Single-oriented one-dimensional TiO2 monocrystal nanowire array, its preparation method and application in gas sensing field

Abstract

The application discloses a one-dimensional TiO2 monocrystal nanowire array in single orientation growth, a preparation method thereof and application thereof in the gas sensing field. The preparation method of the one-dimensional TiO2 monocrystal nanowire array comprises the following steps: (1) in-situ synthesizing a TiO2 seed crystal layer on a substrate; and (2) using a hydrothermal method to grow the one-dimensional TiO2 monocrystal nanowire on the TiO2 seed crystal layer to obtain the one-dimensional TiO2 monocrystal nanowire, namely the one-dimensional TiO2 monocrystal nanowire array. The sensing performance of the one-dimensional TiO2 monocrystal nanowire array with different orientations on alcohol (methanol and ethanol) at room temperature is explored, and it is found that the one-dimensional TiO2 monocrystal nanowire array has excellent sensitivity and selectivity, and the detection lower limit can reach the ppb level.

Description

Technical Field

[0001] This invention specifically relates to a one-dimensional TiO2 single-crystal nanowire array grown in a single orientation, its preparation method, and its application in the field of gas sensing. Background Technology

[0002] As a novel and unique nanomaterial assembly structure, single crystalline nanoarrays (SCNAs) with highly preferred orientation have been extensively studied. Among them, one-dimensional (1D) SCNAs (nanowire arrays, nanorod arrays, etc.) have attracted great interest due to their significant advantages in catalysis, energy, and sensing. Because of their efficient electron transport and excellent mass transfer, 1D SCNAs are considered ideal materials for chemical applications and have shown unprecedented potential in various application scenarios such as optoelectronics and sensing.

[0003] The orientation control of 1D SCNAs has a crucial impact on their chemical and physical properties. In some cases, regular horizontal nanoarrays (H-NAs) can provide more electron transport channels and stronger interactions between nanowires and reactants compared to vertical nanoarrays (V-NAs). However, H-NAs must overcome competitive growth from all directions, which involves special growth mechanisms and specific catalyst assistance or surface modification. Therefore, H-NAs are inherently difficult to obtain. In this case, it severely hinders the application of H-NAs in micro / nanoelectronic devices and rigid integrated chips. Therefore, there is an urgent need to develop a rapid and simple method to construct H-NAs with both uniform growth orientation and highly regular arrangement. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A method for preparing a one-dimensional TiO2 single-crystal nanowire array, the method comprising:

[0006] (1) In-situ synthesis of TiO2 seed crystal layer on substrate;

[0007] (2) One-dimensional TiO2 single crystal nanowires are obtained by hydrothermal growth on the TiO2 seed crystal layer, which is a one-dimensional TiO2 single crystal nanowire array.

[0008] According to an embodiment of the present invention, in step (1), the substrate is selected from substrates known in the art, such as sapphire.

[0009] According to an embodiment of the present invention, step (1), the in-situ synthesis of the TiO2 seed layer specifically includes: coating a titanium source onto the substrate surface, and obtaining a TiO2 seed layer on the substrate surface after annealing. Preferably, the coating can be performed using methods known in the art, such as spin coating.

[0010] According to an embodiment of the present invention, the titanium source is provided by an organic solution of a titanium source. Preferably, the titanium source is selected from at least one of tetrabutyl titanate (TBT), isopropyl titanate, titanium tetrachloride, etc. Preferably, the solvent in the organic solution is selected from solvents known in the art, such as ethanol.

[0011] According to an embodiment of the present invention, the concentration of titanium ions in the organic solution of the titanium source is at least greater than 0.02 mol / L, for example, 0.025 mol / L, 0.03 mol / L, 0.04 mol / L, or 0.05 mol / L.

[0012] 0.06 mol / L, 0.07 mol / L, 0.08 mol / L; for example, in the organic solution of the titanium source, the concentration of titanium ions is greater than 0.02 mol / L and less than 0.05 mol / L; for example, in the organic solution of the titanium source, the concentration of titanium ions is greater than 0.05 mol / L, for example, 0.05 mol / L-0.06 mol / L.

[0013] According to an embodiment of the present invention, when the concentration of titanium ions in the organic solution of the titanium source is greater than 0.02 mol / L and less than 0.05 mol / L, the orientation growth of the one-dimensional TiO2 single crystal nanowire is horizontal orientation growth, that is, orientation growth along the plane of the substrate.

[0014] According to an embodiment of the present invention, when the concentration of titanium ions in the organic solution of the titanium source is greater than 0.05 mol / L (e.g., 0.06 mol / L, 0.07 mol / L, 0.08 mol / L), the orientation growth of the one-dimensional TiO2 single crystal nanowire is vertical orientation growth, that is, orientation growth is carried out perpendicular to the plane of the substrate.

[0015] According to an embodiment of the present invention, in step (2), the hydrothermal method specifically includes: placing the TiO2 seed crystal layer in a mixed solution, performing a hydrothermal reaction, and then performing an annealing treatment to obtain the one-dimensional TiO2 single crystal nanowire array.

[0016] Preferably, the conditions for the hydrothermal reaction include: a reaction temperature of 100°C or higher (preferably 100-150°C, for example 120°C); and a reaction time of 1-10 hours (for example 4 hours).

[0017] Preferably, the hydrothermal reaction is carried out in a high-pressure reactor, for example in a stainless steel high-pressure reactor lined with polytetrafluoroethylene.

[0018] Preferably, the mixed solution comprises deionized water, an inorganic acid (such as 37% hydrochloric acid), a saturated salt solution (e.g., saturated sodium chloride solution, potassium chloride solution), and an organic solution of a titanium source. Exemplarily, the mixed solution comprises deionized water, 37% hydrochloric acid, a saturated sodium chloride solution, and an organic solution of a titanium source in a volume ratio of 30:15:10:1. Further, the concentration of the organic solution of the titanium source added to the mixed solution can be the same as or different from that in step (1), preferably the same.

[0019] According to an embodiment of the present invention, after the hydrothermal reaction is completed, the water may optionally be cooled (e.g., naturally cooled), cleaned (e.g., cleaned with deionized water and ethanol respectively), or dried (e.g., dried with nitrogen).

[0020] According to an embodiment of the present invention, the annealing conditions in step (1) or (2) may be the same or different. Preferably, the annealing conditions include annealing at 250-600°C (e.g., 400°C) for 10-120 minutes (e.g., 30 minutes). Further, air or an inert atmosphere can be used as the carrier gas during annealing, and the heating rate during annealing is 1-10° / min, for example, 5° / min.

[0021] The present invention also provides a TiO2 single crystal nanowire, which is prepared by the above method.

[0022] According to an embodiment of the present invention, the length of the TiO2 single crystal nanowire is 10 nm or more, preferably 100 nm or more, for example 200 nm, 300 nm, 500 nm, or 800 nm.

[0023] The present invention also provides a one-dimensional TiO2 single-crystal nanowire array obtained by the above preparation method.

[0024] According to an embodiment of the present invention, the one-dimensional TiO2 single crystal nanowire array includes TiO2 single crystal nanowires and a substrate.

[0025] According to an embodiment of the present invention, the TiO2 single-crystal nanowires in the one-dimensional TiO2 single-crystal nanowire array have a single orientation. Preferably, the orientation is, for example, horizontal or vertical.

[0026] According to an embodiment of the present invention, in the one-dimensional TiO2 single crystal nanowire array, the TiO2 single crystal nanowires are parallel to the substrate, that is, a horizontally oriented TiO2 single crystal nanowire array.

[0027] According to an embodiment of the present invention, in the one-dimensional TiO2 single crystal nanowire array, the TiO2 single crystal nanowires are perpendicular to the substrate, that is, a vertically oriented TiO2 single crystal nanowire array.

[0028] According to an embodiment of the present invention, the length of the TiO2 single crystal nanowire is 10 nm or more, preferably 100 nm or more, for example 200 nm, 300 nm, 500 nm, or 800 nm.

[0029] The present invention also provides the application of the above-mentioned one-dimensional TiO2 single crystal nanowires or one-dimensional TiO2 single crystal nanowire arrays in the field of gas sensing (preferably in the field of room temperature gas sensing), for example, in gas sensors.

[0030] The present invention also provides a gas sensor, the gas sensor comprising the above-mentioned one-dimensional TiO2 single crystal nanowire or the above-mentioned one-dimensional TiO2 single crystal nanowire array.

[0031] According to an embodiment of the present invention, the one-dimensional TiO2 single-crystal nanowire array (e.g., a horizontally oriented TiO2 single-crystal nanowire array) has a response value of more than 500% to ethanol at room temperature, for example, 507 to 2453%.

[0032] According to an embodiment of the present invention, when the one-dimensional TiO2 single crystal nanowire array is a horizontally oriented TiO2 single crystal nanowire array, the theoretical detection limit for ethanol at room temperature is not less than 0.6 ppb.

[0033] According to an embodiment of the present invention, the one-dimensional TiO2 single-crystal nanowire array (e.g., a horizontally oriented TiO2 single-crystal nanowire array) has a response value of more than 300% to methanol at room temperature, for example, 378 to 774%.

[0034] Beneficial effects

[0035] This invention develops a method for preparing one-dimensional TiO2 single-crystal nanowire arrays. Utilizing a surface supersaturation-driven hydrothermal growth mechanism, different growth orientations of the TiO2 nanowires are controlled by adjusting the concentration of the seed crystal solution. For example, one-dimensional titanium dioxide (TiO2) single-crystal nanowire arrays (NAs) can be grown in situ on a sapphire substrate. By changing the concentration of the seed crystal solution, this invention yields single-crystal one-dimensional (1D) TiO2 nanowire arrays with different growth orientations (horizontal and vertical alignment).

[0036] Furthermore, this invention investigated the sensing performance of one-dimensional TiO2 single-crystal nanowire arrays with different orientations for alcohols (methanol, ethanol) at room temperature. It was found that one-dimensional TiO2 single-crystal nanowire arrays exhibit excellent sensitivity and selectivity, with detection limits reaching the ppb level. For example, TiO2-H-NAs showed regular horizontal growth and were able to sensitively detect ethanol at room temperature, demonstrating excellent selectivity and reliable stability. This device not only reduces energy consumption but is also safer and more environmentally friendly. This invention provides a new perspective and approach for the theory and practice of controlling the growth orientation of one-dimensional nanowire arrays, and also offers new ideas for developing high-performance alcohol sensors. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the fabrication process for a one-dimensional TiO2 single-crystal nanowire array.

[0038] Figure 2 The values ​​represent the response values ​​of TiO2 single-crystal nanowire arrays prepared with different seed crystal solution concentrations to 10 ppm (a) ethanol and (b) methanol.

[0039] Figure 3 These are (a) SEM and (b) TEM images of TiO2 single-crystal nanoarrays (TiO2-H-NAs) with a seed crystal concentration of 0.04 M (sample A3). (The insets are high-resolution images and selected area electron diffraction patterns, respectively).

[0040] Figure 4 These are (a) the response-recovery curve and (b) the response-concentration double log linear fitting curve of sample A3 (TiO2-H-NAs) in Example 1 in the range of 2-100 ppm ethanol.

[0041] Figure 5 These are (a) SEM and (b) TEM images of TiO2 single-crystal nanoarrays TiO2-V-NAs (sample A5) with a seed crystal concentration of 0.06 M in Example 2; the insets are high-resolution images and selected area electron diffraction patterns, respectively.

[0042] Figure 6 These are (a) the response-recovery curve and (b) the response-concentration double log linear fitting curve of sample A5 (TiO2-V-NAs) in Example 2 in the range of 2-100 ppm ethanol.

[0043] Figure 7 These are PXRD images of TiO2 single-crystal nanoarrays grown with different seed crystal solution concentrations.

[0044] Figure 8These are SEM images of TiO2 single-crystal nanoarrays with different seed crystal concentrations in Example 3; (a) 0.02M, (b) 0.03M and (c) 0.05M (samples A1, A2 and A4).

[0045] Figure 9 The results are: (a) response-recovery curves of TiO2-H-NAs to methanol at different concentrations (2-100ppm) in Example 4; and (b) log-log linear fit of the methanol response-concentration plot.

[0046] Figure 10 The results in Example 4 are: (a) the response-recovery curves of TiO2-V-NAs to methanol at different concentrations (2-100ppm); and (b) the log-log linear fit of the methanol response-concentration plot. Detailed Implementation

[0047] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0048] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0049] In the following embodiments, the powder X-ray diffraction (PXRD) of the samples was performed using a device equipped with... The morphology of the samples was characterized using a Rigaku SmartLab (Japan). The morphology was determined using a ZEISS Sigma 500 scanning electron microscope and a JEOL JEM-F200 transmission electron microscope.

[0050] In this embodiment, a high-precision sensor integrated testing system was used to test the gas-sensitive sensor performance. The test operating voltage was 5V, and a dynamic gas mixing mode was used to configure the concentration gradient of the test gas (specifically ethanol or methanol), with the gas flow rate controlled at 600 sccm.

[0051] The response value is obtained according to the following formula:

[0052] R = (R a –R g ) / R a ×100%

[0053] The above formula is used for detecting reducing gases; when used for detecting oxidizing gases, the formula for the response value is: R' = (R g '–R a ') / R g'×100%,' where R a = Sensor resistance in air, R g = Sensor resistance when exposed to the target gas.

[0054] All raw materials and chemical reagents used in the production and synthesis of this invention were purchased from Sinopharm Group, and all reagents and pharmaceuticals used were used directly without further purification.

[0055] Example 1

[0056] The preparation of TiO2 nanowire array single crystals involves two processes (such as...) Figure 1 The first step is the preparation of TiO2 seed crystals, and the second step is the hydrothermal growth of TiO2 single-crystal nanowire arrays. The specific preparation process is as follows:

[0057] (a) Preparation of TiO2 seed crystals:

[0058] A spin coater was used to coat a clean sapphire substrate with an ethanol solution containing 0.04M tetrabutyl titanate (TBT) at a speed of 800 rpm for 5 seconds. The substrate was then annealed at 400°C for 30 minutes to form a TiO2 seed layer.

[0059] (b) Hydrothermal growth of TiO2 single-crystal nanowire array

[0060] A sapphire substrate coated with a seed layer was immersed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene. The reactor contained 5 mL of a mixed solution of deionized water, hydrochloric acid (37%), saturated sodium chloride solution, and the TBT ethanol solution from step (a) (volume ratio 30:15:10:1). The reactor was sealed and reacted at 120°C for 4 h. After the reactor cooled naturally, the sapphire substrate was removed and washed three times each with deionized water and ethanol. It was dried with nitrogen and annealed in a tube furnace at 400°C for 0.5 h (using air as the carrier gas, with a heating rate of 5°C / min). The resulting array is sample A3, labeled TiO2-H-NAs.

[0061] At a seed crystal solution concentration of 0.04 M, scanning electron microscopy (SEM) images revealed the morphology of horizontally spread TiO2 nanowires. Figure 3 (a) The (110) plane corresponding to TiO2-H-NAs was clearly observed in the transmission electron microscope (TEM) image. Figure 3 (b)

[0062] (c) Gas sensing performance testing

[0063] At room temperature, the dynamic gas-sensitive response of TiO2-H-NAs to ethanol concentrations of 2ppm, 4ppm, 6ppm, 8ppm, 10ppm, 30ppm, 50ppm, 70ppm, and 100ppm (denoted as 2, 4, 6, 8, 10, 30, 50, 70, and 100) was tested. The results are as follows: Figure 4 As shown in Figure a. Linear fitting is performed on the double logarithmic axis curve ( Figure 4 In section b), the correlation coefficient of the fitted straight line was obtained to be 0.995, further demonstrating a strong linear relationship between the response value and the ethanol concentration. Based on the fitted straight line, the theoretical detection limit of the device for ethanol was calculated to be 0.6 ppb, using 10% of the response value. For example... Figure 4 As shown in Figure a, the coefficient of variation (CV) of the cyclic response of TiO2-H-NAs to 10 ppm ethanol is 1.3%, indicating that the material has good reproducibility. The TiO2-H-NAs gas sensor constructed in this embodiment exhibits a response value of 2453% ( ) to 10 ppm ethanol at room temperature. Figure 2 (a)

[0064] The preparation method of the above TiO2-H-NAs gas sensor device is as follows: the gas sensor prepared by the above TiO2-H-NAs nanoarray is attached to the two ends of the device with silver paste and gold wire is attached to both ends of the device. After aging in an oven at 100℃ for 12 hours, the above test is performed.

[0065] Example 2

[0066] The fabrication of TiO2 single-crystal nanowire arrays involves two processes. The first step is the preparation of TiO2 seed crystals. The second step is the hydrothermal growth of the TiO2 single-crystal nanowire array. The specific fabrication process is as follows:

[0067] (a) Preparation of TiO2 seed crystals:

[0068] A spin coater was used to coat a clean sapphire substrate with an ethanol solution containing 0.06M tetrabutyl titanate (TBT) at a speed of 800 rpm for 5 seconds. The substrate was then annealed at 400°C for 30 minutes to form a TiO2 seed layer.

[0069] (b) Hydrothermal growth of TiO2 single-crystal nanowire array

[0070] A sapphire substrate coated with seed crystals was immersed in a stainless steel high-pressure reactor lined with polytetrafluoroethylene. The reactor contained 5 mL of a mixed solution of deionized water, hydrochloric acid (37%), saturated sodium chloride solution, and the TBT ethanol solution from step a (volume ratio 30:15:10:1). The reactor was sealed and reacted at 120°C for 4 h. After the reactor cooled naturally, the sapphire substrate was removed and washed three times each with deionized water and ethanol. It was dried with nitrogen and annealed in a tube furnace at 400°C for 0.5 h (using air as the carrier gas, with a heating rate of 5°C / min). The resulting array is sample A5, labeled TiO2-V-NAs.

[0071] At a seed crystal solution concentration of 0.06 M, scanning electron microscopy (SEM) images showed TiO2 nanowires growing perpendicular to the substrate, with densely connected array bottoms. Figure 5 (a) The (101) plane corresponding to TiO2-V-NAs was clearly observed in the transmission electron microscope (TEM) image. Figure 5 (b)

[0072] (c) Gas sensing performance testing

[0073] At room temperature, the dynamic gas-sensitive response of TiO2-V-NAs to ethanol concentrations of 2ppm, 4ppm, 6ppm, 8ppm, 10ppm, 30ppm, 50ppm, 70ppm, and 100ppm (denoted as 2, 4, 6, 8, 10, 30, 50, 70, and 100) was tested. The results are as follows: Figure 6 As shown in Figure a. Linear fitting is performed on the double logarithmic axis curve ( Figure 6 In section b), the correlation coefficient of the fitted straight line was obtained to be 0.980, further demonstrating a strong linear relationship between the response value and the ethanol concentration. Based on the fitted straight line, the theoretical detection limit of the device for ethanol was calculated to be 1 ppb, using 10% of the response value. For example... Figure 6 As shown in Figure a, the coefficient of variation (CV) of the cyclic response of TiO2-V-NAs to 10 ppm ethanol is 3.4%, indicating that the material has a certain degree of reproducibility. The constructed TiO2-V-NAs gas sensor device exhibits a response value of 619% ( ) to 10 ppm ethanol at room temperature. Figure 2 (a)

[0074] Example 3

[0075] The fabrication of TiO2 single-crystal nanowire arrays involves two processes. The first step is the preparation of TiO2 seed crystals. The second step is the hydrothermal growth of the TiO2 single-crystal nanowire array. The specific fabrication process is as follows:

[0076] (a) Preparation of TiO2 seed crystals:

[0077] A spin coater was used to coat a cleaned sapphire substrate with ethanol solutions containing 0.02M, 0.03M, and 0.05M tetrabutyl titanate (TBT) at 800 rpm for 5 seconds. The substrate was then annealed at 400°C for 30 minutes to form TiO2 seed layers with different seed concentrations (the corresponding raw material seed concentration is denoted as 0.02M Ti). 4+ 0.03M Ti 4+ and 0.05M Ti 4+ ).

[0078] (b) Hydrothermal growth of TiO2 single-crystal nanowire array

[0079] Sapphire substrates coated with different seed crystal concentrations were immersed in stainless steel high-pressure reactors lined with polytetrafluoroethylene. The reactors contained 5 mL of a mixed solution of deionized water, hydrochloric acid (37%), saturated sodium chloride solution, and the corresponding TBT ethanol solution from step (a) (volume ratio 30:15:10:1). The reactors were sealed and reacted at 120°C for 4 h. After the reactors cooled naturally, the sapphire substrates were removed and washed three times each with deionized water and ethanol. They were dried with nitrogen and annealed in a tube furnace at 400°C for 0.5 h (using air as the carrier gas at a heating rate of 5°C / min). The arrays synthesized using different seed crystal concentrations in the previous step were samples A1, A2, and A4 (corresponding to a raw material seed crystal concentration of 0.02 M Ti). 4+ 0.03M Ti 4 + and 0.05M Ti 4+ ).

[0080] The characteristic peaks of the PXRD of the sample in this embodiment at 27.4° and 56.6° correspond to the (110) and (101) crystal planes, respectively. Figure 7 ).from Figure 8 As can be seen from the SEM images, with the increase of seed crystal solution concentration, the density of the nanoarray changes from sparse to dense, and the growth orientation gradually changes from horizontal growth to vertical growth.

[0081] (c) Gas sensing performance testing

[0082] At room temperature, the gas-sensitive response of a series of samples (A1, A2, and A4) to 10 ppm ethanol was tested, and the results are as follows: Figure 2 As shown in Figure a, it can be seen that as the concentration of the precursor solution increases, the response value of the sample to 10 ppm ethanol also shows a trend of first increasing and then decreasing, namely 0, 507%, and 1557%.

[0083] Example 4

[0084] The fabrication of TiO2 single-crystal nanowire arrays involves two processes. The first step is the preparation of TiO2 seed crystals. The second step is the hydrothermal growth of the TiO2 single-crystal nanowire array (e.g., ...). Figure 1 The specific preparation process is as follows:

[0085] (a) Preparation of TiO2 seed crystals:

[0086] A spin coater was used to coat a cleaned sapphire substrate with ethanol solutions containing 0.02M, 0.03M, 0.04M, 0.05M, and 0.06M tetrabutyl titanate (TBT) at 800 rpm for 5 seconds. The substrate was then annealed at 400°C for 30 minutes to form TiO2 seed layers with different seed concentrations (the corresponding seed concentration in the raw material is denoted as 0.02M Ti). 4+ 0.03M Ti 4+ 0.04M Ti 4+ 0.05M Ti 4+ and 0.06M Ti 4+ ).

[0087] (b) Hydrothermal growth of TiO2 single-crystal nanowire array

[0088] Sapphire substrates coated with different seed crystal concentrations were immersed in stainless steel high-pressure reactors lined with polytetrafluoroethylene. The reactors contained 5 mL of a mixed solution of deionized water, hydrochloric acid (37%), saturated sodium chloride solution, and the corresponding TBT-ethanol solution from step (a) (volume ratio 30:15:10:1). The reactors were sealed and reacted at 120°C for 4 h. After the reactors cooled naturally, the sapphire substrates were removed and washed three times each with deionized water and ethanol. They were dried with nitrogen and annealed in a tube furnace at 400°C for 0.5 h (using air as the carrier gas at a heating rate of 5°C / min). The arrays synthesized using different seed crystal concentrations in the previous step were samples A1-A5 (corresponding to a seed crystal concentration of 0.02 M Ti in the raw materials). 4+ 0.03M Ti 4+ 0.04M Ti 4+ 0.05M Ti 4+ and 0.06M Ti 4+ ), where A3 and A5 are labeled as TiO2-H-NAs and TiO2-V-NAs, respectively.

[0089] (c) Gas sensing performance testing

[0090] At room temperature, the gas-sensitive response of the test series samples (A1-A5) in this embodiment to methanol at a concentration of 10 ppm was as follows: Figure 2As shown in Figure b, the response value of the sample to 10 ppm methanol exhibits a trend of first increasing and then decreasing with the increase of precursor solution concentration, specifically: 0%, 378%, 774%, 693%, and 669%. Specifically, the dynamic gas-sensitive responses of samples A3 and A5 (i.e., TiO2-H-NAs and TiO2-V-NAs) in this embodiment to methanol concentrations of 2 ppm, 4 ppm, 6 ppm, 8 ppm, 10 ppm, 30 ppm, 50 ppm, 70 ppm, and 100 ppm (denoted as 2, 4, 6, 8, 10, 30, 50, 70, and 100) are shown in the figure. Figure 9 a and Figure 10 As shown in Figure a. Based on the fitted straight line of the response, the theoretical detection limits of the device for methanol are calculated to be 12 ppb and 13 ppb, respectively. Figure 9 (e.g., b in middle and b in 10). For example... Figure 9 As shown in Figures 10a and 10a, the coefficients of variation (CVs) of the cyclic response of TiO2-H-NAs and TiO2-V-NAs to 10 ppm methanol are 2.4% and 2.2%, respectively, indicating that the materials have good reproducibility. Therefore, the constructed gas sensor also has a good response to methanol at room temperature.

[0091] The exemplary embodiments of the present invention have been described above. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing one-dimensional TiO2 single-crystal nanowire arrays for the gas sensing field, characterized in that, The preparation method comprises: (1) synthesizing a TiO2 seed layer in situ on a substrate, specifically comprising: coating a titanium source on the surface of the substrate, and obtaining a TiO2 seed layer on the surface of the substrate after annealing treatment; the titanium source is provided by a titanium source organic solution, and the concentration of titanium ions in the titanium source organic solution is greater than 0.02 mol / L and less than 0.05 mol / L; (2) using a hydrothermal method to grow one-dimensional TiO2 single-crystal nanowires on the TiO2 seed layer, wherein the one-dimensional TiO2 single-crystal nanowires are horizontally oriented and grown, i.e., oriented growth along the plane of the substrate, to obtain an array of one-dimensional TiO2 single-crystal nanowires.

2. The production method according to claim 1, characterized by, In step (1), the titanium source is selected from at least one of tetrabutyl titanate, isopropyl titanate, and titanium tetrachloride.

3. The preparation method according to claim 1, characterized in that, In step (2), the hydrothermal method specifically comprises: placing the TiO2 seed layer in a mixed solution, performing a hydrothermal reaction, and then performing annealing treatment to obtain the array of one-dimensional TiO2 single-crystal nanowires; The conditions of the hydrothermal reaction include: a reaction temperature of 100°C or higher, and a reaction time of 1-10 h; And / or, the hydrothermal reaction is performed in a high-pressure reaction kettle.

4. The production method according to claim 3, characterized by, The mixed solution comprises deionized water, an inorganic acid, a saturated salt solution, and a titanium source organic solution.

5. The array of one-dimensional TiO2 single-crystal nanowires obtained by the preparation method according to any one of claims 1-4, wherein the TiO2 single-crystal nanowires in the array have a single orientation.

6. The one-dimensional Ti02 single-crystal nanowire array according to claim 5, wherein The array of one-dimensional TiO2 single-crystal nanowires comprises TiO2 single-crystal nanowires and a substrate.

7. The one-dimensional Ti02 single-crystal nanowire array according to claim 5, wherein The length of the TiO2 single-crystal nanowires is 10 nm or greater.

8. Use of the array of one-dimensional TiO2 single-crystal nanowires according to any one of claims 5-7 in the field of gas sensing.

9. A gas sensor comprising the array of one-dimensional TiO2 single-crystal nanowires according to any one of claims 5-7.

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