Pt-w03 nanofiber material based on water-based one-step electrospinning method and preparation method and gas sensor thereof

Abstract

The application discloses a Pt-WO3 nanofiber material based on a water-based one-step electrospinning method, a preparation method thereof and a gas sensor. The material is prepared by a water-based electrospinning method with H2O as a solvent, has a one-dimensional nanofiber structure and morphology, and is favorable for electron conduction. The nanofiber material has abundant oxygen vacancies and a large specific surface area, can regulate a carrier concentration, provides more active adsorption sites for chemisorbed oxygen and target gas, and is favorable for improving gas sensitivity. In addition, the surface-modified Pt has a catalytic effect and an overflow effect, forms a Schottky barrier with WO3, produces a depletion layer, and enhances gas sensitivity response. The sensor has high sensitivity and high selectivity to low-concentration acetone gas, has short response and recovery times, and has excellent long-term stability, and has great application prospects in the fields of acetone-based diabetes breath analysis diagnosis and industrial low-concentration acetone gas detection.

Description

Technical Field

[0001] This invention belongs to the field of gas sensors, and relates to a Pt-WO3 nanofiber material based on a water-based one-step electrospinning method, its preparation method, and a gas sensor. Background Technology

[0002] Diabetes is one of the most important health problems in the 21st century, affecting hundreds of millions of people worldwide. Therefore, its diagnosis and real-time monitoring are crucial. Breath analysis, as a non-invasive, painless, and real-time detection method, offers significant advantages in diabetes diagnosis. Among these methods, gas sensor analysis is the simplest and most cost-effective. Gas sensors offer advantages such as high sensitivity, selectivity, stability, rapid response, and low price, and are widely used in industrial safety, environmental monitoring, food safety, and medical diagnostics. They are also suitable for detecting explosive, flammable, and toxic gases. Acetone is an important biomarker for diagnosing diabetes through breath analysis. The concentration of acetone exhaled by humans is correlated with blood glucose levels in diabetic patients. Generally, the concentration of acetone in the breath of normal individuals is 0.2–1.8 ppm, while that in diabetic patients is typically 1.25–2.5 ppm. Furthermore, acetone concentrations exceeding 173 ppm can severely affect the central nervous system and damage vital organs, and long-term exposure can also harm the eyes and nose. Therefore, the preparation of sensing materials and sensors for low-concentration acetone gas is necessary and of great significance. However, existing acetone gas sensing materials and sensors still suffer from drawbacks such as complex preparation methods, high detection concentrations, and low response values. This invention employs a simple water-based one-step electrospinning method to prepare nanofiber materials and sensors with high response to low-concentration acetone gas, which have significant application value. Summary of the Invention

[0003] To address the aforementioned problems, the present invention aims to provide a Pt-WO3 nanofiber material based on a water-based one-step electrospinning method, its preparation method, and a gas sensor. The sensor of the present invention, based on Pt-WO3 nanofiber material, possesses gas-sensing properties such as high sensitivity, fast response recovery speed, excellent selectivity, and good long-term stability, and is expected to be applied to acetone-based expiratory breath analysis and diagnosis of diabetes, as well as industrial low-concentration acetone gas detection.

[0004] The technical solution of the present invention is as follows:

[0005] A method for preparing Pt-WO3 nanofiber material based on water-based one-step electrospinning includes the following steps: mixing and dissolving ammonium metatungstate hydrate, chloroplatinic acid solution, polyvinylpyrrolidone and water to obtain a precursor solution; electrospinning the precursor solution to obtain precursor fibers; and drying and calcining the precursor fibers to obtain Pt-WO3 nanofiber material.

[0006] Preferably, the mass ratio of ammonium metatungstate hydrate, polyvinylpyrrolidone and water is 1:0.8-1.2:8-10.

[0007] Preferably, the volume ratio of the chloroplatinic acid solution to water is 1:5 to 15, wherein the concentration of the chloroplatinic acid solution is 10 mmol / mL.

[0008] Preferably, the electrospinning step is as follows: transferring the precursor solution into a syringe, adjusting the electrospinning parameters, and collecting the precursor fibers at the collection-side receiver.

[0009] Preferably, the electrospinning parameters are as follows: 10mL plastic syringe, 22G steel needle, positive high voltage of 10-15kV, negative high voltage of 1-3kV, extrusion speed of the spinneret of 0.5-0.8mL / h, distance between the needle and the receiver on the collection side of 14-20cm, electrospinning machine temperature of 30-60℃, and humidity of 30%-60%, to ensure continuous electrospinning.

[0010] Preferably, the drying temperature is 50-80°C and the drying time is 12-36 hours.

[0011] Preferably, the calcination temperature is 400–600°C, the time is 1–3 h, and the heating rate is 1–3°C / min.

[0012] A Pt-WO3 nanofiber material was prepared using the method described above. The nanofibers consist of WO3 crystals, with Pt loaded on the surface of the nanofiber material. The Pt-WO3 nanofiber material was used for the detection of low-concentration acetone gas at an operating temperature of 300°C. At 25% humidity, it exhibited a response value of 82 for 1.8 ppm acetone gas, a response time of 6 s, and a recovery time of 107 s.

[0013] A gas sensor utilizes the aforementioned Pt-WO3 nanofiber material as the sensitive layer material. The Pt-WO3 nanofiber material is ground and then coated onto a planar interdigitated electrode. The specific preparation method is as follows: 10–20 g of the Pt-WO3 nanofiber material is weighed and placed in an agate mortar. 60–100 μL of ethanol is added, and the mixture is thoroughly ground until a paste-like slurry is formed. This paste is then coated onto a ceramic substrate with Au interdigitated electrodes deposited on its surface to construct the gas sensor. Subsequently, the gas sensor is placed in an oven, and the drying temperature is set to 50–80 °C for 12–36 h.

[0014] Furthermore, the sensor is used for acetone-based breath analysis diagnosis of diabetes and for the detection of low-concentration acetone gas in industrial applications.

[0015] The beneficial effects of this invention are as follows:

[0016] (1) This invention employs a unique water-based one-step electrospinning technology, using water as the solvent for the spinning precursor. The resulting Pt-WO3 nanofibers have a one-dimensional nanofiber structure, which is beneficial for electron conduction. Furthermore, compared to materials obtained by traditional DMF-based electrospinning, these nanofibers have more oxygen vacancies and a larger specific surface area, providing more active gas adsorption sites and making a significant contribution to improving gas-sensing performance.

[0017] (2) The gas sensor made of Pt-WO3 nanofibers based on water-based one-step electrospinning provided by the present invention has excellent gas sensing performance: at a working temperature of 300℃, it has a response value of up to 82 for 1.8ppm acetone gas with 25% humidity, which is 8 times higher than that of the material and corresponding gas sensor obtained by the traditional DMF-based electrospinning method; in addition, its response time is 6s and its recovery time is 107s, with rapid response and recovery, and it has excellent selectivity, anti-interference ability and long-term stability.

[0018] (3) The water-based one-step electrospinning method for preparing Pt-WO3 nanofibers and gas sensors described in this invention is simple and controllable, requires simple and easy-to-operate instruments and equipment, has a short production cycle, low cost, is non-toxic and non-polluting to the environment, and has good repeatability, and can be applied to production.

[0019] (4) The Pt-WO3 nanofiber and gas sensor based on water-based one-step electrospinning method provided by the present invention is expected to be used for acetone-based breath analysis diagnosis of diabetes and detection of low concentration acetone gas in industry. Attached Figure Description

[0020] Figure 1 This is the XRD pattern of Pt-WO3 nanofibers in an embodiment of the present invention.

[0021] Figure 2These are SEM images of Pt-WO3 nanofibers in the embodiments of the present invention, wherein (a) is an SEM image of Pt-WO3 nanofibers produced by DMF-based one-step electrospinning and (b) is an SEM image of Pt-WO3 nanofibers produced by water-based one-step electrospinning.

[0022] Figure 3 This is the EDS energy spectrum of Pt-WO3 nanofibers in an embodiment of the present invention.

[0023] Figure 4 These are BET diagrams of the Pt-WO3 nanofibers described in the embodiments of the present invention. (a) is a BET diagram of Pt-WO3 nanofibers produced by DMF-based one-step electrospinning, and (b) is a BET diagram of Pt-WO3 nanofibers produced by water-based one-step electrospinning.

[0024] Figure 5 These are gas-sensing test charts of the Pt-WO3 nanofiber sensor described in this embodiment of the invention for acetone. (a) is a cyclic test chart at a concentration of 1.8 ppm, (b) is a gradient concentration test chart, and (c) is a working temperature test chart.

[0025] Figure 6 These are further gas-sensing test diagrams of the water-based one-step electrospinning Pt-WO3 nanofiber sensor described in this embodiment of the invention. (a) is the response recovery time test diagram, (b) is the humidity resistance test diagram, (c) is the gas selectivity test diagram, and (d) is the long-term stability test diagram. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments, but is not limited thereto.

[0027] Example

[0028] (1) Preparation of precursor solution: Weigh 0.5g of ammonium metatungstate hydrate and dissolve it in 5mL of deionized water. Stir for 3h at a stirring speed of 300rpm / min. Then add 0.56mL of chloroplatinic acid solution with a concentration of 10mmol / mL to the above mixture and continue stirring for 3h at a stirring speed of 300rpm / min. Finally, weigh 0.5g of polyvinylpyrrolidone (K88-96) and add it to the above mixture. Stir continuously for 12h at a stirring speed of 200rpm / min to obtain a clear and transparent precursor solution.

[0029] (2) Electrospinning: The above precursor solution was transferred to a 10mL plastic syringe and connected with a 22G steel needle; the distance between the needle and the aluminum foil on the collecting side receiver was adjusted to 17cm, and the electrospinning parameters were adjusted: positive high voltage was 11kV, negative high voltage was 2.3kV, the extrusion speed of the spinneret was 0.7mL / h, the temperature of the electrospinning machine was 30℃, and the humidity was 50% to obtain the precursor fiber.

[0030] (3) Preparation of nanofibers: The precursor fibers obtained above were placed in a vacuum drying oven and dried at a temperature of 60°C for 24 hours. Then the dried precursor was cut into small pieces with scissors and calcined in a tube furnace at a temperature of 500°C for 2 hours with a heating rate of 2°C / min. After naturally cooling to room temperature, the obtained nanofibers were collected.

[0031] (4) Preparation of gas sensor: Weigh 15g of the prepared Pt-WO3 nanofiber sample, place it in an agate mortar, add 80μL of ethanol, grind it thoroughly until a paste is formed, and coat it on an alumina ceramic substrate with Au interdigitated electrodes deposited on the surface; then place the prepared gas sensor in an oven, set the drying temperature to 60℃, and the drying time to 24h to achieve the purpose of aging.

[0032] Comparative Example

[0033] In comparison, the 5 mL deionized water in the example was replaced with 5 mL N,N-dimethylformamide, while keeping all other conditions the same, to prepare a gas sensor based on Pt-WO3 nanofiber material using a DMF-based one-step electrospinning method.

[0034] Material characterization:

[0035] (1) After grinding the above Pt-WO3 nanofiber material, XRD tests were performed, such as... Figure 1 As shown, the results indicate that the Pt-WO3 materials prepared using deionized water and N,N-dimethylformamide as electrospinning precursor solvents, respectively, are all monoclinic WO3. The Pt-WO3 nanofibers obtained by the water-based one-step electrospinning method exhibit lower XRD peak sharpness, which is related to their greater number of lattice oxygen defects. These lattice oxygen defects, forming oxygen vacancies, can regulate carrier concentration, increase the active sites for gas adsorption and reaction, and thus enhance their gas sensing performance.

[0036] (2) The above Pt-WO3 nanofiber material was subjected to SEM testing, such as... Figure 2-3As shown, the results indicate that the Pt-WO3 materials prepared using deionized water and N,N-dimethylformamide as electrospinning precursor solvents, respectively, all exhibit a one-dimensional nanofiber structure, with the fibers composed of numerous WO3 crystallites and Pt metal loading on the fiber surface. However, the Pt-WO3 nanofibers obtained by the water-based one-step electrospinning method have a larger diameter and more fine WO3 crystallites on each fiber, increasing the specific surface area of ​​the material and providing more adsorption sites for gas adsorption.

[0037] (3) The above Pt-WO3 nanofiber material was subjected to BET testing, such as... Figure 4 As shown, the results indicate that the Pt-WO3 nanofibers obtained by the water-based one-step electrospinning method have a larger specific surface area and a smaller average pore size, which is more conducive to gas adsorption and desorption.

[0038] Gas Sensitivity Test:

[0039] (1) The prepared gas sensor was subjected to gas sensitivity testing using an intelligent gas-sensitive analysis system (CGS-MT miniature multifunctional detector station). Dynamic gas distribution was achieved using an automatic humidity-controlled gas-liquid distribution system (DGL-V), with humidity dynamically controlled by a dual-flow dynamic humidity generator (DHD-Ⅱ). A suitable amount of air with a specific humidity level and a mixture of acetone and air were alternately introduced into the chamber. During the test, the gas sensor was placed in the center of a heated Ag stage, heated to 300℃ and maintained until its ground-state resistance stabilized. Then, a gas circulation test was performed.

[0040] (2) Further, the response value of the gas sensor is defined as the ratio of the resistance Ra in the air background to the resistance Rg in the target gas acetone environment, and the response time and recovery time of the gas sensor are defined as the time required for the resistance value to change to 90% during the response and recovery process.

[0041] (3) The above-mentioned Pt-WO3 nanofiber sensor was used to perform gas-sensing tests on the target gas acetone, such as... Figure 5 As shown, the results indicate that at the optimal operating temperature of 300℃, the performance of the Pt-WO3 nanofiber sensor obtained by the water-based one-step electrospinning method is significantly better than that of the sensor obtained by the DMF-based one-step electrospinning method. This is because the Pt-WO3 nanofiber material obtained by the water-based one-step electrospinning method has more oxygen vacancies and a larger specific surface area, which regulates the carrier concentration and provides more active adsorption sites for the chemical adsorption of oxygen and target gases, thus being more conducive to improving the gas sensing performance.

[0042] (4) Further gas-sensing tests were conducted on the Pt-WO3 nanofiber sensor obtained by the water-based one-step electrospinning method, such as... Figure 6As shown, the results indicate that the sensor has a fast response recovery time, good humidity relationship, excellent selectivity, and long-term stability.

[0043] This invention discloses a Pt-WO3 nanofiber material based on a water-based one-step electrospinning method, its preparation method, and a gas sensor. The material uses H2O as a solvent and is prepared via a special water-based electrospinning method, exhibiting a one-dimensional nanofiber structure that facilitates electron conduction. Compared to materials obtained by traditional DMF-based electrospinning, it possesses abundant oxygen vacancies and a larger specific surface area, allowing for the regulation of carrier concentration and providing more active adsorption sites for the chemical adsorption of oxygen and target gases, thus enhancing gas-sensing performance. Furthermore, the surface-modified Pt exhibits catalytic and spillover effects, while simultaneously forming a Schottky barrier with WO3, generating a depletion layer and enhancing the gas-sensing response. The sensor demonstrates high sensitivity and selectivity for low-concentration acetone gas, with short response and recovery times and excellent long-term stability, showing great promise for applications in acetone-based breath analysis for diabetes diagnosis and industrial detection of low-concentration acetone gas.

[0044] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing Pt-WO3 nanofiber materials based on a water-based one-step electrospinning method, characterized in that, Includes the following steps: Ammonium metatungstate hydrate, chloroplatinic acid solution, polyvinylpyrrolidone, and water were mixed and dissolved to obtain a precursor solution; the mass ratio of ammonium metatungstate hydrate, polyvinylpyrrolidone, and water was 1:0.8~1.2:8~10; the volume ratio of chloroplatinic acid solution to water was 1:5~15, wherein the concentration of chloroplatinic acid solution was 10 mmol / mL; Precursor fibers are obtained by electrospinning the precursor solution; wherein the electrospinning parameters are: positive high voltage of 10~15 kV, negative high voltage of 1~3 kV, extrusion speed of the spinneret of 0.5~0.8 mL / h, distance between the spinneret and the receiver on the collection side of 14~20 cm, electrospinning machine temperature of 30~60℃, and humidity of 30%~60%; Pt-WO3 nanofiber material is obtained by drying and high-temperature calcination of precursor fibers; the drying temperature is 50~80℃ and the time is 12~36 h; the calcination temperature is 400~600℃ and the time is 1~3 h, with a heating rate of 1~3 ℃ / min.

2. A Pt-WO3 nanofiber material, characterized in that, The nanofibers prepared by the method as described in claim 1 are composed of WO3 grains and Pt is loaded on the surface of the nanofiber material.

3. A gas sensor, characterized in that, The Pt-WO3 nanofiber material as described in claim 2 is used as the sensitive layer material.

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