Transition metal-based heterojunction catalyst based on oxygen vacancy bridging, preparation method and application thereof in water treatment

Abstract

The present application relates to the field of catalyst technology, in particular to a transition metal-based heterojunction catalyst based on oxygen vacancy bridging, a preparation method and application thereof in water treatment. The transition metal-based heterojunction catalyst comprises a metal oxide and a corresponding zero-valent metal or a corresponding mixed-state metal oxide stacked in sequence, and forms a heterojunction with an interface rich in oxygen vacancies. A built-in electric field is spontaneously formed at the interface of the heterojunction based on the Fermi level difference, and a non-symmetric structure of electron-deficient sites and electron-rich sites is formed at the interface. Oxygen vacancies form a continuous electron transfer channel between the electron-deficient sites and the electron-rich sites as an electron bridge, realizing the cyclic transfer of electrons between the electron-deficient sites and the electron-rich sites, so that the interface of the heterojunction can simultaneously activate the oxidizing agent based on the free radical path and the non-free radical electron transfer path, improving the activation performance of the transition metal-based heterojunction catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a transition metal-based heterojunction catalyst based on oxygen vacancy bridging, its preparation method, and its application in water treatment. Background Technology

[0002] Advanced oxidation technologies play an irreplaceable role in the treatment of recalcitrant organic pollutants due to their ability to generate highly reactive oxidizing species. Among these, ozone oxidation and Fenton-like technologies (such as systems based on peracetic acid (PPA) or persulfate (PMS)) are two mainstream technologies, each with its own characteristics. Ozone catalytic oxidation technology uses molecular ozone (O3) and derived free radicals (such as •OH) as the main oxidants, featuring rapid reaction rates, strong oxidation capacity, and no secondary residues. This technology is widely used in drinking water disinfection, decolorization and deodorization, industrial wastewater pretreatment, and the breaking down of chain reactions in some poorly biodegradable wastewater. The process is mature and has significant advantages in improving water quality sensory indicators and inactivating pathogenic microorganisms. Fenton-like technologies, on the other hand, demonstrate great potential for the deep oxidation and removal of emerging organic pollutants in water (such as antibiotics and endocrine disruptors) due to their mild operating conditions, diverse oxidants (such as PMS and PAA), and highly designable catalysts. In particular, Fenton-like systems based on persulfate (PMS / PDS) and peracetic acid (PAA) can generate more potent sulfate radicals (SO4) through activation. •- The activation of hydroxyl radicals (•OH) has become a research hotspot in recent years. Among Fenton-like oxidants, peracetic acid (PAA) and persulfate (PMS) have attracted much attention due to their environmental friendliness and diverse activation pathways.

[0003] To date, two main reaction pathways in ozone catalytic oxidation and Fenton-like systems have been widely recognized: free radicals (such as •OH, RO•, SO42-) •- ) and non-radical pathways (such as 1 O2 (surface-mediated electron transfer species). The radical pathway is renowned for its superior oxidation and mineralization capabilities. However, its inherent nonselectivity often triggers competitive side reactions with the background matrix, thus limiting its catalytic efficiency in complex water bodies. In contrast, the non-radical pathway exhibits strong selectivity and can effectively mitigate matrix interference. Paradoxically, however, its inherently low redox potential limits its ability to deeply mineralize recalcitrant organic matter. Therefore, the rational integration of radical and non-radical pathways to synergistically utilize their complementary advantages is crucial for developing efficient and universally applicable advanced water treatment technologies, but this remains a significant challenge.

[0004] Among them, ozone catalytic oxidation and Fenton-like technology have an inherent contradiction in the electronic characteristics requirements of the catalyst active sites during the initiation of free radical and non-free radical pathways: the initiation of free radical pathways (such as PAA generating •OH, PMS generating SO4) •- •OH usually requires the catalyst to provide electrons (electron-rich / reducing sites); while initiating non-radical pathways (such as forming surface-active complexes or triggering electron transfer processes) often requires the catalyst to accept electrons or provide coordination empty orbitals (electron-deficient / oxidizing sites). This leads to technical problems in existing catalysts when activating oxidants such as PAA / PMS / O3, such as single pathway, low electron utilization efficiency, and difficulty in synergistic interaction between radical and non-radical pathways. Summary of the Invention

[0005] To address the technical problems of existing catalysts in activating oxidants such as PAA / PMS / O3, including single pathway, low electron utilization efficiency, and difficulty in coordinating free radical and non-free radical pathways, this invention provides a transition metal-based heterojunction catalyst based on oxygen vacancy bridging, its preparation method, and its application in water treatment.

[0006] This invention employs the following technical solution: a transition metal-based heterojunction catalyst based on oxygen vacancy bridging, comprising: sequentially stacked metal oxides and corresponding zero-valent metals or corresponding mixed-state metal oxides; the interfacial spacing between the stacked metal oxides and the corresponding zero-valent metals or corresponding mixed-state metal oxides is at the atomic level, and a heterojunction rich in oxygen vacancies is formed between the stacked metal oxides and the corresponding zero-valent metals or corresponding mixed-state metal oxides; a built-in electric field is spontaneously formed at the interface of the heterojunction based on the Fermi level difference, and a pair of asymmetric electron-deficient sites and electron-rich sites are formed at the interface; oxygen vacancies act as electron bridges, forming continuous electron transfer channels between electron-deficient sites and electron-rich sites, thereby enabling electrons to circulate between electron-deficient sites and electron-rich sites, thus allowing the interface of the heterojunction to synergistically activate the oxidant based on both free radical and non-free radical electron transfer pathways.

[0007] As a further improvement of the present invention, the oxidant used for activation of the transition metal-based heterojunction catalyst includes any one or more of PAA, PMS, and O3.

[0008] As a further improvement of the present invention, when the transition metal base of the transition metal-based heterojunction catalyst is Cu, the transition metal-based heterojunction catalyst is Cu2O and Cu stacked sequentially.

[0009] As a further improvement of the present invention, when the transition metal group of the transition metal-based heterojunction catalyst is Fe, the transition metal-based heterojunction catalyst is Fe3O4 and Fe2O3 stacked sequentially.

[0010] As a further improvement of the present invention, when the transition metal group of the transition metal-based heterojunction catalyst is Mn, the transition metal-based heterojunction catalyst is MnO and Mn3O4 stacked sequentially.

[0011] This invention also provides a method for preparing a transition metal-based heterojunction catalyst based on oxygen vacancy bridging as described above, comprising: dissolving a transition metal salt in solvent one at a mass-to-volume ratio of 0.1-3 g: 10-100 mL to obtain a homogeneous solution one; dissolving a precipitant or reducing sugar in solvent two at a mass-to-volume ratio of 0.001-10 g: 10-100 mL to obtain a homogeneous solution two; mixing homogeneous solution one and homogeneous solution two and stirring until a uniform suspension is formed; subjecting the suspension to a hydrothermal reaction or coprecipitation reaction, and separating and washing the suspension after the hydrothermal reaction or coprecipitation reaction to obtain a precursor; reducing the precursor to obtain a product, and separating, washing and drying the product to obtain the transition metal-based heterojunction catalyst.

[0012] As a further improvement of the present invention, solvent one is water, ethanol, or a mixture of water and ethanol.

[0013] As a further improvement of the present invention, solvent two is water.

[0014] As a further improvement of the present invention, the transition metal salt includes any one of copper salt, iron salt and manganese salt.

[0015] As a further improvement of the present invention, the precipitant is any one of carbonate, bicarbonate or phosphate.

[0016] As a further improvement of the present invention, the reducing sugar is any one of glucose or a polyhydroxy compound.

[0017] As a further improvement of the present invention, the reduction process includes any of the following methods: Method 1: Mix the precursor with NaBH4 aqueous solution at a mass-volume ratio of 0.1~1g:10~50mL, and react at room temperature for 0.5-2 hours to obtain the product.

[0018] Method 2: Place the precursor in a hydrogen atmosphere or a mixture of hydrogen and argon, and perform a programmed temperature rise heat treatment at 300-500℃ for 1-4 hours to obtain the product.

[0019] Method 3: Mix the precursor with glucose in a molar ratio of 1:1 to 1:3, and then heat-treat in a hydrogen or a mixture of hydrogen and argon atmosphere at 400-700℃ for 1-5 hours to obtain the product.

[0020] Method 4: First, calcine the precursor at 600°C for 2 hours in an argon atmosphere to obtain an intermediate; then place the intermediate in a hydrogen or a mixture of hydrogen and argon atmosphere and treat it at 300°C for 1-5 hours to obtain the product.

[0021] As a further improvement of the present invention, if the transition metal salt is a copper salt or an iron salt, the suspension undergoes a hydrothermal reaction at a temperature of 120℃-140℃; if the transition metal salt is a manganese salt, the suspension undergoes a coprecipitation reaction, and the coprecipitation reaction process is as follows: the suspension is stirred at room temperature at a speed of 200-600 rpm for 2-8 hours.

[0022] The present invention also provides an application of a transition metal-based heterojunction catalyst based on oxygen vacancy bridging in water treatment, wherein the aforementioned transition metal-based heterojunction catalyst based on oxygen vacancy bridging is applied to degrade pollutants in organic wastewater.

[0023] As a further improvement of the present invention, the process of treating organic polluted wastewater based on the oxygen vacancy bridging transition metal-based heterojunction catalyst is as follows: Under normal temperature and neutral pH conditions, the transition metal-based heterojunction catalyst is added to the organic polluted wastewater at a mass-to-volume ratio of 0.005g~0.05g:100mL, wherein the organic polluted wastewater contains 0.1~0.6mmol / L of oxidant.

[0024] As a further improvement of the present invention, the oxidant includes one or more of persulfate, peracetic acid, or ozone.

[0025] As a further improvement of the present invention, the pollutants in the organic wastewater include one or more of sulfonamide antibiotics, endocrine disruptors, and dyes.

[0026] As a further improvement of the present invention, the concentration range of pollutants in the organic wastewater is 10-50 mg / L.

[0027] The technical solution provided by this invention has the following beneficial effects: (1) The oxygen vacancy bridging-based transition metal heterojunction catalyst provided by the present invention precisely constructs an oxygen vacancy electron bridge at the heterojunction interface. This structure significantly enhances the Fermi level difference effect of the heterojunction and promotes efficient electron transport. Through the synergistic effect of oxygen vacancy and the built-in electric field of the heterojunction, a continuous electronic energy level is formed inside the catalyst, which greatly improves the electron transfer capability and active site density of the transition metal heterojunction catalyst.

[0028] (2) The transition metal-based heterojunction catalyst based on oxygen vacancy bridging provided in this scheme introduces oxygen vacancies at the heterojunction interface to construct an electronic "bridge" connecting the interface and the electronic active sites of the asymmetric structure, thereby enabling the oxidant to be synergistically activated at the heterojunction interface based on both free radical and non-free radical electron transfer pathways. Specifically, oxygen vacancies introduce local defect energy levels, possessing excellent electron capture and transport capabilities. When constructed at the heterojunction interface, they can form a continuous and interconnected interfacial electron transfer channel. This channel not only effectively realizes rapid electron cycling between electron-deficient and electron-rich sites at the heterojunction interface, but also forms an asymmetric electronic structure through bridging, simultaneously matching the electron supply requirements of the free radical generation pathway and the electron acceptance and coordination requirements of the non-free radical pathway.

[0029] (3) The oxygen-vacancy-bridged transition metal-based heterojunction catalyst provided by this invention achieves bidirectional synergistic activation of oxidants such as PAA / PMS / O3 by bridging the heterojunction with oxygen vacancies, resulting in a dual-coordination configuration where the asymmetric electronic sites of the heterojunction form different sites in the oxidant. At the heterojunction interface, the electron-rich sites (Cu... 0 Fe 2+ Mn 2 + The free radical and non-free radical pathways are efficiently generated at the free radical sites; the defective electron sites simultaneously induce the formation of non-free radical electron transfer pathways. The free radical and non-free radical pathways work synergistically at the same catalytic interface, which significantly improves the selective removal efficiency and mineralization degree of recalcitrant organic pollutants such as sulfonamide antibiotics. Attached Figure Description

[0030] Figure 1 The present invention provides a flowchart of the preparation method of a transition metal-based heterojunction catalyst based on oxygen vacancy bridging.

[0031] Figure 2 For the present invention Figure 2 This is a photograph of a copper-based heterojunction catalyst taken under a transmission electron microscope.

[0032] Figure 3 For the present invention Figure 3 The image shows the X-ray diffraction pattern of a copper-based heterojunction catalyst.

[0033] Figure 4 The electron paramagnetic resonance spectra of the copper-based heterojunction catalyst at different activation times in the activation of peracetic acid in the present invention are shown.

[0034] Figure 5 This is a line graph showing the change in SMX concentration over time when different types of catalysts of the present invention are synergistically activated with peracetic acid to degrade SMX in organic polluted wastewater.

[0035] Figure 6 The graph shows the concentration of different pollutants in organic wastewater as a function of time when the copper-based heterojunction catalyst provided by this invention degrades them. Detailed Implementation

[0036] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0037] In the description of this invention, it should be noted that directional terms such as "center," "lateral," "longitudinal," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific scope of protection of this invention. The terms "first," "second," etc., in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "comprising" and "having," and any variations thereof, in the specification and claims of this invention, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0038] This embodiment provides a transition metal-based heterojunction catalyst based on oxygen vacancy bridging, comprising: sequentially stacked metal oxides and corresponding zero-valent metals or corresponding mixed-state metal oxides; the interface between the stacked metal oxides and the corresponding zero-valent metals, or the interface between the stacked metal oxides and the corresponding mixed-state metal oxides, must be tightly composited at the atomic scale. This allows the two materials to achieve near-gap, atomic-level contact and bonding at the interface, enabling the constructed transition metal-based heterojunction catalyst to form an oxygen-vacancy-rich heterojunction between the metal oxides and the corresponding zero-valent metals or the corresponding mixed-state metal oxides. Due to the initial Fermi level difference at the heterojunction interface, electrons spontaneously migrate, causing charge separation and spontaneously forming a built-in electric field, resulting in a pair of asymmetric electron-deficient and electron-rich sites at the interface. The built-in electric field can cause band bending at the heterojunction interface, ultimately achieving Fermi level alignment. When an external oxidant is present, the oxygen vacancies at the heterojunction interface can act as electron bridges, not only promoting the transfer of electrons from electron-rich sites to the oxidant via oxygen vacancies to efficiently generate free radicals, but also synergistically forming a dual-coordination configuration with the oxidant through electron-deficient sites, inducing non-radical electron transfer pathways. The built-in electric field provides the driving force for directional electron migration, allowing electron-rich and electron-deficient sites to dominate the free radical and non-radical pathways respectively, synergistically activating the oxidant at the interface. The principle that the electron-deficient and electron-rich sites based on the asymmetric electronic structure in this scheme can simultaneously satisfy the electron supply required for free radical generation and the electron acceptance / coordination requirements induced by the non-radical pathway is as follows: Regarding the free radical pathway, its free radicals (such as •OH, SO42-) •- The formation of free radicals typically requires an oxidizing agent molecule (such as persulfate PMS) to accept an electron, resulting in "electron reduction" and homolytic cleavage of chemical bonds. After accepting an electron, the OO bond of the oxidizing agent breaks, leading to the generation of a highly reactive free radical. For non-radical electron transfer pathways, non-radical species (such as singlet oxygen)... 1 O2, surface complexes, etc., are generally generated through electron rearrangement or energy transfer between the catalyst and the oxidant. On the electron-deficient site side, the empty orbital can coordinate with the lone pair electron of the oxidant, forming an intermediate complex. This coordination can elongate or polarize the chemical bonds within the oxidant molecule, inducing its transformation and generation. 1O2 can enable the catalyst-oxidant complex to act as an "electron transfer medium" that directly extracts electrons from pollutants, thereby initiating a non-radical pathway. In this scheme, the radical and non-radical electron transfer pathways do not operate independently, but are tightly coupled through an "electron bridge" formed by interfacial oxygen vacancies and a built-in electric field, achieving rapid bidirectional electron exchange. Therefore, this scheme introduces oxygen vacancies at the heterojunction interface to construct an electronic "bridge" connecting the interface and the electronically active sites of the asymmetric structure, enabling the heterojunction interface to simultaneously activate the oxidant based on both radical and non-radical electron transfer pathways. Specifically, oxygen vacancies introduce localized defect energy levels, possessing excellent electron capture and transport capabilities. Constructing them at the heterojunction interface forms a continuous and interconnected interfacial electron transfer channel. This channel not only effectively realizes rapid electron cycling between electron-deficient and electron-rich sites at the heterojunction interface, but also, relying on the asymmetric electronic structure formed by the bridge, synchronously matches the electron supply requirements of the radical generation pathway and the electron acceptance and coordination requirements of the non-radical pathway. In summary, the transition metal-based heterojunction catalyst provided by this scheme can construct oxygen vacancy electron bridges at the heterojunction interface and significantly enhance the electron transport rate between electron sites in the asymmetric structure of the heterojunction based on Fermi level alignment. This enables a dual-pathway synergistic drive of high oxidative reaction and high selectivity reaction at the heterojunction interface of a single active catalyst, thereby greatly improving the overall performance of the catalytic system.

[0039] Fermi level alignment is a thermodynamic equilibrium process in which electrons spontaneously migrate at the interface after two or more semiconductor materials are closely combined at the atomic scale until the Fermi levels of the entire system tend to be the same. During this process, electron migration triggers interfacial charge separation, leading to band bending and the formation of a built-in electric field. This built-in electric field serves as the core driving force for directional charge transfer and is also the basis for the electronic modulation effect of the heterojunction in the transition metal-based heterojunction catalyst provided in this scheme. This process can be understood as "electron potential energy balance": the Fermi level is the electrochemical potential energy benchmark for electrons in a semiconductor. Just like water flowing from a higher cup to a lower cup, electrons also spontaneously migrate from materials with higher Fermi levels to materials with lower Fermi levels until the "potential energy" of electrons on both sides is equal, that is, the Fermi level is flattened, and the net electron migration stops. At this point, the system reaches a thermodynamically stable state. Therefore, Fermi level alignment is a "potential energy equilibrium process" in heterojunctions, with the ultimate goal of forming a stable built-in electric field and space charge region. This provides the thermodynamic and kinetic basis for subsequent directional electron transfer at the interface and the electron bridging effect of oxygen vacancies. Only the space charge region generated through Fermi level alignment can form a directional built-in electric field, providing the driving force for the directional migration of interface electrons. This is the foundation for oxygen vacancies to act as "electron bridges" and achieve efficient charge transport. Furthermore, based on the fact that electron-deficient and electron-rich sites at the interface of the heterojunction after Fermi level alignment can be in thermodynamic equilibrium, random electron diffusion will not occur. This ensures that the radical and non-radical pathways can obtain a continuous and stable electron supply / acceptance, achieving synergistic activation of the oxidant by both pathways, thereby improving the activation performance of transition metal-based heterojunction catalysts.

[0040] The catalysts used for activation in transition metal-based heterojunction catalysts include any one or more of PAA, PMS, and O3. PAA is an abbreviation for peracetic acid, an organic peroxide with both oxidizing and disinfecting properties, and a commonly used green oxidant in advanced oxidation processes (AOPs). PMS is an abbreviation for permonosulfate, and O3 is an abbreviation for ozone. All three types of catalysts can synergistically work with the catalyst in reactions such as pollutant degradation and catalytic oxidation under the activation effect of the catalyst. The principles of synergistic catalysis between the three oxidants and the transition metal-based heterojunction catalyst of this scheme are described below. For PAA and the transition metal-based heterojunction catalyst, the metal on the surface of the transition metal-based heterojunction can synergistically activate PAA based on both free radical and non-free radical pathways, thereby improving the peroxy bond breaking efficiency of PAA and increasing the amount of active oxygen species generated. In addition, the oxygen vacancies at the interface of the transition metal-based heterojunction catalyst can act as electron bridges to accelerate electron transfer on the catalyst surface, promote the valence state cycling of metal ions, and avoid passivation of active sites, thereby achieving the purpose of continuous activation of PAA. Furthermore, the asymmetric electronic sites of transition metal-based heterojunction catalysts can simultaneously meet the electron supply (reduction of PAA) and electron acceptance (coordination of PAA) requirements during PAA activation, achieving synergy between radical and non-radical pathways. This balances high oxidizing power and high selectivity in oxidation reactions, thereby improving the catalytic degradation performance of transition metal-based heterojunction catalysts. For PMS and transition metal-based heterojunction catalysts, the asymmetric electronic structure (i.e., electron-deficient and electron-rich sites) of the transition metal-based heterojunction catalyst allows both catalysts and PMS to simultaneously meet the electron supply and coordination requirements for PMS activation. This enables the synergistic activation of PMS via both radical and non-radical pathways, generating a variety of highly oxidizing active substances and providing a dual pathway guarantee for subsequent pollutant degradation. For ozone and transition metal-based heterojunction catalysts, the essence of the synergistic effect between ozone and the transition metal-based heterojunction catalyst provided in this scheme is that the heterojunction can provide an efficient, stable and controllable active center for ozone activation, while ozone can provide the catalyst with strong oxidizing properties and active species precursors, thereby achieving the purpose of degrading pollutants in water through the synergistic effect of transition metal-based heterojunction catalyst and activator.

[0041] The transition metal group in the transition metal-based heterojunction catalyst can be any of Fe, Cu, or Mn. When the transition metal group is Cu, the catalyst can be a sequentially stacked Cu₂O and Cu. When the transition metal group is Fe, the catalyst can be a sequentially stacked Fe₃O₄ and Fe₂O₃. When the transition metal group is Mn, the catalyst can be a sequentially stacked MnO and Mn₃O₄. The transition metal heterojunction catalysts constructed using these materials can all form a heterojunction with an interface rich in oxygen vacancies. A built-in electric field spontaneously forms at the interface of the heterojunction based on the Fermi level difference, and a pair of asymmetric electron-deficient and electron-rich sites are formed at the interface. The electron-rich sites tend to donate electrons to oxidants (such as the OO bond in PAA), leading to homolytic cleavage and the generation of highly oxidizing free radicals (such as •OH). Electron-deficient sites tend to accept electrons from oxidants or polarize oxidant molecules through coordination, inducing internal electron rearrangement and generating highly selective non-radical species (such as...). 1 O2) or directly through interfacial electron transfer oxidizes pollutants. Oxygen vacancy bridging ensures that these two seemingly contradictory processes can proceed rapidly and synergistically, forming a highly efficient catalytic cycle. This enables the cyclic transfer of electrons between electron-deficient and electron-rich sites, allowing the heterojunction interface to simultaneously activate the oxidant based on both free radical and non-free radical electron transfer pathways. In summary, the transition metal-based heterojunction catalyst of this invention bridges the heterojunction with oxygen vacancies, enabling the asymmetric electron sites of the heterojunction to form a dual-coordination configuration with different sites in the oxidant, achieving bidirectional synergistic activation of oxidants such as PAA / PMS / O3. At the heterojunction interface, electron-rich sites (Cu... 0 Fe 2+ Mn 2+ The free radical and non-free radical pathways are efficiently generated at the free radical sites; the defective electron sites simultaneously induce the formation of non-free radical electron transfer pathways. The free radical and non-free radical pathways work synergistically at the same catalytic interface, which significantly improves the selective removal efficiency and mineralization degree of recalcitrant organic pollutants such as sulfonamide antibiotics.

[0042] Furthermore, the "interfacial oxygen vacancy bridging heterojunction asymmetric electron sites" strategy proposed in this invention establishes a novel dual-pathway synergistic catalytic mechanism. This design principle can be extended to other metal oxide / metal heterojunction systems, providing an innovative solution for developing highly efficient catalysts for oxidants such as PAA / PMS / O3 and addressing the common problem of low oxidant utilization efficiency in Fenton-like technologies. Moreover, the transition metal-based heterojunction catalyst of this scheme is based on its oxygen-vacancy-bearing heterojunction, and the special structure of oxygen vacancies acting as electron bridges to promote interfacial charge transport allows the transition metal-based catalyst to simultaneously activate oxidants such as PAA / PMS / O3 through both free radical and non-free radical electron transfer pathways. Through oxygen vacancy bridging, a continuous energy level structure of "electron donor-electron shuttle-electron acceptor" is constructed at the heterojunction interface, thereby achieving "bidirectional electron transfer" of oxidant molecules at the same active interface. Finally, the transition metal-based heterojunction catalytic system of this invention can operate efficiently under normal temperature and neutral pH conditions. Transition metal-based heterojunction catalysts exhibit excellent stability, with metal ion dissolution of less than 0.5 mg / L. After five cycles, the catalytic efficiency is maintained at over 90%, demonstrating good environmental friendliness and economic feasibility.

[0043] Based on the aforementioned transition metal-based heterojunction catalysts based on oxidation vacancy bridging, this embodiment also provides a method for preparing transition metal-based heterojunction catalysts based on oxidation vacancy bridging. Please refer to [link / reference]. Figure 1 It includes the following steps: (I) Preparation of precursors (1.1) Dissolve the transition metal salt in solvent one at a mass-volume ratio of 0.1~3g:10~100mL to obtain homogeneous solution one. (Can you provide the volume ratio range of transition metal salt to solvent one?)

[0044] (1.2) Dissolve the precipitant or reducing sugar in solvent two at a mass-volume ratio of 0.001~10g:10~100mL to obtain homogeneous solution two. (Can you provide the volume ratio range of precipitant and reducing sugar to solvent two?)

[0045] (1.3) Mix homogeneous solution one and homogeneous solution two and stir until a uniform suspension is formed. Perform hydrothermal reaction or coprecipitation reaction on the suspension, and separate and wash the suspension after hydrothermal reaction or coprecipitation treatment to obtain the precursor.

[0046] In step (1.1), the mass in the mass-to-volume ratio refers to the mass of the transition metal salt, and the volume refers to the volume of solvent one. The transition metal salt may include any one of copper, iron, and manganese salts. Solvent one may be water, ethanol, or a mixture of water and ethanol. When it is a copper salt, it may be CuCl2·2H2O, solvent one may be anhydrous ethanol, and the precursor obtained from this copper salt is Cu2O / Cu. When it is an iron salt, it may be FeCl3, solvent one may be water, and the precursor obtained from this iron salt is Fe3O4 / Fe2O3. When it is a manganese salt, it may be MnSO4·H2O, solvent one may be anhydrous ethanol, and the precursor obtained from this manganese salt is MnO / Mn3O4.

[0047] In step (1.2), the mass in the mass-to-volume ratio refers to the mass of the precipitant or reducing sugar, and the volume refers to the volume of solvent two. The precipitant can be any one of carbonate, bicarbonate, or phosphate. When it is a carbonate, it can be Na₂CO₃; when it is a bicarbonate, it can be NH₄HCO₃. When it is a phosphate, it can be NH₄H₂PO₄. The reducing sugar can be glucose (C₆H₂O). 12 O6) or polyhydroxy compounds. Solvent 2 can be water.

[0048] In step (1.3), when the transition metal salt is a copper or manganese salt, the resulting intermediate product suspension can undergo a hydrothermal reaction at a temperature of 120℃-140℃ for 12-48 hours. When the transition metal salt is a manganese salt, the resulting intermediate product suspension can undergo a coprecipitation reaction. The specific operation of the coprecipitation reaction is as follows: the suspension is stirred at room temperature for 2-8 hours at a stirring speed of 200-600 rpm.

[0049] (ii) Construction of oxygen vacancies The precursor is reduced to obtain the product, which is then separated, washed, and dried to obtain the transition metal-based heterojunction catalyst.

[0050] The restoration process in step (II) includes any one of the following four methods: Method 1: Mix the precursor with an aqueous solution of NaBH4 at a mass-to-volume ratio of 0.1-1 g: 10-50 mL, and react at room temperature for 0.5-2 hours to obtain the product. The concentration of NaBH4 can be 0.1-1 M.

[0051] Method 2: Place the precursor in a hydrogen atmosphere or a mixture of hydrogen and argon, and perform a programmed temperature rise heat treatment at 300-500℃ for 1-4 hours to obtain the product.

[0052] Method 3: Mix the precursor and glucose uniformly at a molar ratio of 1:1 to 1:3, and then heat-treat in a hydrogen or a mixture of hydrogen and argon atmosphere at 400℃-700℃ for 15 hours to obtain the product.

[0053] Method 4: First, calcine the precursor at 600°C for 2 hours in an argon atmosphere to obtain an intermediate; then place the intermediate in a hydrogen or a mixture of hydrogen and argon atmosphere and treat it at 300°C for 1-5 hours to obtain the product.

[0054] In addition, the product can be dried in step (ii) by vacuum drying at a temperature of 50℃-100℃ for 6-24 hours.

[0055] The above operations can be used to obtain asymmetric electron sites based on oxygen vacancy-bridged heterojunctions. O Transition metal-based heterojunction catalysts (-HAS). If the transition metal salt is a copper salt, the resulting transition metal-based heterojunction catalyst is V. O -HAS-Cu2O / Cu. If the transition metal salt is an iron salt, the resulting transition metal-based heterojunction catalyst is V. O -HAS-Fe3O4 / Fe2O3. If the transition metal salt is a manganese salt, the resulting transition metal-based heterojunction catalyst can be V. O -HAS-MnO / Mn3O4.

[0056] The preparation processes of transition metal-based heterojunction catalysts based on different transition metal salts are described below. When the transition metal salt is a copper salt, a copper-based heterojunction catalyst based on oxygen vacancy bridging is obtained. A method for preparing a copper-based heterojunction catalyst based on oxygen vacancy bridging is as follows: (1) Dissolve 1.83g CuCl2·2H2O in 60 mL of anhydrous ethanol and sonicate for 20 minutes to obtain a homogeneous solution A. (2) Dissolve 6.0g Na2CO3 and 2.4g C6H 12O6 (glucose) was dissolved in 60 mL of ultrapure water to obtain mixed solution B. (3) Under stirring at 400-700 rpm, solution A was slowly added dropwise to solution B, and stirring was continued for 30 minutes to form a uniform suspension. (4) The suspension obtained in step (3) was transferred to a 150 mL high-pressure reactor lined with polytetrafluoroethylene and hydrothermally reacted at 120 °C for 8 hours. After natural cooling, the precipitate was collected by centrifugation and washed three times with deionized water and ethanol to obtain the precursor. (5) The precursor obtained in step (4) was dispersed in a 50 mL NaBH4 aqueous solution with a volume molar concentration of 1 M and a volume of 50 mL and reduced at room temperature for 1.0 hour. (6) The product after treatment in step (5) was centrifuged and washed three times each with deionized water and ethanol, and the solid was vacuum dried at 80 °C for 12 hours to obtain a catalyst with abundant interfacial oxygen vacancies, labeled as V. O -HAS-Cu2O / Cu.

[0057] When the transition metal salt is an iron salt, an iron-based heterojunction catalyst based on oxide vacancy bridging is obtained. The preparation method of an iron-based heterojunction catalyst based on oxide vacancy bridging is as follows: (1) Dissolve 0.19g FeCl3 in 30mL of ultrapure water and sonicate for 20 minutes to obtain homogeneous solution A. (2) Dissolve 0.006g NH4H2PO4 in 30mL of ultrapure water to obtain solution B. (3) Under stirring at 400-700rpm, slowly add solution B to solution A and continue stirring for 30 minutes to form a uniform suspension. (4) Transfer the suspension obtained in step (3) to a 100mL high-pressure reactor lined with polytetrafluoroethylene and hydrothermally react at 180℃ for 12 hours. After natural cooling, collect the precipitate by centrifugation and wash it three times each with deionized water and ethanol to obtain the Fe2O3 precursor. (5) Mix 0.1g of the precursor obtained in step (4) with 2.0g of glucose solid reducing agent and place the mixture in a ceramic crucible. Then, heat-treat the mixture at 600 ℃ for 3 hours under an argon / hydrogen mixed atmosphere (gas flow rate 100 mL / min). (6) Allow the product treated in step (5) to cool naturally to room temperature. After grinding, obtain a magnetic V with abundant interfacial oxygen vacancies. O -HAS-Fe3O4 / Fe2O3 heterocatalyst.

[0058] When the transition metal salt is a manganese salt, a manganese-based heterojunction catalyst based on oxidation vacancy bridging is obtained. The preparation method of a manganese-based heterojunction catalyst based on oxidation vacancy bridging is as follows: (1) Dissolve 2.37g of manganese sulfate monohydrate (MnSO4·H2O) in a mixed solvent of 100 mL of deionized water and 20 mL of anhydrous ethanol, and sonicate for 20 minutes to obtain homogeneous solution A. (2) Dissolve 0.11g of ammonium bicarbonate (NH4HCO3) in 30 mL of ultrapure water to obtain solution B. (3) Under stirring at 400-700 rpm, slowly add solution B to solution A, and continue stirring for 3 hours to form a uniform white suspension. (4) Filter the suspension obtained in step (3), and wash it three times each with deionized water and ethanol, and dry the obtained solid under vacuum at 70°C for 12 hours to obtain the precursor. (5) The precursor obtained in step (4) is placed in a tube furnace and calcined at 600 °C for 2 hours under an argon atmosphere to obtain a MnO intermediate; then the obtained MnO intermediate is placed in a hydrogen / argon mixed atmosphere and calcined again at 300 °C for 5 hours. (6) The product after step (5) is naturally cooled to room temperature to obtain a MnO / Mn3O4 heterojunction catalyst with abundant interfacial oxygen vacancies, labeled as V. O -HAS-MnO / Mn3O4.

[0059] Based on this, this embodiment also provides an application of a transition metal-based heterojunction catalyst based on oxygen vacancy bridging in water treatment. The aforementioned transition metal-based heterojunction catalyst based on oxygen vacancy bridging is applied to degrade pollutants in organic wastewater. The process of treating organic wastewater using the transition metal-based heterojunction catalyst based on oxygen vacancy bridging is as follows: Under ambient temperature and neutral pH conditions, the transition metal-based heterojunction catalyst is added to 100 mL of organic wastewater at a mass-to-volume ratio of 0.005 g to 0.05 g, where the organic wastewater contains 0.1 to 0.6 mmol / L of oxidant.

[0060] The mass-to-volume ratio of the transition metal-based heterojunction catalyst to the volume of the organic wastewater is 0.005 g to 0.05 g: 100 mL. When the volume of the organic wastewater is 100 mL, the concentration of the oxidant in the wastewater can be 0.1 mM to 0.6 mM.

[0061] Oxidants include one or more of persulfate, peracetic acid, or ozone. The initial concentration of the oxidant can be 0.05 mM to 5 mM; the ozone gaseous concentration can be 10 mg / L to 30 mg / L, and the ozone liquid concentration can be 2 mg / L to 6 mg / L. When gaseous ozone is selected as the input source of the oxidant, its concentration can be 10 mg / L to 30 mg / L; specifically, ozone can be introduced into the water, and the final concentration of dissolved ozone in the water can be stabilized within the range of 2 mg / L to 6 mg / L. The catalyst dosage concentration can be 0.5 g / L to 2.0 g / L. Pollutants in organic wastewater include one or more of sulfonamide antibiotics, fluoroquinolone antibiotics, endocrine disruptors, and dyes. The concentration range of pollutants in organic wastewater is 10-50 mg / L. The ambient temperature can be 25℃, and the neutral pH can be 7.

[0062] Performance testing To verify the performance of the transition metal-based heterojunction catalyst based on oxygen vacancy bridging provided in this embodiment, the technicians conducted the following verification experiment.

[0063] Sample preparation: A copper-based heterojunction catalyst based on oxygen vacancy bridging was prepared as follows: 1.83 g CuCl2·2H2O was dissolved in 60 mL of anhydrous ethanol and sonicated for 20 minutes to obtain homogeneous solution A. (2) 6.0 g Na2CO3 and 2.4 g C6H 12 O6 (glucose) was dissolved in 60 mL of ultrapure water to obtain mixed solution B. (3) Solution A was slowly added dropwise to solution B while stirring at 500 rpm for 30 minutes to form a uniform suspension. (4) The suspension obtained in step (3) was transferred to a 150 mL high-pressure reactor lined with polytetrafluoroethylene and hydrothermally reacted at 120 °C for 8 hours. After natural cooling, the precipitate was collected by centrifugation and washed three times with deionized water and ethanol to obtain the precursor. (5) The precursor obtained in step (4) was dispersed in a 50 mL NaBH4 aqueous solution with a volume molar concentration of 1 M and a volume of 50 mL and reduced at room temperature for 1.0 hour. (6) The product after treatment in step (5) was centrifuged and washed three times each with deionized water and ethanol. The solid was vacuum dried at 80 °C for 12 hours to obtain a catalyst with abundant interfacial oxygen vacancies, labeled as V. O -HAS-Cu2O / Cu.

[0064] (1) Transmission electron microscopy experiment The prepared copper-based heterojunction catalyst was observed under a transmission electron microscope, and the results were obtained. Figure 2 . Figure 2 The image shows a copper-based heterojunction catalyst photographed using a transmission electron microscope. Figure 2Figure (a) shows the morphology of the copper-based heterojunction catalyst. Figure 2 Figure (b) shows the lattice diagram of the copper-based heterojunction catalyst. Through analysis of... Figure 2 Analysis of Figure (a) reveals that the copper-based heterojunction catalyst exhibits a hollow microsphere structure, with numerous spherical nanoparticles randomly agglomerated to form the outer shell of the hollow microspheres. Channels for mass exchange exist between the crystallites of the shell walls. During catalysis, the reaction substrate can interact with the catalyst through these channels. Furthermore, treatment with NaBH4 alleviated the agglomeration of the Cu2O / Cu hollow microspheres, and a large number of small particles appeared on the outer shell, indicating that more active sites were exposed on the catalyst. Looking further... Figure 2 Figure (b) shows four regions with different lattice structures, with lattice spacings of 2.08 nm, 2.37 nm, and 2.97 nm, respectively. These correspond to the Cu(111), Cu2O(111), and Cu2O(110) crystal planes, indicating that the catalyst obtained after treatment with NaBH4 has a significant Cu2O / Cu heterojunction structure.

[0065] (2) X-ray diffraction analysis: The precursor in the prepared sample was dispersed in a 50 mL NaBH4 aqueous solution with a volume molality of 1 M. The solution was then calcined at room temperature under an argon / hydrogen mixed atmosphere (gas flow rate 100 mL / min). The precursors under different reduction times were analyzed using an XRD diffractometer to obtain the results. Figure 3 Through the analysis of Figure 3 Analysis revealed two sets of diffraction peaks for Cu₂O and Cu in the catalyst sample, confirming their coexistence. Cu₂O exhibited a simple cubic structure (Pn-3m, JCPDS number 78-2076), with corresponding diffraction peak positions of 29.51°, 36.41°, 42.31°, 61.41°, and 73.5°, while Cu exhibited a face-centered cubic structure (Fm-3m, JCPDSs number 04-0836), with corresponding diffraction peak positions of 43.41°, 50.41°, and 74.11°. With prolonged NaBH₄ reduction treatment time, the peak intensity of the Cu₂O / Cu diffraction peaks significantly decreased, while the full width at half maximum (FWHM) slightly increased. This was attributed to lattice distortion caused by oxygen vacancies in the catalyst. Furthermore, when the treatment time was extended to 3 h, a significant transformation in the lattice structure of Cu₂O / Cu occurred.

[0066] (3) Electron paramagnetic resonance (EPR) experiment The copper-based heterojunction catalyst obtained from the prepared sample was used to activate peracetic acid, and copper-based heterojunction catalysts with different activation times were obtained. The copper-based heterojunction catalysts with different activation times were analyzed using an electron paramagnetic resonance spectrometer. Figure 4.

[0067] The EPR test parameters were as follows: at room temperature, the central magnetic field strength was 3520 G, the scan width was 100 G, the scan frequency was 9.751 GHz, the microwave energy was 20 mW, the scan time was 30 s, and the number of scans was 3. The experimental conditions were set as follows: PAA = 0.2 mmol / L, V0-Cu2O / Cu = 0.05 g / L, SMX = 10 mg / L, DMPO = 100 mM, and TEMP = 100 mM.

[0068] Through the Figure 4 Analysis shows that, Figure 4 Figure (a) shows the activation of TEMP- in peracetic acid by a copper-based heterojunction catalyst. 1 Electron paramagnetic resonance spectrum of O2; Figure 4 Figure (b) shows the electron paramagnetic resonance spectrum of DMPO-•OH during the activation of peracetic acid by a copper-based heterojunction catalyst; Figure 4 Figure (c) shows the DMPO / O2 ratio during the activation of peracetic acid by a copper-based heterojunction catalyst. •- Electron paramagnetic resonance spectra of DMPO-CH3C(=O)OO•.

[0069] Through the Figure 4 Analysis revealed that, firstly, the V was detected using EPR spectroscopy with DMPO and TEMP as spin trapping agents. O The ROSs (RO•, •OH) generated in the -HAS-Cu2O / Cu / PAA system 1 O2 and O2 •- V O TEMPO was not observed in the HAS-Cu2O / Cu / PAA catalytic system. 1 The EPR signal of O2 indicates 1 O2 generation is limited. However, the characteristic peaks of the DMPO-•OH complex were observed, indicating that V... O -HAS-Cu2O / Cu catalyzes the formation of •OH from PAA. O2 was investigated using DMPO as a trapping agent. •- The formation of DMPO-O2 was observed. •- The characteristic peaks indicate that V O The -HAS-Cu2O / Cu / PAA system produced O2. •- (i.e., superoxide radicals). Through Figure 4 The electron paramagnetic resonance spectrum directly confirmed V O The successful construction of oxygen vacancies at the heterojunction interface of -HAS-Cu2O / Cu and their crucial role in the activation of peracetic acid (PAA). Figure 4As shown, the V based on oxygen vacancy bridging prepared by the method of the present invention O The HAS-Cu2O / Cu heterojunction catalyst exhibits a series of characteristic free radical signals in the presence of PAA, clearly revealing its synergistic activation mechanism of multiple active species. Specifically, the catalyst prepared by the "heterogeneous structure construction-controllable vacancy introduction" strategy proposed in this invention (especially the samples treated for 1.0 h and 2.0 h) can synergistically generate [a specific type of catalyst]. 1 O2, O2 •- And multiple reactive species, mainly organic peroxide free radicals. This provides direct experimental evidence for the catalytic oxidation mechanism of "synergistic effect of free radicals and non-free radicals" in this invention, and clarifies the important role of interfacial oxygen vacancy structure in targeted activation of PAA and regulation of reaction pathways, thus laying the mechanistic foundation for achieving efficient and highly selective pollutant degradation or disinfection processes. Therefore, through the "heterogeneous structure construction-controllable vacancy introduction" strategy proposed in this invention, V O An oxygen-rich, vacancy-rich active interface structure was constructed at the HAS-Cu2O / Cu interface. This structure not only promotes the generation of various reactive oxygen species, but more importantly, it enables the direct and efficient activation of PAA molecules, thus providing a key structural and mechanistic basis for the catalyst's excellent oxidation performance.

[0070] (4) Degradation efficiency of SMX in organic wastewater by different catalysts The specific treatment processes of organic polluted wastewater by the different transition metal-based heterojunction catalysts prepared in this scheme are described based on different transition metal bases.

[0071] Experimental Group 1: The steps for treating organic wastewater using a copper-based heterojunction catalyst are as follows: At 25℃ and pH 7, 100 mL of SMX solution containing 10 mg / L was added to the reactor, followed by peracetic acid and 0.005 g of oxygen vacancy-bridged copper-based heterojunction catalyst, so that the concentration of peracetic acid was 0.2 mM and the concentration of copper-based heterojunction catalyst was 0.05 g / L.

[0072] Experimental Group 2: The steps for treating organic wastewater using an iron-based heterojunction catalyst are as follows: At 25℃ and pH 7, 100 mL of SMX solution containing 10 mg / L was added to the reactor, followed by peracetic acid and 0.005 g of iron-based heterojunction catalyst based on oxygen vacancy bridging, so that the concentration of peracetic acid was 0.2 mM and the concentration of iron-based heterojunction catalyst was 0.05 g / L.

[0073] Experiment Group 3: The steps for treating organic wastewater using a manganese-based heterojunction catalyst are as follows: At 25℃ and pH 7, 100 mL of SMX solution containing 10 mg / L was added to the reactor, followed by peracetic acid and 0.005 g of oxygen vacancy-bridged manganese-based heterojunction catalyst, so that the concentration of peracetic acid was 0.2 mM and the concentration of manganese-based heterojunction catalyst was 0.05 g / L.

[0074] Comparative Example: A group of copper-based catalysts without hydrogen calcination were prepared according to the above-mentioned method for preparing copper-based heterojunction catalysts. The specific preparation process of the copper-based catalyst is as follows: 0.83g CuCl2·2H2O was dissolved in 60 mL of anhydrous ethanol and ultrasonically treated for 20 minutes to obtain homogeneous solution A. (2) 6.0g Na2CO3 and 2.4g C6H 12 O6 (glucose) was dissolved in 60 mL of ultrapure water to obtain mixed solution B. (3) Solution A was slowly added dropwise to solution B while stirring at 500 rpm, and stirring was continued for 30 minutes to form a uniform suspension. (4) The suspension obtained in step (3) was transferred to a 150 mL high-pressure reactor lined with polytetrafluoroethylene and hydrothermally reacted at 120 °C for 8 hours. After natural cooling, the precipitate was collected by centrifugation and washed three times with deionized water and ethanol to obtain the copper-based catalyst.

[0075] The steps for treating organic wastewater using the copper-based catalyst provided in the comparative example are as follows: Under conditions of 25℃ and pH 7, 100 mL of SMX solution containing 10 mg / L was added to the reactor, followed by peracetic acid and 0.005 g of copper-based catalyst, so that the concentration of peracetic acid was 0.2 mM and the concentration of copper-based catalyst was 0.05 g / L.

[0076] The treatment effects of the catalysts provided in Experimental Groups 1, 2, 3, and the comparative example on SMX in organic wastewater were detected by high-performance liquid chromatography (HPLC). The results are as follows: Figure 5 As shown.

[0077] Through the Figure 5Analysis revealed that the copper-based heterojunction catalyst in Experimental Group 1 achieved a 98% degradation efficiency of SMX in the organic wastewater after 60 minutes of treatment; the iron-based heterojunction catalyst in Experimental Group 2 also achieved a 98% degradation efficiency; and the manganese-based heterojunction catalyst in Experimental Group 3 achieved a 98% degradation efficiency. In contrast, the copper-based catalyst in the comparative study showed a 42% degradation efficiency for SMX in the organic wastewater after 60 minutes of treatment. This demonstrates that the oxygen-vacancy-bridged transition metal-based heterojunction catalyst provided in this scheme exhibits excellent degradation efficiency for SMX. Furthermore, data analysis from Experimental Group 1 and the control group also indicates that introducing oxygen vacancy structures at the heterojunction interface plays a crucial role in enhancing the catalytic activity of peracetic acid and strengthening pollutant degradation performance.

[0078] (5) Degradation efficiency of copper-based heterojunction catalysts for different pollutants in organic wastewater The steps for treating organic wastewater using the copper-based heterojunction catalyst prepared from the product sample are as follows: 100 mL of organic wastewater is added to the reactor at 25 °C and pH 7, followed by peracetic acid and 0.005 g of oxygen vacancy-bridged copper-based heterojunction catalyst, so that the concentration of peracetic acid is 0.2 mM and the concentration of copper-based heterojunction catalyst is 0.05 g / L.

[0079] The concentrations of SMX, BPA, MO, RhB, PPL, Resorcinol, and BA in organic wastewater were determined by high-performance liquid chromatography (HPLC) over time. Figure 6 . Figure 6 This diagram illustrates the degradation effect of copper-based heterojunction catalysts on different pollutants in organic wastewater. (The image shows the degradation efficiency of these catalysts.) Figure 6 It can be seen that after 60 minutes of degradation of organic pollutants in wastewater by the copper-based heterojunction catalyst provided in this scheme, the concentrations of SMX, BPA, MO, RhB, PPL, Resorcinol, and BA in the wastewater all decreased significantly. This proves that the copper-based heterojunction catalyst provided in this scheme has a good degradation effect on pollutants such as SMX, BPA, MO, RhB, PPL, Resorcinol, and BA in organic pollutants in wastewater.

[0080] The basic principles, main features, and advantages of this invention have been described above. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection claimed by this invention is defined by the appended claims and their equivalents.

Claims

1. A transition metal-based heterojunction catalyst based on oxygen vacancy bridging, characterized in that, It includes: Sequentially stacked metal oxides and their corresponding zero-valent metals or their corresponding mixed-state metal oxides; The interfacial spacing between the stacked metal oxides and the corresponding zero-valent metals or the corresponding mixed-state metal oxides is at the atomic level, and a heterojunction rich in oxygen vacancies is formed between the stacked metal oxides and the corresponding zero-valent metals or the corresponding mixed-state metal oxides. A built-in electric field is spontaneously formed at the interface of the heterojunction based on the Fermi level difference, and a pair of asymmetric electron-deficient sites and electron-rich sites are formed at the interface. The oxygen vacancies act as electron bridges to form continuous electron transfer channels between the electron-deficient sites and the electron-rich sites, thereby enabling electrons to circulate between the electron-deficient sites and the electron-rich sites. This allows the interface of the heterojunction to synergistically activate the oxidant based on both free radical and non-free radical electron transfer pathways.

2. The transition metal-based heterojunction catalyst based on oxygen vacancy bridging as described in claim 1, characterized in that, The oxidants used for activation of the transition metal-based heterojunction catalyst include any one or more of PAA, PMS, and O3.

3. The transition metal-based heterojunction catalyst based on oxygen vacancy bridging as described in claim 1, characterized in that, When the transition metal base of the transition metal-based heterojunction catalyst is Cu, the transition metal-based heterojunction catalyst is Cu2O and Cu stacked sequentially. And / or, when the transition metal group of the transition metal-based heterojunction catalyst is Fe, the transition metal-based heterojunction catalyst is Fe3O4 and Fe2O3 stacked sequentially; And / or, when the transition metal group of the transition metal-based heterojunction catalyst is Mn, the transition metal-based heterojunction catalyst is MnO and Mn3O4 stacked sequentially.

4. A method for preparing a transition metal-based heterojunction catalyst based on oxygen vacancy bridging as described in any one of claims 1-3, characterized in that, It includes: A transition metal salt is dissolved in solvent one at a mass-to-volume ratio of 0.1-3 g: 10-100 mL to obtain homogeneous solution one; a precipitant or reducing sugar is dissolved in solvent two at a mass-to-volume ratio of 0.001-10 g: 10-100 mL to obtain homogeneous solution two; homogeneous solution one and homogeneous solution two are mixed and stirred until a uniform suspension is formed; the suspension is subjected to hydrothermal reaction or coprecipitation reaction treatment, and the suspension after hydrothermal reaction or coprecipitation treatment is separated and washed to obtain the precursor; The precursor is reduced to obtain the product, which is then separated, washed, and dried to obtain the transition metal-based heterojunction catalyst.

5. The method for preparing the transition metal-based heterojunction catalyst based on oxygen vacancy bridging as described in claim 4, characterized in that, The solvent is water, ethanol, or a mixture of water and ethanol. And / or, the second solvent is water; And / or, the transition metal salt includes any one of copper salt, iron salt, and manganese salt; And / or, the precipitant is any one of carbonate, bicarbonate or phosphate; And / or, the reducing sugar is any one of glucose or a polyhydroxy compound.

6. The method for preparing the transition metal-based heterojunction catalyst based on oxygen vacancy bridging as described in claim 4, characterized in that, The restoration process includes any of the following methods: Method 1: Mix the precursor with NaBH4 aqueous solution at a mass-volume ratio of 0.1~1g:10~50mL, and react at room temperature for 0.5-2 hours to obtain the product; Method 2: Place the precursor in a hydrogen or hydrogen-argon mixture atmosphere and perform programmed temperature rise heat treatment at 300-500℃ for 1-4 hours to obtain the product; Method 3: Mix the precursor and glucose uniformly at a molar ratio of 1:1 to 1:3, and then heat-treat in a hydrogen or a mixed atmosphere of hydrogen and argon at 400-700℃ for 1-5 hours to obtain the product. Method 4: First, calcine the precursor at 600°C for 2 hours in an argon atmosphere to obtain an intermediate; then place the intermediate in a hydrogen or a mixture of hydrogen and argon atmosphere and treat it at 300°C for 1-5 hours to obtain the product.

7. The method for preparing the transition metal-based heterojunction catalyst based on oxygen vacancy bridging as described in claim 4, characterized in that, If the transition metal salt is a copper or iron salt, the suspension undergoes a hydrothermal reaction at a temperature of 120℃-140℃; if the transition metal salt is a manganese salt, the suspension undergoes a coprecipitation reaction, the coprecipitation reaction process being as follows: the suspension is stirred at 200-600 rpm for 2-8 hours at room temperature.

8. The application of a transition metal-based heterojunction catalyst based on oxygen vacancy bridging in water treatment, characterized in that, The oxygen vacancy-bridged transition metal-based heterojunction catalyst as described in any one of claims 1-3 is used to degrade pollutants in organic wastewater.

9. The application of the oxygen vacancy-bridged transition metal-based heterojunction catalyst as described in claim 8 in water treatment, characterized in that, The process of treating organic polluted wastewater using the transition metal-based heterojunction catalyst based on oxygen vacancy bridging is as follows: Under normal temperature and neutral pH conditions, the transition metal-based heterojunction catalyst is added to the organic polluted wastewater at a mass-to-volume ratio of 0.005g~0.05g:100mL, wherein the organic polluted wastewater contains 0.1~0.6mmol / L of oxidant.

10. The application of the oxygen vacancy-bridged transition metal-based heterojunction catalyst as described in claim 8 in water treatment, characterized in that, The oxidant includes one or more of persulfate, peracetic acid, or ozone; And / or, the pollutants in the organic wastewater include one or more of sulfonamide antibiotics, endocrine disruptors, and dyes; And / or, the concentration range of pollutants in the organic wastewater is 10-50 mg / L.

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