Crystalline TiO2@amorphous TiO 2-x Core-shell nanoparticle material and its application in ethanol gas detection

Abstract

The application discloses a kind of crystalline TiO2@amorphous TiO 2‑x The application discloses a kind of core-shell nanoparticle materials and its application in ethanol gas detection.The crystalline TiO2@amorphous TiO 2‑x The application discloses a kind of core-shell nanoparticle materials and its application in ethanol gas detection.The crystalline TiO2@amorphous TiO The application discloses a kind of core-shell nanoparticle materials and its application in ethanol gas detection.The crystalline TiO2@amorphous TiO

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of materials, and particularly relates to a crystalline TiO2@amorphous TiO2 core-shell nanoparticle material for detecting ethanol gas at low temperature 2-x The core-shell nanoparticle material can be applied to ethanol gas detection. BACKGROUND

[0002] Ethanol plays an important role in modern industrial production, pharmaceutical manufacturing, food processing and energy fields. Long-term exposure to ethanol atmosphere can cause damage to human mucous membranes and liver and kidney. High-concentration ethanol can cause explosion and fire when encountering open flames or high-temperature heat sources. Drinking ethanol beverages can cause safety accidents. TiO2-based resistance sensors can be used to detect ethanol molecules. However, the current TiO2-based sensors have defects such as high working temperature and low response. For example, the MoS2 / TiO2 nanoflower material prepared by Sukhwinder Singh et al. (Sensors and Actuators: B. Chemical 350 (2022) 130798) has a response value of only 100% to 500 ppm of ethanol at 300℃. Amorphous TiO 2-x The core-shell nanoparticle material can reduce the activation energy of TiO2-based sensitive materials, thereby effectively reducing the working temperature and improving the response value.

[0003] Invention patent No. 201210475687.5 uses a method of heating a microemulsion solution to prepare smooth spherical amorphous TiO2. Invention patent No. 202111183053.8 uses a solvothermal method to prepare a porous material with mixed distribution of crystalline TiO2 and amorphous TiO2, which has improved electrochromic performance. Currently, no patents and documents have reported a crystalline TiO2@amorphous TiO2 core-shell nanoparticle material for detecting ethanol gas at low temperature. 2-x Preparation of core-shell nanoparticles and their application in the gas sensing field. SUMMARY

[0004] The purpose of the application is to provide a crystalline TiO2@amorphous TiO2 core-shell nanoparticle material for detecting ethanol gas at low temperature. 2-x Core-shell nanoparticle material and its use in the gas sensing field.

[0005] To achieve the above purpose, the crystalline TiO2@amorphous TiO2 core-shell nanoparticle material of the application is prepared by the following steps: 2-x The core-shell nanoparticle can be prepared by the following steps:

[0006] Step 1: Hydrofluoric acid is added to tetrabutyl titanate, and stirring is performed to obtain a white solution; the obtained white solution is transferred into a reaction kettle liner, and is hydrothermally treated at 160-200℃ for 20-28 hours; after the reaction is completed, the reaction product is washed with ethanol and water, and is dried to obtain TiO2 nanosheets with exposed {001} crystal faces;

[0007] Step 2: TiO2 nanosheets with exposed {001} crystal faces obtained in step 1 are weighed into a corundum boat and transferred into a tube furnace, a mixed gas of hydrogen and argon is introduced, and heating is performed at 400-600°C for 10-40 minutes to obtain crystalline TiO2@amorphous TiO 2-x Core-shell nanoparticle material.

[0008] In the above step 1, preferably, the volume ratio of the hydrofluoric acid to the tetrabutyl titanate is 1:5-15.

[0009] In the above step 1, preferably, the hydrofluoric acid is added to the tetrabutyl titanate, and stirring is performed for 15-45 minutes to obtain a white solution.

[0010] In the above step 1, further preferably, hydrothermal treatment is performed at 180°C for 24 hours.

[0011] In the above step 1, after the reaction is completed, the reaction product is washed with ethanol and water each for 2-3 times, and drying is performed at 70-90°C for 8-16 hours.

[0012] In the above step 2, preferably, the volume ratio of the hydrogen to the argon in the mixed gas is 1:4-9.

[0013] In the above step 2, preferably, the flow rate of the mixed gas is set to 80-120 sccm, and the heating rate is 2-8°C / min.

[0014] In the above step 2, further preferably, heating is performed at 500°C for 30 minutes.

[0015] The crystalline TiO2@amorphous TiO 2-x The core-shell nanoparticle material can be made into a sensor for detecting ethanol gas.

[0016] The beneficial effects of the present application are as follows:

[0017] The present application utilizes a hydrothermal method and hydrogen heat treatment to prepare crystalline TiO2@amorphous TiO 2-x The core-shell nanoparticle material has a simple preparation method. The prepared material is conducive to gas adsorption and gas-sensitive reaction, has an obvious response to 10 ppm ethanol gas at a low temperature (155°C) without light-assisted conditions, can effectively avoid safety hazards, excessive energy consumption and material particle agglomeration at high temperature, is conducive to commercial application of a sensor made of the material, and provides a beneficial reference for application of crystalline@amorphous composite materials in the gas-sensitive field. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The XRD patterns of the products prepared in Comparative Examples 1-3 and Examples 1-3.

[0019] Figure 2 are Raman spectra (a) and partial range amplification graph (b) of the product prepared in Comparative Example 1 and Examples 1-3.

[0020] Figure 3 are scanning electron microscope images of the product prepared in Comparative Example 1 (a), Example 1 (b), Example 2 (c), Example 3 (d), Comparative Example 2 (e) and Comparative Example 3 (f).

[0021] Figure 4 are high-resolution transmission electron microscope images of the product prepared in Comparative Example 1 (a), Example 1 (b), Example 2 (c), Example 3 (d), Comparative Example 2 (e) and Comparative Example 3 (f).

[0022] Figure 5 are response recovery curves of the product prepared in Comparative Examples 1-3 and Example 2 to 10 ppm ethanol gas at 35% RH and 155°C. DETAILED DESCRIPTION

[0023] The application will be further described in detail below in conjunction with the accompanying drawings and examples, but the scope of protection of the application is not limited to these examples.

[0024] Example 1

[0025] Step 1: 4 mL of hydrofluoric acid (concentration of 1.12-1.13 g / cm 3 , purity ≥ 40%) was added to 25 mL of tetrabutyl titanate (density of 0.999-1.003 g / mL, purity ≥ 98.0%), stirred with a magnetic stirrer for 30 min to obtain a white solution; then the white solution was transferred into a 100 mL reactor liner, and hydrothermal treatment was carried out at 180°C for 24 h; the reaction product was washed with ethanol and water for 2 times respectively, and dried at 80°C for 12 h to obtain TiO2 nanosheets exposing {001} crystal faces.

[0026] Step 2: 0.1 g of TiO2 nanosheets exposing {001} crystal faces in step 1 was placed in a corundum boat and transferred into a tube furnace, a mixed gas of hydrogen and argon with a volume ratio of 1:9 was introduced, the flow rate of the mixed gas was set to 100 sccm, the heating rate was 5°C / min, and heating was carried out at 400°C for 30 min to obtain crystalline TiO2@amorphous TiO 2-x core-shell nanoparticle material, named TiO2@TiO 2-x -H2-400°C.

[0027] Example 2

[0028] In step 2 of Example 1, heating was carried out at 500°C for 30 min, and other conditions were the same as in Example 1, to obtain crystalline TiO2@amorphous TiO2-x Core-shell nanoparticle material, named TiO2@TiO 2-x -H2-500℃.

[0029] Example 3

[0030] In step 2 of Example 1, the mixture was heated at 600°C for 30 minutes, with other conditions the same as in Example 1, to obtain crystalline TiO2@amorphous TiO2. 2-x Core-shell nanoparticle material, named TiO2@TiO 2-x -H2-600℃.

[0031] Comparative Example 1

[0032] The TiO2 nanosheets with exposed {001} crystal planes obtained in step 1 of Example 1 are used as Comparative Example 1.

[0033] Comparative Example 2

[0034] Commercial anatase TiO2 nanoparticles purchased from Aladdin Reagents were used as Comparative Example 2 and named Commercial-TiO2.

[0035] Comparative Example 3

[0036] Weigh 0.1g of Commercial-TiO2 and place it in a corundum boat. Transfer the boat to a tube furnace and introduce a mixture of hydrogen and argon in a volume ratio of 1:9. Set the flow rate of the mixture to 100 sccm and the heating rate to 5℃ / min. Heat at 500℃ for 30 min to obtain Commercial-TiO2-H2-500℃.

[0037] The XRD patterns of the products prepared in Comparative Examples 1-3 and Examples 1-3 are as follows: Figure 1 As shown, the XRD diffraction peaks of the six products correspond well with the standard peaks numbered 21–1272, indicating that all six products contain anatase TiO2. Figure 2 The vibrational modes of the products prepared in Comparative Example 1 and Examples 1-3 all exhibit typical Raman spectra of anatase TiO2. Figure 2 The products prepared in Examples 1-3 of b all had a range of 1602.28 cm⁻¹. -1 A peak appears at [location], corresponding to amorphous TiO2. These results indicate that the products of Examples 1-3 obtained by hydrogenation treatment of the sample in Example 1 all possess both crystalline TiO2 and amorphous TiO2. 2-x .Depend on Figure 3 As can be seen, the product prepared in Comparative Example 1 exhibits a plate-like structure. Figure 3 As can be seen from b–f, the products prepared in Examples 1–3 and Comparative Examples 1–2 all exhibit an irregular granular structure. Figure 4It can be seen that the products prepared in Comparative Example 1 and Examples 1-3 all contain a crystal plane with a spacing of 0.352 nm, corresponding to the (101) crystal plane of anatase TiO2 (JCPDS No. 21–1272); crystalline TiO2@amorphous TiO2 nanosheets prepared by hydrogenation at 400℃, 500℃ and 600℃ 2-x The average thicknesses of the amorphous shells of the core-shell nanoparticle materials are 4.850 nm, 8.950 nm, and 3.600 nm, respectively. Figure 4 e and Figure 4 Both Commercial-TiO2 and Commercial-TiO2-H2-500℃ contain crystal planes with an interplanar spacing of 0.352 nm, corresponding to the (101) crystal plane of anatase TiO2 (JCPDS number 21–1272), and no amorphous layer appears on the surface of either sample. These results indicate that hydrogenating TiO2 nanosheets with exposed {001} planes will generate crystalline TiO2@amorphous TiO2. 2-x Core-shell nanoparticles, while hydrogenated commercial TiO2 nanoparticles do not produce an amorphous structure.

[0038] Example 4

[0039] 100 mg of the products prepared in Examples 1, 2, 3, Comparative Examples 1, 2, and 3 were mixed with 0.3 mL of ethanol and ground into a paste. The paste was then coated onto an area with an effective surface area of ​​7 × 7 mm. 2 The corresponding sensor was obtained on the Ag–Pd electrode.

[0040] Gas-sensitive response test procedure: 0.52 μL of ethanol is injected into an evaporating dish in a 20L chamber and evaporated to obtain an ethanol atmosphere with a concentration of 10 ppm. The resistance of the sensor after stabilization in this atmosphere is defined as R. g The resistance of a sensor after stabilization in air is defined as R. a The gas-sensitive response value of the sensor is defined as S = R a / R g .

[0041] from Figure 5 It can be seen that under conditions of 35% RH and 155℃, the response values ​​of Commercial-TiO2 and Commercial-TiO2-H2-500℃ to 10ppm ethanol gas are between 1.00±0.10, indicating that hydrogenation of Commercial-TiO2 under these test conditions cannot improve its ethanol gas response value. Crystalline TiO2@amorphous TiO2 prepared by hydrogenation of TiO2 nanosheets at 500℃ 2-xThe core-shell nanoparticle material has a response of 1.55 to 10 ppm ethanol gas, while the TiO2nanosheet has no obvious response to 10 ppm ethanol gas. This shows that the crystalline TiO2@amorphous TiO 2-x The core-shell nanoparticle material responds to lower concentrations (10 ppm) of ethanol gas at lower temperatures (155°C). This shows that the amorphous TiO 2-x The formation of the shell layer reduces the activation energy of the crystalline TiO2-based sensor, lowers its working temperature, promotes the progress of the gas-sensitive reaction, and improves the response value to ethanol gas. In addition, the increased adsorbed oxygen and the increased air resistance also improve the response value of the crystalline TiO2@amorphous TiO 2-x The response value of the core-shell nanoparticle material to ethanol gas.

Claims

1. A crystalline TiO2@amorphous TiO2core-shell nanoparticle material. 2-x A core-shell nanoparticle material, characterized in that The material is prepared by the following method: Step 1: Hydrofluoric acid is added to tetrabutyl titanate, and stirred to obtain a white solution; the obtained white solution is transferred into a reaction kettle liner, and hydrothermal treatment is carried out at 160-200 ℃ for 20-28 hours; after the reaction is completed, the reaction product is washed with ethanol and water, and dried to obtain TiO2 nanosheets exposing {001} crystal faces; the volume ratio of the hydrofluoric acid to the tetrabutyl titanate is 1:5-15; Step 2: The TiO2nanosheet exposing {001} crystal face in step 1 is weighed into a corundum boat and transferred to a tube furnace, a mixed gas with a volume ratio of hydrogen to argon of 1:4-9 is introduced, and heating is performed at 400-600°C for 10-40 minutes to obtain crystalline TiO2@amorphous TiO2core-shell nanomaterials 2-x Core-shell nanoparticle materials.

2. The crystalline TiO2@amorphous TiO2core-shell nanoparticle material of claim 1, wherein the crystalline TiO2@amorphous TiO2core-shell nanoparticle material has a crystalline TiO2core and an amorphous TiO2shell. 2-x A core-shell nanoparticle material, characterized in that: In step 1, hydrofluoric acid is added to tetrabutyl titanate, and stirred for 15-45 min to obtain a white solution.

3. The crystalline TiO2@amorphous TiO2core-shell nanoparticle material of claim 1, wherein the crystalline TiO2@amorphous TiO2core-shell nanoparticle material has a crystalline TiO2core and an amorphous TiO2shell. 2-x A core-shell nanoparticle material, characterized in that: In step 1, hydrothermal treatment is carried out at 180 ℃ for 24 hours.

4. The crystalline TiO2@amorphous TiO2 according to claim 1 2-x Core-shell nanoparticle materials, characterized by: In step 1, after the reaction is completed, the reaction product is washed with ethanol and water for 2-3 times, and dried at 70-90 ℃ for 8-16 hours.

5. The crystalline TiO2@amorphous TiO2 according to claim 1 2-x Core-shell nanoparticle materials, characterized by: In step 2, the flow rate of the mixed gas is set to 80-120 sccm, and the temperature rising rate is 2-8 ℃ / min.

6. The crystalline TiO2@amorphous TiO of claim 1 or 5 2-x Core-shell nanoparticle material characterized in that: In step 2, heating is carried out at 500 ℃ for 30 min.

7. The crystalline TiO2@amorphous TiO2core-shell nanoparticle material of claim 1. 2-x Use of core-shell nanoparticle materials in ethanol gas detection.

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