Antimony-doped bismuth nanosheet, preparation method thereof and electrochemical sensor

Abstract

The invention discloses an antimony-doped bismuth nanosheet, a preparation method thereof and an electrochemical sensor, and belongs to the technical field of electrochemical sensing. The composition of the antimony doped bismuth nanosheet is expressed as xSb-Bi NS, wherein x is 1%-5% and represents the doping proportion of Sb. The antimony-doped bismuth nanosheet has higher structural stability and electro-catalytic performance, and when the antimony-doped bismuth nanosheet is used for modifying a working electrode of an electrochemical sensor, the electrochemical sensor has high sensitivity, high selectivity, high stability and low detection limit when multiple metal ions such as Zn (II), Cd (II) and Pb (II) are detected at the same time.

Description

Technical Field

[0001] This invention relates to the field of electrochemical sensing technology, and in particular to an antimony-doped bismuth nanosheet, its preparation method, and an electrochemical sensor. Background Technology

[0002] Heavy metal ion pollution in water bodies has become a widespread environmental problem globally. Among them, Zn(II), Cd(II), and Pb(II) ions exhibit bioaccumulation and toxicity, and long-term intake can cause serious harm to ecosystems and human health. Therefore, developing analytical technologies capable of highly sensitive, rapid, and simultaneous detection of multiple heavy metal ions in complex aquatic environments is a crucial task urgently needing to be addressed in the fields of environmental monitoring and public safety.

[0003] Existing methods for heavy metal ion detection mainly include atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, and ultraviolet-visible spectroscopy. While these methods offer high detection sensitivity, they typically require expensive, large-scale equipment, complex sample pretreatment procedures, and specialized personnel, making them unsuitable for rapid on-site detection and continuous industrial monitoring. Therefore, in recent years, electrochemical sensing technology has attracted significant attention due to its portable equipment, ease of operation, low cost, and ability to enable rapid on-site detection.

[0004] In the prior art, CN116726908A discloses an electrochemical sensor electrode for simultaneous detection of lead and cadmium ions, its preparation method, and its application. This invention synthesizes bismuth-doped bismuth tungstate (Bi / Bi2WO6) material with a multi-petal-shaped micro-protrusion structure via a hydrothermal method, and loads it onto the surface of a glassy carbon electrode using a drop-coating method to construct the sensor's working electrode interface, achieving simultaneous detection of cadmium and lead ions in aqueous solution and realizing the square-wave anodic stripping voltammetry detection of lead and cadmium ions. CN112792350A discloses antimony and / or bismuth nanosheets, antimonene and / or bismuthene, and their preparation methods. This invention utilizes a eutectic salt system, group VA metals, and aluminum powder (Al) as reaction raw materials to prepare metal nanosheets. The thickness of the antimony and / or bismuth nanosheets ranges from 10 to 100 nm; the thickness of the antimonene or bismuthene materials ranges from 0.5 to 1.5 nm. The method has the advantages of high yield, low cost, high efficiency and easy scale-up preparation, but it is not recorded that the material can improve electrocatalytic performance or be applied to the simultaneous rapid detection of multiple heavy metal ions.

[0005] Although electrochemical heavy metal detection technology based on bismuth-based materials has a certain research foundation, many shortcomings remain. First, traditional pure bismuth nanosheets and bismuth film electrodes have poor oxidation resistance, easily forming surface oxide layers in air and electrolyte environments, resulting in poor structural stability and subsequent electrode activity decay, leading to signal drift and poor long-term stability. Second, pure bismuth materials have limited electrocatalytic capabilities. In multi-metal ion coexistence systems, their adsorption and deposition abilities for Zn(II), Cd(II), and Pb(II) are weak, and signal peaks easily overlap, resulting in low detection resolution and selectivity. Especially for Zn(II), traditional bismuth electrodes struggle to achieve stable and sensitive electrochemical stripping signals, often resulting in low detection sensitivity, inaccuracy, or even failure to detect. Simultaneously, due to the uneven number of layers and small specific surface area of ​​traditional materials, there are insufficient effective active sites, leading to low electrode reaction rates and insufficient electron transfer efficiency, making it difficult to significantly reduce the detection limit. Furthermore, significant inter-ion interference in complex water samples limits the long-term stability and industrial-scale application of the sensing system. The aforementioned problems severely restrict the development of electrochemical detection technology for multiple metal ions towards high performance, broad applicability, and engineering feasibility.

[0006] Therefore, it is urgent to research and develop a high-performance electrochemical sensor system that can be used for actual water sample monitoring, and to provide a reliable and scalable new technical solution for industrial wastewater monitoring, environmental detection and the development of commercial sensors. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide an antimony-doped bismuth nanosheet, its preparation method, and an electrochemical sensor. The antimony-doped bismuth nanosheet exhibits higher structural stability and electrocatalytic performance.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] This invention provides an antimony-doped bismuth nanosheet, the composition of which is represented as xSb-Bi NS;

[0010] Where x is 1%-5%, representing the doping ratio of Sb.

[0011] The x is preferably 3%-5%; more preferably 3%.

[0012] In some specific embodiments of the present invention, the composition of the antimony-doped bismuth nanosheets is expressed as 1%Sb-Bi. NS, 3% Sb-Bi NS or 5%Sb-Bi NS.

[0013] Preferably, the antimony-doped bismuth nanosheets of the present invention have a sheet-like structure with an average diameter of 103.24 ± 20 nm and an average thickness of 5.34 ± 1.47 nm.

[0014] In the antimony-doped bismuth nanosheets of the present invention, antimony (Sb) is uniformly dispersed in the nanosheets.

[0015] The antimony-doped bismuth nanosheets of the present invention significantly improve the specific surface area, number of active sites and interfacial electron transport capability due to the doping of antimony (Sb), and effectively suppress the surface oxidation of bismuth materials, thereby greatly enhancing the stability and durability of the materials.

[0016] The antimony-doped bismuth nanosheets described in this invention exhibit good structural stability and excellent electrocatalytic performance.

[0017] This invention also provides a method for preparing the above-mentioned antimony-doped bismuth nanosheets, comprising the following steps:

[0018] (1) A precursor solution is obtained by mixing a soluble antimony salt, a soluble bismuth salt, and a solvent and heating the mixture.

[0019] (2) The precursor solution and the reducing agent are mixed and reacted to obtain the antimony-doped bismuth nanosheets.

[0020] This invention achieves precise control over the amount of antimony doping and the morphology of the antimony-doped bismuth nanosheets through a simple chemical reduction method.

[0021] Preferably, the heating temperature in step (1) of this invention is 80℃-180℃; more preferably 110℃-130℃; and even more preferably 120℃.

[0022] The present invention does not impose any special limitation on the heating device; any device known to those skilled in the art is acceptable.

[0023] In some specific embodiments of the present invention, an oil bath is preferred.

[0024] Preferably, the ratio of antimony content in the soluble antimony salt to bismuth content in the soluble bismuth salt is (0.01-0.2):1; more preferably, it is (0.01-0.1):1.

[0025] Preferably, the soluble antimony salt is selected from one or more of antimony trichloride, antimony acetate, antimony nitrate, antimony sulfate, and antimony bromide; more preferably, it is antimony trichloride.

[0026] Preferably, the soluble bismuth salt is selected from one or more of bismuth trichloride, bismuth nitrate, bismuth acetate, bismuth subsalicylate, bismuth iodide, bismuth bromide, bismuth citrate, bismuth sulfate, and bismuth perchlorate; more preferably, it is bismuth trichloride or bismuth nitrate.

[0027] Preferably, the solvent is selected from one or more of water, ethanol, 2-ethoxyethanol, methanol, isopropanol, oleic acid, oleylamine, diphenyl ether, ethylene glycol, glycerol, N,N-dimethylformamide, and dimethyl sulfoxide; more preferably, it is 2-ethoxyethanol.

[0028] Preferably, the reducing agent is selected from one or more of sodium borohydride, hydrazine hydrate, ascorbic acid, and citric acid; more preferably, it is sodium borohydride.

[0029] After obtaining the precursor solution described in step (1), the present invention cools it to room temperature and then adds a reducing agent.

[0030] Preferably, steps (1) and (2) of the present invention are carried out under an inert atmosphere.

[0031] The inert atmosphere includes, but is not limited to, nitrogen, argon, etc.

[0032] In some specific embodiments of the present invention, nitrogen is preferred.

[0033] After the mixing reaction in step (2) of the above preparation method is completed, post-treatments such as washing, centrifugation, and drying are also included.

[0034] The present invention does not specifically limit the solvent used for washing, and any solvent well known to those skilled in the art is acceptable.

[0035] In some specific embodiments of the present invention, the solvent for washing is preferably ethanol.

[0036] The above preparation method is simple and efficient, suitable for industrial-scale production, and can significantly reduce the batch variation of the antimony-doped bismuth nanosheets. This enables the electrochemical sensor with the antimony-doped bismuth nanosheets-modified working electrode to maintain high stability and excellent reproducibility during long-term storage and continuous testing.

[0037] The present invention also provides an electrochemical sensor, comprising a working electrode modified with antimony-doped bismuth nanosheets;

[0038] The antimony-doped bismuth nanosheets are the antimony-doped bismuth nanosheets described above or the antimony-doped bismuth nanosheets prepared by the above preparation method.

[0039] This invention fundamentally improves the antioxidant properties, electrochemical activity, and repeatability of the working electrode by modifying it with antimony-doped bismuth nanosheets, significantly reduces signal interference caused by the coexistence of multiple ions, and achieves high selectivity, long-term stability, and low detection limit for simultaneous and trace detection of multiple metal ions in complex water samples.

[0040] Preferably, the modification is performed on the surface of the working electrode by coating, chemical bonding or electrochemical deposition.

[0041] The coating can be applied by drop or spin coating.

[0042] Preferably, the working electrode is selected from a metal electrode, a glassy carbon electrode, or an ITO electrode.

[0043] The metal electrode is preferably Au, Ag, or Pt.

[0044] The aforementioned electrochemical sensor is a three-electrode system, which also includes a reference electrode and a counter electrode.

[0045] The reference electrode is preferably a silver / silver chloride electrode or a calomel electrode.

[0046] The counter electrode is preferably a platinum wire electrode.

[0047] When the electrochemical sensor described in this invention is used for the simultaneous electrochemical detection of Zn(II), Cd(II), and Pb(II) in water, it exhibits high selectivity, high sensitivity, ultra-low detection limit, and long-term stability. This effectively solves the problems of insufficient sensitivity, poor resolution, weak antioxidant properties, and poor batch stability of existing electrochemical sensors in the simultaneous detection of multiple metal ions.

[0048] The electrochemical sensor was used for the simultaneous high-sensitivity detection of heavy ions (lead, cadmium, and zinc) using methods such as DPV, square wave voltammetry, or cyclic voltammetry. The linear range of the electrochemical sensor is two concentration ranges: 0.001-1 µM and 1.2-12 µM. Simultaneously, the detection limits are 0.137 nM for lead ions, 0.140 nM for cadmium ions, and 0.114 nM for zinc ions. Furthermore, the electrochemical sensor exhibits good reproducibility, stability, and anti-interference capabilities for the detection of these three ions.

[0049] Compared with existing technologies, the composition of the antimony-doped bismuth nanosheets provided by this invention is expressed as xSb-Bi NS; where x is 1%-5%, representing the doping ratio of Sb. The antimony-doped bismuth nanosheets exhibit higher structural stability and electrocatalytic performance. When used to modify the working electrode of an electrochemical sensor, they enable the sensor to simultaneously detect multiple metal ions such as Zn(II), Cd(II), and Pb(II) with high sensitivity, high selectivity, high stability, and low detection limit. Attached Figure Description

[0050] Figure 1 The images show the structural characterization of antimony-doped bismuth nanosheets, where (a)-(c) are transmission electron microscope (TEM) images of the antimony-doped bismuth nanosheets, (d) is an atomic force microscope (AFM) image of the nanosheets, and (e) and (f) are high-resolution TEM images of (c) with scale bars of 10 nm and 2 nm, respectively.

[0051] Figure 2The results of the concentration gradient detection of heavy metal ions in 0.2 M acetic acid buffer solution by an electrochemical sensor based on antimony-doped bismuth nanosheets are shown in the figure. (a) is the square wave anodic dissolution voltammetric current response curve of the three ions, (b) is the linear fitting curve of the curve in the concentration range of 0.001 - 1 µM, and (c) is the linear fitting curve of the curve in the concentration range of 1.2 - 12 µM.

[0052] Figure 3 The graphs show the reproducibility, stability, and anti-interference performance of the electrochemical sensor for ion detection. (a) shows the current response of the electrochemical sensor in the presence of common interfering ions, (b) shows the reproducibility of different electrodes, (c) shows the reproducibility of the electrochemical sensor, and (d) shows the stability of the electrochemical sensor.

[0053] Figure 4 The figures show a comparative study of the electrochemical responses of electrochemical sensors with different modified electrodes to ion detection under the same experimental conditions. (a) is the voltammetric current response curve of the square wave anodic stripping of three ions by different modified electrodes, and (b) is a statistical comparison of the peak current of the oxidation peak of the three ions by different electrodes. Detailed Implementation

[0054] To further illustrate the present invention, the following detailed description of the antimony-doped bismuth nanosheets, their preparation method, and the electrochemical sensor provided by the present invention is provided in conjunction with embodiments.

[0055] Example 1

[0056] (I) Preparation of antimony-doped bismuth nanosheets

[0057] 94.6 mg of bismuth trichloride and 2.8 mg of antimony trichloride were dissolved in 10 mL of 2-ethoxyethanol and sonicated to form a homogeneous solution. The solution was placed in a three-necked round-bottom flask, heated to 120°C, and stirred under nitrogen atmosphere for 30 minutes. After the reaction system cooled naturally to room temperature, 2 mL of 3 mM sodium borohydride aqueous solution was added, and stirring was continued for 10 minutes under nitrogen atmosphere. The resulting black precipitate was washed three times with ethanol, centrifuged at 1000 rpm for 3 minutes each time, finally obtaining antimony-doped bismuth nanosheets.

[0058] Figure 1The images show the structural characterization of antimony-doped bismuth nanosheets. (a)-(c) are transmission electron microscopy (TEM) images of the antimony-doped bismuth nanosheets. (a) and (b) show that the obtained nanosheets exhibit a sheet-like structure with an average diameter of 103.24 ± 20 nm, and the nanosheets show a random orientation distribution. (d) is an atomic force microscopy (AFM) image of the nanosheets, demonstrating that the nanosheet thickness is only 5.34 ± 1.47 nm. (e) and (f) are high-resolution TEM images of the nanosheets in (c) with scale bars of 10 nm and 2 nm, respectively. In (e), the red boundary indicates a curved grain boundary, demonstrating a high-exponential step structure. The 0.327 nm lattice fringes in (f) belong to the bismuth (012) crystal plane, confirming the formation of the antimony-bismuth alloy. (g)-(j) are elemental distribution maps of the antimony-doped bismuth nanosheets. These elemental maps not only confirm the successful incorporation of antimony into the bismuth nanosheets but also show that the dopant element is uniformly distributed within the nanosheets, and no other impurities were detected.

[0059] The chemical composition of the antimony-doped bismuth nanosheets prepared above was analyzed by ICP-AES. The results showed that the antimony doping content (content) in the antimony-doped bismuth nanosheets was 3.43 wt%, and the bismuth content was 96.57 wt%, expressed as 3% Sb-Bi. NS.

[0060] (II) Preparation of working electrode modified with antimony-doped bismuth nanosheets

[0061] A 5 mm diameter glassy carbon electrode was used as the working electrode. This electrode was polished sequentially with 1 µm and 0.05 µm alumina powders until a mirror-like finish was achieved, followed by rinsing with ultrapure water. Nanosheets were dispersed in a binder solution consisting of 75% water, 24% ethanol, and 1% Nafion solution (5% by mass) to prepare a nanosheet suspension with a concentration of 1 mg / mL. Approximately 5 µL of the suspension was drop-coated onto the defined area of ​​the glassy carbon electrode and allowed to cure at room temperature for 1 hour.

[0062] (III) Fabrication of Electrochemical Sensors

[0063] An electrochemical sensor was prepared by using the glassy carbon electrode modified with nanosheets obtained in step (ii) as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum sheet as the counter electrode.

[0064] (iv) Performance Testing

[0065] The electrochemical sensor prepared in (III) was used to detect heavy metal ions (Zn(II), Cd(II), Pb(II)) at concentrations ranging from 0.001 μM to 12 μM in 0.2 M acetic acid buffer solution (pH=4) using square wave anodic stripping voltammetry. A significant increase in peak current intensity was observed with increasing ion concentration. Subsequent data processing yielded a curve showing the relationship between peak current intensity and ion concentration, enabling continuous analysis of the three ions (e.g., ...). Figure 2 (As shown).

[0066] Figure 2 This paper presents the detection of heavy metal ions in a 0.2 M acetic acid buffer solution using an electrochemical sensor based on antimony-doped bismuth nanosheets (the electrochemical sensor prepared in step (iii)). (a) shows the square-wave anodic stripping voltammetric current response curves for the three ions, demonstrating the sensor's excellent simultaneous detection capability. (b) shows the linear fitting graph of the curves in the 0.001-1 µM concentration range of (a). Simultaneous detection of zinc ions (Zn(II)), cadmium ions (Cd(II)), and lead ions (Pb(II)) in the low concentration range shows sensitivities of 3.09 µA / µM, 2.67 µA / µM, and 4.12 µA / µM, respectively, proving the excellent trace detection capability of the sensor described in this invention. (c) shows the linear fitting graph of the curves in the 1.2-12 µM concentration range of (a). The simultaneous detection of zinc (Zn(II)), cadmium (Cd(II)), and lead (Pb(II)) ions in the high-concentration region showed sensitivities of 6.10 µA / µM, 9.90 µA / µM, and 15.65 µA / µM, respectively, demonstrating that the sensor maintains excellent conductivity and active site utilization over a wide linear range. Based on the above test results, the detection limits of this electrochemical sensor for Zn(II), Cd(II), and Pb(II) were calculated to be 0.114 nM, 0.140 nM, and 0.137 nM, respectively, exhibiting excellent detection performance.

[0067] Furthermore, this electrochemical sensor exhibits good reproducibility, stability, and anti-interference capabilities for the detection of three ions. Anti-interference studies showed that the effects of potential interfering ions such as Ca(II), Fe(III), Mn(II), Mg(II), Ni(II), and Co(II) on simultaneous detection were investigated at a concentration level of 12 μM in an acetic acid buffer solution at pH 4.0. According to statistical standards, a relative standard deviation ≤ ±5% caused by interfering ions was considered to indicate no interference.

[0068] Figure 3The graphs show the reproducibility, stability, and anti-interference capabilities of the electrochemical sensor for ion detection. (a) shows the current response of the electrochemical sensor in the presence of common interfering ions, indicating that the signal changes caused by each interfering ion are negligible (calculated standard deviation <3%), confirming the sensor's excellent anti-interference ability. (b) shows the reproducibility test results for different electrodes. The reproducibility assessment shows that four electrochemical sensors were prepared using the same incubation process and tested in a pH 4.0 acetic acid buffer solution containing 12 μM Zn(II) / Cd(II) / Pb(II). Triple parallel measurements (n=3) showed that the relative standard deviations for the detection of the three heavy metal ions by the four electrodes were 3.0% (Zn(II)), 1.73% (Cd(II)), and 2.04% (Pb(II)), respectively, indicating good reproducibility of the preparation process. Repeatability testing showed that the same sensor was used to detect a 12 μM mixed heavy metal solution six times consecutively at an enrichment potential of -1.7 V, with the electrode thoroughly cleaned after each measurement. (c) shows the reproducibility test results of the electrochemical sensor. The relative standard deviations of the six measurements (n=6) were 1.52% (Zn(II)), 1.65% (Cd(II)), and 2.23% (Pb(II)), demonstrating the sensor's excellent repeatability. (d) shows the stability test results of the electrochemical sensor. Stability analysis revealed that after 21 days of continuous monitoring of the same sensor, the sensor's response signals to Zn(II), Cd(II), and Pb(II) maintained 95.7%, 96.2%, and 91.5% of their initial values, respectively. This result indicates that the sensor exhibits only minor signal attenuation within three weeks, demonstrating its long-term potential for application in environmental monitoring.

[0069] Example 2

[0070] Similar to Example 1, the difference lies in the amount of antimony trichloride used in step (a) of preparing antimony-doped bismuth nanosheets. In this example, it is 0.9 mg, resulting in an antimony doping content (content) of 1 wt% in the prepared antimony-doped bismuth nanosheets, expressed as 1% Sb-Bi. NS.

[0071] Example 3

[0072] Similar to Example 1, the difference lies in the amount of antimony trichloride used in step (i) of preparing antimony-doped bismuth nanosheets. In this example, it is 4.7 mg, resulting in an antimony doping content (content) of 5 wt% in the prepared antimony-doped bismuth nanosheets, expressed as 5% Sb-Bi. Figure 4 shows a comparison of the electrochemical responses of GCE (bare glassy carbon electrode), Bi nanosheets (pure bismuth nanosheets), and Sb-Bi nanosheets with different doping ratios (1%, 3%, and 5% Sb doping ratios) under the same experimental conditions (12 µM heavy metal ion mixed solution), intuitively and quantitatively confirming the excellent electrocatalytic performance of the material of this invention. Among them, (a) shows the square wave anodic dissolution voltammetric current response curves of different electrodes to the three ions. Among them, the electrodes modified with 1% Sb-Bi NS, 3% Sb-Bi NS, and 5% Sb-Bi NS showed the sharpest and stronger oxidation dissolution peaks compared with the bare glassy carbon electrode and the undoped pure bismuth nanosheet electrode. Moreover, the response signal showed a significant increasing trend as the doping amount increased to 3%. (b) is a statistical chart comparing the peak current values ​​of oxidation peaks of different electrodes to the three ions. The electrode modified with 3% Sb-Bi NS reached the maximum value for the oxidation peak current response to Zn(II), Cd(II), and Pb(II), which was significantly better than other comparative groups. This significant signal enhancement is attributed to the introduction of high-valence Sb(V) states into the lattice by appropriate antimony doping, which effectively increases the number of surface active sites and significantly accelerates the electron transport dynamics at the electrode interface, thus directly demonstrating that the material possesses higher sensitivity and superior electrocatalytic activity.

[0073] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An antimony-doped bismuth nanosheet, characterized in that, The composition is represented as xSb-Bi NS; Wherein, x is 1%-5%, representing the doping ratio of Sb.

2. The antimony-doped bismuth nanosheets according to claim 1, wherein, The antimony-doped bismuth nanosheet has a lamellar structure, with an average diameter of 103.24 ± 20 nm and an average thickness of 5.34 ± 1.47 nm.

3. The method of producing antimony-doped bismuth nanosheets according to claim 1 or 2, characterized by, The method comprises the following steps: (1) mixing a soluble antimony salt, a soluble bismuth salt and a solvent, and then heating to obtain a precursor solution; (2) mixing the precursor solution and a reducing agent to obtain the antimony-doped bismuth nanosheet.

4. The production method according to claim 3, characterized by, The heating temperature in step (1) is 80-180°C.

5. The preparation method according to claim 3, characterized in that, The content ratio of antimony in the soluble antimony salt to bismuth in the soluble bismuth salt is (0.01-0.2):

1.

6. The preparation method according to claim 3, characterized in that, The soluble antimony salt is selected from one or more of antimony trichloride, antimony acetate, antimony nitrate, antimony sulfate, antimony bromide; The soluble bismuth salt is selected from one or more of bismuth trichloride, bismuth nitrate, bismuth acetate, bismuth subsalicylate, bismuth iodide, bismuth bromide, bismuth citrate, bismuth sulfate, bismuth perchlorate; The solvent is selected from one or more of water, ethanol, 2-ethoxyethanol, methanol, isopropanol, oleic acid, oleylamine, diphenyl ether, ethylene glycol, glycerol, N,N-dimethylformamide, dimethyl sulfoxide.

7. The preparation method according to claim 3, characterized in that, The reducing agent is selected from one or more of sodium borohydride, hydrazine hydrate, ascorbic acid, citric acid.

8. The preparation method according to claim 3, characterized in that, Both steps (1) and (2) are carried out under an inert atmosphere.

9. An electrochemical sensor, characterized in that The working electrode modified with the antimony-doped bismuth nanosheet; The antimony-doped bismuth nanosheet is the antimony-doped bismuth nanosheet of claim 1 or 2, or prepared by the method of any one of claims 3-8.

10. The electrochemical sensor of claim 9, wherein, The modification is achieved by coating, chemical bonding or electrochemical deposition on the surface of the working electrode; The working electrode is selected from a metal electrode, a glassy carbon electrode or an ITO electrode.

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