Magnetoelectric voltage photoelectrocatalyst, preparation method and application thereof

Abstract

This application provides a magnetovoltage electro-photocatalyst, its preparation method, and its application. The magnetovoltage electro-photocatalyst comprises a core and a shell coating at least a portion of the surface of the core. The core material includes A-site doped bismuth ferrite, B-site doped bismuth ferrite, or AB-site co-doped bismuth ferrite. The shell material includes TiO2. The chemical formula of the A-site doped bismuth ferrite is (Bi... 1‑x Na x )FeO3, 0<x≤0.99; the chemical formula of the B-site doped bismuth ferrite material is Bi(Fe 1‑y Mn y O3, 0 < y ≤ 0.99, M element includes one or more of Mn and Co; the chemical formula of the AB site co-doped bismuth ferrite material is (Bi 1‑a Na a (Fe) 1‑b M b O3, 0 < a ≤ 0.99, 0 < b ≤ 0.99. This magnetovoltage electro-photocatalyst exhibits high magnetovoltage electro-photocatalytic efficiency.

Description

Technical Field

[0001] This application relates to the field of magnetovoltage electro-photocatalysis technology, and in particular to magnetovoltage electro-photocatalysts, their preparation methods, and applications. Background Technology

[0002] Titanium dioxide (TiO2) photocatalysts have a wide band gap (approximately 3.2 eV for anatase phase), limiting their response to the ultraviolet region (λ < 387 nm). However, ultraviolet light accounts for less than 5% of the solar spectrum, resulting in low light energy utilization. Furthermore, photogenerated electron-hole pairs readily recombine in both the bulk and surface phases, further restricting quantum efficiency. Introducing a physical electric field within the TiO2 photoelectric semiconductor is an effective method to prevent the recombination of photogenerated electron-hole pairs.

[0003] However, in related technologies, TiO2 is still limited by its intrinsic band gap. Even when a physical electric field is applied, the light absorption range is still limited to the ultraviolet region, making it difficult to fully utilize visible light. Furthermore, the gain of the electric field on carrier separation is insufficient to compensate for the lack of light response, resulting in a low magneto-voltage electro-photocatalytic efficiency. Summary of the Invention

[0004] Based on this, this application provides a magneto-voltage electro-photocatalyst with high magneto-voltage electro-photocatalytic efficiency, its preparation method, and its application.

[0005] The first aspect of this application provides a magneto-voltage electro-optic catalyst, comprising:

[0006] The core material includes A-site doped bismuth ferrite material, B-site doped bismuth ferrite material, or AB-site co-doped bismuth ferrite material;

[0007] A shell layer covers at least a portion of the surface of the core; the material of the shell layer includes TiO2.

[0008] The chemical formula of the A-site doped bismuth ferrite material is (Bi 1-x Na x )FeO3, 0<x≤0.99; the chemical formula of the B-site doped bismuth ferrite material is Bi(FeO3, 0<x≤0.99). 1-y M y O3, 0 < y ≤ 0.99, M element includes one or more of Mn and Co; the chemical formula of the AB-site co-doped bismuth ferrite material is (Bi 1-a Na a (Fe) 1-b M b )O3, 0<x≤0.99, 0<a≤0.99, 0<b≤0.99.

[0009] In some embodiments, 0 < x ≤ 0.2.

[0010] In some embodiments, 0 < y ≤ 0.1.

[0011] In some embodiments, 0 < a ≤ 0.2, 0 < b ≤ 0.1.

[0012] In some embodiments, the mass ratio of the core to the shell is 1:(1-3).

[0013] In some embodiments, the magneto-voltage electro-photocatalyst is in the form of nanofibers.

[0014] In some embodiments, the diameter of the magneto-voltage electro-optic catalyst is 50 nm-200 nm.

[0015] In some embodiments, the A-site doped bismuth ferrite material, the B-site doped bismuth ferrite material, or the AB-site co-doped bismuth ferrite material are all single-phase rhombohedral perovskite structures.

[0016] The second aspect of this application provides a method for preparing a magneto-voltage electro-optic catalyst, comprising the following steps:

[0017] Prepare a core spinning precursor solution containing a first thickener and A-site doped bismuth ferrite material, B-site doped bismuth ferrite material, or AB-site co-doped bismuth ferrite material;

[0018] Preparation of shell spinning precursor solution containing titanium source and second thickener;

[0019] The core material spinning precursor solution and the shell material spinning precursor solution are simultaneously subjected to coaxial electrospinning to prepare spinning precursor nanofibers.

[0020] The spinning precursor nanofibers are subjected to a first drying treatment and a first sintering treatment to prepare the magneto-voltage electro-optic catalyst;

[0021] The chemical formula of the A-site doped bismuth ferrite material is (Bi 1-x Na x )FeO3, 0<x≤0.99; the chemical formula of the B-site doped bismuth ferrite material is Bi(FeO3, 0<x≤0.99). 1-y M y O3, 0 < y ≤ 0.99, M element includes one or more of Mn and Co; the chemical formula of the AB-site co-doped bismuth ferrite material is (Bi 1-a Na a (Fe) 1-b M b )O3, 0<a≤0.99, 0<b≤0.99;

[0022] The magneto-voltage electro-photocatalyst includes a core and a shell covering at least a portion of the surface of the core. The core is made of a material including the A-site doped bismuth ferrite material, the B-site doped bismuth ferrite material, or the AB-site co-doped bismuth ferrite material. The shell is made of TiO2.

[0023] In some embodiments, the titanium source includes one or more of tetrabutyl titanate and isopropyl titanate.

[0024] In some embodiments, the process parameters for coaxial electrospinning include: the inlet flow rate of the core material spinning precursor solution is 0.1 mL / h-0.5 mL / h, the inlet flow rate of the shell material spinning precursor solution is 0.1 mL / h-0.5 mL / h, the distance from the nozzle to the receiving plate is 10 cm-20 cm, and the spinning voltage is 15 kV-30 kV.

[0025] In some embodiments, the temperature of the first drying process is 100℃-300℃, and the time is 4h-24h.

[0026] In some embodiments, the temperature of the first sintering treatment is 500℃-700℃, and the time is 2h-5h.

[0027] In some embodiments, the step of preparing a core spinning precursor solution comprising a first thickener and A-site-doped bismuth ferrite material, B-site-doped bismuth ferrite material, or AB-site co-doped bismuth ferrite material includes:

[0028] Prepare a sol containing the A-site doped bismuth ferrite material, the B-site doped bismuth ferrite material, or the AB-site co-doped bismuth ferrite material;

[0029] The sol is mixed with the first thickener to prepare the core material spinning precursor solution.

[0030] In some embodiments, the molar concentration of the sol is 0.2 mol / L, and the volume-to-mass ratio of the sol to the first thickener is 10 mL:(2-5) g.

[0031] In some embodiments, the first thickener includes one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyvinyl alcohol.

[0032] In some embodiments, the step of preparing a shell spinning precursor solution comprising a titanium source and a second thickener includes:

[0033] Prepare a titanium source solution containing the titanium source;

[0034] The titanium source solution is mixed with the second thickener to prepare the shell spinning precursor solution.

[0035] In some embodiments, the molar concentration of the titanium source solution is 0.2 mol / L, and the volume-to-mass ratio of the titanium source solution to the second thickener is 10 mL:(2-5) g.

[0036] In some embodiments, the second thickener includes one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyvinyl alcohol.

[0037] In some embodiments, the method for preparing the A-site doped bismuth ferrite material includes:

[0038] A first solution comprising a sodium source, a first iron source, and a first bismuth source is prepared;

[0039] The first solution is subjected to a second drying process;

[0040] The product obtained from the second drying treatment is subjected to a second sintering treatment to prepare the A-site doped bismuth ferrite material.

[0041] In some embodiments, the sodium source includes at least one of sodium nitrate and sodium acetate.

[0042] In some embodiments, the first iron source includes at least one of ferric nitrate and ferric chloride.

[0043] In some embodiments, the first bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate.

[0044] In some embodiments, the temperature of the second drying process is 100℃-300℃, and the time is 4h-24h.

[0045] In some embodiments, the temperature of the second sintering treatment is 500℃-700℃, and the time is 2h-5h.

[0046] In some embodiments, the solvent of the first solution is dimethylformamide.

[0047] In some embodiments, the method for preparing the B-site doped bismuth ferrite material includes:

[0048] A second solution comprising a manganese source, a second iron source, and a second bismuth source is prepared.

[0049] The second solution is subjected to a third drying process;

[0050] The product obtained from the third drying process is subjected to a third sintering process to prepare the B-site doped bismuth ferrite material.

[0051] In some embodiments, the manganese source includes at least one of manganese nitrate and manganese acetate.

[0052] In some embodiments, the second iron source includes at least one of ferric nitrate and ferric chloride.

[0053] In some embodiments, the second bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate.

[0054] In some embodiments, the temperature of the third drying process is 100℃-300℃, and the time is 4h-24h.

[0055] In some embodiments, the temperature of the third sintering treatment is 500℃-700℃, and the time is 2h-5h.

[0056] In some embodiments, the solvent of the second solution is dimethylformamide.

[0057] In some embodiments, the method for preparing the AB-site co-doped bismuth ferrite material includes:

[0058] A third solution containing a sodium source, a manganese source, a third iron source, and a third bismuth source is prepared;

[0059] The third solution is subjected to a fourth drying process;

[0060] The product obtained from the fourth drying treatment is subjected to a fourth sintering treatment to prepare the AB-site co-doped bismuth ferrite material.

[0061] In some embodiments, the manganese source includes at least one of manganese nitrate and manganese acetate.

[0062] In some embodiments, the sodium source includes at least one of sodium nitrate and sodium acetate.

[0063] In some embodiments, the third iron source includes at least one of ferric nitrate and ferric chloride.

[0064] In some embodiments, the third bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate.

[0065] In some embodiments, the temperature of the fourth drying process is 100℃-300℃, and the time is 4h-24h.

[0066] In some embodiments, the temperature of the fourth sintering treatment is 500℃-700℃, and the time is 2h-5h.

[0067] In some embodiments, the solvent of the third solution is dimethylformamide.

[0068] The third aspect of this application provides the application of the magnetic voltage electro-photocatalyst prepared by the preparation methods of the magnetic voltage electro-photocatalyst of the first aspect of this application and the magnetic voltage electro-photocatalyst of the second aspect of this application in magnetic voltage electro-photocatalysis.

[0069] The aforementioned magneto-voltage electro-photocatalyst, firstly, leverages strain-lattice distortion to significantly enhance the magnetoelectric coupling, multiferroic properties, and optical performance of the A-site-doped or B-site-doped bismuth ferrite material in the core, achieving highly efficient magneto-voltage electro-photocatalysis. Secondly, under the influence of external ultrasound and alternating magnetic fields, this magneto-voltage electro-photocatalyst can construct a built-in electric field through the A-site-doped or B-site-doped bismuth ferrite material in the core, suppressing carrier recombination and improving magneto-voltage electro-photocatalytic efficiency. Thirdly, the intrinsic electric field at the interface of the multiferroic / photoelectric semiconductor pn junction between the core and shell can further suppress photogenerated electron-hole pair recombination, enhancing magneto-voltage electro-photocatalytic performance. Attached Figure Description

[0070] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0071] Figure 1 The results show the effects of Na doping at the A site on lattice distortion, multiferroic properties, and optical properties of bismuth ferrite materials in Examples 1-1 to 1-4 and Comparative Example 1.

[0072] Figure 2 The results show the effects of Na doping at the A site on the catalytic performance of bismuth ferrite materials in Examples 1-1 to 1-4 and Comparative Example 1.

[0073] Figure 3 The results show the effects of Mn doping on bismuth ferrite materials in Examples 2-1 to 2-4 and Comparative Example 1 on lattice distortion, multiferroic properties and optical properties.

[0074] Figure 4 The results show the morphology and structure characterization of the magneto-voltage electro-photocatalysts prepared in Examples 3-4 and Comparative Example 2.

[0075] Figure 5 The results show the physical property characterization and catalytic performance test results of the magnetovoltage electro-optic catalysts in Examples 3-4 and Comparative Example 2.

[0076] in, Figure 1In this context, "2 Theta (degree)" refers to 2θ (degrees); "Intensity (au)" refers to intensity (any unit); "Na doping ratio (x)" refers to the sodium doping ratio; "Raman shift" refers to the Raman shift; "Magnetic field" refers to the magnetic field; "Na-doped BiFeO3" refers to sodium-doped bismuth ferrite; "Wavelength" refers to the wavelength; and "Nadoping content" refers to the sodium doping content.

[0077] Figure 2 In this context, "Time" refers to time; "Piezo" refers to piezoelectricity; "piezo-photo" refers to piezo-photoelectric effect; "ME-catalysis" refers to magneto-electrocatalysis; "ME-piezo-photo" refers to magneto-piezo-photocatalysis; "k value" refers to the k-value; and "Synergistic factor" refers to the synergistic factor.

[0078] Figure 4 In this context, "co-axial electrospinning" refers to coaxial electrospinning; "Precursor NFs" refers to precursor nanofibers; "Dried NFs" refers to dried fibers; "fibrous pn heterojunction" refers to fibrous pn heterojunction structures; and "catalyst mat" refers to catalytic fiber mat.

[0079] Figure 5 In this context, "Temperature" refers to temperature; "Relativistic pressure" refers to relative pressure; "Quantity Adsorbed" refers to the amount of adsorption; "Desorption" refers to desorption; "Absorption" refers to absorption; and "Pore diameter" refers to pore size. Detailed Implementation

[0080] To facilitate understanding of this application, a more complete description of the application will be provided below with reference to relevant embodiments. Preferred embodiments of the application are given below. However, the application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0081] Unless otherwise defined, all technical and scientific terms used herein 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 particular embodiments only and is not intended to be limiting of the application.

[0082] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0083] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0084] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0085] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0086] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0087] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0088] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0089] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0090] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0091] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0092] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, but sequentially is preferred.

[0093] Titanium dioxide (TiO2) photocatalysts have a wide band gap (approximately 3.2 eV for anatase phase), limiting their response to the ultraviolet region (λ < 387 nm). However, ultraviolet light accounts for less than 5% of the solar spectrum, resulting in low light energy utilization. Furthermore, photogenerated electron-hole pairs readily recombine in both the bulk and surface phases, further restricting quantum efficiency. Introducing a physical electric field within the TiO2 photoelectric semiconductor is an effective method for separating the recombination of photogenerated electron-hole pairs. However, in related technologies, TiO2 remains limited by its intrinsic band gap; even with an applied physical electric field, the light absorption range remains confined to the ultraviolet region, making it difficult to fully utilize visible light. Moreover, the gain from the electric field in carrier separation is insufficient to compensate for the inadequate photoresponse, resulting in a still relatively low magneto-voltage electro-photocatalytic efficiency.

[0094] The study found that bismuth ferrite possesses multiferroic properties and is also a semiconductor, enabling it to achieve magneto-poleo-electro-photocatalytic performance. However, the spin-cycloid structure of bismuth ferrite results in a weak magnetoelectric coupling effect. Therefore, it is necessary to break its 62-nanometer-period spin-cycloid structure to improve its ferroelectricity, piezoelectricity, magnetoelectric coupling, and optical properties.

[0095] To address the aforementioned issues, this application employs strain engineering to dope bismuth ferrite at either the A-site or B-site, thereby controlling the multiferroic properties, magnetoelectric coupling, and optical properties of bismuth ferrite based on strain-lattice distortion coupling. Furthermore, it utilizes coaxial electrospinning technology to prepare nanofibers with a core-shell structure, constructing a multiferroic / optoelectronic semiconductor fiber heterojunction. This allows for magneto-voltage electro-photocatalytic applications through ultrasonic, optical radiation, and alternating magnetic field excitation.

[0096] The first aspect of this application provides a magneto-voltage electro-optic catalyst, comprising a core and a shell coating at least a portion of the surface of the core. The core material comprises A-site doped bismuth ferrite, B-site doped bismuth ferrite, or AB-site co-doped bismuth ferrite, and the shell material comprises TiO2. The chemical formula of the A-site doped bismuth ferrite is (Bi... 1-x Na x )FeO3, 0<x≤0.99; the chemical formula of the B-site doped bismuth ferrite material is Bi(Fe 1-y Mn y O3, 0 < y ≤ 0.99, M element includes one or more of Mn and Co; the chemical formula of the AB site co-doped bismuth ferrite material is (Bi 1-a Na a (Fe) 1-b M b )O3, 0<a≤0.99, 0<b≤0.99.

[0097] As an example, x can be, but is not limited to, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.99, or any range between any two of the above values.

[0098] y can be, but is not limited to, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.99, or any range between any two of the above values.

[0099] a can be, but is not limited to, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.99, or a range between any two of the above values. b can be, but is not limited to, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.99, or a range between any two of the above values.

[0100] Understandably, the magneto-voltage electro-photocatalyst of this application, firstly, leverages strain-lattice distortion to significantly enhance the magnetoelectric coupling, multiferroic properties, and optical performance of the A-site-doped or B-site-doped bismuth ferrite material in the core, achieving highly efficient magneto-voltage electro-photocatalysis. Secondly, under the influence of external ultrasound and alternating magnetic fields, this magneto-voltage electro-photocatalyst can construct a built-in electric field through the A-site-doped or B-site-doped bismuth ferrite material in the core, suppressing carrier recombination and improving the magneto-voltage electro-photocatalytic efficiency. Thirdly, the intrinsic electric field at the interface of the multiferroic / photoelectric semiconductor pn junction between the core and shell can further suppress photogenerated electron-hole pair recombination, enhancing the magneto-voltage electro-photocatalytic performance.

[0101] It should be noted that A-site doped bismuth ferrite materials, B-site doped bismuth ferrite materials, or AB-site co-doped bismuth ferrite materials belong to single-phase multiferroic optoelectronic semiconductor materials.

[0102] The magneto-voltage electro-photocatalyst is a single-phase multiferroic optoelectronic semiconductor composite material. A single-phase multiferroic optoelectronic semiconductor composite material refers to a core-shell structure fiber pn junction constructed from BiFeO3 multiferroic material co-doped at A-site, B-site, or AB-site and optoelectronic semiconductor TiO2.

[0103] In some alternative implementations, 0 < x ≤ 0.2.

[0104] As one possible implementation, 0 < y ≤ 0.1.

[0105] In some exemplary implementations, 0 < a ≤ 0.2, 0 < b ≤ 0.1.

[0106] In some embodiments, the mass ratio of the core to the shell is 1:(1-3); for example, it can be, but is not limited to, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, or any range between two of the above ratios. This significantly improves the catalytic rate constant.

[0107] As one possible implementation method, the magneto-voltage electro-photocatalyst is in the form of nanofibers.

[0108] In some optional embodiments, the magnetovoltage electro-photocatalyst is in the form of nanofibers, with a diameter of 50 nm to 200 nm; for example, it can be, but is not limited to, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, or any range between two of the above diameters. Therefore, the magnetovoltage electro-photocatalyst has a small diameter and a large specific surface area, which can increase the number of catalytic active sites and significantly improve the catalytic effect.

[0109] In some embodiments, the A-site-doped bismuth ferrite material, the B-site-doped bismuth ferrite material, or the AB-site co-doped bismuth ferrite material are all single-phase rhombohedral perovskite structures. Therefore, the bismuth ferrite material has a stable chemical structure, which is beneficial for catalysis.

[0110] The "single-phase rhombohedral perovskite structure" mentioned in the context refers to a structure that can deform under stress / strain to form a rhombohedral perovskite structure.

[0111] As one possible implementation, bismuth ferrite materials doped at the A-site, bismuth ferrite materials doped at the B-site, or bismuth ferrite materials co-doped at the AB-site are all solid solutions. This helps to reduce or even avoid element precipitation and improve the stability of the chemical structure.

[0112] A second aspect of this application provides a method for preparing a magneto-voltage electro-photocatalyst, which can be used to prepare the aforementioned magneto-voltage electro-photocatalyst. The preparation method includes the following steps:

[0113] A core material spinning precursor solution containing a first thickener and A-site doped bismuth ferrite, B-site doped bismuth ferrite, or AB-site co-doped bismuth ferrite is prepared; a shell material spinning precursor solution containing a titanium source and a second thickener is prepared; the core material spinning precursor solution and the shell material spinning precursor solution are simultaneously subjected to coaxial electrospinning to prepare spinning precursor nanofibers; the spinning precursor nanofibers are subjected to a first drying treatment and a first sintering treatment to prepare a magneto-voltage electro-photocatalyst; wherein, the chemical formula of the A-site doped bismuth ferrite is (Bi 1-x Na x )FeO3, 0<x≤0.99; the chemical formula of the B-site doped bismuth ferrite material is Bi(Fe 1-y Mn y O3, 0 < y ≤ 0.99, M element includes one or more of Mn and Co; the chemical formula of the AB site co-doped bismuth ferrite material is (Bi 1-a Na a (Fe) 1-b M bO3, 0<a≤0.99, 0<b≤0.99; the magneto-voltage electro-photocatalyst includes a core and a shell covering at least part of the surface of the core. The core material includes A-site doped bismuth ferrite material, B-site doped bismuth ferrite material or AB-site co-doped bismuth ferrite material, and the shell material includes TiO2.

[0114] Understandably, the magnetic voltage electro-photocatalyst prepared by this method has similar technical solutions and advantages to the magnetic voltage electro-photocatalyst described above, and will not be repeated here.

[0115] In some embodiments, the titanium source includes one or more of tetrabutyl titanate and isopropyl titanate.

[0116] As one possible implementation, during coaxial electrospinning, the infeed flow rate of the core material spinning precursor solution is 0.1 mL / h to 0.5 mL / h; for example, it can be, but is not limited to, 0.1 mL / h, 0.2 mL / h, 0.3 mL / h, 0.4 mL / h, 0.5 mL / h, or any range between two of the above flow rates. This is beneficial for controlling the two-phase ratio of the core and shell in the magneto-electric photocatalyst, optimizing the magneto-electric coupling and photoelectric conversion efficiency.

[0117] As one possible implementation, during coaxial electrospinning, the infeed flow rate of the shell spinning precursor solution is 0.1 mL / h to 0.5 mL / h; for example, it can be, but is not limited to, 0.1 mL / h, 0.2 mL / h, 0.3 mL / h, 0.4 mL / h, 0.5 mL / h, or any range between two of the above flow rates. This is beneficial for controlling the core-shell two-phase ratio in the magneto-electric photocatalyst, optimizing magneto-electric coupling and photoelectric conversion efficiency.

[0118] In some alternative implementations, during coaxial electrospinning, the distance from the nozzle to the receiving plate is 10cm-20cm; for example, it can be, but is not limited to, 10cm, 12cm, 14cm, 16cm, 18cm, 20cm or any range between two of the above distances.

[0119] As one possible implementation, the spinning voltage during coaxial electrospinning is 15kV-30kV; for example, it can be, but is not limited to, 15kV, 16kV, 18kV, 20kV, 22kV, 24kV, 26kV, 28kV, 30kV, or any range between two of the above voltages.

[0120] In some alternative embodiments, the temperature of the first drying treatment is 100°C-300°C; for example, it can be, but is not limited to, 100°C, 150°C, 200°C, 250°C, 300°C, or any range between two of the above temperatures. Thus, by controlling the evaporation rate through temperature regulation, it is beneficial to maintain the nanofiber structure of the spinning precursor.

[0121] In some embodiments, the first drying treatment time is 4-24 hours; for example, it can be, but is not limited to, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, or any range between two of the above times. This is beneficial for the formation of a dry gel from the spinning precursor nanofibers, avoiding fiber morphology collapse during the sintering process.

[0122] In some embodiments, the temperature of the first sintering treatment is 500°C-700°C; for example, it can be, but is not limited to, 500°C, 550°C, 600°C, 650°C, 700°C, or any range between two of the above temperatures. Thus, a stable perovskite structure is formed through crystallization.

[0123] As one possible implementation, the first sintering treatment time is 2-5 hours; for example, it can be, but is not limited to, 2 hours, 3 hours, 4 hours, 5 hours, or any range between two of the above times. This facilitates control of the grain size, thereby controlling the fiber morphology of the magneto-voltage electro-optic catalyst.

[0124] In some embodiments, the step of preparing a core spinning precursor solution comprising a first thickener and A-site doped bismuth ferrite material, B-site doped bismuth ferrite material, or AB-site co-doped bismuth ferrite material includes: preparing a sol comprising A-site doped bismuth ferrite material, B-site doped bismuth ferrite material, or AB-site co-doped bismuth ferrite material; and mixing the sol with the first thickener to prepare the core spinning precursor solution.

[0125] As one possible implementation, the molar concentration of the sol is 0.2 mol / L, and the volume-to-mass ratio of the sol to the first thickener is 10 mL:(2-5) g; for example, it can be, but is not limited to, 10 mL:2 g, 10 mL:3 g, 10 mL:4 g, 10 mL:5 g, or any range between the two aforementioned volume-to-mass ratios. This allows for the control of the obtained magneto-voltage electro-photocatalyst to have a suitable diameter.

[0126] In some embodiments, the first thickener includes one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyvinyl alcohol.

[0127] In some embodiments, the step of preparing a shell spinning precursor solution comprising a titanium source and a second thickener includes: preparing a titanium source solution comprising a titanium source; and mixing the titanium source solution with the second thickener to prepare the shell spinning precursor solution.

[0128] In some optional embodiments, the molar concentration of the titanium source solution is 0.2 mol / L, and the volume-to-mass ratio of the titanium source solution to the second thickener is 10 mL:(2-5) g; for example, it can be, but is not limited to, 10 mL:2 g, 10 mL:3 g, 10 mL:4 g, 10 mL:5 g, or any range between the above two volume-to-mass ratios. Thus, by controlling the concentration of the shell spinning precursor solution, a magneto-voltage electro-photocatalyst with suitable shell thickness and shell particle size is obtained.

[0129] In some alternative embodiments, the second thickener includes one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyvinyl alcohol.

[0130] In some embodiments, the preparation method of A-site doped bismuth ferrite material includes: preparing a first solution containing a sodium source, a first iron source, and a first bismuth source; subjecting the first solution to a second drying treatment; and subjecting the product obtained from the second drying treatment to a second sintering treatment to prepare the A-site doped bismuth ferrite material. The ferroelectricity and band gap structure of bismuth ferrite can be controlled by A-site Na doping.

[0131] As one possible implementation, the sodium source includes at least one of sodium nitrate and sodium acetate.

[0132] In some alternative embodiments, the first iron source includes at least one of ferric nitrate and ferric chloride.

[0133] In some of these embodiments, the first bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate.

[0134] In some embodiments, the temperature of the second drying process is 100°C-300°C; for example, it can be, but is not limited to, 100°C, 150°C, 200°C, 250°C, 300°C, or any range between two of the above temperatures. Thus, by controlling the drying temperature, a bismuth ferrite material powder sample with uniform morphology is obtained.

[0135] As one possible implementation, the second drying process takes 4-24 hours; for example, it can be, but is not limited to, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, or any range between two of the above times. This controls the amount of solvent evaporation, resulting in a stable bismuth ferrite powder sample.

[0136] In some embodiments, the temperature of the second sintering treatment is 500°C-700°C; for example, it can be, but is not limited to, 500°C, 550°C, 600°C, 650°C, 700°C, or any range between two of the above temperatures. Thus, the crystallinity of the particles constituting the bismuth ferrite material powder sample is controlled by sintering.

[0137] As one possible implementation, the second sintering treatment time is 2-5 hours; for example, it can be, but is not limited to, 2 hours, 3 hours, 4 hours, 5 hours, or any range between two of the above times. This controls the crystallinity and grain size of the bismuth ferrite material.

[0138] In some alternative embodiments, the solvent of the first solution is dimethylformamide.

[0139] In some embodiments, the preparation method of B-site doped bismuth ferrite material includes: preparing a second solution containing a manganese source, a second iron source, and a second bismuth source; subjecting the second solution to a third drying treatment; and subjecting the product obtained from the third drying treatment to a third sintering treatment to prepare the B-site doped bismuth ferrite material. The magnetic and magnetoelectric coupling properties of bismuth ferrite can be tuned by B-site Mn doping.

[0140] In some embodiments, the manganese source includes at least one of manganese nitrate and manganese acetate.

[0141] As one possible implementation, the second iron source includes at least one of ferric nitrate and ferric chloride.

[0142] In some alternative embodiments, the second bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate.

[0143] In some embodiments, the temperature of the third drying process is 100°C-300°C; for example, it can be, but is not limited to, 100°C, 150°C, 200°C, 250°C, 300°C, or any range between two of the above temperatures. Thus, by controlling the drying temperature, a bismuth ferrite material powder sample with uniform morphology is obtained.

[0144] As one possible implementation, the third drying process takes 4-24 hours; for example, it can be, but is not limited to, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, or any range between two of the above times. This controls the amount of solvent evaporation, resulting in a stable bismuth ferrite powder sample.

[0145] In some embodiments, the temperature of the third sintering treatment is 500°C-700°C; for example, it can be, but is not limited to, 500°C, 550°C, 600°C, 650°C, 700°C, or any range between two of the above temperatures. Thus, the crystallinity of the particles constituting the bismuth ferrite material powder sample is controlled by sintering.

[0146] As one possible implementation, the third sintering treatment time is 2-5 hours; for example, it can be, but is not limited to, 2 hours, 3 hours, 4 hours, 5 hours, or any range between two of the above times. This controls the crystallinity and grain size of the bismuth ferrite material.

[0147] In some alternative embodiments, the solvent for the second solution is dimethylformamide.

[0148] In some embodiments, the preparation method of AB-site co-doped bismuth ferrite material includes: preparing a third solution containing a sodium source, a manganese source, a third iron source and a third bismuth source; performing a fourth drying treatment on the third solution; and performing a fourth sintering treatment on the product obtained from the fourth drying treatment to prepare AB-site co-doped bismuth ferrite material.

[0149] In some alternative embodiments, the manganese source includes at least one of manganese nitrate and manganese acetate.

[0150] In some embodiments, the sodium source includes at least one of sodium nitrate and sodium acetate.

[0151] As one possible implementation, the third iron source includes at least one of ferric nitrate and ferric chloride.

[0152] In some of these embodiments, the third bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate.

[0153] In some embodiments, the temperature of the fourth drying process is 100°C-300°C; for example, it can be, but is not limited to, 100°C, 150°C, 200°C, 250°C, 300°C, or any range between two of the above temperatures. Thus, by controlling the drying temperature, a bismuth ferrite material powder sample with uniform morphology is obtained.

[0154] As one possible implementation, the fourth drying process takes 4-24 hours; for example, it can be, but is not limited to, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, or any range between two of the above times. This controls the amount of solvent evaporation, resulting in a stable bismuth ferrite powder sample.

[0155] In some embodiments, the temperature of the fourth sintering process is 500°C-700°C; for example, it can be, but is not limited to, 500°C, 550°C, 600°C, 650°C, 700°C, or any range between two of the above temperatures. Thus, the crystallinity of the particles constituting the bismuth ferrite material powder sample is controlled by sintering.

[0156] As one possible implementation, the fourth sintering treatment time is 2-5 hours; for example, it can be, but is not limited to, 2 hours, 3 hours, 4 hours, 5 hours, or any range between two of the above times. This controls the crystallinity and grain size of the bismuth ferrite material.

[0157] In some alternative embodiments, the solvent for the third solution is dimethylformamide.

[0158] The third aspect of this application provides the application of the magnetic voltage electro-photocatalyst prepared by the preparation methods of the magnetic voltage electro-photocatalyst of the first aspect of this application and the magnetic voltage electro-photocatalyst of the second aspect of this application in magnetic voltage electro-photocatalysis.

[0159] The technical solutions of this application will be described in detail below with reference to specific embodiments. It should be understood that these embodiments are only for illustrating this application and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application first, or follow experimental manuals or conventional conditions in the field, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the field.

[0160] In the specific embodiments described below, the measurement parameters involving raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. Temperature and time parameters are subject to acceptable deviations due to instrument testing accuracy or operational precision.

[0161] I. Preparation of A-site doped bismuth ferrite materials

[0162] Example 1-1

[0163] Sodium nitrate, bismuth nitrate pentahydrate, and ferric nitrate nonahydrate were added to N,N-dimethylformamide in a molar ratio of 0.05:0.97:1 and completely dissolved to prepare a first solution with a molar concentration of 0.2 M. The solution was then brought to a final volume of 10 mL. After thorough stirring, the solution was dried at 200 °C for 4 hours to form a gel. This gel was then ground and sintered in a muffle furnace at 550 °C for 2 hours to obtain the A-site doped bismuth ferrite material (Bi). 0.95 Na 0.05 FeO3 nanopowder sample.

[0164] Examples 1-2

[0165] The preparation methods of Examples 1-2 are similar to those of Example 1-1, except that the molar ratio of sodium nitrate, bismuth nitrate pentahydrate, and ferric nitrate nonahydrate in Examples 1-2 is 0.1:0.92:1; A-site doped bismuth ferrite material (Bi) is obtained. 0.9 Na 0.1 FeO3 nanopowder sample.

[0166] Examples 1-3

[0167] The preparation methods of Examples 1-3 are similar to those of Example 1-1, except that the molar ratio of sodium nitrate, bismuth nitrate pentahydrate, and ferric nitrate nonahydrate in Examples 1-3 is 0.15:0.87:1; A-site doped bismuth ferrite material (Bi) is obtained. 0.85 Na 0.15 FeO3 nanopowder sample.

[0168] Examples 1-4

[0169] The preparation methods of Examples 1-4 are similar to those of Example 1-1, except that the molar ratio of sodium nitrate, bismuth nitrate pentahydrate, and ferric nitrate nonahydrate in Examples 1-4 is 0.2:0.82:1; A-site doped bismuth ferrite material (Bi) is obtained. 0.8 Na 0.2 FeO3 nanopowder sample.

[0170] Comparative Example 1

[0171] Bismuth nitrate pentahydrate and ferric nitrate nonahydrate were added to N,N-dimethylformamide at a molar ratio of 1.02:1, and the mixture was stirred continuously until the solution became transparent, brown, and clear. The solution was then heated in a drying oven at 200 °C for 4 hours until the clear sol completely transformed into a yellow-brown gel. After that, it was annealed at 550 °C for 2 hours, and finally ground into a nanoparticle sample to obtain bismuth ferrite BiFeO3.

[0172] The effects of Na doping at the A site on the lattice distortion, multiferroic properties, and optical properties of bismuth ferrite materials in Examples 1-1 to 1-4 and Comparative Example 1 were tested using X-ray diffraction (XRD).

[0173] Test results are as follows Figure 1 As shown. Figure 1 The XRD patterns of bismuth ferrite samples in Comparative Example 1, Example 1-1, Example 1-2, Example 1-3, and Example 1-4 are respectively. Figure 1 In the figure, f represents the effect of the c-axis length and cell volume on the Na ion doping concentration. Figure 1 In the figure, g represents the Raman spectra of Examples 1-1 to 1-4 and Comparative Example 1. Figure 1 In the middle, h represents the hysteresis loop of Examples 1-1 to 1-4. Figure 1 In this equation, i represents the effect of Na ion doping concentration on the saturation magnetization, remanent magnetization, and coercivity of the bismuth ferrite material. Figure 1 In the middle, j represents the ultraviolet-visible reflectance spectra of Examples 1-1 to 1-4. Figure 1 In this context, k represents the band gap (E) of Examples 1-1 to 1-4. g )structure. Figure 1 In the middle, l represents the optical band gap E of bismuth ferrite material. g Graph showing the variation of Na ion doping concentration.

[0174] Depend on Figure 1 As can be seen, all XRD patterns exhibit the typical broad peak characteristics of nanomaterials and can be indexed as a single-phase rhombohedral perovskite structure, confirming the formation of a solid solution throughout the doping range. In pure BiFeO3 (Comparative Example 1) and (Bi...0.9 Na 0.1) In FeO3 (x=0.1, Examples 1-2), trace amounts of Bi2Fe4O9 impurity phase appeared due to localized Bi excess. Due to Na-induced distortion, the lattice parameters of pure BiFeO3 are slightly larger than previously reported values ​​(a = b = 5.777 Å, c = 13.867 Å, ​​V = 373.57 ų). Figure 1 As shown in f, both the c-axis length and the cell volume decrease monotonically with increasing Na content, and tend to stabilize after x > 0.05. This is consistent with the fact that the Na content is relatively small. + (95 pm) Replaces Bi 3+ The result is consistent with (108 pm), indicating that the solid solution limit is approximately x=0.05.

[0175] The stability of perovskites is determined by the Goldschmidt tolerance factor (t):

[0176]

[0177] Where, r A r B and r O These represent the ionic radii of the A-site ion, B-site ion, and oxygen ion, respectively. For Na-doped bismuth ferrite, t≈0.81, which is within the stable range of 0.77-0.99, meaning that Na substitution modulates the tilt of the FeO6 octahedron (e.g., Figure 1 As shown in a), this affects multiferroic properties and magnetoelectric coupling.

[0178] Raman spectroscopy (e.g.) Figure 1 (As shown in g) Utilizing its high sensitivity to atomic vibrations, the local distortion of Na-doped bismuth ferrite at the A site was detected. Undoped bismuth ferrite at 73 cm⁻¹... -1 128cm -1 and 156cm -1 Characteristic peaks are observed at x=0.2. When x=0.2, these peaks shift to 73cm. -1 135cm -1 and 163cm -1 Furthermore, the intensity increases. The blue shift of the high-frequency peak confirms lattice contraction, while the enhanced intensity reflects more significant distortion and asymmetric vibrations, indicating improved ferroelectric / piezoelectric properties, which is beneficial for piezoelectronic applications.

[0179] Unlike bulk bismuth ferrite, where magnetization is suppressed by G-type antiferromagnetism (G-type AFM) and cycloidal spin structure (period approximately 62 nm), narrow MH loops (such as...) Figure 1Figure h) reveals the presence of weak ferromagnetism (WFM) at room temperature. G-type antiferromagnetism has two antiferromagnetically coupled sublattices, each containing a ferromagnetically arranged structure. Grain boundaries disrupt long-range antiferromagnetic order. Furthermore, doping alters the Fe-O-Fe superexchange interaction. Surface strain and lattice distortion generate uncompensated spins through localized spin tilting, thus positively contributing to the net magnetization. Therefore, the generation of weak ferromagnetism stems from: (i) size effects suppressing cycloidal structures when grain size is below 62 nm; and (ii) a large surface area to volume ratio promoting uncompensated spins.

[0180] The effect of Na doping on ferromagnetism (e.g.) Figure 1 As shown in i): MS, Mr, and Hc generally decrease with increasing Na content because: (i) the Fe-O-Fe bond angle decreases, weakening the superexchange effect; (ii) nonmagnetic Na... + Ions disrupt the Fe-O-Fe superexchange network; (iii) shorter Na-O bonds disturb the superexchange pathway. Notably, the anomaly at x=0.1 (magnetization comparable to x=0.05) originates from a small amount of Bi₂Fe₄O₉ impurity (e.g., ... Figure 1 (as shown in c).

[0181] The effects of Na doping on the optical properties of bismuth ferrite were investigated using ultraviolet-visible diffuse reflectance spectroscopy (DRS) and Tauc plots. The results are as follows: Figure 1 j and Figure 1 As shown in Figure k, a strong absorption edge appears at approximately 550 nm, corresponding to an electronic transition from the O 2p valence band (VB) to the Fe 3d conduction band (CB). The absorbance in the 600–800 nm range decreases with increasing Na content, indicating the presence of a band tail state.

[0182] like Figure 1 As shown in Figure 1, the optical band gap E g The band gap decreases monotonically with increasing Na content: 1.87 (x=0.05), 1.77 (x=0.1), 1.68 (x=0.15), and 1.52 eV (x=0.2), all lower than that of pure bismuth ferrite (approximately 2.2 eV). Therefore, Na doping at the A site effectively reduces the band gap, enabling a tunable electronic structure. Combined with enhanced multiferroic properties, Na-doped bismuth ferrite becomes a promising platform for optimizing magnetoelectric-piezoelectric-optoelectronics.

[0183] In summary, by Figure 1 The results show that A-site doped bismuth ferrite materials have the effect of enhancing ferroelectricity and reducing band gap.

[0184] The effects of Na doping at the A site on the catalytic performance of bismuth ferrite materials were investigated in Examples 1-1 to 1-4 and Comparative Example 1. The testing method involved determining the degradation rate of MO aqueous solution by the catalyst using UV-Vis absorption spectroscopy, and comparing the degradation rates of different catalysts to evaluate their catalytic activity. The MO aqueous solution was prepared by dissolving 5g of solid MO powder in 1L of pure water and stirring for 2 hours. MO refers to methyl orange.

[0185] Test results are as follows Figure 2 As shown. Among them, Figure 2 In the figures, a and b represent the piezoelectric catalytic performance of bismuth ferrite samples from Comparative Example 1, Example 1-1, Example 1-2, Example 1-3, and Example 1-4. Figure 2 c and d represent the photocatalytic performance analysis results of bismuth ferrite samples from Comparative Example 1, Example 1-1, Example 1-2, Example 1-3, and Example 1-4. Figure 2 In the figures, e and f represent the piezoelectric photocatalytic performance analysis results of the bismuth ferrite samples from Comparative Example 1, Example 1-1, Example 1-2, Example 1-3, and Example 1-4. Figure 2 In the figure, g and h represent the magnetoelectrocatalytic performance analysis results of the bismuth ferrite samples of Comparative Example 1, Example 1-1, Example 1-2, Example 1-3, and Example 1-4. Figure 2 In the figure, i and j represent the magnetovoltage electrophotocatalytic performance analysis results of the bismuth ferrite samples of Comparative Example 1, Example 1-1, Example 1-2, Example 1-3, and Example 1-4. Figure 2 In the figure, k represents the comparison of the degradation rate constant k values ​​of bismuth ferrite samples in Comparative Example 1, Example 1-1, Example 1-2, Example 1-3, and Example 1-4 under different catalytic modes. Figure 2 In the figure, l represents the catalytic rate constant k and the corresponding synergistic factor of bismuth ferrite material as a function of Na ion doping concentration.

[0186] Depend on Figure 2 As can be seen from k, in Example 1-1, the A-site doped bismuth ferrite material (Bi) 0.9 Na 0.1 FeO3 exhibited the best performance in all modes: the photocatalytic degradation efficiency was 38% (rate constant k = 0.83 × 10⁻⁶). -2 min -1 The piezoelectric catalysis rate was 29% (0.55 × 10⁻⁶). -2 min -1 The piezoelectric-photocatalytic efficiency was 55% (1.46 × 10⁻⁶). -2 min -1 The magneto-electrocatalysis rate was 61% (1.57 × 10⁻⁶). -2 min -1The magnetoelectric-piezoelectric-photocatalysis efficiency was 78% (2.69 × 10⁻⁶). -2 min -1 The progressively improving performance from single-field excitation to multi-field excitation demonstrates the synergistic effect of coupled stimulation. The highest efficiency of magnetoelectric-piezoelectric-photocatalysis is attributed to the combined effect of the built-in electric fields induced by both mechanical and magnetoelectric processes. These fields synergistically enhance piezoelectric-photoelectronics and promote efficient carrier separation.

[0187] Depend on Figure 2 As can be seen from the data, the synergistic factor value of piezoelectric photocatalysis is 1.03, and the synergistic factor value of magnetoelectric photocatalysis is 1.25. Both are greater than 1, indicating that the catalytic degradation rate of piezoelectric photocatalysis and the catalytic degradation rate of magnetoelectric photocatalysis are positively correlated.

[0188] II. Preparation of B-site doped bismuth ferrite materials or AB-site co-doped bismuth ferrite materials

[0189] Example 2-1

[0190] Bismuth nitrate pentahydrate, ferric nitrate nonahydrate, and manganese nitrate hexahydrate were added to N,N-dimethylformamide in a molar ratio of 1.02:0.9:0.1 and completely dissolved to prepare a first solution with a molar concentration of 0.2 M. The solution was then brought to a final volume of 10 mL. After thorough stirring, the solution was dried at 200 °C for 4 hours to form a gel. This gel was then ground and sintered in a muffle furnace at 550 °C for 2 hours to obtain the B-site doped bismuth ferrite material Bi(Fe₂O₃)₂O₃. 0.9 Mn 0.1 O3 nanopowder sample.

[0191] Example 2-2

[0192] Bismuth nitrate pentahydrate, ferric nitrate nonahydrate, manganese nitrate hexahydrate, and cobalt nitrate were added to N,N-dimethylformamide in a molar ratio of 1.02:0.9:0.09:0.01 and completely dissolved to prepare a first solution with a molar concentration of 0.2 M. The solution was then brought to a final volume of 10 mL. After thorough stirring, the solution was dried at 200 °C for 4 hours to form a gel. This gel was then ground and sintered in a muffle furnace at 550 °C for 2 hours to obtain the B-site doped bismuth ferrite material Bi(Fe₂O₃)₂O₃. 0.9 Mn 0.09 Co 0.01 O3 nanopowder sample.

[0193] Example 2-3

[0194] Sodium nitrate, bismuth nitrate pentahydrate, ferric nitrate nonahydrate, and manganese nitrate hexahydrate were added to N,N-dimethylformamide in a molar ratio of 0.05:0.97:0.9:0.1 and completely dissolved to prepare a first solution with a molar concentration of 0.2 M. The solution was then brought to a final volume of 10 mL. After thorough stirring, the solution was dried at 200 °C for 4 hours to form a gel. This gel was then ground and sintered in a muffle furnace at 550 °C for 2 hours to obtain B-site doped bismuth ferrite material (Bi). 0.95 Na 0.05 (Fe) 0.9 Mn 0.1 O3 nanopowder sample.

[0195] Examples 2-4

[0196] Sodium nitrate, bismuth nitrate pentahydrate, ferric nitrate nonahydrate, manganese nitrate hexahydrate, and cobalt nitrate were added to N,N-dimethylformamide in a molar ratio of 0.05:0.97:0.9:0.09:0.01 and completely dissolved to prepare a first solution with a molar concentration of 0.2 M. The solution was then brought to a final volume of 10 mL. After thorough stirring, the solution was dried at 200 °C for 4 hours to form a gel. This gel was then ground and sintered in a muffle furnace at 550 °C for 2 hours to obtain B-site doped bismuth ferrite material (Bi). 0.95 Na 0.05 (Fe) 0.9 Mn 0.09 Co 0.01 O3 nanopowder sample.

[0197] The effects of Mn doping on bismuth ferrite materials in Examples 2-1 to 2-4 and Comparative Example 1 on lattice distortion, multiferroic properties, and optical properties were investigated. The testing methods included: XRD refinement to study lattice distortion, VSM and Raman spectroscopy analysis to study multiferroic properties, and UV-Vis reflectance spectroscopy analysis to analyze the band gap. The results of band gap variation with doping concentration were discussed.

[0198] Test results are as follows Figure 3 As shown. Figure 3 In the middle, a to d represent Bi(Fe) 0.9 Mn 0.1 XRD pattern, Raman spectrum, hysteresis loop and UV-Vis reflectance spectrum of O3. Figure 3 In the figures, e and f represent the photocatalytic performance analysis results of Examples 1-1, 2-1 to 2-4, and Comparative Example 1. Figure 3 In the figure, g and h represent the magneto-electrocatalytic performance analysis results of Examples 1-1, 2-1 to 2-4, and Comparative Example 1. Figure 3 In the figure, i and j represent the magnetovoltage electrophotocatalytic performance analysis results of Examples 1-1, 2-1 to 2-4, and Comparative Example 1. Figure 3In the figure, k represents a comparison of the degradation rate constant k values ​​of bismuth ferrite samples from Examples 1-1, 2-1 to 2-4, and Comparative Example 1 under different catalytic modes. Figure 3 The figure shows a comparison of the catalytic rate constants of bismuth ferrite materials and their corresponding magnetovoltage electro-photocatalytic synergistic factors.

[0199] Depend on Figure 3 As can be seen from a to d, in Example 2-1, the bismuth ferrite material (Bi(Fe) doped with Mn at the B site) 0.9 Mn 0.1 O3) retains the perovskite structure and can optimize ferroelectricity, enhance magnetism, and reduce the band gap. Figure 3 From e to k, it can be seen that magnetovoltage electrophotocatalysis can significantly improve catalytic performance. Figure 3 As can be seen from the figure, B-site Mn doping has the best synergistic effect.

[0200] III. Preparation of Magnetovoltage Electro-optic Catalysts

[0201] Example 3

[0202] Step S1: The (Bi) prepared in Example 1-1 0.95 Na 0.05 FeO3 was dissolved in an ethanol aqueous solution with a volume ratio of 50% to prepare a sol with a molar concentration of 0.2 mol / L. Polyvinylpyrrolidone K30 (PVP-K30) was gradually added to the sol at a volume molar ratio of 10 mL: 3.5 g to obtain a core material spinning precursor solution.

[0203] Step S2: Dissolve tetrabutyl titanate in ethanol solution to prepare a titanium source solution with a molar concentration of 0.2 mol / L; gradually add polyvinylpyrrolidone K30 (PVP-K30) to the titanium source solution at a volume molar ratio of 10 mL: 3.5 g to obtain a shell spinning precursor solution.

[0204] Step S3: Using coaxial electrospinning technology, the core material spinning precursor solution and the shell material spinning precursor solution are added to the solution through a coaxial spinning nozzle. The core layer flow rate is controlled at 0.1 mL / h and the shell layer flow rate is controlled at 0.2 mL / h. The distance from the nozzle to the receiving plate is controlled at 15 cm, and the spinning voltage is 20 kV. Coaxial spinning precursor nanofibers are prepared. The spinning precursor nanofibers are dried at 200℃ for 4 hours and sintered in a muffle furnace at 550℃ for 2 hours to obtain nanofibers with a multiferroic / photoelectric semiconductor core-shell structure, i.e., a magnetovoltage electrophotocatalyst.

[0205] Example 4

[0206] The preparation method of Example 4 is similar to that of Example 3, except that: in step S1 of Example 4, Bi(Fe) prepared in Example 2-1 is used. 0.9 Mn 0.1 O3 replaced the (Bi) prepared in Example 1-1 0.95 Na 0.05 )FeO3.

[0207] Comparative Example 2

[0208] The preparation method of Comparative Example 2 is similar to that of Example 3, except that in step S1 of Comparative Example 2, BiFeO3 prepared in Comparative Example 1 is used instead of (Bi)FeO3 prepared in Example 1-1. 0.95 Na 0.05 )FeO3.

[0209] The morphology and structure of the magneto-voltage electro-photocatalysts prepared in Examples 3-4 and Comparative Example 2 were characterized, and the results are as follows: Figure 4 As shown. Figure 4 (a) is a process flow diagram of preparing magnetovoltage electrophotocatalysts by electrospinning. Figure 4 b to g are scanning electron microscope (SEM) images, high-magnification SEM images, transmission electron microscope (TEM) images, selected area electron diffraction (SED) images, transmission electron microscope (TEM) images, and high-resolution transmission electron microscope (TEM) images of the magnetovoltage electro-optical catalyst prepared in Example 3, respectively. Figure 4 In the image, h to m represent the scanning electron microscope (SEM) image, high-magnification SEM image, transmission electron microscope (TEM) image, selected area electron diffraction (SED) image, transmission electron microscope (TEM) image, and high-resolution transmission electron microscope (TEM) image of the magnetovoltage electro-optical catalyst prepared in Example 4, respectively.

[0210] Depend on Figure 4 The results show that the magneto-voltage electro-photocatalyst has a one-dimensional nanostructure, while the Mn-doped bismuth ferrite material has a single-crystal structure.

[0211] The physical properties and catalytic performance of the magneto-voltage electro-optic catalysts of Examples 3-4 and Comparative Example 2 were characterized. The test results are as follows: Figure 5 As shown. Figure 5 In Figure 'a', the thermogravimetric-differential thermal curve of Comparative Example 2 is shown. Figure 5 In the figures b to e, the XRD patterns, hysteresis loops, N2 adsorption and desorption curves, and corresponding pore size distribution (dV / dD) curves of Examples 3-4 are respectively. Figure 5 f and i represent the magneto-electrocatalytic and magneto-voltage electro-photocatalytic degradation performance and kinetic analysis of Examples 3-4 and Comparative Example 2, respectively. Figure 5 The table below compares the catalytic degradation performance of undoped bismuth ferrite, Na-doped bismuth ferrite, Mn-doped bismuth ferrite, and the magnetovoltage electro-optic catalysts of Examples 3-4. Figure 5 The graph in the middle, k, represents a comparative analysis of magneto-voltage electro-photocatalytic performance.

[0212] Depend on Figure 5 As can be seen from point a, the optimal heat treatment temperature for the magnetovoltage electro-optic catalyst is 500℃. Figure 5 As shown in b, both perovskite and anatase structures exist simultaneously in magneto-voltage electro-photocatalysts. Figure 5 As can be seen from c to e, Mn doping can significantly improve magnetic properties and has a large specific surface area (67.8 μm). 2 g -1 ) and porosity (4.7 nm). (From) Figure 5 As can be seen from f to j, Mn-doped bismuth ferrite exhibits superior catalytic performance.

[0213] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0214] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A magneto-voltage electro-photocatalyst, characterized in that, include: The core material includes A-site doped bismuth ferrite material, B-site doped bismuth ferrite material, or AB-site co-doped bismuth ferrite material; A shell layer covering at least a portion of the surface of the core; the shell layer is made of TiO2; The chemical formula of the A-site doped bismuth ferrite material is (Bi 1-x Na x )FeO3, 0<x≤0.99; the chemical formula of the B-site doped bismuth ferrite material is Bi(FeO3, 0<x≤0.99). 1-y M y O3, 0 < y ≤ 0.99, M element includes one or more of Mn and Co; the chemical formula of the AB-site co-doped bismuth ferrite material is (Bi 1-a Na a (Fe) 1-b M b )O3, 0<a≤0.99, 0<b≤0.

99.

2. The magneto-voltage electro-photocatalyst as described in claim 1, characterized in that, Includes at least one of the following features: (1)0＜x≤0.2； (2)0＜y≤0.1； (3) 0 < a ≤ 0.2, 0 < b ≤ 0.1; (4) The mass ratio of the core to the shell is 1:(1-3); (5) The magneto-voltage electro-optic catalyst is in the form of nanofibers; Optionally, the diameter of the nanofiber-like magneto-electro-photocatalyst is 50 nm to 200 nm; (6) The A-site doped bismuth ferrite material, the B-site doped bismuth ferrite material, or the AB-site co-doped bismuth ferrite material are all single-phase rhombohedral perovskite structures.

3. A method for preparing a magneto-voltage electro-photocatalyst, characterized in that, Includes the following steps: Prepare a core spinning precursor solution containing a first thickener and A-site doped bismuth ferrite material, B-site doped bismuth ferrite material, or AB-site co-doped bismuth ferrite material; Preparation of shell spinning precursor solution containing titanium source and second thickener; The core material spinning precursor solution and the shell material spinning precursor solution are simultaneously subjected to coaxial electrospinning to prepare spinning precursor nanofibers. The spinning precursor nanofibers are subjected to a first drying treatment and a first sintering treatment to prepare the magneto-voltage electro-optic catalyst; The chemical formula of the A-site doped bismuth ferrite material is (Bi 1-x Na x )FeO3, 0<x≤0.99; the chemical formula of the B-site doped bismuth ferrite material is Bi(FeO3, 0<x≤0.99). 1-y M y O3, 0 < y ≤ 0.99, M element includes one or more of Mn and Co; the chemical formula of the AB-site co-doped bismuth ferrite material is (Bi 1-a Na a (Fe) 1-b M b )O3, 0<a≤0.99, 0<b≤0.99; The magneto-voltage electro-photocatalyst includes a core and a shell covering at least a portion of the surface of the core. The core is made of a material including the A-site doped bismuth ferrite material, the B-site doped bismuth ferrite material, or the AB-site co-doped bismuth ferrite material. The shell is made of TiO2.

4. The preparation method of the magneto-voltage electro-photocatalyst as described in claim 3, characterized in that, Includes at least one of the following conditions: (1) The titanium source includes one or more of tetrabutyl titanate and isopropyl titanate; (2) The process parameters for coaxial electrospinning include: the inlet flow rate of the core material spinning precursor solution is 0.1 mL / h-0.5 mL / h, the inlet flow rate of the shell material spinning precursor solution is 0.1 mL / h-0.5 mL / h, the distance from the nozzle to the receiving plate is 10cm-20cm, and the spinning voltage is 15kV-30kV. (3) The temperature of the first drying treatment is 100℃-300℃, and the time is 4h-24h; (4) The temperature of the first sintering treatment is 500℃-700℃ and the time is 2h-5h.

5. The preparation method of the magneto-voltage electro-photocatalyst as described in claim 3, characterized in that, The steps for preparing a core spinning precursor solution comprising a first thickener and A-site doped bismuth ferrite, B-site doped bismuth ferrite, or AB-site co-doped bismuth ferrite include: Prepare a sol containing the A-site doped bismuth ferrite material, the B-site doped bismuth ferrite material, or the AB-site co-doped bismuth ferrite material; The sol is mixed with the first thickener to prepare the core material spinning precursor solution; Optionally, the molar concentration of the sol is 0.2 mol / L, and the volume-to-mass ratio of the sol to the first thickener is 10 mL:(2-5) g; Optionally, the first thickener includes one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyvinyl alcohol.

6. The preparation method of the magneto-voltage electro-photocatalyst as described in claim 3, characterized in that, The steps for preparing a shell spinning precursor solution containing a titanium source and a second thickener include: Prepare a titanium source solution containing the titanium source; The titanium source solution is mixed with the second thickener to prepare the shell material spinning precursor solution; Optionally, the molar concentration of the titanium source solution is 0.2 mol / L, and the volume-to-mass ratio of the titanium source solution to the second thickener is 10 mL:(2-5) g; Optionally, the second thickener includes one or more of polyvinylpyrrolidone, polymethyl methacrylate, and polyvinyl alcohol.

7. The method for preparing the magneto-voltage electro-photocatalyst according to any one of claims 3 to 6, characterized in that, The preparation method of the A-site doped bismuth ferrite material includes: A first solution comprising a sodium source, a first iron source, and a first bismuth source is prepared; The first solution is subjected to a second drying process; The product obtained from the second drying treatment is subjected to a second sintering treatment to prepare the A-site doped bismuth ferrite material; Optionally, the sodium source includes at least one of sodium nitrate and sodium acetate; Optionally, the first iron source includes at least one of ferric nitrate and ferric chloride; Optionally, the first bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate; Optionally, the temperature of the second drying process is 100℃-300℃, and the time is 4h-24h; Optionally, the temperature of the second sintering treatment is 500℃-700℃, and the time is 2h-5h; Optionally, the solvent for the first solution is dimethylformamide.

8. The method for preparing the magneto-voltage electro-photocatalyst according to any one of claims 3 to 6, characterized in that, The preparation method of the B-site doped bismuth ferrite material includes: A second solution comprising a manganese source, a second iron source, and a second bismuth source is prepared. The second solution is subjected to a third drying process; The product obtained from the third drying process is subjected to a third sintering process to prepare the B-site doped bismuth ferrite material. Optionally, the manganese source includes at least one of manganese nitrate and manganese acetate; Optionally, the second iron source includes at least one of ferric nitrate and ferric chloride; Optionally, the second bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate; Optionally, the temperature of the third drying process is 100℃-300℃, and the time is 4h-24h; Optionally, the temperature of the third sintering treatment is 500℃-700℃, and the time is 2h-5h; Optionally, the solvent for the second solution is dimethylformamide.

9. The method for preparing the magneto-voltage electro-photocatalyst according to any one of claims 3 to 6, characterized in that, The preparation method of the AB-site co-doped bismuth ferrite material includes: A third solution containing a sodium source, a manganese source, a third iron source, and a third bismuth source is prepared; The third solution is subjected to a fourth drying process; The product obtained from the fourth drying treatment is subjected to a fourth sintering treatment to prepare the AB-site co-doped bismuth ferrite material; Optionally, the manganese source includes at least one of manganese nitrate and manganese acetate; Optionally, the sodium source includes at least one of sodium nitrate and sodium acetate; Optionally, the third iron source includes at least one of ferric nitrate and ferric chloride; Optionally, the third bismuth source includes one or more of bismuth nitrate, bismuth acetate, and bismuth sulfate; Optionally, the temperature of the fourth drying process is 100℃-300℃, and the time is 4h-24h; Optionally, the fourth sintering treatment is performed at a temperature of 500℃-700℃ for 2 hours to 5 hours. Optionally, the solvent of the third solution is dimethylformamide.

10. The application of the magnetic voltage electro-photocatalyst prepared by the preparation method of the magnetic voltage electro-photocatalyst according to any one of claims 1 to 2 and any one of claims 3 to 9 in magnetic voltage electro-photocatalysis.

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