Preparation and NRR application of a defect-rich core-shell heterojunction catalyst

Abstract

The present invention selects antimony, which is inert to hydrogen ion adsorption, and molybdenum, which has good nitrogen reduction activity, and simultaneously applies the two strategies of vacancy engineering and interface engineering to prepare the P-Sb2S3 / MoS2 core-shell heterojunction by a continuous hydrothermal method (Figure 1 of the specification). The formation of the heterojunction promotes the construction of the built-in electric field and accelerates the flow of electrons, thereby improving the electronic activity of the material. P doping induces the formation of abundant sulfur vacancies, which significantly promotes the adsorption of nitrogen by the material. The above structure enables the material to exhibit excellent electrocatalytic nitrogen reduction (NRR) performance, and the ammonia production rate reaches 40.95μg·h ‑1 The Faradaic efficiency reached 15.79%, demonstrating an excellent balance between ammonia production rate and Faradaic efficiency. Furthermore, P‑Sb2S3 / MoS2 exhibited excellent stability and ammonia production selectivity.

Description

Technical Field

[0001] The present invention relates to the fields of new materials technology and electrocatalysis. Specifically, it relates to a phosphorus-doped bimetallic sulfide core-shell heterojunction electrocatalytic material and a synthesis method thereof. The synthesized phosphorus-doped antimony sulfide / molybdenum sulfide heterojunction electrocatalyst (P-Sb2S3 / MoS2) has a novel structure and excellent electrochemical performance. Background Art

[0002] Ammonia (NH3) is one of the most important chemicals in industrial and agricultural production and plays a vital role in the economic development of human society. Ammonia can be used not only in the synthesis of fertilizers but also as a refrigerant. At the same time, due to its inherent hydrogen content of 17.6wt%, its energy density is as high as 4.3kW·h. -1 Ammonia is therefore one of the most promising energy carriers. Currently, large-scale industrial ammonia production relies primarily on the Haber-Bosch process. Using an iron-based catalyst, N≡N is cracked at extremely high temperatures, while nitrogen is reduced to ammonia under immense pressure. This process typically consumes vast quantities of fossil energy, generating over 300 million metric tons of CO₂ annually, causing significant pollution. In the pursuit of sustainable development, ammonia production urgently needs to be transformed towards cleaner methods, leading to the emergence of electrocatalytic nitrogen fixation. However, due to the low solubility of nitrogen in water, nitrogen adsorption and activation are difficult, and coupled with the significant competitive hydrogen evolution reaction, the activity and selectivity of electrocatalytic nitrogen reduction are severely limited. Simultaneously improving the ammonia production rate and Faradaic efficiency of electrocatalytic nitrogen reduction, while achieving a balance between electrocatalyst activity and selectivity, remains a significant challenge in the field of electrocatalytic nitrogen reduction.

[0003] In nature, microorganisms convert atmospheric nitrogen into ammonia under the action of nitrogenase. Mo, as an important component of biological nitrogenase, plays an indispensable role by virtue of its unique electronic structure and synergistically with other metals. Inspired by the active sites of Mo, Mo-based catalysts have made rapid progress in the field of electrocatalytic nitrogen fixation. Studies have shown that the unoccupied d orbitals of Mo can accept electrons from nitrogen, and the occupied d orbitals feed back electrons to the π* orbitals of nitrogen. This electron feedback mechanism can effectively promote the adsorption and activation of nitrogen, so Mo-based catalysts often achieve good NRR activity. However, it is limited by the fact that Mo-based catalysts react with H +Stronger adsorption and the accompanying hydrogen evolution reaction make its electrocatalytic nitrogen reduction (NRR) selectivity significantly lower. For example, HYZhou et al. (Applied Catalysis B: Environmental, 2023, 339: 123133) prepared a Ni3Mo alloy. The Mo active sites effectively promoted the adsorption and activation of nitrogen, and its ammonia production rate reached 17.35±0.3μg·h -1 cm -2 However, since Ni and Mo are both transition metal elements, the electrocatalytic system is severely affected by the hydrogen evolution reaction, and its Faradaic efficiency is only 8.94±0.2%. Zhifeng He et al. (ACS Appl. NanoMater. 2022, 5, 4, 5470–5478) prepared iron-doped 1T / 2H-MoS2 / C nanoflowers rich in sulfur vacancies through pectin-assisted hydrothermal reaction, and the highest Faradaic efficiency was only 9.2% at -0.3V (vs RHE). Unlike Mo, studies have shown that the NRR activity of Sb is generally low. For example, Shihai Cao et al. (ACS Appl. Nano Mater. 2022, 5, 3, 3591–3598) prepared S-doped Sb2O3 nanorods by self-assembly and calcination methods. Due to the poor NRR activity of Sb, the ammonia production rate was only 6.88 μg·h -1 cm -2 In another report by Shihai Cao et al. (ACS Appl. Mater. Interfaces 2021, 13, 34, 40618–40628), the ammonia production rate of the few-layer antimonene they prepared was only 2.08 μg·h -1 cm -2 However, since the adsorption capacity for protons in water is lower than that for nitrogen, Sb-based catalysts are significantly less affected by the hydrogen evolution reaction. Therefore, the introduction of Sb elements is expected to improve the Faradaic efficiency of NRR catalysts.

[0004] Applying heterojunction engineering to the design of efficient NRR catalysts is an effective strategy. Due to the lattice mismatch at the interface between different components, heterojunction structures involving disorder, defects and multiphases can expose more catalytic active sites. Secondly, strong interfacial interactions also help to establish more charge and mass transfer channels, induce better electronic coupling effects and regulate the free energy of intermediates, thereby further optimizing the adsorption and desorption of NRR intermediates and promoting the improvement of NRR performance. In addition, the creation of anion vacancies by heteroatom doping has been proven to be effective. On the one hand, abundant vacancy defects can expose more active sites in the catalyst. On the other hand, the creation of anion vacancies by heteroatom doping can effectively regulate the electronic structure of the catalyst, thereby improving the NRR performance of the catalyst. Summary of the Invention

[0005] In view of the shortcomings and deficiencies in the above-mentioned prior art, the present invention provides a high-performance phosphorus-doped bimetallic sulfide heterojunction electrocatalytic material. Lamellar MoS2 grows uniformly on the surface of Sb2S3 and is well dispersed, which significantly increases the surface area of ​​the material, is beneficial for the catalyst to expose more active sites, and at the same time strengthens the contact between the catalyst and the electrolyte. The formation of the heterostructure not only produces abundant interface defects, but also enhances the electronic activity of the catalyst, promotes the flow and transfer of electrons, is beneficial to optimize NRR intermediates, and reduces the NRR reaction energy barrier. In addition, phosphorus doping induces the generation of abundant sulfur vacancies, which is beneficial to enhance the catalyst's adsorption capacity for nitrogen. The preparation method of the heterogeneous electrocatalytic material is simple and efficient, the raw material source is abundant and the cost is low, and the prepared electrocatalytic material exhibits good electrochemical performance as an electrochemical nitrogen fixation catalyst.

[0006] The present invention also provides a method for preparing the above-mentioned high-performance phosphorus-doped antimony sulfide / molybdenum sulfide heterojunction electrocatalyst (P-Sb2S3 / MoS2), as well as its application in electrocatalytic nitrogen fixation.

[0007] The preparation of the above-mentioned high-performance P-Sb2S3 / MoS2 heterojunction electrocatalytic material includes the following steps:

[0008] (1) A certain amount of antimony source and sulfur source were dispersed in 50 mL of water. After being stirred for 30 min, the mixture was transferred to a 100 mL polytetrafluoroethylene reactor. After reacting at a suitable temperature for a period of time, the obtained product was washed thoroughly with water and anhydrous ethanol, and then dried at 60 ° C for 10 h to obtain product 1.

[0009] (2) The molybdenum source and product 1 were dispersed in 60 mL of water in a certain proportion, and appropriate amounts of sulfur source and phosphorus source were added. After sufficient stirring, the mixture was transferred to a 100 mL polytetrafluoroethylene reactor and fully reacted at a certain temperature. The reaction product was fully washed with water and anhydrous ethanol and dried at 60 ° C for 10 h to obtain a high-performance P-Sb2S3 / MoS2 heterojunction electrocatalytic material.

[0010] According to the present invention, preferably, the product 1 in step (1) is Sb2S3.

[0011] According to the present invention, preferably, the antimony source in step (1) is antimony trichloride, and the sulfur source is thiourea.

[0012] According to the present invention, preferably, the molybdenum source in step (2) is ammonium molybdate tetrahydrate, the sulfur source is thiourea, and the phosphorus source is sodium dihydrogen phosphate.

[0013] According to the present invention, preferably, the molar ratio of the antimony source to the sulfur source in step (1) is controlled at 1:(2-4), most preferably 1:3.

[0014] According to the present invention, preferably, the reaction temperature of the hydrothermal reaction in step (1) is 150-180°C, most preferably 160°C.

[0015] According to the present invention, preferably, the hydrothermal reaction time in step (1) is 15-30 hours, most preferably 24 hours.

[0016] According to the present invention, preferably, the molar ratio of antimony element to molybdenum element in step (2) is controlled to be (1-3):1, most preferably 2:1.

[0017] According to the present invention, preferably, the molar ratio of the phosphorus source to the sulfur source in step (2) is (0.5-2):10, most preferably 1:10.

[0018] According to the present invention, preferably, the reaction temperature of the hydrothermal reaction in step (2) is 180-220°C, most preferably 200°C.

[0019] According to the present invention, preferably, the hydrothermal time in step (2) is controlled to be 10-24 hours, and the optimal time is 16 hours.

[0020] The present invention also provides the application of the above-mentioned high-performance P-Sb2S3 / MoS2 heterojunction material in electrocatalytic nitrogen fixation.

[0021] The electrochemical workstation was equipped with a standard three-electrode system to test the electrocatalytic reduction of nitrogen to ammonia using P-Sb2S3 / MoS2. The specific test results are as follows:

[0022] The polarization curves (LSV), cyclic voltammetry (CV) and chronoamperometry (CA) were obtained using a CHI 760E electrochemical workstation in 0.1 M Na2SO4 solution. The reference electrode was a saturated silver chloride electrode, the counter electrode was a graphite rod electrode, and the working electrode was a carbon paper loaded with a catalyst. The catalyst loading was 0.3 mg / cm -2 Before each experiment, the electrolyte was pre-filled with high-purity argon for 30 min to remove air and eliminate interference, and the LSV scan rate was set to 5 mV / s.

[0023] Electrochemical impedance spectroscopy (EIS) was performed using a CHI 760E electrochemical workstation. Other test conditions were kept the same, and the frequency was set from 1000000 Hz to 0.01 Hz.

[0024] All potential values ​​in the experiment were calibrated by a standard hydrogen electrode. The electrode potential calibration equation is:

[0025]

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The present invention prepares a high-performance P-Sb2S3 / MoS2 heterojunction electrocatalytic material with readily available and inexpensive raw materials and simple preparation conditions. The material is characterized by thin layered MoS2 uniformly grown on the surface of rod-shaped Sb2S3, and under the doping of P, a heterostructure is formed. The stretched lamellar MoS2 significantly increases the specific surface area of ​​the catalyst, which is conducive to exposing more active sites. At the same time, the formation of the heterojunction promotes the construction of the material's built-in electric field, accelerates the flow and transfer of electrons, and enhances the electronic activity of the material, which is conducive to optimizing NRR reaction intermediates and improving NRR performance. In addition, the doping of P induces abundant sulfur vacancies, and the large number of interface defects generated by the formation of the heterojunction help to enhance the catalyst's adsorption capacity for nitrogen, thereby improving the NRR performance of P-Sb2S3 / MoS2.

[0028] 2. The present invention has found through chronoamperometric test and UV spectrophotometry that the P-Sb2S3 / MoS2 heterojunction shows good NRR performance in the range of -0.45 to -0.65V (vs.RHE). When the potential is -0.55V (vs.RHE), the ammonia production rate reaches The Faradaic efficiency was 15.79%, significantly exceeding that of Sb2S3 / MoS2 heterojunctions, MoS2, and Sb2S3. Furthermore, after multiple cycles of electrolysis, the ammonia production rate and Faradaic efficiency of P-Sb2S3 / MoS2 fluctuated only slightly, and no hydrazine byproduct was detected in the electrolyte, demonstrating excellent stability and selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a TEM image of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3.

[0030] Figure 2 This is an SEM image of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3.

[0031] Figure 3 This is the XRD pattern of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3.

[0032] Figure 4 This is the HRTEM image of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3.

[0033] Figure 5 This is the EPR graph of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3.

[0034] Figure 6 This is the Raman graph of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3.

[0035] Figure 7 This is the XPS graph of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3.

[0036] Figure 8 This is a diagram of the ammonia production rate and Faraday efficiency of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material at different potentials in experimental example 2.

[0037] Figure 9 This is a graph of ammonia production rate and Faraday efficiency of six consecutive tests of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material in Experimental Example 2.

[0038] Figure 10 This is the ultraviolet spectrum of the detection of hydrazine, a by-product of the catalytic electrocatalytic material of P-Sb2S3 / MoS2 heterojunction in Experimental Example 2.

[0039] Figure 11 The C of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material of Experimental Example 2 dl Comparison picture.

[0040] Figure 12 This is the EIS comparison diagram of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material of experimental example 2. DETAILED DESCRIPTION

[0041] The following is a detailed description of the method for preparing high-performance P-Sb2S3 / MoS2 heterojunction electrocatalytic materials according to the present invention in combination with specific implementation methods and examples.

[0042] The raw materials used in the examples are all conventional commercial products. The main experimental reagents used are listed below:

[0043] Antimony trichloride (SbCl3, AR), ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 4H2O,AR), sodium dihydrogen phosphate (NaH2PO4,AR), thiourea (CH4N2S,AR).

[0044] The present invention is described below by way of example, and the present invention includes but is not limited to the following embodiments:

[0045] Example 1. Preparation of high-performance P-Sb2S3 / MoS2 heterojunction electrocatalytic materials

[0046] 0.684g SbCl3 and 0.457g CH4N2S were dissolved in 50mL water, stirred thoroughly for 30min, and then transferred to a 100mL polytetrafluoroethylene reactor and reacted at 180℃ for 18 hours. The reaction product was washed thoroughly with water and anhydrous ethanol, and dried at 60℃ for 10h to obtain Sb2S3 crystals. 0.639g CH4N2S, 0.494g (NH4)6Mo7O 24 4H2O and 0.101g NaH2PO4 were dispersed in 60mL of water, and 0.477g of the previously prepared Sb2S3 crystals were added. After thorough stirring for 30 minutes, the mixture was transferred to a 100mL polytetrafluoroethylene reactor and reacted at 180°C for 24 hours. The reaction product was thoroughly washed with water and anhydrous ethanol and dried at 60°C for 10 hours to obtain the P-Sb2S3 / MoS2 composite material.

[0047] Example 2: Preparation of high-performance P-Sb2S3 / MoS2 heterojunction electrocatalytic materials

[0048] 0.684g SbCl3 and 1.142g CH4N2S were dissolved in 50mL water, stirred thoroughly for 30min, and then transferred to a 100mL polytetrafluoroethylene reactor and reacted at 160℃ for 18 hours. The reaction product was washed thoroughly with water and anhydrous ethanol, and dried at 60℃ for 10h to obtain Sb2S3 crystals. 0.639g CH4N2S, 0.247g (NH4)6Mo7O 244H2O and 0.051g NaH2PO4 were dispersed in 60mL of water, and 0.477g of the previously prepared Sb2S3 crystals were added. After thorough stirring for 30 minutes, the mixture was transferred to a 100mL polytetrafluoroethylene reactor and reacted at 200°C for 24 hours. The reaction product was thoroughly washed with water and anhydrous ethanol and dried at 60°C for 10 hours to obtain the P-Sb2S3 / MoS2 composite material.

[0049] Example 3. Preparation of high-performance P-Sb2S3 / MoS2 heterojunction electrocatalytic materials

[0050] 0.684g SbCl3 and 0.685g CH4N2S were dissolved in 50mL water, stirred thoroughly for 30min, and then transferred to a 100mL polytetrafluoroethylene reactor and reacted at 160℃ for 24h. The reaction product was washed thoroughly with water and anhydrous ethanol, and dried at 60℃ for 10h to obtain Sb2S3 crystals. 0.639g CH4N2S, 0.247g (NH4)6Mo7O 24 4H2O and 0.101g NaH2PO4 were dispersed in 60mL of water, and 0.477g of the previously prepared Sb2S3 crystals were added. After thorough stirring for 30 minutes, the mixture was transferred to a 100mL polytetrafluoroethylene reactor and reacted at 200°C for 16 hours. The reaction product was thoroughly washed with water and anhydrous ethanol and dried at 60°C for 10 hours to obtain the P-Sb2S3 / MoS2 composite material.

[0051] Experimental Example 1

[0052] The P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3 was characterized and tested as follows:

[0053] X-ray diffraction (XRD): The X-ray diffraction (XRD) spectrum of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material is as follows Figure 3 As shown, the spectral lines correspond to the crystal structures of Sb2S3 (card number JCPDS: 42-1393) and MoS2 (card number JCPDS: 37-1492).

[0054] Scanning electron microscopy (SEM): The scanning electron microscopy image of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material is as follows Figure 2 As shown, lamellar MoS2 grows uniformly on the surface of rod-shaped Sb2S3, and the size of the P-Sb2S3 / MoS2 heterojunction is between 100nm-1μm.

[0055] Transmission electron microscopy (TEM): The transmission electron microscopy image of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material is as follows Figure 1As shown, the lamellar MoS2 is extremely thin and very stretched, and is well dispersed.

[0056] High-resolution transmission electron microscopy (HRTEM): The high-resolution transmission electron microscopy image of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material is as follows: Figure 4 As shown in the figure, the stripes with a spacing of 0.62 nm correspond to the (002) crystal plane of MoS2, while the stripes with spacings of 0.356 nm, 0.217 nm, and 0.182 nm correspond to the (310), (331), and (022) crystal planes of Sb2S3, respectively. The interface between the two phases is relatively clear. In addition, the lattice fringes at the interface between Sb2S3 and MoS2 appear distorted, forming abundant interface defects.

[0057] Electron paramagnetic resonance spectroscopy (EPR): The electron paramagnetic resonance spectrum of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material is as follows Figure 5 As shown in the figure, the EPR signal of P-Sb2S3 / MoS2 heterojunction is significantly stronger than that of Sb2S3 / MoS2, MoS2 and Sb2S3, indicating that there are abundant sulfur vacancies in the P-Sb2S3 / MoS2 heterojunction electrocatalytic material.

[0058] Raman spectroscopy: The Raman spectrum of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material is as follows: Figure 6 143cm shown -1 and 190cm -1 The peak at 252 cm is attributed to the bending vibration of the S-Sb-S bond. -1 The peak at 295 cm is caused by the stretching vibration of Sb-S-Sb. -1 The stretching vibration peak of Sb-S bond is 448cm -1 The peak at 373 cm corresponds to the stretching vibration of the SS bond. In addition, we can also observe the characteristic peaks of 2H-MoS2 and 1T-MoS2, among which -1 and 402cm -1 The strong peak at corresponds to the 2H-MoS2 plane and out-of-plane A 1g Vibration, 219cm -1 , 282cm -1 , 325cm -1 The peak at is attributed to J2 of 1T-MoS2. J3 vibrates.

[0059] X-ray Photoelectron Spectroscopy (XPS): Figure 7 (a) is the 3d fine spectrum of Mo. There are two different groups of Mo in the spectrum. 4+The 3d peaks are attributed to 1T-MoS2 and 2H-MoS2 respectively. 4+ 3D 5 / 2 and 3D 3 / 2 The orbital peaks are located at 228.96eV and 232.10eV, 2H-MoS2 Mo 4+ 3D 5 / 2 and 3D 3 / 2 The orbital peaks are located at 229.25eV and 232.54eV, and the content of 2H-MoS2 is about twice that of 1T-MoS2. The peaks at 232.89eV and 235.94eV correspond to Mo 6+ 3D 5 / 2 and 3D 3 / 2 Track, this is because the material is exposed to air so that the surface part Mo 4+ The peak near 226eV is assigned to the S2s orbital due to oxidation. Corresponding to two different MoS2, two groups of peaks also appear in the S2p spectrum ( Figure 7 c), located at 161.77eV and 163.39eV, 162.92eV and 164.54eV respectively. Sb 3d fine spectrum ( Figure 7 b) Display Sb 3d 5 / 2 and 3D 3 / 2 The orbital peaks are located at 529.92eV and 539.23eV respectively. 3 / 2 and 2p 1 / 2 The peaks of Mo appear at 130.13eV and 131.27eV. In addition, by comparing the Mo 3d spectra, it can be found that the Mo of P-Sb2S3 / MoS2 4+ The peak of MoS2 moves toward the direction of higher binding energy compared to pure phase MoS2. This is because the formation of heterostructure promotes the establishment of built-in electric field. Since the electronegativity of Mo is higher than that of Sb, electrons migrate from Sb to Mo, which makes Mo 4+ The binding energy of P is positively shifted. The negative shift of Sb 3d peak can also prove this. The electron migration between the two phases is beneficial to improve the conductivity and catalytic activity of the material. In addition, since the electronegativity of P is lower than that of S, the Mo after P doping 4+ The binding energy decreased slightly.

[0060] Experimental Example 2

[0061] The performance test of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material obtained in Example 3 is as follows:

[0062] Electrochemical testing employed a three-electrode system with catalyst-loaded carbon paper as the working electrode, a saturated silver chloride electrode as the reference electrode, and a graphite rod electrode as the auxiliary electrode. Testing was performed in an H-type electrolytic cell, with the cathode and anode compartments separated by a Nafion 211 proton exchange membrane. The electrolyte consisted of a 0.1 M sodium sulfate solution, and all test potentials were converted to reversible hydrogen potential. The working electrode was fully activated by cyclic voltammetry before electrocatalytic testing. High-purity argon and nitrogen were purified with 0.1 M NaOH, 0.05 M H₂SO₄, and H₂O at a flow rate of 30 mL / min. Prior to the start of the experiment, the required gases were pre-circulated for 30 minutes to expel any residual gas from the electrolytic cell. The electrocatalytic process was monitored by chronoamperometry at a constant potential for 2 hours. Ammonia produced during the electrocatalytic process and any potential byproduct, hydrazine, were detected by UV spectrophotometry.

[0063] The P-Sb2S3 / MoS2 heterojunction exhibits good NRR performance in the range of -0.45 to -0.65 V (vs. RHE). Figure 8 In this potential range, the ammonia production rate and Faradaic efficiency both show a trend of increasing first and then decreasing, with the highest value appearing at -0.55 V (vs. RHE), and the corresponding ammonia production rate and Faradaic efficiency are 15.79%, and its ammonia production rates are 2.00 times, 3.59 times, and 4.45 times that of Sb2S3 / MoS2, MoS2, and Sb2S3, respectively.

[0064] Long-term stability is one of the key parameters that determine the practical performance of electrocatalysts. The P-Sb2S3 / MoS2 heterojunction electrocatalyst of Example 3 was subjected to 6 consecutive electrocatalytic experiments, and the Faraday efficiency and ammonia production rate showed only slight changes ( Figure 9 ), indicating its good cyclic stability.

[0065] Selectivity is an important indicator for evaluating catalysts. After detection by UV spectrophotometer, no hydrazine was produced in the electrolyte ( Figure 10 ), indicating that the P-Sb2S3 / MoS2 heterojunction electrocatalyst has good selectivity.

[0066] The current density versus scan rate curve of the electrocatalyst can reflect the double layer capacitance (C dI ) size. Figure 11 It can be seen that the double layer capacitance of the P-Sb2S3 / MoS2 heterojunction electrocatalyst is 1.58mF / cm 2 , higher than Sb2S3 / MoS2, MoS2 and Sb2S3.

[0067] The electrochemical impedance spectroscopy (EIS) was performed using a CHI 760E electrochemical workstation. Other test conditions were kept the same, and the frequency was set from 1000000 Hz to 0.01 Hz. Figure 12 As shown by Figure 12 It can be seen that the P-Sb2S3 / MoS2 heterojunction electrocatalyst has a small electron transfer resistance of 10.5Ω.

[0068] The above examples illustrate that the P-Sb2S3 / MoS2 heterojunction electrocatalytic material has excellent NRR performance.

Claims

1. A high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction (NRR) is synthesized via a continuous hydrothermal method, i.e., rod-shaped Sb2S3 is first hydrothermally synthesized, followed by hydrothermal formation of lamellar MoS2 on the surface of the rod-shaped Sb2S3. A phosphorus source is also introduced in the second hydrothermal step for phosphorus doping, forming a core-shell P-Sb2S3 / MoS2 heterojunction. The material size ranges from 100 nm to 1 μm.

2. The high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 1 is characterized in that: The X-ray diffraction (XRD) spectrum of the material corresponds to the crystal structure of Sb2S3 with the card number JCPDS: 42-1393 and MoS2 with the card number JCPDS: 37-1492; The X-ray photoelectron spectrum of the P-Sb2S3 / MoS2 heterojunction electrocatalytic material shows peaks of four components: Mo 3d, Sb 3d, S2p, and P 2p.

3. The high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 1 comprises abundant interfaces and heterojunction structures, as well as abundant interface defects and sulfur vacancies.

4. The method for preparing the high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 1 comprises the following steps: (1) A certain amount of antimony compound and sulfur compound were dispersed in 50 mL of water. After being stirred for 30 min, the resulting mixture was transferred to a 100 mL polytetrafluoroethylene reactor. After reacting at a suitable temperature for a period of time, the resulting product was washed thoroughly with water and anhydrous ethanol, and then dried at 60 °C for 10 h to obtain product 1. (2) The molybdenum compound and product 1 were dispersed in 60 mL of water in a certain proportion, and appropriate amounts of sulfur compounds and phosphorus compounds were added. After sufficient stirring, the mixture was transferred to a 100 mL polytetrafluoroethylene reactor and fully reacted at a certain temperature. The reaction product was fully washed with water and anhydrous ethanol and dried at 60 °C for 10 h to obtain a high-performance P-Sb2S3 / MoS2 heterojunction electrocatalytic material.

5. The method for preparing the high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 4, characterized in that: The antimony compound in step (1) is antimony trichloride, and the sulfur source is thiourea.

6. The method for preparing the high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 4, characterized in that: The molybdenum compound described in step (2) is ammonium molybdate tetrahydrate, the sulfur compound is thiourea, and the phosphorus compound is sodium dihydrogen phosphate.

7. The method for preparing the high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 4, characterized in that: The molar ratio of the antimony compound to the sulfur compound in step (1) is controlled to be 1:(2-4).

8. The method for preparing the high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 4, characterized in that: The reaction temperature of the hydrothermal reaction in step (1) is 150-180° C., and the reaction time is 15-30 hours.

9. The method for preparing the high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 4, characterized in that: In step (2), the molar ratio of antimony element to molybdenum element is controlled at (1-3):1, and the molar ratio of phosphorus element to sulfur element is (0.5-2):

10.

10. The method for preparing the high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 4, characterized in that: The reaction temperature of the hydrothermal reaction in step (2) is 180-220°C, and the reaction time is 10-24 hours.

11. Use of the high-performance heterojunction catalytic material P-Sb2S3 / MoS2 for electrocatalytic nitrogen reduction according to claim 1 in the electrocatalytic reduction of nitrogen to ammonia, using a three-electrode system, an electrolyte of 0.1 M Na2SO4, and a test potential range of -0.45 to -0.65 V vs. RHE; when the potential is -0.55 V vs. At RHE, the ammonia production rate reaches , the Faraday efficiency is 15.79%.

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