Molybdenum oxide heterointerface composite electrode and preparation method thereof

Abstract

The application discloses a molybdenum oxide heterojunction composite electrode and a preparation method thereof, relates to the technical field of wastewater treatment and resource utilization, and discloses a molybdenum oxide heterojunction composite electrode preparation method, which comprises the following steps: mixing and grinding a conductive polymer precursor and a molybdenum source to obtain a mixture, wherein the molybdenum source generates MoO x after pyrolysis treatment; under an inert atmosphere, the mixture is subjected to pyrolysis treatment to obtain a composite powder; the composite powder, a binder and a solvent are mixed to obtain a slurry; and the slurry is loaded on a current collector to prepare the molybdenum oxide heterojunction composite electrode. The embodiment of the application prepares a capacitive deionization electrode material with high capacity, low energy consumption and excellent ion selectivity, which can selectively and reversibly recover ammonia nitrogen and phosphate from wastewater and sewage simultaneously.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment and resource utilization technology, and in particular to a molybdenum oxide heterostructure composite electrode and its preparation method. Background Technology

[0002] With the accelerating pace of global industrialization and urbanization, large quantities of high-concentration organic wastewater, including urban domestic sewage, wastewater from large-scale livestock and poultry farming, and anaerobic fermentation broth from organic waste, are continuously generated. These wastewaters generally contain high concentrations of ammonia nitrogen (NH4+). + ) and phosphate (PO4) 3- If untreated nitrogen and phosphorus are discharged directly into natural water bodies, they can easily cause eutrophication, leading to a series of serious ecological and environmental problems such as algal blooms, oxygen depletion, and decreased biodiversity, posing a significant threat to aquatic ecosystems and the safety of human drinking water. Meanwhile, nitrogen and phosphorus are indispensable nutrients in agricultural production and core raw materials for fertilizer manufacturing. Global phosphate rock resources are non-renewable, with limited reserves and uneven distribution; while the ammonia synthesis process consumes enormous amounts of energy and is a significant source of carbon emissions. Therefore, selectively recovering nitrogen and phosphorus from wastewater can not only reduce environmental pollution but also has significant resource value.

[0003] To achieve simultaneous recovery of nitrogen and phosphorus from wastewater, researchers both domestically and internationally have developed various technological approaches. Capacitive Deionization (CDI), as an emerging electrochemical water treatment method, has attracted widespread attention due to its advantages such as low energy consumption, environmental friendliness, and ease of operation. Its basic principle is to use an external electric field to drive ions in the solution to migrate towards an electrode with the opposite charge and adsorb onto the electric double layer at the electrode / electrolyte interface, thereby achieving ion removal. However, the electrode materials used in conventional CDI technologies (such as activated carbon) have poor ion selectivity, making it difficult to achieve efficient and selective separation and recovery of specific ions from complex wastewater. Summary of the Invention

[0004] The main objective of this application is to provide a molybdenum oxide heterostructure composite electrode and its preparation method, which yields a capacitive deionization electrode material with high capacity, low energy consumption and excellent ion selectivity, capable of selectively and reversibly recovering ammonia nitrogen and phosphate from wastewater and sewage simultaneously.

[0005] To achieve the above objectives, this application provides a method for preparing a molybdenum oxide heterojunction composite electrode, comprising the following steps:

[0006] A conductive polymer precursor is mixed and ground with a molybdenum source to obtain a mixture, wherein the molybdenum source generates MoO after pyrolysis. x ;

[0007] The mixture was subjected to pyrolysis under an inert atmosphere to obtain composite powder.

[0008] The composite powder, binder, and solvent are mixed to obtain a slurry;

[0009] The slurry was loaded onto a current collector to prepare a molybdenum oxide heterostructure composite electrode.

[0010] In one embodiment, the conductive polymer precursor includes at least one of PPy-DBSA, PANI-DBSA, and PPy-PSS.

[0011] In one embodiment, the molybdenum source includes: (NH4)2MoO4 and (NH4)6Mo7O. 24 At least one of MoCl5 and (NH4)2MoS4.

[0012] In one embodiment, the mass ratio between the conductive polymer precursor and the molybdenum source is (1~4):(4~1).

[0013] In one embodiment, the molybdenum oxide heterojunction composite electrode has a loading of 2-6 mg / cm³. 2 .

[0014] In one embodiment, the pyrolysis treatment includes: heating to 500-700°C at a heating rate of 5-15°C / min, holding at that temperature for 2-6 hours, and then cooling to room temperature.

[0015] In one embodiment, the adhesive comprises at least one of PVDF, PTFE, and CMC / SBR;

[0016] And / or, the solvent includes at least one of NMP, DMF, and DMSO;

[0017] And / or, the current collector includes at least one of graphite paper, carbon cloth, and Ti mesh.

[0018] In one embodiment, the composite powder: conductive agent: binder ratio in the slurry is (70~90):(0~15):(5~15) by mass.

[0019] In one embodiment, the step of loading the slurry onto a current collector to prepare a molybdenum oxide heterojunction composite electrode includes:

[0020] Apply the slurry to the current collector with a coating thickness of 50~150 μm;

[0021] Molybdenum oxide heterostructure composite electrode was prepared by vacuum drying at 40-80 °C for 6-12 h.

[0022] To achieve the above objectives, this application provides a molybdenum oxide heterostructure composite electrode, which is prepared by the molybdenum oxide heterostructure composite electrode preparation method described above.

[0023] This application provides a method for preparing a molybdenum oxide heterojunction composite electrode, comprising: mixing and grinding a conductive polymer precursor with a molybdenum source to obtain a mixture, wherein the molybdenum source generates MoO after pyrolysis treatment. x Therefore, by pyrolyzing the mixture under an inert atmosphere, a hierarchical porous active composite powder with a carbon matrix as the conductive framework and rich in MoOx (including α-MoO2 and α-MoO3) heterogeneous interfaces is constructed. The composite powder, binder, and solvent are then mixed to obtain a slurry. This slurry is loaded onto a current collector to prepare a molybdenum oxide heterogeneous interface composite electrode, which can be used as a deionization electrode material. In this embodiment, the electrode constructs a "heterogeneous interface-dual-path" synergistic mechanism. During pyrolysis, abundant heterogeneous interfaces are formed between the α-MoO2 and α-MoO3 crystal phases formed in situ. The MoOx in the α-MoO2 lattice... 6+ / Mo 5+ Redox pairs exhibit rapid and reversible electron transfer, providing a significant pseudocapacitive effect for NH4+. + It exhibits excellent dynamic capture capability and electrochemical selectivity; at the same time, the α-MoO3 surface is rich in Mo 6+ The site can coordinate with PO4 through PO-Mo inner globule coordination. 3- Strong chemisorption is formed, achieving highly selective phosphate enrichment. The two action pathways share the Mo 4d electron band, forming a reversible valence state cycling system. This not only significantly improves the electrode's specific capacity and reaction kinetics but also maintains low interfacial impedance and high coulombic efficiency during long-term cycling, ensuring the electrode's stability and regeneration capability. Secondly, synergistic performance enhancement is achieved through defect engineering. During pyrolysis, in MoO... x The oxygen vacancies introduced at the carbon-carbon interface have a dual function. On the one hand, they serve as Lewis acid sites, enhancing the resistance to PO4. 3-The coordination adsorption capacity of oxygen atoms enhances the PO-Mo bond strength. Furthermore, acting as an electron buffer, it regulates the interfacial electron distribution, lowers the charge transfer barrier, and further amplifies the pseudocapacitive contribution and overall conductivity of the material, thereby synergistically improving the electrode's adsorption capacity and response speed for target ions. Additionally, the carbon framework formed by the pyrolysis of the conductive polymer precursor, together with the flower-shaped secondary MoOx particles, constructs a hierarchical pore system with micropores, narrow mesopores, and macropores. This structure not only provides a large specific surface area, offering abundant active sites for ion adsorption, but more importantly, it significantly shortens the electron transport path in the conductive carbon network and the ion diffusion path in the electrolyte, achieving efficient electron-ion synergistic migration. This effectively alleviates mass transfer polarization under high current density, improving the electrode's rate performance and desalination rate. This application successfully prepared a capacitive deion electrode material with high selectivity, high capacity, low impedance, and easy regeneration characteristics through a three-in-one material control strategy of "heterogeneous interface design - defect engineering - multi-level channel construction". It can selectively and reversibly recover ammonia nitrogen and phosphate from wastewater and sewage simultaneously, and has significant environmental benefits and resource utilization potential. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method for preparing a molybdenum oxide heterostructure composite electrode according to the embodiments of this application;

[0025] Figure 2 This is an XRD test result diagram of the PM31 electrode in the embodiments of this application;

[0026] Figure 3 This is a scanning electron microscope image of the composite powder used in the PM31 electrode in the embodiments of this application;

[0027] Figure 4 This is the EDS energy spectrum of the composite powder used in the PM31 electrode in the embodiments of this application;

[0028] Figure 5 This is a transmission electron microscope (TEM) image of the composite powder used in the PM31 electrode in the embodiments of this application;

[0029] Figure 6 This is a graph showing the oxygen vacancy test results of the PM31 electrode in the embodiments of this application;

[0030] Figure 7 This is a graph showing the 500-cycle charge-discharge curve of the PM31 electrode in the embodiments of this application;

[0031] Figure 8 The graph shows the adsorption test results of the PM31 electrode in single solutions with different concentration gradients in the embodiments of this application.

[0032] Figure 9In the PM31 electrode cycling process of this application embodiment, NH4 + The diagram shows the energy consumption and charge efficiency for charge removal.

[0033] Figure 10 In the embodiments of this application, PO4 is generated during the PM31 electrode cycling process. 3- The diagram shows the energy consumption and charge efficiency for charge removal.

[0034] Figure 11 The graph shows the test results of the adsorption and desorption of different ions by the PM31 electrode in the embodiments of this application.

[0035] Figure 12 This is a graph showing the test results of the selectivity coefficient of the PM31 electrode for different ions in the embodiments of this application;

[0036] Figure 13 The above are XPS spectra of Mo before and after adsorption in the CDI system in this application embodiment;

[0037] Figure 14 The above are XPS spectra of O elements before and after adsorption in the CDI system in this application embodiment;

[0038] Figure 15 The above are XPS spectra of N elements before and after adsorption in the CDI system in this application embodiment;

[0039] Figure 16 The XPS spectra and total XPS spectra of P element before and after adsorption in the CDI system of this application embodiment are shown below.

[0040] Figure 17 The above are XPS spectra of S element before and after adsorption in the CDI system in this application embodiment;

[0041] Figure 18 The above are XPS spectra of C elements before and after adsorption in the CDI system in this application embodiment;

[0042] Figure 19 In the embodiments of this application, the PM31 electrode is used for NH4 + A schematic diagram of the local density of states analysis results;

[0043] Figure 20 In the embodiments of this application, the PM31 electrode is used for Na + A schematic diagram of the local density of states analysis results;

[0044] Figure 21 In the embodiments of this application, the PM31 electrode is used for PO4. 3- A schematic diagram of the local density of states analysis results;

[0045] Figure 22 In the embodiments of this application, the PM31 electrode is used for Cl -A schematic diagram of the local density of states analysis results;

[0046] Figure 23 In the embodiments of this application, the PM31 electrode is used for NH4 + A schematic diagram of Bader charge transfer;

[0047] Figure 24 In the embodiments of this application, the PM31 electrode is used for PO4. 3- A schematic diagram of Bader charge transfer.

[0048] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0050] The embodiments of the molybdenum oxide heterojunction composite electrode and its preparation method of this application are disclosed in detail below with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0051] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0052] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0053] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0054] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the technical solution of this application is further described below in conjunction with the accompanying drawings and embodiments. However, this application is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims made in this application.

[0055] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0056] In conventional technologies, CDI systems mostly employ activated carbon electrodes, which primarily rely on the electro-bilayer adsorption mechanism and lack the ability to recognize specific ions. In complex wastewater systems, this ability is limited for ions with similar hydration radii (such as NH4+).+ with Na + It has almost no separation ability, extremely poor selectivity, and low adsorption capacity, making it difficult to meet the needs of practical applications.

[0057] This application provides a method for preparing a molybdenum oxide heterojunction composite electrode. The method involves mixing and grinding a conductive polymer precursor with a molybdenum source to obtain a mixture. The molybdenum source is then pyrolyzed to generate MoO. x Therefore, by pyrolyzing the mixture under an inert atmosphere, a hierarchical porous active composite powder with a carbon matrix as the conductive framework and rich in MoOx (including α-MoO2 and α-MoO3) heterogeneous interfaces is constructed. The composite powder, binder, and solvent are then mixed to obtain a slurry. This slurry is loaded onto a current collector to prepare a molybdenum oxide heterogeneous interface composite electrode, which can be used as a deionization electrode material. In this embodiment, the electrode constructs a "heterogeneous interface-dual-path" synergistic mechanism. During pyrolysis, abundant heterogeneous interfaces are formed between the α-MoO2 and α-MoO3 crystal phases formed in situ. The MoOx in the α-MoO2 lattice... 6+ / Mo 5+ Redox pairs exhibit rapid and reversible electron transfer, providing a significant pseudocapacitive effect for NH4+. + It exhibits excellent dynamic capture capability and electrochemical selectivity; at the same time, the α-MoO3 surface is rich in Mo 6+ The site can coordinate with PO4 through PO-Mo inner globule coordination. 3- Strong chemisorption is formed, achieving highly selective phosphate enrichment. The two action pathways share the Mo 4d electron band, forming a reversible valence state cycling system. This not only significantly improves the electrode's specific capacity and reaction kinetics but also maintains low interfacial impedance and high coulombic efficiency during long-term cycling, ensuring the electrode's stability and regeneration capability. Secondly, synergistic performance enhancement is achieved through defect engineering. During pyrolysis, in MoO... x The oxygen vacancies introduced at the carbon-carbon interface have a dual function. On the one hand, they serve as Lewis acid sites, enhancing the resistance to PO4. 3-The coordination adsorption capacity of oxygen atoms enhances the PO-Mo bond strength. Furthermore, acting as an electron buffer, it regulates the interfacial electron distribution, lowers the charge transfer barrier, and further amplifies the pseudocapacitive contribution and overall conductivity of the material, thereby synergistically improving the electrode's adsorption capacity and response speed for target ions. Additionally, the carbon framework formed by the pyrolysis of the conductive polymer precursor, together with the flower-shaped secondary MoOx particles, constructs a hierarchical pore system with micropores, narrow mesopores, and macropores. This structure not only provides a large specific surface area, offering abundant active sites for ion adsorption, but more importantly, it significantly shortens the electron transport path in the conductive carbon network and the ion diffusion path in the electrolyte, achieving efficient electron-ion synergistic migration. This effectively alleviates mass transfer polarization under high current density, improving the electrode's rate performance and desalination rate. This application successfully prepared a capacitive deion electrode material with high selectivity, high capacity, low impedance, and easy regeneration characteristics through a three-in-one material control strategy of "heterogeneous interface design - defect engineering - multi-level channel construction". It can selectively and reversibly recover ammonia nitrogen and phosphate from wastewater and sewage simultaneously, and has significant environmental benefits and resource utilization potential.

[0058] The first embodiment of this application provides a method for preparing a molybdenum oxide heterointerface composite electrode, referring to... Figure 1 This includes the following steps:

[0059] Step S10: The conductive polymer precursor is mixed and ground with a molybdenum source to obtain a mixture, wherein the molybdenum source generates MoO after pyrolysis treatment. x ;

[0060] In one feasible embodiment, a conductive polymer precursor is provided, and the conductive polymer precursor is mixed and ground with a molybdenum source to obtain a mixture.

[0061] Optionally, the grinding method can be dry grinding or ball milling, with a grinding time of 5–30 min. For example, the grinding time can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, etc. Dry grinding / ball milling is a mechanochemical process that breaks up the agglomeration of the two powders through the strong impact, compression, and shearing action of the grinding media (such as mortar and pestle, or grinding balls in a grinding jar). This mechanical force forces the two powder particles with different properties to be repeatedly broken, mixed, and redispersed, ultimately ensuring that the molybdenum source and the conductive polymer precursor are in full and uniform contact at the microscale. Simultaneously, this facilitates the in-situ generation of MoO during pyrolysis. x Nanoparticles are uniformly embedded in the carbon matrix to create conditions that enhance the chemical affinity between the two precursors, thus "pre-activating" the pyrolysis reaction.

[0062] Optionally, the conductive polymer precursor includes at least one of PPy-DBSA, PANI-DBSA, and PPy-PSS.

[0063] PPy-DBSA, or polypyrrole-dodecylbenzenesulfonic acid, is a type of carbon that, upon pyrolysis, forms amorphous carbon rich in defects and micropores, known as MoO. x DBSA provides conductive support and a high specific surface area. As a bulky anionic dopant, its long alkyl chain acts as a soft template during polymerization and pyrolysis, facilitating the formation of porous, loose carbon structures and promoting subsequent mass transfer. Simultaneously, the DBSA molecule contains sulfonate and benzene rings. During pyrolysis, sulfur can be doped into the carbon framework to form sulfur-doped carbon, altering the electron cloud density of carbon and enhancing its conductivity and affinity for specific ions. The benzene ring structure, on the other hand, promotes the formation of a more stable carbon structure. Furthermore, the decomposition of DBSA can create pores in situ, contributing to the formation of hierarchical channels and increasing the specific surface area. The oxygen or sulfur atoms in the sulfonate groups may coordinate with Mo species before or during pyrolysis, promoting uniform dispersion and interfacial bonding of Mo.

[0064] PANI-DBSA, or polyaniline-dodecylbenzenesulfonic acid, is rich in nitrogen atoms. After pyrolysis, most of the nitrogen remains in the carbon framework, forming nitrogen-doped carbon. Nitrogen doping significantly improves the electrical conductivity, surface polarity, and electrochemical activity of carbon materials. Furthermore, its positively charged carbon sites (due to nitrogen's higher electronegativity than carbon) are more effective against anions (such as PO4). 3- It exhibits stronger electrostatic attraction, enhancing the selective adsorption of phosphate. Simultaneously, the nitrogen atoms in the PANI framework are excellent Lewis basic sites, which may react with Mo during pyrolysis. 6+ Coordination with Lewis acidic metal ions helps to achieve uniform dispersion of Mo and the formation of the Mo-NC interface.

[0065] PPy-PSS, or polypyrrole-polystyrene sulfonic acid, uses PPy as the carbon source and PSS as a high-molecular-weight polyelectrolyte. PSS has a large molecular weight and decomposes to produce a large amount of gas during pyrolysis, exhibiting strong pore-forming ability, thereby increasing the specific surface area of ​​the electrode and improving its adsorption capacity. Furthermore, PSS contains a large number of sulfonic acid groups and benzene ring / ether bonds, which, after pyrolysis, allow for the co-doping of sulfur and oxygen, further modulating the electronic structure and surface chemistry of carbon, and optimizing the electrode's response to cations (NH4+). + ) and anions (PO4) 3- The adsorption performance of ).

[0066] For example, a PPy-DBSA conductive polymer precursor was prepared by chemical oxidative polymerization at 0 °C using dodecylbenzenesulfonic acid (DBSA) as a soft template.

[0067] Optionally, the molybdenum source includes: (NH4)2MoO4, (NH4)6Mo7O 24 At least one of MoCl5 and (NH4)2MoS4. The molybdenum source selected in the embodiments of this application generates MoO after pyrolysis treatment. x It mainly includes α-MoO2 and α-MoO3, and can form a tight interface with the carbon-based framework. Abundant heterogeneous interfaces are formed between the α-MoO2 and α-MoO3 crystal phases, with Mo in the α-MoO2 lattice... 6+ / Mo 5+ Redox pairs exhibit rapid and reversible electron transfer, providing a significant pseudocapacitive effect for NH4+. + It exhibits excellent dynamic capture capability and electrochemical selectivity; at the same time, the α-MoO3 surface is rich in Mo 6+ The site can coordinate with PO4 through PO-Mo inner globule coordination. 3- Strong chemisorption is formed, achieving highly selective phosphate enrichment. The two action pathways share the Mo 4d electron band, forming a reversible valence state cycling system, which not only significantly improves the specific capacity and reaction kinetics of the electrode, but also maintains low interfacial impedance and high coulombic efficiency during long-term cycling, ensuring the stability and regeneration capability of the electrode.

[0068] In one feasible embodiment, the mass ratio of the conductive polymer precursor to the molybdenum source is (1~4):(4~1). For example, the mass ratio of the conductive polymer precursor to the molybdenum source is 1:4, 1:3, 1:2, 1:1, 2:3, 2:1, 3:4, 3:2, 3:1, 4:1, 4:3, etc. If the amount of conductive polymer precursor added is too small, the carbon source (from the polymer) is insufficient to completely "encapsulate" or "disperse" all the molybdenum species, making it difficult to form abundant "MoO". x The " / carbon" heterostructure weakens the "dual-pathway synergy" effect, leading to a decrease in the electrode's specific capacity, selectivity, and reaction kinetics. Conversely, if the amount of molybdenum source added is too small, the generated MoO2... x The particles are few in number and low in density, which cannot provide enough active sites to efficiently capture NH4. + and PO4 3- The electrode may exhibit non-selective adsorption behavior similar to ordinary activated carbon, and therefore cannot achieve adsorption of NH4. + and PO4 3- This enables efficient and selective simultaneous recycling. Furthermore, the embodiments of this application control the amount of conductive polymer precursor and molybdenum source added to ensure that the molybdenum source is fully and uniformly dispersed in the carbon matrix, forming high-density, small-sized, uniformly distributed MoOx nanoparticles, thereby maximizing the heterointerface area and active site density.

[0069] Optionally, the mass ratio of the conductive polymer precursor to the molybdenum source is 3:1.

[0070] Step S20: The mixture is subjected to pyrolysis treatment under an inert atmosphere to obtain composite powder;

[0071] In one feasible embodiment, the mixture is placed in a quartz boat and subjected to pyrolysis treatment under an inert atmosphere, including: heating to 500-700 ℃ at a heating rate of 5-15 ℃ / min, holding at that temperature for 2-6 h, and then cooling to room temperature to obtain a composite powder of α-MoO3 / α-MoO2 embedded N,S co-doped carbon framework.

[0072] Optionally, the heating rate for pyrolysis treatment can be 5 ℃ / min, 6 ℃ / min, 7 ℃ / min, 8 ℃ / min, 9 ℃ / min, 10 ℃ / min, 11 ℃ / min, 12 ℃ / min, 13 ℃ / min, 14 ℃ / min, 15 ℃ / min, etc. If the heating rate is too fast, the internal temperature gradient of the precursor will be large, resulting in uneven heating inside and outside, and the carbonization process will be insufficient, leading to low graphitization degree of the carbon skeleton, numerous defects, and poor electrical conductivity. If the heating rate is too slow, it will take too long, resulting in low efficiency and the possibility of unnecessary side reactions. Therefore, the embodiments of this application select a heating rate of 5~15 ℃ / min to achieve a relative balance between heat and mass transfer, avoid severe thermal stress and pressure shock, facilitate the formation of a material with a complete structure and well-developed pores, and provide sufficient time for the uniform dispersion and gradual nucleation of Mo species, promoting small-sized, highly dispersed MoO. x The formation of nanoparticles enables the gradient carbonization of polymers, resulting in a carbon skeleton with good conductivity and moderate defects.

[0073] Optionally, the target temperature for pyrolysis treatment can be 500 ℃, 520 ℃, 540 ℃, 560 ℃, 580 ℃, 600 ℃, 620 ℃, 640 ℃, 680 ℃, 700 ℃, etc. In this embodiment, a suitable holding temperature was selected to ensure complete carbonization of the polymer, forming a carbon skeleton with good electrical conductivity; controllable reduction of Mo species was achieved, allowing α-MoO3 and α-MoO2 to coexist, forming abundant heterogeneous interfaces. Simultaneously, an appropriate amount of oxygen vacancies were generated to serve as Lewis acid sites and electron buffers.

[0074] Optionally, the holding time for pyrolysis treatment can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, etc. The embodiments of this application selected a suitable holding time to ensure that all pyrolysis reactions are fully completed, the material structure is stable, and the uniform distribution of Mo species and interface formation are promoted.

[0075] Optionally, the inert atmosphere can be N2 or Ar, at a rate of 50~200 mL / min.

[0076] Step S30: Mix the composite powder, binder and solvent to obtain a slurry;

[0077] In one feasible embodiment, the composite powder, binder and solvent are mixed and magnetically stirred for 8 to 12 hours to form a slurry.

[0078] Optionally, a conductive agent can be further added to the slurry, that is, the composite powder, binder, conductive agent and solvent are mixed to obtain the slurry.

[0079] Optionally, the binder includes at least one of PVDF, PTFE, and CMC / SBR. The binder can bond the active material (i.e., composite powder) and conductive agent particles together and firmly adhere them to the current collector, maintaining the integrity of the electrode structure.

[0080] Optionally, the conductive agent includes at least one of Super P, conductive carbon black, and graphene. The addition of a conductive agent helps reduce electrode internal resistance and improve conductivity and rate performance.

[0081] Optionally, the solvent includes at least one of NMP, DMF, and DMSO.

[0082] In one feasible embodiment, the composite powder: conductive agent: binder ratio in the slurry is (70~90):(0~15):(5~15) by mass. For example, the composite powder: conductive agent: binder ratio in the slurry is 8:1:1, 8:2:1, 9:1:3, 8:3:5, 7:1:1, 6:1:1, 8:0:1, etc.

[0083] Step S40: Load the slurry onto the current collector to obtain a molybdenum oxide heterostructure composite electrode.

[0084] In one feasible embodiment, the slurry is coated onto the current collector with a coating thickness of 50~150 μm and then vacuum dried at 40~80 °C for 6~12 h to obtain a molybdenum oxide heterointerface composite electrode.

[0085] The current collector is a key component in the electrode that carries the active material coating, collects and conducts current. It does not participate in the electrochemical reaction itself, but it must have high conductivity, good chemical / electrochemical stability, strong adhesion to the active layer, and a certain mechanical strength.

[0086] Optionally, the current collector includes at least one of graphite paper, carbon cloth, and Ti mesh.

[0087] Optionally, the coating thickness of the slurry can be 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, etc. The coating thickness determines the areal loading of active material on the electrode per unit area and the overall thickness of the electrode. The embodiments of this application select a moderate coating thickness, so that the electrode achieves a balance between high areal capacity and good mass transfer / conductivity, realizing high overall performance, namely high capacity, good rate capability, and long cycling performance.

[0088] Optionally, the drying temperature can be 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, etc.

[0089] Optionally, the drying time can be 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, etc.

[0090] In one feasible embodiment, the loading of the molybdenum oxide heterojunction composite electrode is 2~6 mg / cm³. 2 For example, the loading of the molybdenum oxide heterojunction composite electrode is 2 mg / cm³. 2 2.5 mg / cm 2 3 mg / cm 2 3.5 mg / cm 2 4mg / cm 2 4.5 mg / cm 2 5 mg / cm 2 5.5 mg / cm 2 6 mg / cm 2 If the loading is too low, the total amount of active material per unit area is small, resulting in a small amount of desalination per electrode during application, requiring frequent regeneration, leading to low practical application efficiency and low device volumetric energy / mass density. Conversely, if the loading is too high, the electrode layer becomes thicker, significantly extending the diffusion path of ions in the electrode pores. Although the total mass increases, the effective specific capacity decreases, and the areal capacity growth tends to saturate or even decline. The embodiments of this application maximize the utilization of active material while ensuring mass transfer efficiency by setting an appropriate loading.

[0091] Optionally, the molybdenum oxide heterojunction composite electrode has a loading of 3.9–4.1 mg / cm³. 2 .

[0092] Optionally, the molybdenum oxide heterojunction composite electrode prepared in the embodiments of this application can be used in environments containing high concentrations of coexisting ions (such as Na+). + K + Ca 2+ Mg 2+Cl - SO4 2- Even in complex wastewater systems (such as those containing NH4), it can still maintain its ability to control NH4. + and PO4 3- Its highly selective identification and efficient simultaneous removal capabilities eliminate the need for any additional chemical precipitants, thus avoiding secondary pollution and sludge generation. The entire recycling process relies solely on electrochemical drive, resulting in low energy consumption and simple regeneration. For example, ion desorption and electrode regeneration can be achieved through voltage reversal, enabling the clean and recyclable recovery of nitrogen and phosphorus resources.

[0093] In this embodiment, a molybdenum oxide heterojunction composite electrode was fabricated, which can be used as a capacitive deionization electrode material. This electrode establishes a synergistic mechanism of "heterojunction-dual pathway". During pyrolysis, abundant heterojunctions are formed between the α-MoO2 and α-MoO3 crystal phases that are formed in situ, wherein the Mo in the α-MoO2 lattice... 6+ / Mo 5+ Redox pairs exhibit rapid and reversible electron transfer, providing a significant pseudocapacitive effect for NH4+. + It exhibits excellent dynamic capture capability and electrochemical selectivity; at the same time, the α-MoO3 surface is rich in Mo 6+ The site can coordinate with PO4 through PO-Mo inner globule coordination. 3- Strong chemisorption is formed, achieving highly selective phosphate enrichment. The two action pathways share the Mo 4d electron band, forming a reversible valence state cycling system. This not only significantly improves the electrode's specific capacity and reaction kinetics but also maintains low interfacial impedance and high coulombic efficiency during long-term cycling, ensuring the electrode's stability and regeneration capability. Secondly, synergistic performance enhancement is achieved through defect engineering. During pyrolysis, in MoO... x The oxygen vacancies introduced at the carbon-carbon interface have a dual function. On the one hand, they serve as Lewis acid sites, enhancing the resistance to PO4. 3-The coordination adsorption capacity of oxygen atoms enhances the PO-Mo bond strength. Furthermore, acting as an electron buffer, it regulates the interfacial electron distribution, lowers the charge transfer barrier, and further amplifies the pseudocapacitive contribution and overall conductivity of the material, thereby synergistically improving the electrode's adsorption capacity and response speed for target ions. Additionally, the carbon framework formed by the pyrolysis of the conductive polymer precursor, together with the flower-shaped secondary MoOx particles, constructs a hierarchical pore system with micropores, narrow mesopores, and macropores. This structure not only provides a large specific surface area, offering abundant active sites for ion adsorption, but more importantly, it significantly shortens the electron transport path in the conductive carbon network and the ion diffusion path in the electrolyte, achieving efficient electron-ion synergistic migration. This effectively alleviates mass transfer polarization under high current density, improving the electrode's rate performance and desalination rate. This application successfully prepared a capacitive deion electrode material with high selectivity, high capacity, low impedance, and easy regeneration characteristics through a three-in-one material control strategy of "heterogeneous interface design - defect engineering - multi-level channel construction". It can selectively and reversibly recover ammonia nitrogen and phosphate from wastewater and sewage simultaneously, and has significant environmental benefits and resource utilization potential.

[0094] In order to enable those skilled in the art to clearly understand the details and operations of the above embodiments of this application, and to demonstrate the significant improvement in performance of the embodiments of this application, the above technical solutions are illustrated below through multiple embodiments.

[0095] Example 1

[0096] (1) Mix PPy-DBSA and (NH4)2MoO4 at a mass ratio of 3:1 and dry grind for 20 min to obtain a mixture;

[0097] (2) The mixing zone was placed in a quartz boat and subjected to pyrolysis under N2 atmosphere. The temperature was increased to 600 ℃ at a heating rate of 10 ℃ / min, held for 4 h, and then cooled to room temperature to obtain composite powder.

[0098] (3) Mix PVDF and NMP to prepare a 20 mg / mL binder solution. Mix the composite powder, conductive carbon black and binder solution at a mass ratio of 8:1:1 and stir magnetically for 12 h to prepare a slurry.

[0099] (4) The slurry was coated onto graphite paper to a thickness of 110 μm and dried under vacuum at 40 °C for 8 h to obtain a molybdenum oxide heterointerface composite electrode (denoted as PM31 electrode), wherein the loading was 4 mg / cm³. 2 .

[0100] XRD tests were performed on the PM31 electrode in Example 1 above, and the results are as follows: Figure 2XRD analysis confirmed the composite structure of α-MoO2 / α-MoO3 phases with nanoscale grains, with the main peaks matching those of α-MoO2 (PDF#76-1807) and α-MoO3 (PDF#99-0080), respectively. The broad, diffuse peaks at 20–30° originate from the N,S co-doped amorphous carbon framework. The molybdenum oxide peaks show significant broadening and weakening, indicating the formation of nanocrystals, defects / strain, and heterogeneous interfaces, which provide high-density active sites for pseudocapacitance and coordination adsorption.

[0101] Furthermore, referring to Figure 3 This is a scanning electron microscope (SEM) image of the composite powder used in the PM31 electrode. Flower-shaped secondary particles with a diameter of approximately 0.5–1.5 μm are visible, which shorten the ion diffusion distance while preserving fluid channels. (Reference) Figure 4 The image shows the EDS spectrum of the composite powder used in the PM31 electrode, revealing a uniform distribution of C, O, N, Mo, and S elements. (Refer to...) Figure 5 This is a transmission electron microscope (TEM) image of the composite powder used in the PM31 electrode. Further analysis of the TEM image reveals that α-MoO3(130) / (112) and α-MoO2(-101) / (-201) are nested "face-to-face" within the same nanodomain, forming a continuous heterogeneous interface with electron passages. The remaining areas are other orientations and defect bands, proving that MoO... x The nanoscale domains exhibit a polycrystalline synergistic distribution.

[0102] Furthermore, the specific surface area of ​​the PM31 electrode was measured, and it reached a high of 388.24 m². 2 / g.

[0103] Furthermore, oxygen vacancy tests were performed on the PM31 electrode, and the results were referenced... Figure 6 The g-factor ≈ 2.0031 corresponding to the signal peak indicates oxygen vacancy enrichment.

[0104] Furthermore, in a three-electrode system, a silver / silver chloride electrode (Ag / AgCl) was used as the reference electrode, a platinum sheet electrode as the counter electrode, and a 1 mol / L Na₂SO₄ solution as the electrolyte. The PM31 electrode from Example 1 was subjected to 500 charge-discharge cycles. The results were compared with those obtained in [the original text]. Figure 7 As can be seen, after 500 accelerated cycles, the PM31 electrode still retains a specific capacitance of 96.7%. This indicates that the electrode has excellent cycling stability and long lifespan, and can resist dissolution and pulverization in complex water environments, providing a reliable guarantee for industrial applications.

[0105] Furthermore, the PM31 electrode was used as the anode in a CDI system, and the adsorption capacity of the PM31 electrode in single solutions with different concentration gradients was tested (constant voltage 1.2V, 20min). The results are referenced. Figure 8It can be seen that under ideal conditions, the PM31 electrode is effective against NH4+. + and PO4 3- The maximum adsorption capacities are as high as 73.6 mg / g and 84.0 mg / g, respectively, demonstrating excellent adsorption performance.

[0106] Furthermore, the charge efficiency and energy consumption of the CDI system equipped with the PM31 electrode were tested under multiple cycles in a 10-fold diluted biogas slurry (V=200mL). The concentrations of the main ions in the biogas slurry are shown in Table 1 below. For NH4+... + The results refer to Figure 9 For PO4 3- The test results are referenced. Figure 10 The cycle mode was ±1.2V, with 20 min adsorption / 15 min desorption and a flow rate of 15 mL / min. -1 As can be seen, the system remained stable over 40 adsorption-desorption cycles. NH4 + Adsorption charge efficiency CE NH4+ After a 5-10 cycle of "survival period," it enters a plateau, fluctuating generally within the 0.67-0.75 range. PO4 3- Adsorption charge efficiency CE PO43- The value was approximately 0.53 in the second cycle, stabilized at 0.60-0.67 in cycles 6-16, and gradually decreased and stabilized at 0.53-0.55 after 20 cycles. Correspondingly, the energy consumption per unit mass of the adsorption section fluctuated low over multiple cycles: SEC N = 3.07 ± 0.27 kWh·kg -1 -N, SEC P =5.27 ± 0.41 kWh·kg -1- P (mean ± SD). The above results indicate that the PM31 electrode exhibits good cycling stability and energy utilization efficiency within an adsorption window of ± 1.2 V and 20 min.

[0107] Table 1:

[0108]

[0109] Furthermore, the energy consumption of the PM31 electrode of this application was compared with that of existing electrodes, and the results are shown in Table 2 below. It is evident that the PM31 electrode in Example 1 of this application has significant advantages compared to existing high-energy-consuming products.

[0110] Table 2:

[0111]

[0112] Furthermore, the adsorption and desorption capacities of the PM31 electrode for different ions were tested in the aforementioned CDI system, and the results are as follows: Figure 11 As shown, the PM31 electrode is effective against NH4 in the biogas slurry. + The adsorption capacity reached 40.07 mg / g, and the desorption capacity reached 36.19 mg / g, for PO4 3- The adsorption capacity reached 53.14 mg / g, and the desorption capacity reached 49.60 mg / g. The test results of the selectivity coefficients of the PM31 electrode for different ions were obtained by referring to... Figure 12 PM31 affects NH4 + and PO4 3- The selective allocation coefficients can be maintained at NH4 + / Na + >3 and PO4 3- / Cl - With a value >18, this electrode material exhibits high capacity and high selectivity. It can selectively and reversibly recover ammonia nitrogen and phosphate from wastewater and sewage simultaneously, demonstrating significant environmental benefits and resource utilization potential.

[0113] Furthermore, to characterize the final chemical state of the PM31 electrode after the CDI process, XPS tests were performed on the blank electrode, the cathode and anode (i.e., the PM31 electrode) in the CDI system. All XPS samples were deactivated after adsorption (±1.2 V, 20 min), allowed to stand at room temperature for 5 min, and then repeatedly rinsed with deionized water until the conductivity stabilized (≤2 uScm). -1 The sample was dried under vacuum at 40 °C for 6 h before XPS analysis. The sample preparation process strictly removed weakly coordinated reversibly adsorbed ions (Cl). - Na + However, it can retain species that form inner sphere coordination or strong hydrogen bonds (such as NH4). + , PO-Mo).

[0114] Reference Figure 13 The XPS spectra of Mo before and after adsorption show that Mo3d in the blank sample is present. 5 / 2 It can be decomposed into Mo 6+ ≈232.8eV, Mo 5+ ≈231.2 eV, Mo 4+ ≈229.3 eV, with areas of approximately 58%, 12%, and 30%, respectively. The cathode shifts overall towards lower BE (with Mo) after adsorption. 5+ The component represents ΔBE≈-0.20eV), and Mo 5+ Mo 4+ The proportion increased (Mo) 5+ From 12%→22%, Mo 4 +The change from 30% to 33% indicates that a reversible reduction (Mo) has occurred. 6+ →Mo 5+ / Mo 4+ The anode recovers from its high valence state after adsorption, and Mo... 6+ The area increased to ~66% and showed a slight positive shift (Mo). 6+ ΔBE≈+0.04 eV), corresponding to re-oxidation. This indicates that the Mo sites undergo a reversible valence state cycle of "reduction (cathode) - re-oxidation (anode)" during charge and discharge, providing an electronic basis for the dual-channel adsorption of nitrogen / phosphorus.

[0115] Reference Figure 14 The XPS spectra of O before and after adsorption show that lattice oxygen ≈ 530.46 eV, vacancy correlation ≈ 531.83 eV, and surface -OH / H₂O ≈ 533.05 eV. The cathode shows a significant negative shift in vacancy O after adsorption (ΔBE ≈ -0.13 eV), indicating that oxygen vacancies capture electrons and participate in Mo adsorption. 6+ →Mo 5+ The area of ​​the anode increases (42%→50%) as it is reduced. After adsorption, the number of vacancy O shifts positively (ΔBE≈+0.10 eV) and the proportion of vacancy O decreases (50%→44%), indicating that some vacancies are "healed" under anodic polarization and phosphate coordination.

[0116] Reference Figure 15 The XPS spectra of N element before and after adsorption show that NH4 appears in the cathode spectrum. + -N characteristic peak (≈402.1 eV), confirming NH4 + They are captured at the cathode stage, and the binding mechanism is mainly hydrogen bonding / dipole interaction, with oxygen vacancies / surface -NH or -OH.

[0117] Reference Figure 16 The XPS spectra and total XPS spectra of P before and after adsorption are shown. A single symmetrical double peak is observed in the anolyte spectrum at 133.5 ± 0.3 eV, P2p. 3 / 2 -P2 p1 / 2 Spin splitting is approximately 0.84 eV, with a relatively narrow peak shape (FWHM ≈ 1.2 eV). This is consistent with the inner globular coordination characteristics of PO-Mo, and no free HPO4 exceeding 134 eV was observed. 2- / PO4 3- acromion. This is because of PO4. 3- A σ-bridge PO-Mo coordination is formed at the anode, which extracts electrons from the Mo-O framework, allowing the Mo valence state to recover to a higher valence and repairing vacancies, thus achieving a closed loop of "reduction" at the cathode stage.

[0118] Reference Figure 17The XPS spectra of sulfur before and after adsorption show the presence of C-SOx (high BE, sulfate / sulfonic acid environment) and CSC (low BE, sulfur-doped carbon / PPy-S) characteristics in the samples. The peak positions of the three groups of samples are basically constant (ΔBE < 0.05 eV), indicating that the sulfur functional groups maintain structural stability during cycling, providing assistance for the conductive framework / polar sites, but do not directly participate in valence state exchange.

[0119] Reference Figure 18 The XPS spectra of C elements before and after adsorption show the presence of sp in the sample. 2 Characteristics of CC / C=C, CN / CS, CO, C=O, and π-π* satellite peaks. (Compared to...) Figure 17 The analytical results for S 2p were consistent, with the peak position remaining almost unchanged before and after cycling (ΔBE < 0.05 eV), indicating that the carbon framework remains structurally stable during electrochemical processes, continuously providing an electron / ion transport network and surface coordination support. For the cathode, NH4... + Occupying oxygen vacancies and triggering "single-electron pseudocapacitive reduction" manifests as Mo3d downshift and Mo 5+ / Mo 4+ Increase, negative shift of O1s-ActiveO, appearance of NH4 in N1s + -N. For the anode, PO4 3- Through PO-Mo inner sphere coordination adsorption, the recovery of Mo's high valence state and vacancy healing are promoted (Mo3d high valence increase, O1s-ActiveO positive shift, P2p=133.5±0.3eV double peak, ΔE≈0.84eV). The two then couple to form "NH4+". + Electronic Gifts - PO4 3- The reversible valence state cycle of "electron backflow" explains the material's simultaneous interaction with NH4 in complex systems. + With PO4 3- High selectivity and durability.

[0120] Furthermore, the results of local density of states (LDOS) analysis of the PM31 electrode were compared with those obtained by referring to... Figures 19-22 ,in, Figure 19 Corresponding to NH4 + , Figure 20 Corresponding to Na + , Figure 21 Corresponding to PO4 3- , Figure 22 Corresponding to Cl - The Bader charge transfer diagram is referenced. Figure 23 and Figure 24 ,in, Figure 23 Corresponding to NH4 + , Figure 24 Corresponding to PO4 3-To gain a deeper understanding of the effect of the PM31 electrode on NH4 + and PO4 3- To investigate the highly selective adsorption mechanism, this application constructed C@MoO3 and C@MoO2 slab models on the α-MoO3(130) and α-MoO2(-101) crystal planes and performed DFT calculations. The adsorption energies of the main ions on the C@MoO3(130) / C@MoO2(-101) models are shown in Table 3 below.

[0121] Table 3:

[0122]

[0123] For PO4 3- Using deprotonated PO4 3- As an adsorbent, it reflects the deprotonation that may occur during surface coordination, thus more closely resembling the actual state of the experimental interface. The most significant finding is the adsorption energy ranking: PO4 3- <NH4 + ≤Na + <Cl - Taking the MoO3 surface as an example, the values ​​are -7.81, -4.58, -0.65, and +2.02 eV; the trend is consistent for the MoO2 surface. This reflects that the target ions have a thermodynamically preferential occupancy advantage at the MoOx interface, while the binding force of coexisting monovalent ions is significantly weaker. Furthermore, NH4+... + With PO4 3- The adsorption energy difference between the two crystal planes is less than 0.5 eV, which verifies the importance of the joint participation of multiple crystal planes, rather than the exclusive effect of a single crystal plane on a single ion.

[0124] Electronic structure analysis (including differential charge density and LDOS) further reveals that: NH4 + Adsorption is accompanied by an electron transfer of approximately 0.85 e⁻ from N₂p to Mo₄d, resulting in localized Mo… 6+ Restore to Mo 5+ ;PO4 3- Adsorption triggers σ-bridged PO-Mo coordination, simultaneously inducing Mo4d→O2p at approximately 1.3-1.4 e⁻. - Electron migration, a process originating from MoO x Electrons are extracted from the framework, causing the oxidation state of Mo to shift to a higher Mo value. 6+ Movement. This electron transfer pathway is similar to the "Mo under cathode conditions" observed in XPS. 5+ Increased / Anodic conditions Mo 6+ The high degree of matching between the valence state shifts of "recovery" indicates that thermodynamic preference and electron transfer mechanisms jointly drive the process at the biphase MoOx interface. Meanwhile, "NH4" + Electronic gifts and PO43- "Electron backflow" in MoO x A reversible valence cycle is formed within the framework, ensuring that NH4... + High-speed and high-selectivity adsorption, while avoiding MoO x Structural degradation caused by price decline.

[0125] In summary, the interfacial role of PM31 can be categorized into a "polycrystalline facet-dual-path driven" model: α-MoO3 and α-MoO2 each contribute different valence states and electronic energy level structures, working together to form an interface with NH4+. + and PO4 3- The two channels share the Mo4d electron pool and are reversibly adsorbed via Mo4d electrons. 6+ / Mo 5+ / Mo 4+ The cyclic process achieves simultaneous optimization of thermodynamics and kinetics. This "thermodynamic preferential site occupancy + electron transfer self-healing" mechanism, together with the aforementioned experimental results, forms a complete system, providing a solid theoretical foundation for the further design of highly selective nitrogen-phosphorus electroadsorption electrodes.

[0126] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the patent protection scope of this application.

Claims

1. A method for preparing a molybdenum oxide heterojunction composite electrode, characterized in that, The method for preparing the molybdenum oxide heterojunction composite electrode includes the following steps: A conductive polymer precursor is mixed and ground with a molybdenum source to obtain a mixture, wherein the molybdenum source generates α-MoO2 and α-MoO3 after pyrolysis treatment, and the conductive polymer precursor includes at least one of PPy-DBSA, PANI-DBSA and PPy-PSS, and the mass ratio between the conductive polymer precursor and the molybdenum source is (1~4):(4~1). The mixture was subjected to pyrolysis under an inert atmosphere to obtain composite powder. The composite powder, binder, and solvent are mixed to obtain a slurry; The slurry is loaded onto a current collector to prepare a molybdenum oxide heterostructure composite electrode, wherein the molybdenum oxide heterostructure composite electrode is used in a capacitive deionization system.

2. The method for preparing a molybdenum oxide heterojunction composite electrode as described in claim 1, characterized in that, The molybdenum source includes: (NH4)2MoO4, (NH4)6Mo7O 24 At least one of MoCl5 and (NH4)2MoS4.

3. The method for preparing a molybdenum oxide heterojunction composite electrode as described in claim 1, characterized in that, The loading of the molybdenum oxide heterojunction composite electrode is 2~6 mg / cm³. 2 .

4. The method for preparing a molybdenum oxide heterojunction composite electrode as described in claim 1, characterized in that, The pyrolysis treatment includes: heating to 500-700 ℃ at a heating rate of 5-15 ℃ / min, holding at that temperature for 2-6 h, and then cooling to room temperature.

5. The method for preparing a molybdenum oxide heterointerface composite electrode as described in claim 1, characterized in that, The adhesive includes at least one of PVDF, PTFE and CMC / SBR; And / or, the solvent includes at least one of NMP, DMF, and DMSO; And / or, the current collector includes at least one of graphite paper, carbon cloth, and Ti mesh.

6. The method for preparing a molybdenum oxide heterointerface composite electrode as described in claim 1, characterized in that, By mass ratio, the composite powder: conductive agent: binder in the slurry is (70~90):(0~15):(5~15).

7. The method for preparing a molybdenum oxide heterointerface composite electrode as described in claim 1, characterized in that, The step of loading the slurry onto the current collector to prepare a molybdenum oxide heterojunction composite electrode includes: Apply the slurry to the current collector with a coating thickness of 50~150 μm; Molybdenum oxide heterostructure composite electrode was prepared by vacuum drying at 40-80 °C for 6-12 h.

8. A molybdenum oxide heterojunction composite electrode, characterized in that, The molybdenum oxide heterostructure composite electrode is prepared by the method described in any one of claims 1 to 7.

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