A vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst, its preparation method and application

Abstract

This invention relates to a vacancy-controlled manganese selenide-molybdenum selenide-sulfurite heterojunction catalyst, its preparation method, and its applications. The invention first prepares nanoparticle-sized MnSe, then reacts the MnSe with sodium molybdate, Se powder, and other raw materials via a hydrothermal reaction to obtain the manganese selenide-molybdenum selenide-sulfurite heterojunction catalyst. Further, Mn vacancies are introduced according to different performance requirements. Vacancy-introducing agents include ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylene phosphate, and hexametaphosphate, ultimately yielding the vacancy-controlled manganese selenide-molybdenum selenide-sulfurite heterojunction catalyst. The vacancy-controlled manganese selenide-molybdenum selenide-sulfurite heterojunction catalyst exhibits significantly enhanced photoelectrochemical and electrocatalytic performance; its photocurrent density is 5.2 times that of single-electrochemical MoSSe, and the electrocatalytic hydrogen evolution overpotential is reduced to 197 mV compared to MoSSe's 476 mV. The method of this invention is simple, easy to control, and has high production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, and relates to a vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst, its preparation method, and its application. Background Technology

[0002] Manganese selenide (MnSe) is a catalytic material with a narrow band gap (around 1.1 eV) and good absorption of visible light. Molybdenum selenide (MoSSe) is a two-dimensional nanomaterial with a band gap of around 1.5 eV and good carrier transport properties. Studies have shown that constructing catalysts with heterojunction structures can improve the separation rate of photogenerated electrons and holes within a single catalyst material, thereby overcoming the shortcomings of traditional single catalyst materials in terms of catalytic activity. Furthermore, controlling the formation of metal or non-metal vacancies can create catalytic reaction sites on the catalyst surface, increasing the activity of catalytic reactions such as hydrogen evolution.

[0003] No vacancy-controlled manganese selenide-molybdenum selenide sulfide heterojunction catalysts have been reported. The applicant found that this is mainly due to the high internal resistance and low internal carrier separation and transport efficiency of MnSe alone, while MoSSe has good carrier transport capabilities. If MnSe and MoSSe are combined to form a heterojunction and vacancies are introduced, it is expected to simultaneously achieve good photoelectrocatalytic and electrocatalytic water splitting performance. However, nano-sized MnSe is metastable in hydrothermal environments and is prone to decomposition or phase transition. Furthermore, the synthesis conditions of MnSe and MoSSe differ significantly, making it difficult to obtain a composite material that integrates these two nanomaterials. Controlling the formation of Mn vacancies is also quite challenging, as vacancy formation is related to vacancy energy; generally, the smaller the ionic radius, the smaller the vacancy energy, and the easier it is to form vacancies. In selenides, because the ionic radius of non-metallic selenium is generally smaller than that of metal ions, Se vacancies are easily formed, while metal vacancies (such as Mn vacancies) are less likely to form. In addition, vacancy stability and the compatibility of vacancy formation conditions with the processes of the two catalysts must also be considered.

[0004] Therefore, this invention provides a mature and reliable method for preparing vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalysts and studies their applications in photoelectrochemistry and electrocatalytic water splitting. Summary of the Invention

[0005] One objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst that can improve the photoelectrochemical and electrocatalytic performance of traditional single catalysts.

[0006] The technical solution provided by this invention to solve the above-mentioned technical problems is as follows:

[0007] This invention first prepares nanoparticle-sized MnSe, then adds sodium molybdate, Se powder, sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium sulfide, ethanol, and water to the nanoparticle-sized MnSe. A hydrothermal reaction yields a manganese selenide-molybdenum selenide heterojunction catalyst. Further, Mn vacancies are introduced according to different performance requirements. Vacancy-introducing agents include ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylenephosphonate, and hexametaphosphate. The specific steps include:

[0008] Step (1): MnCl2 . 4H2O, sodium borohydride, selenium powder, sodium cetylbenzenesulfonate, stearyl alcohol and water were mixed in a molar ratio of 1:(2-3):(1-2):(2-3):(1-2):60 and placed in a hydrothermal reactor for hydrothermal reaction.

[0009] Preferably, the hydrothermal reaction temperature is 160–200℃, and the constant temperature time is 16–20 hours.

[0010] MnCl2 is preferred. . 4H2O, sodium borohydride, selenium powder, sodium hexadecylbenzenesulfonate, stearyl alcohol and water are in a ratio of 1:2:1:2:2:60;

[0011] Step (2): The solid-liquid mixture after hydrothermal reaction is separated by solid-liquid centrifugation. The solid product is taken out and washed alternately with deionized water and alcohol. It is then dried at 70-80℃ for 4-6 hours and ground into powder to obtain nano-particle MnSe.

[0012] Step (3): Mix the above-mentioned nano-particles of MnSe, sodium molybdate, Se powder, sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol and water in a molar ratio of 10:(1-3):(1-3):(4-6):(2-4):(1-3):(1-3):(1-3):30:30 to form a precursor solution, and place it in a hydrothermal reactor for hydrothermal reaction; wherein the hydrothermal reaction temperature is 160-200℃ and the constant temperature time is 18-24 hours;

[0013] Preferably, the ratio of nanoparticles MnSe, sodium molybdate, Se powder, sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol and water is 10:2:2:5:3:2:2:2:30:30;

[0014] Step (4): After the hydrothermal reaction, the solid-liquid mixture is centrifuged to separate the liquid product, and the solid product is taken out. It is washed three times with deionized water and alcohol, and then dried at 70-80°C for 4-6 hours. It is then ground into powder to obtain manganese selenide-molybdenum selenide heterojunction catalyst.

[0015] Step (5): Manganese selenide-molybdenum selenide heterojunction, ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylenephosphonate, and hexametaphosphate are mixed in a certain molar ratio of 20:(1-3):(1-3):(2-4):(2-4):(1-3):(1-3), and heated in a beaker to obtain a solid-liquid mixture, i.e., a vacancy catalyst; wherein the reaction temperature is 50-80℃ and the reaction time is 1-3 hours;

[0016] As a preferred embodiment, the ratio of manganese selenide-molybdenum selenide heterojunction, ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylenephosphonate, and hexametaphosphate is 20:2:2:3:3:2:2, the reaction temperature is 60℃, and the reaction time is 2 hours.

[0017] Step (6): The solid-liquid mixture after reaction is centrifuged to separate the liquid product and the solid product. The solid product is then washed three times with deionized water and alcohol, dried at 70-80°C for 4-6 hours, and ground into powder to obtain the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst.

[0018] Another object of the present invention is to provide a vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst, prepared by the above method, comprising a MoSSe matrix, MnSe supported on the MoSSe, and vacancies formed on the MnSe.

[0019] Another objective of this invention is to provide an application of a vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst as a photoelectrocatalyst.

[0020] Another objective of this invention is to provide an application of a vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst as an electrocatalyst.

[0021] Preferably, the vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst is used for photoelectrochemical and electrocatalytic water splitting.

[0022] The beneficial effects of this invention are:

[0023] This invention uses MnCl2 .Nanoparticle-sized MnSe was prepared using 4H₂O, sodium borohydride, selenium powder, sodium hexadecylbenzenesulfonate, stearyl alcohol, and water. Its nanoparticle structure facilitates composite formation with two-dimensional nanosheet-like MoSSe. Two-dimensional nanosheet-like MoSSe was prepared using MnSe, sodium molybdate, Se powder, sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol, and water as precursors. The addition of sodium hexadecylbenzenesulfonate reduced the size of the MnSe nanoparticles, while stearyl alcohol formed a protective coating on the MnSe surface, preventing dissolution in the hydrothermal environment and ensuring stability during the composite process. Sodium benzoate protected MoSSe and prevented its growth. Alcohol increased the solubility of several surfactants, increased the hydrothermal reaction pressure, refined the particles, and improved its crystallinity. Furthermore, the two-dimensional sheet-like MoSSe nanomaterials possess a large specific surface area, providing a three-dimensional network structure to load MnSe, which is beneficial for collecting charge carriers on MnSe and improving carrier transport efficiency.

[0024] This invention uses ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylenephosphonate, and hexametaphosphate as vacancy introducers and stabilizers to control the generation of Mn vacancies on MnSe. These vacancies serve as reactive sites on the one hand, and improve carrier transport efficiency on the other, which is beneficial to improving catalytic activity.

[0025] This invention also provides the application of the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst described in the above technical solution or the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst prepared by the preparation method described in the above technical solution in photoelectrochemistry and electrocatalysis.

[0026] In this invention, the vacancy-controlled manganese selenide-molybdenum selenide sulfide heterojunction catalyst can generate photogenerated electron-hole pairs under visible light. The photogenerated electrons transfer from the conduction band of MnSe to the conduction band of MoSSe, thereby achieving carrier separation. The vacancies on MnSe become active centers for the hydrogen evolution reaction. In this way, the catalyst exhibits good photoelectric efficiency and hydrogen evolution activity, as well as higher photoelectrochemical and electrocatalytic performance. Attached Figure Description

[0027] Figure 1 The image shows a scanning electron microscope (SEM) image of the manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 1.

[0028] Figure 2 Transmission electron microscopy (TEM) image of the vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 2;

[0029] Figure 3X-ray diffraction (XRD) patterns of the manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 1 and 3, the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 2 and 4, and MnSe and MoSSe.

[0030] Figure 4 The images show the UV-Vis absorption spectra of the manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 1 and 3, the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 2 and 4, and MnSe and MoSSe.

[0031] Figure 5 The vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 4 and the specific surface area nitrogen adsorption diagram (BET) of MnSe and MoSSe.

[0032] Figure 6 The pore size distribution diagrams of the vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 4 and MnSe and MoSSe are shown.

[0033] Figure 7 Fluorescence spectra of vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 2 and 4, and MnSe and MoSSe.

[0034] Figure 8 Electron paramagnetic spectra of the manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 3 and the vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 4.

[0035] Figure 9 The images show the manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 1 and 3, the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 2 and 4, and the electrocatalytic hydrogen evolution diagrams of MnSe and MoSSe.

[0036] Figure 10 Manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 1 and 3, and photoelectrochemical hydrogen evolution diagrams of MnSe and MoSSe;

[0037] Figure 11 Manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 1 and 3, and their unbiased photocurrent diagrams. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the invention is not limited to the scope of the embodiments described herein.

[0039] Example 1:

[0040] MnCl2 .4H₂O, sodium borohydride, selenium powder, sodium hexadecylbenzenesulfonate, stearyl alcohol, and water were mixed in a molar ratio of 1:2:1:2:1:60 and placed in a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature was 160℃, and the constant temperature time was 16 hours. The solid-liquid mixture after the hydrothermal reaction was centrifuged to separate the liquid product. The solid product was taken out, washed three times alternately with deionized water and alcohol, and then dried at 70℃ for 4 hours. The dried product was ground into powder to obtain nano-particle MnSe. The above nano-particle MnSe, sodium molybdate, and Se powder were then combined. Sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol, and water were mixed in a molar ratio of 10:1:1:4:2:1:1:1:30:30 to form a precursor solution, which was then placed in a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature was 160℃, and the constant temperature time was 18 hours. The solid-liquid mixture after the hydrothermal reaction was centrifuged to separate the liquid product, and the solid product was taken out and washed three times alternately with deionized water and alcohol, and then dried at 70℃ for 4 hours. The dried product was ground into powder to obtain a manganese selenide-molybdenum selenide heterojunction catalyst.

[0041] Figure 1 The image shows a scanning electron microscope (SEM) image of the manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 1. It can be seen that the nanoparticles of MnSe and MoSSe are uniformly distributed in the manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 1.

[0042] Example 2:

[0043] MnCl2 .4H₂O, sodium borohydride, selenium powder, sodium hexadecylbenzenesulfonate, stearyl alcohol, and water were mixed in a certain molar ratio of 1:2:1:2:1:60 and placed in a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature was 160℃, and the constant temperature time was 16 hours. The solid-liquid mixture after the hydrothermal reaction was centrifuged to separate the liquid product and remove the solid product. The solid product was washed three times alternately with deionized water and alcohol and then dried at 70℃ for 4 hours. The dried product was ground into powder to obtain nano-particle MnSe. The above nano-particle MnSe, sodium molybdate, and Se powder were then combined. Sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol, and water were mixed in a certain molar ratio of 10:1:1:4:2:1:1:1:30:30 to form a precursor solution, which was then placed in a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature was 160℃, and the constant temperature time was 18 hours. The solid-liquid mixture after the hydrothermal reaction was centrifuged to separate the liquid product, and the solid product was taken out and washed three times alternately with deionized water and alcohol, and then dried at 70℃ for 4 hours. The dried product was ground into powder to obtain a manganese selenide-molybdenum selenide heterojunction catalyst. Manganese selenide-molybdenum selenide heterojunction, ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylenephosphonate, and hexametaphosphate were mixed in a certain molar ratio of 20:1:1:2:2:1:1 and placed in a beaker for heating to form a vacancy catalyst. The reaction temperature was 50℃ and the reaction time was 1 hour. The solid-liquid mixture after the reaction was centrifuged to separate the liquid and solid products. The liquid product was poured out and the solid product was taken out and washed three times alternately with deionized water and alcohol, and then dried at 70℃ for 4 hours. The dried product was ground into powder to obtain the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst.

[0044] Figure 2 The image shows a transmission electron microscope (TEM) image of the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 2. It can be seen that the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 2 has a good composite structure, wherein the lattice spacing of 0.276 nm corresponds to the (200) plane of MnSe and the lattice spacing of 0.655 nm corresponds to the (002) plane of MoSSe.

[0045] Example 3:

[0046] MnCl2 .4H₂O, sodium borohydride, selenium powder, sodium hexadecylbenzenesulfonate, stearyl alcohol, and water were mixed in a certain molar ratio of 1:3:2:3:2:60 and placed in a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature was 200℃, and the constant temperature time was 20 hours. The solid-liquid mixture after the hydrothermal reaction was centrifuged to separate the liquid product and remove the solid product. The solid product was washed three times alternately with deionized water and alcohol and then dried at 80℃ for 6 hours. The dried product was ground into powder to obtain nano-particle MnSe. The above nano-particle MnSe, sodium molybdate, and Se powder were then combined. Sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol, and water were mixed in a certain molar ratio of 10:3:3:6:4:3:3:3:30:30 to form a precursor solution, which was then placed in a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature was 200℃, and the constant temperature time was 24 hours. The solid-liquid mixture after the hydrothermal reaction was centrifuged to separate the liquid and solid products. The liquid product was poured out, and the solid product was taken out and washed three times alternately with deionized water and alcohol, and then dried at 80℃ for 6 hours. The dried product was ground into powder to obtain a manganese selenide-molybdenum selenide heterojunction catalyst.

[0047] Example 4:

[0048] MnCl2 .4H₂O, sodium borohydride, selenium powder, sodium hexadecylbenzenesulfonate, stearyl alcohol, and water were mixed in a certain molar ratio of 1:3:2:3:2:60 and placed in a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature was 200℃, and the constant temperature time was 20 hours. The solid-liquid mixture after the hydrothermal reaction was centrifuged to separate the liquid product and remove the solid product. The solid product was washed three times alternately with deionized water and alcohol and then dried at 80℃ for 6 hours. The dried product was ground into powder to obtain nano-particle MnSe. The above nano-particle MnSe, sodium molybdate, and Se powder were then combined. Sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol, and water were mixed in a certain molar ratio of 10:3:3:6:4:3:3:3:30:30 to form a precursor solution, which was then placed in a hydrothermal reactor for hydrothermal reaction. The hydrothermal reaction temperature was 200℃, and the constant temperature time was 24 hours. The solid-liquid mixture after the hydrothermal reaction was centrifuged to separate the liquid and solid products. The liquid product was poured out, and the solid product was taken out and washed three times alternately with deionized water and alcohol, and then dried at 80℃ for 6 hours. The dried product was ground into powder to obtain a manganese selenide-molybdenum selenide heterojunction catalyst. Manganese selenide-molybdenum selenide heterojunction, ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylenephosphonate, and hexametaphosphate were mixed in a certain molar ratio of 20:3:3:4:4:3:3 and placed in a beaker for heating to form a vacancy catalyst. The reaction temperature was 80℃ and the reaction time was 3 hours. The solid-liquid mixture after the reaction was centrifuged to separate the liquid and solid products. The liquid product was poured out and the solid product was taken out and washed three times alternately with deionized water and alcohol, and then dried at 80℃ for 6 hours. The dried product was ground into powder to obtain the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst.

[0049] Figure 3 The X-ray diffraction (XRD) patterns of the manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 1 and 3, the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 2 and 4, and MnSe and MoSSe are shown. It can be seen that the main diffraction peaks of the products obtained in Examples 1-4 are close to the peak positions of the MoSSe substrate, indicating good crystallinity.

[0050] Figure 4 The UV-Vis absorption spectra of the manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 1 and 3, the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 2 and 4, and MnSe and MoSSe can be seen. It can be seen that the products obtained in Examples 1-4 have good light absorption in the UV-Vis band.

[0051] Figure 5The nitrogen adsorption diagram (BET) of the vacancy-controlled manganese selenide-molybdenum selenide-sulfuride heterojunction catalyst prepared in Example 4, along with MnSe and MoSSe, shows that its specific surface area is 16.9 m². 2 / g.

[0052] Figure 6 The images show the pore size distributions of the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 4, as well as MnSe and MoSSe. Their pore size distributions are similar to those of MoSSe.

[0053] Figure 7 The fluorescence spectra of the vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 2 and 4, as well as those of MnSe and MoSSe, show that the fluorescence intensity is lower than that of MnSe and MoSSe after the introduction of vacancies, indicating that the photoelectric separation efficiency is improved.

[0054] Figure 8 The electron paramagnetic spectra of the manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 3 and the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst prepared in Example 4 show that the intensity of the catalyst in Example 4 is lower than that in Example 3, which has no vacancies, indicating that it has Mn vacancies.

[0055] Application Example 1

[0056] The heterojunction catalysts prepared in Examples 1-4 were subjected to electrocatalytic hydrogen evolution and photoelectrochemical tests in a three-electrode electrochemical system to evaluate their catalytic performance.

[0057] The photoelectrochemical catalysis test was performed according to the following steps:

[0058] Use 5×5×5 cm 3 A cube-shaped electrolyte was prepared, and a certain concentration of Na₂SO₄ aqueous solution was added as the electrolyte for the photochemical reaction. The photoelectrochemical reaction was performed using an electrochemical workstation with a three-electrode system: a reference electrode, a cathode electrode, and a working electrode. The working electrode was 20 × 10 × 1 mm. 3 Indium tin oxide (ITO) conductive glass coated with catalyst ink.

[0059] 4 mg of the prepared heterojunction catalyst was added to a mixture of 200 μL water, 200 μL ethanol, and 20 μL Nafion solution (5 wt%) to prepare the ink. The mixture was subjected to strong sonication for approximately 30 minutes to form a homogeneous ink solution. Then, 100 μL of the ink was dropped onto a 1 × 1 cm layer of ITO. 2In terms of area, the cathode is a Pt plate relative to the Ag / AgCl electrode. A 300W xenon lamp was placed approximately 20cm from the electrode as the light source. Testing showed that this distance provided good uniformity of light intensity, with similar sunlight intensity. The closer the distance, the significantly higher the electrode temperature. Light intensity was measured using a radiometer. The photocurrent was detected at a scan rate of 10mV / s. The scan rate for linear sweep voltammetry was 10mV / s. In electrochemical impedance spectroscopy (EIS) testing, the voltage was 10mV, and the frequency ranged from 100kHz to 0.1Hz.

[0060] The electrocatalytic test was performed according to the following steps:

[0061] An electrochemical workstation was also used to regulate the hydrogen evolution reaction (HER), employing a three-electrode system consisting of a reference electrode, a cathode electrode, and a working electrode. The working electrode was a glassy carbon electrode (5 mm in diameter) coated with a catalyst. The cathode was a graphite rod, and the reference electrode was an Ag / AgCl electrode.

[0062] A 5×5×5 cm container filled with 0.5M H2SO4 aqueous solution was used. 3 The cubic box serves as the electrochemical reaction site. To prepare the ink, 4 mg of the prepared catalyst was added to a mixture of 200 μL water, 200 μL ethanol, and 20 μL Nafion solution (5 wt%). The mixture was subjected to vigorous sonication for approximately 30 minutes to form an identical ink solution. 10 μL of the ink was dropped onto a glassy carbon electrode, resulting in a catalyst loading of 0.5 ± 0.01 mg / cm³. 2 The electrochemical activity of these products was tested using linear sweep voltammetry (LSV) at a scan rate of 5 mV / s.

[0063] Figure 9 The images show the electrocatalytic hydrogen evolution curves of the manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 1 and 3, the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalysts prepared in Examples 2 and 4, and MnSe and MoSSe. It can be seen that the overpotentials of the products obtained in Examples 1-4 are all lower than those of MnSe and MoSSe, and the introduction of vacancies can further reduce the overpotential. Example 4 has the lowest overpotential.

[0064] Figure 10 The images show the photoelectrochemical hydrogen evolution curves of the manganese selenide-molybdenum selenide-sulfur oxide heterojunction catalysts prepared in Examples 1 and 3, as well as those of MnSe and MoSSe. It can be seen that all the manganese selenide-molybdenum selenide-sulfur oxide heterojunction catalysts exhibit higher photocurrents at 0 V than MnSe and MoSSe, with Example 3 reaching -7.153 mA / cm². 2 .

[0065] Figure 11The unbiased photocurrent plots for the manganese selenide-molybdenum selenide-sulfur heterojunction catalysts prepared in Examples 1 and 3, as well as for MnSe and MoSSe, are shown. All manganese selenide-molybdenum selenide-sulfur heterojunction catalysts exhibit higher photocurrents than MnSe and MoSSe, with Example 3 reaching 10.4 μA / cm. 2 .

Claims

1. A method for preparing a vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst, characterized in that, The preparation method includes the following steps: Step (1): MnCl2 . 4H2O, sodium borohydride, selenium powder, sodium hexadecylbenzenesulfonate, stearyl alcohol and water are mixed in a molar ratio of 1:(2-3):(1-2):(2-3):(1-2):60 and subjected to a hydrothermal reaction. Step (2): The solid-liquid mixture after hydrothermal reaction is centrifuged to separate the solid product, which is then washed with deionized water and alcohol alternately and dried. The dried product is then ground into powder to obtain nano-particle MnSe. Step (3): Mix nano-particles of MnSe, sodium molybdate, Se powder, sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol and water in a molar ratio of 10:(1-3):(1-3):(4-6):(2-4):(1-3):(1-3):(1-3):30:30 to form a precursor solution and carry out a hydrothermal reaction. Step (4): The solid-liquid mixture obtained after the hydrothermal reaction is subjected to solid-liquid centrifugation to separate the solid product. The solid product is washed with deionized water and alcohol alternately and then dried. The dried product is ground into powder to obtain manganese selenide-molybdenum selenide heterojunction catalyst. Step (5): Manganese selenide-molybdenum selenide heterojunction catalyst, ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylenephosphonate, and hexametaphosphate are mixed in a molar ratio of 20:(1-3):(1-3):(2-4):(2-4):(1-3):(1-3) and heated to react; wherein the reaction temperature is 50-80℃ and the reaction time is 1-3 hours; Step (6): The solid-liquid mixture obtained after the reaction is separated by solid-liquid centrifugation. The solid product is taken out, washed alternately with deionized water and alcohol, and then dried. The dried product is ground into powder to obtain the vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst.

2. The preparation method according to claim 1, characterized in that, In step (1), MnCl2 . The molar ratio of 4H2O, sodium borohydride, selenium powder, sodium hexadecylbenzenesulfonate, stearyl alcohol, and water is 1:2:1:2:2:

60.

3. The preparation method according to claim 1, characterized in that, In step (3), the molar ratio of nanoparticles MnSe, sodium molybdate, Se powder, sodium borohydride, hydrazine hydrate, thiourea, thioacetamide, sodium benzoate, ethanol and water is 10:2:2:5:3:2:2:2:30:

30.

4. The preparation method according to claim 1, characterized in that, In step (5), the molar ratio of manganese selenide-molybdenum selenide heterojunction catalyst, ethylenediaminetetraacetic acid, citric acid, iminodiacetic acid, aminotriacetic acid, sodium ethylenediaminetetramethylenephosphonate, and hexametaphosphate is 20:2:2:3:3:2:

2.

5. The preparation method according to claim 1, characterized in that, In step (5), the reaction temperature is 60℃ and the reaction time is 2 hours.

6. The preparation method according to claim 1, characterized in that, In step (1), the hydrothermal reaction temperature is 160-200℃ and the constant temperature time is 16-20 hours; in step (3), the hydrothermal reaction temperature is 160-200℃ and the constant temperature time is 18-24 hours.

7. The preparation method according to claim 1, characterized in that, The drying temperature in steps (2), (4) and (6) is 70-80°C and the drying time is 4-6 hours.

8. A vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst, comprising a MoSSe matrix, MnSe supported on the MoSSe, and vacancies formed on the MnSe, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. The application of the vacancy-controlled manganese selenide-molybdenum selenide heterojunction catalyst of claim 8 as a photoelectrophotocatalyst.

10. The application of the vacancy-regulated manganese selenide-molybdenum selenide heterojunction catalyst of claim 8 as an electrocatalyst.

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