Black phosphorus field-effect tube lead ion detector and use method thereof

Abstract

The invention belongs to the technical field of lead ion detection, and particularly relates to a black phosphorus field-effect tube lead ion detector and a use method thereof. The detector comprises an insulating substrate, a gate electrode layer, a gate electrode insulating layer, a sensitive layer, a source electrode and a drain electrode. The gate electrode layer is arranged on the insulating substrate, and the sensitive layer is arranged on the gate electrode insulating layer; particularly, the sensitive layer comprises a black phosphorus material, and noble metal particles are arranged on the surface of the sensitive layer. According to the invention, black phosphorus is used as a sensitive material of the field effect transistor, the black phosphorus and lead ions have good chemical matching property, and a stable coordination effect is formed through surface phosphorus atoms and lead ions, so that the conductivity of a channel is obviously changed; in addition, precious metal particles are introduced to the surface of the black phosphorus sensitive layer, so that the selective adsorption capacity of lead ions is enhanced. In a word, high-selectivity and high-sensitivity electrical detection of lead ions can be realized, and a high-performance field-effect tube sensor platform is provided for rapid monitoring of heavy metal pollutants.

Description

Technical Field

[0001] The present invention belongs to the technical field of lead ion detection, and in particular relates to a black phosphorus field effect tube lead ion detector and a method for using the same. Background Art

[0002] Lead is a typical heavy metal environmental pollutant with high toxicity and bioaccumulation. It is widely present in the wastewater, waste gas and waste residue discharged from industrial processes such as mineral smelting, battery manufacturing, paint and coating, and electronic waste treatment. 2+ ) Once it enters the water or soil environment, it can easily enter the human body through drinking water, food chain or respiratory pathway, accumulate in the body and damage the functions of multiple organ systems.

[0003] Research has shown that lead ions pose significant risks to the nervous, hematopoietic, urinary, and immune systems. They can cause irreversible neurodevelopmental damage in children, leading to reduced learning ability, attention deficit, and intellectual disability. Long-term exposure to trace amounts of lead ions in adults can also lead to chronic conditions such as anemia, kidney damage, and hypertension. Therefore, highly sensitive and rapid lead ion detection is crucial in environmental monitoring, drinking water safety, food inspection, and public health.

[0004] Currently, commonly used lead ion detection technologies include atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry (ICP-MS), anodic stripping voltammetry (ASV), and colorimetry. These methods have a certain degree of accuracy, but are generally expensive, complex, time-consuming, and require a high degree of expertise. Furthermore, they are unsuitable for real-time online monitoring or portable applications, and struggle to meet the demands for low-concentration, on-site, and rapid detection.

[0005] In recent years, field-effect transistor (FET)-based sensor technology has garnered widespread attention for metal ion detection. The FET structure exhibits three-terminal control characteristics, and its channel conductance is highly sensitive to changes in surface carrier density. When target ions adsorb on the surface of the sensitive layer, this significantly alters the channel conductivity, leading to an electrical signal output. Compared to traditional methods, FET sensors offer significant advantages, including high sensitivity, fast response, miniaturization, low power consumption, and ease of integration.

[0006] In FET sensors, the performance of the sensitive material has a decisive influence on detection sensitivity and selectivity. Existing studies have attempted to use two-dimensional or nanostructured materials such as graphene, MoS2, carbon nanotubes, and metal oxide nanomaterials as the sensitive layer of FETs. However, these materials still suffer from weak response signals, poor selectivity, high detection limits, and low repeatability when used for lead ion detection, making them difficult to meet the application requirements of highly sensitive trace lead ion detection.

[0007] Therefore, how to construct a new detector based on FET structure and with high-performance sensitive materials as the core, which can achieve low-concentration, high-selectivity and fast-response detection of lead ions, has become a technical problem that needs to be solved urgently. Summary of the Invention

[0008] To solve the above problems, the present invention provides a black phosphorus field-effect transistor lead ion detector, which includes an insulating substrate, a gate electrode layer, a gate electrode insulating layer, a sensitive layer, a source electrode, and a drain electrode; the gate electrode layer is arranged on the insulating substrate, and the sensitive layer is arranged on the gate electrode insulating layer; in particular, the sensitive layer includes black phosphorus material, and precious metal particles are provided on the surface of the sensitive layer.

[0009] In the present invention, black phosphorus is selected as the core material of the sensitive layer. Black phosphorus has a unique layered structure and abundant lone pairs of electrons, and black phosphorus has good chemical compatibility with lead ions. The phosphorus atoms on the surface of black phosphorus have high electrophilicity and can form a stable coordination effect with lead ions. This not only ensures the efficient adsorption of lead ions, but also can induce perturbations in the black phosphorus band structure, thereby significantly changing the concentration distribution of its channel carriers, and thus causing a significant change in the source-drain current. Compared with other two-dimensional materials, black phosphorus has stronger selectivity and conductivity response to lead ions, and is particularly suitable for sensitive detection of trace metal ions. On this basis, noble metal particles are introduced on the surface of the black phosphorus sensitive layer. On the one hand, the adsorption capacity for lead ions is significantly improved, because the noble metal surface has a natural affinity for lead ions and can serve as an adsorption site to promote the enrichment of lead ions; on the other hand, gold nanoparticles can participate in electronic coupling at the interface with black phosphorus, amplifying the charge redistribution effect induced by lead ion adsorption, thereby enhancing the response intensity of the black phosphorus channel to the presence of lead ions. Ultimately, the present invention can achieve highly selective and highly sensitive electrical detection of lead ions, providing a high-performance field-effect transistor sensor platform for rapid monitoring of heavy metal pollutants.

[0010] Furthermore, the sensitive layer is a single layer or a few layers of black phosphorus sheet, and the thickness of the sensitive layer is 1-10nm. On the one hand, ultra-thin black phosphorus has a larger specific surface area and higher surface activity. Almost all of its atoms are exposed to the external environment, making it easier for lead ions to contact and form coordination bonds with the phosphorus atoms on its surface; on the other hand, the thinner black phosphorus channel is more sensitive to surface charge perturbations. The adsorption of a small amount of lead ions can cause significant changes in carrier concentration or migration behavior, thereby producing an amplification effect on conductivity. In addition, the thin layer structure is also conducive to the rapid regulation of carriers in the vertical direction, improving the response speed of electrical signals.

[0011] Furthermore, the precious metal particles are gold nanoparticles with a particle size of 2-50 nm. Gold nanoparticles have excellent lead affinity, and their surfaces provide a large number of highly active adsorption sites, which facilitate the efficient capture of lead ions. When the particle size is at the nanoscale, gold particles exhibit significant surface plasmon resonance and electron coupling, which can enhance the charge perturbation amplitude in the local electric field after lead ion adsorption, thereby amplifying the conductivity change of the black phosphorus channel.

[0012] Furthermore, the sensitive layer is strip-shaped, running along the direction of the source and drain electrodes. On the one hand, the strip-shaped structure increases the edge ratio of the black phosphorus sensitive layer, providing more highly active boundary sites compared to a continuous film structure, enhancing the adsorption efficiency of lead ions. On the other hand, the spacing between the strips concentrates the current flow in a narrow area. When lead ions adsorb on the strip-shaped channel, the local charge perturbation will have a more significant modulation effect on the overall current, thereby amplifying the output signal.

[0013] Furthermore, titanium dioxide nanoparticles with a particle size of 5-10 nm are distributed on the surface of the sensitive layer. The surface of the titanium dioxide nanoparticles is rich in active functional groups such as hydroxyl groups, which form hydrogen bonds or electrostatic adsorption with lead ions, providing additional enrichment sites and improving the capture efficiency of lead ions. Furthermore, titanium dioxide, as a wide-bandgap semiconductor, can participate in the electron transfer process at the nanoscale, forming a synergistic sensing interface with the black phosphorus channel, making the charge perturbation induced by lead ion adsorption more significant, thereby amplifying the conductivity change signal.

[0014] Furthermore, the precious metal particles have a gold / titanium dioxide core-shell structure, with gold as the core and titanium dioxide as the shell, achieving a synergistic enhancement in lead ion detection sensitivity. On the one hand, the gold core has excellent conductivity and surface plasmon effect, which can efficiently adsorb lead ions and transfer electrons with them, providing strong local charge perturbations to the black phosphorus channel. On the other hand, the titanium dioxide shell is rich in active sites such as hydroxyl groups on its surface, which can further enhance the lead ion capture ability. At the same time, as a semiconductor material, it forms a heterojunction structure with the gold core, creating a built-in electric field, which helps guide electron migration from the titanium dioxide to the gold core, thereby more effectively modulating the black phosphorus channel conductance.

[0015] On the other hand, the present invention also provides a method for using a black phosphorus field effect tube lead ion detector, comprising the following steps: Step 1: Place the solution to be tested on the sensitive layer; Step 2: After the lead ion adsorption is completed, the source-drain current change is tested to determine the lead ion concentration in the solution.

[0016] In step 1, the solution to be tested is placed directly on the surface of the sensitive layer. The lead ions in the solution fully contact the black phosphorus and its surface-modified structure, rapidly completing the adsorption process without the need for complex sample pretreatment or concentration steps. In step 2, by testing the change in source-drain current, the concentration of lead ions in the solution can be determined based on the degree of conductivity response. The detection process does not rely on markers or additional chemical reactions, avoiding the cumbersome spectral analysis or electrochemical pretreatment operations in traditional detection methods. This method, based on the highly sensitive conductivity modulation mechanism of field-effect transistors, can achieve trace detection, real-time response, and quantitative analysis of lead ions. It is particularly suitable for applications such as portable and online water environment monitoring, and has the advantages of low detection limit, fast response, and high system integration.

[0017] Furthermore, in step 1, ultraviolet or visible light is applied to the sensitive layer. In this way, on the one hand, light can excite the photogenerated carriers of materials such as black phosphorus, noble metal particles and titanium dioxide nanoparticles in the sensitive layer, enhance their surface activity, and promote the binding reaction between lead ions and functional sites. Especially with the participation of titanium dioxide, a stronger Pb 2+ –OH or Pb 2+ On the other hand, light-induced electron-hole pairs can participate in the interfacial charge transfer process, amplifying the channel carrier perturbations caused by lead ion adsorption and making the source-drain current change more significant. Furthermore, light can excite gold nanoparticles to produce localized surface plasmon resonances, further enhancing the localized accumulation of lead ions on the sensitive layer surface and the electronic coupling. Therefore, by introducing a light-induced excitation mechanism during the lead ion adsorption process, the response signal is multiplied without changing the overall structure, improving the detector's ability to detect trace lead ions and its signal-to-noise ratio.

[0018] Furthermore, in step 2, source-drain current measurements are performed under no light conditions. Since photosensitive materials such as black phosphorus, gold nanoparticles, and titanium dioxide easily generate photogenerated carriers under light conditions, thereby inducing background current or additional conductivity changes, if continuous illumination is applied during the detection process, it is easy to cause the superposition effect of "photogenerated response" and "lead ion adsorption response" to be mixed into the electrical signal, thereby reducing the reliability of the detection results. By turning off the light source after the adsorption is completed and performing conductivity measurement in the dark state, the interference caused by light is shielded, ensuring that the change in source-drain current is only caused by lead ion adsorption, thereby achieving a pure electrical response to changes in lead ion concentration. In addition, dark-state detection can also reduce thermal noise, stabilize carrier mobility, and improve signal-to-noise ratio, making it suitable for high-precision quantitative analysis of low-concentration lead ions. Therefore, decoupling the measurement step from the illumination process can ensure that the detection data is more repeatable and accurate.

[0019] Furthermore, in step 1, the sensitive layer is heated using infrared radiation. This, on the one hand, increases the surface temperature of the sensitive layer and its surface functional materials (such as black phosphorus, gold nanoparticles, and titanium dioxide), thereby activating adsorption sites and increasing their binding activity with lead ions, making it easier for lead ions to coordinate or electrostatically interact with the functional sites. Furthermore, heating also increases the diffusion rate of lead ions in the test solution, accelerating their migration from the solution to the surface of the sensitive layer, thereby shortening response time and improving enrichment efficiency. As a non-contact heating method, infrared radiation offers advantages such as uniform heating, rapid temperature rise, and low power consumption. It can effectively heat localized areas without affecting the device structure and electrode connections. Therefore, introducing infrared heating during the adsorption process can enhance the interaction strength between lead ions and the sensitive layer, improving detection sensitivity and response speed.

[0020] Beneficial effects of the present invention: (1) The present invention uses black phosphorus as the sensitive material for field-effect transistors. Its high carrier mobility, wide adjustable band gap, and abundant lone-pair electrons make it highly sensitive to surface charge perturbations, making it suitable for detecting conductivity changes induced by metal ions. Black phosphorus has good chemical compatibility with lead ions, and the stable coordination between surface phosphorus atoms and lead ions causes a significant change in channel conductivity.

[0021] (2) The present invention introduces precious metal particles onto the surface of the black phosphorus sensitive layer, enhancing the selective adsorption capacity of lead ions. The surface of gold particles has a natural affinity for lead, providing a high density of adsorption sites and forming interfacial electronic coupling with black phosphorus, significantly amplifying the charge disturbance caused by lead ion adsorption.

[0022] (3) During the lead ion adsorption process, the present invention applies ultraviolet or visible light irradiation to stimulate photogenerated carriers in materials such as black phosphorus, gold nanoparticles, and titanium dioxide in the sensitive layer, thereby increasing surface activity and adsorption site reactivity, thereby accelerating the binding process of lead ions. Illumination can also excite the precious metal particles to produce a local surface plasmon resonance effect, enhancing the enrichment of lead ions in the sensitive layer and the electronic perturbation effect, thereby improving the adsorption efficiency and the sensitivity of the subsequent conductivity response.

[0023] (4) The present invention performs source-drain current measurement in a light-free environment after adsorption is completed, which helps to eliminate background interference caused by photogenerated carriers and ensures that the detection signal is generated only by the conductivity change caused by lead ion adsorption, thereby improving the accuracy and repeatability of the detection data.

[0024] In view of the above beneficial effects, the present invention has good application prospects in the field of lead ion detection technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a black phosphorus field-effect transistor lead ion detector.

[0026] In the figure: 1. Insulating substrate; 2. Gate electrode layer; 3. Gate electrode insulating layer; 4. Sensitive layer; 5. Source electrode; 6. Drain electrode; 7. Precious metal particles. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of this application more clear, the application is further described in detail below with reference to the accompanying drawings and examples.

[0028] Example 1 This embodiment provides a black phosphorus field effect tube lead ion detector, such as Figure 1 As shown, an insulating substrate 1 , a gate electrode layer 2 , a gate electrode insulating layer 3 , a sensitive layer 4 , a source electrode 5 , a drain electrode 6 , and precious metal particles 7 .

[0029] The insulating substrate 1 is a silicon wafer (Si) with excellent thermal stability and mechanical strength. A 300nm thick silicon dioxide (SiO2) layer is formed on the surface through thermal oxidation. This layer serves as an insulating layer and also serves as the gate electrode insulating layer 3. The gate electrode layer 2 is an aluminum (Al) layer deposited on the back of the silicon wafer via magnetron sputtering. It is approximately 100nm thick and serves as a global back-gate electrode, collaborating with the SiO2 layer to achieve electric field control. The sensitive layer 4 is a single or few-layer black phosphorus sheet with a thickness of 1–10nm. In this embodiment, a few-layer black phosphorus with a thickness of approximately 6nm is used. The black phosphorus sheet is placed on the gate electrode insulating layer 3 via mechanical stripping and dry transfer, forming the channel region.

[0030] To enhance the conductivity response sensitivity, the sensitive layer 4 is patterned into a strip structure. The strips are arranged along the line connecting the source electrode 5 and the drain electrode 6. Each strip is 1 μm wide, with a spacing of 1 μm, and there are 10–20 strips. This structure ensures a continuous carrier channel while increasing the specific surface area of ​​the edge sites, which is beneficial for lead ion adsorption and enhances conductivity perturbations.

[0031] The source electrode 5 and drain electrode 6 are prepared using electron beam lithography and metal thermal evaporation technology. The material is a titanium / gold (Ti / Au) stacked structure with thicknesses of 5nm and 45nm respectively. The electrode spacing is 2.5μm and the channel width is 10μm to ensure excellent current injection and electrical contact characteristics.

[0032] The surface of the sensitive layer 4 is modified with precious metal particles 7. In this example, gold nanoparticles with a particle size of 20 nm are used, prepared via an in-situ reduction method. The device is immersed in a mixed solution containing 0.5 mM chloroauric acid (HAuCl4) and 1.0 mM sodium citrate. The reaction is allowed to proceed in an 80°C water bath for 10 minutes, followed by removal, rinsing with deionized water, and drying with nitrogen. This method achieves a uniform distribution of gold nanoparticles on the surface of the black phosphorus strips.

[0033] During the use of the device, the target water sample (containing lead ions) is dripped into the sensitive layer 4 area. After standing for 3 minutes, the curve of source-drain current changing with gate voltage is measured by a semiconductor parameter analyzer.

[0034] Example 2 Based on Example 1, titanium dioxide nanoparticles with a particle size of 5–10 nm were introduced onto the surface of the black phosphorus sensitive layer 4 to enhance the lead ion adsorption efficiency and the device's conductivity response sensitivity. The specific method was as follows: After modifying the surface of the sensitive layer 4 with gold nanoparticles 7, the device was immersed in an aqueous solution containing polyethyleneimine (PEI) for 2 minutes to impart a positive surface charge. Subsequently, 2 μL of a 0.05 mg / mL dispersion of titanium dioxide nanoparticles in ethanol was added dropwise, and the mixture was heated at 70°C for 10 minutes to ensure uniform distribution of the nanoparticles and their stable adhesion to the sensitive surface.

[0035] The introduced titanium dioxide nanoparticles are rich in hydroxyl groups and oxygen vacancies on their surfaces, which can electrostatically adsorb and coordinate with lead ions, significantly improving their capture capacity. Furthermore, titanium dioxide, as an n-type semiconductor, can form a weak heterojunction with the p-type semiconductor black phosphorus. When lead ions are adsorbed and interfacial charge transfer occurs, this helps further amplify changes in the black phosphorus channel conductivity.

[0036] Example 3 Based on Example 1, the precious metal particles 7 were replaced with gold / titanium dioxide (Au@TiO2) core-shell nanoparticles to enhance the selective adsorption capacity and conductivity response sensitivity of lead ions. The specific preparation method is as follows: first, gold nanoparticles with a particle size of approximately 20 nm are synthesized as the core. Then, a TiO2 shell layer with a thickness of approximately 3–5 nm is coated on the surface using a sol-gel method to form Au@TiO2 core-shell particles with a particle size of approximately 25 nm. These particles are then dispersed in ethanol (concentration of 0.05 mg / mL) and drop-coated onto the surface of the sensitive layer 4 by electrostatic adsorption. After drying, a composite modified layer is formed.

[0037] The gold core possesses excellent conductivity and affinity for lead ions, significantly enhancing interfacial electronic coupling and lead ion adsorption efficiency. The TiO2 shell, rich in hydroxyl groups and oxygen vacancies, further provides enrichment sites and forms an n–p heterojunction with black phosphorus, facilitating charge transfer and conductivity amplification upon lead ion adsorption. Compared to using either gold or TiO2 alone, this core-shell structure effectively enhances the device's recognition and response to trace lead ions while maintaining the nanoparticle's dispersion and stability.

[0038] Example 4 This embodiment provides a method for using a black phosphorus field effect transistor lead ion detector, comprising the following steps: Step 1: Place the solution to be tested on the sensitive layer; Specifically, the prepared black phosphorus field-effect transistor device was placed on a horizontal test platform, and 5 μL of the test solution (containing lead ions, pH ≈ 6.5) was dripped onto the sensitive layer 4 using a microsyringe to cover the black phosphorus channel area. During the lead ion adsorption stage, the device was simultaneously irradiated with a 365nm ultraviolet light source or 400–600nm visible light, with an irradiation intensity controlled at 10–20mW / cm 2 The irradiation time is 3 minutes. Light irradiation can stimulate the electronic state activity of black phosphorus, gold particles, or TiO2 surfaces, increase the reactivity of surface adsorption sites, and induce photogenerated carriers to participate in the lead ion-interface binding process, thereby promoting the rapid adsorption and enrichment of lead ions on the surface of the sensitive layer.

[0039] Step 2: After the lead ion adsorption is completed, the source-drain current change is tested to determine the lead ion concentration in the solution.

[0040] Specifically, after the adsorption reaction is completed, the external light source is turned off and wait for about 30 seconds to allow the photogenerated carriers to fully recombine and return to a steady state. Under no-light conditions, a source-drain bias is applied and the gate voltage is scanned using a semiconductor parameter analyzer to record the curve of the source-drain current changing with the gate voltage. Compared with the baseline curve before the lead ion solution is added, if there is an obvious current increase or migration behavior, it can be determined that lead ions are present in the solution, and the concentration can be calculated using the calibration curve. This dark-state measurement process avoids the background interference current caused by light, ensures that the collected conductivity changes are only caused by lead ion adsorption, and improves the accuracy and repeatability of the detection.

[0041] This method utilizes a time-sequential separation strategy of light excitation + dark-state detection to improve the sensor's response rate and electrical signal resolution capability to trace lead ions, making it suitable for high-demand application scenarios such as online water quality monitoring and environmental toxicity screening.

[0042] Example 5 On the basis of Example 4, infrared heating is introduced into the lead ion adsorption step (step 1) to enhance the interaction between the lead ions and the sensitive layer 4, thereby further improving the adsorption efficiency and the source-drain current response amplitude.

[0043] Before the experiment begins, the black phosphorus field-effect transistor device is placed on a temperature-controlled infrared heating platform located below the sensitive layer 4. The heating wavelength range is 3–5 μm, corresponding to the mid-infrared band. The platform temperature is set to 45°C to ensure that the surface temperature of the sensitive layer is increased without destroying the black phosphorus structure and device stability. 5 μL of the test solution containing lead ions is added dropwise to the top of the sensitive layer, and ultraviolet or visible light irradiation is turned on at the same time (as described in Example 4, 365 nm, 15 mW / cm 2 ), the duration is 3 minutes.

[0044] During this process, infrared heating moderately raises the surface temperature of the sensitive layer 4, helping to activate surface sites on black phosphorus and functional particles (such as gold and TiO2), enhancing their affinity for lead ions. Heating also increases the diffusion rate of lead ions in the solution, promoting their accumulation on the black phosphorus surface within a limited timeframe, achieving a synergistic effect of both accelerated adsorption and enhanced interfacial reactions.

[0045] After the illumination and heating are completed, the light source and infrared heat source are turned off and the system is left to stand for 30 seconds to restore to thermal equilibrium. Then, the source-drain current measurement in the dark state (step 2) is performed, with the same specific parameters as in Example 4.

[0046] This embodiment further activates the interfacial reactivity of the sensitive layer 4 by introducing infrared heating, constructs a "thermal-photosynergistic adsorption + dark-state high-resolution measurement" mechanism, and provides a better technical path for the efficient, rapid and stable detection of trace heavy metal ions.

[0047] Preferably, a weak magnetic field control mechanism is further introduced to enhance the sensitive layer's lead ion adsorption efficiency and carrier response sensitivity, improving overall conductivity detection performance. Specifically, a pair of small permanent magnets are placed on either side of the black phosphorus field-effect transistor test platform (perpendicular to the line connecting the source electrode 5 and the drain electrode 6). This creates a static magnetic field perpendicular to the device channel, parallel to the black phosphorus channel plane and perpendicular to the direction of electron motion. The magnetic induction intensity is controlled between 0.02 and 0.1 Tesla. During source-drain current measurement, electrons move from the source electrode 5 to the drain electrode 6 (i.e., in the channel direction). Under the influence of the magnetic field, the electrons are subjected to a Lorentz force perpendicular to their direction of motion, causing vertical deflection, forming a transverse potential gradient (Hall effect), and causing carriers to locally concentrate in the channel, enhancing their response to charge perturbations caused by lead ion adsorption.

[0048] In summary, the present invention provides a black phosphorus field-effect transistor (BPFET) lead ion detector and its use method, which exhibit advantages such as a rational structure, high sensitivity, and fast response. The detector comprises an insulating substrate 1, a gate electrode layer 2, a gate electrode insulating layer 3, a sensitive layer 4, a source electrode 5, a drain electrode 6, and noble metal particles 7 disposed on the surface of the sensitive layer 4. The sensitive layer 4 utilizes a single or few layers of black phosphorus, exhibiting excellent electrical modulation properties and heavy metal ion selectivity. The noble metal particles 7 can be gold nanoparticles or an Au@TiO2 core-shell structure, enhancing lead ion enrichment and conductivity response capabilities. Furthermore, titanium dioxide nanoparticles with a particle size of 5–10 nm can be further introduced onto the black phosphorus surface to enhance interfacial functional synergy. In the accompanying use method, adsorption is promoted by applying ultraviolet or visible light, combined with infrared heating and dark-state measurement strategies, further improving detection efficiency and electrical signal accuracy. This method establishes a multifunctional heterogeneous interface and field-modulation synergistic mechanism, providing a feasible technical path for highly sensitive, low-interference, and repeatable electrical detection of trace lead ions, with broad application prospects.

[0049] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A black phosphorus field-effect transistor lead ion detector, comprising an insulating substrate, a gate electrode layer, a gate electrode insulating layer, a sensitive layer, a source electrode, and a drain electrode, wherein the gate electrode layer is disposed on the insulating substrate, and the sensitive layer is disposed on the gate electrode insulating layer, characterized in that: The sensitive layer includes black phosphorus material, and noble metal particles are provided on the surface of the sensitive layer.

2. The black phosphorus field effect transistor lead ion detector according to claim 1, characterized in that: The sensitive layer is a single layer or a few layers of black phosphorus sheet, and the thickness of the sensitive layer is 1-10 nm.

3. The black phosphorus field effect transistor lead ion detector according to claim 1, characterized in that: The noble metal particles are gold nanoparticles, and the particle size of the gold nanoparticles is 2-50 nm.

4. The black phosphorus field effect transistor lead ion detector according to claim 1, wherein: The sensitive layer is in a strip shape and is along the connection direction of the source electrode and the drain electrode.

5. The black phosphorus field effect transistor lead ion detector according to claim 1, characterized in that: It also includes titanium dioxide nanoparticles, which are distributed on the surface of the sensitive layer and have a particle size of 5-10 nm.

6. The black phosphorus field effect transistor lead ion detector according to claim 1, characterized in that: The noble metal particles are of a gold / titanium dioxide core-shell structure.

7. A method for using the black phosphorus field effect tube lead ion detector according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: placing the solution to be tested on the sensitive layer; Step 2: After the lead ion adsorption is completed, the source-drain current change is tested to determine the lead ion concentration in the solution.

8. The method for using the black phosphorus field effect tube lead ion detector according to claim 7, characterized in that: In step 1, ultraviolet or visible light irradiation is applied to the sensitive layer.

9. The method for using the black phosphorus field effect tube lead ion detector according to claim 8, characterized in that: In step 2, source-drain current measurements are performed under no-light conditions.

10. The method for using the black phosphorus field effect tube lead ion detector according to claim 9, characterized in that: In step 1, the sensitive layer is heated by infrared rays.

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