A porous hollow spherical PrFeO3 gas-sensitive material and its application

Abstract

The present invention discloses a porous hollow spherical PrFeO3 gas-sensitive material and its application. The porous hollow spherical PrFeO3 gas-sensitive material is prepared by placing Pr(NO3)3, Fe(NO3)3, CTAB, NH3·H2O, and deionized water in a beaker to obtain a mixed solution, allowing the mixed solution to stand, then stirring and heating in a water bath to obtain a mixed sol; pre-sintering the mixed sol, then grinding it, and then sintering it to obtain porous hollow spherical PrFeO3 powder. The PrFeO3 powder is mixed with deionized water to form a paste, which is then coated on the outer wall of the middle portion of a ceramic tube to prepare a sensor. The present invention utilizes a cationic surfactant CTAB-assisted synthesis method to prepare porous hollow spherical PrFeO3 with a high specific surface area and high porosity. The material exhibits an extremely high response to CH3SH gas and can be used for the non-invasive diagnosis of periodontitis by detecting low concentrations of CH3SH.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor gas-sensitive materials, and in particular to a porous hollow spherical PrFeO3 gas-sensitive material and applications thereof. Background Art

[0002] CH₃SH is a colorless, toxic, and flammable acidic gas. It is a typical hazardous gas with a distinctive odor, and even low concentrations can impair the human sense of smell. CH₃SH is released during the decomposition of food and is the cause of bad breath associated with periodontitis. The exhaled breath of periodontitis patients contains approximately 54 ppb of CH₃SH, while that of healthy individuals is approximately 17.2 ppb. Using the nose to detect CH₃SH can be fatal. Therefore, timely detection of extremely low concentrations of CH₃SH is essential and crucial.

[0003] In recent years, the use of MOS (metal oxide semiconductor) gas sensors to detect target gas concentrations has become increasingly popular. Examples include smoke sensors in hotels and natural gas alarms in homes. Reports indicate that some MOS materials, such as LaFeO3, SmFeO3, PrFeO3, HoFeO3NdFeO3, YCoO3, BaSnO3, ZnSnO3, and YMnO3, exhibit excellent gas response. Gas-sensing materials capable of detecting CH3SH include BaSnO3, Pd-SnO2, WO3, V2O5 / WO3 / TiO2, Au-WO3, LaFeO3, MFe2O4, and ZnO. MOS materials, particularly ABO3 perovskite materials, possess the unique advantages of large surface area and abundant active sites, which facilitate diffusion pathways, increase adsorption of target gas molecules, and thus enhance sensing capabilities. Although there have been many reports on gas sensors for detecting CH3SH, the detection performance of gas-sensitive materials for CH3SH is generally not good enough, and the detection limit does not reach the PPB level, which is a challenge to practical requirements. Summary of the Invention

[0004] In response to the above-mentioned prior art, the present invention aims to provide a porous hollow spherical PrFeO3 gas-sensitive material and its applications. This material, synthesized using a cationic surfactant CTAB-assisted method, produces porous hollow spherical PrFeO3 with high surface area and porosity. These materials exhibit a high response to CH3SH gas, and their detection of low-concentration CH3SH can be used for noninvasive diagnosis of periodontitis.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a method for preparing a porous hollow spherical PrFeO3 gas-sensitive material, comprising the following steps:

[0007] (1) Pr(NO3)3, Fe(NO3)3, CTAB (cetyltrimethylammonium bromide), NH3·H2O, and deionized water are placed in a beaker to obtain a mixed solution, the mixed solution is allowed to stand, and then placed in a water bath with stirring and heating to obtain a mixed sol;

[0008] (2) The mixed sol is pre-sintered, then ground, and then sintered to finally obtain PrFeO3 powder, that is, porous hollow spherical PrFeO3 gas-sensitive material.

[0009] Preferably, in step (1), the mass ratio of Pr(NO3)3, Fe(NO3)3, CTAB, NH3·H2O and deionized water is 32.69:24.185:10:10:100.

[0010] Preferably, in step (1), the standing is standing at room temperature for 2 hours; the temperature for stirring and heating in a water bath is 80° C., and the time for stirring and heating in a water bath is 24 hours.

[0011] Preferably, in step (2), the pre-sintering temperature is 100° C. and the time is 2 hours.

[0012] Preferably, in step (2), the grinding time is 1 to 3 hours; the sintering temperature is 800° C. and the sintering time is 6 hours.

[0013] The second aspect of the present invention provides a porous hollow spherical PrFeO3 gas-sensitive material prepared by the above preparation method.

[0014] Preferably, the average particle size of the porous hollow spherical PrFeO3 gas-sensitive material is 62.7 nm, and the specific surface area is 46.32 m 2 / g.

[0015] The third aspect of the present invention provides the use of porous hollow spherical PrFeO3 gas-sensitive material in the preparation of gas sensors.

[0016] A fourth aspect of the present invention provides a sensor for detecting CH3SH, which is prepared by the following method:

[0017] A porous hollow spherical PrFeO3 gas-sensitive material is mixed with deionized water to form a paste, which is then coated on the outer wall of a ceramic tube in the middle to form a sensing membrane. Electrodes are provided at both ends of the sensing membrane. The ceramic tube is heated using a nickel-chromium wire. The Au electrode is connected to a Pt wire to detect the resistance of the sensing membrane. After aging, the above device is used to obtain a sensor.

[0018] Preferably, in the paste, the concentration of the porous hollow spherical PrFeO3 gas-sensitive material is 20 g / L; the aging temperature is 200° C., and the aging time is 24 h.

[0019] A fifth aspect of the present invention provides use of a sensor in detecting CH3SH or non-invasively diagnosing periodontitis.

[0020] Beneficial effects of the present invention:

[0021] (1) The present invention uses a cationic surfactant CTAB (cetyltrimethylammonium bromide)-assisted method to prepare porous hollow spherical PrFeO3. Compared with undoped CTAB, the porous spherical PrFeO3 prepared in the present invention has a relatively fast reaction / recovery time at 260°C, significantly improved reaction efficiency, and higher selectivity for CH3SH.

[0022] (2) The average error in CH₃SH detection using the porous spherical PrFeO₃ prepared by the present invention compared to GC-MS detection of CH₃SH was less than 10%. These experimental results fully demonstrate the advantages of high specific surface area in improving the performance of gas-sensing materials and the great potential of porous spherical PrFeO₃ for CH₃SH detection. Compared with pure PrFeO₃, the response recovery time of the PrFeO₃ prepared by the present invention was shortened by 2 times, and two important properties, RH adaptability and selectivity, were also improved.

[0023] (3) The gas-sensitive material prepared by the present invention has high response, high selectivity, low detection limit, and high long-term stability; the method for preparing the sensor is simple and low-cost, and can be used for extremely low concentration CH3SH detection or non-invasive diagnosis of periodontitis. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 :(a) Gas sensor structure diagram; (b) Gas sensor test system circuit diagram.

[0025] Figure 2 :(a) XRD pattern of PrFeO3; (b) EDS spectrum of PrFeO3; (cf) X-ray photoelectron spectroscopy (XPS) of PrFeO3; (c) XPS full spectrum scan; (d) Pr 3d; (e) Fe 2p; (f) O 1s.

[0026] Figure 3 :(ab) SEM images of PrFeO3 prepared in Example 1; (cd) SEM images of pure PrFeO3 prepared in Comparative Example 1; (e) N2 adsorption-desorption isotherm and pore size distribution of PrFeO3 powder (in the figure); (f) Specific surface area of PrFeO3 under different preparation conditions.

[0027] Figure 4: (a) Response of PrFeO3 prepared in Example and Comparative Example 1 to 1 ppm CH3SH; (b) Linear relationship between the response and CH3SH concentration.

[0028] Figure 5 : (a) Dynamic response of PrFeO3 prepared in Example to different concentrations of CH3SH; (b) Dynamic response of pure PrFeO3 prepared in Comparative Example 1 to different concentrations of CH3SH; (c) Response and recovery time of PrFeO3 prepared in Example at different temperatures (d) Response and recovery time of pure PrFeO3 prepared in Comparative Example 1 at different temperatures.

[0029] Figure 6 Comparison of the selectivity of PrFeO3 prepared in Example (a) and Comparative Example 1 (b) to 1 ppm CH3SH and human exhaled gas.

[0030] Figure 7 :(a) Response curve of PrFeO3 with RH; (b) Resistance curve of PrFeO3 with RH; (c) Response curve of PrFeO3 with time.

[0031] Figure 8 :The present invention studies the reaction mechanism of the entire experiment, including: (a) the charge state of the material surface at room temperature; (b) the charge state of the material surface at high temperature; (c) the resistance variation curve of PrFeO3 prepared in the embodiment as a function of operating temperature; (d) the change of the charge state of the material surface after injection of the target gas at high temperature; (e) the change of the charge state of the material surface as a function of gas concentration at high temperature. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0033] As mentioned in the background technology section, MOS materials, particularly ABO3 perovskite materials, offer the unique advantages of large surface area and abundant active sites, which can facilitate diffusion pathways and enhance the adsorption of target gas molecules. Materials such as LaFeO3 and PrFeO3 can detect CH3SH, but these materials have limited detection capabilities for low-concentration CH3SH, with detection limits falling short of PPB levels.

[0034] Based on this, the present invention aims to provide a porous hollow spherical PrFeO3 gas-sensing material and its application. This material is synthesized using a cationic surfactant CTAB-assisted method and sintered at 800°C to produce porous hollow spherical PrFeO3 with high specific surface area and high porosity. These porous hollow spherical PrFeO3 exhibit high specific surface area and high porosity, two important factors that enhance the gas-sensing material's response to target gases. The porous spherical PrFeO3 exhibits extremely high gas response and selectivity for CH3SH.

[0035] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments.

[0036] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0037] Example

[0038] (1) Preparation of porous hollow PrFeO3

[0039] Pr(NO₃)₃, Fe(NO₃)₃, CTAB, NH₃·H₂O, and deionized water were placed in a beaker at a mass ratio of 32.69:24.185:10:10:100 to obtain a mixed solution. The mixed solution was allowed to stand for 2 hours, then stirred in a water bath at 80°C for 24 hours to obtain a mixed sol. The mixed sol was then pre-sintered in a muffle furnace at 100°C for 2 hours. After cooling, the solution was ball-milled in a planetary mill for 1 hour, followed by sintering in a muffle furnace at 800°C for 6 hours to obtain PrFeO₃ powder.

[0040] Figure 2 a is the X-ray diffraction analysis of PrFeO3 prepared in this example (XRD, Bruker D8ADVANCE, CuKα content is Compared to a standard card (PDF card: 47-0065) at 40 kV and 40 mA, it shows a single phase. The average particle size can be calculated using the Scheele method. The Scheele equation is as follows:

[0041] D=kλ / βcosθ

[0042] Where λ is the wavelength of the X-ray, β is the integral width of the diffraction peak, and θ is the Bragg diffraction angle. The average particle size of PrFeO3 is about 62.7nm.

[0043] The PrFeO3 prepared in this example was subjected to energy spectrum analysis to confirm that there were no other elements in the material. Figure 2b It can be seen that there are only Pr, Fe and O elements in the material. X-ray photoelectron spectroscopy (XPS, Thermo ScientificTMK-AlphaTM+ spectrometer, equipped with a monochromatic Al KαX-ray source (1486.6eV), power: 100W) was used to determine the valence state of the elements in PrFeO3 ( Figure 2 c). It was observed that the material contained Pr, Fe and O elements.

[0044] (2) Preparation of sensor

[0045] The PrFeO3 powder prepared in the example was mixed with deionized water to form a paste. The paste was coated on the outer wall of the middle part of the ceramic tube to form a sensing film. The resistance of the sensing film was monitored in real time using an Au electrode and a Pt wire. The ceramic tube had an outer diameter of about 2 mm, a length of about 8 mm, and an inner diameter of about 1.6 mm. A nickel-chromium wire was used to heat the ceramic tube to a higher operating temperature ( Figure 1 a) Place the prepared sensor on an aging table and age it at 200°C for 24 hours. Then, test the prepared sensor with the target gas in a gas sensor testing system.

[0046] The test circuit of the gas sensor test system is as follows Figure 1 b. Where Vp is the supply voltage, which is always 5V, Vp is the value of the variable resistor; ower R0V0 is the voltage across; R0v sensor is the voltage across the gas sensor; R sensor Calculated by the following formula:

[0047]

[0048] The gas response S is defined as R g / R a R a It is the resistance of the sensor in the air and the resistance in the measured gas. g Response time is defined as the time required for the rising phase to reach 90% of the maximum value, and recovery time is defined as the time required for the falling phase to return to 10% of the baseline value. Experimental environment: RH: 20%; ambient temperature: 20°C.

[0049] Comparative Example 1

[0050] The difference from the embodiment is that CTAB is not added and pure PrFeO3 is prepared.

[0051] Comparative Example 2

[0052] The difference from the embodiment is that the PrFeO3 powder is finally obtained by sintering at 700°C in a muffle furnace for 6 hours.

[0053] Comparative Example 3

[0054] The difference from the embodiment is that the PrFeO3 powder is finally obtained by sintering at 900°C in a muffle furnace for 6 hours.

[0055] Figure 3 ab are electron microscope images of PrFeO3 prepared in Example. It can be seen from the figure that the PrFeO3 prepared in Example has a porous spherical structure with uniform particle size and hollow interior, which increases the specific surface area and the circulation channels of gas molecules, thereby showing higher gas sensitivity. Figure 3 cd is PrFeO3 prepared in comparative example 1, which presents a common perovskite structure, with uneven particle size, few gaps between particles, small specific surface area, few molecular circulation channels, and low gas sensitivity.

[0056] The specific surface area and porosity of PrFeO3 were further analyzed by nitrogen adsorption-desorption method. Figure 3 It can be seen from e that the specific surface area of PrFeO3 prepared in Example is 46.32m 2 In addition, in Example 2 and Comparative Examples 2-3, PrFeO3 ( Figure 3 f). It can be seen that the specific surface area of PrFeO3 with the addition of CTAB during the preparation process is higher than that of PrFeO3 without the addition of CTAB, among which the PrFeO3 prepared in Example has the highest specific surface area.

[0057] The response curves of PrFeO3 prepared in Example and Comparative Example 1 to 1ppm CH3SH are shown in FIG. Figure 4 . The PrFeO3 prepared in Example and Comparative Example 1 has the highest response at 260°C. The highest response of 1ppm CH3SH is 66.28 (Example) and 11.38 (Comparative Example 1), respectively. The response speed of PrFeO3 prepared in Example is nearly 6 times that of Comparative Example 1. The relationship between the sensitivity of the material and the gas concentration is very important, and a high fitting relationship can be used to predict the response value at a given gas concentration. The response of PrFeO3 prepared in Example and Comparative Example 1 shows a good linear relationship with the gas concentration, R 2 The values are all greater than 95%.

[0058] Test example

[0059] 1. Repeatability test

[0060] Repeatability is another important characteristic that determines whether a gas-sensitive material is good. For PrFeO3, the repeatability of the response to CH3SH gas at different concentrations is as follows: Figure 5As shown in ab. All repeated processes are as follows: When the resistance value of the gas-sensitive material stabilizes, CH3SH gas is injected into the reaction chamber, and the resistance of the material increases immediately. After a period of time, the resistance stabilizes, and then the CH3SH gas is removed, and the resistance of the material immediately drops and can be restored to its initial state. For different concentrations of CH3SH gas, the resistance of the gas-sensitive material can be restored to the initial value each time the CH3SH gas is removed, indicating that the material has good repeatability. Under different operating temperatures, the response and recovery time of PrFeO3 prepared in Example 1 and Comparative Example 1 are different, indicating that the operating temperature will affect the chemical reaction on the surface of the material. The response recovery time of PrFeO3 prepared in Example 1 and Comparative Example 1 is shown in FIG. Figure 5 As shown in cd. Before 260°C, the response and recovery time increase with the increase of operating temperature. After 260°C, the response and recovery time decrease with the further increase of operating temperature. This may be because before the optimal operating temperature, the adsorption rate of gas molecules is higher than the desorption rate, and the number of oxygen ions and CH3SH gas molecules adsorbed on the surface of the material increases, resulting in an increase in reaction time. As the operating temperature increases, the adsorption rate and desorption rate remain balanced at the optimal operating temperature, and the number of CH3SH gas molecules and the number of oxygen ions adsorbed on the surface of the material reach a maximum value. At this operating temperature, the reaction time also reaches a maximum value. As the operating temperature further increases, the desorption rate of gas molecules is higher than the adsorption rate, the reactants become less, and the reaction time becomes shorter. In addition, compared with the PrFeO3 prepared in Comparative Example 1, the response and recovery time of PrFeO3 prepared in Example 1 is shortened by 2 times.

[0061] 2. Selective testing

[0062] In practical applications, it is very common to detect a certain gas in a mixture, especially CH3SH gas exhaled by real people. Therefore, the selectivity of a gas-sensitive material to a certain gas determines its practical application value. The selectivity of PrFeO3 prepared in Example 1 and Comparative Example 1 to 1ppm CH3SH and several other common gases exhaled by humans is shown in the figure below. Figure 6 As shown in ab. Compared with other gases, the PrFeO3 prepared in this example has a high selectivity for CH3SH. In particular, the response to common gases such as N2, O2, NO, CO2, and CO exhaled by humans is negligible, thereby more accurately detecting CH3SH in human exhaled air.

[0063] 3. Stability test

[0064] The relative humidity (RH) in the environment is also a factor that cannot be ignored in gas sensor applications. Figure 7Figure a shows the response of PrFeO3 prepared in Example 1 and Comparative Example 1 to 1 ppm CH3SH under different relative humidity (RH). The response decreases with increasing RH, indicating that the gas sensor of the present invention can be used in low-RH environments without considering the influence of RH. This will greatly expand its practical application. Figure 7 Figure b shows the resistance of PrFeO3 prepared in Example and Comparative Example 1 as a function of RH. For PrFeO3, the resistance decreases with increasing RH, but the rate of decrease varies. Within the RH range of 20% to 90%, the decrease is 44.32% (Example) and 75.73% (Comparative Example 1). This indicates that the resistance of PrFeO3 prepared in Example exhibits the highest RH adaptability. Relative humidity also affects the response of gas-sensitive materials to target gases.

[0065] Long-term stability is another important characteristic of gas-sensing materials. The higher the long-term stability of gas-sensing materials, the longer the replacement cycle, the greater the economic and energy advantages. Figure 7 C is the long-term stability of PrFeO3 prepared in Example and Comparative Example 1 over 30 days. Experimental data were obtained every two days. All responses decreased slightly over time, but the rate of decrease was different. The rate of decrease was 2.61% (Example), 17.46% (Comparative Example 1). The long-term stability of PrFeO3 prepared in Example is more than 6 times that of PrFeO3 prepared in Comparative Example 1. PrFeO3 prepared in Example has a higher advantage in long-term stability.

[0066] 4. Sensing mechanism analysis

[0067] Figure 8 The reaction mechanism of the sensor prepared in the embodiment is shown. At room temperature (20°C), for p-type semiconductors, the main carriers of PrFeO3 are holes (h · )( Figure 8 a). According to the Kroger-Vink defect symbol, the vacancy is mainly composed of Ionization occurs, and the reaction may be like this:

[0068]

[0069] Oxygen molecules adsorbed on the surface of PrFeO3 continuously capture electrons from the material, resulting in an increase in the number of holes ( Figure 8 b). At room temperature, the rate at which oxygen molecules capture electrons is very low and has little effect on the resistance value. However, as the operating temperature gradually increases, the capture rate on the PrFeO3 surface increases. Therefore, the resistance decreases with increasing operating temperature ( Figure 8 c).

[0070] On the PrFeO3 surface, the reaction between oxygen molecules and free electrons is as follows:

[0071]

[0072]

[0073] ad represents the state of oxygen adsorption on the PrFeO3 surface.

[0074] After CH3SH gas molecules are introduced, they will be adsorbed on the surface of PrFeO3 and react with oxygen ions ( Figure 8 d). The adsorption and desorption of CH3SH gas molecules on the PrFeO3 surface exist simultaneously. The adsorption and desorption rates increase with the increase of operating temperature, and the adsorption rate is greater than the desorption rate before the operating temperature reaches the optimal temperature. Therefore, the number of CH3SH molecules adsorbed on the material surface increases, and the reaction of CH3SH molecules with oxygen ions becomes more intense, resulting in an increase in response. When the operating temperature exceeds the optimal temperature, the adsorption rate of CH3SH molecules on PrFeO3 is lower than the desorption rate, and the reaction intensity of CH3SH molecules with oxygen ions decreases, resulting in a decrease in response. In addition, at the optimum temperature, as the concentration of CH3SH gas molecules increases, the number of CH3SH molecules adsorbed on the PrFeO3 surface increases, resulting in an increase in response ( Figure 8 e). However, the number of free electrons on the surface of PrFeO3 is not infinite, and the energy required for electron transition inside PrFeO3 is also increasing. Therefore, the response (R g / R a ) increases with the increase of CH3SH gas molecule concentration, but the increasing rate decreases.

[0075] The reaction between CH3SH molecules and oxygen ions is as follows:

[0076]

[0077] e - +h + →null

[0078] Application Examples

[0079] Oral halitosis is a common oral disease, closely related to the breakdown of proteins by oral anaerobic bacteria and the production of volatile sulfide compounds (VSCs). The production of oral VSCs is closely linked to the development of periodontitis. Clinically, patients with periodontitis often experience varying degrees of halitosis. The periodontal pocket is a key site for the production of volatile sulfide compounds (VSCs), with CH₃SH being the most important component. It has been reported that the concentration of CH₃SH in the exhaled breath of periodontitis patients differs significantly from that of healthy individuals. Therefore, the concentrations of these two gases in exhaled breath can be used to determine whether a person has or is at risk of developing periodontitis. However, the response of PrFeO₃ to 40,000 ppm CO₂ cannot be ignored, as this is the approximate concentration of CO₂ in human exhaled breath. The response to 40,000 ppm CO₂ is subtracted from the response to human exhaled breath, and the resulting value is considered the response to CH₃SH.

[0080] Table 1 shows the CH3SH concentrations in the exhaled breath of four volunteers, obtained using the PrFeO3 gas sensor prepared in the examples and GC-MS. To mitigate the effects of age, gender, and other factors on the results, 40-year-old volunteers, half male, half female, and half healthy, were used as controls. Volunteers 1 and 2 were patients with periodontitis, and the other two volunteers served as healthy controls. The response to carbon dioxide has been subtracted from the response values. Comparing the CH3SH concentrations measured by the two methods, the maximum error did not exceed 14%, and the average error did not exceed 10%. Furthermore, at all times, the CH3SH concentration measured by the PrFeO3 gas sensor prepared in the examples was greater than that measured by GC-MS, indicating the presence of other gases in human exhaled breath. The experimental results confirm that the concentration of CH3SH gas in human exhaled breath can be measured, and the difference in concentrations can be used as a biomarker to distinguish between healthy and periodontitis patients, or to prevent the onset of periodontitis.

[0081] Table 1. Concentration of CH3SH measured using a PrFeO3 gas sensor and gas chromatography-mass spectrometry.

[0082]

[0083] The PrFeO3 prepared by the present invention is synthesized using a cationic surfactant CTAB-assisted method and sintered at 800°C. Under a scanning electron microscope, it presents porous hollow spheres with a large specific surface area and high porosity, which greatly improves the response. Compared with the PrFeO3 in comparative example 1 without the addition of CTAB, the response to CH3SH gas is now nearly 6 times higher. In addition, the response recovery time of PrFeO3 is shortened by 2 times, and two important characteristics, such as RH adaptability and selectivity, are also improved. Finally, the PrFeO3 sensor prepared by the present invention is very accurate in detecting the concentration of CH3SH gas in human exhaled gas, with a quiet error of less than 10% compared with gas chromatography-mass spectrometry. The experimental results fully demonstrate the advantages of the high specific surface area and high porosity of PrFeO3 in improving the performance of gas-sensitive materials, as well as its great potential in CH3SH detection.

[0084] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. Application of a porous hollow spherical PrFeO3 gas-sensitive material in detecting CH3SH, characterized in that: The preparation method of the porous hollow spherical PrFeO3 gas-sensitive material is as follows: (1) Pr(NO3)3, Fe(NO3)3, CTAB, NH3•H2O and deionized water were placed in a beaker to obtain a mixed solution, the mixed solution was allowed to stand, and then placed in a water bath with stirring and heating to obtain a mixed sol; (2) Pre-sintering the mixed sol, then grinding it, and then sintering it to finally obtain PrFeO3 powder, i.e., porous hollow spherical PrFeO3 gas-sensitive material; A porous hollow spherical PrFeO3 gas-sensitive material is mixed with deionized water to form a paste, which is then coated on the outer wall of the middle part of a ceramic tube to form a sensing membrane. Electrodes are provided at both ends of the sensing membrane. The electrodes are Au electrodes connected to a Pt wire to detect the resistance of the sensing membrane. The ceramic tube is heated using a nickel-chromium wire. After aging, a sensor is obtained.

2. The use according to claim 1, characterized in that The concentration of the porous hollow spherical PrFeO3 gas-sensitive material in the paste is 20 g / L; the aging temperature is 200° C. and the aging time is 24 h.

3. The use according to claim 1, characterized in that In step (1), the mass ratio of Pr(NO3)3, Fe(NO3)3, CTAB, NH3•H2O and deionized water is 32.69:24.185:10:10:

100.

4. The use according to claim 1, characterized in that In step (1), the standing is standing at room temperature for 2 hours; the temperature of stirring and heating in the water bath is 80° C., and the time of stirring and heating in the water bath is 24 hours.

5. The use according to claim 1, characterized in that In step (2), the pre-sintering temperature is 100°C and the time is 2 hours; the grinding time is 1 to 3 hours; and the sintering temperature is 800°C and the time is 6 hours.

6. The use according to claim 1, characterized in that The average particle size of the porous hollow spherical PrFeO3 gas-sensitive material is 62.7 nm, and the specific surface area is 46.32 m 2 / g.

Images