S-doped nitrogen-rich material, and preparation method and application thereof

Abstract

The application belongs to the technical field of preparation of electrocatalytic water hydrogen production catalyst materials, and particularly discloses a S-doped nitrogen-rich material, a preparation method and application thereof, and provides a preparation process of the S-doped nitrogen-rich material, which comprises: taking a two-dimensional transition metal sulfide MS2 as a main template, reacting the main template with a gas containing a guest element N, i.e., NH3, in a high-temperature environment, and gradually replacing the element S in the main template with the guest element N in the reaction process, but not completely replacing the element S, so as to synthesize a N-rich material, i.e., the S-doped N-rich material, which retains the atomic space structure of the main template. The preparation method of the S-doped nitrogen-rich material is simple and controllable, the prepared material belongs to a non-precious metal catalyst, and exhibits excellent electrocatalytic hydrogen evolution performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of electrocatalytic water hydrogen production catalyst materials, and particularly relates to a S-doped nitrogen-rich material and a preparation method and application thereof. BACKGROUND

[0002] Hydrogen energy is a clean, efficient and sustainable green energy. Compared with traditional fossil fuels, hydrogen energy has higher energy density and zero pollution. At present, most of the hydrogen energy is prepared by gray hydrogen production method, which generally uses fossil energy materials. Although the current preparation has high yield, low cost and mature technology, the preparation process will produce greenhouse gases such as carbon dioxide. Green hydrogen technology prepared by electrolysis of water from renewable new energy such as wind energy and photovoltaic will become the development trend of future hydrogen energy. Since the efficiency of hydrogen production by electrolysis of water is relatively low, catalysts play a crucial role in improving the efficiency of electrolysis of water. At present, the electrocatalyst mainly using precious metal Pt has very excellent catalytic efficiency, but due to their low yield and high price, they are not suitable for large-scale application. Transition metal molybdenum has similar electronic structure to Pt, and has attracted widespread attention in the field of electrocatalysis in recent years. Especially the nitrogen-rich (N / metal > 1) two-dimensional sheet-shaped molybdenum nitride material, see the published literature: Jin H, Liu X, Vasileff A, et al. Single-crystal nitrogen-rich two-dimensional Mo5N6 nanosheets for efficient and stable seawater splitting [J]. ACS Nano, 2018, 12 (12): 12761-12769. The published single-crystal nitrogen-rich two-dimensional Mo5N6 nanosheet shows good electrical conductivity and corrosion resistance, and is a very promising transition metal compound. However, due to the high valence state of Mo atoms, the hydrogen adsorption energy is not good, which leads to the unsatisfactory electrocatalytic hydrogen evolution activity of the molybdenum nitride body.

[0003] In the research, it has been proved that hetero-element doping is an effective way to optimize the hydrogen adsorption and desorption performance of the catalyst material by adjusting the electronic structure of the material, so as to improve the catalytic efficiency. Therefore, developing more efficient hetero-element doped nitrogen-rich materials has very important application value in the field of electrocatalytic hydrogen production. SUMMARY

[0004] To address the aforementioned technical problems, this invention provides an sulfur-doped nitrogen-rich material and its preparation method, and also provides the application of the sulfur-doped nitrogen-rich material as a catalyst in electrocatalytic hydrogen evolution. The sulfur-doped nitrogen-rich material provided by this invention uses a two-dimensional transition metal sulfide as the pre-host structure template, with nitrogen (N) as the guest element to incompletely replace the sulfur element in the host structure, achieving a positional interchange between the host and guest elements. This reverse doping method achieves the goal of doping sulfur (S) into the new host nitrogen-rich material structure.

[0005] The technical solution adopted in this invention is as follows:

[0006] This invention discloses a method for preparing S-doped nitrogen-rich materials, such as... Figure 1a As shown, the process includes the following steps: using a two-dimensional transition metal sulfide MS2 as the host template, the host template is reacted with a gas containing the guest element N, namely NH3, in a high-temperature environment. During the reaction, the guest element N gradually replaces the element S in the host template to synthesize a N-rich material that retains the atomic spatial structure of the host template. By controlling the reaction temperature to regulate the degree of substitution reaction, the trace amount of S element in the original host template is not completely replaced by the guest element N, thereby preparing a host structure doped with S element, i.e., a nitrogen-rich material, i.e., an S-doped N-rich material; wherein, M in the two-dimensional transition metal sulfide MS2 is any one of molybdenum (Mo), tungsten (W), or vanadium (V);

[0007] Furthermore, the two-dimensional transition metal sulfide MS2 is a two-dimensional sheet-like MoS2, and using the two-dimensional sheet-like MoS2 as a template, S-doped M5N6 is prepared by topological transformation under an ammonia atmosphere with controlled transformation temperature so that N atoms do not completely replace S atoms in MoS2; preferably, the two-dimensional transition metal sulfide MoS2 is a two-dimensional sheet-like MoS2 prepared on an electrode by hydrothermal synthesis.

[0008] Furthermore, the specific operation of preparing two-dimensional sheet-like MoS2 on the electrode using the hydrothermal synthesis method includes the following steps: The carbon cloth electrode is immersed in nitric acid solution and then washed sequentially with acetone, deionized water, and ethanol; the carbon cloth is then immersed in a DMF solution of (NH4)2MoS4 and stirred to ensure thorough mixing; the DMF solution of (NH4)2MoS4 and the carbon cloth electrode are transferred to a Teflon-lined stainless steel high-pressure reactor for heating and reaction; the high-pressure reactor is cooled to room temperature, the electrode is removed and washed multiple times with deionized water and ethanol, and then dried to obtain the MoS2-loaded carbon cloth electrode.

[0009] Further, the control of the conversion temperature in the ammonia atmosphere makes the N atom incompletely replace the S atom of the MoS2 to obtain the S-doped M5N6, and the specific operation includes the following steps: placing the MoS2-loaded carbon cloth electrode in a tube furnace, heating to perform a topological conversion reaction in an ammonia atmosphere, and the specific heating process is: from room temperature 25 DEG C, at the rate of 10 DEG C per minute -1 to 700 DEG C, and annealing at the temperature for 1h to perform the topological conversion reaction, so as to obtain the S-doped Mo5N6-loaded carbon cloth electrode.

[0010] Preferably, in the operation of placing the carbon cloth electrode in the nitric acid solution for immersion, the concentration of the nitric acid solution used for the immersion of the carbon cloth electrode is 3mol / L -1 , the immersion temperature of the carbon cloth is 80 DEG C, and the immersion time is 12h.

[0011] Preferably, the concentration of the DMF solution of (NH4)2MoS4 is 1mg / ml -1 .

[0012] Preferably, in the operation of stirring the immersion of the carbon cloth in the DMF solution of (NH4)2MoS4, the stirring time is 30-60 minutes to mix uniformly.

[0013] Preferably, the high-pressure reaction kettle is a Teflon-lined stainless steel high-pressure reaction kettle, and the high-pressure reaction temperature in the high-pressure reaction kettle is controlled to be 200 DEG C and the reaction time is 15h.

[0014] Preferably, the drying condition is to dry at a temperature of 70 DEG C for 10h.

[0015] Preferably, the ammonia atmosphere is a mixed gas of ammonia and argon, and the concentration of the ammonia is 5%.

[0016] The application also provides the application of the S-doped nitrogen-rich material prepared above in an electrocatalytic hydrogen evolution reaction, and specifically, the S-doped nitrogen-rich material is used as a catalyst.

[0017] Compared with the prior art, the application has the following advantages:

[0018] The application adopts a topological chemical conversion method, adopts a new path of reverse counter-doping, and prepares an S-doped N-rich material such as Mo5N6 by incomplete N conversion of a two-dimensional transition metal sulfide such as MoS2, greatly reduces the difficulty of material preparation, and the method is simple and controllable.

[0019] Furthermore, the S-doped N-rich materials prepared in this invention, such as the S-doped Mo5N6 prepared for the first time in this invention, use a hydrothermal method to synthesize sheet-like MoS2 as a substrate for topological transformation to prepare S-doped Mo5N6. This ensures that the obtained S-doped Mo5N6 also has a layered structure, a large specific surface area, more exposed catalytic active sites, and higher activity. The doping of S element changes the electronic structure of Mo5N6, greatly reducing the Gibbs free energy of the catalytic reaction, making the material exhibit excellent catalytic activity similar to that of metallic Pt, and having better electrocatalytic hydrogen evolution performance than most molybdenum nitride materials. Attached Figure Description

[0020] Figure 1a This is a schematic diagram illustrating the principle of preparing S-doped nitrogen-rich materials using topological transformation according to the present invention.

[0021] Figure 1b This is a schematic diagram illustrating the principle of preparing S-doped Mo5N6 using topological transformation according to the present invention.

[0022] Figure 2a The image shows the microstructure of MoS2 under a scanning electron microscope in Example 1.

[0023] Figure 2b The image shows the microstructure of S-doped Mo5N6 under a scanning electron microscope in Example 1.

[0024] Figure 3 The images show the product characterization images of MoS2 at different topological transformation temperatures in Example 1, where a is the XRD pattern, b is the Raman pattern, and c, d and e are XPS patterns.

[0025] Figure 4a Polarization curves for different materials;

[0026] Figure 4b For different materials, the Tafel slopes are given.

[0027] Figure 5 The electrocatalytic performance of the S-doped Mo5N6 prepared in this invention is compared with the catalytic performance of other molybdenum nitride materials reported in the literature. Detailed Implementation

[0028] The application is further described below in combination with specific examples and drawings. The following examples take the preparation of S-doped Mo5N6 material as an example to specifically describe the preparation process of the S-doped nitrogen-rich material of the application, and the S-doped Mo5N6 material is used in electrocatalytic hydrogen evolution. The preparation process mainly includes two steps. One is to prepare MoS2 nanosheets on an electrode by using a hydrothermal synthesis method. The other is to perform an ammoniation reaction on the MoS2 nanosheets by using a topological chemical conversion method, to achieve incomplete substitution of N element for S element by controlling the temperature, and to obtain S-doped Mo5N6 nanosheets. The conversion process is shown in Figure 1b ;

[0029] Main raw material sources: ammonium tetrathiomolybdate (NH4) 2Mo2S4 is purchased from Sigma-Aldrich Company; carbon cloth is purchased from Canrd New Energy Technology Company, model W1S1009; DMF is purchased from AlfaAesar Company.

[0030] Main reaction equipment and devices involved: a stainless steel reaction kettle with a polytetrafluoroethylene lining is purchased from Shanghai Licen Science and Technology Company, model LC-KH-50; a forced air drying oven is purchased from Shanghai Licen Science and Technology Company, model LC-101-1B; a tubular furnace used for preparation is produced by Hefei Kexing Material Technology Co., Ltd., model OTF-1200X.

[0031] Other materials, main reagents and equipment involved in the test process: an electrochemical workstation used in the electrochemical test process is produced by Shanghai Chenhua Instrument Co., Ltd., model CHI 760E; a 20% Pt / C electrode is purchased from Sigma-Aldrich.

[0032] Example 1: S-doped Mo5N6 carbon cloth electrode

[0033] Step S1: cut the carbon cloth into 3cm×4cm in size, and sequentially ultrasonic clean it in acetone, anhydrous ethanol and deionized water. Dissolve 30mg of ammonium tetrathiomolybdate (NH4) 2Mo2S4 in 30ml of N,N-dimethylformamide DMF, and after complete dissolution, place the cleaned carbon cloth in the prepared solution, and stir for 30min. Pour the carbon cloth and the solution into a stainless steel reaction kettle with a polytetrafluoroethylene lining, seal the reaction kettle, and place it in a forced air drying oven, and heat to 200℃, and react for 15h. After the reaction is completed, naturally cool the reaction kettle to room temperature, take out the sample, sequentially rinse it with deionized water and ethanol for 3 times, and then place it in a drying oven, and dry it at 70℃ for 10h, to obtain a carbon cloth electrode loaded with MoS2 nanosheets. The morphology of the MoS2 nanosheets is shown in Figure 2a .

[0034] Step S2, the obtained carbon cloth electrode loaded with MoS2 nanosheets was placed in a tube furnace, and a mixed gas of ammonia and argon was introduced, with the ammonia concentration controlled at about 5%, and the temperature was raised at a rate of 10°C / min from room temperature 25°C to 700°C, and then annealed at the temperature for 1 h to perform a topological chemical conversion reaction, thereby obtaining a carbon cloth electrode loaded with S-doped Mo5N6, and the morphology of S-doped Mo5N6 is shown in FIG. 2b. -1 Step S2, the obtained carbon cloth electrode loaded with MoS2 nanosheets was placed in a tube furnace, and a mixed gas of ammonia and argon was introduced, with the ammonia concentration controlled at about 5%, and the temperature was raised at a rate of 10°C / min from room temperature 25°C to 700°C, and then annealed at the temperature for 1 h to perform a topological chemical conversion reaction, thereby obtaining a carbon cloth electrode loaded with S-doped Mo5N6, and the morphology of S-doped Mo5N6 is shown in FIG. 2b. Figure 2b

[0035] Comparative Example 1: Carbon cloth electrode loaded with Mo5N6

[0036] Comparative Example 1 and Example 1 differ only in Step S2. Specifically, Step S2 of Comparative Example 1 is as follows: the obtained carbon cloth electrode loaded with MoS2 nanosheets was placed in a tube furnace, and a mixed gas of ammonia and argon was introduced, with the ammonia concentration controlled at about 5%, and the temperature was raised at a rate of 10°C / min from room temperature 25°C to 800°C, and then annealed at the temperature for 1 h to perform a topological chemical conversion reaction, thereby obtaining a carbon cloth electrode loaded with Mo5N6. -1 Comparative Example 1 and Example 1 differ only in Step S2. Specifically, Step S2 of Comparative Example 1 is as follows: the obtained carbon cloth electrode loaded with MoS2 nanosheets was placed in a tube furnace, and a mixed gas of ammonia and argon was introduced, with the ammonia concentration controlled at about 5%, and the temperature was raised at a rate of 10°C / min from room temperature 25°C to 800°C, and then annealed at the temperature for 1 h to perform a topological chemical conversion reaction, thereby obtaining a carbon cloth electrode loaded with Mo5N6.

[0037] Comparative Example 2: Carbon cloth electrode loaded with MoS2-Mo5N6

[0038] Comparative Example 2 and Example 1 differ only in Step S2. Specifically, Step S2 of Comparative Example 1 is as follows: the obtained carbon cloth electrode loaded with MoS2 nanosheets was placed in a tube furnace, and a mixed gas of ammonia and argon was introduced, with the ammonia concentration controlled at about 5%, and the temperature was raised at a rate of 10°C / min from room temperature 25°C to 800°C, and then annealed at the temperature for 1 h to perform a topological chemical conversion reaction, thereby obtaining a carbon cloth electrode loaded with Mo5N6. -1 Comparative Example 2 and Example 1 differ only in Step S2. Specifically, Step S2 of Comparative Example 1 is as follows: the obtained carbon cloth electrode loaded with MoS2 nanosheets was placed in a tube furnace, and a mixed gas of ammonia and argon was introduced, with the ammonia concentration controlled at about 5%, and the temperature was raised at a rate of 10°C / min from room temperature 25°C to 800°C, and then annealed at the temperature for 1 h to perform a topological chemical conversion reaction, thereby obtaining a carbon cloth electrode loaded with Mo5N6.

[0039] Comparative Example 3: Carbon cloth electrode loaded with N-doped MoS2

[0040] Comparative Example 3 and Example 1 differ only in Step S2. Specifically, Step S2 of Comparative Example 1 is as follows: the obtained carbon cloth electrode loaded with MoS2 nanosheets was placed in a tube furnace, and a mixed gas of ammonia and argon was introduced, with the ammonia concentration controlled at about 5%, and the temperature was raised at a rate of 10°C / min from room temperature 25°C to 800°C, and then annealed at the temperature for 1 h to perform a topological chemical conversion reaction, thereby obtaining a carbon cloth electrode loaded with Mo5N6. -1 Comparative Example 3 and Example 1 differ only in Step S2. Specifically, Step S2 of Comparative Example 1 is as follows: the obtained carbon cloth electrode loaded with MoS2 nanosheets was placed in a tube furnace, and a mixed gas of ammonia and argon was introduced, with the ammonia concentration controlled at about 5%, and the temperature was raised at a rate of 10°C / min from room temperature 25°C to 800°C, and then annealed at the temperature for 1 h to perform a topological chemical conversion reaction, thereby obtaining a carbon cloth electrode loaded with Mo5N6.

[0041] Comparative Example 4: Carbon cloth electrode loaded with MoS2 nanosheets

[0042] Comparative Example 4 and Example 1 differ only in that Comparative Example 4 only includes Step S1, i.e., the preparation of a carbon cloth electrode loaded with MoS2 nanosheets.

[0043] Comparative Example 5: 20% Pt / C electrode ​

[0044] Cut the carbon cloth into 3cm x 4cm size, and sequentially ultrasonic cleaning in acetone, anhydrous ethanol, deionized water. Purchase commercial 20% Pt / C electrode, and coat on the cleaned carbon cloth to obtain the Pt / C loaded carbon cloth electrode.

[0045] Product characterization

[0046] In examples 1, comparative examples 1 to 3, different conversion products were obtained by setting different temperatures for topological chemical conversion reaction. The structure characterization of the conversion products under different temperature conditions is shown in Table 1. Figure 3 , wherein a is the XRD spectrum, b is the Raman spectrum, c, d and e are XPS spectra; and the topological chemical conversion reaction under the condition of 700℃ corresponding to example 1 can only obtain the S-doped Mo5N6 loaded carbon cloth electrode as described in the present application.

[0047] Test example 1: electrocatalytic performance test

[0048] The electrocatalytic performance of the samples prepared in example 1, comparative example 4 and comparative example 5 was tested by electrolytic water hydrogen evolution catalytic reaction.

[0049] The samples prepared in example 1, i.e. the S-doped Mo5N6 loaded carbon cloth electrode, the electrode sample prepared in comparative example 1, i.e. the Mo5N6 loaded carbon cloth electrode, the sample prepared in comparative example 4, i.e. the MoS2 nanosheet loaded carbon cloth electrode, and the commercial 20% Pt / C electrode sample prepared in comparative example 5 were respectively subjected to electrocatalytic performance test. Each sample was tested with 0.5M H2SO4 as electrolyte, Ag / AgCl electrode as reference electrode, and carbon rod as counter electrode. All electrochemical characterization was carried out in a three-electrode system on a CHI 760E electrochemical workstation. The 0.5M H2SO4 electrolyte solution was purged with Ar gas for 1 hour. All potentials here are with iR compensation and are calibrated against the reversible hydrogen electrode (RHE). The calibration was carried out in high-purity hydrogen-saturated electrolyte with a platinum wire as the working electrode and a scan rate of 1mV·s -1 . The average value of the two potentials of each CV curve crossing zero current was taken as the thermodynamic potential. In 0.5M H2SO4 solution, E(RHE) = E(silver / silver chloride solution) + 0.213V for saturated silver / silver chloride electrode. The polarization curve LSV scan speed was set to 2mV·s -1 .

[0050] The test results are as follows:

[0051] As shown in Figure 4, the final sample prepared in example 1, i.e. the S-doped Mo5N6 loaded carbon cloth electrode, obtained a current density of 10mA·cm -2overpotential of 56 mV and a Tafel slope of 37.9 mV dec -1 ; the electrode sample in Comparative Example 1, i.e. Mo5N6-carbon cloth electrode, gave a current density of 10 mA cm -2 overpotential of 131 mV and a Tafel slope of 76.1 mV dec -1 ; the electrode sample in Comparative Example 4, i.e. MoS2nanosheets-carbon cloth electrode, gave a current density of 10 mA cm -2 overpotential of 274 mv and a Tafel slope of 101.8 mV dec -1 ; the electrode sample in Comparative Example 5, i.e. 20% Pt / C electrode, gave a current density of 10 mA cm -2 overpotential of 40 mv and a Tafel slope of 29.7 mV dec -1 .

[0052] As shown in Table 1, the final sample prepared in Example 1, i.e. S-doped Mo5N6-carbon cloth electrode, gave an overpotential and a Tafel slope of 56 mV and 37.9 mV dec, respectively; the electrode sample in Comparative Example 1, i.e. Mo5N6-carbon cloth electrode, gave a current density of 10 mA cm -2 at an overpotential of 56 mV and a Tafel slope of 37.9 mV dec. Figure 5 Figure 4a As shown in Table 1, the final sample prepared in Example 1, i.e. S-doped Mo5N6-carbon cloth electrode, gave an overpotential and a Tafel slope of 56 mV and 37.9 mV dec, respectively; the electrode sample in Comparative Example 1, i.e. Mo5N6-carbon cloth electrode, gave a current density of 10 mA cm -2 at an overpotential of 56 mV and a Tafel slope of 37.9 mV dec. Figure 4b Figure 5 As shown in Table 1, the final sample prepared in Example 1, i.e. S-doped Mo5N6-carbon cloth electrode, gave an overpotential and a Tafel slope of 56 mV and 37.9 mV dec, respectively; the electrode sample in Comparative Example 1, i.e. Mo5N6-carbon cloth electrode, gave a current density of 10 mA cm -2 at an overpotential of 56 mV and a Tafel slope of 37.9 mV dec. Figure 5 The catalytic performance data of other reported molybdenum nitride-based materials mentioned in the literature are derived from the following literature:

[0053] H. Jin, Q. Gu, B. Chen, et al. Molten salt-directed catalytic synthesis of 2D layered transition-metal nitrides for efficient hydrogen evolution [J], Chem, 6 (2020) 2382-2394;

[0054] C. Pi, X. Li, X. Zhang, et al. In-plane Mott-Schottky effects enabling efficient hydrogen evolution from Mo5N6-MoS2 heterojunction nanosheets in universal-pH electrolytes [J], Small, 18 (2022) 2201137;

[0055] Q. Wang, Y. Zhang, W. Ni, et al. Free-standing phosphorous-doped molybdenum nitride in 3D carbon nanosheet towards hydrogen evolution at all pH values [J], J. Energy Chem., 50 (2020) 44-51;

[0056] J. Xiong, W. Cai, W. Shi, et al. Salt-templated synthesis of defect-rich MoN nanosheets for boosted hydrogen evolution reaction [J], J. Mater. Chem. A, 5 (2017) 24193-24198;

[0057] N. Yao, R. Meng, J. Su, et al. Dual-phase engineering of MoN / Co4N with tailored electronic structure for enhanced hydrogen evolution [J], Chem. Eng. J., 421 (2021) 127757;

[0058] A. Wu, Y. Gu, Y. Xie, et al., Interfacial engineering of MoS2 / MoN heterostructures as efficient electrocatalyst for pH-universal hydrogen evolution reaction [J], J. Alloy. Compd., 867 (2021) 159066;

[0059] Y. Zhu, G. Chen, X. Xu, et al. Enhancing electrocatalytic activity for hydrogen evolution by strongly coupled molybdenum nitride@nitrogen-doped carbon porous nano-octahedrons [J], ACS Catal., 7 (2017) 3540-3547;

[0060] S. Li, C. Cheng, A. Sagaltchik, et al. Metal-organic precursor-derived mesoporous carbon spheres with homogeneously distributed molybdenum carbide / nitride nanoparticles for efficient hydrogen evolution in alkaline media [J], Adv. Funct. Mater., 29 (2019) 1807419;

[0061] X. Zhang, F. Zhou, W. Pan, et al. General construction of molybdenum-based nanowire arrays for PH-universal hydrogen evolution electrocatalysis [J], Adv. Funct. Mater., 28 (2018) 1804600;

[0062] Y. Zhao, K. Kamiya, K. Hashimoto, et al. In situ CO2-emission assisted synthesis of molybdenum carbonitride nanomaterial as hydrogen evolution electrocatalyst [J], J. Am. Chem. Soc., 137 (2015) 110-113;

[0063] J. Miao, Z. Lang, X. Zhang, et al. Polyoxometalate-derived hexagonal molybdenum nitrides (MXenes) supported by boron, nitrogen codoped carbon nanotubes for efficient electrochemical hydrogen evolution from seawater [J], Adv. Funct. Mater., 29 (2019) 1805893;

[0064] Y. Ma, S. Lu, G. Han, et al. Chemical vapor deposition of two-dimensional molybdenum nitride / graphene van der Waals heterostructure with enhanced electrocatalytic hydrogen evolution performance [J], Appl. Surf. Sci., 589 (2022) 152934;

[0065] Q. Wu, D. Zhao, X. Yu, et al. Vapor-assisted engineering heterostructure of 1D Mo3N2 nanorod decorated with nitrogen-doped carbon for rapid pH-Universal hydrogen evolution reaction [J], In. J. Hydrog. Energy, 47 (2022) 5064-5073;

[0066] Y. Gu, A. Wu, Y. Jiao, et al. Two-dimensional porous molybdenum phosphide / nitride heterojunction nanosheets for pH-universal hydrogen evolution reaction [J], Angew. Chem. Int. Ed., 60 (2021) 6673-6681;

[0067] H. Jin, H. Yu, H. Li, et al. MXene analogue: a 2D nitridene solid solution for high-rate hydrogen production [J], Angew. Chem. Int. Ed., (2022) e202203850.

[0068] The above examples are only examples for illustrating the technical solutions of the application, and do not represent the protection scope of the application. The protection scope of the application is subject to the description of the claims.

Claims

1. A method for preparing an S-doped nitrogen-rich material, characterized in that, Includes the following steps: Using two-dimensional transition metal sulfide MS2 as the host template, the host template is reacted with a gas containing guest element N, namely NH3, in a high-temperature environment. During the reaction, the guest element N gradually replaces element S in the host template but does not completely replace it, in order to synthesize an N-rich material that retains the atomic spatial structure of the host template, namely an S-doped N-rich material; wherein, M in the two-dimensional transition metal sulfide MS2 is any one of molybdenum Mo, tungsten W, or vanadium V. The two-dimensional transition metal sulfide MS2 is a two-dimensional sheet-like MoS2. Using the two-dimensional sheet-like MoS2 as a template, S-doped M5N6 is prepared by topological transformation under an ammonia atmosphere with controlled transformation temperature so that N atoms do not completely replace S atoms in MoS2.

2. The method as described in claim 1, characterized in that, The two-dimensional transition metal sulfide MoS2 is a two-dimensional sheet-like MoS2 prepared on an electrode using a hydrothermal synthesis method.

3. The method as described in claim 2, characterized in that, The specific operation of preparing two-dimensional sheet-like MoS2 on the electrode using the hydrothermal synthesis method includes the following steps: The carbon cloth electrode is immersed in nitric acid solution and then washed sequentially with acetone, deionized water, and ethanol; the carbon cloth is then immersed in a DMF solution of (NH4)2MoS4 and stirred until fully mixed; the (NH4)2MoS4 DMF solution and the carbon cloth electrode are transferred to a Teflon-lined stainless steel high-pressure reactor for heating and reaction; the high-pressure reactor is cooled to room temperature, the electrode is removed and washed multiple times with deionized water and ethanol, and then dried to obtain the MoS2-loaded carbon cloth electrode.

4. The method as described in claim 1, characterized in that, The preparation of S-doped M5N6 by controlling the conversion temperature under an ammonia atmosphere to prevent complete replacement of S atoms by N atoms in MoS2 includes the following steps: placing a MoS2-loaded carbon cloth electrode in a tube furnace and heating it under an ammonia atmosphere to carry out a topological transformation reaction. Specifically, the heating process starts from room temperature (25°C) and proceeds at 10°C / min increments. -1 The temperature was raised to 700℃ and annealed at that temperature for 1 hour to carry out a topological transformation reaction, resulting in a carbon cloth electrode loaded with S-doped Mo5N6.

5. The method as described in claim 3, characterized in that, In the step of immersing the carbon cloth electrode in a nitric acid solution, the concentration of the nitric acid solution used for immersion is 3 mol·L⁻¹. -1 The carbon cloth was soaked at 80℃ for 12 hours.

6. The method as described in claim 3, characterized in that, The concentration of the (NH4)2MoS4 DMF solution was 1 mg·ml. -1 .

7. The method as described in claim 1, characterized in that, The ammonia atmosphere is a mixture of ammonia and argon, wherein the concentration of ammonia is 5%.

8. The S-doped nitrogen-rich material prepared by the method according to any one of claims 1-7.

9. The application of the S-doped nitrogen-rich material prepared by the method according to any one of claims 1-7 as a catalyst for the electrocatalytic hydrogen evolution reaction.

Images