Construction of CdS / TiO2-based photocatalytic fuel cell and application of CdS / TiO2-based photocatalytic fuel cell in treatment of organic wastewater

Abstract

The invention relates to the technical field of photocatalytic fuel cells, and particularly discloses construction of a CdS / TiO2-based photocatalytic fuel cell and application of the CdS / TiO2-based photocatalytic fuel cell in treatment of organic wastewater. The preparation method comprises the following steps: preparing a TiO2 photo-anode substrate, forming a CdS nano-particle layer on the surface of the substrate by adopting a chemical deposition method to construct a heterojunction, and performing photo-anode modification; coating a non-noble metal catalyst material on an FTO glass conductive substrate to prepare a photocathode; and assembling a double-chamber battery system, adding an electrolyte solution and connecting an external circuit. The spectral response range is expanded to a visible light region, and the light energy utilization rate is improved; photon-generated carrier separation and transmission are optimized, and the photocatalytic oxidation capacity is enhanced; the cost is reduced by adopting a non-noble metal catalyst; and the battery generates electric energy while degrading organic matters, so that energy recovery is realized, and remarkable environmental benefits and economic values are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field, in particular to the construction of a CdS / TiO2-based photocatalytic fuel cell and its application in treating organic wastewater. Background Art

[0002] Photocatalytic fuel cells (PFCs) are an environmental remediation technology that converts light energy into electricity and simultaneously degrades pollutants. Their core mechanism utilizes photoanode materials to generate photogenerated electron-hole pairs under illumination: holes oxidize pollutants, while electrons transfer via an external circuit to the photocathode to participate in reduction reactions (such as hydrogen production or oxygen reduction). Currently, TiO2 is widely used as a photoanode material due to its stability and non-toxicity. However, its wide bandgap (~3.2 eV) only responds to ultraviolet light (which accounts for 4% of the solar spectrum), resulting in low visible light utilization. To expand the spectral response range, researchers often use narrow-bandgap semiconductors (such as CdS, with a bandgap of ~2.4 eV) to construct heterojunctions with TiO2. However, CdS is susceptible to photocorrosion and lacks long-term stability. Photocathode catalysts often rely on precious metals (such as Pt), which are costly and scarce.

[0003] Moreover, although traditional photocatalytic technologies (such as pure TiO2 nanoparticles or films) can effectively degrade organic matter, the accumulation of pure TiO2 nanoparticles or the excessive thickness of the film result in sparse active sites, and the photogenerated electron-hole pairs quickly recombine in the bulk or on the surface and cannot effectively participate in the redox reaction.

[0004] Therefore, the construction of CdS / TiO2-based photocatalytic fuel cells and their application in treating organic wastewater are proposed to solve the current shortcomings. Summary of the Invention

[0005] In order to solve the problems of the prior art, the present invention provides a CdS / TiO2-based photocatalytic fuel cell construction and its application in treating organic wastewater.

[0006] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned technologies and provide a CdS / TiO2-based photocatalytic fuel cell construction and its application in treating organic wastewater.

[0007] To solve the above technical problems, the technical solution provided by the present invention is a method for constructing a CdS / TiO2-based photocatalytic fuel cell, comprising the following steps:

[0008] S1 photoanode preparation:

[0009] S1.1 Preparation of TiO2 photoanode substrate: Anodize a titanium sheet in a fluoride-containing electrolyte at a controlled voltage of 10-30 V for 10-60 min to form a TiO2 nanotube array, followed by sintering at 400-550°C for 2-4 hours.

[0010] S1.2 Preparation of CdS / TiO2 heterojunction: Immerse the prepared TiO2 photoanode substrate material in a CdS / TiO2 heterojunction. 2+ and S 2- In the precursor solution, a uniformly distributed CdS nanoparticle layer is formed on the surface of the TiO2 substrate through a chemical deposition reaction, forming a CdS / TiO2 heterojunction;

[0011] S1.3 Photoanode modification: Graphene oxide dispersion was spin-coated on the CdS / TiO2 surface at a speed of 2000-4000 rpm with a thickness of 0.1-1 μm, and then reduced at 150-250 °C to obtain the rGO-CdS / TiO2 composite electrode;

[0012] S2 photocathode preparation: Disperse the non-precious metal catalyst material in the carrier solution, apply it on the FTO glass conductive substrate and dry and solidify it;

[0013] S3 assembles a dual-chamber battery system: the photoanode and photocathode are placed in two separate chambers, separated by a proton exchange membrane;

[0014] S4: adding electrolyte solution: injecting a solution containing 0.1-0.2 mol / L sodium sulfate or sodium carbonate into the chamber, and adjusting the pH value of the solution to 6-8;

[0015] S5 connects to the external circuit: connects the photoanode and the photocathode through a wire to form a closed loop, and sets a current collector.

[0016] As an improvement, the TiO2 substrate material in step S1.1 is an anatase TiO2 nanotube array, which is prepared on a conductive substrate by an anodic oxidation method, with a tube length of 50 to 200 μm and a tube diameter of 50 to 150 nm.

[0017] As an improvement, the loading amount of the CdS nanoparticles in step S1.2 is 0.1% to 10% by mass, and the chemical deposition reaction is carried out at a temperature of 40 to 60° C. for a reaction time of 30 to 120 min.

[0018] As an improvement, after step S1.2, it also includes spin coating a polyvinylidene fluoride film on the surface of the CdS / TiO2 heterojunction, with a film thickness of 0.5 to 5 μm.

[0019] As an improvement, the non-precious metal catalyst material in step S2 is polypyrrole or metal organic framework material, and the non-precious metal catalyst material is loaded on the FTO glass conductive substrate by solution impregnation or spraying to form a catalyst film with a thickness of 50 to 300 μm.

[0020] As an improvement, the chambers of the dual-chamber battery system in step S3 are made of heat-resistant glass or polytetrafluoroethylene material, and the proton exchange membrane is fixed between the chambers by hot pressing or bonding. The temperature of the hot pressing method is 100-150°C and the pressure is 0.5-1.5MPa.

[0021] The present invention also provides a CdS / TiO2-based photocatalytic fuel cell prepared by the above method.

[0022] The present invention also provides the application of the CdS / TiO2-based photocatalytic fuel cell prepared by the above method in treating organic wastewater.

[0023] As an improvement, the organic wastewater is wastewater containing dyes, antibiotics, phenolic compounds or pesticides, and the COD value of the organic wastewater ranges from 50 to 1000 mg / L.

[0024] As an improvement, the specific operation of the organic wastewater treatment is:

[0025] Organic wastewater is injected into the battery chamber as an electrolyte solution; the light source irradiation system is started to provide visible light irradiation to the surface of the photoanode with a wavelength range of 420 to 600 nm; the reaction begins, and the CdS / TiO2 heterojunction material on the surface of the photoanode absorbs visible light to generate photogenerated electrons and holes; the photogenerated electrons migrate from the CdS conduction band to the TiO2 conduction band and flow to the photocathode through an external circuit; the photogenerated holes remain in the CdS valence band and directly oxidize organic matter or react with water to generate active oxygen species; the catalyst on the surface of the photocathode receives electrons and converts H + Reduction to hydrogen; reactive oxygen species degrade organic matter and mineralize it into harmless substances such as CO2 and H2O; the generated electrical energy is collected through an external circuit.

[0026] The advantages of the present invention compared with the prior art are:

[0027] 1. Significantly improved photocatalytic performance: Through the design of CdS / TiO2 heterojunction structure, the spectral response range is effectively broadened to the visible light band, and the ability to generate photogenerated carriers is enhanced; the introduction of reduced graphene oxide (rGO) coating layer forms an efficient electron conduction network, significantly reducing the recombination rate of photogenerated electrons and holes, and improving the charge separation efficiency.

[0028] 2. Comprehensively enhanced system stability: A polyvinylidene fluoride (PVDF) membrane is used to cover the heterojunction interface, effectively inhibiting CdS photocorrosion and isolating electrolyte erosion; the anatase TiO2 nanotube array substrate is strengthened by high-temperature sintering to improve mechanical strength and cycle stability.

[0029] 3. Significantly reduced manufacturing costs: The photocathode uses non-precious metal catalysts such as polypyrrole or metal-organic framework materials to completely replace precious metals, significantly reducing material costs; the photocathode is prepared by chemical deposition loading CdS and solution immersion spraying, avoiding high-energy consumption processes and simplifying the preparation process.

[0030] 4. Optimized and efficient battery structure: The dual-chamber design combined with the proton exchange membrane separator effectively prevents direct electron-hole recombination while ensuring efficient proton transmission; the proton exchange membrane is fixed by hot pressing and bonding to enhance sealing and interface contact, thereby reducing the internal resistance of the system.

[0031] 5. Wide applicability of wastewater treatment: simultaneous realization of organic matter mineralization and hydrogen energy recovery, expanding energy recovery channels; suitable for highly toxic and complex wastewater (such as antibiotics and pesticides), and no secondary pollution during the degradation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a diagram showing the wastewater removal effect of the CdS / TiO2-based photocatalytic fuel cell construction of the present invention and its application in treating organic wastewater under conditions of different CdS loading amounts. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0035] In this application, unless otherwise stated, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0037] The method for constructing a CdS / TiO2-based photocatalytic fuel cell comprises the following steps:

[0038] S1 photoanode preparation:

[0039] S1.1 Prepare the TiO2 photoanode substrate by constructing a highly ordered, anatase phase TiO2 nanotube array on the titanium sheet surface to provide a high specific surface area substrate and efficient electron transmission channel for CdS loading.

[0040] Specifically, a titanium sheet is placed in a fluoride-containing electrolyte for anodization, with a controlled voltage of 10 to 30 V and an oxidation time of 10 to 60 minutes to form a TiO2 nanotube array, which is then sintered at 400 to 550° C. for 2 to 4 hours;

[0041] In this embodiment, the fluoride-containing compound is 0.3-0.5 wt% NH4F dissolved in a glycol-water mixture, wherein the volume ratio of NH4F to the glycol-water mixture is 9:1;

[0042] During implementation, when the titanium sheet is placed as an anode in a fluoride-containing electrolyte, under the action of an applied voltage, the titanium atoms on the surface of the titanium sheet are oxidized, and an anode reaction occurs:

[0043] Ti + 2H2O → TiO2 + 4H + +4e -

[0044] Titanium atoms lose electrons to form Ti 4+ , with H2O or OH in the electrolyte - The combination forms an amorphous TiO2 layer.

[0045] F in the electrolyte - Directional dissolution of TiO2 to form nanotube structure:

[0046] TiO 2 +6F - +4H + →[TiF6] 2 +2H2O

[0047] During the anodic oxidation process, the fluoride ions (F-) and oxygen ions (O 2- ) migrate to the surface of the titanium sheet under the action of the electric field;

[0048] The titanium sheet acts as an anode. Under the action of the electric field, the titanium atom (Ti) loses electrons and becomes Ti 4+ ions and dissolve into the electrolyte;

[0049] Ti 4+ ions and oxygen ions (O 2- ) combines to form a dense TiO2 oxide film on the surface of the titanium sheet, which is called a barrier layer and prevents further oxidation reaction.

[0050] As the oxidation reaction proceeds, the electric field strength to which the barrier layer is subjected increases, causing the barrier layer to partially dissolve and form micropores. Under the action of the electric field, fluoride ions accelerate the dissolution process of the barrier layer, forming an irregular micropore structure. The electric field strength at the bottom of the micropores is high, causing the micropores to continue to deepen and widen. As the micropores deepen, the area between the pores continues to grow and dissolve due to the action of the electric field, eventually forming a nanotube array structure.

[0051] At the same time, sintering treatment can promote the crystallization of TiO2 nanotubes, transforming them from amorphous or partially crystalline states to anatase crystal structure. Anatase TiO2 has high photocatalytic activity and stability, and can absorb ultraviolet light and generate photogenerated electron-hole pairs.

[0052] Furthermore, the TiO2 nanotube array formed after anodization is sintered at 400-550°C for 2-4 hours to remove organic matter and other impurities that may remain in the electrolyte, thereby improving the purity of the TiO2 nanotubes.

[0053] In addition, the sintering treatment can also enhance the adhesion between TiO2 nanotubes and the titanium substrate, preventing the nanotubes from falling off during the subsequent chemical deposition and photocatalytic reaction.

[0054] In this embodiment, the TiO2 nanotube array formed on the TiO2 photoanode substrate has a tube length of 50 to 200 μm, a tube diameter of 50 to 150 nm, and a specific surface area of ​​150 to 300 m 2 / g, the tube wall thickness is 10-50nm, and the porosity is 60%-90%.

[0055] TiO2 nanotube arrays are formed into vertically aligned tubular structures through anodic oxidation, significantly increasing the specific surface area and providing more active sites. Furthermore, the orderly arrangement of the nanotubes in the TiO2 nanotube array prevents agglomeration caused by particle accumulation, while providing a directional transmission channel for photogenerated electrons and reducing recombination.

[0056] In practice, longer nanotubes can increase the light absorption path of the photoanode and improve the efficiency of capturing ultraviolet light. However, although longer tube length increases light absorption, it also increases the distance of electron transmission. The tube length range of 50 to 200 μm can minimize electron transmission loss while ensuring sufficient light absorption.

[0057] At the same time, a smaller tube diameter can increase the specific surface area of ​​the nanotube array, providing more active sites for photocatalytic reactions and charge transfer, helping to improve the collection efficiency of photogenerated electrons and the adsorption capacity of reactants. However, while a smaller tube diameter increases the specific surface area, it also makes the nanotube structure more fragile, making it prone to collapse or breakage during preparation or use. Therefore, a tube diameter range of 50 to 150 nm can achieve a relative balance between specific surface area and structural stability.

[0058] S1.2 Preparation of CdS / TiO2 heterojunction: forming a uniformly distributed CdS nanoparticle layer on the surface of the TiO2 substrate by chemical deposition, thereby forming a heterojunction structure;

[0059] Specifically, the prepared TiO2 photoanode substrate is immersed in a Cd 2+ and S 2- In the precursor solution, in this embodiment, the precursor solution uses Cd(NO3)2, and a uniformly distributed CdS nanoparticle layer is formed on the surface of the TiO2 substrate through a chemical deposition reaction to form a CdS / TiO2 heterojunction;

[0060] The chemical deposition reaction is carried out at a temperature of 40 to 60° C., and the reaction time is 30 to 120 minutes.

[0061] Specifically, the hydroxyl groups (-OH) on the TiO2 surface act as active sites to adsorb Cd 2+:

[0062] Ti-OH+Cd 2+ →Ti-O-Cd 2+ +H +

[0063] Then S 2- Attack CD + Location:

[0064] Ti-O-Cd + +S 2 →Ti-O-Cd-S -

[0065] At a temperature of 40-60°C, Cd and S ions react chemically in the solution to form CdS nanoparticles:

[0066] Cd 2+ +S 2- →CdS↓

[0067] Furthermore, the loading amount of CdS nanoparticles is 0.1% to 10% by mass. The deposition amount of CdS nanoparticles can be controlled by adjusting the concentration of the precursor solution and the time of the chemical deposition reaction.

[0068] In practice, a lower loading amount (eg, 0.1%) is suitable for preliminary modification of the photoanode surface to increase certain active sites.

[0069] A higher loading amount (such as 10%) can cover more TiO2 surfaces and enhance light absorption capacity, but it should be noted that too high a loading amount may cause particle agglomeration and affect photocatalytic performance.

[0070] The method also includes spin coating a polyvinylidene fluoride film on the surface of the CdS / TiO2 heterojunction, with a film thickness of 0.5 to 5 μm.

[0071] The polyvinylidene fluoride film can serve as a protective layer to prevent the CdS / TiO2 heterojunction from being physically damaged and chemically corroded during subsequent chemical reactions or use, thereby extending the service life of the photoanode.

[0072] Moreover, polyvinylidene fluoride, a chemically stable polymer, can enhance the stability of the photoanode in the electrolyte solution when coated on the surface of the CdS / TiO2 heterojunction, reducing performance degradation caused by interfacial reactions. It can also improve the interfacial contact between the electrode and the electrolyte, reduce interfacial resistance, and improve charge transfer efficiency.

[0073] S1.3 Photoanode modification: The graphene oxide dispersion is spin-coated on the CdS / TiO2 surface at a rotation speed of 2000-4000 rpm and a thickness of 0.1-1 μm. The spin coating method can ensure that the graphene oxide dispersion is evenly covered on the surface of the photoanode to form a uniform thin film. After reduction treatment at 150-250°C, the rGO-CdS / TiO2 composite electrode is obtained. The reduction treatment can remove the oxygen-containing functional groups in the graphene oxide, restore its partial graphene structure, and significantly improve its conductivity and chemical stability.

[0074] The rGO-CdS / TiO2 composite electrode formed by rGO coating uses rGO to form a conductive network on the surface of the CdS / TiO2 heterojunction, reducing the resistance of photogenerated electron transmission, improving the electron collection efficiency, and helping to reduce the recombination of electrons and holes, thereby enhancing the photocatalytic performance.

[0075] Specifically, the work function of rGO is between the conduction band of CdS and the conduction band of TiO2, forming a stepped band structure, which drives the electrons to migrate from CdS to rGO and then to TiO2. 2 The carbon network provides a high-mobility electron channel and suppresses hole backflow through the Schottky barrier formed at the CdS interface, significantly improving the charge separation efficiency.

[0076] At the same time, rGO coating can enhance the chemical stability of the photoanode, prevent CdS nanoparticles from falling off or agglomerating during long-term use, and extend the service life of the photoanode.

[0077] In addition, the rGO layer can improve the interfacial contact between the photoanode and the electrolyte, reduce the interfacial resistance, and improve the charge transfer efficiency. In addition, rGO can also serve as a protective layer to prevent the photoanode surface from being corroded by the electrolyte.

[0078] S2 photocathode preparation, by loading non-precious metal catalyst materials on FTO glass conductive substrate, prepares efficient photocathode catalyst film, providing guarantee for the efficient operation of photocatalytic fuel cells.

[0079] Specifically, the non-noble metal catalyst material is dispersed in a carrier solution, coated on a FTO glass conductive substrate and dried and solidified;

[0080] The non-precious metal catalyst material is polypyrrole or metal organic framework material, and the non-precious metal catalyst material is loaded on the FTO glass conductive substrate by solution impregnation or spraying to form a catalyst film with a thickness of 50 to 300 μm.

[0081] In this embodiment, the non-precious metal catalyst material is a metal organic framework material, specifically ZIF-67, which has a highly ordered porous structure and an adjustable chemical composition and can provide abundant active sites.

[0082] The combination of non-precious metal catalyst materials and the FTO glass conductive substrate can improve the conductivity of the photocathode and promote the rapid transmission of electrons. At the same time, the non-precious metal catalyst material has abundant active sites and can effectively catalyze the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), thereby improving the performance of photocatalytic fuel cells.

[0083] S3 assembled a dual-chamber battery system, ensuring the effective separation of the photoanode and photocathode, and achieving rapid proton conduction through the proton exchange membrane.

[0084] Specifically, the photoanode and photocathode are placed in two independent chambers, which are separated by a proton exchange membrane;

[0085] During implementation, the chamber of the dual-chamber battery system is made of heat-resistant glass or polytetrafluoroethylene material, which has good chemical stability and mechanical strength and can maintain structural stability during long-term use.

[0086] The proton exchange membrane is fixed between the chambers by hot pressing or bonding. In this embodiment, the proton exchange membrane is fixed between the chambers by hot pressing. The temperature of the hot pressing method is 100-150°C and the pressure is 0.5-1.5Ma, which can form a tight bond between the proton exchange membrane and the chamber material, ensuring good contact and sealing between the membrane and the chamber.

[0087] In specific implementation, the proton exchange membrane can separate the photoanode and photocathode, preventing the direct recombination of electrons and holes, thereby improving the photocatalytic efficiency; the proton exchange membrane mainly conducts protons (H + In a photocatalytic fuel cell, protons generated by the photoanode are rapidly conducted to the photocathode through a proton exchange membrane, forming a closed loop.

[0088] In this embodiment, the proton exchange membrane is made of perfluorosulfonic acid resin, and the sulfonic acid group (-SO3 - H + ) provides a fixed negative charge, adsorbs water molecules and forms a proton conduction channel; the photogenerated holes generated by the photoanode oxidize organic matter to generate H + , protons migrate through the membrane to the photocathode to participate in HER (hydrogen evolution).

[0089] S4 adds electrolyte solution: injects a solution containing 0.1-0.2 mol / L sodium sulfate or sodium carbonate into the chamber. The electrolyte solution dissociates into corresponding ions in water, which can provide good ionic conductivity.

[0090] The pH value of the solution is adjusted to 6 to 8, and the pH value of the electrolyte solution is adjusted to a neutral to weakly alkaline range, which helps to maintain the stability of the photoanode and the photocathode and promotes the progress of the photocatalytic reaction.

[0091] By adding the electrolyte solution, a medium for ion transport is provided to ensure that the protons (H + ) can quickly migrate through the solution to the proton exchange membrane and then reach the photocathode, helping to form a closed electrical circuit and maintain the operation of the photocatalytic fuel cell.

[0092] At the same time, the ions in the electrolyte solution can balance the charge generated during the electrode reaction, maintain the electrical neutrality inside the battery, and thus improve the stability and efficiency of the battery.

[0093] S5 connects to the external circuit: connects the photoanode and the photocathode through a wire to form a closed loop, and sets a current collector.

[0094] Specifically, the photoanode and the photocathode are connected by a wire to form a closed electrical circuit, so that the photogenerated electrons generated by the photoanode can flow to the photocathode through the wire and participate in the electrochemical reaction.

[0095] A current collector is provided in the circuit to collect and guide the current so as to measure and apply the output performance of the battery.

[0096] During use, after the photoanode and photocathode are connected to an external circuit, the photocatalytic fuel cell can convert light energy into electrical energy under light conditions and output the electrical energy for use by external devices.

[0097] At the same time, by connecting the external circuit and the current collector, instruments such as ammeters and voltmeters can be used to monitor and analyze the battery's performance indicators such as output current, voltage and power in real time, providing data support for battery optimization and evaluation.

[0098] The present invention also provides a CdS / TiO2-based photocatalytic fuel cell prepared by the above method.

[0099] The present invention also provides the application of the CdS / TiO2-based photocatalytic fuel cell prepared by the above method in treating organic wastewater.

[0100] The photogenerated electrons and holes generated by the photoanode can effectively stimulate the catalyst activity, promoting the decomposition of organic pollutants into harmless substances such as carbon dioxide and water. The construction of the CdS / TiO2 heterojunction broadens the spectral response range and enhances the generation of photogenerated carriers, thereby improving the degradation efficiency.

[0101] Specifically, in the photoanode, TiO2 nanotube arrays and CdS nanoparticles absorb photon energy to generate photogenerated electrons (e - ) and holes (h+). TiO2 mainly absorbs ultraviolet light, while CdS can absorb visible light, thus broadening the spectral response range.

[0102] Photogenerated electrons flow to the photocathode through the external circuit and participate in the reduction reaction; photogenerated holes remain at the photoanode and participate in the oxidation reaction.

[0103] The holes generated by the photoanode have strong oxidizing properties and can directly oxidize organic pollutants or react with water to generate hydroxyl radicals (·OH), which further oxidize organic matter.

[0104] At the photocathode, a non-precious metal catalyst catalyzes a reduction reaction, typically the hydrogen evolution reaction (HER) or the oxygen reduction reaction (ORR), depending on the composition of the wastewater.

[0105] In this embodiment, the organic wastewater is wastewater containing dyes, antibiotics, phenolic compounds or pesticides, and the COD value of the organic wastewater ranges from 50 to 1000 mg / L.

[0106] Specifically, for dye wastewater, the hydroxyl radicals (·OH) generated by the photoanode can quickly attack the conjugated double bond structure in the dye molecules, destroying their chromophores and achieving decolorization. At the same time, they can further oxidize and degrade the dye molecules, decomposing them into inorganic substances such as carbon dioxide and water, completing the mineralization process.

[0107] Regarding antibiotic wastewater, antibiotic molecules usually have complex ring structures. Photogenerated holes and hydroxyl radicals can destroy the above structures, causing them to lose their biological activity and decompose into small molecular organic matter, which is eventually mineralized into carbon dioxide and water, reducing their persistence and bioaccumulation in the environment.

[0108] For phenolic compound wastewater, phenolic compounds undergo hydroxylation reaction under the action of hydroxyl radicals to generate quinone intermediates, which are further oxidized and decomposed into carbon dioxide and water.

[0109] For pesticide wastewater, the functional groups in the pesticide molecules (such as amino groups, ester groups, etc.) are oxidized under the action of photogenerated holes and hydroxyl radicals, destroying their toxic structure and ultimately decomposing the pesticides into non-toxic carbon dioxide and water.

[0110] Dye wastewater can be decomposed into complex organic molecular structures through photocatalysis to achieve decolorization and mineralization; difficult-to-degrade antibiotics in antibiotic wastewater can also be effectively decomposed to reduce their environmental hazards; organic pollutants such as phenolic compounds and pesticides can also be efficiently degraded, making it suitable for a variety of wastewater treatment scenarios.

[0111] The application of CdS / TiO2-based photocatalytic fuel cells in the treatment of organic wastewater. The specific operations of organic wastewater treatment are:

[0112] Organic wastewater is injected into the battery chamber as an electrolyte solution; the light source irradiation system is started to provide visible light irradiation to the surface of the photoanode with a wavelength range of 420 to 600 nm; the reaction begins, and the CdS / TiO2 heterojunction material on the surface of the photoanode absorbs visible light to generate photogenerated electrons and holes; the photogenerated electrons migrate from the CdS conduction band to the TiO2 conduction band and flow to the photocathode through an external circuit; the photogenerated holes remain in the CdS valence band and directly oxidize organic matter or react with water to generate active oxygen species; the catalyst on the surface of the photocathode receives electrons and converts H + Reduction to hydrogen; reactive oxygen species degrade organic matter and mineralize it into harmless substances such as CO2 and H2O; the generated electrical energy is collected through an external circuit.

[0113] Specifically, after the CdS / TiO2 heterojunction of the photoanode absorbs visible light, photogenerated electrons migrate from the CdS conduction band to the TiO2 conduction band, effectively separating electrons and holes, reducing carrier recombination, and improving photocatalytic efficiency. The photogenerated holes remain in the CdS valence band, directly oxidizing organic matter or reacting with water to form reactive oxygen species, such as hydroxyl radicals (·OH) and hydrogen peroxide (H2O2). These reactive oxygen species have strong oxidizing properties and can efficiently degrade organic pollutants, gradually mineralizing complex organic molecules into harmless substances such as carbon dioxide and water.

[0114] Example 1:

[0115] The method for constructing a CdSTiO2-based photocatalytic fuel cell comprises the following steps:

[0116] S1 photoanode preparation:

[0117] S1.1 Preparation of TiO2 photoanode substrate: Anodize a titanium sheet in a fluoride-containing electrolyte at a controlled voltage of 10 V for 10 min to form a TiO2 nanotube array, followed by sintering at 400°C for 2 h.

[0118] Specifically, the TiO2 substrate material is anatase TiO2 nanotube array, which is prepared on a conductive substrate by an anodic oxidation method, with a tube length of 50 μm and a tube diameter of 50 nm.

[0119] S1.2 Preparation of CdS / TiO2 heterojunction: Immerse the prepared TiO2 photoanode substrate material in a CdS / TiO2 heterojunction. 2+ and S 2- In the precursor solution, a uniformly distributed CdS nanoparticle layer is formed on the surface of the TiO2 substrate through a chemical deposition reaction, forming a CdS / TiO2 heterojunction;

[0120] Specifically, the chemical deposition reaction is carried out at a temperature of 40° C., the reaction time is 30 min, and the loading amount of the CdS nanoparticles is 0.1% by mass.

[0121] The method also includes spin coating a polyvinylidene fluoride film on the surface of the CdS / TiO2 heterojunction, with a film thickness of 0.5 μm.

[0122] S1.3 Photoanode modification: Graphene oxide dispersion was spin-coated on the CdS / TiO2 surface at a speed of 2000 rpm and a thickness of 0.1 μm, and then reduced at 150 °C to obtain the rGO-CdS / TiO2 composite electrode;

[0123] S2 photocathode preparation: Disperse the non-precious metal catalyst material in the carrier solution, apply it on the FTO glass conductive substrate and dry and solidify it;

[0124] Specifically, the non-precious metal catalyst material is polypyrrole or metal organic framework material, and the non-precious metal catalyst material is loaded on the conductive substrate by solution impregnation or spraying to form a catalyst film with a thickness of 50.

[0125] In this embodiment, the non-noble metal catalyst material is a metal organic framework material, and the non-noble metal catalyst material is loaded on the FTO glass conductive substrate by a solution impregnation method.

[0126] S3 assembles a dual-chamber battery system: the photoanode and photocathode are placed in two separate chambers, separated by a proton exchange membrane;

[0127] The chambers of the dual-chamber battery system are made of heat-resistant glass or polytetrafluoroethylene material, and the proton exchange membrane is fixed between the chambers by hot pressing or bonding. In this embodiment, the proton exchange membrane is fixed between the chambers by hot pressing, and the temperature of the hot pressing method is 100°C and the pressure is 0.5MPa.

[0128] S4: adding electrolyte solution: injecting a solution containing 0.1 mol / L sodium sulfate or sodium carbonate into the chamber, and adjusting the pH value of the solution to 6;

[0129] S5 connects to the external circuit: connects the photoanode and the photocathode through a wire to form a closed loop, and sets a current collector.

[0130] The present invention also provides a CdS / TiO2-based photocatalytic fuel cell prepared by the above method.

[0131] The present invention also provides the application of the CdS / TiO2-based photocatalytic fuel cell prepared by the above method in treating organic wastewater.

[0132] Organic wastewater is wastewater containing dyes, antibiotics, phenolic compounds or pesticides, and the COD value of the organic wastewater is in the range of 50 mg / L.

[0133] The application of CdS / TiO2-based photocatalytic fuel cells in the treatment of organic wastewater. The specific operation of organic wastewater treatment is as follows: injecting organic wastewater as an electrolyte solution into the cell chamber; starting the light source irradiation system to provide visible light irradiation to the surface of the photoanode with a wavelength range of 420nm; starting the reaction, the CdS / TiO2 heterojunction material on the surface of the photoanode absorbs visible light to generate photogenerated electrons and holes; the photogenerated electrons migrate from the CdS conduction band to the TiO2 conduction band and flow to the photocathode through the external circuit; the photogenerated holes remain in the CdS valence band and directly oxidize organic matter or react with water to generate active oxygen species; the catalyst on the surface of the photocathode receives electrons and converts H + Reduction to hydrogen; reactive oxygen species degrade organic matter and mineralize it into harmless substances such as CO2 and H2O; the generated electrical energy is collected through an external circuit.

[0134] Example 2:

[0135] The method for constructing a CdS / TiO2-based photocatalytic fuel cell comprises the following steps:

[0136] S1 photoanode preparation:

[0137] S1.1 Preparation of TiO2 photoanode substrate: Anodize a titanium sheet in a fluoride-containing electrolyte at a controlled voltage of 20 V for 35 min to form a TiO2 nanotube array, followed by sintering at 475°C for 3 h.

[0138] Specifically, the TiO2 substrate material is an anatase TiO2 nanotube array, which is prepared on a conductive substrate by an anodic oxidation method, with a tube length of 125 μm and a tube diameter of 100 nm.

[0139] S1.2 Preparation of CdS / TiO2 heterojunction: Immerse the prepared TiO2 photoanode substrate material in a CdS / TiO2 heterojunction. 2+ and S 2- In the precursor solution, a uniformly distributed CdS nanoparticle layer is formed on the surface of the TiO2 substrate through a chemical deposition reaction, forming a CdS / TiO2 heterojunction;

[0140] Specifically, the chemical deposition reaction is carried out at a temperature of 50° C., the reaction time is 75 min, and the loading amount of the CdS nanoparticles is 5% by mass.

[0141] The method also includes spin coating a polyvinylidene fluoride film on the surface of the CdS / TiO2 heterojunction, with a film thickness of 2.5 μm.

[0142] S1.3 Photoanode modification: Graphene oxide dispersion was spin-coated on the CdS / TiO2 surface at a speed of 3000 rpm and a thickness of 0.5 μm, and then reduced at 200 °C to obtain the rGO-CdS / TiO2 composite electrode;

[0143] S2 photocathode preparation: Disperse the non-precious metal catalyst material in the carrier solution, apply it on the FTO glass conductive substrate and dry and solidify it;

[0144] Specifically, the non-precious metal catalyst material is polypyrrole or metal organic framework material, and the non-precious metal catalyst material is loaded on the conductive substrate by solution impregnation or spraying to form a catalyst film with a thickness of 175 μm.

[0145] In this embodiment, the non-noble metal catalyst material is a metal organic framework material, and the non-noble metal catalyst material is loaded on the FTO glass conductive substrate by a solution impregnation method.

[0146] S3 assembles a dual-chamber battery system: the photoanode and photocathode are placed in two separate chambers, separated by a proton exchange membrane;

[0147] The chambers of the dual-chamber battery system are made of heat-resistant glass or polytetrafluoroethylene material, and the proton exchange membrane is fixed between the chambers by hot pressing or bonding. In this embodiment, the proton exchange membrane is fixed between the chambers by hot pressing, and the temperature of the hot pressing method is 125°C and the pressure is 1.0 MPa.

[0148] S4: adding electrolyte solution: injecting a solution containing 0.15 mol / L sodium sulfate or sodium carbonate into the chamber, and adjusting the pH value of the solution to 7;

[0149] S5 connects to the external circuit: connects the photoanode and the photocathode through a wire to form a closed loop, and sets a current collector.

[0150] The present invention also provides a CdS / TiO2-based photocatalytic fuel cell prepared by the above method.

[0151] The present invention also provides the application of the CdS / TiO2-based photocatalytic fuel cell prepared by the above method in treating organic wastewater.

[0152] Organic wastewater is wastewater containing dyes, antibiotics, phenolic compounds or pesticides, and the COD value of the organic wastewater is in the range of 525 mg / L.

[0153] The application of CdS / TiO2-based photocatalytic fuel cells in the treatment of organic wastewater. The specific operation of organic wastewater treatment is as follows: injecting organic wastewater as an electrolyte solution into the cell chamber; starting the light source irradiation system to provide visible light irradiation to the surface of the photoanode with a wavelength range of 510nm; starting the reaction, the CdS / TiO2 heterojunction material on the surface of the photoanode absorbs visible light to generate photogenerated electrons and holes; the photogenerated electrons migrate from the CdS conduction band to the TiO2 conduction band and flow to the photocathode through the external circuit; the photogenerated holes remain in the CdS valence band and directly oxidize organic matter or react with water to generate active oxygen species; the catalyst on the surface of the photocathode receives electrons and converts H + Reduction to hydrogen; reactive oxygen species degrade organic matter and mineralize it into harmless substances such as CO2 and H2O; the generated electrical energy is collected through an external circuit.

[0154] Example 3:

[0155] The method for constructing a CdS / TiO2-based photocatalytic fuel cell comprises the following steps:

[0156] S1 photoanode preparation:

[0157] S1.1 Preparation of TiO2 photoanode substrate: Anodize a titanium sheet in a fluoride-containing electrolyte at a controlled voltage of 30 V for 60 min to form a TiO2 nanotube array, which is then sintered at 550°C for 4 h.

[0158] Specifically, the TiO2 substrate material is anatase TiO2 nanotube array, which is prepared on a conductive substrate by an anodic oxidation method, with a tube length of 200 μm and a tube diameter of 150 nm.

[0159] S1.2 Preparation of CdS / TiO2 heterojunction: Immerse the prepared TiO2 photoanode substrate material in a CdS / TiO2 heterojunction. 2+ and S 2- In the precursor solution, a uniformly distributed CdS nanoparticle layer is formed on the surface of the TiO2 substrate through a chemical deposition reaction, forming a CdS / TiO2 heterojunction;

[0160] Specifically, the chemical deposition reaction is carried out at a temperature of 60° C., the reaction time is 120 min, and the loading amount of the CdS nanoparticles is 10% by mass.

[0161] The method also includes spin coating a polyvinylidene fluoride film on the surface of the CdS / TiO2 heterojunction, with a film thickness of 5 μm.

[0162] S1.3 Photoanode modification: Graphene oxide dispersion was spin-coated on the CdS / TiO2 surface at a speed of 4000 rpm and a thickness of 1 μm, and then reduced at 250 °C to obtain the rGO-CdS / TiO2 composite electrode;

[0163] S2 photocathode preparation: Disperse the non-precious metal catalyst material in the carrier solution, apply it on the FTO glass conductive substrate and dry and solidify it;

[0164] Specifically, the non-precious metal catalyst material is polypyrrole or metal organic framework material, and the non-precious metal catalyst material is loaded on the conductive substrate by solution impregnation or spraying to form a catalyst film with a thickness of 300 μm.

[0165] In this embodiment, the non-noble metal catalyst material is a metal organic framework material, and the non-noble metal catalyst material is loaded on the FTO glass conductive substrate by a solution impregnation method.

[0166] S3 assembles a dual-chamber battery system: the photoanode and photocathode are placed in two separate chambers, separated by a proton exchange membrane;

[0167] The chambers of the dual-chamber battery system are made of heat-resistant glass or polytetrafluoroethylene material, and the proton exchange membrane is fixed between the chambers by hot pressing or bonding. In this embodiment, the proton exchange membrane is fixed between the chambers by hot pressing, and the temperature of the hot pressing method is 150°C and the pressure is 1.5MPa.

[0168] S4: adding electrolyte solution: injecting a solution containing 0.2 mol / L sodium sulfate or sodium carbonate into the chamber, and adjusting the pH value of the solution to 8;

[0169] S5 connects to the external circuit: connects the photoanode and the photocathode through a wire to form a closed loop, and sets a current collector.

[0170] The present invention also provides a CdS / TiO2-based photocatalytic fuel cell prepared by the above method.

[0171] The present invention also provides the application of the CdS / TiO2-based photocatalytic fuel cell prepared by the above method in treating organic wastewater.

[0172] Organic wastewater is wastewater containing dyes, antibiotics, phenolic compounds or pesticides, and the COD value of the organic wastewater is in the range of 1000 mg / L.

[0173] The application of CdS / TiO2-based photocatalytic fuel cells in the treatment of organic wastewater. The specific operation of organic wastewater treatment is as follows: injecting organic wastewater as an electrolyte solution into the cell chamber; starting the light source irradiation system to provide visible light irradiation to the surface of the photoanode with a wavelength range of 600nm; starting the reaction, the CdS / TiO2 heterojunction material on the surface of the photoanode absorbs visible light to generate photogenerated electrons and holes; the photogenerated electrons migrate from the CdS conduction band to the TiO2 conduction band and flow to the photocathode through the external circuit; the photogenerated holes remain in the CdS valence band and directly oxidize organic matter or react with water to generate active oxygen species; the catalyst on the surface of the photocathode receives electrons and converts H + Reduction to hydrogen; reactive oxygen species degrade organic matter and mineralize it into harmless substances such as CO2 and H2O; the generated electrical energy is collected through an external circuit.

[0174] In order to better illustrate the technical effects of the present invention, the following experimental verification is carried out.

[0175] Experimental Example 1: Battery Performance Test 1

[0176] 1.1 Experimental setup

[0177] Photoanode: CdS / TiO2 (CdS loading 1%):

[0178] Photocathode: metal organic framework material FTO glass (catalyst thickness 175μm);

[0179] Electrolyte: 0.15 M Na2SO4 (pH = 7);

[0180] Light source: 300W xenon lamp (λ≥420nm filter).

[0181] 1.2 Performance test:

[0182] Turn on the xenon lamp light source and preheat for 5 minutes to stabilize the light intensity;

[0183] Record open circuit voltage (OCV), short circuit current density (J s c);

[0184] Linear sweep voltammetry (LSV, scan rate: 5 mVs);

[0185] The current density was recorded as a function of time at a constant voltage of 0.4 V (lasting for 2 h).

[0186] 1.3 By-product testing:

[0187] The headspace of the photocathode chamber was sampled, and the H2 production was analyzed by gas chromatography (GC-2014, TCD detector);

[0188] Sampling was done in the anode chamber and COD was measured (potassium dichromate method) to evaluate the degradation rate of pollutants.

[0189] 1.4 Test data results:

[0190] Table 1 Battery electrochemical performance and pollutant degradation and hydrogen production performance data

[0191]

[0192] 1.5 Conclusion Analysis:

[0193] When the CdS loading is 1%, the CdS / TiO2 heterojunction shows the best performance: the open circuit voltage reaches 0.73V and the maximum power density is 0.49mWcm 2 , COD removal rate 94.2%, hydrogen production rate 12.3μmol / h·cm 2 When the loading increased to 5%, the performance decreased slightly but was still better than pure TiO2 (COD removal rate 32%).

[0194] The results show that CdS can significantly improve the separation efficiency of photogenerated carriers (the charge transfer impedance is reduced from 340Ω to 60Ω). In terms of pollutant degradation, the COD removal rate of the anode chamber wastewater reached more than 89%, indicating that the photocatalytic reaction can effectively degrade organic pollutants. At the same time, the hydrogen generation rate in the photocathode chamber reached 12.3μmol / h·cm 2 , which reflects the effective conversion of light energy into chemical energy and realizes the synergistic effect of photocatalytic degradation of organic matter and hydrogen production. That is, the CdS / TiO2-based photocatalytic fuel cell has excellent photoelectric performance and stable pollutant degradation and hydrogen production capabilities.

[0195] Experimental Example 2: CdS / TiO2 Photocatalytic Fuel Cell Performance Comparison Experiment

[0196] 2.1 Experimental Purpose:

[0197] Verify the expansion of the spectral response range of the CdS / TiO2 heterojunction pair (UV-visible light).

[0198] Compare the improvement effects of rGO modification on photogenerated carrier separation efficiency and stability.

[0199] Evaluate the performance and cost advantages of non-precious metal catalysts.

[0200] Verify the impact of the dual-chamber structure and proton exchange membrane on the overall efficiency of the battery.

[0201] 2.2 Experimental Design

[0202] 2.2.1 Experimental group and control group:

[0203]

[0204] 2.2.2 Experimental conditions:

[0205] Light source: 300W xenon lamp (equipped with filter, wavelength range: 300–600nm, simulating sunlight).

[0206] Electrolyte: 0.15 mol / L Na2SO4 (pH=7), as standard solution.

[0207] Test indicators:

[0208] Photoelectric performance: open circuit voltage (OCV), short circuit current density (Jsc), power density.

[0209] Degradation efficiency: the degradation rate of simulated organic wastewater (such as methylene blue solution, COD = 380 mg / L).

[0210] Hydrogen production rate: hydrogen production in the photocathode chamber (determined by gas chromatography).

[0211] Stability: Performance decay rate after 24 hours of continuous operation.

[0212] 2.3 Experimental steps:

[0213] 2.3.1 Photoanode preparation:

[0214] Experimental group: The rGO-CdS / TiO2 composite electrode was prepared according to the steps of Example 2.

[0215] Control group A: Preparation of pure TiO2 nanotube arrays (not loaded with CdS or rGO).

[0216] Control group B: Preparation of CdS / TiO2 heterojunction (without rGO modification).

[0217] 2.3.2 Photocathode preparation:

[0218] Experimental group and control group C: loaded with non-precious metal catalyst (such as ZIF-67).

[0219] Control groups A and B: loaded with Pt catalyst.

[0220] 2.3.3 Battery Assembly:

[0221] Experimental group and control group B and C: a double-chamber structure was used, separated by a proton exchange membrane.

[0222] Control group A: single-chamber structure (without proton exchange membrane).

[0223] 2.3.4 Performance testing:

[0224] Photoelectric performance test: record OCV, Jsc, and power density under xenon lamp irradiation.

[0225] Degradation efficiency test: inject methylene blue solution and measure the COD removal rate after 4 hours of reaction.

[0226] Hydrogen production rate test: The hydrogen production in the photocathode chamber was analyzed by gas chromatography.

[0227] Stability test: Repeat the above test after 24 hours of continuous operation to compare performance degradation.

[0228] 2.4 Experimental data:

[0229] Table 2 Battery performance comparison data

[0230]

[0231] 2.5 Conclusion Analysis:

[0232] 2.5.1 Spectral response expansion and optoelectronic performance advantages:

[0233] Experimental group vs. control group A:

[0234] The OCV (0.73 V) of the experimental group was 128% higher than that of the control group A (0.32 V), and the power density (0.49 mW / cm 2 ) is the control group A (0.12mW / cm 2 ) is 4.1 times.

[0235] Reason: The introduction of CdS significantly expanded the spectral response range (UV-visible light), while rGO modification further improved the electron migration efficiency and reduced the recombination of photogenerated carriers.

[0236] Experimental group vs control group B:

[0237] The power density of the experimental group (0.49mW / cm 2 ) than control group B (0.42mW / cm 2 ) is 16.7% higher.

[0238] Reason: The addition of rGO enhances the charge separation efficiency and suppresses the photocorrosion problem of CdS (see stability analysis for details).

[0239] 2.5.2 Degradation efficiency and wastewater treatment capacity:

[0240] Experimental group vs. control group A / B / C:

[0241] The COD removal rate of the experimental group (94.2%) was much higher than that of the control group A (32%), control group B (68%) and control group C (89.5%).

[0242] Reason: The CdS / TiO2 heterojunction provides more active sites, and the conductivity of rGO promotes the redox reaction of pollutants.

[0243] Control group B vs. control group C:

[0244] The COD removal rate of control group B (68%) was lower than that of control group C (89.5%), indicating that rGO modification significantly improved the degradation efficiency.

[0245] 2.5.3 Hydrogen production rate and economic efficiency:

[0246] Experimental group vs control group C:

[0247] The hydrogen production rate of the experimental group (12.3 μmol / h·cm 2 ) and control group C (11.8 μmol / h·cm 2 ) is close, but the cost is significantly reduced (ZIF-67 replaces Pt).

[0248] Reason: The non-precious metal catalyst (ZIF-67) significantly reduces material costs while ensuring catalytic activity.

[0249] Experimental group vs control group B:

[0250] The hydrogen production rate of the experimental group (12.3 μmol / h·cm 2 ) than control group B (10.8 μmol / h·cm 2 ) was 13.9% higher, further verifying the advantages of rGO modification.

[0251] 2.5.4 Stability and long-term operation capability:

[0252] Experimental group vs control group B:

[0253] The stability decay rate of the experimental group (<5%) was significantly lower than that of the control group B (20%).

[0254] Reason: The rGO coating inhibits the photocorrosion of CdS, while the PVDF membrane encapsulation further protects the photocatalyst.

[0255] Experimental group vs control group C:

[0256] The decay rate of the experimental group (<5%) was slightly lower than that of the control group C (8%), indicating that rGO modification had an additional improvement on stability.

[0257] 2.5.5 Double-chamber structure vs. single-chamber structure:

[0258] Experimental group vs. control group A:

[0259] The power density of the dual-chamber structure (experimental group) (0.49mW / cm 2 ) than the single-chamber structure (control group A, 0.12mW / cm 2) is 308% higher.

[0260] Reason: The proton exchange membrane separates the anode and cathode chambers, reducing the direct recombination of electrons and holes and improving energy conversion efficiency.

[0261] 2.6 Summary Conclusion:

[0262] Spectral response expansion: The CdS / TiO2 heterojunction significantly improves the visible light utilization efficiency (OCV of the experimental group is 128% higher than that of the control group A).

[0263] Charge separation efficiency: rGO modification reduced the charge transfer impedance (the power density of the experimental group was 16.7% higher than that of the control group B).

[0264] Enhanced stability: rGO / PVDF coating made the stability decay rate of the experimental group <5%, which was much better than the unmodified control group B (20%).

[0265] Economic optimization: The non-precious metal catalyst (ZIF-67) significantly reduced the cost of the experimental group, while the hydrogen production rate was close to that of the Pt catalyst.

[0266] Structural advantages: The power density of the dual-chamber structure (experimental group) is 4.1 times that of the single-chamber structure (control group A), verifying the rationality of the structural design.

[0267] This data shows that CdS / TiO2-based photocatalytic fuel cells are significantly superior to traditional solutions in terms of performance, stability and economy, and have broad prospects for industrial application.

[0268] Experimental Example 3: CdS / TiO2 Photocatalytic Fuel Cell Wastewater Treatment Test

[0269] 3.1 Target pollutant: simulated wastewater (COD = 380 mg / L) containing 50 mg / L methylene blue (MB).

[0270] 3.2 Operation process:

[0271] Wastewater was injected into the anode chamber, and 0.15M Na2CO3 was added to the photocathode chamber;

[0272] Visible light irradiation (λ = 420 ~ 600nm, light intensity 100mWcm 2 );

[0273] After 4 hours of reaction, COD and products were determined.

[0274] 3.3 Test data results:

[0275] Table 3 Treatment results of different pollutants

[0276]

[0277] 3.4 Conclusion Analysis:

[0278] Treatment of simulated wastewater containing 50 mg / L methylene blue under visible light irradiation:

[0279] Degradation efficiency: COD removal rate reaches 94.2% and TOC removal rate reaches 82.5% within 4 hours.

[0280] Energy recovery: 48.9 μmol of hydrogen and 1.46 mWh of electricity are generated simultaneously.

[0281] Broad-spectrum applicability: Under the same conditions, it can also efficiently degrade pollutants such as tetracycline (91.1%) and phenol (93.6%).

[0282] Safe by-products: Only harmless substances such as CO2 and H2O are detected after the reaction, and there is no risk of secondary pollution.

[0283] This demonstrates that the battery can efficiently mineralize organic pollutants into harmless substances such as CO2 and H2O, effectively purifying wastewater. Furthermore, a certain amount of hydrogen was collected in the photocathode chamber, further demonstrating that the system can simultaneously recycle hydrogen and electrical energy while treating wastewater, further improving the resource utilization and economic efficiency of the entire process and demonstrating its broad prospects for practical wastewater treatment applications.

[0284] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A method for constructing a CdS / TiO2-based photocatalytic fuel cell, characterized in that: The following steps are involved: S1 photoanode preparation: S1.1 Preparation of TiO2 photoanode substrate: Anodize a titanium sheet in a fluoride-containing electrolyte at a controlled voltage of 10-30 V for 10-60 min to form a TiO2 nanotube array, followed by sintering at 400-550°C for 2-4 hours. S1.2 Preparation of CdS / TiO2 heterojunction: Immerse the prepared TiO2 photoanode substrate material in a CdS / TiO2 heterojunction. 2+ and S 2- In the precursor solution, a uniformly distributed CdS nanoparticle layer is formed on the surface of the TiO2 substrate through a chemical deposition reaction, forming a CdS / TiO2 heterojunction; S1.3 Photoanode modification: Graphene oxide dispersion was spin-coated on the CdS / TiO2 surface at a speed of 2000-4000 rpm with a thickness of 0.1-1 μm, and then reduced at 150-250 °C to obtain the rGO-CdS / TiO2 composite electrode; S2 photocathode preparation: Disperse the non-precious metal catalyst material in the carrier solution, apply it on the FTO glass conductive substrate and dry and solidify it; S3 assembles a dual-chamber battery system: the photoanode and photocathode are placed in two separate chambers, separated by a proton exchange membrane; S4: adding electrolyte solution: injecting a solution containing 0.1-0.2 mol / L sodium sulfate or sodium carbonate into the chamber, and adjusting the pH value of the solution to 6-8; S5 connects to the external circuit: connects the photoanode and the photocathode through a wire to form a closed loop, and sets a current collector.

2. The method for constructing a CdS / TiO2-based photocatalytic fuel cell according to claim 1, characterized in that: The TiO2 substrate material in step S1.1 is an anatase TiO2 nanotube array, which is prepared on a conductive substrate by an anodic oxidation method, with a tube length of 50 to 200 μm and a tube diameter of 50 to 150 nm.

3. The method for constructing a CdS / TiO2-based photocatalytic fuel cell according to claim 1, characterized in that: The loading amount of the CdS nanoparticles in step S1.2 is 0.1% to 10% by mass, and the chemical deposition reaction is carried out at a temperature of 40 to 60° C. for 30 to 120 minutes.

4. The method for constructing a CdS / TiO2-based photocatalytic fuel cell according to claim 1, characterized in that: After step S1.2, the method further includes spin coating a polyvinylidene fluoride film on the surface of the CdS / TiO2 heterojunction, with a film thickness of 0.5 to 5 μm.

5. The method for constructing a CdS / TiO2-based photocatalytic fuel cell according to claim 1, characterized in that: In step S2, the non-precious metal catalyst material is polypyrrole or metal organic framework material, and the non-precious metal catalyst material is loaded on the conductive substrate by solution impregnation or spraying to form a catalyst film with a thickness of 50 to 300 μm.

6. The method for constructing a CdS / TiO2-based photocatalytic fuel cell according to claim 1, characterized in that: The chambers of the dual-chamber battery system in step S3 are made of heat-resistant glass or polytetrafluoroethylene material, and the proton exchange membrane is fixed between the chambers by hot pressing or bonding. The temperature of the hot pressing method is 100-150° C. and the pressure is 0.5-1.5 MPa.

7. A CdS / TiO2-based photocatalytic fuel cell prepared according to the method of any one of claims 1 to 6.

8. Use of the CdS / TiO2-based photocatalytic fuel cell according to claim 7 in treating organic wastewater.

9. The use according to claim 8, characterized in that The organic wastewater is wastewater containing dyes, antibiotics, phenolic compounds or pesticides, and the COD value of the organic wastewater ranges from 50 to 1000 mg / L.

10. The use of the CdS / TiO2-based photocatalytic fuel cell in treating organic wastewater according to claim 9, characterized in that: The specific operation of the organic wastewater treatment is: Organic wastewater is injected into the battery chamber as an electrolyte solution; the light source irradiation system is started to provide visible light irradiation to the surface of the photoanode with a wavelength range of 420 to 600 nm; the reaction begins, and the CdS / TiO2 heterojunction material on the surface of the photoanode absorbs visible light to generate photogenerated electrons and holes; the photogenerated electrons migrate from the CdS conduction band to the TiO2 conduction band and flow to the photocathode through an external circuit; the photogenerated holes remain in the CdS valence band and directly oxidize organic matter or react with water to generate active oxygen species; the catalyst on the surface of the photocathode receives electrons and converts H + Reduction to hydrogen; reactive oxygen species degrade organic matter and mineralize it into harmless substances such as CO2 and H2O; the generated electrical energy is collected through an external circuit.

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