Preparation method of monatomic gas-sensitive material based on alloy evolution

Abstract

The invention discloses a preparation method of a monatomic gas-sensitive material based on alloy evolution, the adopted sensitive material is a monatomic Pt-loaded SnO2 sensitive material, and a Pt monatomic modified stannic oxide material is designed and synthesized by taking nitrogen dioxide gas detection as an example. Pt single atoms are thermally emitted to the surface of the SnO2 carrier from the PtSn alloy precursor at high temperature and directly form strong metal-carrier interaction force with the carrier, so that nitrogen dioxide molecules are specifically selected and recognized, and the chemical sensing process is promoted. And the developed Pt1-SnO2 gas sensor has extremely strong anti-interference performance and relatively high gas sensitive activity. The synthesis method of the Pt single atom modified SnO2 as the sensitive material has the advantages of being simple in experimental method, low in economic cost, capable of achieving large-scale preparation and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of sensitive materials and sensor preparation, and particularly relates to a method for preparing a single-atom gas-sensitive material based on alloy evolution. Background Art

[0002] Gas sensors are widely used in industrial production in various fields such as healthcare, environmental protection, smart home, and wearable devices. As one of the largest markets in the sensor market, gas sensors will occupy a huge market share in the future of the entire sensor technology.

[0003] As the core part of gas sensors, sensitive materials have made very important contributions to the recognition of specific target molecules. Traditional metal oxide semiconductors (MOS) have become the first choice for commercial gas sensors due to their low cost, simple structure, good stability, etc., but they still have problems such as high working temperature and low sensitivity. The integration of noble metal nanoparticles and semiconductors has been proven to be an effective strategy to achieve ideal sensing performance, because the synergistic effect of the metal / oxide heterojunction interface can endow the sensitive material with higher activity. However, the high cost and scarcity of noble metals also limit their wide industrial applications. Inspired by the size effect and excellent catalytic activity of metal nanoparticles and nanoclusters, improving the performance of gas sensors by reducing the size of sensing materials has always been the direction of people's efforts. However, the target performance of many important gas sensors is still difficult to achieve.

[0004] In recent years, single-atom catalysts (SACs) have shown satisfactory performance in the field of heterogeneous catalysis. Compared with nanomaterials and nanoclusters, single-atom catalysts can maximize the exposure of active centers and improve the reaction efficiency. The strengthened bonding between single atoms and the support stabilizes the single-atom catalyst and accelerates the charge transfer between the single-atom catalyst and the support. All these characteristics indicate that single-atom catalysts are expected to achieve very excellent gas-sensing performance, because the chemical sensing process is actually a heterogeneous surface catalytic process. However, there are few reports on the synthesis of single-atom gas-sensitive materials with superior performance and high response values at present. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a single-atom gas-sensitive material based on alloy evolution. Taking a nitrogen dioxide gas sensor as an example, the present invention synthesizes a Pt single-atom modified SnO2 material to obtain a highly selective and highly active nitrogen dioxide sensor (Pt1-SnO2). The prepared MEMS sensor can accurately measure the concentration of nitrogen dioxide gas in a complex gas environment, meet the accurate detection of nitrogen dioxide gas in multiple complex scenarios, and the sensor has a high response value, excellent sensitivity, and low working temperature.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A preparation method of a single-atom gas-sensitive material based on alloy evolution, the sensitive material used is a single-atom Pt-loaded SnO2 sensitive material, and this sensitive material is prepared by the following steps:

[0008] (1) Dissolve 9-10 mg of platinum acetylacetonate and 1.5-2 mg of stannous chloride dihydrate in 5 mL of DMF, stir at 30 °C for 8-12 h, then add 80-100 mg of PVP (K30), and continue to stir for 2 h until the solution becomes clear.

[0009] (2) Transfer the pale yellow clear solution obtained in step (1) to a hydrothermal autoclave, keep it at 180-200 °C for 10-12 h, then take it out, naturally cool to room temperature, centrifuge at a speed of 10000 r / min, and wash it by centrifugation with acetone and ethanol for multiple times, and then dry it in a vacuum oven at 70 °C, and cool to room temperature to obtain PtSn alloy.

[0010] (3) Dissolve 1.5-2 g of stannous chloride dihydrate, 1.6-2 g of PVP (K100) and the PtSn alloy synthesized in step (2) in a mixed solvent of 9 mL of DMF and 2 mL of ethanol, stir for more than 24 h to make the solution become a uniform viscous liquid.

[0011] (4) Transfer the solution obtained in step (3) into a 10 mL micro syringe. After adjusting the experimental environment to an environment with 40% humidity and 25 °C, use a voltage of 16-18 kV and a feeding speed of 0.5-0.8 mL / h for electrospinning to collect the corresponding fibers, marked as PtSn-Sn NFs.

[0012] (5) After calcining the fibers obtained in step (4) in an N2 or Ar gas atmosphere and then calcining with air, a single-atom Pt-modified SnO2 sample is obtained, denoted as Pt1-SnO2.

[0013] As a preferred embodiment, the PtSn alloy obtained in step (2) has a diameter of about 20 nm and is cubic.

[0014] As a preferred embodiment, the morphology of the PtSn-Sn NFs obtained in step (4) is fibers modified with cubes, the fiber diameter is about 300-400 nm, and the modification amount of the PtSn alloy is 0.66 wt%.

[0015] As a preferred embodiment, the heating rate in step (5) is 5-10 °C / min and the calcination time is 2 h.

[0016] As a preferred embodiment, a single-atom Pt-loaded SnO2 sensitive material based on alloy evolution can be used for the preparation of a nitrogen dioxide gas sensor, and its specific preparation steps are as follows:

[0017] 1) Mix the Pt1-SnO2 gas-sensitive material with an ethanol solution and grind it in an agate mortar to form a uniform slurry;

[0018] 2) Coat the slurry on the central area of the MEMS chip using a spin coater, evenly covering the interdigital electrodes of the MEMS chip to form a uniform sensitive film. Subsequently, dry it in a vacuum oven at 60 °C for 24 h, and then age the sensor at a voltage of 1.0 V for 72 h to stabilize its performance.

[0019] As a preferred embodiment, the thickness of the sensitive material film for the nitrogen dioxide gas sensor is 20 - 30 μm.

[0020] Technical principle of the present invention: Taking the detection of nitrogen dioxide gas as an example, the present invention designed and synthesized a tin dioxide material modified with Pt single atoms. The Pt single atoms are thermally emitted from the PtSn alloy precursor onto the surface of the SnO2 support at high temperature and directly form strong metal-support interaction forces with the support, thereby specifically selecting and recognizing nitrogen dioxide molecules and promoting the process of chemical sensing. The developed Pt1-SnO2 gas sensor has extremely strong anti-interference ability and high gas-sensing activity, and has very important application value in production and life.

[0021] Compared with the prior art, the present invention has achieved the following results:

[0022] (a) A single-atom gas-sensitive material based on alloy evolution proposed by the present invention provides a new idea for the development of gas sensors;

[0023] (b) The synthesis method of Pt single-atom modified SnO2 proposed by the present invention as a sensitive material has the advantages of simple experimental method, low economic cost, and large-scale preparation;

[0024] (c) Using Pt single-atom modified SnO2 as a sensitive material, the present invention prepared a nitrogen dioxide MEMS sensor with specific recognition. Compared with traditional alloy-sensitized gas sensors, the Pt1-SnO2 sensor proposed by the present invention can accurately detect the concentration of nitrogen dioxide gas in a complex gas environment, and has high response (50 ppb - 50 ppm) to nitrogen dioxide at a lower working temperature (90 °C), as well as good long-term stability and anti-interference ability. Description of the Drawings

[0025] The accompanying drawings of the specification, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0026] Figure 1 X-ray diffraction (XRD) patterns of the SnO2, Pt NPs-SnO2, and Pt1-SnO2 materials prepared in Examples 1, 2, and 3 of the present invention.

[0027] Figure 2 In a, b, and c are the EDS-mapping diagrams of the SnO2, Pt NPs-SnO2, and Pt1-SnO2 gas-sensitive materials prepared in Examples 1, 2, and 3 of the present invention, respectively.

[0028] Figure 3 In a is the high-angle annular dark-field image of the Pt1-SnO2 material prepared in Example 3 of the present invention. Figure 3 In b is the line-scan atomic intensity statistical chart of the high-angle annular dark-field image in Example 3 of the present invention.

[0029] Figure 4 In a is the response value of the Pt1-SnO2 gas sensor prepared in the test of Example 3 of the present invention to nitrogen dioxide gas at different operating temperatures. Figure 4 In b is the selectivity and anti-interference test chart of the Pt1-SnO2 gas sensor prepared in the test of Example 3 of the present invention to different gases at 90°C.

[0030] Figure 5 Response diagram of the Pt1-SnO2 gas sensor prepared in Example 3 of the present invention to nitrogen dioxide at different concentrations at 90°C.

[0031] Figure 6 Anti-interference ability diagram of the Pt1-SnO2 gas sensor prepared in Example 3 of the present invention to a complex environment at 90°C. Detailed implementation manners

[0032] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. For example, as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0034] Example 1:

[0035] A nitrogen dioxide gas sensor made of pure SnO2 sensitive material, and its specific manufacturing process is as follows:

[0036] (1) Weigh 1.2 g of stannous chloride dihydrate and 1.6 g of PVP (K100) and dissolve them in a mixed solution of 9 mL of DMF and 2 mL of ethanol. Stir at 30 °C for more than 24 h until the solution becomes a homogeneous viscous liquid.

[0037] (2) Transfer the solution obtained in step (1) into a 10 mL microsyringe. Using a voltage of 16 kV and a feeding speed of 0.5 mL / h, collect the corresponding fibers through electrospinning technology and label them as Sn NFs.

[0038] (3) Stabilize the fibers obtained in step (2) at 200 °C for 12 h to remove the remaining solvent molecules on the surface.

[0039] (4) Put the stabilized fibers into a tubular furnace in an O2 atmosphere and treat them at 900 °C at a rate of 10 °C / min for 2 h, then collect the corresponding white solid powder and label it as SnO2.

[0040] (5) Construction of a nitrogen dioxide MEMS gas sensor:

[0041] Put the prepared SnO2 gas-sensitive material into a mortar, add ethanol solvent, stir and grind to form a homogeneous slurry. Then use a spin coater to coat the slurry once on the central area of 10 MEMS chips, evenly covering the interdigital electrodes of the MEMS chips to form a uniform sensitive film. Subsequently, continuously dry it in a vacuum oven at 60 °C for 24 h. Place the dried sensor device on a base with heating electrodes and test electrodes and age it at 1.0 V for 72 h to obtain a nitrogen dioxide MEMS gas sensor.

[0042] As Figure 1 shown, the diffraction peaks of the XRD pattern of the synthesized SnO2 are completely consistent with the peaks of the standard pattern (JCPDS No. 41-1445), belonging to hexagonal tin dioxide, and there are no obvious impurity peaks of other metal oxides in the figure, indicating that the sample is a single-phase SnO2 material.

[0043] As Figure 2 shown in a of [[ID=]], the morphology of the synthesized SnO2 is a nanorod composed of nanoparticles, with a diameter of about 150 - 200 nm, and the EDS spectrum proves the existence of Sn and O elements. It is confirmed that the sample is a single-phase SnO2 material.

[0044] Example 2:

[0045] A nitrogen dioxide gas sensor with a SnO2 sensitive material modified by Pt nanoparticles, and its specific manufacturing process is as follows:

[0046] (1) Weigh 1.2 g of stannous chloride dihydrate and 1.6 g of PVP (K100) and dissolve them in a mixed solution of 9 mL of DMF and 2 mL of ethanol. Stir at 30 °C for more than 24 h until the solution becomes a homogeneous viscous liquid.

[0047] (2) Transfer the solution obtained in step (1) into a 10 mL microsyringe. Using a voltage of 16 kV and a pushing speed of 0.5 mL / h, collect the corresponding fibers by electrospinning technology and label them as Sn NFs.

[0048] (3) Stabilize the fibers obtained in step (2) at 200 °C for 12 h to remove the remaining solvent molecules on the surface.

[0049] (4) Put the stabilized fibers into a tubular furnace in an O2 atmosphere and treat them at 900 °C at a rate of 10 °C / min for 2 h, then collect the corresponding white solid powder and label it as SnO2.

[0050] (5) Add the freshly prepared sodium borohydride solution (20 mg of sodium borohydride dissolved in 10 mL of deionized water) to 50 mL of 0.1 mmol / L PtCl4 aqueous solution. After reacting the mixed solution in a water bath at 80 °C for 60 min, wash it by centrifugation alternately with ethanol and acetone, and dry it to obtain a black sample.

[0051] (6) Disperse 100 mg of SnO2 in a mixed solution of 20 mL of ethanol and 20 mL of deionized water, add 1 mg of Pt nanoparticles, stir at 30 °C for 24 h, then centrifuge, wash, and dry to obtain Pt NPs - SnO2.

[0052] (7) Construction of a nitrogen dioxide MEMS gas sensor:

[0053] Put the prepared SnO2 gas-sensitive material into a mortar, add ethanol solvent, and stir and grind to form a homogeneous slurry. Then, use a spin coater to coat the slurry once on the central area of 10 MEMS chips, evenly covering the interdigital electrodes of the MEMS chips to form a uniform sensitive film, and then continuously dry it in a vacuum oven at 60 °C for 24 h. Place the dried sensor device on a base with heating electrodes and test electrodes and age it at 1.0 V for 72 h to obtain a nitrogen dioxide MEMS gas sensor.

[0054] As Figure 1 shown, the diffraction peaks of the XRD pattern of the synthesized Pt NPs-SnO2 are completely consistent with the peaks of the standard pattern (JCPDS No. 41-1445), belonging to hexagonal tin dioxide, and there are no obvious impurity peaks of other metal oxides in the figure, indicating that the sample is a pure-phase SnO2 material.

[0055] As Figure 2 shown in b of [], it can be seen from the EDS image of the synthesized Pt NPs-SnO2 that Pt nanoparticles are successfully modified onto the nanorods of tin dioxide, and the diameter of the nanoparticles is about 20-30 nm.

[0056] Example 3:

[0057] Dissolve 9-10 mg of platinum acetylacetonate and 1.5-2 mg of stannous chloride dihydrate in 5 mL of DMF, stir at 30 °C for 8-12 h, then add 80-100 mg of PVP (K30), and continue to stir for 2 h until the solution becomes clear.

[0058] Transfer the pale yellow clear solution obtained in step (1) to a hydrothermal reactor, keep it at 180-200 °C for 10-12 h, then take it out, naturally cool it to room temperature, centrifuge it at a speed of 10000 r / min, and wash it by centrifugation with acetone and ethanol multiple times, and then dry it in a vacuum oven at 70 °C, and cool it to room temperature to obtain PtSn alloy.

[0059] Dissolve 1.5-2 g of stannous chloride dihydrate, 1.6-2 g of PVP (K100) and the PtSn alloy synthesized in step (2) in a mixed solvent of 9 mL of DMF and 2 mL of ethanol, stir for more than 24 h until the solution becomes a homogeneous viscous liquid.

[0060] Transfer the solution obtained in step (3) into a 10 mL microsyringe. After adjusting the experimental environment to a humidity of 40% and a temperature of 25 °C, use an electrostatic spinning voltage of 16-18 kV and a feeding speed of 0.5-0.8 mL / h to collect the corresponding fibers, marked as PtSn-Sn NFs.

[0061] After calcining the fibers obtained in step (4) in an atmosphere of N2 or Ar gas and then in air, a single-atom Pt-modified SnO2 sample, denoted as Pt1-SnO2, is obtained.

[0062] Construction of a nitrogen dioxide MEMS gas sensor:

[0063] Put the prepared SnO2 gas-sensitive material into a mortar, add an ethanol solvent, and stir and grind to form a uniform slurry. Then, use a spin coater to coat the slurry once on the central area of 10 MEMS chips, evenly covering the interdigital electrodes of the MEMS chips to form a uniform sensitive film, and then continuously dry it in a vacuum oven at 60 °C for 24 h. Place the dried sensor device on a base with heating electrodes and test electrodes and age it at 1.0 V for 72 h to obtain a nitrogen dioxide MEMS gas sensor.

[0064] As Figure 1 shown, the diffraction peaks of the XRD pattern of the synthesized Pt1-SnO2 are completely consistent with the peaks of the standard pattern (JCPDS No. 41-1445), belonging to tetragonal tin dioxide, and there are no obvious impurity peaks of other metal oxides in the figure, indicating that the sample is a single-phase SnO2 material.

[0065] As Figure 2 shown in c, the EDS-mapping image of the synthesized Pt1-SnO2 shows that no aggregated Pt particles are generated in the Pt1-SnO2 sample, and the Pt element is evenly covered on the surface of SnO2, confirming that the Pt element exists in the Pt1-SnO2 sample in the form of single atoms.

[0066] As Figure 3 shown in a, in the Pt1-SnO2 sample, the Pt on the surface of tin dioxide is distributed in the form of single atoms, and there are no aggregated Pt nanoparticles. Figure 3 The linear analysis in b further verifies the distribution pattern of the noble metal in the sample.

[0067] As Figure 4 shown in a, the response value change of the MEMS sensor to 5 ppm nitrogen dioxide gas in the temperature range of 70 °C to 170 °C is shown. As the temperature increases, the response of the sensor first increases and then decreases, and shows a maximum value at 90 °C. Therefore, the optimal working temperature of the sensor is 90 °C.

[0068] Figure 4 shown in b, the response value curve of the Pt1-SnO2 sensor in different nitrogen dioxide concentration ranges is shown, demonstrating the excellent nitrogen dioxide sensing performance of the MEMS sensor at a relatively low working temperature.

[0069] Figure 5 It shows the relationship between the response of the sensor to nitrogen dioxide and the concentration. As the concentration increases, the response value of the sensor also increases, indicating that the response value is positively correlated with the nitrogen dioxide concentration. The fitting result of the corresponding linear relationship between the nitrogen dioxide concentration and the sensor response is as Figure 4 shown in b of []. It shows that the sensor has a good linear coefficient.

[0070] Figure 6 It shows that the sensor has strong anti-interference ability to three gases, hydrogen sulfide, sulfur dioxide and ammonia. In a complex environment where nitrogen dioxide gas coexists with these three gases, the sensor shows extremely small changes in the response value, proving that the sensor has extremely strong anti-interference ability in a complex environment.

[0071] In summary, the single-atom gas-sensitive material Pt1-SnO2 based on alloy evolution can be used as the sensitive material of a nitrogen dioxide sensor to achieve efficient detection of nitrogen dioxide gas. In the above embodiment, the PtSn alloy is thermally emitted onto the surface of tin dioxide oxide by electrospinning and heat treatment in one step, and is loaded in the form of single atoms to obtain the Pt1-SnO2 composite material. The unique adsorption sites on the surface of the single-atom catalyst can specifically recognize nitrogen dioxide gas molecules. Combining the Pt1-SnO2 composite material with a MEMS chip results in a MEMS gas sensor for detecting nitrogen dioxide gas. The single-atom Pt-loaded tin dioxide sensor prepared in the above embodiment exhibits very excellent gas-sensing performance, which has surpassed the reported nitrogen dioxide gas sensors. Moreover, it can accurately identify nitrogen dioxide gas in a complex gas atmosphere, and has the advantages of a low working temperature, high response, and good stability.

[0072] The above are only the preferred embodiments of the present invention and do not limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a single-atom gas-sensitive material based on alloy evolution, characterized in that, The sensitive material used is SnO2 sensitive material loaded with single-atom Pt, and this sensitive material is prepared by the following steps: (1) Dissolve 9 - 10 mg of platinum acetylacetonate and 1.5 - 2 mg of stannous chloride dihydrate in 5 mL of DMF, stir at 30 °C for 8 - 12 h, then add 80 - 100 mg of PVP (K30), and continue stirring for 2 h until the solution becomes clear. (2) Transfer the pale yellow clear solution obtained in step (1) to a hydrothermal autoclave, keep it at 180 - 200 °C for 10 - 12 h, then take it out, naturally cool to room temperature, centrifuge at a speed of 10000 r / min, and wash it by centrifugation with acetone and ethanol multiple times. Then dry it in a vacuum oven at 70 °C, and after cooling to room temperature, obtain PtSn alloy. (3) Dissolve 1.5 - 2 g of stannous chloride dihydrate, 1.6 - 2 g of PVP (K100) and the PtSn alloy synthesized in step (2) in a mixed solvent of 9 mL of DMF and 2 mL of ethanol, stir for more than 24 h until the solution becomes a homogeneous viscous liquid. (4) Transfer the solution obtained in step (3) into a 10 mL micro syringe. After adjusting the experimental environment to a humidity of 40% and a temperature of 25 °C, use an electrostatic spinning voltage of 16 - 18 kV and a feeding rate of 0.5 - 0.8 mL / h to collect the corresponding fibers, marked as PtSn - Sn NFs. (5) After calcining the fibers obtained in step (4) in an N2 or Ar atmosphere and then in air, obtain a single-atom Pt-modified SnO2 sample, denoted as Pt1 - SnO2.

2. The preparation method of a single-atom gas-sensing material based on alloy evolution according to claim 1, wherein The PtSn alloy obtained in step (2) has a cubic shape with a diameter of about 20 nm.

3. The preparation method of a single-atom gas-sensing material based on alloy evolution according to claim 1, characterized in that, The morphology of the PtSn - Sn NFs obtained in step (4) is fibers modified with cubes, the fiber diameter is about 300 - 400 nm, and the modification amount of the PtSn alloy is 0.66 wt%.

4. The preparation method of a single-atom gas-sensitive material based on alloy evolution according to claim 1, characterized in that, The heating rate in step (5) is 5 - 10 °C / min, and the calcination time is 2 h.

5. The preparation method of a single-atom gas-sensing material based on alloy evolution according to claim 1, characterized in that, The SnO2 sensitive material loaded with single-atom Pt based on alloy evolution can be used for the preparation of a nitrogen dioxide gas sensor, and its specific preparation steps are as follows: 1) Mix the Pt1 - SnO2 gas-sensitive material with an ethanol solution and grind it in an agate mortar to form a uniform slurry; 2) Coat the slurry on the central area of the MEMS chip using a spin coater, evenly cover it on the interdigital electrodes of the MEMS chip to form a uniform sensitive film. Then dry it in a vacuum oven at 60 °C for 24 h, and age the sensor at a voltage of 1.0 V for 72 h to stabilize the performance.

6. The preparation method of a single-atom gas-sensing material based on alloy evolution according to claim 5, wherein, The thickness of the sensitive material film for the nitrogen dioxide gas sensor is 20 - 30 μm.

Images