Preparation of biOX by lattice desalting method and application of the same in electrocatalytic production of halogen
BiOX nanosheets were prepared by lattice desalination, which solved the problem of high power consumption in the production of free chlorine and achieved efficient and stable electrocatalytic production of free halogens, suitable for large-scale industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTHERN UNIVERSITY OF SCIENCE AND TECHNOLOGY
- Filing Date
- 2023-04-17
- Publication Date
- 2026-05-12
AI Technical Summary
Existing free chlorine production processes consume a lot of electricity, making it difficult to meet energy conservation and environmental protection requirements, and there is a lack of stable electrode materials for highly selective electrocatalytic production of free chlorine.
BiOX nanosheets were prepared by lattice desalting. In situ phase transformation of the bismuth-based layered material MaBibOcXd in the electrolyte was achieved by electrocatalysis. The resulting fluffy sheet-like BiOX nanosheets were generated by electrocatalysis of the layered material MaBibOcXd in the electrolyte. By utilizing its layered structure and co-occupancy characteristics, the nanosheets were efficiently and stably electrocatalyzed to produce free halogens in the electrolyte.
It achieves efficient and stable electrocatalytic production of free halogens, reduces resource consumption and energy consumption, and is suitable for large-scale industrial production.
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Figure CN116479441B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electrocatalysis, and in particular to the preparation of BiOX by lattice desalting and its application in the electrocatalytic production of halogen elements. Background Technology
[0002] Free chlorine refers to chlorine in the form of hypochlorous acid (HClO) and hypochlorite ions (ClO). - Free chlorine exists in both its active and dissolved forms (Cl2) and is widely used in daily life and many important industrial processes, such as disinfectants, organic polymer synthesis, pharmaceutical production, and wastewater treatment. Industrial production of free chlorine primarily relies on the electrolysis of sodium chloride. Research data shows that the global annual production of free chlorine exceeds 75 million tons, with each ton of chlorine consuming approximately 2200-2600 kWh of electricity. This means that current free chlorine production methods are ill-suited to the energy-saving and environmentally friendly requirements of industrial sodium chloride production. Therefore, it is necessary to improve the electrolysis process through appropriate technological methods to reduce resource consumption and energy consumption.
[0003] Seawater is an abundant and sustainable natural brine source, characterized by its concentrated environment and vast reserves; simultaneously, the abundant sunshine near the coast means that using solar energy as the primary power source is highly feasible. Therefore, a photovoltaic-coupled electrocatalytic system using seawater as the electrolyte feedstock is an ideal, economical, and convenient method for producing active free chlorine. However, to address the resource and energy consumption limitations, a key challenge for this system is providing highly selective and stable electrode materials for the electrocatalytic production of free chlorine. Summary of the Invention
[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a lattice desalting method for the preparation of BiOX and its application in the electrocatalytic production of halogen elements.
[0005] A first aspect of this application provides a method for preparing BiOX using lattice desalting, comprising the following steps:
[0006] Electrocatalytic bismuth-based substrate M in electrolyte a Bi b O c X d Topological lattice desalination and in-situ phase transformation generate fluffy, sheet-like BiOX nanosheets;
[0007] Wherein, M is at least one element among alkali metals and alkaline earth metals.
[0008] The preparation method according to the embodiments of this application has at least the following beneficial effects:
[0009] The precursor material involved in the preparation method is a bismuth-based morphological material M in which alkali metal / alkaline earth metal and bismuth elements co-occupy the site. a Bi b O c X d Due to its layered structure and the co-occupancy of bismuth with alkali / alkaline earth metals, BiOX nanosheets undergo a lattice desalination phase transformation reaction under charging conditions. Specifically, the material interacts with the electrolyte, releasing alkali or alkaline earth metal ions from the lattice, resulting in a phase transition and growth into fluffy, sheet-like BiOX nanosheets. These fluffy, sheet-like BiOX nanosheets possess fully exposed active interfaces, and the unsaturated halogen vacancies in the coordination lattice serve as active sites for the oxidation of free halogens, exhibiting electrocatalytic production of free halogens in a liquid phase containing halide ions. Based on the self-oxidation of lattice halogens and the migration and replenishment of ions in the liquid phase, using fluffy, sheet-like BiOX nanosheets for electrocatalytic production of free halogens in halide-containing liquid phases can achieve highly efficient and stable electrocatalytic production of free halogens, allowing for recycling.
[0010] Meanwhile, the preparation method is simple, the raw materials are readily available and inexpensive, and it is easy to implement, making it suitable for large-scale industrial production.
[0011] Bismuth-based morphological material M a Bi b O c X d The following conditions must be met: a′+2a″+3b=2c+d, where a′ is the relative amount of alkali metals in M, a″ is the relative amount of alkaline earth metals in M, a′+a″=a, and neither a′ nor a″ is negative.
[0012] In some embodiments of this application, a is 1 to 2.
[0013] In some embodiments of this application, b is 1 to 3.
[0014] In some embodiments of this application, c is 1 to 4.
[0015] In some embodiments of this application, d is 1 to 2.
[0016] In some embodiments of this application, c is 1 to 4, and d is 1 to 2.
[0017] In some embodiments of this application, a is 1 to 2, b is 1 to 3, c is 1 to 4, and d is 1 to 2.
[0018] In some embodiments of this application, the alkali metal element of M is selected from at least one of Li and Na.
[0019] In some embodiments of this application, the alkaline earth metal element of M is selected from at least one of Ca and Ba.
[0020] In some embodiments of this application, M is selected from at least one of Li, Na, Ca, and Ba.
[0021] In some embodiments of this application, M a Bi b O c X d The halogen X in BiOX can be the same as or different from the halogen X in BiOX.
[0022] In some embodiments of this application, the electrolyte is an electrolyte containing halogen X ions, which contains ions of the same halogen element X as those in the BiOX nanosheets.
[0023] In some embodiments of this application, the halogen in BiOX and the anionic halogen in the electrolyte are the same.
[0024] In some embodiments of this application, M a Bi b O c X d The halogen X in the electrolyte is the same as the halogen in BiOX and the anionic halogen in the electrolyte.
[0025] In some embodiments of this application, bismuth-based morphological material M a Bi b O c X d Selected from NaBi3O4Cl2, LiBi3O4Cl2, Ca 1.25 Bi 1.5 At least one of O2Cl3, BaBiO2Cl, NaBi3O4Br2, NaBi3O4I2, etc.
[0026] In some embodiments of this application, bismuth-based morphological material M a Bi b O c X d For M a Bi b O c Cl d .
[0027] In some embodiments of this application, the electrocatalytic bismuth-based substrate material M a Bi b O c X d The operating voltage for topological lattice desalination is 10–25 V vs. RHE.
[0028] In some embodiments of this application, the electrocatalytic bismuth-based substrate material M a Bi b O c X d The topological lattice desalination is performed by charging the power supply components to carry out the lattice desalination phase transformation reaction.
[0029] In some embodiments of this application, the power supply component includes a photovoltaic panel. In the above process, by utilizing the photovoltaic panel, solar radiation energy is directly converted into electrical energy through the photoelectric effect to drive the lattice desalination phase transformation of the electrocatalytic bismuth-based substrate material by absorbing sunlight. The entire process does not require separate consumption of electrical energy, and utilizes sustainable and clean energy such as sunlight, making the entire process cleaner and more environmentally friendly.
[0030] It is understandable that the lattice desalination phase transformation reaction does not depend on the photovoltaic panels in the power supply components. Therefore, the power supply components can also include other types of power sources, such as conventional DC power sources.
[0031] In some embodiments of this application, the output voltage of the photovoltaic panel is 10-25V vs. RHE.
[0032] In some embodiments of the present invention, the voltage of the photovoltaic panel is at least one of 5V, 10V, 13V, 20V, 25V vs. RHE.
[0033] In some embodiments of the present invention, the working electrode serves as the cathode for the electrocatalytic reaction.
[0034] In some embodiments of the present invention, the counter electrode serves as the anode for the electrocatalytic reaction.
[0035] In some embodiments of this application, the electrocatalytic bismuth-based substrate material M a Bi b O c X d The desalination time for topological lattice is 1 to 16 hours.
[0036] In some embodiments of this application, the electrocatalytic bismuth-based substrate material M a Bi b O c X d The desalination time for topological lattice is 4–12 h.
[0037] In some embodiments of this application, the electrolyte contains ions of the same halogen element X as those in the BiOX nanosheets. The precursor material interacts with the halogen ions in the electrolyte, replacing the halogen ions in the precursor lattice with those in the electrolyte, releasing alkali metal or alkaline earth metal ions from the lattice, undergoing a phase transition, and growing into fluffy, sheet-like BiOX nanosheets.
[0038] In some embodiments of this application, BiOCl is prepared by lattice desalting, and bismuth-based substrate M is electrocatalyzed in a chlorine-containing electrolyte. a Bi b O c X d Topological lattice desalination and in-situ phase transformation generate fluffy, sheet-like BiOCl nanosheets.
[0039] In some embodiments of this application, the chlorine-containing electrolyte includes a salt containing the same chlorine-containing halide ion, such as at least one of NaCl and KCl.
[0040] In some embodiments of this application, the chlorine-containing electrolyte includes at least one of a salt solution or an ionic liquid containing chloride ions.
[0041] In some embodiments of this application, the chlorine-containing electrolyte is at least one of a natural or artificial salt solution or ionic liquid containing chloride ions.
[0042] In some embodiments of this application, the chlorine-containing electrolyte is at least one of a sodium chloride salt solution, a potassium chloride salt solution, or seawater.
[0043] In some embodiments of this application, the electrocatalytic bismuth-based substrate material M a Bi b O c X d Topological lattice desalination includes the following steps:
[0044] An electrode slurry containing bismuth-based substrate material is used to form the working electrode of an electrocatalytic system.
[0045] After the electrocatalytic system starts working, bismuth-based crystalline material M forms on the working electrode. a Bi b O c X d Topological lattice desalination leads to in-situ phase transformation, generating fluffy, sheet-like BiOX nanosheets.
[0046] In some embodiments of this application, the electrocatalytic bismuth-based substrate material M a Bi b O c Cl d Topological lattice desalination includes the following steps:
[0047] An electrode slurry containing bismuth-based substrate material is used to form the working electrode of an electrocatalytic system.
[0048] After the electrocatalytic system starts working, bismuth-based crystalline material M forms on the working electrode. a Bi b Oc X d Topological lattice desalination leads to in-situ phase transformation, generating fluffy, sheet-like BiOCl nanosheets.
[0049] In some embodiments of this application, the electrocatalytic bismuth-based substrate material M a Bi b O c Cl d Topological lattice desalination includes the following steps:
[0050] An electrode slurry containing bismuth-based substrate material is used to form the working electrode of an electrocatalytic system.
[0051] After the electrocatalytic system starts working, bismuth-based crystalline material M forms on the working electrode. a Bi b O c Cl d Topological lattice desalination leads to in-situ phase transformation, generating fluffy, sheet-like BiOCl nanosheets.
[0052] In some embodiments of this application, the electrode paste includes a bismuth-based crystalline material and a solvent. In some embodiments, the electrode paste further includes at least one of a conductive agent and a binder. In some embodiments, the conductive agent includes, but is not limited to, at least one of graphite, acetylene black, carbon black, carbon nanotubes, and carbon fibers; the binder includes, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyurethane (PU), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). In some embodiments, the solvent includes, but is not limited to, at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and tetrahydrofuran.
[0053] In some embodiments of this application, the mass ratio of bismuth-based matrix material, conductive agent, and binder in the electrode slurry is (50-99):(0.1-20):(0.1-20).
[0054] In some embodiments of this application, the mass ratio of bismuth-based matrix material, conductive agent, and binder in the electrode slurry is (60-95):(0.2-15):(0.2-15).
[0055] In some embodiments of this application, the electrocatalytic system is a two-electrode system, including a working electrode and a counter electrode.
[0056] In some embodiments of this application, the material of the counter electrode of the electrocatalytic system is selected from inert noble metals (such as at least one of platinum and titanium), non-metals (such as carbon materials, including at least one of graphite and activated carbon), etc.
[0057] In some embodiments of this application, the counter electrode of the electrocatalytic system is selected from at least one of platinum wire, titanium wire, platinum sheet, titanium sheet, platinum plate, titanium plate, platinum mesh, titanium mesh, carbon rod, carbon paper, etc.
[0058] In some embodiments of this application, the surface area ratio of the working electrode to the counter electrode of the electrocatalytic system is (1-5):1.
[0059] A second aspect of this application provides a BiOX nanosheet prepared using any of the aforementioned preparation methods.
[0060] BiOX nanosheets are open, fluffy, layered materials with a lattice arrangement of chlorine atoms, and are a type of bismuth halide nanosheets.
[0061] In some embodiments of this application, BiOX nanosheets are open, fluffy, sheet-like layered structures with lattice halogen atom arrangement, and are a type of bismuth halide nanosheet.
[0062] In some embodiments of this application, BiOCl nanosheets are open, fluffy, sheet-like layered structures with lattice chlorine atom arrangement, and are a type of bismuth oxychloride nanosheets.
[0063] A third aspect of this application provides an electrode containing an active material, the active material comprising the aforementioned BiOCl nanosheets or a bismuth-based substrate material M. a Bi b O c X d In this electrode, BiOX nanosheets serve as the active material or bismuth-based substrate material. a Bi b O c X d As a reaction raw material on the electrode.
[0064] Bismuth-based morphological material M a Bi b O c X d The following conditions must be met: a′+2a″+3b=2c+d, where a′ is the relative amount of alkali metals in M, a″ is the relative amount of alkaline earth metals in M, a′+a″=a, and neither a′ nor a″ is negative.
[0065] In some embodiments of this application, a is 1 to 2.
[0066] In some embodiments of this application, b is 1 to 3.
[0067] In some embodiments of this application, c is 1 to 4.
[0068] In some embodiments of this application, d is 1 to 2.
[0069] In some embodiments of this application, c is 1 to 4, and d is 1 to 2.
[0070] In some embodiments of this application, a is 1 to 2, b is 1 to 3, c is 1 to 4, and d is 1 to 2.
[0071] In some embodiments of this application, the alkali metal element of M is selected from at least one of Li and Na.
[0072] In some embodiments of this application, the alkaline earth metal element of M is selected from at least one of Ca and Ba.
[0073] In some embodiments of this application, M is selected from at least one of Li, Na, Ca, and Ba.
[0074] In some embodiments of this application, M a Bi b O c X d The halogen X in BiOX can be the same as or different from the halogen in BiOX.
[0075] In some embodiments of this application, the electrolyte is an electrolyte containing halogen X ions, which contains ions of the same halogen element X as those in the BiOX nanosheets.
[0076] In some embodiments of this application, the halogen in BiOX and the anionic halogen in the electrolyte are the same.
[0077] In some embodiments of this application, M a Bi b O c X d The halogen X in the electrolyte is the same as the halogen in BiOX and the anionic halogen in the electrolyte.
[0078] In some embodiments of this application, bismuth-based morphological material M a Bi b O c X d Selected from NaBi3O4Cl2, LiBi3O4Cl2, Ca 1.25 Bi 1.5 At least one of O2Cl3, BaBiO2Cl, NaBi3O4Br2, NaBi3O4I2, etc.
[0079] In some embodiments of this application, M a Bi b O c X d For Ma Bi b O c Cl d .
[0080] In some embodiments of this application, the electrode layer further includes at least one of a conductive agent and a binder. In some embodiments, the conductive agent includes, but is not limited to, at least one of graphite, acetylene black, carbon black, carbon nanotubes, and carbon fibers, and the binder includes, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyurethane (PU), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).
[0081] In some embodiments of this application, the mass ratio of bismuth-based morphological material, conductive agent, and binder in the electrode layer is (50-99):(0.1-20):(0.1-20).
[0082] In some embodiments of this application, the mass ratio of bismuth-based morphological material, conductive agent, and binder in the electrode layer is (60-95):(0.2-15):(0.2-15).
[0083] A fourth aspect of this application provides an electrocatalytic system including a working electrode comprising the aforementioned electrode.
[0084] In some embodiments of this application, the electrocatalytic system is a photovoltaic-coupled electrocatalytic system.
[0085] In some embodiments of this application, the electrocatalytic system includes a power supply component.
[0086] In some embodiments of this application, the power supply component includes a photovoltaic panel.
[0087] In some embodiments of this application, the electrocatalytic system further includes a counter electrode.
[0088] In some embodiments of this application, the electrocatalytic system includes a power supply component, a working electrode, and a counter electrode. The working electrode is the aforementioned electrode, which has an electrode layer comprising BiOX nanosheets or a bismuth-based substrate material M. a Bi b O c X d .
[0089] In some embodiments of this application, the electrocatalytic system is a photovoltaic coupled electrocatalytic system, including a power supply component, a working electrode, a counter electrode, and an electrolyte, wherein the power supply component includes a photovoltaic panel.
[0090] A fifth aspect of this application provides a method for electrocatalytic production of halogen elements, wherein the method employs the aforementioned electrocatalytic system to catalyze the production of halogen elements from an electrolyte.
[0091] In some embodiments of this application, in the method for electrocatalytic production of halogen elements, the electrodes of the electrocatalytic system for electrocatalytic production of halogen elements include BiOX nanosheets or bismuth-based substrate material M. a Bi b O c X d .
[0092] In some embodiments of this application, the method for electrocatalytic production of halogen elements is a method for electrocatalytic production of chlorine.
[0093] In some embodiments of this application, the electrolyte includes a chlorine-containing salt, such as at least one of NaCl and KCl.
[0094] In some embodiments of this application, the electrolyte includes at least one of a chlorine-containing salt solution or an ionic liquid.
[0095] In some embodiments of this application, the electrolyte is at least one of a natural or artificial salt solution or ionic liquid containing chloride ions.
[0096] In some embodiments of this application, the electrolyte is at least one of NaCl solution, KCl solution, and seawater.
[0097] In some embodiments of this application, the electrocatalytic system is a photovoltaic-coupled electrocatalytic system.
[0098] In some embodiments of this application, the electrocatalytic system includes a power supply component, which includes a photovoltaic panel.
[0099] In some embodiments of this application, the electrocatalytic chlorine production operation time is from 9:00 to 16:00 on sunny days. In some other embodiments, the electrocatalytic chlorine production operation time is from 11:00 to 15:00 on sunny days.
[0100] A sixth aspect of this application provides the application of any one of the aforementioned BiOX nanosheets, the aforementioned electrodes, or the aforementioned electrocatalytic system in photovoltaic-coupled electrocatalytic production of halogen elements.
[0101] Among them, photovoltaic coupled electrocatalytic halogen production refers to the use of photovoltaic principles, with photovoltaic panels as the energy supply, to catalyze the electrolysis of a halogen-containing electrolyte. In this process, halogen ions are oxidized into free halogens to produce halogen elements.
[0102] In some embodiments of this application, photovoltaic-coupled electrocatalytic halogen production is photovoltaic-coupled electrocatalytic chlorine production. Utilizing the photovoltaic principle, a photovoltaic panel is used as the energy supply to catalyze the electrolysis of a chlorine-containing electrolyte. During this process, chloride ions are oxidized to free chlorine to achieve chlorine production.
[0103] In summary, the fluffy, sheet-like BiOCl nanosheets provided in this application have fully exposed active interfaces, and the unsaturated vacancies in the coordination lattice are active sites for the oxidation of free chlorine. They exhibit electrocatalytic production of free chlorine molecules in water containing chloride ions. Based on the self-oxidation of lattice chlorine and the migration and replenishment of chloride ions in the water, using the fluffy, sheet-like BiOCl nanosheet material in a dual-electrode photovoltaic-coupled electrocatalytic system can achieve highly efficient and stable electrocatalytic production of free chlorine, and can be recycled.
[0104] The dual-electrode photovoltaic-coupled electrocatalytic system mainly comprises a working electrode and a counter electrode made of fluffy, sheet-like BiOCl nanosheets. This dual-electrode photovoltaic-coupled electrocatalytic system can be widely used in the fields of free chlorination from seawater and the utilization of seawater resources, and it is recyclable. Moreover, the dual-electrode photovoltaic-coupled electrocatalytic system can include the aforementioned electrocatalytic seawater free chlorination system, and can be widely used in fields such as free chlorination from seawater and the utilization of seawater resources, thus having broad application prospects.
[0105] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0106] Figure 1 The images show scanning electron microscope (SEM) images of the precursor material NaBi3O4Cl2 and the fluffy, sheet-like BiOCl nanosheets obtained by electrocatalytic desodium conversion in this embodiment of the invention.
[0107] Figure 2 The image shows the in-situ X-ray test results of the phase transition process of the precursor material NaBi3O4Cl2, which is electrocatalytically desodiumed and converted into fluffy BiOCl nanosheets in an embodiment of the present invention.
[0108] Figure 3 This is a schematic diagram of the structure and operation of the dual-electrode photovoltaic coupled electrocatalytic system in an embodiment of the present invention.
[0109] Figure 4 The figure shows the performance results of the electrocatalytic production of free chlorine from seawater using BiOCl nanosheets synthesized by ordinary hydrothermal methods and BiOCl nanosheets converted into fluffy flakes by electrocatalytic desodiumization in this invention as the working electrode material in the dual-electrode photovoltaic coupling system of this invention.
[0110] Figure 5The graph shows the cycle performance results of the dual-electrode photovoltaic coupling system for electrocatalytic production of free chlorine from seawater in an embodiment of the present invention. Detailed Implementation
[0111] The following will clearly and completely describe the concept and technical effects of this application in conjunction with embodiments, so as to fully understand the purpose, features and effects of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application.
[0112] The embodiments of this application are described in detail below. The described embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0113] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0114] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.
[0115] In the description of this application, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0116] Example 1
[0117] This embodiment discloses an electrode material, which is a fluffy, sheet-like BiOCl nanosheet. The specific preparation process is as follows:
[0118] Weigh 1.96g of precursor material NaBi3O4Cl2 and 0.245g of acetylene black, mix them evenly, and add 0.245mL of PVDF solution (0.02g PVDF / 1mL NMP) dropwise to mix evenly and form an electrode slurry.
[0119] The electrode paste described above is poured into a mold, dried, and shaped to form a sample with an area of 25 cm². 2 A square working electrode, and at the same time prepare a square working electrode of the same area (25cm²). 2 The electrode is a titanium plate, and seawater is used as the electrolyte.
[0120] refer to Figure 3 This is a schematic diagram of the structure of the dual-electrode photovoltaic-coupled electrocatalytic system in an embodiment of this application. The dual-electrode photovoltaic-coupled electrocatalytic system includes a power source and an electrolytic cell. The power source includes a photovoltaic panel, and the electrolytic cell includes an electrolyte, a working electrode, and a counter electrode. The system is ultimately assembled to form a dual-electrode photovoltaic-coupled electrocatalytic system. Based on this principle, an electrocatalytic reaction is performed, transforming the precursor material NaBi3O4Cl2 of the working electrode into fluffy, sheet-like BiOCl nanosheets through a sodium-removing phase. During the electrocatalytic reaction, the working voltage of the photovoltaic panel was 10V vs. RHE, the reaction time was 4 hours × 2 days, the location was the rooftop of the 7th floor of the North Building, College of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong Province, China, and the time was September 16-17, 2022, from 11:00 to 15:00.
[0121] refer to Figure 1 The images show the microstructure of the precursor material and the product on the working electrode after two days of reaction, as determined by scanning electron microscopy (SEM) at a working voltage of 5 kV. The images reveal that the precursor material, NaBi3O4Cl2, is a tightly packed thin nanosheet. However, during the electrocatalytic reaction in the electrolytic cell, a topological lattice desalination phase transformation reaction occurs. This process involves the precursor material interacting with chloride ions in the electrolyte solution, releasing alkali metal or alkaline earth metal ions from the lattice, resulting in a phase transition and the growth of a loose, sheet-like BiOCl nanosheet structure. (Reference) Figure 2 This image shows the in-situ X-ray diffraction results of the phase transition process of the precursor material NaBi3O4Cl2, which undergoes electrocatalytic desodiumification to transform into fluffy, sheet-like BiOCl nanosheets. X-ray testing conditions: test angle range 5–60°, step speed 10° / min, test voltage 1.4V vs. SCE (three-electrode system). Figure 2 The results showed that during the charging process of the photovoltaic coupled electrocatalytic system, the diffraction peak of the NaBi3O4Cl2 phase continuously weakened, while the diffraction peak of the BiOCl phase weakened with the oxidation process and strengthened with the reduction process, and fluffy sheet-like BiOCl nanosheets were continuously generated.
[0122] This embodiment also discloses a method for in-situ electrolysis of seawater to generate free chlorine using the fluffy, sheet-like BiOCl nanosheet working electrode prepared above. The specific process is as follows:
[0123] The working electrode, which has transformed into a fluffy sheet-like BiOCl nanosheet after two days of operation in the aforementioned steps, was selected as the working electrode for electrolysis yield, still with an area of 25 cm². 2 A titanium plate was used as the counter electrode. The existing dual-electrode photovoltaic-coupled electrocatalytic system was selected, powered by a 10V vs. RHE photovoltaic panel, to continue the electrocatalytic reaction. Unlike previous experiments, this part of the electrocatalytic reaction mainly focused on the electrocatalytic production of free chlorine from seawater. Location: Rooftop, 7th Floor, North Building, School of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong Province, China; Time: September 18, 2022, 11:00-15:00.
[0124] Example 2
[0125] This embodiment discloses an electrode material, which is a fluffy, sheet-like BiOCl nanosheet. The specific preparation process is as follows:
[0126] Weigh 1.92g of precursor material LiBi3O4Cl2 and 0.240g of acetylene black, mix them evenly, and add 0.240mL of PVDF solution (0.02g PVDF / 1mL NMP) dropwise to mix evenly and form an electrode slurry.
[0127] The electrode paste described above is poured into a mold, dried, and shaped to form a sample with an area of 25 cm². 2 The working electrode is a square sheet, and the counter electrode differs from that in Example 1, with an area of 25 cm². 2 The carbon cloth was assembled into a dual-electrode photovoltaic-coupled electrocatalytic system in a manner similar to that in Example 1, and the electrocatalytic delithiation phase was converted into fluffy sheet-like BiOCl nanosheets. During the electrocatalytic reaction, the operating voltage of the photovoltaic panel was 13V vs. RHE, the reaction time was 4h×2d, the location was the rooftop of the 7th floor of the North Building of the School of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong Province, China, and the time was from 11:00 to 15:00 on October 11-12, 2022.
[0128] This embodiment also discloses a method for in-situ electrocatalytic generation of free chlorine from seawater using the above-prepared fluffy BiOCl nanosheet working electrode. The specific process is as follows:
[0129] The working electrode, which had transformed into fluffy sheet-like BiOCl nanosheets after two days of operation in the aforementioned steps, was selected as the working electrode for electrocatalytic chlorination, and the electrode was still positioned at 25 cm⁻¹. 2 Using carbon cloth as the counter electrode, the existing dual-electrode photovoltaic-coupled electrocatalytic system was selected and powered by a 10V vs. RHE photovoltaic panel to continue the electrocatalytic reaction, producing free chlorine from seawater. Location: Rooftop, 7th Floor, North Building, School of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong Province, China; Time: October 13, 2022, 11:00-15:00.
[0130] Example 3
[0131] This embodiment discloses an electrode material, which is a fluffy, sheet-like BiOCl nanosheet. The specific preparation process is as follows:
[0132] Weigh 2.18g of precursor material NaBi3O4Br2 and 0.272g of acetylene black, mix them evenly, and add 0.272mL of PVDF solution (0.02g PVDF / 1mL NMP) dropwise to mix evenly and form an electrode slurry.
[0133] The electrode paste described above is poured into a mold, dried, and shaped to form a sample with an area of 25 cm². 2 The working electrode is a square sheet, but the counter electrode differs from that in Example 1, having an area of 16.5 cm². 2 Carbon rods were assembled into a dual-electrode photovoltaic-coupled electrocatalytic system in a manner similar to that in Example 1. Electrocatalytic desodium phase conversion occurred, with the precursor material on the working electrode interacting with chloride ions in the seawater electrolyte, releasing sodium ions from the lattice. The original Br was also exchanged for Cl from the seawater, ultimately forming fluffy, sheet-like BiOCl nanosheets. During the electrocatalytic reaction, the photovoltaic panel operated at 20V vs. RHE, the reaction time was 4 hours × 1 day, the location was the rooftop of the 7th floor of the North Building, College of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong Province, China, and the time was November 19, 2022, from 11:00 AM to 3:00 PM.
[0134] This embodiment also discloses a method for in-situ electrocatalytic generation of free chlorine from seawater using the above-prepared fluffy BiOCl nanosheet working electrode. The specific process is as follows:
[0135] The working electrode, which had transformed into fluffy sheet-like BiOCl nanosheets after one day of operation in the aforementioned steps, was selected as the working electrode for electrocatalytic chlorination, and its area remained 16.5 cm². 2 Using a carbon rod as the counter electrode, the existing dual-electrode photovoltaic-coupled electrocatalytic system was selected and powered by a 20V vs. RHE photovoltaic panel to continue the electrocatalytic reaction, producing free chlorine from seawater. Location: Rooftop, 7th Floor, North Building, School of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong Province, China; Time: November 20, 2022, 11:00-15:00.
[0136] Experimental Example: Free Chlorine Yield Test
[0137] The testing method is as follows:
[0138] Seawater containing free chlorine was analyzed using N,N-diethyl-1,4-phenylenediamine spectrophotometry after 4 hours of electrocatalysis with fluffy BiOCl nanosheets in the dual-electrode photovoltaic-coupled electrocatalytic systems of Examples 1-3 and Comparative Example 1. The results are shown in Table 1 below.
[0139] Table 1. Free chlorine production in different embodiments
[0140] Example Total free chlorine production (mg / L) Example 1 138 Example 2 129 Example 3 110
[0141] The only difference between Comparative Example 1 and Example 1 is that the BiOCl nanosheets were changed from fluffy sheet-like to BiOCl nanosheets obtained by hydrothermal synthesis, omitting the previous preparation of fluffy sheet-like BiOCl nanosheets. The specific steps of the hydrothermal synthesis method are as follows:
[0142] 1.2 mmol of bismuth nitrate and 7.5 mmol of sodium chloride were added to 20 mL of ethylene glycol and stirred for 30 min. The solution was then transferred to a polytetrafluoroethylene liner for hydrothermal reaction at 160 °C for 6.5 h. After cooling, the solution was centrifuged, washed, and dried to obtain the final product. Electron microscopy revealed that the BiOCl nanosheets were rose-shaped, which was significantly different from the fluffy sheet-like structure of the sample in Example 1.
[0143] The results of electrocatalytic chlorination of seawater in Example 1 and Comparative Example 1 are as follows: Figure 4 As shown in Table 1, the dual-electrode photovoltaic-coupled electrocatalytic system based on fluffy BiOCl nanosheets exhibits highly efficient electrocatalytic production of free chlorine from seawater, which is significantly better than that of BiOCl nanosheets synthesized by conventional hydrothermal methods.
[0144] Meanwhile, the chlorine production performance of the dual-electrode photovoltaic-coupled electrocatalytic system in Example 1, where the working electrode had been transformed into fluffy sheet-like BiOCl nanosheets, was repeatedly tested, and the results are as follows: Figure 5 As shown in the figure, the chlorine production efficiency showed a certain downward trend in repeated experiments of electrocatalytic chlorine production, which may be due to the partial wear and tear of the electrode material during recycling.
[0145] Example 4
[0146] This embodiment provides a method for electrocatalytically generating free chlorine from seawater. The difference from Example 3 is that the precursor material is replaced with BaBiO2Cl when preparing BiOCl nanosheets.
[0147] Example 5
[0148] This embodiment provides a method for electrocatalytically generating free chlorine from seawater. The difference from Example 3 is that the precursor material is replaced with NaBi3O4I2 when preparing BiOCl nanosheets.
[0149] Example 6
[0150] This embodiment provides a method for electrocatalytically generating free chlorine from seawater. The difference from Example 3 is that, in the preparation of BiOCl nanosheets, the precursor material is replaced with Ca. 1.25 Bi 1.5 O2Cl3.
[0151] Example 7
[0152] This embodiment provides a method for electrocatalytically generating free chlorine. The difference from Embodiment 2 is that the electrolyte is replaced with a saturated saline solution during the preparation of BiOCl nanosheets and chlorine generation.
[0153] The BiOCl nanosheets obtained in Examples 4-7 above have a similar fluffy sheet-like structure to those in Example 1, and can achieve a similar chlorine production effect as in Examples 1-3 during the continued generation of free chlorine.
[0154] The present application has been described in detail above with reference to the embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application. Furthermore, unless otherwise specified, the embodiments and features in the embodiments of the present application can be combined with each other.
Claims
1. A method for electrocatalytic production of halogen elements, characterized in that, An electrocatalytic system is used to electrocatalyze the production of halogen elements from an electrolyte. The electrocatalytic system includes a working electrode and a counter electrode. The working electrode contains an active material, which includes BiOX nanosheets. The BiOX nanosheets are prepared using a lattice desalting method. The lattice desalting method involves electrocatalyzing a bismuth-based crystalline material M in the electrolyte. a Bi b O c X d Topological lattice desalting and in-situ phase transformation generate fluffy, sheet-like BiOX nanosheets. The electrolyte is a halogen X ion-containing electrolyte, which contains ions of the same halogen element X as those in the BiOX nanosheets; wherein M is at least one element selected from alkali metals and alkaline earth metals, and the bismuth-based crystalline material M... a Bi b O c X d satisfy a′ +2 a′′ +3 b =2 c + d ,in, a′ This represents the relative amount of alkali metals in M. a′′ Let M be the relative amount of alkaline earth metals. a′ + a′′ = a ,and a′ and a′′ None of them are negative; a is 1~2, b is 1~3, c is 1~4, and d is 1~2.
2. The method according to claim 1, characterized in that, The operating voltage for the lattice desalination method is 10~25V. vs. RHE, and / or, the lattice desalination process takes 1 to 16 hours.
3. The method according to claim 1, characterized in that, The electrocatalytic bismuth-based substrate material M a Bi b O c X d Topological lattice desalination includes the following steps: The electrode slurry containing the bismuth-based substrate material is used to form the working electrode of the electrocatalytic system. After the electrocatalytic system is activated, a bismuth-based crystalline material M is formed on the working electrode. a Bi b O c X d Topological lattice desalination.
4. The method according to claim 1, characterized in that, The electrocatalytic system is a photovoltaic coupled electrocatalytic system.