A TiO2 nanojungle sensor chip modified with a strongly interconnected hybrid layer via self-driven assembly, its preparation and application

Abstract

The present invention belongs to the field of gas sensing technology, and discloses a TiO2 nano-forest sensor chip modified by a strongly interconnected hybrid layer assembled by self-driven means, as well as its preparation and application. The sensor chip is a composite material of a highly conductive spacing-type titanium dioxide nano-forest array modified by a strongly interconnected hybrid layer, and comprises the following steps: preparing a spacing-type titanium dioxide nanotube array; preparing a highly conductive titanium dioxide nanomaterial; preparing an electrolyte containing polypyrrole and molybdenum salt; and preparing a titanium dioxide nanotube array modified by self-driven assembly of polypyrrole and molybdenum oxide nanoparticles. Using a large spacing titanium dioxide nano-forest array as a support and electron collector for the NO2 sensor chip provides sufficient paths and more reaction sites for the flow of NO2 gas; in addition, the modified strongly interconnected polypyrrole and molybdenum oxide hybrid nanoparticles can promote the transport of carriers, increase the number of electrons participating in the sensing reaction, and ultimately achieve high-sensitivity detection of NO2 at room temperature.

Description

Technical Field

[0001] The present invention relates to the field of gas sensing technology, and in particular to a TiO2 nano-jungle sensing chip modified with a strongly interconnected hybrid layer assembled by self-driven assembly, as well as its preparation and application. Background Art

[0002] With the rapid development of industrial technology, air quality issues have become a focus of great concern in the scientific community. Nitrogen dioxide (NO2), as a harmful gas, is not only the main source of photochemical smog, acid rain and ozone, but when its concentration exceeds 1 ppm, it can also cause permanent damage to the human respiratory system and may increase the risk of asthma, chronic obstructive pulmonary disease (COPD) and cardiovascular disease. In addition, NO2 can also be used as an exhaled breath marker for patients with lung tissue infections and gastrointestinal disorders, and its concentration is usually in the ppb range. Therefore, the development of an efficient NO2 gas sensor that can achieve ultra-high sensitivity room temperature detection of NO2 has great scientific significance and application value for both environmental monitoring and clinical medicine.

[0003] Currently, NO2 is mainly detected by gas chromatography (mass spectrometry), laser spectroscopy and gas sensors. Gas chromatography and laser spectroscopy are generally not suitable for daily environments due to their high cost, complex operation and large equipment. In contrast, gas sensors are widely used in flammable and explosive environments, breath analysis and environmental monitoring due to their small size, low cost and easy operation. However, gas sensors on the market have limitations in the accuracy and response speed of low-concentration (ppb level) detection, and most of them need to operate at high temperatures to ensure sensitivity and selectivity, which increases energy consumption and limits their applicability in specific environments.

[0004] The gas sensing mechanism of metal oxide semiconductor nanomaterials is primarily based on surface chemical reactions between target gases and oxygen molecules adsorbed on the material's surface. Due to their unique physical and chemical sensitivity in gas adsorption and reactivity, they offer highly sensitive and fast-response sensing solutions that accurately reflect environmental changes. Titanium dioxide (TiO2) has garnered widespread attention due to its non-toxicity, high chemical stability, and excellent electron transport and photoelectric conversion properties. Numerous TiO2 nanostructures with large surface areas have been used to enhance gas sensing performance. These structures increase the number of surface active sites, making them highly sensitive to changes in the external atmospheric environment. However, unmodified interspaced TiO2 nanotubes (NTs) still present several challenges when used for gas detection, including slow response and recovery times; poor gas selectivity, making it difficult to accurately identify target gases in a variety of gas environments; and high detection temperatures.

[0005] Based on the above content, it is an urgent problem to prepare a spacing-type titanium dioxide nanotube sensor chip that is conducive to NO2 gas diffusion and to precisely control its structure and surface properties to improve the response recovery speed, reduce the operating temperature and improve the sensitivity. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of existing technologies by providing a TiO2 nanojungle sensor chip modified with a strongly interconnected hybrid layer assembled through self-driven assembly, as well as its preparation and application. This chip utilizes specific materials and design to achieve high-precision and rapid response detection of NO2 at room temperature, overcoming the low sensitivity, high operational stability, and poor stability of existing gas sensors. It is suitable for industrial emission monitoring and clinical applications.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven assembly, which is a composite material of a highly conductive spacing-type titanium dioxide nano-jungle array modified with a strongly interconnected hybrid layer; the highly conductive spacing-type titanium dioxide nano-jungle array is a nanotube array, and the strongly interconnected hybrid layer is a spherical polypyrrole and molybdenum oxide hybrid nanoparticle.

[0008] The nanotube array consists of spaced titanium dioxide nanotubes grown on a substrate. The nanotubes have a diameter of 240 to 260 nm, a length of 3 to 5 μm, and a spacing of 300 to 400 nm between the nanotubes. The spacing of the highly conductive, spaced titanium dioxide nanotube array optimizes gas diffusion paths, reduces detection time, and improves response speed.

[0009] The titanium in the nanotube array exists in the form of trivalent titanium and tetravalent titanium, forming Ti 3+ (O vacancy) defects, the conductivity of nanotubes is as high as 10 3 ~10 4 Ω.

[0010] The spherical polypyrrole and molybdenum oxide form a molybdenum-nitrogen covalent bond to achieve strong interconnection. The self-driven assembly is that the molybdenum-nitrogen covalent bond guides the spherical polypyrrole and molybdenum oxide to spontaneously assemble into hybrid nanoparticles. The spherical polypyrrole and molybdenum oxide hybrid nanoparticles are evenly distributed on the inner side, outer side and top of the titanium dioxide nanotube wall.

[0011] A method for preparing a TiO2 nano-jungle sensor chip comprises the following steps:

[0012] Step 1: Preparation of spaced-spaced anatase-phase titanium dioxide nanotube arrays:

[0013] Step 1.1, preparing a spaced titanium dioxide nanotube array by an anodic oxidation method, using a pure titanium sheet as the anode and a platinum sheet as the cathode. The electrolyte used is a mixed solution of NH4F, deionized water, and triethylene glycol, wherein the volume ratio of water to triethylene glycol is 0.01 to 0.08, and the mass fraction of the NH4F in the mixed solution is 0.2 to 1.5%. A constant voltage of 30 to 80 V is applied for 20 to 60 minutes.

[0014] Step 1.2: After cleaning and drying the spaced amorphous titanium dioxide nanotube array formed on the pure titanium sheet, calcining it at 400-500° C. for 1-4 hours to transform it into a spaced anatase titanium dioxide nanotube array;

[0015] Step 2: Preparation of a high-conductivity, spaced-apart titanium dioxide nanotube forest array:

[0016] Step 2.1, using electrochemical reduction method to prepare high conductive spaced titanium dioxide nanotube jungle array; using a three-electrode device, spaced anatase phase titanium dioxide nanotube array as working electrode, platinum sheet as counter electrode, silver / silver chloride electrode as reference electrode, the electrolyte used is a mixed solution of sodium sulfate and deionized water, wherein the sulfate concentration is 0.1 to 1 mol / L, applying a constant voltage of -5 to -1 V, and lasting for 1.5 to 5 minutes, to obtain Ti nanotubes containing 3+ Highly conductive, spaced-spaced TiO2 nanotube jungle arrays with (O vacancy) defects;

[0017] Step 2.2, washing and drying the prepared high-conductivity spaced titanium dioxide nanotube jungle array;

[0018] Step 3: preparing an electrolyte containing polypyrrole and molybdenum salt:

[0019] Step 3.1, uniformly mixing sodium sulfate, sulfuric acid and deionized water to obtain a mixed solution A;

[0020] Step 3.2, adding 0.001-0.06 mmol / L of polypyrrole and 0.0002-0.01 mmol / L of molybdenum salt to the mixed solution A, and stirring until the solution is uniform;

[0021] Step 4: Preparation of self-propelled assembled polypyrrole and molybdenum oxide nanoparticle-modified titanium dioxide nanotube arrays:

[0022] Step 4.1, using the electrolyte prepared in step 3, cyclic voltammetry to self-assemble spherical polypyrrole and molybdenum oxide nanoparticles into a high-conductivity spaced-apart titanium dioxide nanotube jungle array;

[0023] Step 4.2: Clean and dry the highly conductive spaced titanium dioxide nanotube jungle array modified with polypyrrole and molybdenum oxide nanoparticles.

[0024] In step 3.1, the volume ratio of sulfuric acid to deionized water is 0.01-0.1%, and the concentration of sodium sulfate is 0.05-1 mmol / L.

[0025] In the step 3.2, the molybdenum salt is ammonium molybdate, sodium molybdate or potassium molybdate.

[0026] In the step 3.2, the polypyrrole is distilled and becomes transparent.

[0027] In the step 4.1, the voltage range of the cyclic voltammetry is -2.5-+2.5 V, the scan rate is 30-240 mV / s, and the number of scans is 2-30 times.

[0028] The invention discloses an application of a TiO2 nano-jungle sensor chip. The TiO2 nano-jungle sensor chip is used for NO2 detection, has high sensitivity, a detection temperature of 15-30°C, and a detection limit as low as 0-10ppb. The chip is used for respiratory gas detection and environmental quality detection.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The method of the present invention is simple to operate, highly controllable, and time-saving;

[0031] 2. The present invention uses a large-pitch titanium dioxide nano-forest array as the support and electron collector of the NO2 sensor chip, providing sufficient paths and more reaction sites for the flow of NO2 gas;

[0032] 3. The present invention uses strongly interconnected polypyrrole and molybdenum oxide hybrid nanoparticles to promote the transport of carriers, increase the number of electrons participating in the sensing reaction, and ultimately achieve high-sensitivity detection of NO2 at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a physical picture of the sensor chip prepared in Example 1;

[0034] Figure 2 This is a scanning electron microscope (SEM) photograph of the titanium dioxide nanotube composite material prepared in Example 1;

[0035] Figure 3 is the X-ray diffraction (XRD) pattern of the titanium dioxide nanotube composite material prepared in Example 1;

[0036] Figure 4 FT-IR spectrum of the titanium dioxide nanotube composite material prepared in Example 1;

[0037] Figure 5(a)-Figure 5(e) is the X-ray photoelectron spectroscopy (XPS) of the titanium dioxide nanotube composite material prepared in Example 1;

[0038] Figure 6 This is the dynamic response curve of the sensor chip in Example 1 detecting NO2 in the ppb range;

[0039] Figure 7 This is a calculation diagram of the detection limit of NO2 by the sensor chip of Example 1. DETAILED DESCRIPTION

[0040] Example 1

[0041] A TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven means is a composite material of a highly conductive spaced titanium dioxide nano-jungle array modified with a strongly interconnected hybrid layer; the highly conductive spaced titanium dioxide nano-jungle array is a nanotube array, and the strongly interconnected hybrid layer is a spherical polypyrrole and molybdenum oxide hybrid nanoparticle.

[0042] The nanotube array consists of spaced titanium dioxide nanotubes grown on a substrate. The nanotubes have a diameter of 240 to 260 nm, a length of 3 to 5 μm, and a spacing of 300 to 400 nm between the nanotubes. The spacing of the highly conductive, spaced titanium dioxide nanotube array optimizes gas diffusion paths, reduces detection time, and improves response speed.

[0043] The titanium in the nanotube array exists in the form of trivalent titanium and tetravalent titanium, forming Ti 3+ (O vacancy) defect, the conductivity of the nanotube is 4×10 4 Ω.

[0044] The spherical polypyrrole and molybdenum oxide form a molybdenum-nitrogen covalent bond to achieve strong interconnection. The self-driven assembly is that the molybdenum-nitrogen covalent bond guides the spherical polypyrrole and molybdenum oxide to spontaneously assemble into hybrid nanoparticles. The spherical polypyrrole and molybdenum oxide hybrid nanoparticles are evenly distributed on the inner side, outer side and top of the titanium dioxide nanotube wall.

[0045] The method for preparing the TiO2 nano-jungle sensor chip comprises the following steps:

[0046] Step 1: Preparation of spaced-spaced anatase-phase titanium dioxide nanotube arrays:

[0047] Step 1.1: Prepare a spaced titanium dioxide nanotube array by anodic oxidation, using a pure titanium sheet as the anode and a platinum sheet as the cathode. The electrolyte used is a mixed solution of NH4F, deionized water, and triethylene glycol, wherein the volume ratio of water to triethylene glycol is 0.03 and the mass fraction of NH4F in the mixed solution is 1%. A constant voltage of 60 V is applied for 30 min.

[0048] Step 1.2: After cleaning and drying the spaced amorphous titanium dioxide nanotube arrays formed on the pure titanium sheet, calcining them at 450° C. for 2 h to transform them into spaced anatase titanium dioxide nanotube arrays;

[0049] Step 2: Preparation of a high-conductivity, spaced-apart titanium dioxide nanotube forest array:

[0050] Step 2.1, using electrochemical reduction method to prepare high conductive spaced titanium dioxide nanotube forest array; using a three-electrode device, spaced anatase phase titanium dioxide nanotube array as working electrode, platinum sheet as counter electrode, silver / silver chloride electrode as reference electrode, the electrolyte used is a mixed solution of sodium sulfate and deionized water, wherein the sulfate concentration is 0.2 mol / L, applying a constant voltage of -2 V, lasting for 2 min, to obtain Ti containing 3+ Highly conductive, spaced-spaced TiO2 nanotube jungle arrays with (O vacancy) defects;

[0051] Step 2.2, washing and drying the prepared high-conductivity spaced titanium dioxide nanotube jungle array;

[0052] Step 3: preparing an electrolyte containing polypyrrole and molybdenum salt:

[0053] Step 3.1, uniformly mixing sodium sulfate, sulfuric acid and deionized water to obtain a mixed solution A;

[0054] Step 3.2, add 0.006 mmol / L of polypyrrole and 0.00042 mmol / L of molybdenum salt to the mixed solution A, and stir until the solution is uniform;

[0055] Step 4: Preparation of self-propelled assembled polypyrrole and molybdenum oxide nanoparticle-modified titanium dioxide nanotube arrays:

[0056] Step 4.1, using the electrolyte prepared in step 3, cyclic voltammetry to self-assemble spherical polypyrrole and molybdenum oxide nanoparticles into a high-conductivity spaced-apart titanium dioxide nanotube jungle array;

[0057] Step 4.2: Clean and dry the highly conductive spaced titanium dioxide nanotube jungle array modified with polypyrrole and molybdenum oxide nanoparticles.

[0058] In step 3.1, the volume ratio of sulfuric acid to deionized water is 0.09%, and the concentration of sodium sulfate is 0.05-0.5 mmol / L.

[0059] In the step 3.2, the molybdenum salt is ammonium molybdate.

[0060] In the step 3.2, the polypyrrole is distilled and becomes transparent.

[0061] In step 4.1, the voltage range of the cyclic voltammetry is -1.5–+2 V, the scan rate is 180 mV / s, and the number of scans is 8 times.

[0062] The TiO2 nano-jungle sensor chip is used for NO2 detection, has high sensitivity, a detection temperature of 25°C, a detection limit of 0.15ppb, and is used for respiratory gas detection and environmental quality detection.

[0063] The titanium dioxide nanotube composite material sensor chip obtained in Example 1 is as follows Figure 1 The results are shown in Figure 2, and the scanning electron microscope (SEM), X-ray diffraction (XRD), infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the product. Figure 2 、 Figure 3 、 Figure 4 , Figure 5(a), Figure 5(b), Figure 5(c), Figure 5(d), and Figure 5(e). Figure 2 It can be seen from the figure that the diameter of the titanium dioxide nanotubes is 240-260nm, and the spacing between the tubes is 300-400nm, which provides space for the subsequent modification of nanoparticles. In addition, it can be clearly seen from the electron microscope photos that the spherical nanoparticles have been successfully modified to the inner and outer sides of the tube wall and the top of the titanium dioxide nanotubes. Figure 3 It can be seen that the (101), (103), (004), (112), (200), (105), (211), (204), (220) and (301) crystal planes of the anatase phase indicate that the titanium dioxide prepared is anatase phase. It can also be found in the figure that both polypyrrole and molybdenum oxide are amorphous structures. Furthermore, it can be obtained from infrared spectroscopy (FT-IR) ( Figure 4 ), 729cm -1 The characteristic peaks at 1050, 1457 and 1558 cm are attributed to the vibration peaks of O-Mo-O; -1 The characteristic peaks at and are attributed to the stretching vibrations of CH, CN, and C=C in the pyrrole ring, respectively. All of these characteristic peaks indicate that polypyrrole and molybdenum oxide nanoparticles were successfully modified onto titania nanotubes. Furthermore, Figure 5 shows the presence of Ti, O, Mo, N, and C in the titania nanocomposite, indicating that the polypyrrole and molybdenum oxide are connected via a molybdenum-nitrogen bond.

[0064] The NO2 sensing performance of the sensor chip based on titanium dioxide nanotube composite material was tested, and the results are as follows Figure 6 and Figure 7 As shown. Figure 6 The available sensor chip exhibits a sensitive response to trace amounts of NO2 at the ppb level (1-1000ppb). Figure 7 It can be seen that the response of the sensor chip to NO2 is positively correlated with the concentration, with a good linear relationship and a minimum detection limit of 0.15 ppb.

[0065] Example 2

[0066] A TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven means is a composite material of a highly conductive spaced titanium dioxide nano-jungle array modified with a strongly interconnected hybrid layer; the highly conductive spaced titanium dioxide nano-jungle array is a nanotube array, and the strongly interconnected hybrid layer is a spherical polypyrrole and molybdenum oxide hybrid nanoparticle.

[0067] The nanotube array consists of spaced titanium dioxide nanotubes grown on a substrate. The nanotubes have a diameter of 240 to 260 nm, a length of 3 to 5 μm, and a spacing of 300 to 400 nm between the nanotubes. The spacing of the highly conductive, spaced titanium dioxide nanotube array optimizes gas diffusion paths, reduces detection time, and improves response speed.

[0068] The titanium in the nanotube array exists in the form of trivalent titanium and tetravalent titanium, forming Ti 3+ (O vacancy) defect, the conductivity of the nanotube is 8×10 3 Ω.

[0069] The spherical polypyrrole and molybdenum oxide form a molybdenum-nitrogen covalent bond to achieve strong interconnection. The self-driven assembly is that the molybdenum-nitrogen covalent bond guides the spherical polypyrrole and molybdenum oxide to spontaneously assemble into hybrid nanoparticles. The spherical polypyrrole and molybdenum oxide hybrid nanoparticles are evenly distributed on the inner side, outer side and top of the titanium dioxide nanotube wall.

[0070] The method for preparing the TiO2 nano-jungle sensor chip comprises the following steps:

[0071] Step 1: Preparation of spaced-spaced anatase-phase titanium dioxide nanotube arrays:

[0072] Step 1.1: A spaced titanium dioxide nanotube array was prepared by an anodic oxidation method, using a pure titanium sheet as the anode and a platinum sheet as the cathode. The electrolyte used was a mixed solution of NH4F, deionized water, and triethylene glycol, wherein the volume ratio of water to triethylene glycol was 0.05 and the mass fraction of NH4F in the mixed solution was 1.2%. A constant voltage of 60 V was applied for 20 min.

[0073] Step 1.2: After cleaning and drying the spaced amorphous titanium dioxide nanotube arrays formed on the pure titanium sheet, the arrays were calcined at 400° C. for 1.5 h to transform them into spaced anatase titanium dioxide nanotube arrays;

[0074] Step 2: Preparation of a high-conductivity, spaced-apart titanium dioxide nanotube forest array:

[0075] Step 2.1, using electrochemical reduction method to prepare high conductive spaced titanium dioxide nanotube forest array; using a three-electrode device, spaced anatase phase titanium dioxide nanotube array as working electrode, platinum sheet as counter electrode, silver / silver chloride electrode as reference electrode, the electrolyte used is a mixed solution of sodium sulfate and deionized water, wherein the sulfate concentration is 0.1 mol / L, applying a constant voltage of -3 V, lasting for 1 min, to obtain Ti containing 3+ Highly conductive, spaced-spaced TiO2 nanotube jungle arrays with (O vacancy) defects;

[0076] Step 2.2, washing and drying the prepared high-conductivity spaced titanium dioxide nanotube jungle array;

[0077] Step 3, preparing an electrolyte containing polypyrrole and molybdenum salt;

[0078] Step 3.1, uniformly mixing sodium sulfate, sulfuric acid and deionized water to obtain a mixed solution A;

[0079] Step 3.2, add 0.012 mmol / L of polypyrrole and 0.00084 mmol / L of molybdenum salt to the mixed solution A, and stir until the solution is uniform;

[0080] Step 4: Preparation of self-propelled assembled polypyrrole and molybdenum oxide nanoparticle-modified titanium dioxide nanotube arrays:

[0081] Step 4.1, using the electrolyte prepared in step 3, cyclic voltammetry to self-assemble spherical polypyrrole and molybdenum oxide nanoparticles into a high-conductivity spaced-apart titanium dioxide nanotube jungle array;

[0082] Step 4.2: Clean and dry the highly conductive spaced titanium dioxide nanotube jungle array modified with polypyrrole and molybdenum oxide nanoparticles.

[0083] In step 3.1, the volume ratio of sulfuric acid to deionized water is 0.05%, and the concentration of sodium sulfate is 0.1 mmol / L.

[0084] In the step 3.2, the molybdenum salt is sodium molybdate.

[0085] In the step 3.2, the polypyrrole is distilled and becomes transparent.

[0086] In step 4.1, the voltage range of the cyclic voltammetry is -2–+2.5 V, the scan rate is 120 mV / s, and the number of scans is 5.

[0087] The TiO2 nano-jungle sensor chip is used for NO2 detection, has high sensitivity, a detection temperature of 20°C, a detection limit of 4 ppb, and is used for respiratory gas detection and environmental quality detection.

[0088] Example 3

[0089] A TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven means is a composite material of a highly conductive spaced titanium dioxide nano-jungle array modified with a strongly interconnected hybrid layer; the highly conductive spaced titanium dioxide nano-jungle array is a nanotube array, and the strongly interconnected hybrid layer is a spherical polypyrrole and molybdenum oxide hybrid nanoparticle.

[0090] The nanotube array consists of spaced titanium dioxide nanotubes grown on a substrate. The nanotubes have a diameter of 240 to 260 nm, a length of 3 to 5 μm, and a spacing of 300 to 400 nm between the nanotubes. The spacing of the highly conductive, spaced titanium dioxide nanotube array optimizes gas diffusion paths, reduces detection time, and improves response speed.

[0091] The titanium in the nanotube array exists in the form of trivalent titanium and tetravalent titanium, forming Ti 3+ (O vacancy) defect, the conductivity of the nanotube is 2×10 4 Ω.

[0092] The spherical polypyrrole and molybdenum oxide form a molybdenum-nitrogen covalent bond to achieve strong interconnection. The self-driven assembly is that the molybdenum-nitrogen covalent bond guides the spherical polypyrrole and molybdenum oxide to spontaneously assemble into hybrid nanoparticles. The spherical polypyrrole and molybdenum oxide hybrid nanoparticles are evenly distributed on the inner side, outer side and top of the titanium dioxide nanotube wall.

[0093] The method for preparing the TiO2 nano-jungle sensor chip comprises the following steps:

[0094] Step 1: Preparation of spaced-spaced anatase-phase titanium dioxide nanotube arrays:

[0095] Step 1.1: Prepare a spaced titanium dioxide nanotube array by anodic oxidation, using a pure titanium sheet as the anode and a platinum sheet as the cathode. The electrolyte used is a mixed solution of NH4F, deionized water, and triethylene glycol, wherein the volume ratio of water to triethylene glycol is 0.04 and the mass fraction of NH4F in the mixed solution is 0.6%. A constant voltage of 55 V is applied for 40 min.

[0096] Step 1.2: After cleaning and drying the spaced amorphous titanium dioxide nanotube arrays formed on the pure titanium sheet, calcining them at 480° C. for 1 hour to transform them into spaced anatase titanium dioxide nanotube arrays;

[0097] Step 2: Preparation of a high-conductivity, spaced-apart titanium dioxide nanotube forest array:

[0098] Step 2.1, using electrochemical reduction method to prepare high conductive spaced titanium dioxide nanotube forest array; using a three-electrode device, spaced anatase phase titanium dioxide nanotube array as working electrode, platinum sheet as counter electrode, silver / silver chloride electrode as reference electrode, the electrolyte used is a mixed solution of sodium sulfate and deionized water, wherein the sulfate concentration is 0.2 mol / L, applying a constant voltage of -5 V for 3 min, obtaining Ti nanotubes containing 3+ Highly conductive, spaced-spaced TiO2 nanotube jungle arrays with (O vacancy) defects;

[0099] Step 2.2, washing and drying the prepared high-conductivity spaced titanium dioxide nanotube jungle array;

[0100] Step 3: preparing an electrolyte containing polypyrrole and molybdenum salt:

[0101] Step 3.1, uniformly mixing sodium sulfate, sulfuric acid and deionized water to obtain a mixed solution A;

[0102] Step 3.2: Add 0.03 mmol / L of polypyrrole and 0.0042 mmol / L of molybdenum salt to the mixed solution A and stir until the solution is uniform.

[0103] Step 4: Preparation of self-propelled assembled polypyrrole and molybdenum oxide nanoparticle-modified titanium dioxide nanotube arrays:

[0104] Step 4.1, using the electrolyte prepared in step 3, cyclic voltammetry to self-assemble spherical polypyrrole and molybdenum oxide nanoparticles into a high-conductivity spaced-apart titanium dioxide nanotube jungle array;

[0105] Step 4.2: Clean and dry the highly conductive spaced titanium dioxide nanotube jungle array modified with polypyrrole and molybdenum oxide nanoparticles.

[0106] In step 3.1, the volume ratio of sulfuric acid to deionized water is 0.02%, and the concentration of sodium sulfate is 0.5 mmol / L.

[0107] In the step 3.2, the molybdenum salt is potassium molybdate.

[0108] In the step 3.2, the polypyrrole is distilled and becomes transparent.

[0109] In step 4.1, the voltage range of the cyclic voltammetry is -1.8–+1.8 V, the scan rate is 260 mV / s, and the number of scans is 10.

[0110] The TiO2 nano-jungle sensor chip is used for NO2 detection, has high sensitivity, a detection temperature of 22°C, and a detection limit of 6 ppb, and is used for respiratory gas detection and environmental quality detection.

[0111] Comparative Example 1

[0112] A TiO2 nano-forest sensing chip is a high-conductivity spacing-type titanium dioxide nano-forest array, wherein the high-conductivity spacing-type titanium dioxide nano-forest array is a nanotube array.

[0113] The nanotube array is titanium dioxide nanotubes grown on a substrate with a certain distance between them. The diameter of the titanium dioxide nanotubes is 240-260 nm, the length is 3-5 μm, and the distance between the titanium dioxide nanotubes is 300-400 nm.

[0114] The titanium in the nanotube array exists in the form of trivalent titanium and tetravalent titanium, forming Ti 3+ (O vacancy) defect, the conductivity of the nanotube is 4×10 4 Ω.

[0115] The method for preparing the TiO2 nano-jungle sensor chip comprises the following steps:

[0116] Step 1: Preparation of spaced-spaced anatase-phase titanium dioxide nanotube arrays:

[0117] Step 1.1: Prepare a spaced titanium dioxide nanotube array by anodic oxidation, using a pure titanium sheet as the anode and a platinum sheet as the cathode. The electrolyte used is a mixed solution of NH4F, deionized water, and triethylene glycol, wherein the volume ratio of water to triethylene glycol is 0.03 and the mass fraction of NH4F in the mixed solution is 1%. A constant voltage of 60 V is applied for 30 min.

[0118] Step 1.2: After cleaning and drying the spaced amorphous titanium dioxide nanotube arrays formed on the pure titanium sheet, calcining them at 450° C. for 2 h to transform them into spaced anatase titanium dioxide nanotube arrays;

[0119] Step 2: Preparation of a high-conductivity, spaced-apart titanium dioxide nanotube forest array:

[0120] Step 2.1, using electrochemical reduction method to prepare high conductive spaced titanium dioxide nanotube forest array; using a three-electrode device, spaced anatase phase titanium dioxide nanotube array as working electrode, platinum sheet as counter electrode, silver / silver chloride electrode as reference electrode, the electrolyte used is a mixed solution of sodium sulfate and deionized water, wherein the sulfate concentration is 0.2 mol / L, applying a constant voltage of -2 V, lasting for 2 min, to obtain Ti containing 3+ Highly conductive, spaced-spaced TiO2 nanotube jungle arrays with (O vacancy) defects;

[0121] Step 2.2, washing and drying the prepared high-conductivity spaced titanium dioxide nanotube jungle array;

[0122] The TiO2 nano-jungle sensor chip used for NO2 detection has low sensitivity, a detection temperature of 25°C, and a detection limit of 5 ppm, which cannot meet the requirements of breath gas detection and environmental quality monitoring. To achieve ppb-level (10 ppb) NO2 detection, the sensor chip requires a detection temperature of up to 200°C.

[0123] Comparative Example 2

[0124] A TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven means is a composite material of a spacing-type titanium dioxide nano-jungle array modified with a strongly interconnected hybrid layer; the spacing-type titanium dioxide nano-jungle array is a nanotube array, and the strongly interconnected hybrid layer is a spherical polypyrrole and molybdenum oxide hybrid nanoparticle.

[0125] The nanotube array is titanium dioxide nanotubes grown on a substrate with a certain distance between them. The diameter of the titanium dioxide nanotubes is 240-260 nm, the length is 3-5 μm, and the distance between the titanium dioxide nanotubes is 300-400 nm.

[0126] The titanium in the nanotube array exists in the form of tetravalent titanium, without Ti 3+ (O vacancy) defect, the conductivity of the nanotube is 7×10 7 Ω.

[0127] The spherical polypyrrole and molybdenum oxide form a molybdenum-nitrogen covalent bond to achieve strong interconnection. The self-driven assembly is that the molybdenum-nitrogen covalent bond guides the spherical polypyrrole and molybdenum oxide to spontaneously assemble into hybrid nanoparticles. The spherical polypyrrole and molybdenum oxide hybrid nanoparticles are evenly distributed on the inner side, outer side and top of the titanium dioxide nanotube wall.

[0128] The method for preparing the TiO2 nano-jungle sensor chip comprises the following steps:

[0129] Step 1: Preparation of spaced-spaced anatase-phase titanium dioxide nanotube arrays:

[0130] Step 1.1: A spaced titanium dioxide nanotube array was prepared by an anodic oxidation method, using a pure titanium sheet as the anode and a platinum sheet as the cathode. The electrolyte used was a mixed solution of NH4F, deionized water, and triethylene glycol, wherein the volume ratio of water to triethylene glycol was 0.03 and the mass fraction of NH4F in the mixed solution was 1%. A constant voltage of 60 V was applied for 30 min.

[0131] Step 1.2: After cleaning and drying the spaced amorphous titanium dioxide nanotube arrays formed on the pure titanium sheet, calcining them at 450° C. for 2 h to transform them into spaced anatase titanium dioxide nanotube arrays;

[0132] Step 2: preparing an electrolyte containing polypyrrole and molybdenum salt:

[0133] Step 2.1, uniformly mixing sodium sulfate, sulfuric acid and deionized water to obtain a mixed solution A;

[0134] Step 2.2: Add 0.006 mmol / L of polypyrrole and 0.00042 mmol / L of molybdenum salt to mixed solution A and stir until the solution is uniform.

[0135] Step 3: Preparation of self-assembled polypyrrole and molybdenum oxide nanoparticle-modified titanium dioxide nanotube arrays:

[0136] Step 3.1, using the electrolyte prepared in step 2, cyclic voltammetry is used to self-assemble spherical polypyrrole and molybdenum oxide nanoparticles into a high-conductivity spaced-apart titanium dioxide nanotube jungle array;

[0137] Step 3.2: Clean and dry the highly conductive spaced titanium dioxide nanotube jungle array modified with polypyrrole and molybdenum oxide nanoparticles.

[0138] In step 2.1, the volume ratio of sulfuric acid to deionized water is 0.09%, and the concentration of sodium sulfate is 0.5 mmol / L.

[0139] In the step 2.2, the molybdenum salt is ammonium molybdate.

[0140] In the step 2.2, the polypyrrole is distilled and becomes transparent.

[0141] In the step 3.1, the voltage range of the cyclic voltammetry is -1.5-+2 V, the scan rate is 180 mV / s, and the number of scans is 8 times.

[0142] The TiO2 nano-jungle sensor chip used for NO2 detection has low sensitivity, a detection temperature of 25°C, and a detection limit of 2 ppm, which cannot meet the requirements of breath gas detection and environmental quality monitoring. To achieve ppb-level (10 ppb) NO2 detection, the sensor chip requires a detection temperature of up to 150°C.

[0143] Comparative Example 3

[0144] A TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven means is a composite material of a spacing-type titanium dioxide nano-jungle array modified with a strongly interconnected hybrid layer; the spacing-type titanium dioxide nano-jungle array is a nanotube array, and the strongly interconnected hybrid layer is a spherical polypyrrole and molybdenum oxide hybrid nanoparticle.

[0145] A TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven driving, characterized in that the sensor chip is a composite material of a highly conductive spaced titanium dioxide nano-jungle array modified with a strongly interconnected hybrid layer; the highly conductive spaced titanium dioxide nano-jungle array is a nanotube array, and the strongly interconnected hybrid layer is spherical polypyrrole and molybdenum oxide hybrid nanoparticles.

[0146] The spacing type high-conductivity titanium dioxide nanotube array is titanium dioxide nanotubes with spacing grown on a substrate. The diameter of the titanium dioxide nanotubes is 240-260 nm, the length is 3-5 μm, and the spacing between the tubes is 300-400 nm.

[0147] The titanium in the spacing type high conductive titanium dioxide nanotube array exists in the form of trivalent titanium and tetravalent titanium, forming Ti 3+ (O vacancy) defect, the conductivity of the tube is as high as 10 3 ~10 4 Ω.

[0148] A molybdenum-nitrogen covalent bond is formed between the polypyrrole and the molybdenum oxide to achieve strong interconnection. The self-driven assembly is that the molybdenum-nitrogen covalent bond guides the polypyrrole and molybdenum oxide to spontaneously assemble into composite nanoparticles. The polypyrrole and molybdenum oxide nanoparticles are evenly distributed on the inner side, outer side and top of the titanium dioxide nanotube wall.

[0149] The method for preparing the sensor chip comprises the following steps:

[0150] Step 1: Prepare a spaced titanium dioxide nanotube array:

[0151] Step 1.1: Prepare a spaced titanium dioxide nanotube array by anodic oxidation, using a pure titanium sheet as the anode and a platinum sheet as the cathode. The electrolyte used is a mixed solution of NH4F, deionized water, and triethylene glycol, wherein the volume ratio of water to triethylene glycol is 0.03 and the mass fraction of NH4F in the mixed solution is 1%. A constant voltage of 60 V is applied for 30 min.

[0152] Step 1.2: After cleaning and drying the spaced amorphous titanium dioxide nanotube array generated on the pure titanium sheet, the array was calcined at 450° C. for 2 h to transform it into a spaced anatase phase titanium dioxide nanotube array.

[0153] Step 2: Preparation of high-conductivity spaced titanium dioxide nanotube arrays:

[0154] Step 2.1, a high-conductivity spaced titanium dioxide nanotube array was prepared by electrochemical reduction method, using a three-electrode device, wherein the spaced titanium dioxide nanotube array was used as the working electrode, the platinum sheet was used as the counter electrode, and the silver / silver chloride electrode was used as the reference electrode. The electrolyte used was a mixed solution of sodium sulfate and deionized water, wherein the sulfate concentration was 0.2 mol / L. A constant voltage of -2 V was applied for 2 min to obtain a TiO2 nanotube array. 3+ Highly conductive spaced titanium dioxide nanotube arrays with (O vacancy) defects;

[0155] Step 2.2: Clean and dry the prepared high-conductivity spaced titanium dioxide nanotube array.

[0156] Step 3: preparing an electrolyte containing polypyrrole and molybdenum salt:

[0157] Step 3.1, uniformly mixing sodium sulfate, sulfuric acid and deionized water to obtain a mixed solution A;

[0158] Step 3.2: Add 0.1 mmol / L of polypyrrole and 0.1 mmol / L of molybdenum salt to the mixed solution A and stir vigorously until the solution is uniform.

[0159] Step 4: Preparation of self-propelled assembled polypyrrole and molybdenum oxide nanoparticle-modified titanium dioxide nanotube arrays:

[0160] Step 4.1, using the electrolyte prepared in step 3, cyclic voltammetry to self-assemble spherical polypyrrole and molybdenum oxide nanoparticles onto titanium dioxide nanotube arrays;

[0161] Step 4.2: Clean and dry the titanium dioxide nanotube array modified with polypyrrole and molybdenum oxide nanoparticles.

[0162] In step 3.1, the volume ratio of sulfuric acid to deionized water in the electrolyte is 0.09%, and the concentration of sodium sulfate is 0.5 mmol / L.

[0163] In the step 3.2, the molybdenum salt includes ammonium molybdate.

[0164] In the step 3.2, the polypyrrole is distilled and becomes transparent.

[0165] In step 4.1, the voltage range of the cyclic voltammetry is -2.5-+2.5 V, the scan rate is 5 mV / s, and the number of scans is 50.

[0166] The sensor chip used for NO2 detection has low sensitivity, a detection temperature of 25°C, and a detection limit of up to 10 ppm, which cannot meet the requirements of breath gas detection and environmental quality monitoring. To achieve ppb-level (10 ppb) NO2 detection, the sensor chip requires a detection temperature of up to 220°C.

[0167] The following are the detection limits of the TiO2 nano-jungle sensor chips obtained in each embodiment and comparative example.

[0168] Example 1: 0.15 ppb; Example 2: 4 ppb; Example 3: 6 ppb; Comparative Example 1: 5 ppm; Comparative Example 2: 2 ppm; Comparative Example 3: 10 ppm.

[0169] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above preferred solutions can be freely combined and superimposed.

[0170] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven assembly, characterized in that: The TiO2 nano-jungle sensor chip is a composite material of a highly conductive spacing-type titanium dioxide nano-jungle array modified with a strongly interconnected hybrid layer; the highly conductive spacing-type titanium dioxide nano-jungle array is a nanotube array, and the strongly interconnected hybrid layer is a spherical polypyrrole and molybdenum oxide hybrid nanoparticle; a molybdenum-nitrogen covalent bond is formed between the spherical polypyrrole and the molybdenum oxide to achieve strong interconnection, and the self-driven assembly is a molybdenum-nitrogen covalent bond guiding the spherical polypyrrole and molybdenum oxide to spontaneously assemble into hybrid nanoparticles, and the spherical polypyrrole and molybdenum oxide hybrid nanoparticles are evenly distributed on the inner side, outer side and top of the titanium dioxide nanotube wall.

2. The TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven assembly according to claim 1, characterized in that: The nanotube array is titanium dioxide nanotubes grown on a substrate with a certain spacing. The diameter of the titanium dioxide nanotubes is 240-260 nm, the length is 3-5 μm, and the spacing between the titanium dioxide nanotubes is 300-400 nm.

3. The TiO2 nano-jungle sensor chip modified with a strongly interconnected hybrid layer assembled by self-driven assembly according to claim 1, characterized in that: The titanium in the nanotube array exists in the form of trivalent titanium and tetravalent titanium, forming Ti 3+ O vacancy defects, the conductivity of the nanotube is as high as 10 3 ~10 4 Ω.

4. A method for preparing the TiO2 nano-jungle sensor chip according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Preparation of spaced-spaced anatase-phase titanium dioxide nanotube arrays: Step 1.1, preparing a spaced titanium dioxide nanotube array by an anodic oxidation method, using a pure titanium sheet as the anode and a platinum sheet as the cathode. The electrolyte used is a mixed solution of NH4F, deionized water, and triethylene glycol, wherein the volume ratio of water to triethylene glycol is 0.01 to 0.08, and the mass fraction of the NH4F in the mixed solution is 0.2 to 1.5%. A constant voltage of 30 to 80 V is applied for 20 to 60 minutes. Step 1.2: After cleaning and drying the spaced amorphous titanium dioxide nanotube array formed on the pure titanium sheet, calcining it at 400-500° C. for 1-4 hours to transform it into a spaced anatase titanium dioxide nanotube array; Step 2: Preparation of a high-conductivity, spaced-apart titanium dioxide nanotube forest array: Step 2.1, using electrochemical reduction method to prepare high conductive spaced titanium dioxide nanotube jungle array; using a three-electrode device, spaced anatase phase titanium dioxide nanotube array as working electrode, platinum sheet as counter electrode, silver / silver chloride electrode as reference electrode, the electrolyte used is a mixed solution of sodium sulfate and deionized water, wherein the sulfate concentration is 0.1 to 1 mol / L, applying a constant voltage of -5 to -1 V, lasting for 1.5 to 5 minutes, to obtain Ti containing 3+ Highly conductive, spaced-spaced TiO2 nanotube jungle arrays with (O vacancy) defects; Step 2.2, washing and drying the prepared high-conductivity spaced titanium dioxide nanotube jungle array; Step 3: preparing an electrolyte containing polypyrrole and molybdenum salt: Step 3.1, uniformly mixing sodium sulfate, sulfuric acid and deionized water to obtain a mixed solution A; Step 3.2, adding 0.001-0.06 mmol / L of polypyrrole and 0.0002-0.01 mmol / L of molybdenum salt to the mixed solution A, and stirring until the solution is uniform; Step 4: Preparation of self-propelled assembled polypyrrole and molybdenum oxide nanoparticle-modified titanium dioxide nanotube arrays: Step 4.1, using the electrolyte prepared in step 3, cyclic voltammetry to self-assemble spherical polypyrrole and molybdenum oxide nanoparticles into a high-conductivity spaced-apart titanium dioxide nanotube jungle array; Step 4.2: Clean and dry the highly conductive spaced titanium dioxide nanotube jungle array modified with polypyrrole and molybdenum oxide nanoparticles.

5. The preparation method according to claim 4, characterized in that In step 3.1, the volume ratio of sulfuric acid to deionized water is 0.01-0.1%, and the concentration of sodium sulfate is 0.05-1 mmol / L.

6. The preparation method according to claim 4, characterized in that In the step 3.2, the molybdenum salt is ammonium molybdate, sodium molybdate or potassium molybdate.

7. The preparation method according to claim 4, characterized in that In the step 3.2, the polypyrrole is distilled and becomes transparent.

8. The preparation method according to claim 4, characterized in that In the step 4.1, the voltage range of the cyclic voltammetry is -2.5-+2.5 V, the scan rate is 30-240 mV / s, and the number of scans is 2-30 times.

9. An application of the TiO2 nano-jungle sensor chip according to any one of claims 1 to 3 or the TiO2 nano-jungle sensor chip prepared by the preparation method according to any one of claims 4 to 8, characterized in that: The TiO2 nano-jungle sensor chip is used for NO2 detection, has high sensitivity, a detection temperature of 15 to 30°C, and a detection limit as low as 0-10ppb, and is used for respiratory gas detection and environmental quality detection.

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