A bismuth-based nanowire (BSO NW) and a preparation method and application thereof in efficient piezoelectric-optical synergistic catalytic hydrogen evolution
By constructing chiral thin films and Co-doped BCSO NWs piezoelectric-photocatalytic systems using bismuth-based nanowires (BSO NWs), the problem of high recombination rates of photogenerated electron-hole pairs was solved, achieving highly efficient piezoelectric-photosynergistic catalytic hydrogen evolution and improving catalytic efficiency and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGNAN UNIV
- Filing Date
- 2026-05-13
- Publication Date
- 2026-07-24
AI Technical Summary
Existing photocatalytic and piezoelectric catalytic systems suffer from high recombination rates of photogenerated electron-hole pairs and low quantum efficiency, making it difficult to operate continuously in low-light environments. Furthermore, they fail to achieve a deep integration of chiral optical response and piezoelectric effect, thus limiting the efficiency and application range of catalytic hydrogen evolution.
Using bismuth-based nanowires (BSO NWs) and their preparation methods, chiral BSO NWs thin films and BCSO NWs piezoelectric-photocatalytic systems were constructed using LB technology. Combining the chiral structure and piezoelectric effect, piezoelectric polarization generated by ultrasonic vibration was used to promote the separation of photogenerated carriers, achieving efficient catalysis through multi-field coupling.
It significantly improves the catalytic hydrogen evolution activity. Through the spin-selective charge transfer of chiral BSO NWs films and the conduction band electron reduction capability of Co-doped BCSO NWs, it enhances catalytic efficiency and stability, and realizes efficient, intelligent, and polarization-sensitive energy conversion.
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Figure CN122441503A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nanomaterials technology, and in particular to a bismuth-based nanowire (BSO NWs) and its preparation method, as well as its application in highly efficient piezoelectric-photosynergistic catalytic hydrogen evolution. Background Technology
[0002] Hydrogen energy, as a clean, efficient, and renewable energy carrier, is considered an ideal choice for replacing fossil fuels and achieving carbon neutrality. Among numerous hydrogen production technologies, photocatalytic water splitting has attracted much attention due to its advantages such as direct utilization of solar energy, mild reaction conditions, and environmental friendliness. However, traditional photocatalytic systems still face many bottlenecks: high recombination rates of photogenerated electron-hole pairs, low quantum efficiency, and difficulty in continuous operation under low light conditions. These problems restrict the practical application and large-scale development of photocatalytic hydrogen production technology.
[0003] Piezoelectric catalysis, as an emerging energy conversion strategy, offers a new approach to overcoming the inherent limitations of photocatalysis. Piezoelectric materials possess non-centrosymmetric crystal structures and undergo piezoelectric polarization under mechanical stress (such as ultrasonic vibration, water flow, and wind), forming a built-in electric field that drives the directional separation of charge carriers, thereby catalyzing water splitting. Compared to photocatalysis, piezoelectric catalysis has unique advantages: diverse energy forms, utilizing widely available mechanical energy in the environment; not limited by light conditions, enabling hydrogen production in all weather and locations; and most piezoelectric materials are non-toxic, abundant, and inexpensive. Since Hong et al. first reported piezoelectric catalytic hydrogen production from ZnO and BaTiO3 in 2010, this field has developed rapidly, with various materials such as ZnO, CdS, MoS2, and BiOBr exhibiting good piezoelectric catalytic activity. Through strategies such as morphology control, surface modification, and heterostructure construction, the performance of piezoelectric catalysis has been further optimized.
[0004] To overcome the limitations of single catalytic modes, piezoelectric-photocatalysis has emerged. This strategy combines the piezoelectric effect with photoexcitation, utilizing the piezoelectric field to promote the separation of photogenerated carriers, while simultaneously enhancing the piezoelectric polarization intensity, resulting in a synergistic enhancement effect of "1+1>2". Studies have shown that the piezoelectric-photocatalytic system has achieved significantly better catalytic activity than single modes in various materials. Existing hydrogen evolution catalytic systems are mostly limited to single photocatalysis, single piezoelectric catalysis, or simple piezoelectric-photocatalysis, failing to achieve a deep integration of chiral optical response and piezoelectric effect. Summary of the Invention
[0005] To address the above technical problems, this invention provides bismuth-based nanowires (BSO NWs), their preparation method, and their application in efficient piezoelectric-photocatalytic hydrogen evolution. This invention innovatively combines chiral structure, piezoelectric effect, and chiral photocatalysis to construct chiral BSO NWs thin films and a BCSO NWs piezoelectric-photocatalytic system, achieving highly efficient multi-field coupled hydrogen evolution. By precisely controlling the number and angle of nanowire stacking layers using LB technology, LH and RH films with strong chiral optical activity were prepared. Through Co doping to optimize piezoelectric and chiral optical properties, the hydrogen evolution efficiency of the BCSO30 chiral film surpasses that of pure BSO. This work is the first to achieve chiral-piezoelectric-photocatalytic hydrogen production, providing a new template for designing efficient, intelligent, and polarization-sensitive energy conversion materials. This invention utilizes Bi6S2O... 15 The overall lattice features a non-centrosymmetric structure. Under the action of external mechanical stress (such as ultrasonic vibration), the lattice deforms, generating piezoelectric polarization and forming an internal piezoelectric field, which promotes the separation efficiency of electron-hole pairs and catalyzes hydrogen evolution.
[0006] The first objective of this invention is to provide a method for preparing bismuth-based nanowires (BSO NWs), comprising the following steps: The sulfur source, bismuth source, and ammonia water are mixed and dissolved in water, heated and reacted, then cooled to separate the solid and liquid phases and washed to obtain the solid phase, which is the bismuth-based nanowire BSO NWs.
[0007] In some embodiments of the present invention, the sulfur source is selected from sodium sulfate (Na2SO4) and / or potassium sulfate (K2SO4). The bismuth source is selected from bismuth nitrate (Bi(NO3)3·5H2O) and / or bismuth chloride (BiCl3); The molar ratio of the sulfur source to the bismuth source is 1:3 to 3:1; The heating reaction is carried out at a temperature of 150-220℃ for a time of 12-36 h.
[0008] The second objective of this invention is to provide a bismuth-based nanowire (BSO NWs) prepared by the above-described preparation method, which has a bismuth defect shell on its surface.
[0009] A third objective of this invention is to provide a cobalt-doped bismuth-based nanowire BCSO NWs, wherein the bismuth-based nanowire BSO NWs are bulk-doped with cobalt.
[0010] A fourth objective of this invention is to provide a method for preparing the cobalt-doped bismuth-based nanowires, comprising the following steps: The sulfur source, bismuth source, cobalt source and ammonia water are mixed and dissolved in water, heated and reacted, cooled and separated into solid and liquid phases, and washed to obtain the solid phase, which is the bismuth-based nanowire BSO NWs.
[0011] In some embodiments of the present invention, the sulfur source is selected from sodium sulfate (Na2SO4) and / or potassium sulfate; The bismuth source is selected from bismuth nitrate (Bi(NO3)3·5H2O) and / or bismuth chloride; The cobalt source is selected from cobalt chloride CoCl2·2H2O and / or cobalt nitrate; The molar ratio of the cobalt source to the bismuth source is 1:20 to 1:40; The molar ratio of the sulfur source to the bismuth source is 1:3 to 3:1; The heating reaction is carried out at a temperature of 150-220℃ for a time of 12-36 hours.
[0012] The fifth objective of this invention is to provide a chiral BSO NWs thin film, the preparation method of which includes the following steps: A bismuth-based nanowire BSO NWs solution is provided; A bismuth-based nanowire (BSO) NWs solution was injected onto a water surface, and after the solvent evaporated, it was compressed to form a monolayer film; the monolayer film was then transferred to the surface of a substrate. When the surface of a single-layer film is dry, N layers of film are obtained by repeating the transfer N times; and chiral BSO NWs films are obtained by changing the stacking angle θ between the layers.
[0013] In some embodiments of the present invention, the concentration of the bismuth-based nanowire (BSO) NWs solution is 1-20 mg / mL; The stacking angle θ ranges from 0 to 60°.
[0014] The sixth objective of this invention is to provide a chiral BCSO NWs thin film, comprising the following steps: The method for preparing the chiral BCSO NWs thin film comprises the following steps: A bismuth-based nanowire BCSO NWs solution is provided; A bismuth-based nanowire (BSO) NWs solution was injected onto a water surface, and after the solvent evaporated, it was compressed to form a monolayer film; the monolayer film was then transferred to the surface of a substrate. When the surface of the monolayer film is dry, N layers of film are obtained by repeating the transfer N times; and chiral BCSO NWs film is obtained by changing the stacking angle θ between the layers.
[0015] A seventh object of the present invention is to provide the application of the chiral BSO NWs thin film or the chiral BCSO NWs thin film in piezoelectric-photocatalytic synergistic hydrogen evolution.
[0016] The technical solution of the present invention has the following advantages compared with the prior art: This invention utilizes LB film technology to achieve chiral layered stacking of BSO NWs, forming an asymmetric chiral ordered structure. This overcomes the problem of piezoelectric potential cancellation in traditional powder and disordered films, constructing a directional, uniform, and stable in-plane piezoelectric built-in field. Under ultrasonic irradiation, this field can efficiently drive the directional migration of charge carriers, significantly reducing interfacial charge transfer impedance and resulting in catalytic hydrogen evolution activity far exceeding that of disordered and conventional ordered systems. Simultaneously, the chiral stacked BSO NWs film can generate chiral-induced spin-selective charge transfer (CISS), acting as a "spin filter" to achieve spin-selective separation and transport of photogenerated charge carriers, significantly extending carrier lifetime, reducing electron-hole recombination, and providing a more abundant and stable electron supply for the catalytic hydrogen evolution reaction. Co-doped BCSO NWs have a more negative conduction band bottom, significantly enhancing the reduction ability of conduction band electrons while maintaining a suitable band gap, thus providing a more abundant and stable electron supply for H2O. + Reduction to H2 provides a stronger thermodynamic driving force.
[0017] Specifically, this invention provides a Co-doped Bi6S2O with piezoelectric catalytic activity. 15 Chiral BSO NWs (BCSO NWs) were developed for efficient hydrogen evolution. BCSO NWs were synthesized via a hydrothermal reaction and assembled into thin films using the LB technique. Compared to achiral BSO NWs films, chiral BSO NWs films exhibited higher piezoelectric catalytic activity for hydrogen evolution. Furthermore, cobalt doping at a certain proportion further enhanced the hydrogen evolution activity. Based on the chiral structures of both BSO and BCSO NWs films, under light-matched conditions—specifically, left-handed films (LH-films) irradiated with left-handed circularly polarized light (LCP) and right-handed films (RH-films) irradiated with right-handed circularly polarized light (RCP)—the strongest piezoelectric-photosynergistic catalytic effect was observed, further improving the hydrogen evolution rate. Attached Figure Description
[0018] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 The UV-Vis absorption spectrum and infrared spectrum of the BSO NWs prepared in Example 1 of this invention are shown below. Figure 2 The images show scanning electron microscope (SEM) images and particle size analysis diagrams of the BSO NWs prepared in Example 1 of this invention. Figure 3 Scanning electron microscope images of BCSO20 NWs, BCSO30 NWs, and BCSO40 NWs prepared in Example 2 of this invention, and elemental analysis diagram of BCSO30 NWs. Figure 4This is a schematic diagram of the preparation of a chiral BSO NWs membrane in Example 3 of the present invention; Figure 5 The circular dichroism spectrum of the chiral BSO NWs film prepared in Example 3 of this invention is shown. Figure 6 The circular dichroism spectrum of the chiral BCSO NWs film prepared in Example 4 of this invention is shown. Figure 7 The piezoelectric catalytic activity of the BSO NWs membrane measured in Example 5 of this invention; Figure 8 The piezoelectric-photosynergistic hydrogen evolution catalytic activity of the LH / RH-BSO NWs membrane measured in Example 6 of this invention; Figure 9 The piezoelectric catalytic activity of the ordered BCSO NWs membrane measured in Example 7 of this invention; Figure 10 The piezoelectric catalytic activity and piezoelectric-photosynergistic catalytic hydrogen evolution activity of the LH / RH-BCSO30 NWs membrane were measured in Example 8 of this invention. Detailed Implementation
[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.
[0020] Example 1 This embodiment prepares a bismuth-based nanowire (BSO NWs) using the following specific steps: 0.67 mmol Na₂SO₄ and 2 mmol Bi(NO₃)₃·5H₂O were added to 30 mL of distilled water, followed by the addition of 0.5 mL NH₃·H₂O (commercially available, analytical grade, 25%–28%) with stirring. After stirring for another 30 minutes at room temperature, the mixture was transferred to a reaction vessel and reacted in an oven at 180 °C for 24 h. After natural cooling to room temperature, the white precipitate was washed twice with distilled water and ethanol, respectively. The white precipitate was dried at 60 °C to obtain bismuth-based nanowires (BSO₄ NWs). The structure of the obtained product was characterized, and the results are shown below. Figures 1-2 .
[0021] like Figure 1 As shown, slender BSO nanowires with diameters of 50-250 nm were prepared.
[0022] like Figure 2 As shown, BSO NWs have a broad UV-Vis absorption range of 200 nm to 400 nm, and the infrared spectrum indicates that sulfur exists mainly in the form of sulfate in BSO NWs.
[0023] Example 2 This embodiment prepares cobalt-doped bismuth-based nanowires (BCSO NWs), and the specific steps are as follows: 0.67 mmol Na₂SO₄, 2 mmol Bi(NO₃)₃·5H₂O, and a certain amount of CoCl₂·2H₂O (the molar ratios of CoCl₂·2H₂O to Bi(NO₃)₃·5H₂O were 1:20, 1:30, and 1:40, respectively) were added to 30 mL of distilled water, followed by stirring with 0.5 mL of NH₃·H₂O. After stirring for another 30 minutes at room temperature, the mixture was transferred to a reaction vessel and reacted in an oven at 180 °C for 24 h. After naturally cooling to room temperature, the gray precipitate was washed twice with distilled water and ethanol, respectively. The gray precipitate was dried at 60 °C to obtain the final products BCSO₂₀ NWs, BCSO₃₀ NWs, and BCSO₄₀ NWs. The obtained products were characterized by elemental analysis, and the results are shown in the figure. Figure 3 .like Figure 3 As shown, the prepared cobalt-doped bismuth-based nanowires contain Bi, Co, S, and O elements.
[0024] Example 3 This embodiment prepares a chiral BSO NWs thin film, and the specific steps are as follows: The dried BSO NWs obtained in Example 1 were redispersed in a mixed solution of hexane and ethanol (volume ratio 1:1) to obtain a final concentration of 5 mg / mL. The BSO NWs solution was injected onto a square surface of water using a syringe, and a monolayer was formed after the solvent evaporated. The surface monolayer was then slowly compressed to increase the surface molecular density, and a clean quartz substrate was then slowly and vertically lowered to the surface of the monolayer, bringing it into contact with the monolayer. The substrate was then slowly lifted, transferring the monolayer onto it. By repeating the steps as the monolayer surface dries, multilayered ordered BSO NWs films (order-BSO) can be obtained through layer-by-layer accumulation, and N layers can be obtained by repeating the transfer N times. Chiral BSO NWs films are obtained by changing the stacking angle between layers. Left-handed (LH-BSO) and right-handed (RH-BSO) films are obtained by rotating the quartz substrate clockwise or counterclockwise by a certain angle and then transferring the next layer onto the surface of the previous layer. For disordered BSO NWs membranes, they are prepared by dropping BSO NWs onto any point on a square water surface without compression.
[0025] like Figure 4 and Figure 5 As shown, chiral BSO NWs membranes with different numbers of layers (1+1, 2+2, 3+3, 4+4) and different angles (30°, 45°, 60°) were prepared, exhibiting significant CD absorption.
[0026] Example 4 This embodiment prepared a chiral BCSO NWs thin film, and the specific steps are as follows: The dried BCSO20 NWs, BCSO30 NWs, and BCSO40 NWs obtained in Example 2 were redispersed in a mixed solution of n-hexane and ethanol (volume ratio 1:1) to obtain a final concentration of 5 mg / mL. The BCSO NWs solution was injected onto a square water surface using a syringe, and a monolayer was formed after solvent evaporation. The surface monolayer was then slowly compressed to increase the surface molecular density, and a clean quartz substrate was then slowly and vertically lowered to the surface of the monolayer, bringing it into contact with the monolayer. The substrate was then slowly lifted, transferring the monolayer onto it. By repeating the steps while the monolayer surface dries, multilayer ordered BCSO films can be obtained through layer-by-layer accumulation, and N layers can be obtained by repeating the transfer N times. Chiral BSO NWs films were obtained by changing the stacking angle between layers (all angles were 45°). Left-handed (LH-BCSO) and right-handed (RH-BCSO) films were obtained by rotating the quartz substrate clockwise or counterclockwise by a certain angle and then transferring the next layer onto the surface of the previous layer. For disordered BCSO NWs membranes, BCSO NWs are prepared by dropping BCSO NWs onto any point on a square water surface without compression.
[0027] like Figure 6 As shown, the films constructed with BCSO30 NWs exhibit higher CD signals under different doping ratios, while the films constructed with BCSO20 NWs and BCSO40 NWs show weaker chiral strength.
[0028] Example 5 This embodiment is used to investigate the piezoelectric hydrogen evolution rate of membranes constructed with different sorting methods of BSO NWs. The specific operation method is as follows: In the piezoelectric hydrogen evolution experiment, pre-prepared membrane catalysts, including disordered BSO, ordered BSO, left-chirm BSO (LH-BSO), and right-chirm BSO (RH-BSO), were used. Each prepared membrane was placed in a gas-tight glass bottle along with 9 mL of deionized water and 1 mL of methanol. The apparatus was purged with nitrogen for 10 minutes to completely eliminate air from the system. Then, ultrasound was started and timed. Gas samples were extracted from the bottles using a syringe after 0, 5, 10, 20, and 30 minutes of ultrasonic treatment and immediately injected into a gas chromatograph for quantitative analysis of hydrogen content.
[0029] Depend on Figure 7 It can be seen that the hydrogen evolution activity of the four membranes is ranked as follows: LH-BSO≈RH-BSO>order-BSO>disorder-BSO.
[0030] Example 6 This embodiment is used to investigate the piezoelectric-photosynergistic hydrogen evolution rate of chiral BSO NWs under different illuminations. The specific operation method is as follows: In the piezoelectric-photocatalyzed hydrogen evolution experiment, pre-prepared membrane catalysts, including a left-handed membrane (LH-BSO) and a right-handed membrane (RH-BSO), were used. The prepared membranes were placed in airtight glass vials along with 9 mL of deionized water and 1 mL of methanol, respectively. The apparatus was purged with nitrogen for 10 minutes to completely eliminate air from the system. Then, ultrasonic and photocatalytic treatments (including LP, LCP, and RCP) were initiated and timed. Gas samples were extracted from the vials using a syringe after ultrasonic treatment for 0, 5, 10, 20, and 30 minutes, and immediately injected into a gas chromatograph for quantitative analysis of hydrogen content.
[0031] Depend on Figure 8 It can be seen that under the synergistic effect of ultrasound and light, both LH-BSO NWs membranes and RH-BSO NWs membranes exhibit higher hydrogen evolution activity than the single piezoelectric catalytic system. Furthermore, the hydrogen evolution activity of LH-BSO NWs membranes under LCP irradiation is higher than that under RCP irradiation, while RH-BSO NWs exhibits the opposite, showing higher catalytic activity under RCP.
[0032] Example 7 This embodiment is used to investigate the piezoelectric hydrogen evolution rate of BCSO NWs films with different proportions of cobalt doping. The specific operation method is as follows: In the piezoelectric hydrogen evolution experiment, ordered membrane catalysts, including order-BCSO20, order-BCSO30, and order-BCSO40 membranes, were prepared in advance. The prepared membranes were placed in airtight glass bottles along with 9 mL of deionized water and 1 mL of methanol, respectively. The apparatus was purged with nitrogen for 10 minutes to completely eliminate air from the system. Then, ultrasound was started and timed. Gas samples were extracted from the bottles using a syringe after 0, 5, 10, 20, and 30 minutes of ultrasonic treatment, and immediately injected into a gas chromatograph for quantitative analysis of hydrogen content.
[0033] Depend on Figure 9 It can be seen that the BCSO30 NWs film exhibits higher catalytic hydrogen evolution activity than the undoped BSO NWs.
[0034] Example 8 This embodiment is used to investigate the piezoelectric hydrogen evolution rate of chiral BCSO30 NWs and the piezoelectric-photosynergistic catalytic hydrogen evolution rate under different illuminations. The specific operation method is as follows: In the piezoelectric-photocatalyzed hydrogen evolution experiment, pre-prepared membrane catalysts, including a left-handed membrane (LH-BCSO30) and a right-handed membrane (RH-BCSO30), were used. The prepared membranes were placed in airtight glass vials along with 9 mL of deionized water and 1 mL of methanol, respectively. The apparatus was purged with nitrogen for 10 minutes to completely eliminate air from the system. Then, ultrasonic and light irradiation (including no light, LP, LCP, and RCP) were initiated and timed. Gas samples were extracted from the vials using a syringe after ultrasonic treatment for 0, 5, 10, 20, and 30 minutes, and immediately injected into a gas chromatograph for quantitative analysis of hydrogen content.
[0035] Depend on Figure 10 It can be seen that, under the synergistic effect of ultrasound and light, both LH-BCSO30 NWs membranes and RH-BCSO30 NWs membranes exhibit higher hydrogen evolution activity than the single piezoelectric catalytic system, and also higher hydrogen evolution rates than the undoped LH-BSO NWs membranes and RH-BSO NWs membranes. Furthermore, the hydrogen evolution activity of LH-BCSO30 NWs membranes under LCP irradiation is higher than that under RCP irradiation, while RH-BCSO30 NWs exhibits the opposite, showing higher catalytic activity under RCP irradiation.
[0036] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A method for preparing bismuth-based nanowires (BSO NWs), characterized in that, Includes the following steps: The sulfur source, bismuth source, and ammonia water are mixed and dissolved in water, heated and reacted, then cooled to separate the solid and liquid phases and washed to obtain the solid phase, which is the bismuth-based nanowire BSO NWs.
2. The preparation method according to claim 1, characterized in that, The sulfur source is selected from sodium sulfate and / or potassium sulfate; The bismuth source is selected from bismuth nitrate and / or bismuth chloride; The molar ratio of the sulfur source to the bismuth source is 1:3 to 3:1; The heating reaction is carried out at a temperature of 150-220℃ for a time of 12-36 h.
3. A bismuth-based nanowire (BSO) NWs, characterized in that, The sample prepared by the method described in claim 1 or 2 has a bismuth defect shell on its surface.
4. A cobalt-doped bismuth-based nanowire BCSO NWs, characterized in that, The bismuth-based nanowires (BSO NWs) according to claim 3 are bulk-doped with cobalt.
5. The method for preparing cobalt-doped bismuth-based nanowires according to claim 4, characterized in that, Includes the following steps: The sulfur source, bismuth source, cobalt source and ammonia water are mixed and dissolved in water, heated and reacted, cooled and separated into solid and liquid phases, and washed to obtain the solid phase, which is the bismuth-based nanowire BSO NWs.
6. The preparation method according to claim 5, characterized in that, The sulfur source is selected from sodium sulfate and / or potassium sulfate; The bismuth source is selected from bismuth nitrate and / or bismuth chloride; The cobalt source is selected from cobalt chloride and / or cobalt nitrate; The molar ratio of the cobalt source to the bismuth source is 1:20 to 1:40; The molar ratio of the sulfur source to the bismuth source is 1:3 to 3:1; The heating reaction is carried out at a temperature of 150-220℃ for a time of 12-36 hours.
7. A chiral BSO NWs thin film, characterized in that, The method for preparing the chiral BSO NWs thin film includes the following steps: A bismuth-based nanowire BSO NWs solution is provided; A bismuth-based nanowire (BSO) NWs solution was injected onto a water surface, and after the solvent evaporated, it was compressed to form a monolayer film; the monolayer film was then transferred to the surface of a substrate. When the surface of a single-layer film is dry, N layers of film are obtained by repeating the transfer N times; and chiral BSO NWs films are obtained by changing the stacking angle θ between the layers.
8. The preparation method according to claim 7, wherein the concentration of the bismuth-based nanowire (BSO) NWs solution is 1-20 mg / mL; The stacking angle θ ranges from 0 to 60°.
9. A chiral BCSO NWs thin film, characterized in that, Includes the following steps: The method for preparing the chiral BCSO NWs thin film includes the following steps: A bismuth-based nanowire BCSO NWs solution is provided; A bismuth-based nanowire (BSO) NWs solution was injected onto a water surface, and after the solvent evaporated, it was compressed to form a monolayer film; the monolayer film was then transferred to the surface of a substrate. When the surface of the monolayer film is dry, N layers of film are obtained by repeating the transfer N times; and chiral BCSO NWs film is obtained by changing the stacking angle θ between the layers.
10. The application of the chiral BSO NWs thin film of claim 7 or the chiral BCSO NWs thin film of claim 8 in piezoelectric-photocatalytic synergistic hydrogen evolution.