Black phosphorus nanosheets and their preparation methods, black phosphorus-modified interdigitated electrodes and their preparation methods and applications

Abstract

This invention proposes a method for preparing black phosphorus nanosheets, comprising the following steps: Step 1, preparing an electrolyte, including adding tetrabutylammonium hexafluorophosphate to an organic solvent to obtain an electrolyte; Step 2, electrochemical cathode stripping, including immersing the anode and cathode in the electrolyte, applying a direct current, and reacting to obtain a precipitate, which is the black phosphorus nanosheet; the cathode comprises black phosphorus. This invention also proposes a black phosphorus nanosheet, a black phosphorus-modified interdigitated electrode and its preparation method, and a multifunctional flexible sensor incorporating the interdigitated electrode. The method for preparing black phosphorus nanosheets provided by this invention has high production efficiency and is expected to be applied to large-scale industrial production. The multifunctional flexible sensor can respond to breathing frequency, light, and strain with high responsivity, realizing the fabrication of multifunctional integrated devices.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a black phosphorus nanosheet and its preparation method, a black phosphorus-modified interdigitated electrode and its preparation method, and a multifunctional flexible sensor incorporating the interdigitated electrode. Background Technology

[0002] As a novel two-dimensional material, black phosphorus has attracted widespread attention due to its superior physical properties. As a two-dimensional semiconductor material with a layered, honeycomb-like wrinkled structure, black phosphorus shows promising applications in optics, electronics, and mechanics. Optically, black phosphorus possesses a thickness-dependent tunable direct bandgap, adjustable from 0.3 eV for bulk materials to 2 eV for monolayers, covering the visible to infrared wavelengths. Electrically, black phosphorus exhibits a high hole carrier mobility (1000 cm⁻¹). 2 V -1 s -1 In terms of mechanics, black phosphorus exhibits in-plane anisotropy, and its unique wrinkled structure endows it with novel mechanical properties, such as in-plane anisotropy of negative Poisson's ratio and Young's modulus. In summary, the rich physical properties of black phosphorus make it a promising candidate for applications in flexible electronic devices. It holds significant importance in both academic research and practical applications.

[0003] CN105116034A discloses a sensor based on a black phosphorus electrode and its preparation method. The main steps include: 1. preparing black phosphorus; 2. impregnating black phosphorus with an organic solvent; 3. preparing a black phosphorus electrode; and 4. preparing the sensor. The black phosphorus electrode-based sensor of this invention can prevent oxygen or oxides from directly contacting black phosphorus, thus leveraging the excellent electrochemical detection performance of black phosphorus. This provides a foundation for the application of black phosphorus electrodes and black phosphorus electrode-based sensors, and has broad application prospects.

[0004] CN111664974A discloses a black phosphorus flexible stress sensor and its preparation method, belonging to the field of flexible stress sensor technology. Specifically, black phosphorus grains are spin-coated onto a substrate, and the substrate, along with red phosphorus, iodine, and tin, is placed into a quartz tube and sealed. After heating at normal pressure and holding at that temperature for a certain time, a black phosphorus film is obtained. The black phosphorus film is then encapsulated in an upper PDMS microfilm substrate and a lower patterned PDMS microfilm substrate, and electrodes are connected to prepare a flexible pressure sensor. The PDMS microfilm is patterned using FIB technology. This invention forms a large number of nucleation points on the substrate surface, which greatly increases the film area and film quality of black phosphorus on the substrate surface. The black phosphorus film is suspended, increasing the film strain and thus improving the sensing performance, thereby flexibly and conveniently realizing an ultra-sensitive flexible stress sensor.

[0005] CN111189801A discloses a black phosphorus-based fiber optic humidity sensor and its fabrication method, comprising a single-mode fiber and a photonic crystal fiber, with one end of the single-mode fiber fused to the other end of the photonic crystal fiber. The single-mode fiber and the photonic crystal fiber constitute an inline fiber Michelson intermodal interferometer. The air holes in the photonic crystal fiber are filled with black phosphorus-polyvinyl alcohol. The detection principle is that when the black phosphorus-polyvinyl alcohol filled in the air holes interacts with external moisture, it changes the propagation constants of each mode in the photonic crystal fiber, modulating the interference fringes of the inline fiber Michelson intermodal interferometer. By detecting the changes in the output spectrum of the black phosphorus-based fiber optic humidity sensor, information on changes in ambient humidity can be obtained. This invention has a simple structure and process, is easy to operate, has low cost, and high sensitivity, and can be applied to the field of humidity measurement.

[0006] CN111678953A discloses a method for fabricating a resistive gas sensor based on black phosphorus quantum dots, belonging to the field of gas-sensitive sensors. It aims to address the problems of low automation, high cost, and large equipment size in existing detection methods for phosphorus-containing organic toxic gases. The method includes: 1. Fabrication of black phosphorus quantum dots; 2. Fabrication of the base plate in the sensor; 3. Fabrication of the copper heating electrode in the sensor; 4. Fabrication of the insulating and thermally conductive film in the sensor; 5. Fabrication of the silver cross-finger electrode in the sensor; 6. Dropping a black phosphorus quantum dot solution onto the silver cross-finger electrode to form a black phosphorus film, and then attaching a polyimide film tape to one side of the black phosphorus film. The sensor prepared by this invention shows a significant response to DMMP vapor, exhibiting high sensitivity and possessing the capability to detect DMMP vapor. The sensor of this invention has advantages such as small size, high automation, long-term use, good repeatability, and high sensitivity. This invention is applied to the detection of vapor generated by the volatilization of phosphorus-containing organic compounds.

[0007] CN110794006A discloses a molybdenum disulfide-black phosphorus composite material, its preparation method, and its application in NO2 gas sensors, belonging to the field of materials preparation. A method for preparing the molybdenum disulfide-black phosphorus composite material includes the following steps: 1) dispersing black phosphorus nanosheets in dimethylformamide and adding ammonium tetrathiomolybdate to obtain a reaction solution; 2) pouring the reaction solution into a reaction vessel and carrying out a solvothermal reaction, purifying and drying the resulting reaction product to obtain the molybdenum disulfide-black phosphorus composite material. The molybdenum disulfide-black phosphorus composite material prepared by the method of this invention has a stable structure and uniform morphology. The application of the invented molybdenum disulfide-black phosphorus composite material as a gas-sensitive material in NO2 gas sensors shows significant response and good selectivity to ppb-level NO2 at room temperature, demonstrating great application potential in the field of gas sensing.

[0008] CN106018851A discloses a method for preparing and applying a steroid immunosensor based on sheet-like black phosphorus, belonging to the field of novel biosensing and detection technology. Sheet-like black phosphorus has a graphene-like structure and excellent conductivity. An ionic liquid is used as a dispersant for the sheet-like black phosphorus, which is then applied to the substrate of the immunosensor. A porous PtAu alloy membrane is used to firmly bind the underlying material and the antibody, enhancing the stability of the sensor. Using potassium ferricyanide as the signal from the underlying solution, ultrasensitive detection of steroids is achieved.

[0009] However, existing black phosphorus-based flexible sensors have the following drawbacks: (1) There are no reports on black phosphorus-based respiratory sensors; (2) Existing black phosphorus-based devices have limited functionality (see Angewandte Chemie International Edition, 2015, 54, 14317-14320; Advanced Functional Materials, 2021, 31, 2106484), and cannot achieve multifunctional integration. Summary of the Invention

[0010] To address the aforementioned problems in the prior art, this invention proposes a black phosphorus nanosheet, its preparation method, an interdigitated electrode based on the black phosphorus nanosheet film, and a multifunctional flexible sensor incorporating the interdigitated electrode. The preparation method provided by this invention uses readily available raw materials and involves a simple process. The prepared sensor can be used in fields such as respiratory, photoelectric, and pressure sensing, providing a device prototype for subsequent practical applications of black phosphorus.

[0011] Therefore, in a first aspect, the present invention provides a method for preparing black phosphorus nanosheets, comprising the following steps:

[0012] Step 1: Prepare the electrolyte, including adding tetrabutylammonium hexafluorophosphate to an organic solvent to obtain the electrolyte;

[0013] Step 2, electrochemical cathode stripping, includes: immersing the anode and cathode in the electrolyte, applying a direct current, and reacting to obtain a precipitate, namely black phosphorus nanosheets;

[0014] The cathode comprises black phosphorus.

[0015] As a specific embodiment of the present invention, preferably, the tetrabutylammonium hexafluorophosphate is tetra-n-butylammonium hexafluorophosphate; and / or the organic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, N,N-diethylformamide, and N,N-dimethylacetamide, preferably N,N-dimethylformamide.

[0016] As a specific embodiment of the present invention, preferably, the concentration of tetrabutylammonium hexafluorophosphate in the electrolyte is 10-50 mg / 10 mL, more preferably 10-40 mg / 10 mL, and even more preferably 10-38.7 mg / 10 mL.

[0017] As a specific embodiment of the present invention, preferably, the preparation of electrolyte in step 1 is carried out at 20-35°C, and more preferably at 20-25°C.

[0018] As a specific embodiment of the present invention, preferably, the black phosphorus is black phosphorus crystal; and / or the anode comprises platinum, preferably a platinum electrode.

[0019] As a specific embodiment of the present invention, preferably, the distance between the anode and the cathode in step 2 is 0.5-3 cm, more preferably 1-2 cm, and / or the current density is 0.001-0.01 A / cm², and / or the reaction time is 1-3 hours.

[0020] As a specific embodiment of the present invention, preferably, step 2 further includes washing the precipitate, preferably, the solvent used for washing includes at least one of isopropanol and N,N-dimethylformamide.

[0021] Therefore, in a second aspect, the present invention provides a black phosphorus nanosheet prepared by the above-described preparation method, having a lateral dimension of 1-40 μm, preferably 1-20 μm, and a thickness of 1-30 nanometers, preferably 1-10 nanometers. The lateral dimension refers to the straight-line distance between the two farthest points on the sheet.

[0022] Therefore, in a third aspect, the present invention provides a black phosphorus-modified interdigitated electrode, comprising an interdigitated electrode substrate and a black phosphorus nanosheet film disposed on the interdigitated electrode substrate, wherein the black phosphorus nanosheet film comprises black phosphorus nanosheets prepared by the above-described preparation method or the above-described black phosphorus nanosheets.

[0023] In a specific embodiment of the present invention, preferably, the interdigitated electrode substrate is a flexible polyethylene terephthalate interdigitated electrode.

[0024] Therefore, in a fourth aspect, the present invention provides a method for preparing an interdigitated electrode, comprising the following steps:

[0025] (1) The black phosphorus nanosheets prepared by the above preparation method or the above black phosphorus nanosheets are dispersed in an alcohol solvent to obtain a black phosphorus nanosheet dispersion.

[0026] (2) The black phosphorus nanosheet dispersion is dropped onto the interdigitated electrode, dried to form a film, and then surface encapsulated to obtain an interdigitated electrode based on a black phosphorus nanosheet film.

[0027] As a specific embodiment of the present invention, preferably, the alcohol solvent is selected from at least one of isopropanol and ethanol, preferably, the oxygen concentration in the alcohol solvent is less than 0.1 ppm, and / or the concentration of the black phosphorus nanosheet dispersion is 1-2 mg / mL, and / or the surface encapsulation is a polydimethylsiloxane film, preferably, the thickness of the polydimethylsiloxane film is 10-30 micrometers, for example, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, or 30 micrometers.

[0028] Therefore, in a fifth aspect, the present invention provides a multifunctional sensor comprising an interdigital electrode prepared by the above-described preparation method, or the above-described interdigital electrode.

[0029] In a specific embodiment of the present invention, preferably, the multifunctional sensor is a multifunctional black phosphorus-based flexible sensor; more preferably, the preparation method of the multifunctional black phosphorus-based flexible sensor includes the following steps:

[0030] (1) Tetra-n-butylammonium hexafluorophosphate was prepared with N,N-dimethylformamide solvent to obtain mixture A;

[0031] (2) Platinum electrodes and black phosphorus crystals were inserted into the mixture A, serving as the anode and cathode respectively, and connected to a galvanometer, with the distance between the two electrodes maintained at 2 cm. The current density was controlled by the galvanometer, and expansion of the crystals was observed. As the reaction proceeded, the black phosphorus crystals continuously expanded and detached from the electrodes into the mixture A, resulting in mixture B;

[0032] (5) The mixture B was centrifuged and washed with N,N-dimethylformamide and isopropanol respectively. The resulting solid was dried and dispersed in isopropanol with an oxygen concentration of less than 0.1 ppm to obtain a black phosphorus nanosheet dispersion.

[0033] (6) The black phosphorus nanosheet dispersion is added dropwise to the polyethylene terephthalate interdigitated electrode and dried in a glove box to form a film. This process continues until the electrode is conductive. A polydimethylsiloxane film is then encapsulated on the surface of the resulting film to obtain an interdigitated electrode based on the black phosphorus nanosheet film.

[0034] (7) Connect the black phosphorus nanosheet thin film device to an electrochemical workstation to obtain a black phosphorus nanosheet thin film sensor device. Then, fix the applied voltage and test the current change under different breathing frequencies, different wavelengths of light, and different strains, and calculate the corresponding responsivity.

[0035] The beneficial effects of this invention are as follows:

[0036] (1) The method for preparing black phosphorus nanosheets provided by the present invention has high production efficiency and is expected to be applied to large-scale industrial production.

[0037] (2) The flexible sensor based on black phosphorus nanofilm provided by the present invention can respond to breathing frequency, light and strain, and has a high responsivity, realizing the fabrication of a multifunctional integrated device.

[0038] (3) The polydimethylsiloxane film encapsulated on the surface of the interdigitated electrode provided by the present invention ensures the stability of the device. Attached Figure Description

[0039] Figure 1(a) is a transmission electron microscope image of the black phosphorus nanosheets in Example 1.

[0040] Figure 1(b) is a scanning electron microscope image of the black phosphorus nanosheet film in Example 1.

[0041] Figure 1(c) is a statistical chart of the lateral dimensions of black phosphorus nanosheets in Example 1.

[0042] Figure 1(d) is a statistical graph of the thickness of black phosphorus nanosheets in Example 1.

[0043] Figure 2 This is a Raman image of the black phosphorus nanosheet film in Example 1.

[0044] Figure 3 The image shows the X-ray diffraction pattern of the black phosphorus nanosheet film in Example 1.

[0045] Figure 4 The graph shows the sensing performance of the sensor based on black phosphorus nanosheet film in Example 1 at different breathing frequencies.

[0046] Figure 5 This is a display of the sensing performance of the black phosphorus nanosheet thin film-based sensor in Example 1 at different wavelengths under the same light intensity.

[0047] Figure 6 The graph shows the sensing performance of the sensor based on black phosphorus nanosheet film in Example 1 under different strains.

[0048] Figure 7 This is a Raman image of the black phosphorus nanosheet film in Example 2.

[0049] Figure 8 This is a diagram showing the respiratory sensing performance of the sensor device based on black phosphorus nanosheet film in Example 2.

[0050] Figure 9 This is a Raman image of the black phosphorus nanosheet film in Example 3.

[0051] Figure 10This is a diagram showing the respiratory sensing performance of the sensor device based on black phosphorus nanosheet film in Example 3.

[0052] Figure 11 This is a Raman image of the black phosphorus nanosheet film in Example 4.

[0053] Figure 12 This is a diagram showing the respiratory sensing performance of the sensor device based on black phosphorus nanosheet film in Example 4.

[0054] Figure 13 This is a Raman image of the black phosphorus nanosheet film in Example 5.

[0055] Figure 14 This is a diagram showing the respiratory sensing performance of the sensor device based on black phosphorus nanosheet film in Example 5.

[0056] Figure 15 This is a transmission electron microscope image of the black phosphorus nanosheets in Comparative Example 1.

[0057] Figure 16 The diagram shows the respiratory sensing performance of the sensor based on black phosphorus nanosheet film in Comparative Example 1.

[0058] Figure 17 This is a scanning electron microscope image of the black phosphorus nanosheet film in Comparative Example 2.

[0059] Figure 18 The diagram shows the respiratory sensing performance of the sensor based on black phosphorus nanosheet film in Comparative Example 3. Detailed Implementation

[0060] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0061] Example 1

[0062] (1) Using tetra-n-butylhexafluorophosphate as raw material, at 25°C, N,N-dimethylformamide is used as solvent to prepare a tetra-n-butylhexafluorophosphate solution, which is the electrolyte.

[0063] (2) Place 10 ml of the electrolyte in a 50 ml beaker, then use black phosphorus crystals as the cathode and a platinum electrode as the anode. The distance between the two electrodes is 2 cm. Control the current density at 0.004 A / cm² and react for 3 hours.

[0064] (3) After repeatedly washing the precipitate obtained after the reaction with N,N dimethylformamide and isopropanol, black phosphorus nanosheets were obtained.

[0065] (4) Disperse black phosphorus nanosheets at 25°C in isopropanol with an oxygen concentration of less than 0.1 ppm and sonicate for 20 minutes to obtain a black phosphorus nanosheet dispersion with a concentration of 1.5 mg / mL.

[0066] (5) In a glove box at 25°C, the black phosphorus nano-dispersion was dripped dropwise at a rate of 10 μL onto a flexible polyethylene terephthalate interdigitated electrode, and dried in the glove box at 25°C until the electrode was conductive, thus obtaining an interdigitated electrode coated with a black phosphorus nanosheet film. Subsequently, a 20 μm thick polydimethylsiloxane film was encapsulated on the electrode surface using electrostatic force to obtain the interdigitated electrode (flexible electrode) based on the black phosphorus nanosheet film.

[0067] (6) First, the black phosphorus nanosheet thin film interdigitated electrode prepared in step (5) was connected to the SJ Shenju AF250FF46-2 wire using TED PELLA-JY16031 silver paste from the United States. Then, the flexible electrode was connected to the Shanghai Chenhua CHI660E electrochemical workstation through the same wire to form a sensor device based on black phosphorus nanosheet thin film (flexible sensor device). The response of the sensor device to different breathing frequencies, different wavelengths of light (470-940 nm), and different strains (0.05%-0.2%) was then tested at a constant voltage of +10V. The test results are shown in Figure 4. Figure 5 and Figure 6 The responsivity is defined as the ratio of the change in current under constant voltage to the initial current (see ACS Nano, 2015, 9, 10, 9898–9905).

[0068] The black phosphorus nanosheets prepared in step (3) were characterized by transmission electron microscopy, and the transmission electron microscopy image of the black phosphorus nanosheets shown in Figure 1(a) was obtained. The image shows that the black phosphorus nanosheets are in good crystalline state. The lateral dimensions of the black phosphorus nanosheets were statistically analyzed by optical microscopy, and the results shown in Figure 1(c) were obtained. From Figure 1(c), it can be seen that the average lateral dimension of the black phosphorus nanosheets is 16.61 micrometers. The thickness of the black phosphorus nanosheets was further statistically analyzed by atomic force microscopy, and the results shown in Figure 1(d) were obtained. From Figure 1(d), it can be seen that the thickness distribution of the black phosphorus nanosheets is uniform, and the average thickness is 4.18 nanometers.

[0069] The interdigitated electrode coated with black phosphorus nanosheet film (before encapsulation) prepared in step (4) was characterized by scanning electron microscopy, and the scanning electron microscopy image of the black phosphorus nanosheet film shown in Figure 1(b) was obtained. The image shows that the surface of the black phosphorus nanosheet film is flat and has high quality.

[0070] Figure 2 and Figure 3The X-ray diffraction pattern and Raman pattern of the black phosphorus nanosheet film in Example 1 are shown respectively, both of which show good crystallinity.

[0071] Figure 4 The graph shows the sensing performance of the black phosphorus nanosheet thin film-based sensor in Example 1 at different breathing frequencies. The breathing sensing test results show that the sensor has good recognition accuracy under different breathing modes, including deep breathing, normal breathing, and rapid breathing.

[0072] Figure 5 The image shows the sensing performance of the black phosphorus nanosheet thin film-based sensor in Example 1 at different wavelengths under the same light intensity. The photoelectric sensing test results show that the sensor can achieve a response in a wide wavelength range of 470-940 nm under the same light intensity (4 milliwatts).

[0073] Figure 6 The diagram shows the sensing performance of the black phosphorus nanosheet thin film-based sensor in Example 1 under different strains. The pressure sensing test results show that the sensor can exhibit a current response proportional to the tensile strain.

[0074] The test results above demonstrate that the interdigitated electrodes based on black phosphorus nanosheet films prepared in this embodiment can be constructed as flexible multifunctional sensor devices, such as flexible respiratory sensor devices, flexible photoelectric sensor devices, and flexible pressure sensor devices, thereby enabling their use in different application environments.

[0075] Example 2

[0076] (1) Using tetra-n-butylhexafluorophosphate as raw material, at 25°C, N,N-dimethylformamide is used as solvent to prepare a 10 mg / 10 mL tetra-n-butylhexafluorophosphate solution, which is the electrolyte.

[0077] (2) Place 10 ml of the electrolyte in a 50 ml beaker, then use black phosphorus crystals as the cathode and a platinum electrode as the anode. The distance between the two electrodes is 2 cm. Control the current density at 0.001 A / cm² and react for 1 hour.

[0078] (3) After repeatedly washing the precipitate obtained after the reaction with N,N dimethylformamide and isopropanol, black phosphorus nanosheets were obtained.

[0079] (4) Disperse black phosphorus nanosheets at 25°C in isopropanol with an oxygen concentration of less than 0.1 ppm and sonicate for 20 minutes to obtain a black phosphorus nanosheet dispersion with a concentration of 1.5 mg / mL.

[0080] (5) In a glove box at 25°C, the black phosphorus nano-dispersion was dripped dropwise at a rate of 10 μL onto a flexible polyethylene terephthalate interdigitated electrode, and dried in the glove box at 25°C until the electrode was conductive, thus obtaining an interdigitated electrode coated with a black phosphorus nanosheet film. Subsequently, a 20 μm thick polydimethylsiloxane film was encapsulated on the electrode surface using electrostatic force to obtain the interdigitated electrode based on the black phosphorus nanosheet film.

[0081] (6) First, the black phosphorus nanosheet thin film interdigitated electrode prepared in step (5) was connected to the SJ Shenju AF250FF46-2 wire using TED PELLA-JY16031 silver paste from the United States. Then, the flexible electrode was connected to the Shanghai Chenhua CHI660E electrochemical workstation through the same wire to form a sensor device (flexible sensor device) based on black phosphorus nanosheet thin film. Then, the response of the sensor to different breathing frequencies, different wavelengths of light (470-940 nm), and different strains (0.05%-0.2%) was tested at a constant voltage of +10V.

[0082] Figure 7 The image shows the Raman spectrum of the black phosphorus nanosheet film in Example 2, indicating its good crystallinity.

[0083] Figure 8 The graphs show the sensing performance of the sensor device constructed based on black phosphorus nanosheet film in Example 2 at different breathing frequencies. The breathing sensing test results show that the sensor device has good recognition accuracy in different breathing modes, including deep breathing, normal breathing, and rapid breathing. The photoelectric sensing test results show that the sensor device based on black phosphorus nanosheet film can achieve a response in a wide wavelength range of 470-940 nm under the same light intensity (4 mW). The pressure sensing test results show that the sensor device can exhibit a current response proportional to tensile strain, but both the photoelectric and pressure responses are smaller than those in Example 1.

[0084] Example 3:

[0085] (1) Using tetra-n-butylhexafluorophosphate as raw material, at 25°C, N,N-dimethylformamide is used as solvent to prepare a 10 mg / 10 mL tetra-n-butylhexafluorophosphate solution, which is the electrolyte.

[0086] (2) Place 10 ml of the tetra-n-butylammonium hexafluorophosphate electrolyte into a 50 ml beaker, then use black phosphorus crystals as the cathode and platinum electrodes as the anode. The distance between the two electrodes is 2 cm. Control the current density at 0.01 A / cm² and react for 3 hours.

[0087] (3) After repeatedly washing the precipitate obtained after the reaction with N,N dimethylformamide and isopropanol, black phosphorus nanosheets were obtained.

[0088] (4) Disperse black phosphorus nanosheets at 25°C in isopropanol with an oxygen concentration of less than 0.1 ppm and sonicate for 20 minutes to obtain a black phosphorus nanosheet dispersion with a concentration of 1.5 mg / mL.

[0089] (5) In a glove box at 25°C, the black phosphorus nano-dispersion was dripped dropwise at a rate of 10 μL onto a flexible polyethylene terephthalate interdigitated electrode, and dried in the glove box at 25°C until the electrode was conductive, thus obtaining an interdigitated electrode coated with a black phosphorus nanosheet film. Subsequently, a 20 μm thick polydimethylsiloxane film was encapsulated on the electrode surface using electrostatic force to obtain the interdigitated electrode based on the black phosphorus nanosheet film.

[0090] (6) First, the black phosphorus nanosheet thin film interdigitated electrode prepared in step (5) was connected to the SJ Shenju AF250FF46-2 wire using TED PELLA-JY16031 silver paste from the United States. Then, the flexible electrode was connected to the Shanghai Chenhua CHI660E electrochemical workstation through the same wire to form a sensor device (flexible sensor device) based on black phosphorus nanosheet thin film. Then, the response of the sensor to different breathing frequencies, different wavelengths of light (470-940 nm), and different strains (0.05%-0.2%) was tested at a constant voltage of +10V.

[0091] Figure 9 The image shows the Raman spectrum of the black phosphorus nanosheet film in Example 3, indicating its good crystallinity.

[0092] Figure 10 The graph shows the sensing performance of the flexible respiratory sensor based on black phosphorus nanosheet film in Example 3 at different breathing frequencies. The respiratory sensing test results show that the sensor has good recognition accuracy in different breathing modes, including deep breathing, normal breathing, and rapid breathing. The photoelectric sensing test results show that the sensor based on black phosphorus nanosheet film can respond in a wide wavelength range of 470-940 nm under the same light intensity (4 mW). The pressure sensing test results show that the sensor can exhibit a current response proportional to tensile strain, but both the photoelectric and pressure responses are smaller than those in Example 1.

[0093] Example 4:

[0094] (1) Using tetra-n-butylhexafluorophosphate as raw material, at 25°C, N,N-dimethylformamide is used as solvent to prepare a 20 mg / 10 mL tetra-n-butylhexafluorophosphate solution, which is the electrolyte.

[0095] (2) The electrolyte was placed in a 50 ml beaker, and then black phosphorus crystals were used as the cathode and platinum electrodes as the anode. The distance between the two electrodes was 2 cm. The current density was controlled at 0.004 A / cm², and the reaction was carried out for 3 hours.

[0096] (3) After repeatedly washing the precipitate obtained after the reaction with N,N dimethylformamide and isopropanol, black phosphorus nanosheets were obtained.

[0097] (4) Disperse black phosphorus nanosheets at 25°C in isopropanol with an oxygen concentration of less than 0.1 ppm and sonicate for 20 minutes to obtain a black phosphorus nanosheet dispersion with a concentration of 1.5 mg / mL.

[0098] (5) In a glove box at 25°C, the black phosphorus nano-dispersion was dripped dropwise at a rate of 10 μL onto a flexible polyethylene terephthalate interdigitated electrode, and dried in the glove box at 25°C until the electrode was conductive, thus obtaining an interdigitated electrode coated with a black phosphorus nanosheet film. Subsequently, a 20 μm thick polydimethylsiloxane film was encapsulated on the electrode surface using electrostatic force to obtain the flexible black phosphorus nanosheet film interdigitated electrode.

[0099] (6) First, the black phosphorus nanosheet thin film interdigitated electrode prepared in step (5) was connected to the SJ Shenju AF250FF46-2 wire using TED PELLA-JY16031 silver paste from the United States. Then, the flexible electrode was connected to the Shanghai Chenhua CHI660E electrochemical workstation through the same wire to form a sensor device (flexible sensor device) based on black phosphorus nanosheet thin film. Then, the response of the sensor to different breathing frequencies, different wavelengths of light (470-940 nm), and different strains (0.05%-0.2%) was tested at a constant voltage of +10V.

[0100] Figure 11 The image shows the Raman spectrum of the black phosphorus nanosheet film in Example 4, indicating its good crystallinity.

[0101] Figure 12 The graph shows the sensing performance of the flexible respiratory sensor based on black phosphorus nanosheet film in Example 4 at different breathing frequencies. The respiratory sensing test results show that the sensor has good recognition accuracy in different breathing modes, including deep breathing, normal breathing, and rapid breathing. The photoelectric sensing test results show that the sensor based on black phosphorus nanosheet film can respond in a wide wavelength range of 470-940 nm under the same light intensity (4 mW). The pressure sensing test results show that the sensor can exhibit a current response proportional to tensile strain, but both the photoelectric and pressure responses are smaller than those in Example 1.

[0102] Example 5:

[0103] (1) Using tetra-n-butylammonium hexafluorophosphate and black phosphorus crystals as raw materials, at 25°C, a tetra-n-butylammonium hexafluorophosphate solution of 38.7 mg / 10 mL was prepared as the electrolyte using N,N dimethylformamide as the solvent.

[0104] (2) The electrolyte was placed in a 50 ml beaker, and then black phosphorus crystals were used as the cathode and platinum electrodes as the anode. The distance between the two electrodes was 2 cm. The current density was controlled at 0.01 A / cm², and the reaction was carried out for 3 hours.

[0105] (3) After repeatedly washing the precipitate obtained after the reaction with N,N dimethylformamide and isopropanol, black phosphorus nanosheets were obtained.

[0106] (4) Disperse black phosphorus nanosheets in isopropanol with an oxygen concentration of less than 0.1 ppm to obtain a black phosphorus nanosheet dispersion with a concentration of 1.5 mg / mL.

[0107] (5) In a glove box at 25°C, the black phosphorus nano-dispersion was dripped dropwise at a rate of 10 μL onto a flexible polyethylene terephthalate interdigitated electrode, and dried in the glove box at 25°C until the electrode was conductive, thus obtaining an interdigitated electrode coated with a black phosphorus nanosheet film. Subsequently, a 20 μm thick polydimethylsiloxane film was encapsulated on the electrode surface using electrostatic force to obtain a flexible interdigitated electrode based on a black phosphorus nanosheet film.

[0108] (6) First, the black phosphorus nanosheet thin film interdigitated electrode prepared in step (5) was connected to the SJ Shenju AF250FF46-2 wire using TED PELLA-JY16031 silver paste from the United States. Then, the flexible electrode was connected to the Shanghai Chenhua CHI660E electrochemical workstation through the same wire to form a sensor device (flexible sensor device) based on black phosphorus nanosheet thin film. Then, the response of the sensor to different breathing frequencies, different wavelengths of light (470-940 nm), and different strains (0.05%-0.2%) was tested at a constant voltage of +10V.

[0109] Figure 13 The image shows the Raman spectrum of the black phosphorus nanosheet film in Example 5, indicating its good crystallinity.

[0110] Figure 14 The graph shows the sensing performance of the flexible respiratory sensor based on black phosphorus nanosheet film in Example 5 at different breathing frequencies. The respiratory sensing test results show that the sensor has good recognition accuracy in different breathing modes, including deep breathing, normal breathing, and rapid breathing. The photoelectric sensing test results show that the sensor based on black phosphorus nanosheet film can respond in a wide wavelength range of 470-940 nm under the same light intensity (4 mW). The pressure sensing test results show that the sensor can exhibit a current response proportional to tensile strain, but both the photoelectric and pressure responses are smaller than those in Example 1.

[0111] Comparative Example 1

[0112] The difference from Example 1 is that N,N-dimethylformamide is replaced with acetonitrile.

[0113] (1) Using tetra-n-butylhexafluorophosphate as raw material, at 25°C and with acetonitrile as solvent, prepare a tetra-n-butylhexafluorophosphate solution of 38.7 mg / 10 mL, which is the electrolyte.

[0114] (2) Place 10 ml of the electrolyte in a 50 ml beaker, then use black phosphorus crystals as the cathode and a platinum electrode as the anode. The distance between the two electrodes is 2 cm. Control the current density at 0.004 A / cm² and react for 3 hours.

[0115] (3) After the precipitate obtained after the reaction was repeatedly washed with acetonitrile and isopropanol, black phosphorus nanosheets were obtained.

[0116] (4) Disperse black phosphorus nanosheets at 25°C in isopropanol with an oxygen concentration of less than 0.1 ppm and sonicate for 20 minutes to obtain a black phosphorus nanosheet dispersion with a concentration of 1.5 mg / mL.

[0117] (5) In a glove box at 25°C, the black phosphorus nano-dispersion was dripped dropwise at a rate of 10 μL onto a flexible polyethylene terephthalate interdigitated electrode, and dried in the glove box at 25°C until the electrode was conductive, thus obtaining an interdigitated electrode coated with a black phosphorus nanosheet film. Subsequently, a 20 μm thick polydimethylsiloxane film was encapsulated on the electrode surface using electrostatic force to obtain a flexible interdigitated electrode based on a black phosphorus nanosheet film.

[0118] (6) First, the black phosphorus nanosheet thin film interdigitated electrode prepared in step (5) was connected to the SJ Shenju AF250FF46-2 wire using TED PELLA-JY16031 silver paste from the United States. Then, the flexible electrode was connected to the Shanghai Chenhua CHI660E electrochemical workstation through the same wire to form a sensor device (flexible sensor device) based on black phosphorus nanosheet thin film. Then, the response of the sensor to different breathing frequencies, different wavelengths of light (470-940 nm), and different strains (0.05%-0.2%) was tested at a constant voltage of +10V.

[0119] Figure 15 The image shown is a transmission electron microscope (TEM) image of the black phosphorus nanosheet film in Comparative Example 1, revealing oxidation on the film surface and impurities introduced by acetonitrile during the intercalation process.

[0120] Figure 16The diagram shows the respiratory sensing performance of the sensor based on black phosphorus nanosheet film in Comparative Example 1. The results show a responsivity of less than 4. Photoelectric sensing results show that the sensor based on black phosphorus nanosheet film can achieve a response in a wide wavelength range of 470-940 nm under the same light intensity (4 mW). Pressure sensing results show that the sensor can exhibit a current response proportional to tensile strain, but both the photoelectric and pressure responses are much smaller than those in Example 1.

[0121] Comparative Example 2

[0122] The difference from Example 1 is that the interdigitated electrodes are replaced with polydimethylsiloxane interdigitated electrodes instead of flexible polyethylene terephthalate.

[0123] (1) Using tetra-n-butylammonium hexafluorophosphate as raw material, at room temperature and with isopropanol as solvent, prepare a tetra-n-butylammonium hexafluorophosphate solution of 38.7 mg / 10 mL, which is the electrolyte.

[0124] (2) Place 10 ml of the electrolyte in a 50 ml beaker, then use black phosphorus crystals as the cathode and a platinum electrode as the anode. The distance between the two electrodes is 2 cm. Control the current density at 0.004 A / cm² and react for 3 hours.

[0125] (3) After the precipitate obtained after the reaction was repeatedly washed with acetonitrile and isopropanol, black phosphorus nanosheets were obtained.

[0126] (4) Disperse black phosphorus nanosheets at 25°C in isopropanol with an oxygen concentration of less than 0.1 ppm and sonicate for 20 minutes to obtain a black phosphorus nanosheet dispersion with a concentration of 1.5 mg / mL.

[0127] (5) Black phosphorus nano-dispersion was dropped onto a 20-micrometer-thick polydimethylsiloxane thin film interdigitated electrode at 25°C in a glove box at a rate of 10 microliters per drop. However, the black phosphorus nanosheets under this comparative condition had poor film-forming effect and could not make the electrode conductive, thus failing to realize the fabrication and functional realization of the corresponding flexible device.

[0128] Figure 17 The image shows a scanning electron microscope (SEM) image of the black phosphorus nanosheet film in Comparative Example 2, which reveals the uneven surface of the black phosphorus nanosheet film.

[0129] Comparative Example 3

[0130] The difference from Example 1 is that tetra-n-butylhexafluorophosphate ammonium is replaced with tetrabutylammonium phosphate.

[0131] (1) Using tetrabutylammonium phosphate as raw material, at room temperature and with N,N dimethylformamide as solvent, prepare a tetrabutylammonium hexafluorophosphate solution of 38.7 mg / 10 mL, which is the electrolyte.

[0132] (2) Place 10 ml of the electrolyte in a 50 ml beaker, then use black phosphorus crystals as the cathode and a platinum electrode as the anode. The distance between the two electrodes is 2 cm. Control the current density at 0.004 A / cm² and react for 3 hours.

[0133] (3) After repeatedly washing the precipitate obtained after the reaction with N,N dimethylformamide and isopropanol, black phosphorus nanosheets were obtained.

[0134] (4) Disperse black phosphorus nanosheets at 25°C in isopropanol with an oxygen concentration of less than 0.1 ppm and sonicate for 20 minutes to obtain a black phosphorus nanosheet dispersion with a concentration of 1.5 mg / mL.

[0135] (5) In a glove box at 25°C, the black phosphorus nano-dispersion was dripped dropwise at a rate of 10 μL onto a flexible polyethylene terephthalate interdigitated electrode, and dried in the glove box at 25°C until the electrode was conductive, thus obtaining an interdigitated electrode coated with a black phosphorus nanosheet film. Subsequently, a 20 μm thick polydimethylsiloxane film was encapsulated on the electrode surface using electrostatic force to obtain a flexible interdigitated electrode based on a black phosphorus nanosheet film.

[0136] (6) First, the black phosphorus nanosheet thin film interdigitated electrode prepared in step (5) was connected to the SJ Shenju AF250FF46-2 wire using TED PELLA-JY16031 silver paste from the United States. Then, the flexible electrode was connected to the Shanghai Chenhua CHI660E electrochemical workstation through the same wire to form a sensor device (flexible sensor device) based on black phosphorus nanosheet thin film. The sensor response to different breathing frequencies was then tested at a constant voltage of +10V.

[0137] Figure 18 The diagram shows the respiratory sensing performance of the sensor based on black phosphorus nanosheet film in Comparative Example 3. Respiratory sensing test results show that the sensor lacks distinguishability under different breathing modes, including deep breathing, normal breathing, and rapid breathing. Photoelectric sensing test results show that the sensor based on black phosphorus nanosheet film can respond in a wide wavelength range of 470-940 nm under the same light intensity (4 mW). Pressure sensing test results show that the sensor can exhibit a current response proportional to tensile strain, but both photoelectric and pressure responses are less than those in Example 1. Furthermore, the surface of the black phosphorus nanosheets is uneven and has numerous defects.

Claims

1. A multifunctional sensor for different respiratory rates, photoelectric effects, and pressure, characterized in that, An interdigitated electrode modified with black phosphorus is disclosed. The black phosphorus-modified interdigitated electrode comprises an interdigitated electrode substrate and a black phosphorus nanosheet film disposed on the interdigitated electrode substrate. The interdigitated electrode substrate is a flexible polyethylene terephthalate interdigitated electrode, and the black phosphorus nanosheet film comprises black phosphorus nanosheets. The preparation method of the black phosphorus nanosheets includes the following steps: Step 1: Prepare the electrolyte, including adding tetrabutylammonium hexafluorophosphate to an organic solvent to obtain the electrolyte; Step 2, electrochemical cathode stripping, includes: immersing the anode and cathode in the electrolyte, applying a direct current, and reacting to obtain a precipitate, namely black phosphorus nanosheets, wherein the current density is 0.001-0.01 A / cm², and the reaction time is 1-3 hours; The cathode comprises black phosphorus; The method for preparing the black phosphorus-modified interdigitated electrode includes the following steps: (1) Black phosphorus nanosheets were dispersed in an alcohol solvent to obtain a black phosphorus nanosheet dispersion; (2) The black phosphorus nanosheet dispersion is dropped onto the interdigitated electrode substrate, dried to form a film, and then surface encapsulated to obtain an interdigitated electrode based on a black phosphorus nanosheet film.

2. The multifunctional sensor according to claim 1, characterized in that, The tetrabutylammonium hexafluorophosphate is tetra-n-butylammonium hexafluorophosphate; and / or the organic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, N,N-diethylformamide, and N,N-dimethylacetamide.

3. The multifunctional sensor according to claim 2, characterized in that, The organic solvent is N,N-dimethylformamide.

4. The multifunctional sensor according to any one of claims 1-3, characterized in that, The concentration of tetrabutylammonium hexafluorophosphate in the electrolyte is 10-50 mg / 10 mL.

5. The multifunctional sensor according to claim 4, characterized in that, The concentration of tetrabutylammonium hexafluorophosphate in the electrolyte is 10-40 mg / 10 mL.

6. The multifunctional sensor according to claim 5, characterized in that, The concentration of tetrabutylammonium hexafluorophosphate in the electrolyte is 10~38.7 mg / 10 mL.

7. The multifunctional sensor according to any one of claims 1-3, characterized in that, The electrolyte preparation in step 1 is carried out at 20-35℃.

8. The multifunctional sensor according to claim 7, characterized in that, The electrolyte preparation in step 1 is carried out at 20-25℃.

9. The multifunctional sensor according to any one of claims 1-3, characterized in that, The black phosphorus is black phosphorus crystal; and / or the anode comprises platinum.

10. The multifunctional sensor according to claim 9, characterized in that, The anode is a platinum electrode.

11. The multifunctional sensor according to any one of claims 1-3, characterized in that, The distance between the anode and the cathode in step 2 is 0.5-3 cm.

12. The multifunctional sensor according to claim 11, characterized in that, The distance between the anode and the cathode in step 2 is 1-2 cm.

13. The multifunctional sensor according to any one of claims 1-3, characterized in that, Step 2 also includes washing the precipitate.

14. The multifunctional sensor according to claim 13, characterized in that, The solvent used for washing includes at least one of isopropanol and N,N-dimethylformamide.

15. The multifunctional sensor according to any one of claims 1-3, characterized in that, The black phosphorus nanosheets have a lateral dimension of 1-40 μm and a thickness of 1-30 nanometers.

16. The multifunctional sensor according to claim 15, characterized in that, The black phosphorus nanosheets have a lateral dimension of 1-20 μm and a thickness of 1-10 nanometers.

17. The multifunctional sensor according to any one of claims 1-3, characterized in that, The alcohol solvent is selected from at least one of isopropanol, ethanol, and butanol, and / or the concentration of the black phosphorus nanosheet dispersion is 1.0-2.0 mg / mL, and / or the surface encapsulation is a polydimethylsiloxane film.

18. The multifunctional sensor according to claim 17, characterized in that, The oxygen concentration in the alcohol solvent is less than 0.1 ppm, and / or the thickness of the polydimethylsiloxane film is 10-30 micrometers.

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