A silver-modified bismuthene core-shell material, a silver sulfide-modified bismuthene core-shell material and their preparation method

Abstract

This invention belongs to the field of chemical materials technology and discloses a silver-modified bismuthene core-shell material, a silver sulfide-modified bismuthene core-shell material, and their preparation methods. The preparation method of the silver-modified bismuthene core-shell material includes: preparation of a non-aqueous composite electrolyte; assembly of an electrochemical exfoliation system; electrochemical exfoliation and in-situ coating; and separation and washing of the product. The preparation method of the silver sulfide-modified bismuthene core-shell material includes: dispersion treatment; sulfur source configuration; in-situ conversion; and product separation. This invention constructs unique metal-semiconductor heterojunction and semiconductor-semiconductor heterojunction structures, exhibiting excellent interfacial bonding and stability. The green and efficient "one-pot" preparation process is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of chemical materials technology, specifically to a silver-modified bismuthene core-shell material, a silver sulfide-modified bismuthene core-shell material, and a method for preparing the same. Background Technology

[0002] Bismuthene (i.e., monolayer or few-layer bismuth nanosheets), as a novel two-dimensional topological insulator material, has shown great application potential in quantum devices, catalysis, sensing, and energy storage due to its unique layered structure, high carrier mobility, good biocompatibility, and excellent physicochemical properties. However, the practical application of bismuthene is constrained by two key bottlenecks: firstly, the difficulty in large-scale, high-quality preparation; and secondly, its poor chemical stability, making it prone to oxidative degradation in air (especially humid) environments. To improve the environmental stability of bismuthene, existing technologies typically employ surface encapsulation or passivation strategies. One approach is to coat it with a protective film, but the additional coating may hinder the intrinsic electronic properties of bismuthene and worsen its interfacial transport kinetics in electrochemical applications. Another approach is to construct heterojunctions to modulate its electronic structure and enhance intrinsic stability; however, achieving a tight, uniform combination of two materials at the nanoscale usually requires complex multi-step synthesis and assembly processes, making it difficult to guarantee interface quality and resulting in poor process repeatability.

[0003] Therefore, developing a simple, integrated method that can simultaneously achieve mild and controllable exfoliation, efficient in-situ modification, and ultimately construct a stable heterojunction to enhance the intrinsic stability and optoelectronic properties of bismuthene has become a key technological challenge for promoting the practical application of this material. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for electrochemical cathode stripping and in-situ modification of bismuth nanomaterials. This method prepares bismuth core-shell materials with ultra-small Ag-modified bismuth nanomaterials (Bi core@Ag shell, i.e., metal-semiconductor heterojunction) on the surface, as well as further processed ultra-small Ag2S-modified bismuth core-shell materials (Bi core@Ag2S shell, i.e., semiconductor-semiconductor heterojunction).

[0005] A method for preparing a silver-modified bismuthene core-shell material includes the following steps:

[0006] (1) Preparation of non-aqueous composite electrolyte: Anhydrous dimethyl sulfoxide (DMSO), a non-aqueous solvent, is introduced into a dry electrolytic cell, followed by the addition of an intercalating agent and a precursor salt; the precursor salt is silver acetate or silver nitrate; the mixture is ultrasonically dispersed under continuous stirring until all components are completely dissolved or uniformly dispersed to obtain the composite electrolyte; the electrolyte simultaneously serves as both an "intercalation source" and a "modification source".

[0007] (2) Assembly of the electrochemical stripping system: A block of high-purity bismuth is fixed with a platinum sheet electrode clamp as the working electrode and a platinum wire is used as the counter electrode. The bismuth working electrode is connected to the negative electrode (cathode) of the DC power supply, and the platinum counter electrode is connected to the positive electrode (anode) of the DC power supply. The two electrodes are then immersed in the composite electrolyte prepared in step (1) in parallel and opposite directions.

[0008] (3) Electrochemical stripping and in-situ coating: A constant DC voltage was applied between the bismuth working electrode and the platinum counter electrode to carry out an electrochemical stripping reaction, resulting in a black Ag / Bi nanomaterial colloidal solution.

[0009] Reaction mechanism: Under the drive of a strong electric field, large-size TBAs... + The insertion of cations into the bismuth interlayer causes lattice expansion and exfoliation; simultaneously, Ag... + Ions are reduced to ultra-small silver nanostructures (single atoms or atomic clusters) on the cathode surface and preferentially adsorbed on newly exposed defect sites of bismuthene to form Ag / Bi intermediates (Bi core@Ag shell, i.e. metal-semiconductor heterojunction).

[0010] Reaction phenomena: During the reaction, bubbles are generated on the surface of the working electrode (originating from the reduction and intercalation of ionic liquid cations), causing the bulk bismuth to expand and peel off; at the same time, the solution color gradually darkens, eventually forming a black Ag / Bi nanomaterial colloidal solution.

[0011] (4) Separation and washing of the product: The colloidal solution of Ag / Bi nanomaterials obtained in step (3) is centrifuged, the bottom precipitate is collected and washed multiple times to completely remove the residual electrolyte, and the washed precipitate is vacuum dried at room temperature to obtain silver-modified bismuthene core-shell material.

[0012] Further, in step (1), 20 mL of non-aqueous solvent anhydrous dimethyl sulfoxide is introduced into a dry electrolytic cell, followed by the sequential addition of 40-1000 mg of intercalating agent and 2-40 mg of precursor salt;

[0013] The intercalating agent is a quaternary ammonium salt intercalating agent, wherein the general formula is: [R1R2R3R4]X - Where R1-R4 is C1–C 20 Alkyl, substituted alkyl, allyl, benzyl, aralkyl or combinations thereof; X - The intercalating agent is a halide ion, fluoroborate ion, hexafluorophosphate ion, tetrafluoroborate ion, or bis(trifluoromethanesulfonyl)imide electrolyte anion; or the intercalating agent is a quaternary ammonium salt ionic liquid; or the intercalating agent is a mixture of quaternary ammonium salt intercalating reagent and quaternary ammonium salt ionic liquid;

[0014] The ultrasonic power is 600 W and the ultrasonic time is 3 minutes.

[0015] Furthermore, in step (1), 20 mL of anhydrous dimethyl sulfoxide, a non-aqueous solvent, is introduced into a dry electrolytic cell, followed by the sequential addition of 200 mg of intercalating agent and 10 mg of precursor salt; the intercalating agent is tetrabutylammonium bis(trichloromethanesulfonyl)imide.

[0016] Furthermore, in step (2), the two electrodes are immersed in the composite electrolyte prepared in step (1) in parallel relative to each other, and the electrode spacing is controlled to be 1.0-1.5 cm.

[0017] Furthermore, in step (3), a constant DC voltage of -10V is applied between the bismuth working electrode and the platinum counter electrode to carry out an electrochemical stripping reaction, and the reaction time is 1-6 hours.

[0018] Furthermore, in step (4), the centrifugation speed is 10,000 rpm and the centrifugation time is 10-15 minutes; the vacuum degree of vacuum drying is 6 kPa and the vacuum drying time is 12-24 h.

[0019] The present invention also provides a silver-modified bismuthene core-shell material prepared by the preparation method described above.

[0020] This invention also provides a method for preparing silver sulfide-modified bismuthene core-shell material, comprising the following steps:

[0021] 1) Dispersion treatment: The precipitate after washing in step (4) is dispersed in ethanol and ultrasonically dispersed to obtain a uniform dispersion;

[0022] 2) Sulfur source preparation: Add sodium sulfide nonahydrate to deionized water to prepare a sodium sulfide solution;

[0023] 3) In-situ transformation: Slowly add sodium sulfide solution dropwise to the uniformly dispersed solution described in step 1), and stir overnight at room temperature;

[0024] Transformation mechanism: Utilizing S 2- Its strong nucleophilicity allows for the in-situ conversion of supported Ag single atoms or nanoclusters into Ag₂S. Due to the ultra-small size limitation of the precursor Ag, the final Ag₂S retains the morphological characteristics of the ultra-small nanostructure.

[0025] 4) Separation of products: After stirring, the reaction solution was centrifuged, washed, and finally the precipitate was vacuum dried at room temperature to obtain black silver sulfide modified bismuthene core-shell material.

[0026] Furthermore, in step 1), the amount of ethanol used is the same as the amount of anhydrous dimethyl sulfoxide used in step (1), the ultrasonic power is 600 W, and the ultrasonic time is 5 minutes.

[0027] In step 2), the concentration of the sodium sulfide solution is 1 mg / mL, and the mass ratio of sodium sulfide to the precursor salt in step (1) is 1:2.

[0028] Furthermore, in step 3), the dropping rate is 1 drop / s, the stirring speed is 300 rpm, and the overnight stirring time is 12-24 hours;

[0029] In step 4), the centrifugation speed is 10,000 rpm and the centrifugation time is 10-15 minutes; the vacuum degree of vacuum drying is -1 MPa to -0.9 MPa and the vacuum drying time is more than 12 hours.

[0030] The present invention also provides a silver sulfide-modified bismuthene core-shell material prepared by the preparation method described above.

[0031] The reaction mechanism of Bi core@Ag shell (silver-modified bismuthene core-shell material) and Bi core@Ag2S shell (silver sulfide-modified bismuthene core-shell material) based heterojunction nanomaterials in this invention is as follows:

[0032] Under the condition of applying a negative voltage, the tetrabutylammonium cation (TBA) in the electrolyte... + Bismuth nanoparticles enter the interlayer of bismuth through an ion intercalation mechanism, causing the bismuth layers to expand and eventually be exfoliated into low-dimensional bismuth nanomaterials. The key to this process lies in the effect of an electric field, which enables the layered structure of bismuth to be effectively exfoliated in a short time.

[0033] In the cathode reaction, the electric field simultaneously promotes the reaction of silver ions (Ag). + The reduction of bismuth forms ultra-small Ag nanostructures. These silver nanostructures are nucleated and deposited in situ on the surface of low-dimensional bismuth, and form a tightly bound intermediate (Ag / Bi) (i.e., Bi core@Ag shell) with bismuth through physical / chemical adsorption.

[0034] In the subsequent sulfidation process, the sulfide ions (S ions) in the added sodium sulfide (Na2S) aqueous solution... 2- The silver sulfide undergoes an in-situ chemical transformation with the silver nanoparticles on the surface, forming silver sulfide / bismuth nanomaterials. Due to the size limitation of the silver particles, the generated silver sulfide exhibits a significant ultra-small size effect. Ultimately, a heterojunction material (Bi core@Ag2S shell) is formed, consisting of silver sulfide uniformly loaded on the surface of bismuthene.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] Unique metal-semiconductor heterojunction and semiconductor-semiconductor heterojunction structures were constructed: For the first time, this invention prepared ultra-small-sized metal Ag and ultra-small-sized Ag2S-modified low-dimensional Bi by electrochemical in-situ exfoliation modification strategy, forming core-shell structured heterojunction materials.

[0037] Excellent interfacial bonding and stability: Unlike simple physical mixing, this invention utilizes an in-situ growth strategy to induce strong electronic coupling between Ag or Ag₂S and Bi (confirmed by Raman peak shift). This strong interaction not only reduces interfacial contact resistance but also acts like a "rivet" to passivate the highly active edges of bismuthene, thereby significantly inhibiting the oxidative degradation of low-dimensional bismuth in a water-oxygen environment.

[0038] Green and efficient "one-pot" preparation process: This invention ingeniously couples "electrochemical intercalation and stripping" and "metal ion reduction deposition" in the same electrolytic cell, without the need for high temperature and high pressure, and without the use of any surfactants, ensuring the atomic-level cleanliness of the heterojunction interface, which is suitable for large-scale industrial production. Attached Figure Description

[0039] Figure 1 The results of the stability comparison experiment of Bi core@Ag2S shell, intermediate Ag / Bi (i.e. Bi core@Ag shell) and pure Bi nanomaterial prepared in Example 1 of the present invention in an aqueous environment are shown in the figures. (a) The pure Bi nanomaterial dispersion has been left to stand in water for 24 h; (b) The pure Bi nanomaterial dispersion has been left to stand in water for 10 days; (c) The Ag2S / Bi dispersion has been left to stand in water for 24 h; (d) The Ag2S / Bi dispersion has been left to stand in water for 10 days; (e) The Ag / Bi dispersion has been left to stand in water for 24 h; and (f) The Ag / Bi dispersion has been left to stand in water for 10 days.

[0040] Figure 2 The image shows a comparison of the Raman spectra of bulk bismuth (Bulk Bi), Ag / Bi, and Ag2S / Bi.

[0041] Figure 3 Morphological images (scale bar 50 nm) of the Ag / Bi intermediate (Bi core @ Ag shell) material prepared in Example 1 and corresponding elemental diagrams.

[0042] Figure 4 Morphological photographs (scale bar 5 nm) of the Ag / Bi intermediate material (Bi core @ Ag shell) prepared in Example 1 and corresponding elemental diagrams.

[0043] Figure 5 Morphological photographs (scale bar 100 nm) of the Ag2S / Bi (Bi core @ Ag2S shell) material prepared in Example 1 and corresponding elemental diagrams.

[0044] Figure 6 The results show the stability of the dispersions in different examples. Detailed Implementation

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Example 1

[0047] A method for preparing silver-modified bismuthene core-shell materials includes the following steps:

[0048] (1) Preparation of non-aqueous composite electrolyte: In a dry and ventilated environment, the electrolytic cell was dried in a forced-air drying oven at 70°C for 30 minutes. 20 mL of non-aqueous solvent anhydrous dimethyl sulfoxide (DMSO) was introduced into the dried electrolytic cell, followed by the addition of 200 mg of intercalating agent tetrabutylammonium bis(trichloromethanesulfonyl)imide and 10 mg of precursor salt. The precursor salt was silver acetate. Under continuous stirring, the mixture was ultrasonically dispersed at a power of 600 W for 3 minutes until all components were completely dissolved, thus obtaining the composite electrolyte.

[0049] (2) Assembly of the electrochemical stripping system: A block of high-purity bismuth was fixed with a platinum sheet electrode clamp as the working electrode and a platinum wire as the counter electrode. The electrode and electrode clamp were ultrasonically cleaned in high-purity water and anhydrous ethanol for 5 minutes each. The ultrasonic power was 600W to remove surface oil and impurities. The electrode was then dried in a forced-air drying oven at 70°C for 30 minutes. The bismuth working electrode was connected to the negative electrode (cathode) of the DC power supply, and the platinum counter electrode was connected to the positive electrode (anode) of the DC power supply. The two electrodes were then immersed in the composite electrolyte prepared in step (1) in parallel and opposite directions, with the electrode spacing controlled to be 1.5cm.

[0050] (3) Electrochemical stripping and in-situ coating: A constant DC voltage of -10V was applied between the bismuth working electrode and the platinum counter electrode to carry out an electrochemical stripping reaction. The reaction time was 2 hours, and a black Ag / Bi nanomaterial colloidal solution was obtained.

[0051] (4) Separation and washing of the product: The Ag / Bi nanomaterial colloidal solution obtained in step (3) was centrifuged at a speed of 10,000 rpm for 10 minutes. The bottom precipitate was collected and washed multiple times to completely remove the residual electrolyte.

[0052] Alternating washing: The precipitate is redispersed in the solvent and washed three times in the order of "ethanol-ethanol-ethanol". Each washing process is as follows: first, add solvent and sonicate for 5 minutes, then centrifuge at 10,000 rpm for 10 minutes, and finally discard the supernatant.

[0053] After the final washing, the product was vacuum dried at room temperature under vacuum at a vacuum degree of 6 kPa for 24 hours to obtain silver-modified bismuthene core-shell material (Bi core@Ag shell).

[0054] (5) Dispersion treatment: Repeat steps (1)-(4), disperse the precipitate after washing in step (4) in 20 mL of ethanol, and perform ultrasonic dispersion treatment. The ultrasonic power is 600 W and the ultrasonic time is 5 minutes to obtain a uniform dispersion.

[0055] (6) Sulfur source preparation: Add 5 mg of sodium sulfide nonahydrate to deionized water to prepare a sodium sulfide solution with a concentration of 1 mg / mL;

[0056] (7) In-situ transformation: Sodium sulfide solution was slowly added dropwise to the uniformly dispersed solution in step (5) at a rate of 1 drop / s. The solution was stirred overnight at room temperature at a speed of 300 rpm for 18 hours.

[0057] (8) Separation of products: After stirring, the reaction solution is centrifuged at 10,000 rpm for 10 minutes and the precipitate is washed.

[0058] Alternating washing: The precipitate is redispersed in the solvent and washed three times in the order of "ethanol-ethanol-ethanol". Each washing process is as follows: first, add solvent and sonicate for 5 minutes, then centrifuge at 10,000 rpm for 10 minutes, and finally discard the supernatant.

[0059] After the final washing, the precipitate was vacuum dried at room temperature. The vacuum degree of vacuum drying was -1 MPa to -0.9 MPa, and the vacuum drying time was 12 hours, to obtain black silver sulfide modified bismuthene core-shell material (Bi core@Ag2S shell).

[0060] Figure 1 The stability comparison experiments of the Bi core@Ag2S shell, the intermediate Ag / Bi (i.e., Bi core@Ag shell), and pure Bi nanomaterials prepared according to this invention in an aqueous environment are presented. Figure 1 As shown in Figure (a), pure Bi nanomaterials aggregated into a black precipitate in the aqueous environment within one day. After standing for 10 days, as shown in Figure (a), Figure 1 As shown in Figure (b), the solution is significantly turbid and the precipitate has faded, indicating that the pure Bi nanomaterials have undergone severe oxidative degradation in water. Figure 1 As shown in Figure (c), the Ag2S / Bi (Bi core @ Ag2S shell) nanomaterials slowly settle in water, with the supernatant being colorless and transparent. After standing for 10 days, as... Figure 1As shown in Figure (d), the material has completely precipitated, but the appearance of the precipitate shows no significant change, demonstrating the material's excellent water stability. Figure 1 As shown in Figure (e), the intermediate Ag / Bi (i.e., Bi core @ Ag shell) settles slowly, with stratification only observed in the upper layer. After standing for 10 days, as... Figure 1 As shown in Figure (f), the sedimentation process has ended, the solution is grayish-black, and the precipitate at the bottom shows no color change. These results indicate that Ag-modified and Ag₂S-modified Bi nanomaterials possess excellent chemical stability in water, suggesting that the chemical microenvironment on the Bi surface is well-regulated.

[0061] like Figure 2 As shown, the structural composition of samples from different preparation stages was characterized by Raman spectroscopy. Bulk bismuth (Bulk Bi) was observed at 64.7 cm⁻¹. -1 and 91.2 cm -1 The point shows a sharp E g With A 1g The phonon mode characteristic peaks indicate that the starting material has good crystallinity; in the silver-loaded Ag / Bi intermediate (Bi core@Ag shell), the above bismuth characteristic peaks show a significant frequency shift (shifted to 68.5 cm⁻¹). -1 and 87.4 cm -1 (and in the range of 200-300 cm) -1 The broadened scattering envelope in the region reveals the strong interfacial interaction between Ag species and the Bi substrate and the resulting lattice stress; in the sulfidated Ag2S / Bi (Bi core@Ag2S shell) nanomaterials, the bismuth framework signal remains clear (E g With A 1g The peaks are located at 66.6 cm. -1 and 93.1cm -1 This demonstrates the structural stability of the bismuth nanosheet framework during the preparation process. Notably, the 244.4 cm⁻¹... -1 The newly emerging characteristic peak corresponds to the lattice vibration of monoclinic Ag2S. Due to the phonon confinement effect, the peak exhibits significant broadening and merging characteristics, confirming the successful in-situ growth of ultra-small Ag2S on the bismuth surface and the successful construction of the heterostructure interface.

[0062] like Figure 3As shown, the Ag / Bi intermediate (Bi core@Ag shell) material prepared in the examples exhibits a hierarchical porous structure. The EDS elemental distribution map clearly shows the spatial distribution of Ag (blue) and Bi (red) elements. Notably, the distribution area of ​​Ag elements shows a high degree of spatial consistency with the framework outline of the Bi substrate: Ag elements uniformly cover the entire surface of the Bi nanosheets, and no large-sized (>20 nm) isolated silver particle aggregates or obvious phase separation were observed.

[0063] This result confirms that the electrochemical in-situ reduction process used in this invention successfully achieved highly dispersed loading and conformal growth of Ag species on Bi substrates, effectively avoiding the aggregation problem commonly encountered in traditional liquid-phase reduction, and laying a structural foundation for maximizing the exposure of active sites in the future.

[0064] Figure 4 The image shown is an HRTEM image of the sample (scale bar: 5 nm). The image shows that the material maintains good crystallinity, with clearly visible large-area oriented lattice fringes. Significant contrast differences and moiré patterns were observed at the Ag-Bi interface, confirming a close lattice matching and interfacial coupling between the two phases, rather than simple physical adsorption; this strong interaction is beneficial to improving the structural stability of the composite material during electrochemical cycling.

[0065] Further STEM-EDS elemental analysis revealed that trace amounts of F, N, and S elements derived from the intercalating agent (TBA-TFSI) were conformally distributed and uniformly covered on the bismuthene surface, rather than existing as independent aggregates. This microscopic feature not only confirms the effectiveness of the intercalating agent in the exfoliation of Bi layers, but also indicates that the residual molecules construct a molecular-level protective film through electrostatic or van der Waals forces. The resulting steric hindrance effectively inhibits the recombination of nanomaterials during the drying process and isolates them from water and oxygen erosion, thereby maximizing the preservation of the material's high specific surface area and intrinsic activity.

[0066] like Figure 5 As shown, STEM-EDS characterization results confirmed that the sulfidation treatment successfully induced the construction of an Ag2S@Bi core-shell heterostructure. Bismuth clearly defined the core framework region, while the high spatial overlap between the silver and sulfur signals confirmed that Ag was completely converted to Ag2S in situ. Crucially, the spectrum showed that the generated silver sulfide was in the form of ultra-small nanoscale morphology, uniformly coating the Bi substrate surface with high dispersion. This shell composed of ultra-small Ag2S not only effectively passivated the surface active sites of bismuth, but also provided a solid microstructural foundation for the excellent chemical stability of the composite material in harsh environments by constructing a robust physical barrier.

[0067] Figure 6 The results show the stability of the dispersions in different examples. Compared to Example 1 (Example 1), except... Figure 6 The process parameters are different, but the other steps and parameters are the same.

[0068] like Figure 6 As shown, the system summarizes the effects of different preparation parameters on the aqueous phase stability of the material (measured by the number of days of oxidation discoloration). Compared with Example 1, Examples 2-8 and Comparative Example 1, except for... Figure 6 The process parameters differed, but other steps and parameters remained the same. Comparative results revealed that a single Bi substrate (Comparative Example 1) degraded under environmental conditions in approximately 10 days, while the introduction of the Ag source triggered a qualitative change in stability: even trace doping (2 mg) showed significant effects, and the range of 10-40 mg further established the effectiveness of Ag modification in protecting the substrate over a wide range. At the microstructure control level, although the intercalating agent TBA-TFSI possesses both exfoliation and anchoring functions, its dosage needs precise control: small amounts (40 mg) or excessive amounts (1000 mg) cause changes in ionic strength that affect the macroscopic state, but not the chemical stability. Therefore, 200-400 mg was considered the optimal window for balancing chemical stability and dispersibility. Furthermore, kinetic studies showed that the protective layer formed after 12 hours of sulfidation had slightly lower density, while 18 hours achieved the same excellent antioxidant performance as 24 hours, thus establishing it as the optimal reaction time balancing performance and energy efficiency. The above experimental data strongly confirms that, through the synergistic optimization of key process parameters, this invention has successfully achieved precise customization of the properties of Ag2S / Bi nanomaterials and a significant technological breakthrough.

[0069] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a silver-modified bismuthene core-shell material, characterized in that, Includes the following steps: (1) Preparation of non-aqueous composite electrolyte: Anhydrous dimethyl sulfoxide, a non-aqueous solvent, is introduced into a dry electrolytic cell, followed by the addition of an intercalating agent and a precursor salt; the precursor salt is silver acetate or silver nitrate; the mixture is ultrasonically dispersed under continuous stirring until all components are completely dissolved or uniformly dispersed to obtain the composite electrolyte. (2) Assembly of the electrochemical stripping system: A block of high-purity bismuth is fixed with a platinum sheet electrode clamp as the working electrode and a platinum wire is used as the counter electrode. The bismuth working electrode is connected to the negative terminal of the DC power supply, and the platinum counter electrode is connected to the positive terminal of the DC power supply. The two electrodes are then immersed in the composite electrolyte prepared in step (1) in parallel and opposite directions. (3) Electrochemical stripping and in-situ coating: A constant DC voltage was applied between the bismuth working electrode and the platinum counter electrode to carry out an electrochemical stripping reaction, resulting in a black Ag / Bi nanomaterial colloidal solution. (4) Separation and washing of the product: The colloidal solution of Ag / Bi nanomaterials obtained in step (3) is centrifuged, the bottom precipitate is collected and washed multiple times to completely remove the residual electrolyte, and the washed precipitate is vacuum dried at room temperature to obtain silver-modified bismuthene core-shell material.

2. The method for preparing a silver-modified bismuthene core-shell material according to claim 1, characterized in that, In step (1), 20 mL of non-aqueous solvent anhydrous dimethyl sulfoxide is introduced into a dry electrolytic cell, followed by the addition of 40-1000 mg of intercalating agent and 2-40 mg of precursor salt. The intercalating agent is a quaternary ammonium salt intercalating agent, wherein the general formula is: [R1R2R3R4]X - Where R1-R4 is C1–C 20 Alkyl, substituted alkyl, allyl, benzyl, aralkyl or combinations thereof; X - The intercalating agent is a halide ion, fluoroborate, hexafluorophosphate, tetrafluoroborate, or bis(trifluoromethanesulfonyl)imide electrolyte anion; or the intercalating agent is a quaternary ammonium salt ionic liquid; or the intercalating agent is a mixture of the quaternary ammonium salt intercalating reagent and the quaternary ammonium salt ionic liquid. The ultrasonic power is 600 W and the ultrasonic time is 3 minutes.

3. The method for preparing a silver-modified bismuthene core-shell material according to claim 1, characterized in that, In step (2), the two electrodes are immersed in the composite electrolyte prepared in step (1) in parallel relative to each other, and the electrode spacing is controlled to be 1.0-1.5 cm.

4. The method for preparing a silver-modified bismuthene core-shell material according to claim 1, characterized in that, In step (3), a constant DC voltage of -10V is applied between the bismuth working electrode and the platinum counter electrode to carry out an electrochemical stripping reaction, which takes 1-6 hours.

5. The method for preparing a silver-modified bismuthene core-shell material according to claim 1, characterized in that, In step (4), the centrifugation speed is 10,000 rpm and the centrifugation time is 10-15 minutes; the vacuum degree of vacuum drying is 6 kPa and the vacuum drying time is 12-24 h.

6. A silver-modified bismuthene core-shell material, characterized in that, The silver-modified bismuthene core-shell material is prepared by the preparation method described in any one of claims 1-5.

7. A method for preparing a silver sulfide-modified bismuthene core-shell material, characterized in that, Includes the following steps: 1) Dispersion treatment: The precipitate after washing as described in step (4) of claim 1 is dispersed in ethanol and ultrasonically dispersed to obtain a uniform dispersion; 2) Sulfur source preparation: Add sodium sulfide nonahydrate to deionized water to prepare a sodium sulfide solution; 3) In-situ transformation: Slowly add sodium sulfide solution dropwise to the uniformly dispersed solution described in step 1), and stir overnight at room temperature; 4) Separation of products: After stirring, the reaction solution was centrifuged, washed, and finally the precipitate was vacuum dried at room temperature to obtain black silver sulfide modified bismuthene core-shell material.

8. The method for preparing a silver sulfide-modified bismuthene core-shell material according to claim 7, characterized in that, In step 1), the amount of ethanol used is the same as the amount of anhydrous dimethyl sulfoxide used in step (1) of claim 1, the ultrasonic power is 600 W, and the ultrasonic time is 5 minutes. In step 2), the concentration of the sodium sulfide solution is 1 mg / mL, and the mass ratio of sodium sulfide to the precursor salt in step (1) is 1:

2.

9. The method for preparing a silver sulfide-modified bismuthene core-shell material according to claim 7, characterized in that, In step 3), the dropping rate is 1 drop / s, the stirring speed is 300 rpm, and the overnight stirring time is 12-24 hours; In step 4), the centrifugation speed is 10,000 rpm and the centrifugation time is 10-15 minutes; the vacuum degree of vacuum drying is -1 MPa to -0.9 MPa and the vacuum drying time is more than 12 hours.

10. A silver sulfide-modified bismuthene core-shell material, characterized in that, The silver sulfide-modified bismuthene core-shell material is prepared by the preparation method described in any one of claims 7-9.

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