Fe3O4 magnetic film and application thereof in electrocatalytic water splitting

Abstract

The application discloses a Fe3O4 magnetic film, which has a left-handed chiral structure or a right-handed chiral structure. The Fe3O4 magnetic film is prepared by an electrochemical epitaxial growth method. The application also provides application of the Fe3O4 magnetic film in electrocatalytic water decomposition. The Fe3O4 magnetic film disclosed by the application has the advantages of simple preparation method, no need of special equipment and harsh conditions, fast and easy process, strong controllability, easy realization of large-area preparation and large-scale production, and the like. The application also provides application of the magnetic Fe3O4 film as an anode oxygen evolution reaction catalytic material in the electrocatalytic water decomposition reaction, which can effectively improve the water decomposition oxygen evolution reaction efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of inorganic materials, in particular to a Fe3O4 magnetic film and its application in electrocatalytic water splitting. BACKGROUND

[0002] The overuse of fossil fuels has led to global energy crisis and environmental problems, and finding and using green new energy has become the only way for human society to develop. Hydrogen is an ideal clean energy with high energy density, and the preparation of hydrogen from water through electrocatalytic water splitting and its use is an effective measure to solve the energy crisis and environmental problems. Domestic and foreign research shows that the reasons for the low efficiency of electrocatalytic water splitting are as follows: on the one hand, the high kinetic potential barrier of the anode oxygen evolution reaction and the slow kinetic rate of the anode oxygen evolution reaction reduce the overall efficiency of water splitting, resulting in a low rate of hydrogen evolution reaction at the cathode, which becomes one of the bottlenecks of water splitting reaction; on the other hand, during the anode oxygen evolution reaction, by-products such as peroxide and superoxide are often produced in the reaction system, which will be adsorbed on the surface of the electrocatalytic material, corroding and poisoning the electrocatalytic material, reducing its activity and life, and leading to a decrease in the efficiency of water splitting and high maintenance costs in the production process.

[0003] Due to the above problems, it is urgent to find an efficient, economical and scientific method that can reduce the kinetic potential barrier of the anode oxygen evolution reaction while preventing the formation of by-products such as hydrogen peroxide in the reaction system, and solve the bottleneck problems of these electrocatalytic water splitting reactions. In recent years, the ability of chiral substances and magnetic substances to regulate the carrier transport state has been valued, and research shows that chiral structures can cause cross-polarization of electromagnetic fields. In the process of anode oxygen evolution reaction, the anode catalytic material extracts electrons from water molecules, and when the electrons flow through the substance with chiral structure, they will be spin-polarized under the induction of the spiral electromagnetic field, and the intermediate product will also be spin-polarized, reducing the potential barrier of the formation of triplet oxygen molecules, which can improve the efficiency of electrocatalytic water splitting and inhibit the generation of by-products hydrogen peroxide. In addition, research has shown that in addition to chiral structures, magnetic substances also have the ability to regulate the carrier transport state of the material surface, which can improve the transport efficiency of carriers by spin-polarizing the carriers.

[0004] Currently, there are reports on anchoring organic chiral molecules on electrocatalytic materials to construct chiral structures and reduce the potential barrier of the anode oxygen evolution reaction of electrocatalytic water splitting. The disadvantages of organic chiral molecules are relatively high cost, poor conductivity, and stability affected by environmental factors such as pH, temperature, and salinity. Compared with organic chiral molecules, inorganic semiconductor chiral structure materials have low cost, high conductivity and stability, and can become high-quality and economical oxygen evolution catalysts for electrocatalytic water splitting. How to fix the inorganic chiral structure material on the conductive substrate and expose the catalytic active sites of the inorganic chiral structure material is a difficult problem. Currently, there are few cases of inorganic chiral structure materials as oxygen evolution catalysts for electrocatalytic water splitting in domestic and foreign research and application. In addition, there is no report on the use of magnetic inorganic chiral materials for electrocatalytic water splitting reaction in current domestic and foreign research and application. The reported chiral inorganic structure materials such as CuO do not have magnetism, and their chemical stability needs to be improved. SUMMARY

[0005] The purpose of the present application is to provide a Fe3O4 magnetic film which has a simple preparation method, does not require special equipment and harsh conditions, has a fast and easy process, strong controllability, and can be easily prepared in a large area and produced in large quantities, and the application of the above-mentioned magnetic Fe3O4 film as an anode oxygen evolution reaction catalyst material in the electrocatalytic water splitting reaction, which can effectively improve the efficiency of the water splitting oxygen evolution reaction.

[0006] Technical scheme: The present application provides a Fe3O4 magnetic film with left-handed or right-handed chiral structure.

[0007] The Fe3O4 magnetic film is prepared by electrochemical epitaxial growth method.

[0008] The present application also provides an electrochemical epitaxial growth method for Fe3O4 magnetic film, which comprises the following steps:

[0009] In an electrolyte containing chiral molecules, iron salt and base, a saturated mercury electrode is used as a reference electrode, a platinum black electrode is used as a counter electrode, a deposition substrate is used as a working electrode, a constant voltage is applied to the working electrode, and a Fe3O4 film is obtained by deposition growth.

[0010] Further, the preparation method of the electrolyte is as follows: the aqueous solution of chiral molecules is mixed with the aqueous solution of iron salt to make Fe 2+ ions complex with chiral molecules, then a base solution is added under ultrasonic action, ultrasonic dispersion is carried out, and the mixture is uniformly mixed to obtain an electrolyte.

[0011] Further, the chiral molecule is left-handed or right-handed tartaric acid with a concentration of 0.1 mol / L-0.2 mol / L.

[0012] Further, the iron salt is FeSO4·7H2O, and the concentration is 0.1 mol / L-0.2 mol / L.

[0013] Further, the base is NaOH, and the concentration is 0.12 mol / L-0.16 mol / L.

[0014] Further, the constant voltage is -1.2V ~ -1.5V, and the ultrasonic power of the ultrasonic action is 120W ~ 240W.

[0015] Further, the deposition growth time is 15s ~ 60s, and the deposition substrate is FTO glass.

[0016] The application further provides application of the Fe3O4 magnetic thin film in electrocatalytic water decomposition. Beneficial effects

[0017] The Fe3O4 has intrinsic magnetism, and the Fe3O4 magnetic thin film is prepared by using an electrochemical epitaxial growth method, in the deposition growth process of the thin film, chiral molecule induces orientation growth of reactant atoms and ions, chiral is transmitted from the organic molecule to the Fe3O4 magnetic inorganic metal oxide thin film, structure assembly and accurate construction of the magnetic inorganic chiral metal oxide are realized, and the Fe3O4 magnetic thin film with left-handed chiral structure or right-handed chiral structure is formed.

[0018] The Fe3O4 magnetic thin film provided by the application utilizes the left-handed chiral structure or right-handed chiral structure of the metal oxide thin film and the intrinsic magnetism of the Fe3O4 magnetic thin film to the spin polarization of electrons, the chiral structure of the metal oxide thin film can cause cross polarization of an electromagnetic field, and the magnetic substance also has the regulation ability of regulating the carrier transport state of a material surface, when the electrons flow through the Fe3O4 magnetic thin film with the chiral structure, the electrons are spin polarized, the potential barrier of an anode oxygen evolution reaction is reduced, the transport efficiency of the carriers is improved, and the anode oxygen evolution reaction efficiency of the Fe3O4 magnetic thin film is improved.

[0019] The preparation method of the Fe3O4 magnetic thin film is simple, does not need special equipment and harsh conditions, can be completed within 60s, is fast and easy to operate, has strong controllability, and is easy to realize large-area preparation and large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings described herein are used to provide further understanding of the application, constitute a part of the application, and do not constitute improper limitations on the application, and in the drawings:

[0021] Figure 1is a chiral electrochemical scanning graph of the Fe3O4 magnetic thin film with a left-handed chiral structure of the embodiment 1 of the present application;

[0022] Figure 2 is a cross-polarization reflection graph of the Fe3O4 magnetic thin film with a left-handed chiral structure of the embodiment 1 of the present application;

[0023] Figure 3 is a linear voltammetry curve of the Fe3O4 magnetic thin film with a left-handed chiral structure of the embodiment 1 of the present application as an anode oxygen evolution catalytic material, participating in an electrocatalytic oxygen evolution reaction;

[0024] Figure 4 is a graph of the inhibition of the generation of a reaction by-product hydrogen peroxide by the Fe3O4 magnetic thin film with a left-handed chiral structure of the embodiment 1 of the present application;

[0025] Figure 5 is a chiral electrochemical scanning graph of the Fe3O4 magnetic thin film with a right-handed chiral structure of the embodiment 2 of the present application;

[0026] Figure 6 is a cross-polarization reflection graph of the Fe3O4 magnetic thin film with a right-handed chiral structure of the embodiment 2 of the present application;

[0027] Figure 7 is a linear voltammetry curve of the Fe3O4 magnetic thin film with a right-handed chiral structure of the embodiment 2 of the present application as an anode oxygen evolution catalytic material, participating in an electrocatalytic oxygen evolution reaction;

[0028] Figure 8 is a graph of the inhibition of the generation of a reaction by-product hydrogen peroxide by the Fe3O4 magnetic thin film with a right-handed chiral structure of the embodiment 2 of the present application;

[0029] Figure 9 is a chiral electrochemical scanning graph of the Fe3O4 magnetic thin film with a left-handed chiral structure of the embodiment 3 of the present application;

[0030] Figure 10 is a cross-polarization reflection graph of the Fe3O4 magnetic thin film with a left-handed chiral structure of the embodiment 3 of the present application;

[0031] Figure 11 is a linear voltammetry curve of the Fe3O4 magnetic thin film with a left-handed chiral structure of the embodiment 3 of the present application as an anode oxygen evolution catalytic material, participating in an electrocatalytic oxygen evolution reaction;

[0032] Figure 12 is a graph of the inhibition of the generation of a reaction by-product hydrogen peroxide by the Fe3O4 magnetic thin film with a left-handed chiral structure of the embodiment 3 of the present application.

[0033] Figure 13is a mechanism diagram of the present application using Fe3O4 magnetic film with chiral structure to reduce the potential barrier of electrocatalytic water decomposition oxygen evolution reaction and improve the reaction efficiency. Embodiment

[0034] In order to deepen the understanding of the present application, the present application will be further described below in combination with examples and drawings, which are only used to explain the present application and do not constitute a limitation on the protection scope of the present application.

[0035] Figure 13 is a mechanism diagram of embodiments 1-3 of the present application using the spin polarization characteristics of the left-handed chiral structure of Fe3O4 magnetic film to improve the oxygen reduction performance.

[0036] As shown in Figure 13 , the left-handed chiral structure of the Fe3O4 magnetic film in the following embodiments can cause cross polarization of electromagnetic field, the electron flow through the Fe3O4 magnetic film with left-handed chiral structure is spin-polarized, the potential barrier of electron reduction of oxygen is reduced, and the oxygen reduction efficiency of the Fe3O4 magnetic film is improved. Embodiment

[0037] The preparation of the Fe3O4 magnetic film with left-handed chiral structure is as follows:

[0038] In the electrolyte, a saturated calomel electrode is used as a reference electrode, a platinum black electrode is used as a counter electrode, and an FTO glass is used as a working electrode. A constant voltage of-1.5V is applied to the working electrode, and the deposition time is 30s. In the deposition and growth process of the film, the left-handed chiral molecules in the electrolyte induce the oriented growth of reactant atoms and ions. After a period of deposition and growth, the Fe3O4 magnetic film with left-handed chiral structure is obtained.

[0039] The electrolyte is a mixed solution of left-handed chiral tartaric acid, FeSO4·7H2O and NaOH, and the solvent is deionized water. The concentration of chiral tartaric acid is 0.1mol / L, the concentration of FeSO4·7H2O is 0.2mol / L, and the concentration of NaOH is 0.12mol / L. First, the left-handed chiral tartaric acid aqueous solution and the FeSO4·7H2O aqueous solution are mixed uniformly to complex Fe 2+ ions with chiral tartaric acid molecules, and then the NaOH solution is added under the action of 120W ultrasonic and mixed uniformly.

[0040] The chiral electrochemical scanning diagram of the Fe3O4 magnetic film with left-handed chiral structure provided in the present embodiment is shown in Figure 1 ; its orthogonal polarized light reflection diagram is shown in Figure 2 ; its linear voltammetry curve as an anode oxygen evolution reaction catalytic material participating in electrocatalytic oxygen evolution reaction is shown in Figure 3 ; and its inhibition effect on the generation of reaction byproduct hydrogen peroxide is shown in .Figure 4 As shown.

[0041] In the chiral electrochemical scanning process, the electrolyte contains a low concentration of L-tartaric acid or D-tartaric acid, and argon is bubbled into the electrolyte until saturation. As shown in Figure 1 , the L-tartaric acid (10 mM) in the electrolyte has a high electrochemical signal, and the electrochemical signal of D-tartaric acid (10 mM) is weak, indicating that the interaction between the prepared Fe3O4 magnetic thin film and L-tartaric acid is strong, which is mainly due to the selective recognition of the Fe3O4 magnetic thin film with left-handed chiral structure to L-tartaric acid.

[0042] As shown in Figure 2 , under orthogonal polarized light conditions, the surface of the Fe3O4 magnetic thin film with left-handed chiral structure presents a texture morphology.

[0043] In 0.1M KOH solution, argon is bubbled until saturation. The linear sweep voltammetry curve of the water decomposition and oxygen evolution of the Fe3O4 magnetic thin film with left-handed chiral structure is shown in Figure 3 , and the linear sweep voltammetry scanning rate is 50 mV / s. As can be seen from Figure 3 , compared with the Fe3O4 magnetic thin film without chiral structure, the starting oxygen evolution potential of the Fe3O4 magnetic thin film with left-handed chiral structure is lower than that of the Fe3O4 magnetic thin film without chiral structure; in addition, the potential of the Fe3O4 magnetic thin film without chiral structure is 1.157V at the oxygen evolution reaction current of 10 mA / cm 2 , and the potential of the Fe3O4 magnetic thin film with left-handed chiral structure is 0.995V at the oxygen evolution reaction current of 10 mA / cm 2 , which is reduced by about 162 mV; its oxygen evolution reaction current at 1.8V (vs SCE) increases from 23.3mA to 33.0mA, an increase of about 42%. This indicates that the oxygen evolution reaction is easier to occur on the surface of the Fe3O4 magnetic thin film with left-handed chiral structure compared with the Fe3O4 magnetic thin film without chiral structure, and the Fe3O4 magnetic thin film with left-handed chiral structure reduces the potential barrier of anode oxygen evolution reaction, improves the carrier transport efficiency and anode oxygen evolution reaction efficiency.

[0044] The formation of hydrogen peroxide, a byproduct in the reaction system, was tested by color development method. The higher the concentration of hydrogen peroxide, the stronger the color development peak. As can be seen from Figure 4 , compared with the Fe3O4 magnetic thin film without chiral structure, the formation of hydrogen peroxide byproduct in the reaction system of the Fe3O4 magnetic thin film with left-handed chiral structure is inhibited. Example

[0045] The preparation of the Fe3O4 magnetic thin film with right-handed chiral structure is as follows:

[0046] In the electrolyte, a saturated calomel electrode was used as the reference electrode, a platinum black electrode as the counter electrode, and FTO glass as the working electrode. A constant voltage of -1.5V was applied to the working electrode, and the deposition time was 30s. During the deposition and growth of the thin film, the dextrorotatory chiral molecules in the electrolyte induced the orientation and growth of reactant atoms and ions. After a period of deposition and growth, a Fe3O4 magnetic thin film with a dextrorotatory chiral structure was obtained.

[0047] The electrolyte is a mixed solution of dextrorotatory chiral tartaric acid, FeSO4·7H2O, and NaOH, with deionized water as the solvent; the concentrations of chiral tartaric acid, FeSO4·7H2O, and NaOH are 0.1 mol / L and 0.16 mol / L, respectively. First, the aqueous solution of dextrorotatory chiral tartaric acid and the aqueous solution of FeSO4·7H2O are mixed thoroughly to ensure the Fe... 2+ The ions complex with the chiral tartaric acid molecules, and then NaOH solution is added under 120W ultrasonic treatment and mixed evenly.

[0048] The chiral electrochemical scanning image of the Fe3O4 magnetic thin film with a dextrorotatory chiral structure provided in this embodiment is as follows: Figure 5 As shown; its orthogonally polarized light reflection pattern is as follows Figure 6 As shown; its linear voltammetric curve for participating in the electrocatalytic oxygen evolution reaction as an anodic oxygen evolution reaction catalyst is shown in the figure. Figure 7 As shown; its inhibitory effect on the formation of hydrogen peroxide, a byproduct of the reaction, is as follows: Figure 8 As shown.

[0049] During the chiral electrochemical scanning process, the electrolyte used contains a low concentration of L-tartaric acid or D-tartaric acid, and oxygen is bubbled into the electrolyte until saturation. Figure 5 It is evident that D-tartaric acid (concentration of 10 mM) in the electrolyte exhibits a high electrochemical signal, while L-tartaric acid (concentration of 10 mM) shows a weaker electrochemical signal. This indicates a strong interaction between the prepared Fe3O4 magnetic film and D-tartaric acid, which is mainly due to the selective recognition of D-tartaric acid by the Fe3O4 magnetic film with its dextrorotatory chiral structure.

[0050] like Figure 6 As shown, under crossed polarization conditions, the surface of Fe3O4 magnetic thin films with a right-handed chiral structure exhibits a textured morphology.

[0051] Argon gas was bubbled into a 0.1 M KOH solution until saturation. The linear sweep voltammetric curves for moisture desorption and oxygen resorption of Fe3O4 magnetic thin films with a dextrorotatory chiral structure are shown below. Figure 7 As shown, the linear voltammetry curve scan rate is 50 mV / s.

[0052] from Figure 7 It is evident that, compared to Fe3O4 magnetic films without chiral structures, Fe3O4 magnetic films with dextrorotatory chiral structures have a lower initial oxygen evolution potential. Furthermore, the Fe3O4 magnetic films without chiral structures exhibit a lower initial oxygen evolution potential at an oxygen evolution reaction current of 10 mA / cm². 2 The potential at the point is 1.157V. The Fe3O4 magnetic thin film with a dextrorotatory chiral structure exhibits a potential of 1.157V during the oxygen evolution reaction at a current of 10mA / cm². 2 The potential at the anodic oxygen evolution reaction (OER) is 1.010 V, a decrease of approximately 162 mV; the OER current at 1.8 V (vs SCE) increases from 23.3 mA to 32.6 mA, an increase of approximately 40%. This indicates that compared to Fe3O4 magnetic films without chiral structures, the OER is more readily generated on the surface of Fe3O4 magnetic films with dextrorotatory chiral structures. The dextrorotatory chiral structure of Fe3O4 magnetic films lowers the potential barrier for the anodic OER, thereby improving both carrier transport efficiency and anodic OER efficiency.

[0053] The formation of hydrogen peroxide, a byproduct, in the reaction system was tested using a colorimetric method. Higher hydrogen peroxide concentrations resulted in stronger colorimetric peaks. Figure 8 It is evident that, compared to Fe3O4 magnetic films without chiral structures, the formation of hydrogen peroxide byproducts is suppressed in the reaction system of Fe3O4 magnetic films with right-handed structures. Example

[0054] The preparation steps of Fe3O4 magnetic thin films with a left-handed chiral structure are as follows:

[0055] In the electrolyte, a saturated calomel electrode was used as the reference electrode, a platinum black electrode as the counter electrode, and FTO glass as the working electrode. A constant voltage of -1.2V was applied to the working electrode, and the deposition time was 60s. During the deposition and growth of the thin film, the left-handed chiral molecules in the electrolyte induced the orientation and growth of reactant atoms and ions. After a period of deposition and growth, a Fe3O4 magnetic thin film with a left-handed chiral structure was obtained.

[0056] The electrolyte is a mixed solution of levorotatory chiral tartaric acid, FeSO4·7H2O, and NaOH, with deionized water as the solvent; the concentrations of chiral tartaric acid, FeSO4·7H2O, and NaOH are 0.2 mol / L and 0.12 mol / L, respectively. First, the aqueous solution of levorotatory chiral tartaric acid and the aqueous solution of FeSO4·7H2O are mixed thoroughly to ensure the Fe... 2+ The ions complex with the chiral tartaric acid molecules, and then NaOH solution is added under 240W ultrasonic treatment and mixed evenly.

[0057] The chiral electrochemical scanning graph of the Fe3O4 magnetic thin film with left-handed chiral structure provided by the embodiment is as shown in Figure 9 The orthogonal polarized light reflection graph of the Fe3O4 magnetic thin film with left-handed chiral structure is as shown in Figure 10 The linear voltammetry curve of the Fe3O4 magnetic thin film with left-handed chiral structure as an anode oxygen evolution reaction catalytic material participating in the electrocatalytic oxygen evolution reaction is as shown in Figure 11 The inhibition effect of the Fe3O4 magnetic thin film with left-handed chiral structure on the generation of the reaction byproduct hydrogen peroxide is as shown in Figure 12

[0058] In the chiral electrochemical scanning process, the electrolyte contains a low concentration of L-tartaric acid or D-tartaric acid, and argon is introduced into the electrolyte until saturation. As shown in Figure 9 The L-tartaric acid (10 mM) in the electrolyte has a high electrochemical signal, and the electrochemical signal of the D-tartaric acid (10 mM) is weak, which indicates that the interaction between the prepared Fe3O4 magnetic thin film and the L-tartaric acid is strong, which is mainly due to the selective recognition of the Fe3O4 magnetic thin film with left-handed chiral structure to the L-tartaric acid.

[0059] Under the condition of orthogonal polarized light, the surface of the Fe3O4 magnetic thin film with right-handed chiral structure presents a texture morphology, as shown in Figure 10

[0060] In 0.1M KOH solution, argon is introduced until saturation. The linear sweep voltammetry curve of the Fe3O4 magnetic thin film with left-handed chiral structure for water decomposition and oxygen evolution is as shown in Figure 11 The linear sweep voltammetry scanning rate is 50 mV / s.

[0061] As can be seen from Figure 11 Compared with the Fe3O4 magnetic thin film without chiral structure, the starting oxygen evolution potential of the Fe3O4 magnetic thin film with left-handed chiral structure is lower than that of the Fe3O4 magnetic thin film without chiral structure; in addition, the potential of the Fe3O4 magnetic thin film without chiral structure is 1.157V when the oxygen evolution reaction current is 10 mA / cm 2 The potential of the Fe3O4 magnetic thin film with left-handed chiral structure is 1.016V when the oxygen evolution reaction current is 10 mA / cm 2 , which is reduced by about 141 mV; the oxygen evolution reaction current of the Fe3O4 magnetic thin film with left-handed chiral structure increases from 23.3 mA to 30.4 mA at 1.8V (vs SCE), which is increased by about 30%. This indicates that the oxygen evolution reaction is more likely to occur on the surface of the Fe3O4 magnetic thin film with left-handed chiral structure compared with the Fe3O4 magnetic thin film without chiral structure, the Fe3O4 magnetic thin film with left-handed chiral structure reduces the potential barrier of the anode oxygen evolution reaction, and improves the carrier transport efficiency and the anode oxygen evolution reaction efficiency.

[0062] ​​The formation of the by-product hydrogen peroxide in the reaction system is tested by a colorimetric method. The higher the concentration of hydrogen peroxide is, the stronger the colorimetric peak is. From the colorimetric peak, it can be seen that the formation of hydrogen peroxide in the reaction system of the Fe3O4 magnetic film with the left-handed chiral structure is inhibited. Figure 12 It can be seen that, compared with the Fe3O4 magnetic film without chiral structure, the formation of hydrogen peroxide by-product in the reaction system of the Fe3O4 magnetic film with the left-handed chiral structure is inhibited.

[0063] The above merely describes preferred embodiments of the present application, and equivalent changes or modifications made to the structure, features and principles described in the patent application scope of the present application are included in the patent application scope of the present application.

Claims

1. The application of a Fe3O4 magnetic thin film in electrocatalytic water splitting, characterized in that, The Fe3O4 has a left-handed or right-handed chiral structure, which can lower the barrier to the anodic oxygen evolution reaction. The Fe3O4 magnetic thin film is prepared by electrochemical epitaxial growth.

2. The application of the Fe3O4 magnetic thin film according to claim 1 in electrocatalytic water splitting, characterized in that, The electrochemical epitaxial growth method includes the following steps: In an electrolyte containing chiral molecules, iron salts, and alkali, a saturated calomel electrode is used as the reference electrode, a platinum black electrode as the counter electrode, and a deposition substrate as the working electrode. A constant voltage is applied to the working electrode, and Fe3O4 thin films are deposited and grown.

3. The application of the Fe3O4 magnetic thin film according to claim 2 in electrocatalytic water splitting, characterized in that, The electrolyte is prepared by mixing an aqueous solution of chiral molecules with an aqueous solution of iron salt, so that Fe... 2+ Ions are complexed with chiral molecules, and then an alkaline solution is added under ultrasonication. The mixture is then ultrasonically dispersed and homogenized to obtain an electrolyte.

4. The application of the Fe3O4 magnetic thin film according to claim 2 in electrocatalytic water splitting, characterized in that, The chiral molecule is either levorotatory chiral tartaric acid or dextrorotatory chiral tartaric acid, with a concentration of 0.1 mol / L to 0.2 mol / L.

5. The application of the Fe3O4 magnetic thin film according to claim 2 in electrocatalytic water splitting, characterized in that, The iron salt is FeSO4·7H2O, with a concentration of 0.1 mol / L to 0.2 mol / L.

6. The application of the Fe3O4 magnetic thin film according to claim 2 in electrocatalytic water splitting, characterized in that, The alkali is NaOH with a concentration of 0.12 mol / L to 0.16 mol / L.

7. The application of the Fe3O4 magnetic thin film according to claim 3 in electrocatalytic water splitting, characterized in that, The Fe3O4 magnetic thin film is characterized in that the constant voltage is -1.2V to -1.5V and the ultrasonic power of the ultrasonic action is 120W to 240W.

8. The application of the Fe3O4 magnetic thin film according to claim 2 in electrocatalytic water splitting, characterized in that, The deposition growth time is 15s to 60s, and the deposition substrate is FTO glass.

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