A preparation method of layered molybdenum-based nanosheet assembled based on two-dimensional transition metal boride and 1T-MoS2
By employing the electrostatic self-assembly of Mo4/3B2 and 1T-MoS2 in the preparation method, the thermodynamic instability and agglomeration of 1T-MoS2 were resolved, resulting in layered molybdenum-based nanosheets with high phase purity, good dispersibility, and high structural stability, thereby enhancing electrocatalytic performance.
Patent Information
- Application Number
- CN202611508317.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-28
- Publication Date
- 2026-11-03
AI Technical Summary
In the existing technology, 1T-MoS2 is thermodynamically unstable and is prone to spontaneous phase transition to the 2H phase. Furthermore, due to the weak van der Waals forces between the layers, the two-dimensional material is prone to spontaneous aggregation, which leads to a reduction in active sites and hinders ion transport, making it difficult to obtain products with high phase purity and high structural stability.
Two-dimensional Mo4/3Y2/3AlB2 was prepared by assembling quaternary transition metal boride precursors Mo4/3Y2/3AlB2 with 1T-MoS2 via HF etching and TMAOH intercalation. 1T-MoS2 was generated by high-temperature annealing and NaCl flux. PDDA was used to positively modify 1T-MoS2. Mo4/3B2 and 1T-MoS2 were then spontaneously assembled by electrostatic attraction to form layered molybdenum-based nanosheets.
The transformation of 1T-MoS2 to the 2H phase was successfully suppressed, the stability of the 1T phase was maintained, the aggregation of nanosheets was inhibited, charge transport and active sites were improved, and the electrocatalytic performance was enhanced. Moreover, the preparation process is simple and suitable for large-scale production.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of inorganic nanomaterial preparation technology, specifically relating to a method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2. Background Technology
[0002] Two-dimensional layered transition metal dichalcogenides have become a research hotspot in the field of electrocatalysis due to their unique two-dimensional structure, abundant surface active sites, and tunable physicochemical properties. Molybdenum disulfide (Mo2S), as a typical representative of transition metal dichalcogenides, possesses advantages such as environmental friendliness, abundant crustal reserves, and a wide range of tunable performance. Mo2S crystals exist in multiple phases, among which the 2H phase is thermodynamically stable, exhibiting a triangular prism-coordinated semiconductor structure with poor intrinsic conductivity and active sites confined to the edges. The metastable 1T phase possesses metallic properties, exhibiting excellent electronic conductivity, hydrophilicity, and larger interlayer spacing, which is beneficial for rapid electrolyte wetting and electron transfer, showing broad application prospects in electrocatalysis, metal-ion batteries, and supercapacitors. However, the incomplete occupancy of electron orbitals leads to thermodynamic instability in the 1T phase of Mo2S, making it prone to spontaneous phase transition to the stable 2H phase during preparation or storage. This inherent defect makes it difficult to obtain products with high phase purity and high structural stability, becoming a key bottleneck restricting its large-scale application. Furthermore, two-dimensional materials are prone to spontaneous aggregation due to the weak van der Waals forces between layers, which severely reduces active sites and hinders ion transport, ultimately leading to a significant decrease in material performance. Existing technologies typically employ hybridization with MXene or the introduction of boron to improve the conductivity and stability of the 1T phase molybdenum disulfide system. However, existing composite schemes have limited stabilizing effects on the 1T phase molybdenum disulfide, and the preparation processes are complex, making it difficult to simultaneously achieve high phase purity, good dispersibility, and large-scale preparation.
[0003] Therefore, the lack of a method for preparing layered molybdenum-based nanosheets that can effectively stabilize 1T phase molybdenum disulfide, inhibit nanosheet aggregation, and has a simple preparation process has become a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0004] The technical problem to be solved by this invention is that the existing 1T-MoS2 is thermodynamically unstable and is prone to spontaneous phase transition to the 2H phase during preparation or storage, making it difficult to obtain products with high phase purity and high structural stability. At the same time, the two-dimensional material is prone to spontaneous aggregation due to the weak van der Waals forces between the layers, which seriously reduces the active sites and hinders ion transport, resulting in a decline in material performance.
[0005] To address the aforementioned technical problems, this invention provides a method for preparing layered molybdenum-based nanosheets assembled from two-dimensional transition metal borides and 1T-MoS2, comprising the following steps: Step S100, the quaternary transition metal boride precursor Mo 4 / 3Y 2 / 3 AlB2 was selectively etched with HF and intercalated with TMAOH to obtain two-dimensional Mo. 4 / 3 B2; Step S200: The ternary transition metal boride MoAlB, alkali metal sulfide Na2S, and flux NaCl are ball-milled and mixed evenly, then annealed at high temperature, and then placed in acid and alkali solutions for alternating ultrasonic washing and centrifugation to remove impurities, to obtain two-dimensional 1T-MoS2. Step S300: The 1T-MoS2 obtained in step S200 is positively modified with PDDA to make the surface of 1T-MoS2 positively charged. The two-dimensional Mo obtained in step S100 is then... 4 / 3 B2 is added to the modified 1T-MoS2, driving Mo through electrostatic attraction. 4 / 3 B2 and 1T-MoS2 spontaneously assembled, and after centrifugation and washing, layered molybdenum-based nanosheets were obtained.
[0006] Further, step S100 includes: Step S110, weigh Mo 4 / 3 Y 2 / 3 AlB2 powder was added to an HF solution and reacted in an oil bath. HF selectively etched Mo. 4 / 3Y 2 / 3 After the reaction of AlB2 with Al and Y layers, the precipitate was washed with deionized water by centrifugation to obtain multilayered Mo. 4 / 3 B2 precipitation; Step S120, applying the material to the multilayer Mo 4 / 3 A mixed solution of TMAOH and deionized water was added to the B2 precipitate, and the mixture was treated on a shaker. The TMAOH then intercalated into the Mo... 4 / 3 Between B2 floors, the interlayer spacing is increased; Step S130: Add anhydrous ethanol to the intercalated mixture, centrifuge and wash, collect the precipitate, add deionized water, centrifuge at 3000 rpm, collect the upper black solution, freeze-dry to obtain monolayer Mo. 4 / 3 B2 powder.
[0007] Further, in step S110, the mass fraction of HF is 40 wt%, the etching temperature is 40℃, and the etching time is 24 hours. Further, in step S120, the mass fraction of TMAOH is 25 wt%, the volume ratio of TMAOH to deionized water is 1:1, and the shaking treatment time is 1 h.
[0008] Further, step S200 includes: Step S210: Weigh NaCl, MoAlB, and Na2S and place them in a ball mill jar. Mix them evenly by ball milling to obtain a mixed powder. Step S220: The mixed powder is placed in a tube furnace and annealed at 700°C at a rate of 5°C / min in a N2 / H2 (5%) gas flow. The mixture is held at this temperature for 4 h. During the annealing process, Na2S and MoAlB undergo a high-temperature molten displacement reaction. NaCl acts as a flux to promote the reaction and generate 1T-MoS2. Step S230: The powder obtained after annealing is added to hydrochloric acid solution and deionized water for ultrasonic treatment, centrifuged at 9000 rpm, and the precipitate is collected. The precipitate is dissolved in a mixed solution of hydrochloric acid solution, n-butylamine, deionized water and isopropanol, and ultrasonically washed alternately. The powder is then centrifuged at 9000 rpm and 1T-MoS2 black powder is collected.
[0009] Further, in step S210, the amount of NaCl is 8.00 g, the amount of MoAlB is 0.10 g, the amount of Na2S is 0.60 g, the ball milling frequency is 20 Hz, and the ball milling time is 40 min.
[0010] Further, in step S230, the concentration of the hydrochloric acid solution is 4 M, the volume is 10 mL, and the ultrasonic time is 20 min; the volume ratio of hydrochloric acid solution, n-butylamine, deionized water, and isopropanol in the mixed solution of alternating ultrasonic washing is 2:2:1, and each is alternately ultrasonically washed twice.
[0011] Further, step S300 includes: Step S310: Weigh 1T-MoS2, dissolve it in deionized water, disperse it by ultrasonication, add PDDA, sonicate it, stir it, PDDA acts as a positive charge donor and adsorbs onto the surface of 1T-MoS2, making the surface of 1T-MoS2 positively charged, stir it, add deionized water to wash it, take the precipitate and add deionized water, and record it as solution A. Step S320, weigh Mo 4 / 3 B2, dissolved in deionized water and ultrasonically dispersed, is denoted as solution B; In step S330, solution B is slowly added to solution A using a dropper, and the mixture is stirred. After the reaction is complete, the mixture is centrifuged at 9000 rpm to collect the black MBene / 1T-MoS2 nanosheets.
[0012] Further, in step S310, the amount of 1T-MoS2 is 0.05 g, the amount of deionized water is 10 mL, the sonication time is 40 min, the amount of PDDA is 1 mL, the sonication time is 40 min, and the stirring time is 4 h; in step S320, Mo 4 / The amount of 3B2 used was 0.05 g, the amount of deionized water was 10 mL, and the ultrasonic time was 40 min; in step S330, the stirring time was 24 h.
[0013] Furthermore, in step S300, when deionized water, H2SO4, HNO3, HCl or HF are used to replace PDDA, 1T-MoS2 is transformed into the 2H phase, and stable layered molybdenum-based nanosheets cannot be obtained; when PDDA is positively modified, the (002) peak of the assembled 1T-MoS2 shifts from 8.6° to 7.9°, the 1T phase of 1T-MoS2 is stabilized, and the resulting MBene / 1T-MoS2 has an HER overpotential of 121 mV at 10 mA / cm².
[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) By positively modifying 1T-MoS2 with PDDA, the surface of 1T-MoS2 is changed from negatively charged to positively charged, which interacts with the negatively charged Mo 4 / 3 Electrostatic attraction is generated between B2 particles, driving them to spontaneously and orderly stack and assemble, thus realizing Mo 4 / 3 Uniform composite of B2 and 1T-MoS2. (2) Through Mo 4 / 3 B2, acting as a stable framework, assembles with 1T-MoS2, suppressing the metastable transformation of 1T-MoS2 to the 2H phase. After assembly, the (002) peak of 1T-MoS2 shifts from 8.6° to 7.9°, the interlayer spacing increases, and the 1T phase is successfully stabilized. (3) By inhibiting the pre-agglomeration of nanosheets in the liquid system through electrostatic repulsion, MBene / 1T-MoS2 is kept well dispersed, avoiding the reduction of active sites and the obstruction of ion transport caused by agglomeration. (4) By using Mo 4 / 3 The synergistic effect of B2 and 1T-MoS2 improves charge transport and increases active sites. MBene / 1T-MoS2 at 10 mA / cm 2 The HER overpotential is only 121 mV, which is better than Mo. 4 / 3 The electrocatalytic performance of B2 is 213 mV and that of 1T-MoS2 is 153 mV, which significantly improves the performance. (5) Through the electrostatic attraction self-assembly strategy, the preparation conditions are mild, no harsh anhydrous and oxygen-free environment and dangerous reagents are required, the preparation process is simple and suitable for large-scale preparation. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the preparation method of the layered MBene / 1T-MoS2 nanosheets described in this invention.
[0016] Figure 2 The precursor Mo in Example 1 4 / 3 Y 2 / 3 XRD pattern of AlB2 powder.
[0017] Figure 3 The monolayer Mo in Example 1 4 / 3 XRD pattern of B2 powder.
[0018] Figure 4 The precursor Mo in Example 1 4 / 3 Y 2 / 3 ICP-MS image of AlB2 powder.
[0019] Figure 5 The monolayer Mo in Example 1 4 / 3 ICP-MS image of B2 powder.
[0020] Figure 6 The monolayer Mo in Example 1 4 / 3 TEM image of B2.
[0021] Figure 7 The image shows the XRD pattern of the 1T-MoS2 powder in Example 1.
[0022] Figure 8 The image shows the Raman spectrum of the 1T-MoS2 powder in Example 1.
[0023] Figure 9 This is a TEM image of the 1T-MoS2 powder in Example 1.
[0024] Figure 10 The image shows the ICP-MS pattern of 1T-MoS2 powder in Example 1.
[0025] Figure 11 Mo in Example 1 4 / 3 Zeta potential diagrams of B2, 1T-MoS2 and modified 1T-MoS2.
[0026] Figure 12 Mo in Example 1 4 / 3 XRD patterns of B2, 1T-MoS2 and MBene / 1T-MoS2.
[0027] Figure 13 This is a SEM image of MBene / 1T-MoS2 in Example 1.
[0028] Figure 14 This is a TEM image of MBene / 1T-MoS2 in Example 1.
[0029] Figure 15 Mo in Example 1 4 / 3 LSV curves of B2, 1T-MoS2 and MBene / 1T-MoS2.
[0030] Figure 16 The image shows the XRD pattern of the product from Example 2.
[0031] Figure 17 The image shows the Raman spectrum of the product from Example 2.
[0032] Figure 18 This is an SEM image of the product from Example 2.
[0033] Figure 19 The image shown is the XRD pattern of the product from Example 3.
[0034] Figure 20 The image shows the Raman spectrum of the product in Example 3.
[0035] Figure 21 The image shown is the XRD pattern of the product from Example 4.
[0036] Figure 22 The image shows the Raman spectrum of the product in Example 4.
[0037] Figure 23 The image shown is the XRD pattern of the product from Example 5.
[0038] Figure 24 The image shows the Raman spectrum of the product from Example 5.
[0039] Figure 25 The image shown is the XRD pattern of the product from Example 6.
[0040] Figure 26 The image shows the Raman spectrum of the product from Example 6. Detailed Implementation
[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0042] Reference Figure 1 The present invention provides a method for preparing layered molybdenum-based nanosheets assembled from two-dimensional transition metal borides and 1T-MoS2, comprising the following steps: Step S100: Preparation of two-dimensional MBene; Step S200, Preparation of 1T-MoS2; Step S300: Electrostatic self-assembly to prepare layered molybdenum-based nanosheets.
[0043] The specific implementation methods of each step are explained in detail below with reference to the accompanying drawings.
[0044] Step S100: Preparation of two-dimensional MBene; Step S100 uses the quaternary transition metal boride precursor Mo 4 / 3 Y 2 / 3 Using AlB2 as a raw material, the process further includes the following sub-steps: Step S110, weigh Mo 4 / 3 Y 2 / 3AlB2 powder was added to an HF solution and reacted in an oil bath. HF selectively etched Mo. 4 / 3Y 2 / 3 After the reaction of AlB2 with Al and Y layers, the precipitate was washed with deionized water by centrifugation to obtain multilayered Mo. 4 / 3 B2 precipitation; Step S120, applying the material to the multilayer Mo 4 / 3 A mixed solution of TMAOH and deionized water was added to the B2 precipitate, and the mixture was treated on a shaker. The TMAOH then intercalated into the Mo... 4 / 3 Between B2 floors, the interlayer spacing is increased; Step S130: Add anhydrous ethanol to the intercalated mixture, centrifuge and wash, collect the precipitate, add deionized water, centrifuge at 3000 rpm, collect the upper black solution, freeze-dry to obtain monolayer Mo. 4 / 3 B2 powder.
[0045] The considerations for using steps S110 to S130 are as follows: HF selective etching can remove Mo. 4 / 3 Y 2 / 3 The Al and Y elements in AlB2 retain the Mo-B layer structure, forming a two-dimensional MBene. TMAOH intercalation further widens the interlayer spacing and weakens interlayer van der Waals forces, which is beneficial for obtaining monolayer nanosheets. Freeze-drying avoids the recombination of nanosheets during the drying process.
[0046] Step S200, Preparation of 1T-MoS2; Step S200, using ternary transition metal borides MoAlB, alkali metal sulfides Na2S, and flux NaCl as raw materials, further includes the following sub-steps: Step S210: Weigh NaCl, MoAlB, and Na2S and place them in a ball mill jar. Mix them evenly by ball milling to obtain a mixed powder. Step S220: The mixed powder is placed in a tube furnace and annealed at 700 °C at a rate of 5 °C / min in a N2 / H2 (5%) gas flow. The mixture is held at this temperature for 4 h. During the annealing process, Na2S and MoAlB undergo a high-temperature molten displacement reaction. NaCl acts as a flux to promote the reaction and generate 1T-MoS2. Step S230: The powder obtained after annealing is added to hydrochloric acid solution and deionized water for ultrasonic treatment, centrifuged at 9000 rpm, and the precipitate is collected. The precipitate is dissolved in a mixed solution of hydrochloric acid solution, n-butylamine, deionized water and isopropanol, and ultrasonically washed alternately. The powder is then centrifuged at 9000 rpm and 1T-MoS2 black powder is collected.
[0047] The considerations for using steps S210 to S230 are as follows: the high-temperature molten displacement reaction can achieve the phase transformation of MoAlB to 1T-MoS2; NaCl acts as a flux to lower the reaction temperature; and Na2S provides the sulfur source. Acid washing and alternating acid-base washing can effectively remove residual Na2S and reaction byproducts, obtaining high-purity 1T-MoS2 product.
[0048] Step S300: Electrostatic self-assembly to prepare layered molybdenum-based nanosheets; Step S300 uses the monolayer Mo obtained in step S130 4 / 3 Using 1T-MoS2 obtained from B2 and step S230 as raw materials, the process further includes the following sub-steps: Step S310: Weigh 1T-MoS2, dissolve it in deionized water, disperse it by ultrasonication, add PDDA, sonicate it, stir it, PDDA acts as a positive charge donor and adsorbs onto the surface of 1T-MoS2, making the surface of 1T-MoS2 positively charged, stir it, add deionized water to wash it, take the precipitate and add deionized water, and record it as solution A. Step S320, weigh Mo 4 / 3 B2, dissolved in deionized water and ultrasonically dispersed, is denoted as solution B; In step S330, solution B is slowly added to solution A using a dropper, and the mixture is stirred. After the reaction is complete, the mixture is centrifuged at 9000 rpm to collect the black MBene / 1T-MoS2 nanosheets.
[0049] The considerations for using steps S310 to S330 are as follows: 1T-MoS2 itself is negatively charged, and it interacts with the negatively charged Mo... 4 / 3 When B2 is mixed, it cannot be effectively assembled due to electrostatic repulsion. After positive modification with PDDA, the surface of 1T-MoS2 becomes positively charged, which interacts with the negatively charged Mo. 4 / 3 Electrostatic attraction arises between B2 particles, driving them to spontaneously and orderly stack. Zeta potential test results ( Figure 11 ) shows that Mo 4 / 3 The Zeta potential of B2 is -25 mV, that of 1T-MoS2 is -16.2 mV, and that of the modified 1T-MoS2 is +23.2 mV, proving that PDDA modification changes the surface charge of 1T-MoS2 from negative to positive. After assembly, the (002) peak of 1T-MoS2 shifts from 8.6° to 7.9°. Figure 12 This proves that the interlayer spacing of 1T-MoS2 is increased, and Mo 4 / 3 B2 insertion stabilized 1T-MoS2 in the interlayer.
[0050] Example 1, this example corresponds to steps S100 to S300. Step S110, weigh 0.5 g Mo 4 / 3 Y 2 / 3AlB2 was reacted with 12.5 mL of 40 wt% HF in an oil bath at 40 °C for 24 hours. After the reaction, the precipitate was washed with deionized water by centrifugation to obtain multilayered Mo. 4 / 3 B2 precipitation. Step S120, to multilayer Mo 4 / 3 Add 5 mL of a mixture of 25 wt% tetramethylammonium hydroxide and 5 mL of deionized water to B2, and treat on a shaker for 1 h. In step S130, add anhydrous ethanol to the mixture, centrifuge and wash three times, collect the precipitate, add 12.5 mL of deionized water, centrifuge at 3000 rpm for 15 min, collect the supernatant and freeze-dry to obtain a black powdery monolayer Mo. 4 / 3 B2. Step S210: Weigh 8.00 g NaCl, 0.10 g MoAlB, and 0.60 g Na2S into a ball mill jar and ball mill at 20 Hz for 40 min to obtain a uniformly mixed powder. Step S220: Place the uniformly mixed powder into a tube furnace and anneal it at 700 ℃ in a N2 / H2 (5%) gas stream at a rate of 5 ℃ / min, and hold at this temperature for 4 h. Step S230: Add the annealed powder to hydrochloric acid solution (10 mL 4 M) and 10 mL deionized water, sonicate for 20 min, centrifuge at 9000 rpm, collect the precipitate and dissolve it in a 50 mL mixture of hydrochloric acid solution / n-butylamine, deionized water, and isopropanol (volume ratio 2:2:1), sonicate twice alternately, centrifuge at 9000 rpm, and collect 1T-MoS2 black powder. Step S310: Weigh 0.05 g of 1T-MoS2, dissolve it in 10 mL of deionized water, sonicate for 40 min, add 1 mL of PDDA, sonicate for 40 min, stir for 4 h, wash with deionized water, take the precipitate and add 10 mL of deionized water, and record this as solution A. Step S320: Weigh 0.05 g of Mo... 4 / 3 B2 was dissolved in 10 mL of deionized water and sonicated for 40 min, and this solution was denoted as solution B. In step S330, solution B was slowly added to solution A using a dropper, and the mixture was stirred for 24 h. After the reaction was completed, the mixture was centrifuged at 9000 rpm for 5 min to collect the black MBene / 1T-MoS2 nanosheets. Figure 2 For the precursor Mo 4 / 3 Y 2 / 3 The XRD pattern of AlB2 powder shows four typical characteristic peaks at 11.7°, 23.5°, 32.8°, and 40.7°, which correspond to Mo. 4 / 3 Y 2 / 3 AlB2 (003), (006), (110) and (116) crystal planes. Figure 3 Single-layer Mo 4 / 3The XRD pattern of B2 powder shows the precursor Mo. 4 / 3 Y 2 / 3 The interlayer diffraction peaks of AlB2 have basically disappeared, which is consistent with the diffraction characteristics of two-dimensional materials. Figure 4 , Figure 5 ICP-MS data indicate that the precursor Mo has been largely removed. 4 / 3 Y 2 / The Al and Y elements of 3AlB2 prove that Mo 4 / 3 Synthesis of B2. Figure 6 for Mo 4 / 3 The TEM image of B2 shows that the product is a single-layer nanosheet. Figure 7 The XRD pattern of 1T-MoS2 powder shows four typical characteristic peaks at 8.6°, 17.4°, 32.2°, and 35.3°. These peaks match the (002), (004), (100), and (102) crystal planes of monolayer 1T-MoS2, respectively, proving the synthesis of 1T-MoS2 without other impurities. Figure 8 The Raman spectrum of 1T-MoS2 shows the A1g mode of 1T phase lattice vibration, as well as the E1g, J3, J2 and J1 modes belonging to the symmetric octahedral coordination of molybdenum, indicating the symmetric octahedral coordination of 1T-MoS2. Figure 9 The TEM image of 1T-MoS2 shows that the product is a single-layer nanosheet. Figure 10 ICP-MS data indicate that the B element in the raw material has been completely removed from the synthesized 1T-MoS2. Figure 11 for Mo 4 / 3 Zeta potential diagrams of B2, 1T-MoS2, and modified 1T-MoS2, by Figure 11 It can be seen that both precursors are negatively charged, while the modified 1T-MoS2 is positively charged. Figure 12 for Mo 4 / 3 XRD patterns of B2, 1T-MoS2 and assembled molybdenum-based nanosheets, where the typical diffraction peaks (002) and (004) of 1T-MoS2 shift to 7.9° and 15.8°, respectively, proving that the 1T phase was successfully stabilized and successfully assembled with the two-dimensional boride. Figure 13 , Figure 14 The images show SEM and TEM images of molybdenum-based nanosheets, indicating that the assembled product is a layered nanosheet. Figure 15 for Mo 4 / 3 HER linear sweep voltammetry (LSV) of B2, 1T-MoS2 and MBene / 1T-MoS2 shows that at a current density of 10 mA / cm²... 2 When, Mo 4 / 3The required overpotential for B2 is 213 mV, for 1T-MoS2 it is 153 mV, and for the assembled layered molybdenum-based nanosheets it is 121 mV, indicating that MBene / 1T-MoS2 has good electrocatalytic performance.
[0051] Example 2 follows the same process as Example 1, except that an equal amount of deionized water is added to 1T-MoS2 to replace PDDA. Figure 16 The XRD pattern of the product prepared in Example 2 is shown below. Figure 16 It can be seen that the MoS2 in the product contains both 1T phase and 2H phase components, proving that 1T-MoS2 is partially transformed into 2H phase. Figure 17 The Raman spectrum also includes peaks for the 1T and 2H phases. Figure 18 The SEM image of the product shows that the product morphology is agglomerated and consists of relatively thick nanosheets.
[0052] Example 3 follows the same process as Example 1, except that the type of positive charge donor added to 1T-MoS2 is changed to H2SO4. Figure 19 The XRD pattern of the product prepared in Example 3 is shown below. Figure 19 It can be seen that the peak position of the product is not significantly different from that of 2H-MoS2, proving that 1T-MoS2 is transformed into the 2H phase. Figure 20 The Raman spectrum also shows obvious characteristics of 2H-MoS2.
[0053] Example 4 follows the same process as Example 1, except that the type of positive charge donor added to 1T-MoS2 is changed to HNO3. Figure 21 The XRD pattern of the product prepared in Example 4 is shown below. Figure 21 It can be seen that the crystal phase of the MoS2 component changes at this time, transforming into the 2H phase. Figure 22 The Raman spectrum also shows a distinct 2H phase.
[0054] Example 5 follows the same process as Example 1, except that the type of positive charge donor added to 1T-MoS2 is changed to HCl. Figure 23 The XRD pattern of the product prepared in Example 5 is shown below. Figure 23 It can be seen that the crystal phase of the MoS2 component changes at this time, transforming into the 2H phase. Figure 24 The Raman spectrum also shows a distinct 2H phase.
[0055] Example 6 follows the same process as Example 1, except that the type of positive charge donor added to 1T-MoS2 is changed to HF. Figure 25The XRD pattern of the product prepared in Example 6 is shown below. Figure 25 It can be seen that the crystal phase of the MoS2 component changes at this time, transforming into the 2H phase. Figure 26 The Raman spectrum also shows the 2H phase.
[0056] In Examples 2 to 6, the amount of positive charge donor added, the method of addition, the ultrasonic time, the stirring time, and the subsequent centrifugation and washing conditions were the same as those for PDDA in Example 1, except that the type of positive charge donor was different.
[0057] A comparison of Examples 2 to 6 with Example 1 shows that only by using PDDA as a positive charge donor to positively modify 1T-MoS2 can the interaction between 1T-MoS2 and Mo be achieved. 4 / 3 B2 exhibits electrostatic self-assembly and maintains the stability of the 1T phase of 1T-MoS2 after assembly. When deionized water, H2SO4, HNO3, HCl, or HF are used to replace PDDA, 1T-MoS2 is transformed into the 2H phase, and stable layered molybdenum-based nanosheets cannot be obtained. This comparative result proves that the positively charged modification of PDDA is a necessary technical feature for realizing the technical solution of this invention.
Claims
1. A method for preparing layered molybdenum-based nanosheets assembled from two-dimensional transition metal borides and 1T-MoS2, characterized in that, Includes the following steps: Step S100, the quaternary transition metal boride precursor Mo 4 / 3 Y 2 / 3 AlB2 was selectively etched with HF and intercalated with TMAOH to obtain two-dimensional Mo. 4 / 3 B2; Step S200: The ternary transition metal boride MoAlB, alkali metal sulfide Na2S, and flux NaCl are ball-milled and mixed evenly, then annealed at high temperature, and then placed in acid and alkali solutions for alternating ultrasonic washing and centrifugation to remove impurities, to obtain two-dimensional 1T-MoS2. Step S300: The 1T-MoS2 obtained in step S200 is positively modified with PDDA to make the surface of 1T-MoS2 positively charged. The two-dimensional Mo obtained in step S100 is then... 4 / 3 B2 is added to the modified 1T-MoS2, driving Mo through electrostatic attraction. 4 / 3 B2 and 1T-MoS2 spontaneously assembled, and after centrifugation and washing, layered molybdenum-based nanosheets were obtained.
2. The method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2 according to claim 1, characterized in that, Step S100 includes: Step S110, weigh Mo 4 / 3 Y 2 / 3 AlB2 powder was added to an HF solution and reacted in an oil bath. HF selectively etched Mo. 4 / 3 Y 2 / After the reaction of Al and Y layers in 3AlB2 was completed, the precipitate was washed with deionized water by centrifugation to obtain multilayered Mo. 4 / 3 B2 precipitation; Step S120, applying the material to the multilayer Mo 4 / 3 A mixed solution of TMAOH and deionized water was added to the B2 precipitate, and the mixture was treated on a shaker. The TMAOH then intercalated into the Mo... 4 / 3 Between B2 floors, the interlayer spacing is increased; Step S130: Add anhydrous ethanol to the intercalated mixture, centrifuge and wash, collect the precipitate, add deionized water, centrifuge at 3000 rpm, collect the upper black solution, freeze-dry to obtain monolayer Mo. 4 / 3 B2 powder.
3. The method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2 according to claim 2, characterized in that, In step S110, the mass fraction of HF is 35wt% to 45wt%, the etching temperature is 35°C to 45°C, and the etching time is 20 hours to 28 hours.
4. The method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2 according to claim 2, characterized in that, In step S120, the mass fraction of TMAOH is 20wt% to 30wt%, the volume ratio of TMAOH to deionized water is 1:1 to 1:1.5, and the shaking treatment time is 0.5h to 1.5h.
5. The method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2 according to claim 1, characterized in that, Step S200 includes: Step S210: Weigh NaCl, MoAlB, and Na2S and place them in a ball mill jar. Mix them evenly by ball milling to obtain a mixed powder. In step S220, the mixed powder is placed in a tube furnace and annealed in a N2 / H2 mixed gas with a volume fraction of 5% H2 at a rate of 5°C / min to 650°C to 750°C. The temperature is then maintained at this temperature for 3 to 6 hours. During the annealing process, Na2S and MoAlB undergo a high-temperature molten displacement reaction, with NaCl acting as a flux to promote the reaction, resulting in the formation of 1T-MoS2. Step S230: The powder obtained after annealing is added to hydrochloric acid solution and deionized water for ultrasonic treatment, centrifuged at 9000 rpm, and the precipitate is collected. The precipitate is dissolved in a mixed solution of hydrochloric acid solution, n-butylamine, deionized water and isopropanol, and ultrasonically washed alternately. The powder is then centrifuged at 9000 rpm and 1T-MoS2 black powder is collected.
6. The method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2 according to claim 5, characterized in that, In step S210, the amount of NaCl is 7.5g to 8.5g, the amount of MoAlB is 0.08g to 0.12g, the amount of Na2S is 0.5g to 0.7g, the ball milling frequency is 15Hz to 25Hz, and the ball milling time is 30min to 50min.
7. The method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2 according to claim 5, characterized in that, In step S230, the concentration of the hydrochloric acid solution is 3M to 5M, the volume is 8mL to 12mL, and the ultrasonic time is 15min to 25min; the volume ratio of hydrochloric acid solution, n-butylamine, deionized water, and isopropanol in the mixed solution of alternating ultrasonic washing is 2:2:1, and each is alternately ultrasonically washed 1 to 3 times.
8. The method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2 according to claim 1, characterized in that, Step S300 includes: Step S310: Weigh 1T-MoS2, dissolve it in deionized water, disperse it by ultrasonication, add PDDA, sonicate it, stir it, PDDA acts as a positive charge donor and adsorbs onto the surface of 1T-MoS2, making the surface of 1T-MoS2 positively charged, stir it, add deionized water to wash it, take the precipitate and add deionized water, and record it as solution A. Step S320, weigh Mo 4 / 3 B2, dissolved in deionized water and ultrasonically dispersed, is denoted as solution B; In step S330, solution B is added to solution A using a dropper, and the mixture is stirred. After the reaction is complete, the mixture is centrifuged at 9000 rpm to collect the black MBene / 1T-MoS2 nanosheets.
9. The method for preparing layered molybdenum-based nanosheets based on the assembly of two-dimensional transition metal borides and 1T-MoS2 according to claim 8, characterized in that, In step S310, the amount of 1T-MoS2 is 0.03g to 0.08g, the amount of deionized water is 8mL to 12mL, the sonication time is 30min to 50min, the amount of PDDA is 0.8mL to 1.2mL, the sonication time is 30min to 50min, and the stirring time is 3h to 6h; in step S320, Mo 4 / 3 The amount of B2 used is 0.03g to 0.08g, the amount of deionized water used is 8mL to 12mL, and the ultrasonic time is 30min to 50min; in step S330, the stirring time is 12h to 36h.