Carbon-based catalysts with two tellurium coordination structures, and preparation method and application thereof

Abstract

The application discloses a carbon-based catalyst with two tellurium coordination structures and a preparation method and application thereof, and belongs to the technical field of electrochemical catalysis. The method disclosed by the application uses two tellurium precursors with different structures, namely metalloid Te powder and oxide TeO2, which are combined with graphene oxide (GO) under severe alcohol thermal reaction conditions; then, the introduced precursor coordination structure is destroyed and re-modified in a further high-temperature environment through a chemical vapor deposition method, thereby forming a single-atom catalyst (Te / TeO2-NC) with two tellurium coordination structures, and the activity of the catalyst in generating hydrogen peroxide is greatly improved. The hydrogen peroxide electrocatalyst with high performance is synthesized through alcohol thermal reaction and the chemical vapor deposition method, and the method is simple, and raw materials are cheap and easy to obtain; in addition, the carbon-based catalyst has high electrocatalytic activity, hydrogen peroxide selectivity and stability in the performance test of 0.1M KOH, and is a non-noble metal catalyst with good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysis technology, specifically relating to a carbon-based catalyst with two tellurium coordination structures, its preparation method, and its application. Background Technology

[0002] Hydrogen peroxide (H2O2) is an important and fundamental chemical widely used in various industries, including papermaking, disinfection, wastewater treatment, and chemical synthesis. Currently, the industrial method for large-scale H2O2 production is the anthraquinone cycle process. This traditional method not only consumes large amounts of H2 and other energy sources, generating significant amounts of organic waste, but also requires complex separation processes to obtain high-purity H2O2 for use. There is an urgent need for alternative strategies for H2O2 synthesis to reduce energy consumption, pollution, and production costs. Currently, the electrochemical synthesis of H2O2 via the two-electron transfer process in the oxygen reduction reaction (ORR) has attracted widespread attention. The 2e-ORR process can achieve green, energy-saving, simple, and safe H2O2 synthesis, making it a promising alternative to the traditional anthraquinone method. Developing high-performance catalysts for the 2e-ORR is key to achieving large-scale electrosynthesis of H2O2. Although some noble metal-based electrocatalysts (e.g., palladium, platinum-mercury, palladium-mercury) are highly efficient in this process, the high cost and scarcity of noble metals hinder their widespread application. Therefore, it is imperative to develop cost-effective alternatives with high activity and selectivity to catalyze 2e-ORR.

[0003] Non-metallic carbon nanomaterials (graphene, carbon black, carbon nanotubes, etc.) have attracted widespread attention in the field of 2e-ORR electrocatalysis due to their high chemical stability and low cost. Graphene, with its large specific surface area, is an excellent catalyst support, but its intrinsic activity as a direct catalyst is poor and its kinetics are slow. Currently, introducing active sites by doping graphene is a feasible method for fabricating good 2e-ORR catalysts. However, catalysts synthesized by graphene doping suffer from kinetic and thermodynamic instability, preventing them from stably and efficiently producing hydrogen peroxide in electrocatalysis, thus greatly limiting the practical application of graphene-based catalysts. Therefore, selectively controlling the introduction of elements and the resulting coordination structures in graphene doping presents a promising challenge for obtaining highly active 2e-ORR catalysts. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a carbon-based catalyst with two tellurium coordination structures, its preparation method and application, so as to solve the technical problems that the catalysts used in the current production of hydrogen peroxide by 2e-ORR are expensive, have poor activity and are difficult to meet the actual production application requirements.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] This invention discloses a method for preparing a carbon-based catalyst having two tellurium coordination structures, comprising the following steps:

[0007] S1: Te powder and TeO2 powder are added to the graphene oxide suspension and subjected to an alcoholic reaction; after the reaction is completed, they are separated and dried to obtain a bulk gel.

[0008] S2: The bulk gel was subjected to chemical vapor deposition to obtain a carbon-based catalyst with two tellurium coordination structures.

[0009] Further, in S1, the concentration of the graphene oxide suspension is 2±0.1 mg / mL; the graphene oxide suspension is obtained by ultrasonically dispersing graphene oxide in anhydrous ethanol solution and mixing it by ultrasonication for 8-10 hours.

[0010] Furthermore, the mass ratios of the Te powder and the tellurium in the TeO2 powder to the graphene oxide are 1.5%-6% and 7%-14%, respectively.

[0011] Furthermore, the mass ratio of the Te powder to the graphene oxide is 1.5%; the mass ratio of tellurium in the TeO2 powder to the graphene oxide is 10.5%.

[0012] Furthermore, in S1, the temperature of the alcohol thermal reaction is 180-200℃, and the time is 12-24h.

[0013] Furthermore, in S1, the drying temperature is 30-80°C, and the drying time is not less than 8 hours.

[0014] Furthermore, in S2, the process parameters for the chemical vapor deposition process are:

[0015] After setting the temperature to 800-900℃, the gas flow rate to Ar: 100±5sccm, NH3: 50±5sccm, and the total gas pressure to 3.0±0.1Torr, the bulk gel was subjected to high-temperature nitriding treatment for 1-4 hours.

[0016] Furthermore, the temperature is 850°C, and the high-temperature nitriding treatment lasts for 2 hours.

[0017] The present invention also discloses a carbon-based catalyst with two tellurium coordination structures prepared by the above preparation method.

[0018] The present invention also discloses the application of the carbon-based catalyst having two tellurium coordination structures as a catalytic material in the electrocatalytic oxygen reduction reaction to synthesize hydrogen peroxide.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention discloses a method for preparing a carbon-based catalyst with two tellurium coordination structures. Two tellurium precursors with different structures—metallic Te powder and oxide TeO2—are reacted with graphene oxide (GO) under intense aldolothermic reaction conditions. Due to their different structures, their anchoring sites on graphene also differ. The chain structure of Te powder is more easily attached to the graphene edge, while the tetrahedral structure of TeO2 is more easily grafted onto the graphene surface. Simultaneously, the metalloid properties of Te itself make it easier to form a single-atom configuration on the graphene surface. Then, the introduced precursor coordination structures are further disrupted and modified under a high-temperature environment using chemical vapor deposition. In this process, the Te-O coordination structure in TeO2 is more largely retained, forming a single-atom catalyst with two tellurium coordination structures (Te / TeO2-NC). The numerous and uniformly dispersed active sites of this single-atom catalyst, along with the ability to modulate its electronic structure through Te coordination structure modification, significantly improve its catalytic activity for hydrogen peroxide production, ensuring a promising future for industrial production under long-term, high-current conditions. This method is simple and easy to operate. It only requires two synthesis steps, alcothermal synthesis and chemical vapor deposition, to prepare excellent 2e-ORR electrochemical catalysts in large quantities and reproducibly. Moreover, the precursors used in the preparation (elemental Te powder and oxide TeO2) are inexpensive and readily available, and the Te element has metal-like properties, which can form single-atom catalysts with better catalytic activity.

[0021] This invention also discloses a carbon-based catalyst with two tellurium coordination structures prepared by the above method. According to relevant experimental results, it not only exhibits high activity and high H2O2 selectivity in rotating ring-disk electrode testing, but also demonstrates high current density (500 mA / cm²) performance in a flow electrolyzer. 2 It has the excellent property of synthesizing H2O2 with high Faraday efficiency. Attached Figure Description

[0022] Figure 1 The XRD pattern of Te / TeO2-NC@1h prepared in Example 1 of this invention;

[0023] Figure 2 The infrared spectrum of Te / TeO2-NC@1h prepared in Example 1 of this invention;

[0024] Figure 3 This is a TEM image of Te / TeO2-NC@1h prepared in Example 1 of this invention;

[0025] Where: a - low magnification; b - high magnification;

[0026] Figure 4 The XRD pattern of Te / TeO2-NC@2h prepared in Example 2 of this invention;

[0027] Figure 5 The infrared spectrum of Te / TeO2-NC@2h prepared in Example 2 of this invention;

[0028] Figure 6 TEM image of Te / TeO2-NC@2h prepared in Example 2 of this invention;

[0029] Where: a - low magnification; b - high magnification;

[0030] Figure 7 The image shown is a HAADF-STEM image (spherical aberration electron microscope image) of Te / TeO2-NC@2h prepared in Example 2 of this invention.

[0031] Figure 8 XPS plot and elemental composition distribution of Te / TeO2-NC@2h prepared in Example 2 of this invention;

[0032] Where: a - XPS plot; b - element content;

[0033] Figure 9 XPS fine structure peaks of C1s of Te / TeO2-NC@2h prepared in Example 2 of this invention;

[0034] Figure 10 XPS fine structure peaks of O1s of Te / TeO2-NC@2h prepared in Example 2 of this invention;

[0035] Figure 11 XPS fine structure peaks of Te / TeO2-NC@2h prepared in Example 2 of this invention and some comparative samples of Te 3d;

[0036] Figure 12 The 2e-ORR performance diagram of the catalyst Te / TeO2-NC@2h prepared in Example 2 of this invention in the RRDE device;

[0037] Wherein: a- Polarization curve in 0.1M KOH electrolyte, scan rate 5mV / s; b- Tafel curve in 0.1M KOH electrolyte; c- H2O2 selectivity and ORR reaction electron transfer number curves; d- Stability test;

[0038] Figure 13The 2e–ORR performance of Te / TeO2-NC@2h prepared in Example 2 of this invention as a catalyst in an FC device is shown in the figure (the figure includes the VI curve of the sample in 0.1M KOH and the current density at different current densities (50, 200, 350, 500, 650, 800, 950 mA / cm). 2 Faraday efficiency under ( )

[0039] Figure 14 The Te / TeO2-NC@2h catalyst prepared in Example 2 of this invention was used as a catalyst in an FC device at 500 mA / cm². 2 Stability test in 0.1M KOH;

[0040] Figure 15 The XRD pattern of Te / TeO2-NC@4h prepared in Example 3 of this invention;

[0041] Figure 16 The infrared spectrum of Te / TeO2-NC@4h prepared in Example 3 of this invention;

[0042] Figure 17 This is a TEM image of Te / TeO2-NC@4h prepared in Example 3 of the present invention;

[0043] Where: a - low magnification; b - high magnification. Detailed Implementation

[0044] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0045] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0046] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0047] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0048] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0049] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0050] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0051] The graphene oxide in the following examples was prepared using the Hummers modified method. The specific preparation process is as follows: 3.0 g of graphite powder was dispersed in a concentrated H₂SO₄ / H₃PO₄ (360:40 mL) mixed solution (volume ratio 9:1) under an ice-water bath at 0°C. 18 g of KMnO₄ was slowly added while continuously stirring mechanically to oxidize the graphite powder and slowly release heat. The water bath temperature was then increased to 50°C and maintained for 12 hours. After the solution cooled to room temperature, it was poured into 400 mL of pre-prepared crushed ice and stirred continuously until completely dissolved. Then, 30% H₂O₂ was slowly added to remove the KMnO₄ from the solution until the solution turned bright yellow. Subsequently, the solution was separated by centrifugation, washed repeatedly with 30% HCl solution, deionized water, and diethyl ether, and vacuum dried for at least 24 hours to obtain graphene oxide.

[0052] Example 1

[0053] A method for preparing a carbon-based catalyst having two tellurium coordination structures includes the following steps:

[0054] S1: Graphene oxide prepared by the Hummer modified method was ultrasonically dispersed in anhydrous ethanol solution and ultrasonicated for 8 hours to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL.

[0055] The tellurium content in the tellurium precursor element Te and TeO2 was added to the prepared graphene oxide suspension according to a certain mass ratio with graphene oxide (the mass percentage of elemental Te was 1.5% and the mass percentage of TeO2 was 10.5%). The mixture was stirred for 2 hours and then placed in a polytetrafluoroethylene heating kettle for an alcoholic reaction at a reaction temperature of 180°C for 12 hours. After the reaction was completed, the kettle was removed and cooled naturally to room temperature. The supernatant was then separated, and the turbid liquid was placed in a vacuum drying oven and dried for 8 hours (60°C) to obtain a dried black block gel.

[0056] S2: Set the furnace temperature to 850℃, the gas flow rate to Ar: 100±5sccm, NH3: 50±5sccm, and the total gas pressure to 3.0±0.1Torr; place the prepared black bulk gel into the center of the tube furnace and nitrid it at high temperature for 1h to obtain a carbon-based catalyst (Te / TeO2-NC@1h) with two tellurium coordination structures.

[0057] like Figure 1 The image shows the XRD pattern of the sample Te / TeO2-NC@1h. The special crystal planes (002), (100), and (110) of graphene can be clearly seen in the figure. The strong diffraction peak of the (002) crystal plane indicates that the graphene has a large grain size on the c-axis. The appearance of the (100) and (110) crystal planes indicates that the graphene structure is curled. At the same time, there are no special diffraction peaks of the precursors Te and TeO2 in the spectrum, which indicates that the precursor structure is not destroyed during the reaction and is well doped into the graphene.

[0058] like Figure 2 The image shows the infrared spectrum of the sample Te / TeO2-NC@1h. The spectrum contains abundant oxygen functional groups, which is conducive to the 2e-ORR reaction. The presence of the stretching vibration peak of Te-O in the spectrum also indicates that the introduction of the precursor forms a Te-O coordination structure.

[0059] like Figure 3 a and Figure 3 Figure b shows low-magnification and high-magnification TEM images of the sample Te / TeO2-NC@1h. From... Figure 3 As can be seen, the graphene in this sample exhibits a distinct layered structure with abundant wrinkles, which is conducive to electrochemical reactions on the surface. Furthermore, in the high-magnification TEM image, the (002) crystal plane of the graphene can be observed, with an interlayer spacing of 0.37 nm, which is larger than the typical graphene interlayer spacing (0.34 nm). This is due to the introduction of TeO2 into the graphene interlayers, which expands the interlayer spacing.

[0060] Example 2

[0061] A method for preparing a carbon-based catalyst having two tellurium coordination structures includes the following steps:

[0062] S1: Graphene oxide prepared by the Hummer modified method was ultrasonically dispersed in anhydrous ethanol solution and ultrasonicated for 10 h to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL.

[0063] The tellurium content in the tellurium precursor element Te and TeO2 was added to the prepared graphene oxide suspension according to a certain mass ratio with graphene oxide (the mass percentage of elemental Te was 1.5% and the mass percentage of TeO2 was 10.5%). The mixture was stirred for 2 hours and then placed in a polytetrafluoroethylene heating kettle for an alcoholic reaction at a reaction temperature of 180°C for 12 hours. After the reaction was completed, the kettle was removed and cooled naturally to room temperature. The supernatant was then separated, and the turbid liquid was placed in a vacuum drying oven and dried for 8 hours (60°C) to obtain a dried black block gel.

[0064] S2: Set the furnace temperature to 850℃, the gas flow rate to Ar: 100±5sccm, NH3: 50±5sccm, and the total gas pressure to 3.0±0.1Torr; place the prepared black bulk gel into the center of the tube furnace and nitrid with high temperature for 2h to obtain a carbon-based catalyst with two tellurium coordination structures (Te / TeO2-NC@2h).

[0065] like Figure 4 The image shows the XRD pattern of the sample Te / TeO2-NC@2h. The special crystal planes (002), (100), and (110) of graphene are clearly visible. The strong diffraction peak of the (002) plane indicates a large grain size of graphene along the c-axis, while the appearance of the (100) and (110) planes suggests a curled graphene structure. Furthermore, the absence of special diffraction peaks for the precursors Te and TeO2 indicates that the precursor structure was not destroyed during the reaction, resulting in good doping within the graphene.

[0066] like Figure 5 The image shows the infrared spectrum of the sample Te / TeO2-NC@2h. The spectrum contains abundant oxygen functional groups, which is conducive to the 2e-ORR reaction. The presence of the stretching vibration peak of Te-O in the spectrum also indicates that the introduction of the precursor forms a Te-O coordination structure.

[0067] like Figure 6 a and Figure 6 Figure b shows low-magnification and high-magnification TEM images of the sample Te / TeO2-NC@2h. From... Figure 6As can be seen, the graphene in this sample exhibits a distinct layered structure with abundant wrinkles, which is conducive to electrochemical reactions on the surface. Furthermore, in the high-magnification TEM image, the (002) crystal plane of the graphene can be observed, with an interlayer spacing of 0.38 nm, which is larger than the typical graphene interlayer spacing (0.34 nm). This is because the introduction of TeO2 into the graphene interlayers expands the interlayer spacing.

[0068] like Figure 7 The image shown is a HAADF-STEM image of the sample Te / TeO2-NC@2h. The white bright spots in the image represent dispersed Te atoms, indicating that the doped Te exists in single-atom form, and that this catalyst is a single-atom catalyst.

[0069] like Figure 8 a and Figure 8 Figure b shows the XPS full spectrum of the sample Te / TeO2-NC@2h and the elemental content obtained from XPS calculation and ICP test, indicating that element Te was successfully introduced into graphene. The XPS and ICP calculations on element Te content show that the loading of introduced Te is about 4%, which is consistent with the single-atom loading of a single-atom catalyst.

[0070] like Figure 9 As shown, the XPS fine structure peaks of C1s in the sample Te / TeO2-NC@2h are shown. The clear Te-C peaks in the figure indicate the presence of Te-C coordination.

[0071] like Figure 10 As shown, the XPS fine structure peaks of O1s in the sample Te / TeO2-NC@2h are shown. The clear Te-O peaks in the figure indicate the presence of Te-O coordination.

[0072] like Figure 11 The figure shows the XPS fine structure peaks of the sample Te / TeO2-NC@2h and some comparative samples of Te 3d. The peaks in the figure are divided into Te-O and Te-C, indicating that Te forms coordination structures with C and O. Furthermore, compared with TeO2-NC@2h formed by adding only TeO2 and Te-NC@2h formed by adding only Te, it was found that the different precursors form Te coordination structures that influence each other, leading to a deviation in the Te-O peak position, which modulates the electronic structure and thus optimizes the 2e-ORR performance. In addition, there are no specific peaks for elemental Te and TeO2 in the Te 3d spectrum, indicating that the precursor structure is completely destroyed.

[0073] like Figure 12 The figure shows the 2e-ORR performance of the sample Te / TeO2-NC@2h under the RRDE device. Figure 12a is the polarization curve of Te / TeO2-NC@2h in 0.1M KOH electrolyte, with an initial potential of 0.81V (and a loop current of 0.1mA / cm). 2 (electric potential); Figure 12 b is the Te / TeO2-NC@2h graph, and is the Tafel curve with a slope of 84mV dec. -1 ; Figure 12 c is the H2O2 selectivity and ORR reaction electron transfer number curve of Te / TeO2-NC@2h. In the potential range of 0.15-0.65V, the H2O2 selectivity remains above 90%, and the electron transfer number is close to 2. Figure 12 d represents the stability test, in which the selectivity remained at around 92% throughout the 30-hour test. In summary, all the above results indicate that Te / TeO2-NC@2h has excellent 2e-ORR performance.

[0074] like Figure 13 As shown, this is the 2e catalyst of sample Te / TeO2-NC@2h in an FC device. - ORR performance graph; tested at 0.1M KOH, the stable VI curve indicates high current density (100mA / cm²). 2 There is a possibility of producing H2O2 under (around 50, 200, 350, 500, 650, 800, 950 mA cm⁻¹); at the same time, different current densities (50, 200, 350, 500, 650, 800, 950 mA cm⁻¹) were selected. -2 The FE was tested, and the results showed that FE remained at a high level (97.42-85.19%) within this current range.

[0075] like Figure 14 As shown, the sample Te / TeO2-NC@2h was used as a catalyst in an FC device at 500 mA / cm². 2 Stability tests showed that the catalyst had an ultra-long stability of 200 h under 0.1 M KOH, with an average H2O2 concentration of up to 1877 ppm and an average Faraday efficiency of over 90%, demonstrating its promising prospects for industrial electrocatalytic synthesis of H2O2.

[0076] Example 3

[0077] A method for preparing a carbon-based catalyst having two tellurium coordination structures includes the following steps:

[0078] S1: Graphene oxide prepared by the Hummer modified method was ultrasonically dispersed in anhydrous ethanol solution and ultrasonicated for 8 hours to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL.

[0079] The tellurium content in the tellurium precursor element Te and TeO2 was added to the prepared graphene oxide suspension according to a certain mass ratio with graphene oxide (the mass percentage of elemental Te was 1.5% and the mass percentage of TeO2 was 10.5%). The mixture was stirred for 2 hours and then placed in a polytetrafluoroethylene heating kettle for an alcoholic reaction at a reaction temperature of 180°C for 12 hours. After the reaction was completed, the kettle was removed and cooled naturally to room temperature. The supernatant was then separated, and the turbid liquid was placed in a vacuum drying oven and dried for 8 hours (60°C) to obtain a dried black block gel.

[0080] S2: Set the furnace temperature to 850℃, the gas flow rate to Ar: 100±5sccm, NH3: 50±5sccm, and the total gas pressure to 3.0±0.1Torr; Place the black bulk gel obtained in (2) into the center of the tube furnace and nitrid it at high temperature for 4h to obtain a carbon-based catalyst with two tellurium coordination structures (Te / TeO2-NC@4h).

[0081] like Figure 15 The image shows the XRD pattern of the sample Te / TeO2-NC@4h. The special crystal planes (002), (100), and (110) of graphene can be clearly seen in the figure. The strong diffraction peak of the (002) crystal plane indicates that the graphene has a large grain size on the c-axis. The appearance of the (100) and (110) crystal planes indicates that the graphene structure is curled. At the same time, there are no special diffraction peaks of the precursors Te and TeO2 in the spectrum, which indicates that the precursor structure is not destroyed during the reaction and is well doped into the graphene.

[0082] like Figure 16 The image shows the infrared spectrum of the sample Te / TeO2-NC@4h. The spectrum contains abundant oxygen functional groups, which is conducive to the 2e-ORR reaction. The presence of the stretching vibration peak of Te-O in the spectrum also indicates that the introduction of the precursor forms a Te-O coordination structure.

[0083] like Figure 17 a and Figure 17 Figure b shows the low-magnification and high-magnification TEM images of the sample Te / TeO2-NC@4h; from Figure 3 As can be seen, the graphene in this sample exhibits a distinct layered structure with abundant wrinkles, which is conducive to electrochemical reactions on the surface. In addition, in the high-magnification TEM image, the (002) crystal plane of the graphene can be observed, and the interlayer spacing of 0.38 nm is larger than that of typical graphene interlayer spacing (0.34 nm). This is because TeO2 is introduced into the interlayer of graphene, which expands the interlayer spacing.

[0084] Example 4

[0085] A method for preparing a carbon-based catalyst having two tellurium coordination structures includes the following steps:

[0086] S1: Graphene oxide prepared by the Hummer modified method was ultrasonically dispersed in anhydrous ethanol solution and ultrasonicated for 8 hours to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL.

[0087] The tellurium content in the tellurium precursor element Te and TeO2 was added to the prepared graphene oxide suspension according to a certain mass ratio with graphene oxide (the mass percentage of elemental Te was 1.5% and the mass percentage of TeO2 was 14%). The mixture was stirred for 2 hours and then placed in a polytetrafluoroethylene heating kettle for an alcoholic reaction at a reaction temperature of 180°C for 12 hours. After the reaction was completed, the kettle was removed and cooled naturally to room temperature. The supernatant was then separated, and the turbid liquid was placed in a vacuum drying oven and dried for 8 hours (60°C) to obtain a dried black block gel.

[0088] The furnace temperature was set at 850℃, the gas flow rate was Ar: 100±5 sccm, NH3: 50±5 sccm, and the total gas pressure was 3.0±0.1 Torr. The prepared black bulk gel was placed in the center of the tube furnace and subjected to high-temperature nitriding treatment for 2 hours to obtain a carbon-based catalyst with two tellurium coordination structures.

[0089] Example 5

[0090] A method for preparing a carbon-based catalyst having two tellurium coordination structures includes the following steps:

[0091] S1: Graphene oxide prepared by the Hummer modified method was ultrasonically dispersed in anhydrous ethanol solution and ultrasonicated for 8 hours to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL.

[0092] The tellurium content in the tellurium precursor element Te and TeO2 was added to the prepared graphene oxide suspension according to a certain mass ratio with graphene oxide (the mass percentage of elemental Te was 4.5% and the mass percentage of TeO2 was 10.5%). The mixture was stirred for 2 hours and then placed in a polytetrafluoroethylene heating vessel for an alcoholic reaction at a reaction temperature of 180°C for 12 hours. After the reaction was completed, the vessel was removed and cooled naturally to room temperature. The supernatant was then separated, and the turbid liquid was placed in a vacuum drying oven and dried for 8 hours (60°C) to obtain a dried black block gel.

[0093] S2: Set the furnace temperature to 850℃, the gas flow rate to Ar: 100±5sccm, NH3: 50±5sccm, and the total gas pressure to 3.0±0.1Torr; place the prepared black bulk gel into the center of the tube furnace and nitrid it at high temperature for 2 hours to obtain a carbon-based catalyst with two tellurium coordination structures.

[0094] Application Examples

[0095] This invention describes the application of a carbon-based catalyst with two tellurium coordination structures for the electrocatalytic oxygen reduction synthesis of hydrogen peroxide. The catalytic reaction application tests were conducted on a Pine Rotating Ring-Disk Electrode (RRDE; electrode model: AFE6R2) and a three-phase flow cell. The RRDE tests were performed on a CHI760E electrochemical workstation, while the flow cell tests were performed on a CHI1140C electrochemical workstation. An electrode dispersion (2 mg catalyst, 200 μL water, 200 μL ethanol, 40 μL Nafion solution) was prepared by mixing 2 mg of the prepared electrocatalyst with water, ethanol, and 5 wt% Nafion solution in a volume ratio of 5:5:1. 5 μL of this electrode dispersion was then evenly drop-coated onto the RRDE surface in two portions and dried for at least 24 hours to serve as the working electrode, with a loading of 0.1 mg / cm³. 2 The area of ​​the disk is 0.2376 cm². 2 The area of ​​the platinum ring is 0.2356 cm². 2 The catalytic process of RRDE was carried out in a 0.1M KOH aqueous solution saturated with O2. A three-electrode system was used for testing, with a platinum wire as the counter electrode, an Ag / AgCl (saturated potassium chloride) electrode as the reference electrode, and the RRDE coated with the prepared catalyst as the working electrode. Linear sweep voltammetry (LSV) was used at a scan rate of 5 mV / s, with the loop current collection voltage set at 1.2 V and the current collection voltage set at 0.40 V for stability testing. The RRDE rotation speed was 1600 rpm. In the FC device, the cathode was prepared by uniformly dropping 55 μL of the prepared electrode dispersion twice onto a 1*1 cm plate. 2 It was dried on a gas diffusion layer (Sigracet 29BC) with a catalyst loading of 0.25 mg / cm³. 2 During the test, O2 reached the gas diffusion layer at a flow rate of 10 sccm, and further diffused into the cathode chamber, reacting with the flowing (162 ml / h) alkaline solution (0.1 MkOH) to generate H2O2. Simultaneously, the anolyte (48 mL / h) H2SO4 underwent an OER reaction to produce H2O. + The H₂O₂ solution passes through the proton exchange membrane (PEM) and reaches the cathode chamber, completing the electrolysis reaction. The Faradaic efficiency (FE) at the corresponding current can be calculated by titrating the concentration of the collected H₂O₂ solution with potassium permanganate. Different current densities (50, 200, 350, 500, 650, 800, 950 mA / cm²) were selected here. 2 Faraday efficiency (FE) was tested; all potentials were replaced with standard hydrogen electrode (RHE): E(RHE) = E(Ag / AgCl) + 0.059 × pH + 0.1976.

[0096] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a carbon-based catalyst having two tellurium coordination structures, characterized in that, Includes the following steps: S1: Te powder and TeO2 powder are added to the graphene oxide suspension and subjected to an alcoholic reaction; after the reaction is completed, they are separated and dried to obtain a bulk gel. The concentration of the graphene oxide suspension is 2 ± 0.1 mg / mL; the graphene oxide suspension is obtained by ultrasonically dispersing graphene oxide in anhydrous ethanol solution and mixing by ultrasonication for 8-10 h; the mass ratio of Te powder, the mass ratio of tellurium in TeO2 powder to graphene oxide is 1.5%-6%, and the mass ratio of Te powder to graphene oxide is 7%-14%; the mass ratio of Te powder to graphene oxide is 1.5%; the mass ratio of tellurium in TeO2 powder to graphene oxide is 10.5%. S2: The bulk gel is subjected to chemical vapor deposition to obtain a carbon-based catalyst with two tellurium coordination structures; the process parameters for the chemical vapor deposition are as follows: After setting the temperature to 800-900 ℃, the gas flow rate to Ar: 100 ± 5 sccm, NH3: 50 ± 5 sccm, and the total gas pressure to 3.0 ± 0.1 Torr, the bulk gel was subjected to high-temperature nitriding treatment for 1-4 h; the temperature was 850 ℃, and the high-temperature nitriding treatment was carried out for 2 h.

2. The method for preparing a carbon-based catalyst having two tellurium coordination structures according to claim 1, characterized in that, In S1, the temperature of the alcohol thermal reaction is 180-200 °C, and the time is 12-24 h.

3. The method for preparing a carbon-based catalyst having two tellurium coordination structures according to claim 1, characterized in that, In S1, the drying temperature is 30-80 ℃ and the time is not less than 8 h.

4. A carbon-based catalyst having two tellurium coordination structures, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 3.

5. The application of the carbon-based catalyst having two tellurium coordination structures as described in claim 4, characterized in that, The carbon-based catalyst with two tellurium coordination structures is used as a catalytic material in the electrocatalytic oxygen reduction reaction to synthesize hydrogen peroxide.

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