A carbon-coated bismuth-tantalum oxide heterojunction catalyst, a preparation method and application thereof

Abstract

This invention discloses a carbon-coated bismuth-tantalum oxide heterojunction catalyst, its preparation method, and its application. The invention aims to address the problems of product selectivity, catalytic activity, and stability in existing metal-organic framework derivative-based catalysts. The preparation method includes: 1. Dispersing trimellitic acid, tantalum pentachloride, and bismuth nitrate pentahydrate in methanol and reacting them solvothermally at 110℃~140℃ to obtain a bismuth-tantalum bimetallic organic framework precursor; 2. Pyrolysis treatment in an H2 / Ar atmosphere at 540~560℃ to obtain a flower-like composite material; 3. Etching the flower-like composite material with HCl solution to obtain the carbon-coated bismuth-tantalum oxide heterojunction catalyst. The carbon-coated bimetallic Bi-Ta organic framework derivative catalyst prepared by this invention exhibits excellent performance in the two-electron oxygen reduction reaction, possessing an ultra-low onset potential and achieving an H2O2 yield of 11.794 mol g. ‑1 h ‑1 The selectivity is close to 100% at 0.5 Acm ‑2 A stability test was conducted for 115 hours under current density conditions, and the performance degradation was negligible.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials technology, specifically relating to a carbon-coated bismuth-tantalum oxide heterostructure catalyst for the preparation of hydrogen peroxide via the two-electron oxygen reduction reaction (2e⁻ORR), its preparation method, and the application of the catalyst in the electrochemical synthesis of hydrogen peroxide. Background Technology

[0002] Energy and environmental issues are core topics for global sustainable development in the 21st century. As one of the most important basic chemicals in the world, hydrogen peroxide (H2O2) has a strategic position in the fields of energy transition and environmental protection due to its unique dual properties—a strong oxidant that is green and environmentally friendly and a carbon-free energy carrier. Specifically, it is manifested in: (1) Environmental governance: It can effectively degrade recalcitrant organic pollutants in wastewater due to its strong oxidizing properties; (2) Industrial application: It is widely used in traditional industries such as paper bleaching, textile dyeing, and food processing. In particular, with the rapid development of the electronic information industry, the demand for electronic-grade high-purity H2O2 has shown exponential growth; (3) New energy development: As a zero-carbon emission energy carrier, it has shown great potential in the fields of fuel cells and clean fuel additives.

[0003] However, current industrial production faces significant technological bottlenecks: the mainstream anthraquinone oxidation method has three major drawbacks: (a) the multi-step reaction process is energy-intensive, generating approximately 2.5 tons of organic waste liquid per ton of H2O2; (b) it relies on a precious metal palladium catalyst (0.3-0.5 wt%); and (c) the concentration process (purifying from 5% to 30-70%) carries an explosion risk. While the alternative direct H2 / O2 synthesis method has a simpler reaction path, it is limited by the explosion limits of the mixed gas (4-94 vol%), requiring the introduction of >50% inert gas for dilution, resulting in a reduction in equipment capacity of over 40%.

[0004] Electrochemical two-electron oxygen reduction (2e - ORR technology has become a breakthrough solution due to its advantages such as operation at room temperature and pressure, immediate use, and no production of toxic byproducts. However, electrochemical two-electron oxygen reduction also faces three major technical problems: (I) 4e - Path competition leads to a decrease in Faraday efficiency (typically <80%); (II) High water dissociation energy barrier (ΔG>1.23eV), resulting in insufficient proton supply; (III) Desorption of intermediates is slow (τ>10ms). Summary of the Invention

[0005] In order to overcome the technical bottlenecks of existing metal-organic framework derivative-based catalysts in terms of product selectivity, catalytic activity and stability, this invention proposes a carbon-coated bismuth-tantalum oxide heterojunction catalyst and its preparation method and application.

[0006] The carbon-coated bismuth-tantalum oxide heterojunction catalyst of this invention is prepared by solvothermal reaction of pyromellitic acid, tantalum pentachloride, and bismuth nitrate pentahydrate to obtain a bismuth-tantalum bimetallic organic framework precursor (BiTa-MOFs). Then, the precursor is obtained by sequential carbonization and acid etching treatments. The chemical formula of the carbon-coated bismuth-tantalum oxide heterojunction catalyst is represented as (Bi / Ta2O). 5-x )@C, where x takes the value 0, 1, 2 or 3.

[0007] In the carbon-coated bismuth-tantalum oxide heterojunction catalyst of this invention, the valence state of Ta is +1, +2, +3, +4, or +5, and the valence state of Bi is greater than or equal to zero and less than +3. In the Bi / Ta₂O₃... 5-x In the oxide, the molar ratio of the corresponding metal Ta to Bi is 1:(1-3).

[0008] The preparation method of the carbon-coated bismuth-tantalum oxide heterojunction catalyst of the present invention is carried out according to the following steps:

[0009] I. Precursor Preparation:

[0010] Tristyric acid, tantalum pentachloride and bismuth nitrate pentahydrate were dispersed in methanol and transferred to a high-pressure reactor with a polytetrafluoroethylene liner. The reaction was carried out at a temperature of 110℃~140℃. After the reaction was completed, the solid phase was collected, washed and dried to obtain the bismuth-tantalum bimetallic organic framework precursor.

[0011] II. Heating and carbonization: The bismuth-tantalum bimetallic organic framework precursor was pyrolyzed at a temperature of 540-560℃ in a (4%~7%) H2 / Ar (V / V) atmosphere to obtain flower-shaped composite material.

[0012] III. The flower-shaped composite material was acid-etched with HCl solution to obtain a carbon-coated bismuth-tantalum oxide heterojunction catalyst (Bi / Ta2O). 5-x )@C.

[0013] The application of the carbon-coated bismuth-tantalum oxide heterojunction catalyst of this invention is as a two-electron oxygen reduction (2e) catalyst. - ORR catalysts have three applications: one is the electrocatalytic preparation of H2O2; the other is the introduction of ethylene into the electrocatalytic H2O2 preparation system for the synthesis of ethylene glycol; and the third is the use of H2O2 prepared by carbon-coated bismuth-tantalum oxide heterojunction catalyst in the Fenton reaction system to degrade industrial dyes in water.

[0014] The carbon-coated bismuth-tantalum oxide heterojunction catalyst of this invention uses metallic Bi and Ta as the core active centers and trimesic acid as the structure inducer. Under a special atmosphere of 5% H2 / Ar (V / V), a composite material with a unique hierarchical structure was successfully constructed through precise control of the pyrolysis process. The 5% H2 / Ar atmosphere plays a dual role: firstly, it controls the oxygen vacancy concentration, optimizing the catalyst's active sites; secondly, during the carbonization process, it promotes the reformation of the originally rod-shaped metal-organic framework precursor into a flower-like catalyst. The chemical formula of this carbon-coated bismuth-tantalum oxide heterojunction catalyst is (Bi / Ta2O). 5-x )@C, where Ta2O 5-x This indicates the presence of oxygen vacancies or defects in Ta2O5.

[0015] The carbon-coated bismuth-tantalum oxide heterojunction catalyst (Bi / Ta2O) prepared by this invention 5-x @C, through interfacial electronic effects: (1) constructing a Bi-Ta dual active center synergistic effect to optimize the adsorption energy of O2; (2) utilizing oxygen vacancies to promote water dissociation; (3) regulating The combination enables rapid desorption. This carbon-coated bismuth-tantalum oxide heterojunction catalyst simultaneously achieves the dual functions of environmental remediation (organic pollutant removal rate >99%) and high-value-added chemical conversion (ethylene glycol selectivity >99.9%), demonstrating significant industrial application value.

[0016] The carbon-coated bimetallic Bi-Ta organic framework derivative catalyst with a heterogeneous structure prepared in this invention is used in the two-electron oxygen reduction reaction (2e... - It exhibits superior performance in ORR, with an ultra-low onset potential (0.637 V vs. RHE) and a H2O2 yield of 11.794 mol g. -1 h -1 (FE=91.69%), at 0.5 A cm -2 Under conditions of 115 h, the degradation is <2%, achieving industrial-grade stability. The resulting H2O2-containing catholyte can efficiently degrade various organic dyes (>99% efficiency) at 0.4-1 A cm⁻¹. -2 Highly selective conversion of ethylene glycol (>99.9%) was achieved at industrial current densities. This not only significantly improved catalytic activity, selectivity, and stability, but also verified its feasibility for industrial applications. Attached Figure Description

[0017] Figure 1 In the example (Bi / Ta2O) 5-x @C catalyst, Bi@C catalyst and Ta2O 5-x Flowchart of the preparation of @C catalyst;

[0018] Figure 2 SEM images of the Bi / Ta-MOFs precursors prepared for the example (Figure a), (Bi / Ta2O) 5-x SEM image (Figure b), secondary electron image (Figure c), and TEM image (Figure de) of the )@C catalyst.

[0019] Figure 3 The (Bi / Ta2O) prepared for the example 5-x )@C, Bi@C and Ta2O 5-x XRD pattern of @C (Figure a), and (Bi / Ta2O) 5-x EPR (Figure b) and BET test results (Figure cd) of the C catalyst;

[0020] Figure 4 The (Bi / Ta2O) prepared for the example 5-x Linear sweep voltammetry of )@C (Figure a), hydrogen peroxide selectivity test graph (Figure b), oxygen reduction reaction onset potential histogram (Figure c), and Tafel curve (Figure d).

[0021] Figure 5 The (Bi / Ta2O) prepared for the example 5-x Yield and Faraday efficiency test graphs for the C catalyst;

[0022] Figure 6 The (Bi / Ta2O) prepared for the example 5-x The yield (green line in Figure a), Faraday efficiency (red line in Figure a), and stability test results of the C catalyst at industrial current density (Figure b).

[0023] Figure 7 The figures shown are the liquid nuclear magnetic resonance hydrogen spectrum (Figure a) of the synthesis of ethylene glycol by electrochemical O2 reduction tandem electrocatalysis and the ultraviolet-visible absorption spectra of the organic dye before and after degradation (Figure bd). Detailed Implementation

[0024] Specific Implementation Method 1: The preparation method of the carbon-coated bismuth-tantalum oxide heterojunction catalyst in this implementation method is carried out according to the following steps:

[0025] I. Precursor Preparation:

[0026] Tristyric acid, tantalum pentachloride and bismuth nitrate pentahydrate were dispersed in methanol and transferred to a high-pressure reactor with a polytetrafluoroethylene liner. The reaction was carried out at a temperature of 110℃~140℃. After the reaction was completed, the solid phase was collected, washed and dried to obtain the bismuth-tantalum bimetallic organic framework precursor.

[0027] II. Heating and carbonization: The bismuth-tantalum bimetallic organic framework precursor was pyrolyzed at a temperature of 540-560℃ in a (4%~7%) H2 / Ar (V / V) atmosphere to obtain flower-shaped composite material.

[0028] III. The flower-shaped composite material was acid-etched with HCl solution to obtain a carbon-coated bismuth-tantalum oxide heterojunction catalyst (Bi / Ta2O). 5-x )@C.

[0029] The carbon-coated bismuth-tantalum oxide heterojunction catalyst prepared in this embodiment uses metallic Bi and Ta as the core active centers and trimesic acid as the structure inducer. Under a special H2 / Ar atmosphere, the pyrolysis process was precisely controlled to successfully construct a composite material with a unique hierarchical structure. This carbon-coated bismuth-tantalum oxide heterojunction catalyst has a BET specific surface area of ​​70-80 m² / g, HRTEM analysis shows a crystal interplanar spacing of 0.15-0.35 nm, and a carbon coating thickness of 2-5 nm.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the molar ratio of tantalum pentachloride and bismuth nitrate pentahydrate in step one is 1:(1-3).

[0031] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the solvothermal reaction is carried out at a temperature of 120°C for 20-26 hours in step 1.

[0032] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that methanol is used for washing in step one, and the drying temperature is 60°C.

[0033] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that the volume fraction of H2 in the H2 / Ar atmosphere in step 2 is 5%.

[0034] This embodiment optimizes the H2 content in the H2 / Ar atmosphere.

[0035] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that, in step two, the bismuth-tantalum bimetallic organic framework precursor is pyrolyzed at a rate of 5℃ / min to 550℃ for 2 to 3 hours.

[0036] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the concentration of the HCl solution in step three is 1 mol / L.

[0037] Specific Implementation Method 8: This implementation method differs from Specific Implementation Method 7 in that the acid etching time for the flower-shaped composite material in step 3 is 4~6 hours.

[0038] Example 1: The preparation method of the carbon-coated bismuth-tantalum oxide heterojunction catalyst in this example is carried out according to the following steps:

[0039] I. Precursor Preparation:

[0040] At room temperature, pyromellitic acid (H3BTC, 375 mg), tantalum pentachloride (TaCl5, 19.7 mg), and bismuth nitrate pentahydrate (Bi(NO3)3·5H2O, 75 mg) were dispersed in methanol (MeOH, 30 mL). After complete dissolution, the solution was transferred to a 50 mL high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 120 °C for 24 h. After the reaction was completed, the solid phase was collected, washed several times with methanol, and dried at 60 °C to obtain a yellow bismuth-tantalum bimetallic organic framework precursor.

[0041] II. Heating and carbonization: The bismuth-tantalum bimetallic organic framework precursor was pyrolyzed for 2 h in a 5% H2 / Ar atmosphere at a temperature of 5℃ / min to 550℃ to obtain a flower-like composite material.

[0042] 3. The flower-like composite material was acid-etched with 1 mol / L HCl solution for 5 h to remove unstable metal particles, improve the stability of the catalyst, and obtain a carbon-coated bismuth-tantalum oxide heterojunction catalyst (Bi / Ta2O). 5-x )@C.

[0043] This embodiment employs a bimetallic (Bi-Ta) heterostructure to construct a synergistic catalytic system. The catalyst has the following characteristics:

[0044] (i) A synergistic catalytic system is constructed using a bimetallic (Bi-Ta) heterostructure, wherein:

[0045] (1) The active center of Bi is regulated by the heterostructure, and the Bi electrons are shifted (+0.11 e), which optimizes its adsorption of O2 and promotes Intermediate formation;

[0046] (2) Oxygen-deficient Ta2O 5-x As a proton source, it promotes the dissociation of water (Ta-H2O bond length: 1.5 Å).

[0047] (3) The carbon coating structure provides a conductive network and stabilizes the metal nanoparticles.

[0048] (4) The BiTa-MOF precursor formed by solvothermal reaction exhibits a cylindrical stacked morphology. After carbonization, the precursor is successfully transformed into a unique flower-like structure composed of nanosheet clusters. These nanosheets are tightly packed in the central region and radiate outward.

[0049] (ii) Performance optimization path:

[0050] ① The oxygen vacancy concentration is controlled by adjusting the carbonization temperature (550℃), heating rate (5℃ / min), and atmosphere type (5%H2 / Ar);

[0051] ② Adjusting the Bi / Ta molar ratio ((0-3):1) regulates electron transfer efficiency;

[0052] ③ Modify the morphology to regulate conductivity and mass transfer efficiency.

[0053] This embodiment overcomes the traditional catalyst activity-stability-selectivity dilemma through a synergistic design of "metal electronic structure regulation - interface proton transport enhancement - three-dimensional conductive network construction". The technical parameters are compared in the table below:

[0054]

[0055] Comparative Example 1: The difference between this example and Example 1 is that in step one, pyromellitic acid (H3BTC, 375 mg) and bismuth nitrate pentahydrate (Bi(NO3)3·5H2O, 75 mg) were dispersed in methanol (MeOH, 30 mL) at room temperature, transferred to a 50 mL high-pressure reactor with a polytetrafluoroethylene liner, and subjected to a solvothermal reaction at 120 °C for 24 h.

[0056] The product prepared in this embodiment is denoted as Bi@C catalyst.

[0057] Comparative Example 2: The difference between this example and Example 1 is that in step 1, pyromellitic acid (H3BTC, 375 mg) and tantalum pentachloride (TaCl5, 19.7 mg) were dispersed in methanol (MeOH, 30 mL) at room temperature, transferred to a 50 mL high-pressure reactor with a polytetrafluoroethylene liner, and subjected to a solvothermal reaction at 120 °C for 24 h.

[0058] The product obtained in this embodiment is denoted as Ta2O. 5-x @C catalyst.

[0059] The morphological and structural characteristics of the carbon-coated bismuth-tantalum oxide heterojunction catalyst prepared in the examples are as follows:

[0060] (1) Appearance

[0061] The catalyst morphology was systematically characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For example... Figure 2 As shown in figure a, the BiTa-MOF precursor prepared by solvothermal reaction exhibits a cylindrical stacked morphology. After carbonization, it is successfully transformed into (Bi / Ta2O) with a unique flower-like structure. 5-xThe structure, represented by @C, consists of clusters of nanosheets, densely packed in the central region and radiating outwards. This indicates that the precursor underwent disintegration and reconstruction during low-temperature carbonization, ultimately forming a layered structure with a larger specific surface area. Figure 2 bc). High-resolution transmission electron microscopy (HRTEM) analysis showed that the 0.24 nm and 0.325 nm lattice fringes corresponded to the crystal planes of Bi and Ta₂O₅, respectively. Notably, the lattice fringes of Ta₂O₅ were blurred, possibly due to oxygen vacancies or defects induced by hydrogen reduction during carbonization. Figure 2 d). The clear interfaces between these crystal planes indicate the interaction between Bi and Ta2O. 5-x Heterojunction was successfully formed. Figure 2 e).

[0062] (2) Structure

[0063] X-ray diffraction (XRD) pattern Figure 3 a) Display, (Bi / Ta2O 5-x The (Bi / Ta2O) composite material exhibits distinct diffraction peaks for metallic Bi and weaker diffraction peaks for Ta2O5. The lower intensity of the Ta2O5 peaks may be due to its small grain size and low content. It is noteworthy that the (Bi / Ta2O) composite material... 5-x The diffraction peaks of )@C systematically shift to higher angles, indicating lattice shrinkage, which may be due to atomic radius mismatch between Bi and Ta or the presence of oxygen vacancies / defects. The characteristic signal at g=2.004 in the electron paramagnetic resonance (EPR) spectrum ( Figure 3 b) Confirmed that (Bi / Ta2O) 5-x The )@C composite material contains paramagnetic oxygen vacancy centers.

[0064] Nitrogen adsorption-desorption analysis revealed (Bi / Ta2O) 5-x The unique texture characteristics of C composite materials Figure 3 The material exhibits a typical Type IV isotherm with a diameter of 75.5 m. 2 g -1 The BET specific surface area and average pore size are 6.86 nm. At relative pressures of 0.4–0.9... The hysteresis loops observed in the intervals confirmed the presence of abundant mesopores (2-50 nm).

[0065] Construction of electrocatalytic system:

[0066] Working electrode: Catalyst slurry (5 mg carbon-coated bismuth-tantalum oxide heterojunction catalyst + 20 µL Nafion + 780 µL ethanol + 200 µL H2O) is coated on the ring disk electrode or the gas diffusion layer.

[0067] Electrolyte: 0.1 M KOH solution (pH=13) or 1 M KOH solution (pH=14)

[0068] Operating parameters: room temperature, oxygen flow rate 30 sccm, applied potential 0-0.7 V vs. RHE or constant current density (0.5 A / cm²). 2 )

[0069] The catalytic test results are as follows:

[0070] Test 1

[0071] 5 μL of catalyst slurry was uniformly coated onto the glassy carbon electrode surface of the annular disk apparatus, serving as the working electrode; Hg / HgO was selected as the reference electrode, and a carbon rod as the counter electrode. Before conducting electrochemical tests, 80 mL of 0.1 mol / L KOH electrolyte was injected into the single-port cell, and O2 gas was continuously introduced for 30 minutes to ensure that the electrolyte reached O2 saturation. During the electrocatalytic O2 reduction process, O2 gas was continuously introduced at a flow rate of 30 mL / min, and the selectivity of the target product was detected by the electrochemical testing system. Specific test results are as follows: Figure 4 As shown.

[0072] Figure 4 ab presented detailed information on Bi@C and Ta2O. 5-x @C and (Bi / Ta2O) 5-x The product distribution and selectivity of three catalysts (Bi / Ta2O) at different voltages (vs. RHE) were studied. Data showed that within the voltage range of 0 to 0.65 V, the product distribution and selectivity of the catalysts were... 5-x The selectivity of Bi@C for H2O2 products consistently remained above 96%; when the voltage was in the range of 0.25-0.45V, its H2O2 selectivity even exceeded 99.9%. In stark contrast, under the same testing conditions, the H2O2 selectivity of Bi@C catalyst was below 82%, and that of Ta2O... 5-x The H2O2 selectivity of the @C catalyst is less than 79%.

[0073] Further analysis revealed that at 1 mA / cm -2 At current densities, (Bi / Ta2O) 5-x The onset potential of the Bi@C catalyst was 0.637 V (vs. RHE), which was significantly positive compared to Bi@C (0.553 V vs. RHE) and Ta2O. 5-x @C (0.544 V vs. RHE) ( Figure 4 c), which fully confirms its role in the two-electron oxygen reduction reaction (2e). - Excellent intrinsic activity in ORR. Furthermore, (Bi / Ta2O) 5-xThe Tafel slope of @C is only 88.8 mV dec -1 It is significantly lower than that of Bi@C (114.12 mV dec). -1 ) and Ta2O 5-x @C(120.04 mV dec -1 A smaller Tafel slope implies that the catalyst has superior reaction kinetics, thus indicating that (Bi / Ta2O) 5-x @C has a stronger ability and efficiency in catalytically generating hydrogen peroxide.

[0074]

[0075] Test 2

[0076] 10 μL of catalyst slurry was uniformly coated onto the surface of the gas diffusion layer to serve as the working electrode; Hg / HgO was selected as the reference electrode, and a carbon rod was used as the counter electrode. Before conducting electrochemical tests, 50 mL of 0.1 mol / L KOH electrolyte was injected into both the cathode and anode chambers, and O2 gas was continuously introduced into the cathode chamber for 30 minutes to ensure that the cathode electrolyte reached O2 saturation.

[0077] Test results are as follows Figure 5 As shown: (Bi / Ta2O) 5-x @C catalyst at 5-70mA cm -2 Within the specified current density range, the H2O2 yield exhibits an approximately linear increasing trend. When the current density reaches a specific value, the H2O2 yield can reach a maximum of [value missing]. It maintains a high Faraday efficiency of 91.69%, demonstrating excellent catalytic performance.

[0078] Test 3

[0079] 20 μL of catalyst slurry was uniformly coated onto the surface of the gas diffusion layer and used as the working electrode. Ag / AgCl was selected as the reference electrode, and IrO2 / Ti as the counter electrode. A 1 mol / L KOH solution was used as the electrolyte. During the catalytic reaction, O2 gas was continuously introduced into the cathode chamber to ensure that the cathode electrolyte was always saturated with O2.

[0080] For (Bi / Ta2O) 5-x The yield, Faraday efficiency, and stability of the C catalyst were systematically tested. The test results are as follows: Figure 6 As shown: at industrial-grade current densities (0.4-1 A cm⁻¹) -2 Within the specified range, this catalyst system exhibits excellent performance, maintaining a stable 7-15 mmol / h. -1 cm -2The yield of H2O2 is high, while maintaining a high Faraday efficiency of 70-95%. Particularly noteworthy is the high Faraday efficiency at 0.5A cm⁻¹. -2 After running continuously for 115 hours at a current density, the catalyst performance showed almost no significant degradation, demonstrating extremely strong stability and durability.

[0081] Test 4

[0082] In utilizing (Bi / Ta2O) 5-x When the C-catalyst undergoes an electrochemical oxygen reduction reaction, the main product is hydrogen peroxide. Under industrial application conditions, this catalyst exhibits dual functional characteristics, making it suitable for both environmental remediation and high-value-added chemical conversion.

[0083] This study achieved an integrated cascade reaction of hydrogen peroxide to ethylene glycol using a series flow cell system: In the first stage, carbon dioxide was electrochemically reduced using a copper-based catalyst to produce ethylene gas; simultaneously, in a separate reactor, (Bi / Ta2O) was used... 5-x The catalyst (@C) converts O2 into H2O2 solution. In the subsequent oxidation coupling process, a 50 mL 0.1 M H2SO4 electrolyte system containing 2 g TS-1 zeolite catalyst was saturated with in-situ generated ethylene gas. Through H2O2-mediated selective oxidation, only ethylene glycol was detected as the final product. This result demonstrates that tandemly linking the electrochemical reduction of O2 with the ethylene oxidation process can produce ethylene glycol with high selectivity, thereby obtaining a high-value-added product (see [link to relevant documentation]). Figure 7 a).

[0084] Furthermore, when (Bi / Ta2O) 5-x When the @C catalyst is integrated into the Fenton system, only 3 mL of acidified cathode electrolyte is needed to completely decompose three typical industrial dyes (MB, RB, and AO7, all at a concentration of 25 ppm) within 5 minutes, with a degradation efficiency exceeding 99%, demonstrating a highly efficient degradation capability for organic pollutants (see [link to Fenton system]). Figure 7 (bd). It should be emphasized that the above tests are all practical application examples of this catalyst.

[0085] This invention not only discloses a method for preparing a carbon-coated bismuth-tantalum oxide heterostructure catalyst, but also further reveals the specific application scenarios of this catalyst. The catalyst prepared by this method is mainly suitable for electrochemical oxygen reduction to produce hydrogen peroxide, ethylene gas tandem reaction conversion, and organic dye decomposition. The relevant reaction conditions have been described in detail above and will not be repeated here.

[0086] This preparation method has significant advantages: the technical route is simple and easy to understand, and the operation process is convenient and easy to implement. The precursor is obtained by solvothermal precipitation reaction of bismuth salt, tantalum salt, and the structure-directing agent trimesoate, followed by high-temperature carbonization of the precursor to achieve mass synthesis of the catalyst. When using this catalyst for catalytic reactions, the reaction conditions are mild, and hydrogen peroxide can be generated with high selectivity at relatively low voltage.

[0087] From a performance perspective, the carbon-coated bismuth-tantalum oxide heterostructure catalyst prepared by this method exhibits superior characteristics. Firstly, it demonstrates exceptional stability and excellent mechanical strength, maintaining stable catalytic performance even during prolonged electrochemical oxygen reduction reactions, effectively preventing catalyst loss and thus improving product quality and reducing production costs. Secondly, this catalyst offers advantages such as low cost and environmental friendliness, and exhibits extremely high selectivity for hydrogen peroxide products. In the electrocatalytic oxygen reduction reaction, the Faradaic efficiency of hydrogen peroxide products generated using this catalyst reaches over 90%, significantly reducing the formation of water as a byproduct and greatly improving energy utilization efficiency.

[0088] In summary, the carbon-coated bismuth-tantalum oxide heterostructure catalyst prepared by this invention successfully overcomes the problems of poor stability, low hydrogen peroxide yield, high energy consumption, and environmental impact associated with traditional catalysts.

[0089] Obviously, the above description is only a portion of the preferred embodiments and core technical principles employed in this invention. Those skilled in the art should understand that this invention is not limited to the specific embodiments described above. Without departing from the core technical concept of this invention, those skilled in the art can make various modifications, adjustments, and substitutions, and all such changes should be included within the scope of protection of this invention. Therefore, although the invention has been described in detail through the above embodiments, the scope of protection of this invention is not limited thereto. Based on the innovative concept of this invention, more equivalent embodiments can be derived, and the actual scope of protection of this invention will be determined by the appended claims.

Claims

1. A method for preparing a carbon-coated bismuth-tantalum oxide heterojunction catalyst, characterized in that... The preparation method is carried out according to the following steps: I. Precursor Preparation: Tristyric acid, tantalum pentachloride and bismuth nitrate pentahydrate were dispersed in methanol and transferred to a high-pressure reactor with a polytetrafluoroethylene liner. The reaction was carried out at a temperature of 110℃~140℃. After the reaction was completed, the solid phase was collected, washed and dried to obtain the bismuth-tantalum bimetallic organic framework precursor. II. Heating and carbonization: The bismuth-tantalum bimetallic organic framework precursor was pyrolyzed at 540-560℃ in a 4%~7%H2 / Ar atmosphere to obtain flower-like composite material. III. The flower-shaped composite material was acid-etched with HCl solution to obtain a carbon-coated bismuth-tantalum oxide heterojunction catalyst (Bi / Ta2O). 5-x )@C, where x takes the value 0, 1, 2 or 3; The carbon-coated bismuth-tantalum oxide heterojunction catalyst (Bi / Ta2O) 5-x In C, the valence state of Ta is +2, +3, +4, or +5, and the valence state of Bi is greater than or equal to zero and less than +3.

2. The preparation method of the carbon-coated bismuth-tantalum oxide heterojunction catalyst according to claim 1, characterized in that... In step one, the molar ratio of tantalum pentachloride and bismuth nitrate pentahydrate is 1:(1-3).

3. The method for preparing the carbon-coated bismuth-tantalum oxide heterojunction catalyst according to claim 1, characterized in that... In step one, a solvothermal reaction is carried out at a temperature of 120℃ for 20~26h.

4. The method for preparing the carbon-coated bismuth-tantalum oxide heterojunction catalyst according to claim 1, characterized in that... In step one, methanol is used for washing, and the drying temperature is 60°C.

5. The method for preparing the carbon-coated bismuth-tantalum oxide heterojunction catalyst according to claim 1, characterized in that... In step two, the volume fraction of H2 in the H2 / Ar atmosphere is 5%.

6. The method for preparing the carbon-coated bismuth-tantalum oxide heterojunction catalyst according to claim 1, characterized in that... In step two, the bismuth-tantalum bimetallic organic framework precursor is pyrolyzed at a rate of 5℃ / min to 550℃ for 2-3 hours.

7. The method for preparing the carbon-coated bismuth-tantalum oxide heterojunction catalyst according to claim 1, characterized in that... In step three, the concentration of the HCl solution is 1 mol / L.

8. The method for preparing the carbon-coated bismuth-tantalum oxide heterojunction catalyst according to claim 7, characterized in that... In step three, the acid etching treatment time for the flower-shaped composite material is 4-6 hours.

9. The application of the carbon-coated bismuth-tantalum oxide heterojunction catalyst obtained by the preparation method according to claim 1, characterized in that... The carbon-coated bismuth-tantalum oxide heterojunction catalyst was used as a two-electron oxygen reduction catalyst for the electrocatalytic preparation of H2O2. In another application, ethylene was introduced into the H2O2 electrocatalytic preparation system for the synthesis of ethylene glycol. Finally, the H2O2 prepared by the carbon-coated bismuth-tantalum oxide heterojunction catalyst was used in a Fenton reaction system to degrade industrial dyes in water.

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