Biheterojunction electrode photocatalytic fuel cell system and method for synthesis of ammonia

Abstract

The application belongs to but is not limited to the technical field of new energy batteries, and discloses a photocatalytic fuel cell system based on a heterojunction structure for pollutant treatment and a preparation method thereof. Based on a PFC system, antibiotic pollutants are oxidized at an anode, and nitrate pollutants are reduced at a cathode. An energy difference between Fermi energy levels of an anode heterojunction and Fermi energy levels of a cathode heterojunction drives system electron transfer to output electric energy. Based on the reaction principle of the PFC, nitrate existing in wastewater is used as a cathode electron acceptor, and the reduction of nitrate pollutants to synthesize ammonia and the oxidation of organic pollutants are realized in cooperation, so that the two kinds of pollutants at the anode and the cathode are synchronously removed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new energy battery technology and water pollution control technology, and particularly relates to a photocatalytic fuel cell system and method for simultaneous synthesis of ammonia by treating organic-inorganic pollutants. BACKGROUND

[0002] The photocatalytic fuel cell system (PFC) based on heterojunction structure can convert solar energy and chemical energy contained in organic pollutants into green electricity, and simultaneously remove pollutants. In a typical PFC, the Fermi level of the photoanode is higher than that of the photocathode, and the internal bias formed drives the photoanode electrons to combine with the photocathode holes through an external circuit, and then releases the photoanode holes and the photocathode electrons; which respectively act on the photocatalytic oxidation (anode) and reduction process (cathode), can effectively reduce the recombination probability of photo-generated holes and electrons. That is, the Fermi level difference between the two photoelectrodes drives the directional transport of photo-generated electrons, which enables the photoanode to oxidize refractory organic pollutants while providing electrons for the cathode catalytic reaction, driving the cathode reaction to reduce inorganic pollutants (such as nitrate). The synthesis of high-value-added ammonia (NH3) from nitrate (NO3 - ) provides an effective way for sustainable ammonia synthesis and nitrate wastewater treatment. The existing technical problems of the photocatalytic fuel cell system in pollutant treatment mainly include the following aspects:

[0003] 1. High recombination rate of photo-generated carriers: Although PFC utilizes the Fermi level difference between the two photoelectrodes to drive the separation of photo-generated electrons and holes, the problem of recombination of photo-generated electrons and holes still exists. High recombination rate reduces the utilization efficiency of photo-generated carriers, thereby limiting the efficiency of photocatalytic reaction, resulting in insufficient removal of pollutants.

[0004] 2. Insufficient activity and stability of catalytic materials: The photocatalytic materials (such as TiO2, ZnO, etc.) used in PFC have certain photocatalytic activity, but their activity is limited under visible light, and long-term use will cause activity decline due to photo-corrosion 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 reaction under visible light is limited.

[0006] 4. Low electron transport efficiency: Although the design of double photoelectrodes can drive the directional transport of photo-generated electrons, due to the selection of electrode materials or mismatch of heterojunction interface, the efficiency of electron transport is low, which further affects the photoelectric conversion efficiency of the cell and the removal efficiency of pollutants.

[0007] 5. Limited treatment capacity for complex pollutants: Existing technologies have limited effectiveness in treating multiple pollutants simultaneously (e.g., both organic and inorganic pollutants such as nitrate). The different redox reaction rates of some pollutants lead to an imbalance in system efficiency during the treatment of multiple pollutants, making it difficult to achieve simultaneous high-efficiency removal.

[0008] 6. Insufficient optimization of Fermi level difference design: Although the Fermi level difference of the dual photoelectrode in existing technologies can promote the directional transport of photo-generated electrons, its design still needs to be optimized to better match the treatment needs of different pollutants, thereby improving overall efficiency.

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

[0010] To address the problems of existing technologies, the present application provides a method for constructing a photo-catalytic fuel cell system for simultaneous ammonia synthesis and co-treatment of organic and inorganic pollutants.

[0011] The present application is achieved by a method for constructing a photo-catalytic fuel cell system for simultaneous ammonia synthesis and co-treatment of organic and inorganic pollutants, which uses Ag2S / ZnO nanometer array heterojunction structure instead of ZnO nanoparticles as anode material:

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

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

[0014] Further, the fuel cell is based on a PFC (dual heterojunction electrode photo-catalytic fuel cell for simultaneous ammonia synthesis and organic-inorganic pollutant treatment) system construction, which includes a heterojunction dual 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, and the Ag2S /

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

[0017] The binary photoanode is composed of a metal Ti3C2 (MXene) and a spinel ferrite heterojunction structure. By introducing different precursor metals, a variety of double-metal spinel ferrites are prepared. Combined with the high conductivity of Ti3C2 (MXene) and the strong photocatalytic reduction ability of spinel ferrite, a two-component cocatalyst is formed. This heterojunction structure optimizes the electron band structure and surface activity of the photoanode, optimizes the reduction reaction path of nitrate, and improves the activity and selectivity of nitrate reduction to synthesize ammonia;

[0018] The connection between the anode and the cathode is precisely optimized to ensure efficient transport of photo-generated carriers. By adjusting the conduction band and valence band of the binary heterojunction anode, the fuel cell can achieve efficient oxidation-reduction reaction without external voltage application, effectively improving the overall energy utilization and electrochemical stability of the device.

[0019] Further, the electrolyte of the fuel cell is composed of organic (antibiotics, dyes, etc.) and inorganic (nitrate) wastewater, respectively. With the synergistic effect of multifunctional catalysts, simultaneous efficient treatment of different types of pollutants and synthesis of ammonia are achieved;

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

[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 the heterojunction structure-based photocatalytic fuel cell system for pollutant treatment;

[0022] The design of multi-layer ion exchange membrane optimizes ion selective 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, exhibiting excellent stability and long life characteristics.

[0023] Further, based on the reaction principle of PFC, the nitrate existing in the wastewater is used as a cathode electron acceptor, and the reduction of nitrate pollutants and the oxidation of organic pollutants are realized simultaneously, so that the anode and the cathode can remove the two kinds of pollutants synchronously.

[0024] The application 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 a nitrate solution into the cathode chamber, and separating the cathode chamber and the anode chamber by a Nafion membrane;

[0027] (3) under the irradiation of a light source, using the Ag2S / ZnO heterojunction anode to perform photocatalytic oxidation degradation on the organic pollutants;

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

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

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

[0031] (1) preparing ZnO nano arrays on a conductive substrate by a sol-gel method;

[0032] (2) depositing a layer of silver sulfide (Ag2S) on the surface of the ZnO nano array by an ion exchange method 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 a MXene material on a substrate by a hydrothermal method to form a conductive layer;

[0036] (2) preparing a spinel ferrite (such as CoFe2O4 or NiFe2O4) nano structure by a hydrothermal method;

[0037] (3) compounding the spinel ferrite with the MXene to form a heterojunction photo-cathode;

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

[0039] Further, the operation conditions include:

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

[0041] (2) the system is irradiated by simulated sunlight or visible light (wavelength λ>420 nm);

[0042] (3) an external circuit loading resistor or a potential controller is used to maintain a constant current density, and the photocurrent and reaction efficiency are monitored;

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

[0044] In combination with the above technical solutions and solved technical problems, the technical solutions to be protected by the application have the following advantages and positive effects:

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

[0046] Based on the reaction principle of PFC, if nitrate exists in wastewater, it can be used as a cathode electron acceptor, thereby realizing the reduction of nitrate pollutants to synthesize ammonia and the oxidation of organic pollutants, so that the two types of pollutants in the anode and cathode are removed synchronously. A photocatalytic cathode material with excellent adsorption performance and selective catalytic reduction activity is developed. Based on the construction of a new functional cathode PFC, the efficiency of nitrate removal will be improved, the energy consumption level will be reduced, and the treatment and resource utilization of wastewater containing nitrate and refractory organic pollutants will have important scientific value and application value.

[0047] Secondly, the technical solutions of the application fill the technical gap in the industry at home and abroad:

[0048] The implementation of the project will provide important scientific information and theoretical basis for the design of electricity-producing reactors based on composite pollutant control and the development of electrode materials, and deepen the understanding of the working principle of pollutant co-treatment, and obtain new knowledge in the field of environmental chemistry and nanocatalytic chemistry.

[0049] Thirdly, the technical solutions of the application solve 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 have made significant technical progress in the following aspects:

[0050] 1) Improved photocatalytic efficiency: By using Ag2S / ZnO as the anode material and combining Mxene / CoFe2O4 composite as the cathode, the overall catalytic performance of the photocatalytic fuel cell system is significantly enhanced. Mxene material has excellent electrical 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 ammonia synthesis.

[0051] 2) Enhanced material stability and durability: By synthesizing high-activity Ag2S / ZnO and Mxene / CoFe2O4 composite materials at lower temperatures, the invention avoids the damage to the material structure caused by high-temperature calcination, ensuring the stability and durability of the material during long-term use. Compared with traditional photocatalytic materials, the composite material in the invention can maintain good catalytic activity after multiple cycles, solving the problem of material deactivation in the prior art.

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

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

[0054] Overall, the invention has made significant technical progress in improving photocatalytic efficiency, enhancing material stability, achieving efficient treatment of multiple pollutants, and improving system applicability, and is expected to bring widespread application in the fields of environmental protection and industrial wastewater treatment. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 is a structure schematic diagram of a double-heterojunction electrode photocatalytic fuel cell system for simultaneous synthesis of ammonia for organic-inorganic pollutant treatment provided by the embodiment of the invention;

[0056] Figure 2The application provides an antibiotic degradation graph a and a nitrate reduction graph b for organic-inorganic pollutant treatment. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0058] The present application provides a PFC (a dual-heterojunction electrode photocatalytic fuel cell system for simultaneous synthesis of ammonia for organic-inorganic pollutant treatment) system. The device is composed of two photoelectrodes, an external loop, an electrolyte, a fuel and an ion exchange membrane. By selecting and optimizing different electrode materials, the present application can flexibly determine the applicable chemical reagents and materials according to the requirements of the application scene, so as to realize the multifunctional pollutant treatment effect. The photoanode of the photocatalytic fuel cell system for pollutant treatment based on the heterojunction structure is specially used for oxidizing refractory organic pollutants such as antibiotics, and the photocathode is used for reducing nitrate pollutants.

[0059] Firstly, 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 surface of ZnO, the catalytic ability of the anode in the process of oxidizing antibiotic molecules is effectively improved, so as to significantly improve the photoelectric conversion efficiency. The photocatalytic fuel cell system for pollutant treatment based on the heterojunction structure shows higher efficiency in practical application.

[0060] Secondly, the photocathode adopts a heterojunction constructed by metal Ti3C2 (MXene) and spinel ferrite. Ti3C2 (MXene) becomes an ideal photocathode material due to its excellent conductivity and catalytic performance, and the spinel ferrite forms a structure with different double-metal components by changing the type of precursor metal. Through accurate design, the composite material forms a double-component cocatalyst, which significantly enhances the electron transfer capacity, catalytic activity and selectivity of the cathode.

[0061] Through accurate design and application of the double-component cocatalyst, the composite ratio of Ti3C2 and spinel ferrite is optimized, so that the photocathode exhibits stronger catalytic activity in the process of reducing nitrate pollutants. This design not only enhances the reduction capacity of the photocathode, but also effectively reduces the overall resistance of the photocatalytic fuel cell system for pollutant treatment based on the heterojunction structure, thereby improving the energy conversion efficiency of the device and increasing the practicability and stability of the device.

[0062] In addition, the present application 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, ensuring the reliability and repeatability of the test results, facilitating subsequent research and application promotion.

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

[0064] Simultaneous ammonia synthesis during pollutant treatment is another innovation of the present application. The present application selects wastewater containing nitrate and antibiotics as the electrolyte and achieves simultaneous ammonia synthesis through selective regulation of the cathode material. This design demonstrates the broad application prospects of the heterojunction structure-based photocatalytic fuel cell system for pollutant treatment, providing an efficient and multifunctional solution for environmental pollution control and green energy production.

[0065] The heterojunction structure-based photocatalytic fuel cell system for pollutant treatment of the present application has achieved significant improvements in pollutant treatment efficiency, photoelectric conversion performance, material stability, and overall energy utilization rate of the device. This innovative design not only improves the practicality and stability of the equipment, but also makes the heterojunction structure-based photocatalytic fuel cell system 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) is used as the substrate, and ZnO nanor arrays are deposited on the surface of the substrate by sol-gel method.

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

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

[0071] 2. Cathode preparation:

[0072] MXene nanosheets are deposited on the conductive substrate by hydrothermal method, forming a good conductive layer.

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

[0074] 3. Operating conditions:

[0075] 10 ppm antibiotic-containing wastewater is added to the anode chamber and 1 M nitrate solution is added to the cathode chamber.

[0076] Nafion membrane is used to separate the two chambers and the photocatalytic fuel cell system is exposed to visible light radiation (λ>420 nm).

[0077] An external circuit is loaded with a 10 Ω resistor and the photocurrent and voltage are recorded.

[0078] 4. Results:

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

[0080] The removal rate of nitrate in the cathode chamber reaches 92% and the selectivity of ammonia synthesis is 87%.

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

[0082] 1. Anode preparation:

[0083] ZnO nanorod arrays are prepared on a titanium mesh substrate by sol-gel method.

[0084] An Ag2S layer is deposited on the surface of the ZnO by liquid deposition method to form a high-efficiency photocatalytic anode.

[0085] Drying and annealing are performed to enhance the structural performance.

[0086] 2. Cathode preparation:

[0087] MXene material is deposited on a carbon fiber cloth substrate by hydrothermal method.

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

[0089] 3. Operating conditions:

[0090] 50 ppm endocrine disruptor bisphenol A-containing wastewater is added to the anode chamber and 0.5 M nitrate solution is added to the cathode chamber.

[0091] Nafion membrane is used to separate the two chambers and the system is operated under a solar simulator (100 mW / cm 2 ).

[0092] An 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 removal rate of nitrate in the cathode chamber was 88%, and the selectivity of synthetic ammonia reached 85%. The above describes a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement and improvement within the technical range disclosed by the present application and within the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A dual heterojunction electrode photocatalytic fuel cell system for simultaneous ammonia synthesis from organic-inorganic pollutants, characterized in that, This system uses an Ag2S / ZnO nanoarray heterojunction structure instead of ZnO nanoparticles as the anode material: The anode is composed of an 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, thereby improving the photoelectric conversion efficiency of the anode. The cathode material is a heterojunction structure constructed by MXene-based material and spinel ferrite. Carbon material is deposited on the substrate by a hydrothermal method, and then combined with spinel ferrite prepared by a hydrothermal method to form a photocathode. The anode chamber reaction solution is a solution of recalcitrant organic pollutants, including antibiotics, endocrine disruptors, and perfluorinated compounds. The cathode chamber is a nitrate solution. A Nafion membrane separates the cathode and anode chambers. The external circuit uses silver-plated copper wires to connect the load.

2. The dual heterojunction electrode photocatalytic fuel cell system for simultaneous ammonia synthesis from organic-inorganic pollutants as described in claim 1, characterized in that, The fuel cell is constructed based on a PFC system and includes a heterojunction dual photoelectrode, an external circuit, an electrolyte, fuel, and an ion exchange membrane. The PFC is used in a dual heterojunction electrode photocatalytic fuel cell for the simultaneous synthesis of ammonia from organic and inorganic pollutants. The binary photoanode employs a nanoarray ZnO heterojunction structure. By precisely controlling the arrangement and surface modification of the ZnO nanoarray, a photoanode with high specific surface area and enhanced light absorption capacity is constructed, which significantly improves the catalytic oxidation efficiency of the photoanode. Furthermore, the separation and migration process of electron-hole pairs are optimized at the nanoscale, thereby greatly improving the photoelectric conversion efficiency. The binary photocathode is composed of a heterojunction structure of metallic Ti3C2 MXene and spinel ferrite. By introducing different precursor metals, a variety of bimetallic spinel ferrites are prepared. Combining the high conductivity of Ti3C2 MXene and the strong photocatalytic reduction ability of spinel ferrite, a two-component cocatalyst is formed. This heterojunction structure optimizes the nitrate reduction reaction pathway by regulating the electronic band structure and surface activity of the photocathode, and improves the activity and selectivity of nitrate reduction to ammonia synthesis. The connection between the anode and cathode has been precisely optimized to ensure efficient transport of photogenerated carriers. By adjusting the conduction band and valence band of the binary heterojunction anode, the fuel cell can achieve efficient redox reactions without the application of external voltage, effectively improving the overall energy utilization and electrochemical stability of the device.

3. The dual heterojunction electrode photocatalytic fuel cell system for simultaneous ammonia synthesis from organic-inorganic pollutants as described 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, which is focused onto the anode surface through a lens system for photocatalytic reaction; The fuel cell device adopts a modular design. The anode module, cathode module, and electrolyte module can all be disassembled and replaced independently. 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 hold electrolytes of different volumes and compositions, making it suitable for different experimental conditions. The ion exchange membrane has a multilayer structure, with the outermost layer being a Nafion membrane and the innermost layer being an anion exchange membrane. The membrane material is sulfonated polyether ether ketone SPEEK or perfluorosulfonic acid resin, and the membrane thickness is 50μm-200μm. It is prepared by solution casting or hot pressing, and the membrane surface is treated with hydrophilicity to improve ion conductivity. The outer shell of the device is made of highly corrosion-resistant polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF) to ensure chemical stability during long-term use. All internal connections are made of silver wire or silver-plated copper wire to reduce resistance loss and enhance conductivity.

4. The dual heterojunction electrode photocatalytic fuel cell system for simultaneous ammonia synthesis from organic-inorganic pollutants as described in claim 1, characterized in that, Based on the reaction principle of PFC, nitrates present in wastewater are used as cathode electron acceptors to synergistically reduce nitrate pollutants to ammonia and oxidize organic pollutants, so that both anode and cathode pollutants are removed simultaneously.

5. A method for treating organic pollutants and simultaneously synthesizing ammonia, characterized in that, Includes the following steps: (1) Add a solution containing organic contaminants to the anode chamber, said organic contaminants including antibiotics, endocrine disruptors or perfluorinated compounds; (2) Add nitrate solution to the cathode chamber and separate the cathode and anode chambers through a Nafion membrane; (3) Under light source irradiation, organic pollutants are photocatalytically oxidized and degraded using Ag2S / ZnO heterojunction anode; (4) Ammonia is generated during nitrate reduction using an MXene / spinel ferrite heterojunction cathode; (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 anode preparation steps include: (1) ZnO nanoarrays were prepared on a conductive substrate by sol-gel method; (2) A layer of silver sulfide Ag2S is deposited on the surface of ZnO nanoarray to form an Ag2S / ZnO heterojunction structure; (3) Drying and annealing the heterojunction structure to improve photoelectric conversion efficiency.

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

8. The method according to claim 5, characterized in that, Operating conditions include: (1) The anode chamber solution is an organic pollutant solution with a concentration of 10-50 ppm, and the cathode chamber solution is a nitrate solution with a concentration of 0.5-1 M; (2) Irradiate the system by simulating sunlight or visible light; (3) The external circuit loads a resistor or connects 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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