Metal oxide and carbon material composite catalyst as well as preparation method and application thereof

Abstract

The invention discloses a metal oxide-carbon material composite catalyst as well as a preparation method and application thereof. The metal oxide-carbon material composite catalyst comprises a metal oxide phase, a carbon material phase and electron bridging atoms, the metal oxide and carbon material composite catalyst is represented by the following general formula: A-X-B, where A represents a metal oxide phase, B represents a carbon material phase, and X represents an electron bridging atom; the metal oxide phase and the carbon material phase are connected through electron bridging atoms to form an electron bridging structure; the electron bridging structure is represented by the following general formula: M-X-C, M represents a metal atom in a metal oxide phase, C represents a carbon atom in a carbon material phase, and X represents an electron bridging atom; m comprises at least one of Fe, Co and Mn. A stable electron bridging structure is formed in the catalyst, efficient synergistic catalysis between oxidant molecules and pollutant molecules can be achieved, and the catalyst has good catalysis and stability performance.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly to a metal oxide@carbon material composite catalyst, a preparation method thereof, and uses thereof. Background Art

[0002] For a long time, advanced oxidation processes (AOPs) have been widely used due to their high efficiency in removing refractory organic pollutants. They mainly rely on catalysts to activate oxidants (such as persulfate, hydrogen peroxide) to generate reactive oxygen species (ROS), and then achieve the mineralization and degradation of pollutants through free radical chain reactions. However, such catalysts have obvious limitations: the catalytic activity highly depends on the ROS generated by the activation of oxidants at single sites, and the strong oxidizing property of ROS easily leads to surface passivation or structural damage of the catalyst, resulting in a decrease in the catalytic effect and service life of the catalyst.

[0003] Therefore, it is necessary to develop a highly active and highly stable catalyst that can achieve synergistic catalysis between the oxidant and pollutant at two sites in view of the above defects. Summary of the Invention

[0004] The present invention provides a metal oxide@carbon material composite catalyst, a preparation method thereof, and uses thereof. The composite catalyst forms a stable electron bridging structure by connecting the metal oxide phase and the carbon material phase through electron bridging atoms, and can achieve efficient synergistic catalysis between oxidant molecules and pollutant molecules, and has high catalytic performance and stability.

[0005] According to one aspect of the present invention, there is provided a metal oxide@carbon material composite catalyst, which is characterized by comprising a metal oxide phase, a carbon material phase, and electron bridging atoms; the metal oxide@carbon material composite catalyst is represented by the following general formula: A-X-B, where A represents the metal oxide phase, B represents the carbon material phase, and X represents the electron bridging atoms; the metal oxide phase and the carbon material phase are connected through the electron bridging atoms to form an electron bridging structure; the electron bridging structure is represented by the following general formula: M-X-C, where M represents the metal atom in the metal oxide phase, C represents the carbon atom in the carbon material phase, and X represents the electron bridging atoms; M includes at least one of Fe, Co, and Mn.

[0006] The metal oxide@carbon material composite catalyst of the present invention forms a dual-active site structure based on the electron-bridging atoms between the metal oxide phase and the carbon material phase. Among them, the metal oxide phase can adsorb and activate oxidant molecules, and the carbon material phase can adsorb and activate organic pollutant molecules; the two-phase interface forms a stable electron-bridging structure with electron transfer through the electron-bridging atoms, promoting the directional electron migration and energy coupling between the activated oxidant molecules and the pollutant molecules at the dual-active site interface, and realizing the efficient synergistic catalysis between the oxidant molecules and the pollutant molecules. In addition, the composite catalyst uses the stabilization effect of the interfacial chemical bonds in the electron-bridging atoms to inhibit the dissolution of the active components in the catalyst and the poisoning effect of intermediate products, thereby realizing the efficient degradation of organic pollutants in industrial wastewater under complex water quality conditions and the long-term cyclic stability of the catalytic system. Therefore, the composite catalyst has high catalytic performance and stability.

[0007] Preferably, X includes at least one of N, O, and B. The metal oxide@carbon material composite catalyst of the present invention uses nitrogen, oxygen, or boron as the bridging atoms to achieve the interfacial bonding between the metal oxide phase and the carbon material phase.

[0008] Preferably, the metal oxide phase includes at least one of Fe2O3, Co3O4, NiO, ZnO, and Mn3O4.

[0009] Preferably, the carbon material phase includes at least one of carbon black (CB), biochar, carbon nanotubes (CNT), and reduced graphene oxide (rGO).

[0010] Preferably, calculated by mass percentage, the metal loading in the metal oxide@carbon material composite catalyst is 0.5~20 wt%.

[0011] According to another aspect of the present invention, there is provided a method for preparing a metal oxide@carbon material composite catalyst, comprising the following steps: Prepare a precursor containing a metal compound and a carbon material, and then calcine the precursor at 300~500 o °C for 1~3 h to obtain the metal oxide@carbon material composite catalyst. The method for preparing the metal oxide@carbon material composite catalyst in the present invention has the characteristics of simple process, easy operation, and environmental harmlessness, and can meet the requirements of practical applications in environmental catalysis. By regulating the calcination temperature, this preparation method optimizes the dispersion degree of the metal active sites and the stability of the carbon skeleton structure of the composite catalyst, realizes the construction of the electron-bridging atoms between the metal oxide phase and the carbon material phase, and forms a stable dual-active site structure.

[0012] Preferably, the metal compound includes at least one of FeCl3, CoCl2, ZnCl2, MnCl2, Fe2(SO4)3, CoSO4, ZnSO4, MnSO4, Fe(NO3)3, Co(NO3)2, Zn(NO3)2, Mn(NO3)2, Fe2O3, Co3O4, NiO, ZnO, Mn3O4.

[0013] Preferably, the carbon material includes at least one of carbon black (CB), biochar, carbon nanotubes (CNT), and reduced graphene oxide (rGO).

[0014] Preferably, the heating rate during calcination is 1 - 10 o °C / min.

[0015] Preferably, calculated by mass ratio, metal compound : carbon material = (0.5 - 1.5) : (1 - 3).

[0016] Preferably, the precursor is prepared by the impregnation method, including the following steps: uniformly dispersing the metal compound and the carbon material into ethanol to obtain mixture A, then dropping an electron - bridging atom introducing agent into mixture A, and drying the above - mentioned mixture under the condition of 50 - 70 o °C to obtain the precursor. When X includes N, the electron - bridging atom introducing agent includes ammonia water; when X includes O, the electron - bridging atom introducing agent includes sulfuric acid; when X includes B, the electron - bridging atom introducing agent includes boric acid.

[0017] Preferably, calculated by mass ratio, metal compound : carbon material : ammonia water = (0.5 - 1.5) : (1 - 3) : (0.5 - 1.5).

[0018] Preferably, calculated by molar concentration, the concentration of ammonia water is 0.1 - 1 mol / L.

[0019] Preferably, the precursor is prepared by the mixing method, including the following steps: uniformly dispersing the metal compound, the carbon material, and the ammonium salt into ethanol to obtain mixture B, and drying mixture B under the condition of 80 - 100 o °C to obtain the precursor. The above - mentioned mixing method has the characteristics of simple process and convenient operation. Only by simply mixing and calcining the materials, the preparation of large - scale high - performance catalysts can be realized.

[0020] Preferably, calculated by mass ratio, metal compound : carbon material : ammonium salt = (0.5 - 1.5) : (1 - 3) : (0.5 - 1.5).

[0021] Preferably, the ammonium salt is ammonium chloride.

[0022] According to another aspect of the present invention, there is provided a use of a metal oxide@carbon material composite catalyst in treating industrial wastewater. When the above-mentioned metal oxide@carbon material composite catalyst is applied to the treatment of industrial wastewater, it can not only improve the treatment efficiency of industrial wastewater, but also improve the stability of the treatment work of industrial wastewater.

[0023] Preferably, the pollutants in the industrial wastewater include at least one of phenol, aniline, and bisphenol A.

[0024] Preferably, the oxidants used in the oxidative coupling polymerization reaction include at least one of hydrogen peroxide, persulfate, and peracetic acid. Detailed implementation manners

[0025] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0026] Example 1 This example provides an Fe2O3@rGO composite catalyst, and the specific preparation steps are as follows: (1) Uniformly disperse the carbon material and the metal compound in ethanol to obtain a mixture A, and then dropwise add ammonia water to the mixture A and dry it under the condition of 60 o °C to obtain a precursor; wherein, the carbon material is rGO and the metal compound is Fe2O3; calculated by mass ratio, Fe2O3:rGO:ammonia water = 1:2:1; calculated by molar concentration, the concentration of ammonia water is 1 mol / L; (2) Lay the precursor obtained in (1) flat in a magnetic boat, and then place the magnetic boat in a muffle furnace. Heat the above-mentioned precursor to 400 o °C at a heating rate of 5 o °C / min, and calcine for 2 hours at this temperature condition, and then cool the calcined product to room temperature to obtain an Fe2O3@rGO composite catalyst. The electron bridging atom in the above Fe2O3@rGO composite catalyst is N, and the formed electron bridging structure is Fe-N-C.

[0027] Example 2 This example provides a Co3O4@CNT composite catalyst. Compared with Example 1, the difference in composition is that this example uses an equal amount of Co3O4 to replace Fe2O3 and an equal mass of CNT to replace rGO. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron bridging atom in the above Co3O4@CNT composite catalyst is N, and the formed electron bridging structure is Co-N-C.

[0028] Example 3 This example provides a Mn3O4@CNT composite catalyst. Compared with Example 1, the compositional difference is that in this example, equimolar amounts of Mn3O4 are used to replace Fe2O3, and CNT of equal mass is used to replace rGO. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron-bridging atom in the above Mn3O4@CNT composite catalyst is N, and the formed electron-bridging structure is Mn-N-C.

[0029] Example 4 This example provides a ZnO@CNT composite catalyst. Compared with Example 1, the compositional difference is that in this example, equimolar amounts of ZnO are used to replace Fe2O3, and CNT of equal mass is used to replace rGO. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron-bridging atom in the above ZnO@CNT composite catalyst is N, and the formed electron-bridging structure is Zn-N-C.

[0030] Example 5 This example provides an Fe2O3@rGO composite catalyst. Compared with Example 1, the compositional difference is that in the preparation process of the precursor in (1) of this example, the metal compound, carbon material, and ammonium salt are uniformly dispersed in ethanol to obtain mixture B, and mixture B is dried under the condition of 90 o °C to obtain the precursor; among them, the carbon material is rGO, the metal compound is Fe2O3, and the ammonium salt is ammonium chloride; calculated by mass ratio, Fe2O3:rGO:ammonium chloride = 1:2:1. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron-bridging atom in the above Fe2O3@rGO composite catalyst is N, and the formed electron-bridging structure is Fe-N-C.

[0031] Comparative Example 1 This comparative example provides an Fe2O3 composite catalyst. Compared with Example 1, the compositional difference is that in (1) of this comparative example, the raw materials for preparing mixture A do not include carbon materials, and equimolar amounts of metal compounds are used to replace carbon materials. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1.

[0032] Comparative Example 2 This comparative example provides an rGO composite catalyst. Compared with Example 1, the difference in composition is that in this comparative example, the raw materials for preparing mixture A in (1) do not include metal compounds, and an equal amount of carbon material is used to replace the metal compounds. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1.

[0033] Comparative Example 3 This comparative example provides an Fe2O3@rGO composite catalyst. Compared with Example 1, the difference in composition is that in the process of preparing the Fe2O3@rGO composite catalyst in this comparative example, step (2) is directly omitted. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1.

[0034] Comparative Example 4 This comparative example provides an Fe2O3@rGO composite catalyst. Compared with Example 5, the difference in composition is that in the process of preparing the Fe2O3@rGO composite catalyst in this comparative example, step (2) is directly omitted. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 5.

[0035] Test Example 1 1. Test object: The composite catalysts provided in Examples 1 - 5 and Comparative Examples 1 - 4 are used as test objects in this test example for relevant performance tests.

[0036] 2. Test content: Phenol degradation rate: The catalytic activity of the test object was evaluated by the degradation rate in the phenol (PhOH) degradation reaction. The specific degradation experiment steps are as follows: 4 mg of the test object and 20 mL of 12.5 mg / L PhOH deionized aqueous solution were mixed in a beaker, dissolved under ultrasonic conditions. After complete dissolution, a magnetic stir bar was added, and the mixture was placed on a magnetic stirrer and stirred at a speed of 300 r / min for 5 h for pre-adsorption to obtain a pre-adsorbed solution. After the pre-adsorption was completed, 1 mL of the pre-adsorbed solution was added to a 2 mL centrifuge tube containing 100 μL of 0.1 M ascorbic acid solution, and then persulfate solution (PMS) was added to make the PMS concentration in the reaction system 0.266 mM. At the 30th minute after adding PMS, 1 mL of the reaction sample was taken and placed in a 2 mL centrifuge tube containing 100 μL of 0.1 M ascorbic acid solution for storage. After the reaction sample was filtered through a 0.22 μm filter membrane, the remaining PhOH concentration in the reaction sample (C1) was measured. The PhOH concentration was determined by UPLC. The UPLC test conditions are as follows: the chromatographic column is a C18 reverse-phase chromatographic column, the solvent is acetonitrile: water (containing 1‰ formic acid) = 20:80 (v / v), the flow rate is 0.3 mL / min, the detection wavelength is 270 nm, the injection volume is 2 μL, and the running time is 3 min. The calculation formula for the phenol degradation rate is as follows: Phenol degradation rate (%) =

[0037] 3. Test results: Table 1 Test results of the relevant properties of the composite catalyst

[0038] The catalytic performance of the metal oxide@carbon material composite catalysts provided in Examples 1 to 5 of the present invention is significantly better than that of Comparative Examples 1 to 4. Specifically, the metal oxide@carbon material composite catalysts provided by the present invention form a stable electron bridging structure by connecting the metal oxide phase and the carbon material phase through electron-bridging atoms, realizing efficient cooperative catalysis between oxidant molecules and pollutant molecules.

[0039] Among them, the metal oxide@carbon material composite catalysts provided in Examples 1 to 4 of the present invention exhibit excellent catalytic activity through the Fe-N-C, Co-N-C, Mn-N-C, and Zn-N-C structures formed by electron-bridging atoms (N) respectively. The phenol degradation rate exceeds 90% within 30 minutes, and the order of the phenol degradation rate reaching 100% in the degradation reaction is: Example 2, Example 1, Example 3, Example 4, indicating that the preferred order of the electron-bridging structure is Co-N-C, Fe-N-C, Mn-N-C, Zn-N-C. In Example 1, the precursor was prepared by the impregnation method, and in Example 5, the precursor was prepared by the mixing method. The phenol degradation rate of the composite catalyst prepared in Example 1 reached 100% faster than that in Example 5, indicating that the catalytic performance of the composite catalyst prepared by the impregnation method to prepare the precursor is better than that of the mixing method.

[0040] The composite catalysts provided in Comparative Example 1 each include a metal oxide phase, and the composite catalysts provided in Comparative Examples 3 and 4 include a metal oxide phase and a carbon material phase. As can be seen from Table 1, the catalytic performance of the composite catalyst provided in Comparative Example 1 is worse than that of Comparative Examples 3 and 4, indicating that when the metal oxide phase and the carbon material phase coexist, they can play a synergistic catalytic effect on phenol degradation through adsorption. However, the catalytic performance of Comparative Examples 3 and 4 is still significantly worse than that of Examples 1 to 4. The reason is that Comparative Examples 3 and 4 only prepared the composite catalyst by direct physical mixing of the materials and did not form a chemically bonded electron-bridging structure through high-temperature calcination. This shows the important role of the electron-bridging structure in achieving the technical effects of the present invention.

[0041] Example 6 This example provides an Fe2O3@CB composite catalyst. Compared with Example 1, the difference in composition is that in this example, an equal mass of CB is used to replace rGO. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron-bridging atom in the above Fe2O3@CB composite catalyst is N, and the formed electron-bridging structure is Fe-N-C.

[0042] Example 7 This example provides an Fe2O3@Biochar composite catalyst. Compared with Example 1, the difference in composition is that in this example, an equal mass of Biochar is used to replace rGO. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron-bridging atom in the above Fe2O3@Biochar composite catalyst is N, and the formed electron-bridging structure is Fe-N-C.

[0043] Example 8 This example provides an Fe2O3@CNT composite catalyst. Compared with Example 1, the difference in composition is that this example uses an equal mass of CNT to replace rGO. Except for the above differences, the materials, formulation ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron-bridging atom in the above Fe2O3@CNT composite catalyst is N, and the formed electron-bridging structure is Fe-N-C.

[0044] Comparative Example 5 This comparative example provides an Fe2O3@CB composite catalyst. Compared with Example 5, the difference in composition is that in the process of preparing the Fe2O3@CB composite catalyst in this comparative example, step (2) is directly omitted. Except for the above differences, the materials, formulation ratios, and preparation operations used in this comparative example are strictly the same as those in Example 5.

[0045] Comparative Example 6 This comparative example provides an Fe2O3@Biochar composite catalyst. Compared with Example 6, the difference in composition is that in the process of preparing the Fe2O3@Biochar composite catalyst in this comparative example, step (2) is directly omitted. Except for the above differences, the materials, formulation ratios, and preparation operations used in this comparative example are strictly the same as those in Example 6.

[0046] Comparative Example 7 This comparative example provides an Fe2O3@CNT composite catalyst. Compared with Example 7, the difference in composition is that in the process of preparing the Fe2O3@CNT composite catalyst in this comparative example, step (2) is directly omitted. Except for the above differences, the materials, formulation ratios, and preparation operations used in this comparative example are strictly the same as those in Example 7.

[0047] Test Example 2 1. Test object: In this test example, the composite catalysts provided in Examples 6 - 8 and Comparative Examples 5 - 7 are used as test objects for relevant performance tests.

[0048] 2. Test content: Phenol degradation rate: The same as Test Example 1.

[0049] 3. Test results: Table 2. Test results of relevant performance of the composite catalyst

[0050] In Examples 6 - 8, the type of carbon material was replaced compared with Example 1. As can be seen from Table 2, the phenol degradation rates of the composite catalysts provided in Examples 1, 6, and 8 all reached 100% within 30 minutes, indicating that the composite catalysts prepared using rGO, CNT, and CB as carbon materials have better effects than Biochar. Further, the order of the phenol degradation rate reaching 100% in the degradation reaction for the composite catalysts provided in Examples 1, 6, and 8 is: Example 1, Example 8, Example 6. Combining with the order of the degradation rate, the preferred order of the carbon materials is: rGO, CNT, CB, Biochar.

[0051] There are also differences in the catalytic performance among the composite catalysts provided in Comparative Examples 1, 5 - 7. The reason lies in the different carbon material raw materials. Different carbon materials affect the catalytic activity through the differences in adsorption capacity and surface properties, further indicating that the type of carbon material has an impact on the catalytic performance of the composite catalyst.

[0052] Example 9 This example provides an Fe2O3@rGO composite catalyst. Compared with Example 1, the difference in composition is that the calcination temperature of the precursor in (2) of this example is 280 o °C. Except for the above - mentioned difference, the materials, formula ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron - bridging atom in the above - mentioned Fe2O3@rGO composite catalyst is N, and the formed electron - bridging structure is Fe - N - C.

[0053] Example 10 This example provides an Fe2O3@rGO composite catalyst. Compared with Example 1, the difference in composition is that the calcination temperature of the precursor in (2) of this example is 300 o °C. Except for the above - mentioned difference, the materials, formula ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron - bridging atom in the above - mentioned Fe2O3@rGO composite catalyst is N, and the formed electron - bridging structure is Fe - N - C.

[0054] Example 11 This example provides an Fe2O3@rGO composite catalyst. Compared with Example 1, the difference in composition is that the calcination temperature of the precursor in (2) of this example is 500 o °C. Except for the above - mentioned difference, the materials, formula ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron - bridging atom in the above - mentioned Fe2O3@rGO composite catalyst is N, and the formed electron - bridging structure is Fe - N - C.

[0055] Test Example 3 1. Test object: In this test example, the composite catalysts provided in Examples 9 - 11 are used as the test objects for relevant performance tests.

[0056] 2. Test content: Phenol degradation rate: The same as in Test Example 1.

[0057] 3. Test results: Table 3 Test results of relevant performance of the composite catalyst

[0058] In Examples 9 - 11, the calcination temperature during the calcination process was replaced compared with Example 1. The results show that the performance of the composite catalyst prepared at a calcination temperature of 400°C - 500°C is better than that at a calcination temperature of 280°C - 400°C, indicating that by regulating the calcination temperature, the dispersion of the metal active sites and the stability of the carbon skeleton structure of the composite catalyst can be optimized, realizing the construction of electron - bridging atoms between the metal oxide phase and the carbon material phase, and forming a stable dual - active - site structure.

[0059] Example 12 This example provides an Fe2O3@rGO composite catalyst. Compared with Example 1, the difference in composition is that this example uses an equal amount of sulfuric acid to replace ammonia water. Except for the above - mentioned difference, the materials, formula ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron - bridging atom in the above - mentioned Fe2O3@rGO composite catalyst is O, and the formed electron - bridging structure is Fe - O - C.

[0060] Example 13 This example provides an Fe2O3@rGO composite catalyst. Compared with Example 1, the difference in composition is that this example uses an equal amount of sodium borate to replace ammonia water. Except for the above - mentioned difference, the materials, formula ratios, and preparation operations used in this example are strictly the same as those in Example 1. The electron - bridging atom in the above - mentioned Fe2O3@rGO composite catalyst is B, and the formed electron - bridging structure is Fe - B - C.

[0061] Test Example 4 1. Test object: In this test example, the composite catalysts provided in Examples 12 - 13 are used as the test objects for relevant performance tests.

[0062] 2. Test content: Phenol degradation rate: The same as in Test Example 1.

[0063] 3. Test results: Table 4 Test results of relevant performance of the composite catalyst

[0064] In Examples 12 to 13, the materials for introducing the electron-bridging atoms were replaced compared with Example 1. As can be seen from Table 4, the degradation rates of phenol provided by Examples 12 to 13 reached 100% within 30 minutes, indicating that in addition to N, O and B can also be used as electron-bridging atoms to connect the metal oxide phase and the carbon material phase, realizing the interfacial bonding between the metal oxide phase and the carbon material phase. Further, the order of the degradation rates of phenol reaching 100% for the composite catalysts provided by Examples 1, 12 to 13 in the degradation reaction is: Example 1, Example 12, Example 13. Combining with the order of the degradation rates, the preferred order of the electron-bridging atoms is: N, O, B.

[0065] The above examples are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the above examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced, but these modifications or replacements are all within the protection scope of the present invention.

Claims

1. A metal oxide@carbon material composite catalyst, characterized in that: Includes metal oxide phase, carbon material phase, and electron-bridging atoms; The metal oxide@carbon material composite catalyst is represented by the following general formula: AXB, wherein A represents a metal oxide phase, B represents a carbon material phase, and X represents an electron bridging atom; the metal oxide phase and the carbon material phase are connected by the electron bridging atom to form an electron bridging structure; The electron bridging structure is represented by the following general formula: MXC, wherein M represents the metal atom in the metal oxide phase, C represents the carbon atom in the carbon material phase, and X represents the electron bridging atom; and M includes at least one of Fe, Co, and Mn.

2. The metal oxide@carbon material composite catalyst according to claim 1, characterized in that: The X includes at least one of N, O and B.

3. The metal oxide@carbon material composite catalyst according to claim 1, characterized in that: The metal oxide phase includes at least one of Fe2O3, Co3O4, NiO, ZnO, and Mn3O4.

4. The metal oxide@carbon material composite catalyst according to claim 1, characterized in that: The carbon material phase includes at least one of carbon black, biochar, carbon nanotubes, and graphene.

5. The metal oxide@carbon material composite catalyst according to claim 1, characterized in that: Calculated by mass percentage, the metal loading in the metal oxide@carbon material composite catalyst is 0.5-20 wt%.

6. A method for preparing the metal oxide@carbon material composite catalyst according to any one of claims 1 to 5, characterized in that: The following steps are involved: Prepare a precursor containing a metal compound and a carbon material, then heat the precursor at 300-500 o C for 1 to 3 hours to obtain the metal oxide@carbon material composite catalyst.

7. The preparation method according to claim 6, characterized in that: Calculated by mass ratio, the metal compound: the carbon material = (0.5~1.5): (1~3).

8. The preparation method according to claim 6, characterized in that: The precursor is prepared by an impregnation method, comprising the following steps: uniformly dispersing a metal compound and a carbon material in ethanol to obtain a mixture A, then dropping an electron bridging atom introducing agent into the mixture A, and heating the obtained mixture at 50-70°C. o C to obtain the precursor; When the X includes N, the electron bridging atom introducing agent includes ammonia water; When the X includes O, the electron bridging atom introducing agent includes sulfuric acid; When the X includes B, the electron-bridging atom introducing agent includes boric acid.

9. The preparation method according to claim 6, characterized in that: The precursor is prepared by a mixing method, comprising the following steps: uniformly dispersing a metal compound, a carbon material, and an ammonium salt in ethanol to obtain a mixture B; o C to obtain the precursor.

10. Use of the metal oxide@carbon material composite catalyst according to any one of claims 1 to 5 in treating industrial wastewater.

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