Preparation method and application of 1T phase molybdenum disulfide quantum dot loaded BN doped guar gum carbon aerogel hydrogen evolution catalyst

Abstract

This invention relates to the field of catalyst technology, and particularly to a method for preparing and applying a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst. The method includes the following steps: First, appropriate amounts of guar gum, boron source, and nitrogen source are weighed and dissolved in deionized water, and allowed to stand at a constant temperature to allow the guar gum to fully expand. Then, an appropriate amount of crosslinking agent is added to form a guar gum hydrogel. After freeze-drying the hydrogel, it is carbonized at high temperature under a nitrogen and argon atmosphere to obtain BN-doped guar gum carbon aerogel. Next, appropriate amounts of molybdenum source and sulfur source are weighed and dissolved in deionized water, stirred evenly, and then added to the above-mentioned BN-doped guar gum carbon aerogel. The carrier is then fully dispersed by magnetic stirring at a constant temperature. Finally, the resulting solution is transferred to a hydrothermal reactor, and the reaction is carried out at a suitable high temperature for a suitable time. The reaction product is centrifuged, washed, vacuum dried, and ultrasonically pulverized to obtain the catalyst. The catalyst prepared by this invention exhibits excellent catalytic performance in the field of water electrolysis for hydrogen evolution.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a method for preparing and applying a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst. Background Technology

[0002] For decades, the world's over-reliance on fossil fuels has exacerbated the dual pressures of energy shortages and environmental pollution, making the development of green and clean renewable energy a core direction for scientific research and industrial innovation. Hydrogen energy, with its ultra-high energy density and zero carbon emissions during combustion, has become the most promising alternative to fossil fuels. Electrochemical water splitting technology is a key means to achieve large-scale, sustainable hydrogen production, with the hydrogen evolution reaction (HER) being the core step in water electrolysis for hydrogen production.

[0003] For a long time, platinum (Pt) and its alloys have been the benchmark catalysts in the HER field due to their near-zero hydrogen adsorption free energy and extremely high intrinsic catalytic activity. However, the extremely low abundance and high price of platinum in the Earth's crust have severely limited its large-scale industrial application. Transition metal disulfides (TMDs) are important candidates for non-noble metal-based HER catalysts, among which molybdenum disulfide (MoS2) has become a research hotspot due to its platinum-like hydrogen adsorption energy at its edge sites. However, traditional MoS2-based catalysts have many inherent defects: First, the thermodynamically stable 2H phase MoS2 is a semiconductor with a band gap of about 1.8 eV and poor electronic conductivity, resulting in slow electron transport between active sites and electrodes; second, the strong van der Waals forces between MoS2 layers easily induce nanosheet aggregation, burying edge active sites and blocking mass transfer channels; third, the proportion of inert basal planes in MoS2 is extremely high, resulting in low utilization of active sites; fourth, the 1T phase MoS2, which has excellent metallic properties and conductivity, is thermodynamically metastable and easily transforms into the 2H phase under electrochemical stress or heat treatment conditions, leading to rapid decay of catalytic activity.

[0004] To address the aforementioned issues, existing technologies employ phase engineering, carbon-based material coupling, and elemental doping strategies for modification. Carbon aerogels, due to their three-dimensional interconnected porous structure, high conductivity, and large specific surface area, are ideal carriers for MoS2. Guar gum, as a green and environmentally friendly natural polysaccharide, is an excellent precursor for preparing carbon aerogels, and its derived carbon aerogels also possess advantages such as abundant surface defects and high carbon yield. However, pure guar gum carbon aerogels lack strong chemical interactions with MoS2, making it unable to stabilize the metastable 1T phase, and the hydrophobic surface reduces electrolyte wettability. The regulatory effect of single heteroatom doping is limited, while boron (B) and nitrogen (N) co-doping can form BCN bonds in the carbon matrix, enhancing the interaction between the carrier and MoS2 through charge redistribution. It can also regulate the hydrogen adsorption energy of MoS2 active sites and improve the hydrophilicity of the carrier. Meanwhile, preparing MoS2 in the form of quantum dots can achieve nearly 100% exposure of edge active sites. However, to date, no study has combined 1T phase MoS2 quantum dots with BN-doped guar gum carbon aerogel, nor has the synergistic modification effect of the two been achieved. Therefore, developing such composite catalysts is a key direction for achieving high performance and low cost of HER catalysts. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for preparing and applying a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst. The catalyst prepared by this invention has the characteristics of excellent conductivity, high 1T phase stability, abundant active sites, and outstanding HER catalytic performance. Moreover, the preparation process is simple, the conditions are mild, and the raw materials are green and environmentally friendly, making it suitable for large-scale preparation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst, the specific steps of which are as follows:

[0008] Step 1: Preparation of BN-doped guar gum carbon aerogel BN-GCA: Weigh an appropriate amount of guar gum, boron source and nitrogen source and dissolve them in deionized water. Let the guar gum swell fully by standing at a constant temperature. Add an appropriate amount of crosslinking agent to form guar gum hydrogel. After freeze-drying the hydrogel, carbonize it at high temperature under nitrogen and argon atmosphere to obtain BN-doped guar gum carbon aerogel.

[0009] Step 2, Preparation of 1T-MoS2QDs@BN-GCA: Weigh appropriate amounts of molybdenum source and sulfur source and dissolve them in deionized water. After stirring evenly, add the above-mentioned BN-doped guar gum carbon aerogel and stir magnetically at a constant temperature to fully disperse the support. Transfer the resulting solution to a hydrothermal reactor and react at high temperature for a period of time. Centrifuge, wash, and vacuum dry the reaction product. After ultrasonic pulverization, obtain the 1T-phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst 1T-MoS2QDs@BN-GCA.

[0010] Preferably, in step 1, the amount of guar gum is 0.2-3.0 g, the amount of boron source is 0.01-0.50 g, the amount of nitrogen source is 0.01-0.50 g, the amount of deionized water is 100-500 g, and the mass fraction of crosslinking agent is 1-10 wt%, with an amount of 1-10 g.

[0011] Preferably, in step 1, the boron source is any one of sodium borate, sodium borohydride, and triphenylboron; the nitrogen source is any one of thiourea, urea, and melamine; and the crosslinking agent is any one of sodium borate, sodium alginate, and epichlorohydrin.

[0012] Preferably, in step 1, the constant temperature is 20~50℃ and the time is 1~5 h; the freeze-drying temperature is -60~-40℃ and the time is 5~20 h; the carbonization temperature is 700~1000℃, the heating rate is 3~10℃·min⁻¹ and the carbonization time is 1~5 h.

[0013] Preferably, in step 2, the molybdenum source is one or more of ammonium molybdate tetrahydrate, sodium molybdate, and ammonium molybdate, the sulfur source is one or more of thiourea, thioacetamide, and sodium hydrosulfide, the molar ratio of the molybdenum source to the sulfur source is 1:(2-14), the volume of the mixed solution of the molybdenum source and the sulfur source is 20-80 mL, and the amount of BN-doped guar gum carbon aerogel is 0.01-0.30 g.

[0014] Preferably, in step 2, the constant temperature magnetic stirring temperature is 20~50℃ and the time is 10~30 h; the hydrothermal reaction temperature is 100~300℃ and the time is 20~40 h; the centrifugal speed is 8000~18000 rpm and the time is 5~15 min; the vacuum drying temperature is 30~65℃ and the time is 20~30 h; and the ultrasonic pulverization time is 5~30 h.

[0015] The present invention also provides an application of the 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst obtained by the above preparation method in the electrochemical hydrogen evolution reaction.

[0016] By adopting the above technical solution, the catalyst has significant advantages including: First, the guar gum carbon aerogel has a three-dimensional interconnected porous structure, providing continuous channels for electron transport and ion diffusion. Its abundant surface defects serve as anchoring sites for MoS2 quantum dots, effectively preventing quantum dot aggregation. Second, the BCN bonds formed by BN co-doping interact strongly with MoS2 quantum dots through charge redistribution, stabilizing the metastable 1T phase MoS2 and preventing its transformation to the 2H phase. This improves electronic conductivity, accelerates electron transport between active sites and electrodes, and optimizes HER catalytic kinetics. Third, MoS2 exists in the form of quantum dots (size less than 10 nm), utilizing the quantum confinement effect to achieve nearly 100% exposure of edge active sites, significantly improving the utilization rate of active sites.

[0017] In 0.5 M H₂SO₄ acidic solution, hydrogen evolution reaction (HER) test results showed that the current density of 1T-MoS₂QDs@BN-GCA could reach 500 mA cm⁻¹. -2 At the same overpotential (380 mV), it is nearly 3.2 times more efficient than 2H-MoS2 (155 mA cm⁻¹). -2 This indicates that the 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst prepared in this invention has good application and commercial prospects. Meanwhile, at 100 mA cm⁻¹... -2 At the specified current density, the HER overpotential of 1T-MoS2QDs@BN-GCA was 135 mV, while that of 2H-MoS2 was 341 mV. At the same current density, a smaller overpotential indicates better catalytic activity. This further demonstrates that the 1T-phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst exhibits superior catalytic activity in HER compared to the 2H-phase MoS2 catalyst. Therefore, this 1T-phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst shows great potential in the field of water electrolysis for hydrogen production under acidic conditions.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst prepared by this invention possesses excellent electrocatalytic hydrogen evolution activity and long-term stability, and can achieve high current density output (HER up to 500 mA cm⁻¹) at low overpotentials. -2 Furthermore, the carrier effect of BN-doped guar gum carbon aerogel synergizes with the activity advantage of 1T phase MoS2 quantum dots, effectively solving the core problems of poor conductivity, easy conversion of 1T metastable phase, insufficient exposure of active sites, and slow electrolyte mass transfer in traditional MoS2-based catalysts. It has great application potential in the field of hydrogen evolution through water electrolysis in acidic electrolyte systems and has broad industrialization prospects.

[0020] 2. The 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst prepared by this invention uses non-precious metals as the core active component and green and environmentally friendly natural guar gum as the carbon source. The preparation process does not require harsh high temperature and high pressure conditions, and can be completed simply by constant temperature stirring and hydrothermal reaction. The process is simple and easy to operate. Compared with traditional 2H phase MoS2-based catalysts, it not only has low preparation cost and environmentally friendly raw materials, but also has better catalytic performance and stability, especially outstanding hydrogen evolution performance under high current density conditions. Attached Figure Description

[0021] Figure 1 TEM image and corresponding EDS elemental distribution map of the 1T-MoS2QDs@BN-GCA sample prepared in Example 1 of the present invention;

[0022] Figure 2 This is a comparison chart of the HER performance of 1T-MoS2QDs@BN-GCA, 2H-MoS2, and 1T-MoS2QDs@GCA samples prepared in 0.5M H2SO4 according to Example 1, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] Preparation method of 1T-MoS2QDs@BN-GCA hydrogen evolution catalyst supported by 1T-phase molybdenum disulfide quantum dots:

[0026] (1) Preparation of BN-doped guar gum carbon aerogel (BN-GCA):

[0027] a) Dissolve 0.7 g guar gum, 0.06 g sodium borate, and 0.06 g thiourea in 200 g deionized water and let stand at 35°C for 3 h to allow the guar gum to fully swell.

[0028] b) Add 2 g of sodium borate aqueous solution with a mass fraction of 3 wt% to the above solution and stir until homogeneous to form guar gum hydrogel.

[0029] c) The hydrogel was placed in an LGJ-10 freeze dryer and freeze-dried at -58℃ for 48 h to obtain guar gum aerogel.

[0030] d) The guar gum aerogel was placed in a tube furnace and heated to 800°C at a heating rate of 5°C·min⁻¹ under a nitrogen atmosphere. After carbonization for 2 h, it was naturally cooled to obtain BN-doped guar gum carbon aerogel.

[0031] (2) Preparation of 1T-MoS2QDs@BN-GCA:

[0032] a) Add 0.14 mmol of ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 Dissolve 2.00 mmol of thiourea (CH4N2S) in 50 mL of deionized water and stir magnetically until completely dissolved.

[0033] b) Add 0.06 g of BN-GCA to the above solution and stir magnetically at 35°C for 12 h to ensure that BN-GCA is fully dispersed in the solution.

[0034] c) Transfer the resulting solution to a 50 mL stainless steel hydrothermal reactor lined with polytetrafluoroethylene and react it hydrothermally at 180 °C for 24 h.

[0035] d) After the reaction was completed, the product was centrifuged at 12,000 rpm for 10 min to obtain a precipitate, which was washed several times with deionized water and anhydrous ethanol alternately, dried under vacuum at 60 °C for 24 h, and sonicated for 24 h to obtain the 1T-MoS2QDs@BN-GCA hydrogen evolution catalyst.

[0036] Comparative Example 1

[0037] Preparation method of 2H phase molybdenum disulfide hydrogen evolution catalyst:

[0038] (1) Preparation of 2H-MoS2:

[0039] a) Add 0.14 mmol of ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 Dissolve 2.00 mmol of thiourea (CH4N2S) in 50 mL of deionized water and stir magnetically until completely dissolved.

[0040] b) Transfer the resulting solution to a 50 mL stainless steel hydrothermal reactor lined with polytetrafluoroethylene and react it hydrothermally at 180°C for 24 h.

[0041] c) After the reaction was completed, the product was centrifuged at 12,000 rpm for 10 min to obtain a precipitate, which was washed several times with deionized water and anhydrous ethanol alternately, and dried under vacuum at 60 °C for 24 h to obtain the 2H-MoS2 hydrogen evolution catalyst.

[0042] Comparative Example 2

[0043] Preparation method of 1T-MoS2QDs@GCA hydrogen evolution catalyst supported by 1T phase molybdenum disulfide quantum dots:

[0044] (1) Preparation of guar gum carbon aerogel (GCA):

[0045] a) Dissolve 0.7 g of guar gum in 200 g of deionized water and let it stand at 35°C for 3 h to allow the guar gum to fully swell.

[0046] b) Add 2 g of sodium borate aqueous solution with a mass fraction of 3 wt% to the above solution and stir until homogeneous to form guar gum hydrogel.

[0047] c) The hydrogel was placed in an LGJ-10 freeze dryer and freeze-dried at -58℃ for 48 h to obtain guar gum aerogel.

[0048] d) The guar gum aerogel was placed in a tube furnace and heated to 800°C at a heating rate of 5°C·min⁻¹ under a nitrogen atmosphere. After carbonization for 2 h, it was naturally cooled to obtain BN-doped guar gum carbon aerogel.

[0049] (2) Preparation of 1T-MoS2QDs@GCA:

[0050] a) Add 0.14 mmol of ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 Dissolve 2.00 mmol of thiourea (CH4N2S) in 50 mL of deionized water and stir magnetically until completely dissolved.

[0051] b) Add 0.06 g GCA to the above solution and stir magnetically at 35°C for 12 h to ensure that GCA is fully dispersed in the solution.

[0052] c) Transfer the resulting solution to a 50 mL stainless steel hydrothermal reactor lined with polytetrafluoroethylene and react it hydrothermally at 180 °C for 24 h.

[0053] d) After the reaction was completed, the product was centrifuged at 12,000 rpm for 10 min to obtain a precipitate, which was washed several times with deionized water and anhydrous ethanol alternately, dried under vacuum at 60 °C for 24 h, and sonicated for 24 h to obtain the 1T-MoS2QDs@GCA hydrogen evolution catalyst.

[0054] Electrochemical testing

[0055] The electrochemical performance of the 1T-MoS2QDs@BN-GCA, 2H-MoS2, and 1T-MoS2QDs@GCA catalysts from Examples 1, 1, and 2 were tested using an electrochemical workstation. The workstation used was a Chenhua CHI 660E electrochemical workstation. The specific methods are as follows:

[0056] 5 mg of catalyst was dispersed in 80 μL of 5 wt% Nafion solution in 920 μL of isopropanol, and the mixture was sonicated for 30 min to obtain a homogeneous suspension. The suspension was then uniformly loaded onto a 1 cm³ plateau. 2 On the carbon paper, the mass loading was 0.28 mg·cm⁻¹. -2 After natural drying, the working electrode was obtained. Using 0.5 M H₂SO₄ as the acidic electrolyte and a three-electrode system, the catalysts prepared in Example 1 (1T-MoS₂QDs@BN-GCA), Comparative Example 1 (2H-MoS₂), and Comparative Example 2 (1T-MoS₂QDs@GCA) were used as the working electrodes, saturated silver chloride as the reference electrode, and a graphite electrode as the counter electrode. Their linear sweep voltammetry curves were tested.

[0057] HER performance testing:

[0058] The HER performance of 1T-MoS2QDs@BN-GCA, 2H-MoS2, and 1T-MoS2QDs@GCA catalysts was tested using linear sweep voltammetry. The obtained HER polarization curves (LSV plots) are shown below. Figure 2 As shown in the figure, the current density of 1T-MoS2QDs@BN-GCA can reach 500 mA cm⁻¹. -2 At the same overpotential (380 mV), it exhibits nearly 3.2 times the performance of 2H-MoS2 (155 mAcm). -2 Meanwhile, at 100 mA cm -2 At the given current density, the overpotential of 1T-MoS2QDs@BN-GCA is 135 mV, while the overpotential of 2H-MoS2 is 341 mV.

[0059] In summary, the 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst prepared by this invention exhibits significantly better hydrogen evolution performance than the 2H phase molybdenum disulfide catalyst. Furthermore, this catalyst demonstrates excellent catalytic activity and stability at high current densities, which is beneficial for its industrial application in the electrolytic hydrogen production industry.

[0060] The descriptions and practices disclosed in this invention are readily apparent and understandable to those skilled in the art, and various modifications and refinements can be made without departing from the principles of this invention. Therefore, any modifications or improvements made without departing from the spirit of this invention should also be considered within the scope of protection of this invention.

Claims

1. A method for preparing a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst, characterized in that, The specific steps are as follows: Step 1: Preparation of BN-doped guar gum carbon aerogel BN-GCA: Weigh an appropriate amount of guar gum, boron source and nitrogen source and dissolve them in deionized water. Let the guar gum swell fully by standing at a constant temperature. Add an appropriate amount of crosslinking agent to form guar gum hydrogel. After freeze-drying the hydrogel, carbonize it at high temperature under nitrogen and argon atmosphere to obtain BN-doped guar gum carbon aerogel. Step 2, Preparation of 1T-MoS2QDs@BN-GCA: Weigh an appropriate amount of molybdenum source and sulfur source and dissolve them in deionized water. After stirring evenly, add the above-mentioned BN-doped guar gum carbon aerogel and stir with magnetic force at constant temperature to fully disperse the carrier. The resulting solution was transferred to a hydrothermal reactor and subjected to a high-temperature hydrothermal reaction for a period of time. The reaction product was centrifuged, washed, vacuum dried, and ultrasonically pulverized to obtain a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst 1T-MoS2QDs@BN-GCA.

2. The preparation method of a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst according to claim 1, characterized in that, In step 1, the amount of guar gum is 0.2-3.0 g, the amount of boron source is 0.01-0.50 g, the amount of nitrogen source is 0.01-0.50 g, the amount of deionized water is 100-500 g, and the mass fraction of crosslinking agent is 1-10 wt%, with an amount of 1-10 g.

3. The preparation method of a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst according to claim 1, characterized in that, In step 1, the boron source is any one of sodium borate, sodium borohydride, and triphenylboron; the nitrogen source is any one of thiourea, urea, and melamine; and the crosslinking agent is any one of sodium borate, sodium alginate, and epichlorohydrin.

4. The preparation method of a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst according to claim 1, characterized in that, In step 1, the constant temperature is 20~50℃ and the time is 1~5 h; the freeze-drying temperature is -60~-40℃ and the time is 5~20 h; the carbonization temperature is 700~1000℃, the heating rate is 3~10℃·min⁻¹, and the carbonization time is 1~5 h.

5. The preparation method of a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst according to claim 1, characterized in that, In step 2, the molybdenum source is one or more of ammonium molybdate tetrahydrate, sodium molybdate, and ammonium molybdate, and the sulfur source is one or more of thiourea, thioacetamide, and sodium hydrosulfide. The molar ratio of the molybdenum source to the sulfur source is 1:(2-14), the volume of the mixed solution of the molybdenum source and the sulfur source is 20-80 mL, and the amount of BN-doped guar gum carbon aerogel is 0.01-0.30 g.

6. The preparation method of a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst according to claim 1, characterized in that, In step 2, the constant temperature magnetic stirring temperature is 20~50℃ and the time is 10~30h; the hydrothermal reaction temperature is 100~300℃ and the time is 20~40h; the centrifugal speed is 8000~18000 rpm and the time is 5~15min; the vacuum drying temperature is 30~65℃ and the time is 20~30h; and the ultrasonic pulverization time is 5~30h.

7. The application of a 1T phase molybdenum disulfide quantum dot-supported BN-doped guar gum carbon aerogel hydrogen evolution catalyst obtained by the preparation method according to any one of claims 1-6 in the electrochemical hydrogen evolution reaction.

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