A heteroatom-doped reduced graphene oxide material, a preparation method and applications thereof

Abstract

The application belongs to the technical field of carbon materials, and particularly relates to a kind of heteroatom doped reduced graphene oxide materials and its preparation method and application. The method adopts cyclic voltammetry, and the working electrode is pre-oxidized in a solution of sulfate salt; the working electrode after the pre-oxidation is subjected to redox reaction in a solution containing heteroatoms to obtain a heteroatom doped reduced graphene oxide material; the working electrode is a carbon material; the heteroatoms include one or more of nitrogen atoms, fluorine atoms, sulfur atoms and boron atoms. The method has mild reaction conditions, simple operation, strong controllability, and no side reactions occur. The heteroatom doped reduced graphene oxide material prepared has high electrochemical performance and catalytic activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon materials, and in particular relates to a heteroatom-doped reduced graphene oxide material and a preparation method and application thereof. Background Art

[0002] Carbon materials, due to their wide availability, safety, environmental friendliness, and structural tunability, have attracted widespread attention in energy and environmental fields, such as the development of efficient energy storage devices, water electrolysis, and electrochemical sensing. While traditional carbon materials possess excellent electrical conductivity and structural stability, they offer limited active sites during electrochemical reactions, limiting their storage capacity and catalytic performance.

[0003] Ion-doped carbon materials, especially heteroatom-doped carbon materials, have attracted widespread attention in fields such as electrochemical energy storage, electrochemical catalysis, and electrochemical sensing. By introducing foreign atoms into these materials to modify the electronic structure of carbon materials, they can effectively enhance their electrochemical properties, such as increasing conductivity, improving surface wettability, and providing more active sites, thereby exhibiting better performance in applications such as batteries, supercapacitors, and surface catalysis.

[0004] A variety of methods have been reported for preparing heteroatom-doped carbon materials, each with its own characteristics and scope of application. These methods include: pyrolysis, chemical vapor deposition (CVD), hydrothermal / solvothermal methods, template methods, direct mixing and calcination, electrochemical deposition, wet chemical methods, and laser-induced graphitization. Pyrolysis is the most commonly used method, but the pyrolysis process typically requires high temperatures, which can lead to side reactions that affect electrochemical performance and catalytic activity. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a heteroatom-doped reduced graphene oxide material and its preparation method and application. The method has mild reaction conditions, simple operation, strong controllability, and no side reactions. The prepared heteroatom-doped reduced graphene oxide material has high electrochemical performance and catalytic activity.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a heteroatom-doped reduced graphene oxide material, comprising the following steps:

[0008] Using cyclic voltammetry, the working electrode was pre-oxidized in a sulfate solution;

[0009] performing an oxidation-reduction reaction on the pre-oxidized working electrode in a solution containing heteroatoms to obtain a heteroatom-doped reduced graphene oxide material;

[0010] The working electrode is a carbon material;

[0011] The heteroatom includes one or more of a nitrogen atom, a fluorine atom, a sulfur atom and a boron atom.

[0012] Preferably, the carbon material is one or more of graphite paper, graphite rod, carbon paper and carbon brush.

[0013] Preferably, the heteroatom-containing solution is one or more of a nitrogen-containing solution, a fluorine-containing solution, a sulfur-containing solution and a boron-containing solution; the concentration of the solute in the nitrogen-containing solution is 1.5 to 2.5 mol / L; the concentration of the solute in the fluorine-containing solution is 1 to 2.5 mol / L; the concentration of the solute in the sulfur-containing solution is 1 to 2.5 mol / L; and the concentration of the solute in the boron-containing solution is 1 to 2.5 mol / L.

[0014] Preferably, the nitrogen-containing solution is one or more of ammonium nitrate solution, nitric acid solution, sodium nitrate solution, ammonium sulfate solution, ammonia solution and imidazolyl ionic liquid solution; the fluorine-containing solution is potassium fluoride solution and / or ammonium tetrafluoroborate solution; the sulfur-containing solution is thiosulfate solution and / or sulfite solution; the boron-containing solution is one or more of ammonium tetrafluoroborate solution, tetrafluoroborate ionic liquid solution, boric acid solution and sodium borohydride solution.

[0015] Preferably, the sulfate is one or more of sodium sulfate, potassium sulfate and magnesium sulfate; and the concentration of the sulfate in the sulfate solution is 0.5 to 1.5 mol / L.

[0016] Preferably, the parameters of the pre-oxidation treatment are: room temperature, initial voltage of 0-1V, maximum voltage of 1.5-2.5V, minimum voltage of 0-1V, scanning speed of 0.02-0.1V / s, number of scanning circles of 10-100 circles, current density of 5-200mA / cm 2 .

[0017] Preferably, the parameters of the redox reaction are: room temperature, initial voltage of 0-1V, maximum voltage of 1.5-3V, minimum voltage of -1.2-0.8V, scanning speed of 0.02-0.05V / s, number of scanning circles of 50-300 circles, and current density of 5-200mA / cm 2 .

[0018] Preferably, the cyclic voltammetry is performed using a three-electrode system; in the three-electrode system, the counter electrode is a platinum wire or a platinum sheet, and the reference electrode is an Ag / AgCl electrode or a calomel electrode.

[0019] The present invention also provides a heteroatom-doped reduced graphene oxide material prepared by the preparation method described in the above technical solution, comprising reduced graphene oxide and heteroatoms doped on the surface and between layers of the reduced graphene oxide;

[0020] The heteroatom includes one or more of nitrogen, fluorine, sulfur and boron atoms;

[0021] The nitrogen atoms are doped in the form of pyridinic nitrogen, pyrrolic nitrogen or graphitic nitrogen, wherein the pyridinic nitrogen or pyrrolic nitrogen is formed by nitrogen atoms and carbon atoms in the reduced graphene oxide, the boron atoms are doped in the form of replacing carbon atoms, the sulfur atoms are doped in a manner of forming SC covalent bonds, and the fluorine atoms are doped in a manner of forming CF covalent bonds.

[0022] The present invention also provides the use of the heteroatom-doped reduced graphene oxide material described in the above technical solution in an electrode, wherein the electrode includes one or more of an electrochemical sensing electrode, an energy storage electrode and an electrolysis electrode.

[0023] The present invention provides a preparation method of a heteroatom-doped reduced graphene oxide material. The method comprises the following steps: pre-oxidizing a working electrode in a sulfate solution by using cyclic voltammetry; performing an oxidation-reduction reaction on the pre-oxidized working electrode in a solution containing heteroatoms to obtain the heteroatom-doped reduced graphene oxide material; the working electrode is a carbon material; and the heteroatoms include one or more of nitrogen atoms, fluorine atoms, sulfur atoms and boron atoms.

[0024] The present invention adopts cyclic voltammetry, and the carbon material is converted into a heteroatom-doped reduced graphene oxide material through ion intercalation, oxidation, and reduction. In this process, as the positive overpotential increases, the carbon material is oxidized to form oxygen-containing functional groups such as hydroxyl, epoxy, and carboxyl groups at the edge. At the same time, the interlayer spacing gradually opens under the action of hydrolysis bubbles, and then the heteroatoms are inserted into the interlayer and adsorbed on the oxygen-containing functional groups or planes through electrostatic attraction, cation-π, hydrogen bonds, etc., and oxidative dehydrogenation is simultaneously performed. When the scanning potential is reversed, as the negative overpotential increases, the oxygen-containing functional groups adsorbed heteroatoms are reduced and hydrogenated, and the heteroatoms are embedded in the lattice of the carbon material, thereby giving the material high electrochemical performance and catalytic activity. The method has mild reaction conditions, simple operation, environmental friendliness, strong controllability, low cost, no side reactions, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 CV curve of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1;

[0026] Figure 2 This is the XPS graph of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1;

[0027] Figure 3 CV curve of the fluorine atom-doped reduced graphene oxide material prepared in Example 2;

[0028] Figure 4 This is the XPS graph of the fluorine atom-doped reduced graphene oxide material prepared in Example 2;

[0029] Figure 5 CV curve of the boron atom-doped reduced graphene oxide material prepared in Example 3;

[0030] Figure 6 This is the XPS graph of the boron atom-doped reduced graphene oxide material prepared in Example 3;

[0031] Figure 7 CV curve of the sulfur atom-doped reduced graphene oxide material prepared in Example 4;

[0032] Figure 8 This is the XPS graph of the sulfur atom-doped reduced graphene oxide material prepared in Example 4;

[0033] Figure 9 The Raman, XRD, and XPS test results of the nitrogen-doped graphene oxide prepared in Comparative Example 1 are shown;

[0034] Figure 10 This is an XPS test result diagram of the sulfur-doped graphene oxide prepared in Comparative Example 2;

[0035] Figure 11 This is a Mott-Schottky curve of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1;

[0036] Figure 12 This is a Mott-Schottky curve diagram of the boron atom-doped reduced graphene oxide material prepared in Example 3;

[0037] Figure 13 This is a Mott-Schottky curve diagram of the sulfur atom-doped reduced graphene oxide material prepared in Example 4;

[0038] Figure 14 This is the original data graph of the Tafel curve test of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1;

[0039] Figure 15 This is a fitting diagram of the Tafel curve test of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1;

[0040] Figure 16 This is an electrochemical impedance spectroscopy (EIS) test graph of the fluorine atom-doped reduced graphene oxide material prepared in Example 2;

[0041] Figure 17 CV test graph of nitrogen-doped graphene oxide prepared in Comparative Example 1;

[0042] Figure 18 This is the CV test graph of sulfur-doped graphene oxide prepared in Comparative Example 2. DETAILED DESCRIPTION

[0043] The present invention provides a method for preparing a heteroatom-doped reduced graphene oxide material, which is characterized by comprising the following steps:

[0044] Using cyclic voltammetry, the working electrode was pre-oxidized in a sulfate solution;

[0045] performing an oxidation-reduction reaction on the pre-oxidized working electrode in a solution containing heteroatoms to obtain a heteroatom-doped reduced graphene oxide material;

[0046] The working electrode is a carbon material;

[0047] The heteroatom includes one or more of a nitrogen atom, a fluorine atom, a sulfur atom and a boron atom.

[0048] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used, and commercially available products known to those skilled in the art can be used.

[0049] In one embodiment, the carbon material is a block carbon material; the carbon material is one or more of graphite paper, graphite rod, carbon paper, and carbon brush, and in a specific embodiment, graphite paper is used. Graphite paper is widely available, inexpensive, and easily available.

[0050] In one embodiment, the cyclic voltammetry is performed using a three-electrode system; the counter electrode in this three-electrode system is a platinum wire or platinum sheet, specifically a platinum wire, and the reference electrode is an Ag / AgCl electrode or a calomel electrode, specifically an Ag / AgCl electrode. Platinum is highly inert and is a common counter electrode material. Platinum wire has a small surface area and is more suitable for low current densities. The Ag / AgCl electrode offers stable potential and a wide pH range of application.

[0051] In one embodiment, the sulfate is one or more of sodium sulfate, potassium sulfate, and magnesium sulfate, with sodium sulfate being a specific example. The concentration of the sulfate in the sulfate solution is 0.5 to 1.5 mol / L, with a specific example of 1 to 2 mol / L. Sulfate does not introduce other foreign atoms but can intercalate between graphite layers and promote hydrolysis and oxidation.

[0052] As an embodiment, the parameters of the pre-oxidation treatment are: the temperature is room temperature, 15 to 25 ° C in the specific embodiment, the initial voltage is set to 0 to 1 V, 0 V in the specific embodiment, the maximum voltage is set to 1.5 to 2.5 V, 1.8 to 2.1 V in the specific embodiment, the minimum voltage is set to 0 to 1 V, 0 V in the specific embodiment, the scanning speed is 0.02 to 0.1 V / s, 0.03 to 0.05 V / s in the specific embodiment, the number of scanning circles is 10 to 100 circles, 10 to 75 circles in the specific embodiment, and the current density is 5 to 200 mA / cm 2 , in the specific embodiment, 10 to 100 mA / cm 2 .

[0053] The present invention uses a pre-oxidation treatment to open up the interlayer spacing of the carbon material, laying the foundation for the subsequent heteroatom doping. The pre-oxidation treatment in the present invention can open up the interlayer spacing, facilitating the subsequent insertion of heteroatom-containing ions into the graphite interlayers. The pre-oxidation conditions precisely open up the graphite interlayer spacing without destroying the apparent structure of the carbon material.

[0054] As an embodiment, the heteroatom-containing solution is one or more of a nitrogen-containing solution, a fluorine-containing solution, a sulfur-containing solution and a boron-containing solution, and in a specific embodiment, it is a nitrogen-containing solution, a fluorine-containing solution, a sulfur-containing solution or a boron-containing solution; the nitrogen-containing solution is one or more of an ammonium nitrate solution, a nitric acid solution, a sodium nitrate solution, an ammonium sulfate solution, an ammonia solution and an imidazolyl ionic liquid solution, and in a specific embodiment, it is an ammonium nitrate solution; the concentration of the solute in the nitrogen-containing solution is 1.5 to 2.5 mol / L, and in a specific embodiment, it is 1.5 to 2 mol / L; the fluorine-containing solution is a potassium fluoride solution and / or an ammonium tetrafluoroborate solution, and in a specific embodiment, it is a potassium fluoride solution; the solute in the fluorine-containing solution is The concentration is 1 to 2.5 mol / L, and in a specific embodiment, it is 1 to 2 mol / L; the sulfur-containing solution is a thiosulfate solution and / or a sulfite solution, and in a specific embodiment, it is a thiosulfate solution; the thiosulfate is sodium thiosulfate; the concentration of the solute in the sulfur-containing solution is 1 to 2.5 mol / L, and in a specific embodiment, it is 1.25 to 2 mol / L; the boron-containing solution is one or more of an ammonium tetrafluoroborate solution, a tetrafluoroborate ionic liquid solution, a boric acid solution, and a sodium borohydride solution, and in a specific embodiment, it is an ammonium tetrafluoroborate solution; the concentration of the solute in the boron-containing solution is 1 to 2.5 mol / L, and in a specific embodiment, it is 1.5 to 2 mol / L.

[0055] In the present invention, the use of ammonium nitrate solution can simultaneously provide two nitrogen sources, anion and cation, to obtain a high-concentration nitrogen-doped material; the use of potassium fluoride solution can obtain a higher fluorine doping amount without introducing other foreign atoms; the use of ammonium tetrafluoroborate solution can obtain a high B doping amount and form multiple doping types; thiosulfate and sulfite can form SC bonds instead of C-SOx.

[0056] As an embodiment, the parameters of the redox reaction are: the temperature is room temperature, 15 to 25 ° C in a specific embodiment, the initial voltage is set to 0 to 1 V, 0 V in a specific embodiment, the maximum voltage is set to 1.5 to 3 V, 1.7 to 2.5 V in a specific embodiment, the minimum voltage is set to -1.2 to -0.8 V, -1.2 to -1.0 V in a specific embodiment, the scanning speed is 0.02 to 0.05 V / s, 0.03 to 0.04 V / s in a specific embodiment, the number of scanning circles is 50 to 300 circles, 100 to 200 circles in a specific embodiment, and the current density is 5 to 200 mA / cm 2 , in the specific embodiment, 10 to 100 mA / cm 2 .

[0057] The carbon material is converted into heteroatom-doped reduced graphene oxide through ion intercalation, oxidation, and reduction. During this process, as the positive overpotential increases, the carbon material is first oxidized, forming oxygen-containing functional groups such as hydroxyl, epoxy, and carboxyl groups at the edges. Simultaneously, the interlayer spacing gradually widens under the action of hydrolysis bubbles. Heteroatoms then insert into the interlayers, adsorbing onto oxygen-containing functional groups or planes through electrostatic attraction, cation-π interactions, and hydrogen bonding, while undergoing simultaneous oxidative dehydrogenation. When the scanning potential is reversed, as the negative overpotential increases, the oxygen-containing functional groups adsorbed with heteroatoms undergo reduction and hydrogenation, embedding the heteroatoms into the carbon material's lattice, resulting in the material's high electrochemical performance and catalytic activity.

[0058] The parameters of the redox reaction mainly affect the degree of oxidation and reduction of carbon materials, the degree of embedding and hydrolysis of ions containing heteroatoms, and the type of doping. Generally, the wider the voltage range and the slower the scanning speed, the more conducive it is to generate more defect sites and improve the electrochemical activity of carbon materials.

[0059] Within a certain range, lower current density and higher forward overpotential facilitate the slow embedding of heteroatom-containing ions into the graphite interlayers, generating more oxygen-containing functional groups and, during reduction and deoxygenation, more defects for heteroatom doping. The presence of heteroatoms of varying ion types in the heteroatom-containing solution is beneficial for increasing the heteroatom doping concentration. Controlling these conditions can alter the electronic structure of graphene, adjust the band gap, create more electron donor and electron acceptor sites, and enhance the electrochemical activity and conductivity of heteroatom-doped reduced graphene oxide, thereby improving the efficiency of its catalytic reaction.

[0060] Compared to constant-voltage electrochemical stripping techniques, the cyclic voltammetry method employed in this study allows for precise control of heteroatom doping by flexibly controlling the redox environment. This method allows for the preparation of thin-film graphene-like materials in a single step, making them more suitable for use as electrode materials for electrochemical sensing, without the need for secondary processing.

[0061] In terms of preparation methods, the present invention is low-cost, has mild reaction conditions, high sensitivity, is convenient and fast, is simple to operate, is environmentally friendly, has strong controllability, does not produce side reactions, and is suitable for large-scale production. In terms of application prospects, the present invention is expected to be able to accurately monitor new pollutants by sensing and monitoring on an electrochemical workstation through the combination of electron transfer and active sites occurring on the surface of pollutants. At the same time, by adjusting parameters such as current density, voltage, doping solution (solution containing heteroatoms) composition, and temperature, the interlayer spacing, heteroatom doping amount, functional group structure, defects and other microstructures of the carbon material can be precisely controlled.

[0062] The present invention also provides a heteroatom-doped reduced graphene oxide material prepared by the preparation method described in the above technical solution, comprising reduced graphene oxide and heteroatoms doped on the surface and between layers of the reduced graphene oxide;

[0063] The heteroatom includes one or more of nitrogen, fluorine, sulfur and boron atoms;

[0064] The nitrogen atoms are doped in the form of pyridinic nitrogen, pyrrolic nitrogen or graphitic nitrogen, wherein the pyridinic nitrogen or pyrrolic nitrogen is formed by nitrogen atoms and carbon atoms in the reduced graphene oxide, the boron atoms are doped in the form of replacing carbon atoms, the sulfur atoms are doped in a manner of forming SC covalent bonds, and the fluorine atoms are doped in a manner of forming CF covalent bonds.

[0065] As an embodiment, the heteroatom is a nitrogen atom, a fluorine atom, a sulfur atom or a boron atom; and the CF covalent bond includes an ionic CF bond and a semi-ionic CF bond.

[0066] As an embodiment, the mass percentage of heteroatoms in the heteroatom-doped reduced graphene oxide material is 1 to 5%, specifically 2.39%, 1.17% or 1% in specific embodiments, and the mass percentage of reduced graphene oxide is 95 to 99%, specifically 97.61%, 98.83% or 99% in specific embodiments.

[0067] Heteroatom doping changes the electronic structure of carbon materials, effectively improving their electrochemical properties, enhancing conductivity, improving surface wettability, and providing more active sites to enhance their catalytic activity. Among them, nitrogen atom doping can increase the free electron density in reduced graphene oxide materials, which can improve their electrocatalytic activity, conductivity and surface wettability. Nitrogen usually exists in the form of pyridinic nitrogen, pyrrolic nitrogen and graphitic nitrogen. Boron doping causes holes to appear in the carbon lattice, enhancing the p-type semiconductor properties of carbon materials and improving their mechanical strength and thermal stability. Boron mainly exists in carbon materials in the form of substituted carbon atoms. Sulfur doping helps to improve the lithium storage capacity, capacitance performance and redox activity of carbon materials, making them suitable for supercapacitors and battery electrode materials. Sulfur is doped by forming covalent bonds with carbon materials. Fluorine doping can change the surface chemical properties of carbon materials, making them more hydrophobic and potentially improving the material's oxidation resistance and corrosion resistance. Fluorine is also doped by forming covalent bonds with carbon materials.

[0068] The present invention also provides the use of the heteroatom-doped reduced graphene oxide material described in the above technical solution in an electrode.

[0069] As an embodiment, the electrode includes one or more of an electrochemical sensing electrode, an energy storage electrode and an electrolysis electrode, and in a specific embodiment, the electrode is an electrochemical sensing electrode.

[0070] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention, but they should not be understood as limiting the scope of protection of the present invention.

[0071] Example 1

[0072] An electrochemical reaction device was constructed using graphite paper as the working electrode, platinum wire as the counter electrode, and Ag / AgCl as the reference electrode. Cyclic voltammetry was first performed using a 1 mol / L sodium sulfate solution for pre-oxidation: the temperature was 25 °C, the initial voltage was set to 0 V, the maximum voltage was set to 2 V, the minimum voltage was set to 0 V, the scan rate was 0.05 V / s, and the current density was 10 mA / cm 2 After 10 cycles of pre-oxidation treatment, cyclic voltammetry was used to carry out the redox reaction. 2.5 mol / L ammonium nitrate solution was selected as the doping solution for doping N atoms. The temperature was 25 °C, the initial voltage was set to 0 V, the maximum voltage was set to 2.1 V, the minimum voltage was set to -1.2 V, the scan rate was 0.05 V / s, and the current density was 5 mA / cm 2 After 100 cycles of scanning, nitrogen atom-doped reduced graphene oxide material was obtained.

[0073] Example 2

[0074] The difference from Example 1 is that 1 mol / L potassium fluoride solution is selected as the doping liquid to dope F atoms, the maximum voltage in the pre-oxidation treatment is set to 2.5 V, the scanning speed is 0.1 V / s, the number of scanning circles is 75 circles, and during the redox reaction, the maximum voltage is set to 1.9 V and the minimum voltage is set to -1.2 V. The remaining assembly steps are the same as in Example 1 to obtain fluorine atom-doped reduced graphene oxide material.

[0075] Example 3

[0076] The difference from Example 1 is that 1.5 mol / L ammonium tetrafluoroborate solution is selected as the doping liquid to dope B atoms, the maximum voltage is set to 2 V in the pre-oxidation treatment, the maximum voltage is set to 1.7 V during the redox reaction, and the minimum voltage is set to -1.2 V. The remaining assembly steps are the same as in Example 1 to obtain a boron atom-doped reduced graphene oxide material.

[0077] Example 4

[0078] The difference from Example 1 is that a 1.25 mol / L sodium thiosulfate solution is selected as the doping liquid to dope S atoms, the maximum voltage in the pre-oxidation treatment is set to 2 V, and during the redox reaction, the maximum voltage is set to 1.7 V and the minimum voltage is set to -1.2 V. The remaining assembly steps are the same as in Example 1 to obtain a sulfur atom-doped reduced graphene oxide material.

[0079] Comparative Example 1

[0080] An electrochemical reaction device was constructed using a graphite rod as a working electrode, a platinum wire as a counter electrode, and Ag / AgCl as a reference electrode. Ethylammonium nitrate containing 10% (v / v) water was selected as the electrolyte. The constant voltage method was adopted, and electrolysis was carried out at 25°C and 2.2V for 20 minutes until complete exfoliation, finally obtaining nitrogen-doped graphene oxide.

[0081] Comparative Example 2

[0082] An electrochemical reaction device was constructed using a graphite rod as the working electrode, a platinum wire as the counter electrode, and Ag / AgCl as the reference electrode. An ammonium sulfate solution containing 1.5 mol / L was selected as the electrolyte. The constant current method was adopted. Electrolysis was carried out at 25°C and a static current of 1.0 A for 2 h until complete exfoliation, and sulfur-doped graphene oxide was finally obtained.

[0083] Comparative Example 3

[0084] The electrochemical deposition method uses a conductive material as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl reference electrode to construct an electrochemical reaction device. A deoxygenated acidic ionic liquid solution is used as the electrolyte, and the graphene oxide to be doped exists in a colloidal state within the electrolyte. Electrolytic reduction is carried out at a constant potential of -1.0V, ultimately yielding nitrogen-doped reduced graphene oxide in situ supported on the conductive material. Compared to this method, the present invention offers two advantages: first, the doping target is a solid carbon material, eliminating the need for a conductive material. This allows for direct structural control of the solid electrode material, eliminating the need for subsequent processing and resulting in improved stability. Second, defect control is more precise, with the desired doping type controlled through cyclic oxidation and reduction.

[0085] Performance Testing

[0086] (1) Figure 1 This is a CV curve diagram of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1.

[0087] from Figure 1 It can be seen that in the cyclic voltammetry, when the current is positive, the curve rises, indicating that an oxidation reaction occurs at the electrode and nitrate ions are embedded in the interlayer. When the current is negative, a reduction reaction and the embedding of ammonium ions occur. Two reduction peaks appear, representing the reduction of nitrate and graphene oxide respectively. After 100 cycles, nitrogen atom-doped reduced graphene oxide material is formed.

[0088] (2) Figure 2 This is the XPS graph of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1.

[0089] from Figure 2 It can be seen that the XPS test can illustrate the type of N element doping. Nitrogen atoms doped into reduced graphene oxide material form two types of N doping, of which graphitic nitrogen contains 45.88% and pyrrolic nitrogen contains 54.12%, indicating that this method successfully doped N atoms into carbon materials.

[0090] (3) Figure 3 This is a CV curve diagram of the fluorine atom-doped reduced graphene oxide material prepared in Example 2.

[0091] from Figure 3 It can be seen that in the cyclic voltammetry, when the current is positive, the curve rises, indicating that an oxidation reaction occurs at the electrode and fluoride ions are embedded in the interlayer. When the current is negative, a reduction reaction occurs, and two reduction peaks appear, representing fluoride ion doping and the reduction of graphene oxide. After 100 cycles, fluorine atom-doped reduced graphene oxide material is formed.

[0092] (4) Figure 4 This is the XPS graph of the fluorine atom-doped reduced graphene oxide material prepared in Example 2.

[0093] from Figure 4 As can be seen from the XPS image, two peaks related to CF are observed, which is consistent with the conclusion of F doping obtained from the literature: ionic CF bonds account for 60.29% and semi-ionic CF bonds account for 39.71%. In summary, this method successfully incorporates F atoms into carbon materials.

[0094] (5) Figure 5 This is a CV curve diagram of the boron atom-doped reduced graphene oxide material prepared in Example 3.

[0095] from Figure 5 It can be seen that in the cyclic voltammetry, when the current is positive, the curve rises, indicating that an oxidation reaction occurs at the electrode and tetrafluoroborate ions are embedded in the interlayer. When the current is negative, the curve drops, indicating that a reduction reaction occurs in the material. After 100 cycles, boron atom-doped reduced graphene oxide material is formed.

[0096] (6) Figure 6 This is the XPS graph of the boron atom-doped reduced graphene oxide material prepared in Example 3.

[0097] from Figure 6 It can be seen that the XPS test can illustrate the type of B element doping. Boron atoms doped into reduced graphene oxide materials form two types of B doping, of which BCO2 contains 82.06% and BC2O contains 17.94%, indicating that this method successfully doped B atoms into carbon materials.

[0098] (7) Figure 7 This is a CV curve diagram of the sulfur atom-doped reduced graphene oxide material prepared in Example 4.

[0099] from Figure 7 It can be seen that in the cyclic voltammetry, when the current is positive, the curve rises, indicating that an oxidation reaction occurs at the electrode and thiosulfate ions are embedded in the interlayer. When the current is negative, the curve drops, indicating that a reduction reaction occurs between the material and the thiosulfate. After 100 cycles, S-doped graphene material is formed.

[0100] (8) Figure 8 This is the XPS graph of the sulfur atom-doped reduced graphene oxide material prepared in Example 4.

[0101] from Figure 8 It can be seen that the XPS test can illustrate the type of S element doping. Sulfur atoms doped into reduced graphene oxide materials form two types of S doping, of which CSC accounts for 43.65% and C-SOx accounts for 56.35%, indicating that this method successfully doped S atoms into carbon materials.

[0102] (9) The nitrogen-doped graphene oxide prepared in Example 1 was subjected to Raman, XRD, and XPS tests. The results are as follows: Figure 9As shown, (a) is the Raman test pattern, (b) is the XRD test pattern, (c) is the XPS total spectrum, and (d) is the N-doping spectrum of XPS.

[0103] Depend on Figure 9 As can be seen from (a), (b), (c) and (d), nitrogen-doped graphene oxide is formed in Comparative Example 1. The main difference is that the material prepared in Example 1 is in thin film form, which is more conducive to being used as an electrode material and does not require secondary treatment, while the material prepared in Comparative Example 1 is in powder form. In addition, Comparative Example 1 uses a constant voltage method to continuously oxidize to obtain exfoliated graphene oxide powder, and the degree of doping and oxidation is uncontrollable, while Example 1 is to apply cyclic forward and reverse voltages, and graphite is repeatedly oxidized and reduced to form a thin film-like graphene. This process can accurately control the doping type, while maintaining good conductivity, it can also utilize the abundant defect sites on the surface to promote electron transfer and quickly identify pollutants.

[0104] (10) The sulfur-doped graphene oxide prepared in Comparative Example 2 was subjected to XPS testing, and the results were as follows: Figure 10 As shown, a is the S-doped spectrum of XPS, and b is the N-doped spectrum of XPS.

[0105] Depend on Figure 10 As shown in a and b, comparative example 2 forms S / N co-doped graphene oxide. Example 4 can form CSC type doping, which can better change the electronic structure of carbon nanomaterials, adjust the band gap structure, form electron donor and electron acceptor sites, and improve the catalytic ability of the material.

[0106] (11) Figures 11-13 These are Mott-Schottky curves of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1, the boron atom-doped reduced graphene oxide material prepared in Example 3, and the sulfur atom-doped reduced graphene oxide material prepared in Example 4.

[0107] from Figures 11-13 It can be seen that this testing technology can show that the semiconductor types of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1, the boron atom-doped reduced graphene oxide material prepared in Example 3, and the sulfur atom-doped reduced graphene oxide material prepared in Example 4 are n-type, p-type, and p-type, respectively, and the flat band potentials are -0.287 eV, 0.792 eV, and 0.796 eV, respectively: this parameter is closely related to the Fermi level position of the material and is a key indicator for evaluating the band structure of semiconductors in electrolytes.

[0108] (12) Figure 14 This is the original data graph of the Tafel curve test of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1. Figure 15It is a fitting graph of the Tafel curve test of the nitrogen atom-doped reduced graphene oxide material prepared in Example 1. The test uses a three-electrode system with a scanning voltage range of 0 to 100 mV, pure water or tetracycline as the electrolyte, and a scanning speed of 1 mV / s. DL+NGO refers to the nitrogen atom-doped reduced graphene oxide material prepared in Example 1 as the working electrode and pure water as the electrolyte for Tafel test; TC+NGO refers to the nitrogen atom-doped reduced graphene oxide material prepared in Example 1 as the working electrode and tetracycline as the electrolyte for Tafel test; TC+NGO (adsorption saturated PMS) refers to the nitrogen atom-doped reduced graphene oxide material prepared in Example 1 that is fully adsorbed with PMS as the working electrode and tetracycline as the electrolyte for Tafel test, and then the straight line portion (60 mV to 80 mV) on the Tafel curve is fitted to obtain Figure 15 .

[0109] Depend on Figure 14 and Figure 15 It can be seen that this test verifies the ability of the prepared material to activate electron transfer between persulfate and new pollutant antibiotics. From the fitted quadratic function, it can be seen that the slope of the blue curve is the largest, indicating that the material has strong electron transfer ability and good catalytic activity.

[0110] (13) Figure 16 This is the electrochemical impedance spectroscopy (EIS) test diagram of the fluorine atom-doped reduced graphene oxide material prepared in Example 2. The diameter of the semicircle in the mid-frequency region corresponds to the charge transfer resistance Rct. Figure 16 It can be seen that the measured diameter is small, which means that the material has low resistance and good conductivity.

[0111] (14) Figure 17 This is the CV test graph of nitrogen-doped graphene oxide prepared in Comparative Example 1. Figure 18 This is the CV test graph of sulfur-doped graphene oxide prepared in Comparative Example 2.

[0112] Depend on Figure 17 、 Figure 18 It can be seen that the CV test graphs of the nitrogen-doped graphene oxide prepared in Comparative Example 1 and the nitrogen-doped reduced graphene oxide material prepared in Example 1 ( Figure 1 ) are compared, and the CV test graph of the sulfur-doped graphene oxide prepared in Comparative Example 2 is compared with the CV curve graph of the sulfur-doped reduced graphene oxide material prepared in Example 4 ( Figure 7 ), the heteroatom-doped reduced graphene oxide material prepared by the present invention can withstand a wider scanning voltage range and more scanning cycles, indicating that the heteroatom-doped reduced graphene oxide material prepared by the present invention has better stability.

[0113] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing heteroatom-doped reduced graphene oxide material, characterized in that: The following steps are involved: Using cyclic voltammetry, the working electrode was pre-oxidized in a sulfate solution; performing an oxidation-reduction reaction on the pre-oxidized working electrode in a solution containing heteroatoms to obtain a heteroatom-doped reduced graphene oxide material; The working electrode is a carbon material; The heteroatoms include nitrogen atoms and / or boron atoms; The carbon material is one or more of graphite paper, graphite rod, carbon paper and carbon brush; The heteroatom-containing solution is a nitrogen-containing solution and / or a boron-containing solution; the concentration of the solute in the nitrogen-containing solution is 1.5 to 2.5 mol / L; the concentration of the solute in the boron-containing solution is 1 to 2.5 mol / L; The nitrogen-containing solution is one or more of ammonium nitrate solution, sodium nitrate solution, ammonium sulfate solution and ammonia solution; the boron-containing solution is ammonium tetrafluoroborate solution and / or boric acid solution; The sulfate is one or more of sodium sulfate, potassium sulfate and magnesium sulfate; the concentration of the sulfate in the sulfate solution is 0.5-1.5 mol / L; The parameters of the pre-oxidation treatment are: room temperature, initial voltage of 0-1V, maximum voltage of 1.5-2.5V, minimum voltage of 0-1V, scanning speed of 0.02-0.1V / s, number of scanning circles of 10-100 circles, and current density of 5-200mA / cm 2 ; The parameters of the redox reaction are: room temperature, initial voltage 0-1 V, maximum voltage 1.5-3 V, minimum voltage -1.2-0.8 V, scan speed 0.02-0.05 V / s, scan number 50-300, current density 5-200 mA / cm 2 .

2. The preparation method according to claim 1, characterized in that The cyclic voltammetry is performed using a three-electrode system; in the three-electrode system, the counter electrode is a platinum wire or a platinum sheet, and the reference electrode is an Ag / AgCl electrode or a calomel electrode.

3. The heteroatom-doped reduced graphene oxide material prepared by the preparation method according to any one of claims 1 to 2, characterized in that: comprising reduced graphene oxide and heteroatoms doped on the surface of the reduced graphene oxide; The heteroatoms include nitrogen atoms and / or boron atoms; The nitrogen atoms are doped in the form of pyridinic nitrogen, pyrrolic nitrogen or graphitic nitrogen, which are formed by nitrogen atoms and carbon atoms in the reduced graphene oxide. The boron atoms are doped in the form of replacing carbon atoms.

4. The use of the heteroatom-doped reduced graphene oxide material according to claim 3 in an electrode, characterized in that: The electrodes include electrochemical sensing electrodes and / or electrolysis electrodes.

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