Carbon-based catalyst with two Zr phase structures as well as preparation method and application of carbon-based catalyst

Abstract

The invention discloses a two-electron oxygen reduction carbon-based catalyst with two Zr phase structures and a preparation method and application thereof, and belongs to the technical field of electrochemical catalysis. According to the method, an alcohol-dispersed precursor ZrCl4 is used as a Zr source, and free Zr ions are combined with oxygen functional groups on graphene oxide (GO) in the alcohol heating process; then, through the chemical vapor deposition (CVD) process, due to the oxygen distribution degree on GO, Zr is gathered in a local oxygen-rich area to form crystals, and isolated Zr forms monatomic sites. According to the Zr-Zr7O11N2 / NC catalyst obtained by the method, through the synergistic effect of the two structures, the activity of catalyzing the generation of hydrogen peroxide is greatly improved; the high-performance hydrogen peroxide electrocatalyst is synthesized through alcohol heating and chemical vapor deposition methods, the method is simple, raw materials are cheap and easy to obtain, and the carbon-based catalyst has high electrocatalytic activity, hydrogen peroxide selectivity and stability under a 0.1 M KOH alkaline solution test and is a non-noble metal catalyst with good industrial application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic chemistry, and particularly relates to a carbon-based catalyst with two Zr phase structures, a preparation method thereof, and an application thereof. Background Art

[0002] As a core electrochemical process in energy conversion and storage systems, the precise regulation of the reaction pathway of the oxygen reduction reaction (ORR) is the key to determining the energy conversion efficiency and application scenarios. There are two main pathways in ORR thermodynamics: the four-electron transfer pathway (4e-ORR) directly reduces oxygen to water and is the basic reaction of high-efficiency energy devices such as fuel cells; while the two-electron transfer pathway (2e-ORR) generates H2O2 through incomplete oxygen reduction. This green oxidant has irreplaceable application values in the fields of environmental remediation, medical disinfection, and chemical synthesis. Compared with the high energy consumption and complex process of the traditional anthraquinone method for producing H2O2, the electrocatalytic 2e-ORR technology is regarded as an ideal solution for the production of the new generation of H2O2 due to its environmental friendliness and flexible operation. However, the large-scale application of this technology is limited by the insufficient selectivity and stability challenges of catalytic materials: although noble metal-based catalysts can achieve high selectivity, their scarcity and toxicity restrict practical applications; although non-metallic carbon-based materials have low costs, they are limited by the low density of active sites and the difficulty of electron structure regulation, and it is difficult to maintain high selectivity within a wide potential window. Therefore, the development of new 2e-ORR catalysts with high activity, high selectivity, and long-term stability has become the core topic for promoting the industrialization of the electrochemical synthesis of H2O2 technology.

[0003] Due to their adjustable electronic structures, high electrical conductivities, and rich surface chemical sites, carbon-based materials have become an important candidate system for 2e-ORR catalysts. By heteroatom doping (such as nitrogen, boron) or defect engineering, the charge distribution of the carbon skeleton can be regulated, and the adsorption free energy of the *OOH intermediate can be optimized, thereby improving the selectivity of H2O2. However, traditional carbon-based catalysts still face challenges such as low density of active sites and insufficient stability caused by metal aggregation. In addition, under strong oxidizing or extreme pH conditions, the corrosion problem of the carbon matrix also limits its long-term operation efficiency. Therefore, the development of carbon-based catalysts with high activity, high stability, and low cost has become a research hotspot in this field. Summary of the Invention

[0004] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a carbon-based catalyst with two Zr phase structures, a preparation method thereof, and an application thereof, so as to solve the technical problems that the catalysts used for producing hydrogen peroxide through 2e-ORR at present are expensive, not outstanding in activity, and difficult to meet the actual production applications.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention discloses a preparation method of a carbon-based catalyst with two Zr phase structures, comprising the following steps:

[0007] S1: Add ZrCl4 to the graphene oxide suspension and carry out solvothermal reaction; after the reaction is completed, separate and dry in sequence to obtain a bulk gel;

[0008] S2: Carry out chemical vapor deposition treatment on the bulk gel to obtain a carbon-based catalyst with two Zr phase structures.

[0009] Further, in S1, the precursor ZrCl4 is dispersed in ethanol.

[0010] Further, 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 an anhydrous ethanol solution and mixing for 8 - 10 h.

[0011] Further, the mass ratio of Zr in ZrCl4 to the mass of graphene oxide is 1 - 9%.

[0012] Further, in S1, the temperature of the solvothermal reaction is 180 °C and the time is 12 - 18 h.

[0013] Further, in S1, the drying temperature is 60 °C and the time is not less than 2 - 4 h.

[0014] Further, in S2, the process parameters of the chemical vapor deposition treatment are:

[0015] Set the temperature to 700 - 900 °C, the gas flow rate is Ar: 100 ± 5 sccm, NH3: 50 ± 5 sccm, and the total pressure is 3.0 ± 0.1 Torr, then carry out high-temperature nitridation treatment on the bulk gel for 1 - 3 h.

[0016] The present invention also discloses a carbon-based catalyst with two Zr phase structures prepared by the above preparation method.

[0017] The present invention also discloses the application of the above carbon-based catalyst with two Zr phase structures, and the carbon-based catalyst with two Zr phase structures is used as a catalytic material in the electrocatalytic oxygen reduction synthesis of hydrogen peroxide reaction.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The preparation method of the carbon-based catalyst with two Zr phase structures disclosed by the present invention. First, use ZrCl4 as a precursor, first disperse it in ethanol to inhibit its hydrolysis to form ZrO 2+Structure. During the solvothermal process, Zr is anchored on GO, while free Zr ions can only bond to the oxygen functional groups of GO. However, there is a problem of uneven local oxygen distribution in GO, which further leads to different distributions of Zr. Therefore, in the subsequent CVD nitridation process, the oxygen-rich regions are prone to aggregation to form crystal phases due to the presence of more Zr, while in the regions with less oxygen content, isolated Zr forms nitrogen-oxygen coordination to form single atoms. And if the Zr precursor undergoes hydrolysis, ZrO 2+ can be connected to the carbon of the graphene structure through oxygen to make the Zr distribution uniform and only form crystal phases. Through the above method, a catalyst (Zr-Zr7O 11 N2 / NC) with two Zr phases can be loaded on the carbon material. This composite catalyst not only has numerous Zr atomic sites as reaction sites, but also can control the crystal phase size of Zr7O 11 N2 to effectively form a synergistic effect with single-atom sites, thereby improving the 2e-ORR activity. It is a material with broad industrial application prospects. This method is simple and easy to operate, and excellent 2e-ORR carbon-based catalysts can be prepared in large quantities and reproducibly only through two synthesis steps of solvothermal and chemical vapor deposition; moreover, the preparation precursor used is a cheap and easily available metal compound, and its content in the earth's crust is much higher than that of other noble metal elements.

[0020] The present invention also discloses the application of a carbon-based catalyst with two Zr phase structures prepared by the above preparation method. According to relevant experimental results, it not only shows high activity and high H2O2 selectivity in the rotating ring-disk electrode test, but also shows excellent H2O2 production capacity in H-type electrolytic cells and flow electrolytic cells. Description of the Drawings

[0021] Figure 1 Shown is the infrared absorption spectrum of the carbon-based catalyst Zr-Zr7O 11 N2 / NC-5 with two Zr phase structures prepared in Example 3;

[0022] Figure 2 Shown is the XRD pattern of the carbon-based catalyst Zr-Zr7O 11 N2 / NC-5 with two Zr phase structures prepared in Example 3;

[0023] Figure 3 Shown in a and 3b are the low-magnification transmission electron microscopy and selected area electron diffraction patterns of the carbon-based catalyst Zr-Zr7O 11 N2 / NC-5 with two Zr phase structures prepared in Example 3;

[0024] Figure 4 Shown is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 311 High-magnification TEM image of N2 / NC-5;

[0025] Figure 5 As shown in Figures 5a and 5b, the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3; 11 Aberration-corrected electron microscopy and energy-dispersive X-ray spectroscopy elemental mapping images of N2 / NC-5;

[0026] Figure 6 As shown in Figures 6a and 6b, the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3; 11 XPS survey spectrum and corresponding elemental contents of N2 / NC-5;

[0027] Figure 7 As shown, the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3; 11 XPS fine spectrum of C1s of N2 / NC-5;

[0028] Figure 8 As shown in Figures 8a and 8b, the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3; 11 XPS fine spectra of N1s and O1s of N2 / NC-5;

[0029] Figure 9 As shown, the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3; 11 XPS fine spectrum of Zr3d of N2 / NC-5;

[0030] Figure 10 As shown, the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3; 11 Test results of N2 / NC-5 in RRDE; where: a - polarization curve in 0.1 M KOH electrolyte with a scan rate of 5 mV / s;; c - H2O2 selectivity and ORR reaction electron transfer number curve;;

[0031] Figure 11 As shown, the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3; 11 Test results of N2 / NC-5 in an H-type electrolytic cell; where: a - stability test at current densities of 10, 20, 30, 40, 50 mA / cm 2 ; b - FE and H2O2 concentration at the corresponding current density;

[0032] Figure 12 As shown, the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3;11 Test results of N2 / NC-5 in flow electrolysis cell. Where: a-at 50, 100, 150, 200, 250 mA / cm 2 Corresponding FE; b-at 250mA / cm 2 The stability test. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0034] The graphene oxide in the following embodiment is prepared by the Hummers modified method, and the specific preparation process is as follows: in an ice water bath at 0°C, 3.0g of graphite powder is dispersed in a mixed solution of concentrated H2SO4 / H3PO4 (360:40mL) with a volume ratio of 9:1, 18g of KMnO4 is slowly added and mechanically stirred continuously to oxidize the graphite powder and slowly release heat, and then the water bath temperature is increased to 50°C and maintained for 12h; after the solution is cooled to room temperature, it is poured into 400mL of crushed ice prepared in advance, stirred continuously until completely dissolved, and then H2O2 (30%) is slowly added to remove KMnO4 in the solution until the solution presents a bright yellow color. Subsequently, it is centrifuged, washed repeatedly with a mass concentration of 30% HCl solution, deionized water and ether, and vacuum dried for more than 24h to obtain graphene oxide.

[0035] Example 1

[0036] A method for preparing a carbon-based catalyst having two Zr phase structures comprises the following steps:

[0037] S1: Ultrasonic dispersion of graphene oxide prepared by Hummer's improved method in anhydrous ethanol solution for 8 hours to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL; ZrCl4 was dispersed in an ethanol solution, 10 μL (wherein the mass ratio of the precursor Zr element to GO was 1%) was added to the prepared graphene oxide suspension, stirred for 2 hours, and then placed in a polytetrafluoroethylene heating kettle for alcohol thermal reaction at a reaction temperature of 180°C for a reaction time of 12 hours. After the reaction was completed, the kettle was taken out and cooled naturally to room temperature, and then the supernatant was separated, and the lower turbid liquid was placed in a vacuum drying oven for 2 hours (60°C) to obtain a dry black block gel;

[0038] S2: The furnace temperature was set to 900°C, the gas flow rate was Ar: 100±5sccm, NH3: 50±5sccm, and the total gas pressure was 3.0±0.1Torr; the obtained black block gel was placed in the center of the tubular furnace and subjected to high-temperature nitridation treatment for 3h to obtain a carbon-based catalyst with two Zr phase structures (Zr-Zr7O 11 N2 / NC-1).

[0039] Example 2

[0040] A preparation method of a carbon-based catalyst with two Zr phase structures, comprising the following steps:

[0041] S1: Ultrasonically disperse graphene oxide prepared by the improved Hummer method in an anhydrous ethanol solution for 8 h to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL; Disperse ZrCl4 in an ethanol solution, take 10 μL (where the mass ratio of the precursor Zr element to GO is 3%) and add it to the prepared graphene oxide suspension, stir for 2 h, then place it in a polytetrafluoroethylene heating kettle for solvothermal reaction. The reaction temperature is 180 °C and the reaction time is 12 h. After the reaction is completed, take out the kettle and cool it naturally to room temperature. Subsequently, separate the supernatant, and place the lower turbid liquid in a vacuum drying oven to dry for 2 h (60 °C) to obtain a dried black bulk gel;

[0042] S2: Set the furnace temperature to 900 °C, the gas flow rate to Ar: 100 ± 5 sccm, NH3: 50 ± 5 sccm, and the total pressure to 3.0 ± 0.1 Torr; Place the prepared black bulk gel in the center of a tubular furnace and perform high-temperature nitridation treatment for 3 h to obtain a carbon-based catalyst with two Zr phase structures (Zr-Zr7O 11 N2 / NC-3).

[0043] Example 3

[0044] A preparation method of a carbon-based catalyst with two Zr phase structures, comprising the following steps:

[0045] S1: Ultrasonically disperse graphene oxide prepared by the improved Hummer method in an anhydrous ethanol solution for 8 h to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL; Disperse ZrCl4 in an ethanol solution, take 10 μL (where the mass ratio of the precursor Zr element to GO is 5%) and add it to the prepared graphene oxide suspension, stir for 2 h, then place it in a polytetrafluoroethylene heating kettle for solvothermal reaction. The reaction temperature is 180 °C and the reaction time is 12 h. After the reaction is completed, take out the kettle and cool it naturally to room temperature. Subsequently, separate the supernatant, and place the lower turbid liquid in a vacuum drying oven to dry for 2 h (60 °C) to obtain a dried black bulk gel;

[0046] S2: Set the furnace temperature to 900 °C, the gas flow rate to Ar: 100 ± 5 sccm, NH3: 50 ± 5 sccm, and the total pressure to 3.0 ± 0.1 Torr; Place the prepared black bulk gel in the center of a tubular furnace and perform high-temperature nitridation treatment for 3 h to obtain a carbon-based catalyst with two Zr phase structures (Zr-Zr7O 11 N2 / NC-5).

[0047] Example 4

[0048] A preparation method of a carbon-based catalyst with two Zr phase structures, comprising the following steps:

[0049] S1: Ultrasonically disperse graphene oxide prepared by the improved Hummer method in an anhydrous ethanol solution for 8 h to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL; Disperse ZrCl4 in an ethanol solution, take 10 μL (where the mass ratio of the precursor Zr element to GO is 7%) and add it to the prepared graphene oxide suspension, stir for 2 h, then place it in a polytetrafluoroethylene heating kettle for solvothermal reaction. The reaction temperature is 180 °C and the reaction time is 12 h. After the reaction is completed, take out the kettle and cool it naturally to room temperature. Subsequently, separate the supernatant, and place the lower turbid liquid in a vacuum drying oven to dry for 2 h (60 °C) to obtain a dried black bulk gel;

[0050] S2: Set the furnace temperature to 900 °C, the gas flow rate to Ar: 100 ± 5 sccm, NH3: 50 ± 5 sccm, and the total gas pressure to 3.0 ± 0.1 Torr; Place the prepared black bulk gel in the center of a tubular furnace and perform high-temperature nitridation treatment for 3 h to obtain a carbon-based catalyst with two Zr phase structures (Zr-Zr7O 11 N2 / NC-7).

[0051] Example 5

[0052] A preparation method of a carbon-based catalyst with two Zr phase structures, comprising the following steps:

[0053] S1: Ultrasonically disperse graphene oxide prepared by the improved Hummer method in an anhydrous ethanol solution for 8 h to obtain a uniform suspension with a graphene oxide concentration of 2 mg / mL; Disperse ZrCl4 in an ethanol solution, take 10 μL (where the mass ratio of the precursor Zr element to GO is 9%) and add it to the prepared graphene oxide suspension, stir for 2 h, then place it in a polytetrafluoroethylene heating kettle for solvothermal reaction. The reaction temperature is 180 °C and the reaction time is 12 h. After the reaction is completed, take out the kettle and cool it naturally to room temperature. Subsequently, separate the supernatant, and place the lower turbid liquid in a vacuum drying oven to dry for 2 h (60 °C) to obtain a dried black bulk gel;

[0054] S2: Set the furnace temperature to 900 °C, the gas flow rate to Ar: 100 ± 5 sccm, NH3: 50 ± 5 sccm, and the total gas pressure to 3.0 ± 0.1 Torr; Place the prepared black bulk gel in the center of a tubular furnace and perform high-temperature nitridation treatment for 3 h to obtain a carbon-based catalyst with two Zr phase structures (Zr-Zr7O 11 N2 / NC-9).

[0055] Application Example

[0056] The present invention describes the application of a carbon-based catalyst for electrocatalytic oxygen reduction to synthesize hydrogen peroxide with two Zr phase structures. The catalytic reaction application tests were carried out on an American Pine rotating ring-disk electrode device (Rotating ring-disk electrode, RRDE; electrode model: AFE6R2) and a three-phase flow electrolytic cell (Flow cell) respectively. Among them, the RRDE test was carried out on a CHI760E electrochemical workstation, while the Flow cell test used a CHI1140C electrochemical workstation. Take 2 mg of the prepared electrocatalyst and configure an electrode dispersion liquid according to the volume ratio of 5:5:1 with water, ethanol, and Nafion (5 wt%) solution (2 mg catalyst, 200 μL water, 200 μL ethanol, 40 μL Nafion solution). Take 5 μL of the electrode dispersion liquid and evenly drop-coat it on the surface of the RRDE in two times, and dry it for at least 24 h to be used as the working electrode, with a loading of 0.1 mg / cm 2 , and the disk area is 0.2376 cm 2 , and the platinum ring area is 0.2356 cm 2 ; The catalytic process of RRDE is carried out in a 0.1 M KOH aqueous solution saturated with O2. A platinum wire is used as the counter electrode, an Ag / AgCl (saturated potassium chloride) electrode is used as the reference electrode, and the RRDE coated with the prepared catalyst is used as the working electrode to form a three-electrode system for testing. Linear sweep voltammetry (LSV) is tested at a scanning rate of 5 mV / s, the ring current collection voltage is set at 1.2 V, the current collection voltage for the stability test is set at 0.40 V, and the RRDE rotation speed is 1600 rpm. When testing in an H-type electrolytic cell, the catalyst dispersion liquid is loaded on a 1*1 carbon paper (Sigracet29BC) with a loading of 0.25 mg / cm 2 . The catholyte uses 30 ml of 1 M KOH, the anode uses 30 ml of 0.5 M H2SO4, and they are separated by a nafion 117 membrane in the middle. A 1 h stability test is carried out at (10, 20, 30, 40, 50 mA / cm 2 ), and the relevant Faraday efficiency and H2O2 production are calculated. In the flow electrolytic cell device, the cathode is prepared by evenly drop-coating 55 μL of the above-prepared electrode dispersion liquid on a 2*2 cm 2 gas diffusion layer in two times and drying it, with a catalyst loading of 0.25 mg / cm 2; During the test, O2 reaches the gas diffusion layer at a flow rate of 50 sccm, and further diffuses into the cathode chamber to react with the flowing (162 ml / h) alkaline solution (1 M KOH) to generate H2O2. At the same time, the anolyte (162 mL / h) of 0.5 M H2SO4 undergoes an OER reaction to produce H + passes through the proton exchange membrane (PEM) to reach the cathode chamber to form a complete electrolysis reaction; then, by titrating the concentration of the collected H2O2 solution with potassium permanganate, the Faraday efficiency (FE) at the corresponding current can be calculated. Here, different current densities (50, 100, 150, 200, 250 mA / cm 2 ) were used to test the Faraday efficiency (FE); all potentials were converted to the standard hydrogen electrode (RHE): E(RHE) = E(Ag / AgCl) + 0.059 × pH + 0.1976.

[0057] After testing, Example 3 has high H2O2 selectivity and strong H2O2 production capacity. The selectivity in the RRDE test can reach up to 98.61%, and in the flow electrolytic cell, the concentration of electro-synthesized H2O2 is 3471 ppm at 250 mA / cm 2 .

[0058] Figure 1 Shown is the infrared absorption spectrum of the carbon-based catalyst Zr-Zr7O 11 N2 / NC-5 prepared in Example 3. In the figure, the absorption peaks of C-H, C-OH, C═C, C-O, etc. retained by the basic structure of graphene can be clearly seen, determining that the basic structure of the material is graphene oxide.

[0059] Figure 2 Shown is the XRD pattern of the carbon-based catalyst Zr-Zr7O 11 N2 / NC-5 prepared in Example 3. The two broad diffraction peaks near 26° and 44° can be attributed to the (002) and (100) crystal planes of graphene, and the diffraction peaks appearing at 30.2°, 50.7°, and 59.1° can be attributed to the nanocrystal Zr7O 11 N2, indicating that the doped Zr forms crystals loaded on the NC substrate.

[0060] Figure 3 Figures 3a and 3b show the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11Low-magnification transmission electron microscopy and selected area electron diffraction patterns of N2 / NC-5. In the transmission electron microscopy image, it can be clearly seen that graphene exhibits an obvious layered structure with abundant wrinkles, but there are still small black dots of tiny crystals locally. In the selected area electron diffraction pattern, only the special diffraction pattern of graphene exists, indicating that the formed crystal structure is small in quantity and distribution.

[0061] Figure 4 Shown is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11 High-magnification TEM image of N2 / NC-5. It can be clearly seen that there are tiny nanocrystals embedded in the graphene structure, further proving the previous characterization results.

[0062] Figure 5 As shown in a and 5b is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11 Aberration-corrected electron microscopy and energy-dispersive X-ray spectroscopy elemental mapping of N2 / NC-5. In Figure 5 a, it can be clearly seen that single atoms are distributed around the crystals, indicating that there are two phases in the synthesized sample: Zr nitride crystals and Zr single atoms. And in Figure 5 b, it can be seen that there is an overlapping phenomenon in the distribution of Zr and O elements, indicating that Zr is more likely to combine with the oxygen on GO.

[0063] Figure 6 As shown in a and 6b is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11 XPS full spectrum and corresponding element contents of N2 / NC-5. In Figure 6 a, it further shows that the element composition is C, N, O, Zr, and the Zr content measured by ICP is 7.6% higher than the Zr content used in the synthesis, indicating that Zr is easily introduced into the substrate.

[0064] Figure 7 Shown is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11 XPS fine spectrum of C1s of N2 / NC-5. In the figure, it can be seen that only the basic C coordination bonds of GO exist, indicating that Zr does not coordinate with C.

[0065] Figure 8 As shown in a and 8b is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11XPS fine spectra of N1s and O1s of N2 / NC-5. By combining the two spectra, it can be known that the coordination structure of Zr is Zr-O and N-Zr-O, and there is no direct Zr-N structure, which further illustrates that Zr element forms Zr-O structure first and then nitrides during the introduction process.

[0066] Figure 9 Shown is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11 XPS fine spectrum of Zr3d of N2 / NC-5. The Zr-O and N-Zr-O structures exist in the figure, which is consistent with the previous results.

[0067] Figure 10 Shown is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11 Test results of N2 / NC-5 in RRDE. Figure 910a is Zr-Zr7O 11 Polarization curve of N2 / NC-5 in 0.1 M KOH electrolyte, with the initial potential of 0.77 V (at the potential of the ring current of 0.1 mA / cm 2 ). In Figure 10 b, Zr-Zr7O 11 The calculated hydrogen peroxide selectivity of N2 / NC-5 in the potential range of 0.1 - 0.7 V is higher than 90%, and the highest can reach 98.61% at 0.63 V. In addition, its electron transfer number is also close to 2. In short, the above data indicate that Zr-Zr7O 11 N2 / NC-5 is a highly active 2e-ORR catalyst.

[0068] Figure 11 Shown is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11 Test results of N2 / NC-5 in H-type electrolytic cell. Figure 11 a is Zr-Zr7O 11 Stability test of N2 / NC-5 material for 3600 s at different current densities, Figure 11 b is the corresponding Faraday efficiency and hydrogen peroxide concentration. Although the FE decreases due to the trend of potential drop with the increase of current, overall, Zr-Zr7O 11 N2 / NC-5 catalyst maintains a good H2O2 production capacity. Operating at 50 mA for 1 h can obtain 30 ml of hydrogen peroxide at 770 ppm, showing excellent application prospects.

[0069] Figure 12 Shown is the carbon-based catalyst Zr-Zr7O with two Zr phase structures prepared in Example 3 11Test results of N2 / NC-5 in a flow electrolytic cell. In Figure 12 a, Zr-Zr7O 11 N2 / NC-5 has a high FE at current densities of 50, 100, 150, 200, and 250 mA / cm 2 , and even has an FE of 88.73% at a high current of 250 mA / cm 2 . And Figure 12 in b, Zr-Zr7O 11 N2 / NC-5 still maintains an FE of about 88% when operating at 250 mA / cm 2 for 20 h, and at the same time, 3240 ml of hydrogen peroxide with a concentration of 3471 ppm can be obtained, demonstrating a strong H2O2 production capacity.

Claims

1. A preparation method of a two-electron oxygen reduction carbon-based catalyst with two Zr phase structures, characterized in that, It includes the following steps: S1: Add ZrCl4 into the graphene oxide suspension and carry out solvothermal reaction; after the reaction is completed, carry out separation and drying treatments in sequence to obtain a bulk gel; S2: Carry out chemical vapor deposition treatment on the bulk gel to obtain a carbon-based catalyst with two Zr phase structures.

2. The preparation method of the carbon-based catalyst with two Zr phase structures according to claim 1, characterized in that, In S1, the precursor ZrCl4 is dispersed in ethanol.

3. The preparation method of the carbon-based catalyst with two Zr phase structures according to claim 1, characterized in that, The concentration of the graphene oxide suspension is 2 ± 0.1 mg / mL, and the graphene oxide suspension is obtained by ultrasonically dispersing graphene oxide in an absolute ethanol solution and mixing for 8 - 10 h.

4. The preparation method of a carbon-based catalyst with two Zr phase structures according to claim 3, characterized in that, The mass ratio of Zr in the ZrCl4 to the mass of graphene oxide is 1 - 9%.

5. The preparation method of the carbon-based catalyst with two Zr phase structures according to claim 1, characterized in that, In S1, the temperature of the solvothermal reaction is 180 °C and the time is 12 - 18 h.

6. The preparation method of the carbon-based catalyst with two Zr phase structures according to claim 1, characterized in that, In S1, the temperature of the drying is 60 °C and the time is not less than 2 - 4 h.

7. The preparation method of the carbon-based catalyst with two Zr phase structures according to claim 1, characterized in that, In S2, the process parameters of the chemical vapor deposition treatment are as follows: After setting the temperature to 700 - 900 °C, the gas flow rates are Ar: 100 ± 5 sccm, NH3: 50 ± 5 sccm, and the total gas pressure is 3.0 ± 0.1 Torr, then carry out high-temperature nitridation treatment on the bulk gel for 1 - 3 h.

8. A carbon-based catalyst with two Zr phase structures, characterized in that, It is prepared by using the preparation method described in any one of claims 1 - 7.

9. Use of the carbon-based catalyst with two Zr phase structures according to claim 8, characterized in that, The carbon-based catalyst with two Zr phase structures is used as a catalytic material in the electrocatalytic oxygen reduction reaction for synthesizing hydrogen peroxide.

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