5:10, ultrasonicate, and stir at a rate of 2000 rpm for 30 minutes to fully dissolve them in water to obtain dispersion A;

[0085] S2. Transfer dispersion A into a hydrothermal reaction kettle, then place the hydrothermal reaction kettle in an oven and react at 180 °C for 9 hours to obtain a precursor;

[0086] S3. Wash the precursor with water and ethanol respectively, and then dry it in an oven at 60 °C for 1 hour;

[0087] S4. Calcinate the precursor dried in step S3 at 600 °C in a tube furnace for 2 hours under a protective atmosphere (H2 / Ar = 5 / 95) to obtain a La / La2O2S@rGO Mott-Schottky heterojunction material.

[0088] Application: Use the La / La2O2S@rGO Mott-Schottky heterojunction material prepared in Example 5 above to make an electrocatalytic material, and use the electrocatalytic material for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) to promote its application in zinc-air batteries; wherein: the preparation process of the electrocatalytic material includes the following specific steps:

[0089] (1) Mix Nafion resin, water, and isopropanol according to a volume ratio of 1:2:7 to obtain a mixed solution;

[0090] (2) Take 1.0 mg of the prepared La / La2O2S@rGO Mott-Schottky heterojunction material and disperse it in 100 μL of the mixed solution, and ultrasonically disperse it evenly to obtain dispersion B; wherein: the ultrasonic temperature is 30 °C, the ultrasonic power is 1000 W, and the ultrasonic time is 30 minutes;

[0091] (3) Take 10 μL of the above dispersion B and drop it onto a glassy carbon electrode, and then dry it naturally to obtain an electrocatalytic material, which can be used for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).

[0092] Test: The ORR and OER catalytic performances were measured using an electrochemical workstation. The onset potential and half-wave potential of ORR were as high as 0.93 V and 0.86 V, respectively, and the overpotential of OER was 303 mV at a current density of 10 mA / cm 2 ².

[0093] The above are the preferred embodiments of the present invention, which are only used to explain the present invention and not to limit the present invention. Any obvious changes or variations derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A preparation method of La / La2O2S@rGO Mott-Schottky heterojunction material, characterized in that, The method includes the following steps: S1. Ultrasonically disperse a lanthanum source, a sulfur source, potassium citrate, and graphene oxide uniformly to obtain dispersion A; S2. Heat and react the dispersion A to obtain a precursor; S3. Wash and dry the precursor; S4. Calcinate the precursor dried in step S3 at a high temperature under a protective atmosphere to obtain a La / La2O2S@rGO Mott-Schottky heterojunction material; The prepared La / La2O2S@rGO Mott-Schottky heterojunction material is used to fabricate an electrocatalytic material, and the electrocatalytic material is used as a bifunctional electrocatalyst for the oxygen reduction reaction and the oxygen evolution reaction.

2. The preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material according to claim 1, characterized in that, Step S1. Add a lanthanum source, a sulfur source, potassium citrate, and graphene oxide to deionized water, ultrasonically stir uniformly, and obtain dispersion A; Among them, the molar ratio of the lanthanum source, the sulfur source, the potassium citrate, and the graphene oxide is 1:(1-3):(1-2):10; the stirring rate is 1500-2000 rpm, and the stirring time is 20-40 minutes.

3. The preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material according to claim 1 or 2, characterized in that, The lanthanum source in step S1 is lanthanum nitrate; the sulfur source is L-cysteine.

4. The preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material according to claim 1, characterized in that, Step S2. Transfer the dispersion A into a hydrothermal reaction kettle, and then place the hydrothermal reaction kettle in an oven at React at 150-230 °C for 8-10 hours to obtain a precursor.

5. The preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material according to claim 1, characterized in that Step S3. Wash the precursor with water and ethanol respectively, and then dry it in an oven at 50-60 °C for 0.5-1 hour.

6. The preparation method of a La / La2O2S@rGO Mott-Schottky heterojunction material according to claim 1, characterized in that, The protective atmosphere in step S4 is a mixed atmosphere of hydrogen and argon, and the volume fraction of hydrogen in the mixed atmosphere accounts for 5-10%; the calcination temperature is 500-700 °C, and the calcination time is 1-2 hours.

7. A La / La2O2S@rGO Mott-Schottky heterojunction material, characterized in that, Prepared by the preparation method according to any one of claims 1-6.

8. Use of a La / La2O2S@rGO Mott-Schottky heterojunction material according to claim 1, characterized in that, The preparation method of the electrocatalytic material includes the following steps: (1) Mix Nafion resin, water, and isopropanol to obtain a mixed solution; (2) Add the La / La2O2S@rGO Mott-Schottky heterojunction material to the mixed solution and ultrasonically disperse it uniformly to obtain dispersion B; (3) Drop the dispersion B onto a glassy carbon electrode, and then dry it to obtain the electrocatalytic material.

9. Use of a La / La2O2S@rGO Mott-Schottky heterojunction material according to claim 8, characterized in that, The preparation method of the electrocatalytic material includes the following specific steps: (1) Mix Nafion resin, water, and isopropanol according to a volume ratio of 1:2:7 to obtain a mixed solution; (2) Add the La / La2O2S@rGO Mott-Schottky heterojunction material to the mixed solution and ultrasonically disperse it uniformly to obtain dispersion B; Among them, the mass-volume ratio of the La / La2O2S@rGO Mott-Schottky heterojunction material to the mixed solution is 5-20 g / L; the ultrasonic temperature is 25-30 °C, the ultrasonic power is 800-1000 W, and the ultrasonic time is 15-30 minutes; (3) Drop the dispersion B onto a glassy carbon electrode, and then dry it naturally to obtain the electrocatalytic material.

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