Double-heterojunction electrode photocatalytic fuel cell system and method for synthesizing ammonia

Abstract

The invention belongs to but is not limited to the technical field of new energy batteries, and discloses a photocatalytic fuel cell system for pollutant treatment based on a heterojunction structure and a preparation method of the photocatalytic fuel cell system, based on a PFC system, an antibiotic pollutant is anodized, and a nitrate pollutant is reduced by a cathode; the energy range difference between the anode heterojunction Fermi energy level and the cathode heterojunction Fermi energy level drives system electrons to transfer and output electric energy; based on the reaction principle of PFC, nitrate existing in the wastewater is used as a cathode electron acceptor to synergistically realize reduction of nitrate pollutants to synthesize ammonia and oxidation of organic pollutants, so that the two pollutants of an anode and a cathode are synchronously removed.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the field of new energy battery technology and water pollution control technology, and in particular relates to a photocatalytic fuel cell system and method for the coordinated treatment of organic-inorganic pollutants and simultaneous synthesis of ammonia. Background Art

[0002] The photocatalytic fuel cell system (PFC) based on the heterojunction structure can convert the chemical energy contained in solar energy and organic pollutants into green electrical energy and remove pollutants simultaneously. In a typical PFC, the Fermi level of the photoanode is higher than the Fermi level of the photocathode. The internal bias formed drives the photoanode electrons to combine with the photocathode holes through the external circuit, thereby releasing the photoanode holes and photocathode electrons; acting on the photocatalytic oxidation (anode) and reduction processes (cathode), respectively, which can effectively reduce the recombination probability of the photogenerated holes and electrons of the two electrodes. That is, the Fermi level difference between the two photoelectrodes drives the directional transmission of photogenerated electrons, enabling the photoanode to provide electrons for the cathode catalytic reaction while oxidizing the difficult-to-degrade organic pollutants, driving the cathode reaction to reduce inorganic pollutants (such as nitrates). Using nitrate (NO3 - ) Synthesis of high value-added ammonia (NH3) provides an effective way for sustainable ammonia synthesis and nitrate wastewater treatment. The existing technical problems of photocatalytic fuel cell systems in pollutant treatment mainly include the following aspects:

[0003] 1. High recombination rate of photogenerated carriers: Although PFC uses the Fermi level difference of dual photoelectrodes to drive the separation of photogenerated electrons and holes, the recombination problem of photogenerated electrons and holes still exists. The high recombination rate reduces the utilization efficiency of photogenerated carriers, thereby limiting the efficiency of photocatalytic reactions and resulting in insufficient pollutant removal capacity.

[0004] 2. Insufficient activity and stability of catalytic materials: Although the photocatalytic materials used in PFC (such as TiO2, ZnO, etc.) have certain photocatalytic activity, their activity is limited under visible light, and long-term use will cause the activity to decrease due to photocorrosion or other environmental factors. This will affect the overall efficiency and service life of the system.

[0005] 3. Limited light absorption range: Most common photocatalytic materials mainly absorb ultraviolet light (such as TiO2), and the proportion of ultraviolet light in sunlight is very low (about 5%). This means that the utilization efficiency of solar energy is low and the activity of photocatalytic reactions under visible light is limited.

[0006] 4. Low electron transfer efficiency: Although the dual photoelectrode design can drive the directional transfer of photogenerated electrons, the efficiency of electron transfer is low due to the selection of electrode materials or the mismatch of the heterojunction interface, which in turn affects the photoelectric conversion efficiency and pollutant removal efficiency of the battery.

[0007] 5. Limited ability to treat complex pollutants: Existing technologies are limited in their effectiveness in treating multiple pollutants (e.g., treating both organic and inorganic pollutants, such as nitrates). The redox reaction rates of some pollutants are different, which leads to an imbalance in the efficiency of the system in the treatment of multiple pollutants, making it difficult to achieve simultaneous and efficient removal.

[0008] 6. Insufficient optimization of Fermi level difference design: In the existing technology, although the Fermi level difference of the dual photoelectrode can promote the directional transmission of photogenerated electrons, its design still needs to be optimized to better match the treatment requirements of different pollutants, thereby improving the overall efficiency.

[0009] To solve the above technical problems, the application potential of the PFC system in the treatment of multiple pollutants and simultaneous synthesis of ammonia can be realized by regulating the photoelectrode heterojunction structure, especially improving its photoelectric conversion efficiency and pollutant removal effect. Summary of the invention

[0010] In view of the problems existing in the prior art, the present invention provides a method for constructing a photocatalytic fuel cell system for the coordinated treatment of organic-inorganic pollutants and the simultaneous synthesis of ammonia.

[0011] The present invention is implemented as follows: a method for constructing a photocatalytic fuel cell system for the coordinated treatment of organic-inorganic pollutants and the simultaneous synthesis of ammonia. The system uses a Ag2S / ZnO nanoarray heterojunction structure instead of ZnO nanoparticles as the anode material:

[0012] The anode is composed of a Ag2S / ZnO heterojunction structure, in which ZnO is prepared on a conductive substrate by a sol-gel method, and then a layer of silver sulfide (Ag2S) is deposited on its surface to form a heterojunction structure with good photocatalytic activity to improve the photoelectric conversion efficiency of the anode; the cathode material uses a MXene-based material and a spinel ferrite to construct a heterojunction structure, and the spinel ferrite prepared by a hydrothermal method is composited with the MXene-based material to form a photocathode;

[0013] The reaction solution in the anode chamber is a solution of refractory organic pollutants (antibiotics, endocrine disruptors, perfluorinated compounds, etc.), and the cathode chamber is a nitrate solution. The cathode and anode chambers are separated by a Nafion membrane; the external loop uses a silver-plated copper wire to connect the load.

[0014] Furthermore, the fuel cell is constructed based on a PFC (double heterojunction electrode photocatalytic fuel cell for simultaneous synthesis of ammonia by treating organic-inorganic pollutants) system, comprising a heterojunction double photoelectrode, an external circuit, an electrolyte, a fuel and an ion exchange membrane, wherein:

[0015] The binary photoanode adopts a nano-array Ag2S / ZnO heterojunction structure.

[0016] The arrangement and surface modification of ZnO nanoarrays constructs a photoanode with a high specific surface area and enhanced light absorption capacity, which significantly improves the catalytic oxidation efficiency of the photoanode and optimizes the separation and migration process of electron-hole pairs at the nanoscale, thereby greatly improving the photoelectric conversion efficiency;

[0017] The binary photocathode is composed of a metal Ti3C2 (MXene) and spinel ferrite heterojunction structure. A variety of bimetallic spinel ferrites are prepared by introducing different precursor metals. The high conductivity of Ti3C2 (MXene) and the strong photocatalytic reduction ability of spinel ferrite are combined to form a two-component co-catalyst. This heterojunction structure optimizes the reduction reaction path of nitrates by regulating the electronic band structure and surface activity of the photocathode, and improves the activity and selectivity of nitrate reduction to synthesize ammonia.

[0018] The connection between the anode and the cathode has been precisely optimized to ensure efficient transmission of photogenerated carriers. By adjusting the conduction band and valence band of the binary heterojunction anode, the fuel cell can achieve efficient redox reaction without external voltage application, effectively improving the overall energy utilization and electrochemical stability of the device.

[0019] Furthermore, the electrolyte of the fuel cell is composed of organic (antibiotics, dyes, etc.) and inorganic (nitrate) wastewater, respectively, and with the synergistic effect of the multifunctional catalyst, it achieves efficient simultaneous treatment of different types of pollutants and synthesis of ammonia;

[0020] A xenon lamp is used as a simulated light source, which can provide high-intensity light irradiation close to the solar spectrum, enhance the light absorption performance of the photoanode, and ensure the reliability and practicality of laboratory test results by simulating natural lighting conditions;

[0021] The modular design of the device structure allows the anode, cathode and electrolyte to be flexibly adjusted and replaced according to different application requirements, further enhancing the applicability of heterojunction-based photocatalytic fuel cell systems for pollutant treatment.

[0022] The design of the multilayer ion exchange membrane optimizes the selective ion transport, reduces ion cross-contamination in the electrolyte, and reduces membrane impedance through innovative structural design, further improving the energy conversion efficiency and electrochemical performance of the battery, showing excellent stability and long life characteristics.

[0023] Furthermore, based on the reaction principle of PFC, the nitrate present in the wastewater is used as a cathode electron acceptor to synergistically achieve the reduction of nitrate pollutants to synthesize ammonia and the oxidation of organic pollutants, so that both anode and cathode pollutants can be removed simultaneously.

[0024] The present invention also provides a method for treating organic pollutants and simultaneously synthesizing ammonia, comprising the following steps:

[0025] (1) adding a solution containing organic pollutants into the anode chamber, wherein the organic pollutants include antibiotics, endocrine disruptors or perfluorinated compounds;

[0026] (2) adding nitrate solution into the cathode chamber and separating the cathode and anode chambers by a Nafion membrane;

[0027] (3) Under the irradiation of light source, the Ag2S / ZnO heterojunction anode is used to photocatalytically oxidize and degrade organic pollutants;

[0028] (4) using MXene / spinel ferrite heterojunction cathode to generate ammonia during nitrate reduction;

[0029] (5) Connect the anode and cathode through an external circuit and record the current and voltage to evaluate the reaction efficiency.

[0030] Further, the preparation steps of the anode include:

[0031] (1) Preparation of ZnO nanoarrays on conductive substrates by sol-gel method;

[0032] (2) depositing a layer of silver sulfide (Ag2S) on the surface of the ZnO nanoarray by ion exchange to form an Ag2S / ZnO heterojunction structure;

[0033] (3) Drying and annealing the heterojunction structure to improve the photoelectric conversion efficiency.

[0034] Further, the preparation steps of the cathode include:

[0035] (1) Depositing MXene material on a substrate by a hydrothermal method to form a conductive layer;

[0036] (2) Preparation of spinel ferrite (such as CoFe2O4 or NiFe2O4) nanostructures by hydrothermal method;

[0037] (3) Composite spinel ferrite and MXene to form a heterojunction photocathode;

[0038] (4) Drying and annealing to enhance structural stability and catalytic performance.

[0039] Furthermore, the operating conditions include:

[0040] (1) The anode chamber solution is a 10-50 ppm organic pollutant solution, and the cathode chamber solution is a 0.5-1 M nitrate solution;

[0041] (2) Irradiating the system by simulating sunlight or visible light (wavelength λ>420nm);

[0042] (3) Loading a resistor in the external circuit or connecting a potential controller to maintain a constant current density and monitor the photocurrent and reaction efficiency;

[0043] (4) Record the ammonia production in the cathode chamber and the degradation rate of organic pollutants in the anode chamber.

[0044] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0045] First, the present invention has a simple structure and is easy to operate, and can convert chemical energy into electrical energy while degrading various pollutants.

[0046] The present invention is based on the reaction principle of PFC. If there is nitrate in the wastewater, it can be used as a cathode electron acceptor to synergistically achieve the reduction of nitrate pollutants to synthesize ammonia and the oxidation of organic pollutants, so that both anode and cathode pollutants are removed simultaneously. Develop photocatalytic cathode materials with excellent adsorption performance and selective catalytic reduction activity. Based on the construction of a new functional cathode PFC, the efficiency of nitrate synergistic removal will be improved and the energy consumption level will be reduced. It has important scientific value and application value for the treatment and resource utilization of wastewater such as nitrate and difficult-to-degrade organic pollutants.

[0047] Second, the technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0048] The implementation of this project will provide important scientific information and theoretical basis for the design of power-generating reactors and the development of electrode materials based on the control of complex pollutants, deepen the understanding of the working principles of synergistic treatment of pollutants, and obtain new knowledge in the intersection of environmental chemistry and nanocatalytic chemistry.

[0049] Thirdly, the technical solution of the present invention solves the technical problems of the existing photocatalytic fuel cell system for pollutant treatment in terms of catalytic efficiency, material stability and pollutant treatment effect through innovative material preparation and combination methods, and has achieved significant technical progress in the following aspects:

[0050] 1) Improved photocatalytic efficiency: By using Ag2S / ZnO as anode material and combining Mxene / CoFe2O4 composite material as cathode, the present invention significantly enhances the overall catalytic performance of the photocatalytic fuel cell system. Mxene material has excellent conductivity and large specific surface area, which can effectively improve the electron conduction efficiency, while CoFe2O4, as a magnetic oxide, has good photocatalytic activity and selectivity, which improves the performance of synthetic ammonia.

[0051] 2) Enhanced material stability and durability: The present invention synthesizes highly active Ag2S / ZnO and Mxene / CoFe2O4 composite materials at a relatively low temperature, thereby avoiding the damage to the material structure caused by high-temperature calcination, thereby ensuring the stability of the material and its durability during long-term use. Compared with traditional photocatalytic materials, the composite materials in the present invention can still maintain good catalytic activity after multiple cycles of use, solving the problem of easy deactivation of materials in the prior art.

[0052] 3) Achieved efficient pollutant treatment: The present invention uses antibiotic wastewater and nitrate wastewater as electrolytes for the anode and cathode, respectively, and uses a photocatalytic fuel cell system based on a heterojunction structure for pollutant treatment to achieve simultaneous degradation of the two types of pollutants. Ag2S / ZnO has a good degradation effect on antibiotic pollutants, while the Mxene / CoFe2O4 binary heterojunction material can effectively reduce nitrate pollutants to efficiently and selectively synthesize ammonia, successfully solving the problem of low efficiency in single pollutant treatment in the prior art and achieving multifunctional wastewater treatment.

[0053] 4) Improved system applicability and operability: By optimizing the material preparation method and the structural design of the heterojunction-based photocatalytic fuel cell system for pollutant treatment, the present invention simplifies the operation steps and reduces the complexity of equipment manufacturing and maintenance, making the technology have a wider application prospect in the field of industrial wastewater treatment. At the same time, since the material preparation process is environmentally friendly and low-cost, the present invention has good economic and social benefits.

[0054] In general, the present invention has achieved remarkable technical progress in improving photocatalytic efficiency, enhancing material stability, achieving efficient treatment of multiple pollutants, and improving system applicability, and is expected to be widely used in fields such as environmental protection and industrial wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic structural diagram of a double heterojunction electrode photocatalytic fuel cell system for simultaneous synthesis of ammonia by treating organic-inorganic pollutants provided by an embodiment of the present invention;

[0056] Figure 2This is the antibiotic degradation diagram a and nitrate reduction diagram b for treating organic-inorganic pollutants provided by the embodiments of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0058] The present invention proposes a PFC (double heterojunction electrode photocatalytic fuel cell system for simultaneous synthesis of ammonia for organic-inorganic pollutant treatment) system, which consists of two photoelectrodes, an external circuit, an electrolyte, a fuel, and an ion exchange membrane. Through the selection and optimization of different electrode materials, the present invention can flexibly determine the applicable chemical reagents and materials according to the needs of the application scenario, thereby achieving a multifunctional pollutant treatment effect. The photoanode of the heterojunction-based photocatalytic fuel cell system for pollutant treatment is specifically used to oxidize difficult-to-degrade organic pollutants such as antibiotics, while the photocathode is used to reduce nitrate pollutants.

[0059] First, the photoanode adopts a nano-array Ag2S / ZnO heterojunction structure. The ZnO nano-array has the advantages of high specific surface area and enhanced light absorption capacity, which can significantly improve the photoelectric performance of the photoanode. By constructing a heterojunction on the ZnO surface, this design effectively improves the catalytic ability of the anode in the process of oxidizing antibiotic molecules, thereby significantly improving the photoelectric conversion efficiency, making the photocatalytic fuel cell system based on the heterojunction structure for pollutant treatment show higher efficiency in practical applications.

[0060] Secondly, the photocathode uses a heterojunction constructed of metal Ti3C2 (MXene) and spinel ferrite. Ti3C2 (MXene) is an ideal photocathode material due to its excellent conductivity and catalytic properties, while spinel ferrite forms a structure with different bimetallic compositions by changing the type of precursor metal. This composite material is precisely designed to form a two-component co-catalyst, which significantly enhances the electron transfer ability, catalytic activity and selectivity of the cathode.

[0061] Through the precise design and application of the two-component co-catalyst, the composite ratio of Ti3C2 and spinel ferrite has been optimized, so that the photocathode exhibits stronger catalytic activity in the process of reducing nitrate pollutants. This design not only enhances the reduction ability of the photocathode, but also effectively reduces the overall resistance of the heterojunction-based photocatalytic fuel cell system used for pollutant treatment, thereby improving the energy conversion efficiency of the device and increasing the practicality and stability of the device.

[0062] In addition, the present invention uses a xenon lamp as a simulated light source. This light source can provide strong light irradiation close to the solar spectrum, significantly enhancing the light absorption efficiency of the photoanode. At the same time, the use of a xenon lamp enables the PFC device to simulate the working state in the actual environment under laboratory conditions, thereby ensuring the reliability and repeatability of the test results, which is convenient for subsequent research and application promotion.

[0063] In terms of the connection design between the anode and the cathode, the present invention optimizes the electron transfer between the two electrodes to make it more efficient. By adjusting the conduction band and valence band of the anode, the open circuit voltage of the device is further optimized, so that the photocatalytic fuel cell system based on the heterojunction structure for pollutant treatment can effectively carry out redox reactions without external voltage. This design greatly improves the overall working efficiency of the device and simplifies the operation process.

[0064] Another innovation of the present invention is the simultaneous synthesis of ammonia during pollutant treatment. The present invention uses wastewater containing nitrates and antibiotics as electrolytes, and achieves simultaneous synthesis of ammonia by selective regulation of cathode materials. This design demonstrates the broad application prospects of heterojunction-based photocatalytic fuel cell systems for pollutant treatment, and provides an efficient and multifunctional solution for environmental pollution control and green production capacity.

[0065] The photocatalytic fuel cell system based on heterojunction structure for pollutant treatment of the present invention has achieved significant improvements in pollutant treatment efficiency, photoelectric conversion performance, material stability and overall energy utilization of the device. This innovative design not only improves the practicality and stability of the equipment, but also makes the photocatalytic fuel cell system based on heterojunction structure for pollutant treatment have important market value and development prospects in industrial applications.

[0066] Example 1: Treatment of antibiotic-containing wastewater and synthesis of ammonia

[0067] 1. Anode preparation:

[0068] Conductive glass (FTO) was used as the substrate, and ZnO nanoarrays were deposited on the substrate surface by a sol-gel method.

[0069] An Ag2S layer is generated on the ZnO surface through a sulfurization reaction, forming an Ag2S / ZnO heterojunction structure.

[0070] After drying, annealing is performed to enhance structural stability.

[0071] 2. Cathode preparation:

[0072] MXene nanosheets were deposited by hydrothermal method on a conductive substrate to form a good conductive layer.

[0073] Spinel ferrite (such as CoFe2O4) is synthesized by a hydrothermal method and composited with a MXene substrate to form a MXene / spinel ferrite heterojunction.

[0074] 3. Operating conditions:

[0075] Wastewater containing 10 ppm of antibiotics was added to the anode chamber, and 1 M nitrate solution was added to the cathode chamber.

[0076] A Nafion membrane was used to separate the two chambers, and visible light radiation (λ>420nm) was introduced into the photocatalytic fuel cell system.

[0077] A 10Ω resistor was loaded into the external circuit, and the photocurrent and voltage were recorded.

[0078] 4. Results:

[0079] The degradation rate of organic matter in antibiotic wastewater reaches 92%.

[0080] The nitrate removal rate in the cathode chamber reached 92%, and the synthetic ammonia selectivity was 87%.

[0081] Example 2: Treatment of endocrine disruptor wastewater and synthesis of ammonia

[0082] 1. Anode preparation:

[0083] The ZnO nanoarrays were prepared by sol-gel method using titanium mesh as conductive substrate.

[0084] The Ag2S layer was deposited on the ZnO surface by liquid phase deposition to form a highly efficient photocatalytic anode.

[0085] Dry and anneal to enhance structural properties.

[0086] 2. Cathode preparation:

[0087] MXene material was deposited on the carbon fiber cloth substrate by hydrothermal method.

[0088] Spinel ferrite (such as NiFe2O4) is synthesized by a hydrothermal method and composited with a MXene substrate to form a heterojunction photocathode.

[0089] 3. Operating conditions:

[0090] Wastewater containing 50 ppm of endocrine disruptor bisphenol A was added to the anode chamber, and 0.5 M nitrate solution was added to the cathode chamber.

[0091] The two chambers were separated by a Nafion membrane and the system was operated under a solar simulator (100 mW / cm 2 ).

[0092] The external circuit is connected to a potential controller to maintain a constant current density.

[0093] 4. Results:

[0094] The degradation rate of bisphenol A reached 90% and the mineralization rate reached 88%.

[0095] The nitrate removal rate in the cathode chamber is 88%, and the selectivity of synthetic ammonia is 85%. The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A double heterojunction electrode photocatalytic fuel cell system for simultaneous synthesis of ammonia by treating organic and inorganic pollutants, characterized in that: The system uses Ag2S / ZnO nanoarray heterojunction structure instead of ZnO nanoparticles as anode material: The anode is composed of a Ag2S / ZnO heterojunction structure, in which ZnO is prepared on a conductive substrate by a sol-gel method, and then a layer of silver sulfide (Ag2S) is deposited on its surface to form a heterojunction structure with good photocatalytic activity to improve the photoelectric conversion efficiency of the anode; the cathode material uses a MXene-based material and spinel ferrite to construct a heterojunction structure, and the carbon material is deposited on the substrate by a hydrothermal method, and then composited with the spinel ferrite prepared by the hydrothermal method to form a photocathode; The reaction solution in the anode chamber is a solution of refractory organic pollutants (antibiotics, endocrine disruptors, perfluorinated compounds, etc.), and the cathode chamber is a nitrate solution. The cathode and anode chambers are separated by a Nafion membrane; the external loop uses a silver-plated copper wire to connect the load.

2. The double heterojunction electrode photocatalytic fuel cell system for simultaneous synthesis of ammonia by treating organic and inorganic pollutants as claimed in claim 1, characterized in that: The fuel cell is constructed based on a PFC (double heterojunction electrode photocatalytic fuel cell for simultaneous synthesis of ammonia by treating organic-inorganic pollutants) system, comprising a heterojunction double photoelectrode, an external circuit, an electrolyte, a fuel and an ion exchange membrane, wherein: The binary photoanode adopts a nano-array ZnO heterojunction structure. By precisely controlling the arrangement and surface modification of the ZnO nano-array, a photoanode with a high specific surface area and enhanced light absorption capacity is constructed, which significantly improves the catalytic oxidation efficiency of the photoanode and optimizes the separation and migration process of electron-hole pairs at the nanoscale, thereby greatly improving the photoelectric conversion efficiency. The binary photocathode is composed of a metal Ti3C2 (MXene) and spinel ferrite heterojunction structure. A variety of bimetallic spinel ferrites are prepared by introducing different precursor metals. The high conductivity of Ti3C2 (MXene) and the strong photocatalytic reduction ability of spinel ferrite are combined to form a two-component co-catalyst. This heterojunction structure optimizes the reduction reaction path of nitrates by regulating the electronic band structure and surface activity of the photocathode, and improves the activity and selectivity of nitrate reduction to synthesize ammonia. The connection between the anode and the cathode has been precisely optimized to ensure efficient transmission of photogenerated carriers. By adjusting the conduction band and valence band of the binary heterojunction anode, the fuel cell can achieve efficient redox reaction without external voltage application, effectively improving the overall energy utilization and electrochemical stability of the device.

3. The double heterojunction electrode photocatalytic fuel cell system for simultaneous synthesis of ammonia by treating organic and inorganic pollutants as claimed in claim 1, characterized in that: The electrolyte of the fuel cell is composed of nitrate and antibiotic wastewater, wherein the nitrate concentration is 0.5-1M and the antibiotic solution concentration is 10-50ppm; The light source is a xenon lamp with a power between 150W and 500W, and is focused to the anode surface through a lens system for photocatalytic reaction; The device structure of the fuel cell adopts a modular design. The anode module, cathode module and electrolyte module can be independently disassembled and replaced. The anode and cathode materials can be selected according to different reaction requirements and are made of photocatalytic semiconductor materials or conductive materials. The electrolyte module can accommodate electrolytes of different volumes and compositions and is suitable for different experimental conditions. The ion exchange membrane is a multilayer structure, the outermost layer is a proton exchange membrane (Nafion membrane), the inner layer is an anion exchange membrane, the membrane material is sulfonated polyetheretherketone (SPEEK) or perfluorosulfonic acid resin, the membrane thickness is 50μm-200μm, it is prepared by solution casting or hot pressing, and the membrane surface is hydrophilic to improve ion conductivity; The shell material of the device is made of highly corrosion-resistant polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) to ensure chemical stability during long-term use, and all internal connections use silver wires or silver-plated copper wires to reduce resistance loss and enhance conductivity.

4. The double heterojunction electrode photocatalytic fuel cell system for simultaneous synthesis of ammonia by treating organic and inorganic pollutants as claimed in claim 1, characterized in that: Based on the reaction principle of PFC, the nitrate in the wastewater is used as the cathode electron acceptor to synergistically realize the reduction of nitrate pollutants to synthesize ammonia and the oxidation of organic pollutants, so that both anode and cathode pollutants can be removed simultaneously.

5. A method for treating organic pollutants and simultaneously synthesizing ammonia, characterized in that: The following steps are involved: (1) adding a solution containing organic pollutants into the anode chamber, wherein the organic pollutants include antibiotics, endocrine disruptors or perfluorinated compounds; (2) adding nitrate solution into the cathode chamber and separating the cathode and anode chambers by a Nafion membrane; (3) Under the irradiation of light source, the Ag2S / ZnO heterojunction anode is used to photocatalytically oxidize and degrade organic pollutants; (4) using MXene / spinel ferrite heterojunction cathode to generate ammonia during nitrate reduction; (5) Connect the anode and cathode through an external circuit and record the current and voltage to evaluate the reaction efficiency.

6. The method according to claim 5, characterized in that The steps of preparing the anode include: (1) Preparation of ZnO nanoarrays on conductive substrates by sol-gel method; (2) depositing a layer of silver sulfide (Ag2S) on the surface of the ZnO nanoarray to form an Ag2S / ZnO heterojunction structure; (3) Drying and annealing the heterojunction structure to improve the photoelectric conversion efficiency.

7. The method according to claim 5, characterized in that The preparation steps of the cathode include: (1) Depositing MXene material on a substrate by a hydrothermal method to form a conductive layer; (2) Preparation of spinel ferrite nanostructures by hydrothermal method; (3) Composite spinel ferrite and MXene to form a heterojunction photocathode; (4) Drying and annealing to enhance structural stability and catalytic performance.

8. The method according to claim 5, characterized in that The operating conditions include: (1) The anode chamber solution is a 10-50 ppm organic pollutant solution, and the cathode chamber solution is a 0.5-1 M nitrate solution; (2) irradiating the system by simulating sunlight or visible light; (3) Loading a resistor in the external circuit or connecting a potential controller to maintain a constant current density and monitor the photocurrent and reaction efficiency; (4) Record the ammonia production in the cathode chamber and the degradation rate of organic pollutants in the anode chamber.

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