A MIL-100(Fe)-derived ErFeO3 / α-Fe2O3 gas-sensitive material, its preparation method and application

Abstract

This invention relates to a MIL-100(Fe)-derived ErFeO3 / α-Fe2O3 gas-sensitive material, its preparation method, and its application, belonging to the field of gas sensor and environmental monitoring technology. A method for preparing a MIL-100(Fe)-derived ErFeO3 / α-Fe2O3 gas-sensitive material involves: slowly adding FeCl3 solution dropwise to H3BTC solution at room temperature; after uniform mixing, maintaining the mixture at 150℃~210℃ for 20 hours in a reaction vessel to obtain an orange-red substance; washing and drying to obtain MIL-100(Fe); dispersing the obtained MIL-100(Fe) in methanol; dissolving Er(NO3)3·6H2O in the above solution and reacting for a period of time; washing, centrifuging, and drying; transferring the obtained product to a muffle furnace and calcining under an oxygen atmosphere to obtain the ErFeO3 / α-Fe2O3 gas-sensitive material. The method for preparing porous metal oxide-based gas-sensitive materials using MOF materials as precursors and rare earth element modification proposed in this invention has advantages such as versatility, controllability, and recyclability compared to traditional methods for preparing metal oxide-based gas-sensitive materials.

Description

Technical Field

[0001] This invention relates to a MIL-100(Fe)-derived ErFeO3 / α-Fe2O3 gas-sensitive material, its preparation method, and its application, belonging to the field of gas sensor and environmental monitoring technology. Background Technology

[0002] Acetone, with the chemical formula CH3COCH3, is a colorless liquid commonly used as a solvent and industrial raw material. Acetone is irritating; contact with skin and eyes can cause irritation and inflammation. High concentrations of acetone vapor can damage the respiratory system, central nervous system, and liver. Acetone is also a flammable liquid; contact with open flames or high temperatures may cause fires or explosions. As a common organic solvent and industrial raw material, leaks or releases of acetone in industrial production and laboratories can pose hazards to human health and the environment. Gas sensors are required to monitor and control acetone concentrations.

[0003] Biomarkers in exhaled breath refer to information that can be used for disease diagnosis and monitoring by analyzing specific chemical components in exhaled breath. Gases and volatile organic compounds (VOCs) are typical biomarkers, expelled from the alveoli during respiration and reflecting the body's internal physiological and metabolic state. Most diseases and health conditions affect metabolic processes within the body, thus influencing the chemical composition of exhaled breath. By analyzing biomarkers in exhaled breath, information about an individual's health status can be obtained non-invasively, facilitating early disease diagnosis, disease monitoring, and treatment effectiveness.

[0004] Metal-organic frameworks (MOFs) possess advantages such as high tunability, large porosity, and high selectivity, making them promising for applications in gas separation, storage, sensing, and catalysis. However, pure MOFs, as gas-sensitive materials, have limited responsiveness to gases due to their poor conductivity. Therefore, researchers often use MOFs as precursors to prepare three-dimensional porous metal oxide materials through oxidative calcination. The resulting materials exhibit significantly improved gas adsorption performance and enhanced sensitivity, thus becoming novel gas-sensitive materials with distinctive characteristics. Therefore, the preparation of a gas-sensitive material with high porosity, large specific surface area, and high sensitivity is of significant practical importance. Summary of the Invention

[0005] To overcome the existing technical problems and achieve high response to acetone and high humidity detection, this patent provides a method for preparing a MIL-100(Fe)-derived ErFeO3 / α-Fe2O3 gas sensor with high sensitivity, good moisture resistance, and good stability.

[0006] This invention aims to create a highly sensitive oxide gas sensor. A MIL-100(Fe) precursor is prepared via a simple hydrothermal method. By adjusting the mass ratio of Er(NO3)3·6H2O to MIL-100(Fe) and the impregnation time and temperature, an ErFeO3 / α-Fe2O3 acetone gas sensor is obtained. This embodiment fully utilizes the large specific surface area and high porosity of MOFs to prepare a MOF-derived ErFeO3 / α-Fe2O3 gas sensor with high sensitivity, high moisture resistance, and long-term stability to acetone gas.

[0007] A method for preparing a MIL-100(Fe)-derived ErFeO3 / α-Fe2O3 gas-sensitive material involves the following steps: At room temperature, a FeCl3 solution with a concentration of 2 g / L to 8 g / L is slowly added dropwise to an H3BTC solution with a concentration of 16.6 g / L to 66.6 g / L. After uniform mixing, the mixture is kept at 150℃ to 210℃ for 20 h in a reaction vessel to obtain an orange-red substance. This substance is then washed and dried to obtain MIL-100(Fe). The obtained MIL-100(Fe) is dispersed in methanol, and Er(NO3)3·6H2O is dissolved in the above solution and reacted for a period of time. The mixture is then washed, centrifuged, and dried. The resulting product is transferred to a muffle furnace and heated to 400℃ at a heating rate of 5℃ / min under an oxygen atmosphere, and held for 2 h to obtain the ErFeO3 / α-Fe2O3 gas-sensitive material.

[0008] Preferably, the mass ratio of FeCl3 to H3BTC is 1:1 to 4; the mass ratio of MIL-100(Fe) to Er(NO3)3·6H2O is 5:5 to 20; and the ratio of MIL-100(Fe) to methanol is 5g:1000mL.

[0009] Most preferably, the mass ratio of FeCl3 to H3BTC is 1:2; the mass ratio of MIL-100(Fe) to Er(NO3)3·6H2O is 1:2.

[0010] Preferably, the obtained orange-red substance is washed alternately with deionized water and anhydrous ethanol until no colored impurities appear in the mother liquor; the washed product is then vacuum dried at 80°C to obtain MIL-100(Fe).

[0011] Preferably, the obtained MIL-100(Fe) is dispersed in methanol and magnetically stirred for 20-60 min.

[0012] Preferably, the mixture is kept at 180°C for 20 hours in the reactor to obtain an orange-red substance.

[0013] Another object of the present invention is to provide an ErFeO3 / α-Fe2O3 gas-sensitive material prepared by the above method.

[0014] Another object of the present invention is to provide a method for preparing an acetone gas sensor comprising the above-mentioned ErFeO3 / α-Fe2O3 gas-sensitive material.

[0015] A method for preparing an acetone gas sensor involves coating the ErFeO3 / α-Fe2O3 gas-sensitive material onto an Al2O3 ceramic tube, allowing it to dry naturally, and then aging it at a heating temperature of 300°C to remove impurities.

[0016] The sensor provided by this invention is a resistive metal oxide-based acetone gas sensor. In an air atmosphere, the resistivity of ErFeO3 / α-Fe2O3 increases due to the adsorption of oxygen molecules from the air on its surface. When the sensor is in an acetone atmosphere, acetone reacts with active oxygen ions on the ErFeO3 / α-Fe2O3 surface, resulting in a low resistance in the material. The change in resistance from high to low reflects the sensor's response to acetone.

[0017] The beneficial effects of this invention are as follows: Compared with traditional methods for preparing metal oxide-based gas-sensitive materials, the method proposed in this invention, which uses MOF materials as precursors and modifies them with rare earth elements to prepare porous metal oxide-based gas-sensitive materials, has advantages such as versatility, controllability, and recyclability. The ErFeO3 / α-Fe2O3 sensing material prepared by this invention exhibits high sensitivity, high moisture resistance, and stable response to acetone during long-term detection. The ErFeO3 / α-Fe2O3 sensor prepared by this invention can maintain high sensitivity to acetone in high humidity environments, and can adapt to the detection needs of complex environments. Attached Figure Description

[0018] Figure 1 Scanning electron microscope (SEM) images of the prepared ErFeO3 / α-Fe2O3 material;

[0019] Figure 2 EDS image of the prepared ErFeO3 / α-Fe2O3 material;

[0020] Figure 3 This is a statistical graph showing the response values ​​of the sensor in Embodiment 1 of the present invention when exposed to 100 ppm acetone gas;

[0021] Figure 4 This is the acetone response recovery curve of the sensor in Embodiment 1 of the present invention when exposed to different humidity levels.

[0022] The response value S of a gas sensor is defined as: Response = R a / R g , where R a and R gThese represent the sensor's resistance values ​​in air and in acetone, respectively. Detailed Implementation

[0023] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0024] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0025] A method for preparing an acetone gas sensor includes the following process steps:

[0026] Step (1) Take a certain amount of H3BTC (0.5-2.0g) and add it to a round-bottom flask. Add 30ml of deionized water and sonicate for 5min. Record this as solution A. Then weigh a certain amount of FeCl3·6H2O (0.2-0.8g), add 100ml of deionized water and sonicate to dissolve it. Record this as solution B. Under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h. Transfer the mixture to a stainless steel reactor and keep it at a suitable temperature (150℃-210℃) for 20h.

[0027] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0028] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh an appropriate amount of Er(NO3)3·6H2O (0.5g-2g) and dissolve it in the above solution, and stir magnetically for 20-60min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0029] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

[0030] Preferably, the optimal amount of H3BTC added in step (1) is 1g.

[0031] Preferably, the optimal amount of FeCl3·6H2O added in step (1) is 0.5g.

[0032] Preferably, the optimal heat preservation temperature described in step (1) is 180°C.

[0033] Preferably, the optimal amount of Er(NO3)3·6H2O added in step (3) is 1g.

[0034] Preferably, the optimal time for magnetic stirring in step (3) is 40 min.

[0035] Example 1

[0036] Step (1) Take 0.5g of H3BTC and add it to a round-bottom flask. Add 30ml of deionized water and sonicate for 5min. Record this as solution A. Then weigh 0.2g of FeCl3·6H2O, add 100ml of deionized water and sonicate to dissolve. Record this as solution B. Under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h. Transfer the mixture to a stainless steel reactor and keep it at 150℃ for 20h.

[0037] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0038] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh 0.5g of Er(NO3)3·6H2O and dissolve it in the above solution, stir magnetically for 20min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0039] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

[0040] Example 2

[0041] Step (1) Take 0.5g of H3BTC and add it to a round-bottom flask. Add 30ml of deionized water and sonicate for 5min. Record this as solution A. Then weigh 0.2g of FeCl3·6H2O, add 100ml of deionized water and sonicate to dissolve. Record this as solution B. Under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h. Transfer the mixture to a stainless steel reactor and keep it at 150℃ for 20h.

[0042] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0043] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh 0.5g of Er(NO3)3·6H2O and dissolve it in the above solution, stir magnetically for 40min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0044] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

[0045] Example 3

[0046] Step (1) Take 1g of H3BTC and add it to a round-bottom flask, add 30ml of deionized water; sonicate for 5min, and record it as solution A; then weigh 0.4g of FeCl3·6H2O, add 100ml of deionized water and sonicate to dissolve, and record it as solution B; under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h; transfer the mixture to a stainless steel reactor and keep it at 180℃ for 20h.

[0047] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0048] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh 0.5g of Er(NO3)3·6H2O and dissolve it in the above solution, stir magnetically for 20min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0049] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

[0050] Example 4

[0051] Step (1) Take 1g of H3BTC and add it to a round-bottom flask, add 30ml of deionized water; sonicate for 5min, and record it as solution A; then weigh 0.4g of FeCl3·6H2O, add 100ml of deionized water and sonicate to dissolve, and record it as solution B; under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h; transfer the mixture to a stainless steel reactor and keep it at 180℃ for 20h.

[0052] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0053] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh 1g of Er(NO3)3·6H2O and dissolve it in the above solution, stir magnetically for 40min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0054] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

[0055] Example 5

[0056] Step (1) Take 1.5g of H3BTC and add it to a round-bottom flask. Add 30ml of deionized water and sonicate for 5min. Record this as solution A. Then weigh 0.6g of FeCl3·6H2O, add 100ml of deionized water and sonicate to dissolve. Record this as solution B. Under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h. Transfer the mixture to a stainless steel reactor and keep it at 210℃ for 20h.

[0057] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0058] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh 2g of Er(NO3)3·6H2O and dissolve it in the above solution, stir magnetically for 60min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0059] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

[0060] Example 6

[0061] Step (1) Take 1.5g of H3BTC and add it to a round-bottom flask. Add 30ml of deionized water and sonicate for 5min. Record this as solution A. Then weigh 0.8g of FeCl3·6H2O, add 100ml of deionized water and sonicate to dissolve. Record this as solution B. Under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h. Transfer the mixture to a stainless steel reactor and keep it at 210℃ for 20h.

[0062] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0063] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh 2g of Er(NO3)3·6H2O and dissolve it in the above solution, stir magnetically for 40min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0064] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

[0065] Example 7

[0066] Step (1) Take 2g of H3BTC and add it to a round-bottom flask. Add 30ml of deionized water and sonicate for 5min. Record this as solution A. Then weigh 0.8g of FeCl3·6H2O, add 100ml of deionized water and sonicate to dissolve. Record this as solution B. Under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h. Transfer the mixture to a stainless steel reactor and keep it at 180℃ for 20h.

[0067] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0068] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh 1g of Er(NO3)3·6H2O and dissolve it in the above solution, stir magnetically for 40min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0069] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

[0070] Example 8

[0071] Step (1) Take 2g of H3BTC and add it to a round-bottom flask. Add 30ml of deionized water and sonicate for 5min. Record this as solution A. Then weigh 0.4g of FeCl3·6H2O, add 100ml of deionized water and sonicate to dissolve. Record this as solution B. Under stirring, slowly add solution B to solution A at room temperature and continue stirring for 2h. Transfer the mixture to a stainless steel reactor and keep it at 180℃ for 20h.

[0072] Step (2) The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

[0073] Step (3) Disperse 0.5g of MIL-100(Fe) material in 100ml of methanol, weigh 1g of Er(NO3)3·6H2O and dissolve it in the above solution, stir magnetically for 60min; then wash, centrifuge and dry; transfer the obtained product to a muffle furnace, heat to 400℃ at a heating rate of 5℃ / min under oxygen atmosphere, and hold for 2h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

[0074] Step (4) Take 0.05g ErFeO3 / α-Fe2O3 powder and 1ml deionized water, grind them into a slurry, apply it to the Al2O3 ceramic tube with a paint brush, let it dry naturally, and then age it at a heating temperature of 300℃ to remove impurities.

Claims

1. A method for preparing a MIL-100(Fe)-derived ErFeO3 / α-Fe2O3 gas-sensitive material, characterized in that: At room temperature, FeCl3 solution with a concentration of 2 g / L to 8 g / L was slowly added dropwise to H3BTC solution with a concentration of 16.6 g / L to 66.6 g / L. After uniform mixing, the mixture was kept at 150°C to 210°C for 20 h in a reaction vessel to obtain an orange-red substance. The substance was washed and dried to obtain MIL-100(Fe). The obtained MIL-100(Fe) was dispersed in methanol, and Er(NO3)3·6H2O was dissolved in the obtained solution. The mixture was magnetically stirred for 20-60 min, washed, centrifuged, and dried. The obtained product was transferred to a muffle furnace and heated to 400°C at a heating rate of 5°C / min under an oxygen atmosphere and held for 2 h to obtain ErFeO3 / α-Fe2O3 gas-sensitive material.

2. The method according to claim 1, characterized in that: The mass ratio of FeCl3 to H3BTC is 1:1~4; the mass ratio of MIL-100(Fe) to Er(NO3)3·6H2O is 5:5~20; and the ratio of MIL-100(Fe) to methanol is 5g:1000mL.

3. The method according to claim 2, characterized in that: The mass ratio of FeCl3 to H3BTC is 1:2; the mass ratio of MIL-100(Fe) to Er(NO3)3·6H2O is 1:

2.

4. The method according to claim 1, characterized in that: The obtained orange-red substance was washed alternately with deionized water and anhydrous ethanol until no colored impurities appeared in the mother liquor; the washed product was dried under vacuum at 80°C to obtain MIL-100(Fe).

5. The method according to claim 1, characterized in that: The mixture was kept at 180°C for 20 hours in a reactor to obtain an orange-red substance.

6. The ErFeO3 / α-Fe2O3 gas-sensitive material prepared by the method according to any one of claims 1 to 5.

7. A method for preparing an acetone gas sensor, characterized in that: The ErFeO3 / α-Fe2O3 gas-sensitive material as described in claim 6 was coated onto an Al2O3 ceramic tube, naturally dried, and then aged at a heating temperature of 300°C to remove impurities.

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