Ag / Pd-LaFeO3-based gas sensing material and application thereof in detection of hydrogen sulfide gas in municipal sewage

Abstract

The invention discloses a gas sensing material based on Ag / Pd-LaFeO3 and application of the gas sensing material in detection of hydrogen sulfide gas in municipal sewage, and relates to the technical field of gas sensing materials. The chemical formula of the gas sensing material based on Ag / Pd-LaFeO3 is X wt% of Ag-Y wt% of Pd-LaFeO3, wherein 0 lt; x < = 5, 0lt; y < = 5. According to the invention, on the basis of LaFeO3, the humidity interference resistance of the gas sensing material based on Ag / Pd-LaFeO3 can be improved through double noble metal surface modification of Ag and Pd. In addition, through double noble metal doping of Ag and Pd, the response sensitivity and selectivity of the prepared gas-sensitive material to H2S gas can be improved, and the working temperature of the gas-sensitive material is reduced. Specifically, at the working temperature of 110 DEG C, the response value of the prepared double noble metal modified LaFeO3 to 1ppm H2S gas is 46.16.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-sensitive materials, in particular to a gas sensing material based on Ag / Pd-LaFeO3 and an application thereof in detecting hydrogen sulfide gas in municipal sewage. Background Art

[0002] Because sewage in urban drainage pipes contains large amounts of sulfate and small amounts of organic sulfides, sulfate-reducing bacteria (SRB) convert these into sulfides, which are ultimately released as hydrogen sulfide. H2S is not only extremely corrosive to the steel and concrete structures of underground pipe networks, causing damage to municipal pipe networks and related facilities, but also poses a serious threat to the health and safety of operations personnel. The human olfactory threshold for H2S is approximately 10 ppm. Exceeding 110 ppm can cause olfactory paralysis or even acute poisoning, and concentrations exceeding 700 ppm can be fatal within a short period of time. Furthermore, H2S can form explosive mixtures with air, further increasing the safety risks of municipal sewage environments.

[0003] Currently, available H2S detection methods include electrochemical sensors, gas chromatography, optical sensors, and semiconductor gas sensors. Electrochemical sensors have a limited service life, are susceptible to cross-interference, and are affected by temperature and humidity, requiring regular calibration and replacement. Gas chromatography and optical sensors offer extremely high detection accuracy, but the equipment is expensive and analysis times are long, making them inadequate for real-time on-site monitoring. Semiconductor gas sensors, with their advantages of low cost, ease of integration, and rapid response recovery, are considered a key development direction for online H2S monitoring in municipal wastewater environments. However, existing semiconductor sensors still face technical bottlenecks such as decreased sensitivity, insufficient selectivity, and weak anti-interference capabilities in complex environments such as high humidity and high corrosion.

[0004] In the prior art, CN115128136A discloses a Pd-LaFeO3 gas-sensitive material for detecting hydrogen sulfide and its application. Specifically, a 3wt% Pd-LaFeO3 gas-sensitive material is synthesized using a sol-gel method. Pd doping can increase the surface activity of the gas-sensitive material and shorten the response recovery time. Its response value to 1.0ppm of H2S gas at 120°C is 36.29. The relative humidity (RH) of the environment is a key factor affecting the performance of gas-sensitive materials. When gas-sensitive materials are used to detect hydrogen sulfide in environmental wastewater, they are required to have excellent resistance to environmental humidity interference. However, the Pd-LaFeO3 gas-sensitive material in the aforementioned patent has a response value fluctuation of only 5% within the RH range of 20-40%. Therefore, the gas-sensitive material prepared by doping LaFeO3 with Pd alone has poor resistance to humidity interference and is not suitable for detecting hydrogen sulfide gas in wastewater.

[0005] Therefore, it is particularly necessary to dope and modify LaFeO3 materials to prepare a gas-sensitive material with good anti-humidity interference performance for the detection of H2S in municipal sewage. Summary of the Invention

[0006] In view of the above-mentioned prior art, the object of the present invention is to provide a gas-sensing material based on Ag / Pd-LaFeO3 and its application in the detection of hydrogen sulfide gas in municipal sewage. The chemical formula of the gas-sensing material based on Ag / Pd-LaFeO3 is X wt% Ag - Y wt% Pd-LaFeO3, where 0 < X ≤ 5 and 0 < Y ≤ 5. Based on LaFeO3, through the surface modification of double noble metals Ag and Pd, the anti-humidity interference performance of the gas-sensing material based on Ag / Pd-LaFeO3 can be improved. In addition, the response sensitivity and selectivity of the prepared gas-sensitive material to H2S gas can be improved and its working temperature can be reduced by doping with double noble metals Ag and Pd. Specifically, at a working temperature of 110 °C, the response value of the double noble metal-modified LaFeO3 prepared by the present invention to 1 ppm H2S gas is 46.16.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In the first aspect of the present invention, a gas-sensing material based on Ag / Pd-LaFeO3 is provided, and the chemical formula of the gas-sensing material is X wt% Ag - Y wt% Pd-LaFeO3;

[0009] In the formula, Xwt% is the doping amount of Ag in the gas-sensitive sensing material, and Ywt% is the doping amount of Pd in the gas-sensitive sensing material; 0 < X ≤ 5 and 0 < Y ≤ 5.

[0010] In the second aspect of the present invention, a preparation method of the above-mentioned gas-sensing material based on Ag / Pd-LaFeO3 is provided, including the following steps:

[0011] (1) Mix La(NO3)3·6H2O, Fe(NO3)3·9H2O, AgNO3 and PdCl2 and dissolve them in deionized water. After mixing evenly, a mixed solution is obtained; add citric acid and ethanol to the mixed solution and stir to obtain a sol;

[0012] (2) Heat the sol to age it to obtain a gel; dry the gel to obtain a dry gel; calcine the dry gel to obtain the gas-sensing material based on Ag / Pd-LaFeO3.

[0013] Preferably, the addition ratio of La(NO3)3·6H2O, Fe(NO3)3·9H2O, AgNO3, PdCl2, citric acid, ethanol and deionized water is (0.01–0.05) mol: (0.01–0.05) mol: (0.01–0.5) g: (0.01–0.5) g: (5–20) g: (5–15) mL: (50–150) mL.

[0014] Preferably, in step (1), the stirring time is 1-2 h.

[0015] Preferably, in step (2), the heating temperature is 70-90° C. and the heating time is 2-6 h.

[0016] Preferably, in step (2), the drying temperature is 60-80° C. and the drying time is 6 to 12 hours.

[0017] Preferably, in step (2), the calcination atmosphere is air atmosphere, the calcination temperature is 600-900° C., and the calcination time is 2-4 h.

[0018] The third aspect of the present invention provides the use of the above-mentioned Ag / Pd-LaFeO3-based gas sensing material in the following (1) or (2):

[0019] (1) H2S gas in municipal sewage environment;

[0020] (2) Preparation of H2S gas sensor.

[0021] Preferably, the municipal sewage environment includes municipal sewage pipes, pumping stations, and inspection wells.

[0022] Preferably, the concentration of H2S gas is 0.5-5 ppm.

[0023] Preferably, the H2S gas sensor is prepared by the following preparation method:

[0024] The Ag / Pd-LaFeO3-based gas sensing material, deionized water, and pinene alcohol were mixed in the ratio of (1-3) g: (5-10) mL: (1-3) mL to prepare a slurry. The slurry was spin-coated on an alumina ceramic substrate to form a gas-sensitive film with a thickness of 50-200 μm. The gas-sensitive film was aged at 180-200°C for 12-24 h to obtain an H2S gas sensor.

[0025] Preferably, the operating temperature of the H2S gas sensor is 60-200°C.

[0026] Beneficial effects of the present invention:

[0027] 1. The present invention uses dual precious metals Ag and Pd to uniformly dope the LaFeO3 matrix material to obtain a gas sensing material based on Ag / Pd-LaFeO3. The composite doping of Ag and Pd can improve the humidity interference resistance of the gas-sensitive material. This property makes the material well adaptable to environmental factors such as high humidity, high corrosion, and complex background gases in municipal sewage pipe networks, and can operate stably and long-term in high-humidity and high-corrosion scenarios such as municipal sewage pipes, pumping stations, and inspection wells. Specifically, the Ag / Pd-LaFeO3-based gas sensing material prepared by the present invention has a response value fluctuation of less than 5% under conditions of relative humidity less than 70%, showing excellent humidity interference resistance.

[0028] 2. The present invention uniformly dopes the LaFeO3 matrix material with dual precious metals Ag and Pd, which can significantly improve the catalytic activity and electron transfer efficiency of the gas-sensitive material, effectively reduce the adsorption and reaction energy barriers of H2S molecules, and not only improve the response sensitivity and selectivity of the gas-sensitive material to H2S gas, but also reduce the operating temperature of the gas-sensitive material. Specifically, the Ag / Pd-LaFeO3-based gas sensing material prepared by the present invention has a response value of 46.16 to 1ppm H2S gas at an operating temperature of 110°C. The gas sensing material prepared by the present invention has low overall energy consumption and fast response speed, and is easy to integrate into municipal online monitoring and intelligent early warning systems, greatly improving the early detection of toxic and harmful gas leaks in sewage pipe networks and the personal safety protection capabilities of operation and maintenance personnel.

[0029] 3. The Ag / Pd-LaFeO3-based gas sensing material, prepared by the sol-gel method, is nanoscale, possessing a rich specific surface area and uniform distribution of active sites. Its particle size ranges from 50 to 150 nm. The stable structure and uniform particle size of the gas sensing material ensure the long-term repeatability and reliability of the gas sensor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 : XRD pattern of the Ag / Pd-LaFeO3-based gas sensing material prepared in Example 1;

[0031] Figure 2 : SEM image of the Ag / Pd-LaFeO3-based gas sensing material prepared in Example 1;

[0032] Figure 3 : EDSMapping diagram of Ag, Pd and La elements in the Ag / Pd-LaFeO3-based gas sensing material prepared in Example 1;

[0033] Figure 4 : A graph showing the relationship between the gas-sensing performance of the gas-sensitive materials prepared in Example 1 and Comparative Examples 1-3 to 1 ppm H2S gas and temperature;

[0034] Figure 5 : Relationship graphs of the gas-sensing properties of the materials prepared in Example 1 and Comparative Examples 1-3 to 1 ppm H2S gas and humidity; wherein, (a) is a relationship graph of the gas-sensing properties of the material prepared in Example 1 to 1 ppm H2S gas and humidity; (b) is a relationship graph of the gas-sensing properties of the material prepared in Comparative Example 2 to 1 ppm H2S gas and humidity; (c) is a relationship graph of the gas-sensing properties of the material prepared in Comparative Example 3 to 1 ppm H2S gas and humidity; (d) is a relationship graph of the gas-sensing properties of the material prepared in Comparative Example 1 to 1 ppm H2S gas and humidity;

[0035] Figure 6 : Schematic diagram of the long-term gas-sensitive stability of the Ag / Pd-LaFeO3-based gas sensing material prepared in Example 1 to 1 ppm H2S gas. DETAILED DESCRIPTION

[0036] 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.

[0037] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0038] Prior art has disclosed that the perovskite-type p-type oxide LaFeO3 has been widely studied for detecting reducing gases (such as H2S) due to its stable structure, abundant oxygen vacancies, and adjustable valence state. Furthermore, there are also reports of modifying the LaFeO3 matrix material with a single precious metal, Pd, to increase the sensitivity and lower the operating temperature of the resulting gas-sensing material. However, relative humidity (RH) is a key factor affecting the performance of gas-sensing materials. These aforementioned gas-sensing materials have poor resistance to humidity interference and are therefore unsuitable for detecting hydrogen sulfide in wastewater.

[0039] Based on this, the present invention provides a gas sensing material based on Ag / Pd-LaFeO3 and its application in the detection of hydrogen sulfide gas in municipal sewage. By modifying or doping precious metal nanoparticles on the surface of LaFeO3, the Schottky barrier between the precious metal and the semiconductor can be used to regulate the carrier distribution. At the same time, the precious metal has a surface chemical sensitization effect, which can enhance the catalytic activity of the material to the target gas molecules, thereby improving the sensitivity and reducing the operating temperature. Silver (Ag) has excellent electron transfer ability, which helps to improve the conductivity and gas response rate of the material; palladium (Pd) has a low activation energy for the breaking of S-H bonds, which can promote the efficient catalytic oxidation of H2S molecules. Ag and Pd synergistically doping LaFeO3 is expected to achieve highly sensitive and selective detection of H2S at a lower operating temperature, and effectively suppress the response to interfering gases such as SO2 and NH3, thereby improving the detection accuracy and safety assurance capabilities in the municipal sewage environment.

[0040] Simultaneously doping Pd and Ag into LaFeO3 can produce a synergistic effect, significantly improving the material's performance in detecting H2S in a humid environment in many aspects.

[0041] First, in terms of material structure and electrical properties, dual doping introduces more heterogeneous interfaces and defects, which helps to optimize the ground-state conductivity and reaction activity of the sensing material. The coexistence of Pd and Ag will form dispersed PdO / Pd and Ag2O / Ag nanostructures on the LaFeO3 surface, each of which forms a Schottky barrier with the semiconductor matrix, and the superposition produces a more complex interface electronic control effect. The presence of space charge layers in these interface regions further reduces the hole concentration on the p-type LaFeO3 surface and improves the sensor's sensitivity to resistance changes. When H2S gas arrives, the barrier height at different interfaces will be adjusted due to changes in the atmosphere, causing the carriers to be redistributed, resulting in a drastic change in resistance. Dual metal doping is equivalent to establishing multiple electronic control channels in the material, providing more sensitive signal modulation capabilities than single doping. In addition, Pd and Ag are both low-valence doping elements, which replace Fe 3+ or La 3+ When Pd / Ag is added to the material, a large number of oxygen vacancies are introduced to maintain charge balance. The concentration and distribution of oxygen vacancies are further enhanced during dual doping, which not only facilitates the adsorption and activation of H2S but also provides adsorption sites for more oxygen molecules, thereby storing a higher concentration of active oxygen species on the material surface. In summary, the synergistic effects of Pd / Ag dual doping on lattice defects and interface energy levels significantly enhance the material's electrical conductivity control capabilities and sensitivity to gas reactions.

[0042] Secondly, in terms of surface chemical reaction and adsorption, the complementary functions of Pd and Ag further enhance the ability to resist humidity interference. Pd has excellent H2S molecular chemical adsorption and decomposition capabilities, and can dissociate H2S into active intermediates (such as HS, H, etc.) at low temperatures and oxidize them into sulfur oxides or elements on its surface. Ag is good at activating the surrounding oxygen, providing abundant O - / O 2- In the dual-doping system, H2S adsorbed on Pd rapidly reacts with oxygen species activated by Ag to form reaction products of water and sulfur, which release electrons and capture holes, significantly altering the resistance of LaFeO3. This "one-attract, one-donor" synergistic catalytic mechanism accelerates the reaction rate of the target gas and improves the sensitive response signal. Furthermore, dual-doping effectively suppresses the interference of water molecules on the sensing material surface. On the one hand, the Pd / Ag nanoparticle coating on the oxide surface makes it more difficult for water molecules to directly contact the sensitive sites on the LaFeO3 surface. Even if water vapor adsorbs, its binding to the noble metal surface is relatively weak, and the number of hydroxyl groups formed is limited, which does not significantly deplete the surface oxygen species. Furthermore, the synergistic effect of Pd / Ag enables the sensor to operate at a relatively high optimal operating temperature (compared to Pd single-doping), which facilitates the desorption of adsorbed water vapor. Furthermore, the enriched active oxygen species and catalytic sites on the dual-doped material surface enable H2S to compete with it the moment it enters the sensing surface, minimizing the impact of water. Overall, the dual modification of Pd and Ag on LaFeO3 achieves a strong combination of chemical sensitization and electronic sensitization, which not only enhances the sensitive response to H2S, but also builds a barrier against humidity interference.

[0043] The experimental materials used in the examples of the present invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0044] Example 1: Preparation of Ag / Pd-LaFeO3-based gas sensing material 2wt%Ag-2wt%Pd-LaFeO3

[0045] (1) 4.3301 g of La(NO3)3·6H2O, 4.0400 g of Fe(NO3)3·9H2O, 0.0766 g of AgNO3, and 0.0811 g of PdCl2 were mixed and dissolved in 110 mL of deionized water and mixed evenly to obtain a mixed solution. 10 g of citric acid and 10 mL of ethanol were added to the mixed solution and stirred for 2 h to obtain a sol.

[0046] (2) The sol was heated in a water bath at 80°C for 4 hours to age it to obtain a gel, and the gel was then dried at 80°C for 8 hours to obtain a dry gel, and the dry gel was placed in an air atmosphere and calcined at 800°C for 3 hours to obtain a gas sensing material based on Ag / Pd-LaFeO3, 2wt% Ag-2wt% Pd-LaFeO3.

[0047] The structure of the Ag / Pd-LaFeO3 gas sensing material prepared in this embodiment was characterized. Figure 1-Figure 3 As shown. Figure 1 It can be seen that the crystallization peaks correspond to the (101), (121) and (220) phases of LaFeO3 (No.37-1493), indicating that the material has a pure phase perovskite structure. Figure 2 It can be seen that the gas sensing material based on Ag / Pd-LaFeO3 presents a typical nanoparticle structure with a particle size of about 50-150nm, a large specific surface area and porosity, and provides abundant reaction sites and transmission channels for gas molecules. Figure 3 It can be seen that the elements are evenly distributed, proving that Ag and Pd are successfully loaded on the LaFeO3 surface.

[0048] Example 2: Preparation of Ag / Pd-LaFeO3-based gas sensing material 1wt%Ag-3wt%Pd-LaFeO3

[0049] (1) 4.3301 g of La(NO3)3·6H2O, 4.0400 g of Fe(NO3)3·9H2O, 0.0383 g of AgNO3, and 0.1212 g of PdCl2 were mixed and dissolved in 100 mL of deionized water and mixed evenly to obtain a mixed solution. 15 g of citric acid and 12 mL of ethanol were added to the mixed solution and stirred for 1.5 h to obtain a sol.

[0050] (2) The sol was heated in a water bath at 70°C for 6 hours to age it to obtain a gel, and the gel was then dried at 60°C for 12 hours to obtain a dry gel, and the dry gel was placed in an air atmosphere and calcined at 600°C for 4 hours to obtain a gas sensing material based on Ag / Pd-LaFeO3, 1wt% Ag-3wt% Pd-LaFeO3.

[0051] Example 3: Preparation of Ag / Pd-LaFeO3-based gas sensing material 3wt%Ag-1wt%Pd-LaFeO3

[0052] (1) 4.3301 g of La(NO3)3·6H2O, 4.0400 g of Fe(NO3)3·9H2O, 0.1148 g of AgNO3, and 0.0411 g of PdCl2 were mixed and dissolved in 100 mL of deionized water and mixed evenly to obtain a mixed solution. 8 g of citric acid and 8 mL of ethanol were added to the mixed solution and stirred for 1 h to obtain a sol.

[0053] (2) The sol was heated in a water bath at 90°C for 2 hours to age it to obtain a gel, and the gel was then dried at 80°C for 6 hours to obtain a dry gel, and the dry gel was placed in an air atmosphere and calcined at 900°C for 2 hours to obtain a gas sensing material based on Ag / Pd-LaFeO3, 3wt% Ag-1wt% Pd-LaFeO3.

[0054] Example 4: Preparation of H2S gas sensor

[0055] The 2wt% Ag-2wt% Pd-LaFeO3 prepared in Example 1, deionized water, and pineol were mixed in a ratio of 1 g:5 mL:1 mL to obtain a slurry; the slurry was spin-coated on the surface of an alumina ceramic substrate at a speed of 800 rpm to form a gas-sensitive film with a thickness of 100 μm. The gas-sensitive film was placed in air and aged at 180°C for 18 hours to obtain an H2S gas sensor.

[0056] Comparative Example 1: Preparation of LaFeO3 gas-sensitive material

[0057] The difference between this comparative example and Example 1 is that Ag and Pd are not used to dope LaFeO3. The details are as follows:

[0058] (1) Mix 4.3301 g of La(NO3)3·6H2O and 4.0400 g of Fe(NO3)3·9H2O, dissolve them in 110 mL of deionized water, and mix them evenly to obtain a mixed solution. Add 10 g of citric acid and 10 mL of ethanol to the mixed solution, stir for 2 h, and obtain a sol.

[0059] (2) The sol was heated in a water bath at 80°C for 4 hours to age it to obtain a gel, and the gel was then dried at 80°C for 8 hours to obtain a dry gel, and the dry gel was placed in an air atmosphere and calcined at 800°C for 3 hours to obtain a gas sensing material LaFeO3 based on Ag / Pd-LaFeO3.

[0060] Comparative Example 2: Preparation of 2wt% Ag-LaFeO3 gas-sensitive material

[0061] The difference between this comparative example and Example 1 is that only Ag is used to dope the LaFeO3 material. The details are as follows:

[0062] (1) 4.3301 g of La(NO3)3·6H2O, 4.0400 g of Fe(NO3)3·9H2O, and 0.0766 g of AgNO3 were mixed and dissolved in 110 mL of deionized water and mixed evenly to obtain a mixed solution. 10 g of citric acid and 10 mL of ethanol were added to the mixed solution and stirred for 2 h to obtain a sol.

[0063] (2) The sol was heated in a water bath at 80°C for 4 hours to age it to obtain a gel, and the gel was then dried at 80°C for 8 hours to obtain a dry gel, and the dry gel was placed in an air atmosphere and calcined at 800°C for 3 hours to obtain a gas sensing material based on Ag / Pd-LaFeO3 (2wt% Ag-LaFeO3 gas sensitive material).

[0064] Comparative Example 3: Preparation of 2wt% Pd-LaFeO3 gas-sensitive material

[0065] The difference between this comparative example and Example 1 is that only Pd is used to dope LaFeO3. The details are as follows:

[0066] (1) 4.3301 g of La(NO3)3·6H2O, 4.0400 g of Fe(NO3)3·9H2O, and 0.0811 g of PdCl2 were mixed and dissolved in 110 mL of deionized water and mixed evenly to obtain a mixed solution. 10 g of citric acid and 10 mL of ethanol were added to the mixed solution and stirred for 2 h to obtain a sol.

[0067] (2) The sol was heated in a water bath at 80°C for 4 hours to age it to obtain a gel, and the gel was then dried at 80°C for 8 hours to obtain a dry gel, and the dry gel was placed in an air atmosphere and calcined at 800°C for 3 hours to obtain a gas sensing material based on Ag / Pd-LaFeO3 with 2wt% Pd-LaFeO3 gas sensitive material.

[0068] Test Example 1:

[0069] The 2wt% Ag-2wt% Pd-LaFeO3 prepared in Example 1 and the gas-sensitive materials prepared in Comparative Examples 1-3 were coated on the gas-sensitive film, and their gas-sensitive responses (Rg / Ra) to H2S gas were tested. The results are as follows: Figure 4-Figure 6 As shown in Figure 2, Ra is the resistance of the sensor in air, and Rg is the resistance in the measured gas. The experimental environment is: relative humidity (RH) 20%, ambient temperature 20°C.

[0070] Depend on Figure 4It can be seen that the optimal operating temperature of the 2wt% Ag-2wt% Pd-LaFeO3 prepared in the present invention is 110°C. At 110°C, the response value of the 2wt% Ag-2wt% Pd-LaFeO3 prepared in Example 1 to 1 ppm H2S gas is 46.16; the response value of LaFeO3 prepared in Comparative Example 1 is 5.86; the response value of the 2wt% Ag-LaFeO3 prepared in Comparative Example 2 is 21.53; and the response value of the 2wt% Pd-LaFeO3 prepared in Comparative Example 3 is 23.76. These results demonstrate that dual noble metal modification with Ag and Pd has a significant synergistic effect in improving the H2S response value.

[0071] Figure 5 The gas sensing performance of 2wt% Ag-2wt% Pd-LaFeO3 prepared in Comparative Examples 1-3 and Example 1 to 1ppm H2S gas at different humidity. Figure 5 It can be seen that the gas sensing performance decreases slightly with increasing relative humidity. However, the response value change rate of the 2wt% Ag-2wt% Pd-LaFeO3 prepared by the present invention is less than 5% when the relative humidity is less than 70%, indicating that the material has good humidity resistance.

[0072] Figure 6 The long-term stability of 2wt% Ag-2wt% Pd-LaFeO3 prepared in Example 1 to 1ppm H2S gas is shown. Figure 6 It can be seen that within one month, the response value change rate is <6%, indicating that the material has extremely high gas-sensing stability.

[0073] 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. A gas sensing material based on Ag / Pd-LaFeO3, characterized in that: The chemical formula of the gas sensing material is X wt% Ag-Y wt% Pd-LaFeO3; Wherein, Xwt% is the doping amount of Ag in the gas sensing material, and Ywt% is the doping amount of Pd in the gas sensing material; <X≤5,0<Y≤5。 2. The method for preparing the Ag / Pd-LaFeO3-based gas sensing material according to claim 1, characterized in that: The following steps are involved: (1) La(NO3)3·6H2O, Fe(NO3)3·9H2O, AgNO3, and PdCl2 were mixed and dissolved in deionized water, and the mixture was mixed to obtain a mixed solution; citric acid and ethanol were added to the mixed solution and stirred to obtain a sol; (2) heating the sol to age it to obtain a gel; drying the gel to obtain a xerogel; and calcining the xerogel to obtain a gas sensing material based on Ag / Pd-LaFeO3; The addition ratios of La(NO3)3·6H2O, Fe(NO3)3·9H2O, AgNO3, PdCl2, citric acid, ethanol, and deionized water were (0.01–0.05) mol: (0.01–0.05) mol: (0.01–0.5) g: (0.01–0.5) g: (5–20) g: (5–15) mL: (50–150) mL.

3. The method for preparing a gas sensing material based on Ag / Pd-LaFeO3 according to claim 2, wherein: In step (1), the stirring time is 1-2h.

4. The method for preparing a gas sensing material based on Ag / Pd-LaFeO3 according to claim 2, wherein: In step (2), the heating temperature is 70-90° C. and the heating time is 2-6 h.

5. The method for preparing a gas sensing material based on Ag / Pd-LaFeO3 according to claim 2, wherein: In step (2), the drying temperature is 60-80° C. and the drying time is 6-12 h.

6. The method for preparing a gas sensing material based on Ag / Pd-LaFeO3 according to claim 2, wherein: In step (2), the calcination atmosphere is air atmosphere, the calcination temperature is 600-900°C, and the calcination time is 2-4 hours.

7. Use of the Ag / Pd-LaFeO3-based gas sensing material according to claim 1 in the following (1) or (2): (1) H2S gas in municipal sewage environment; (2) Preparation of H2S gas sensor.

8. The use according to claim 7, characterized in that The concentration of H2S gas is 0.5-5ppm.

9. The use according to claim 7, characterized in that The operating temperature of the H2S gas sensor is 60-200℃.

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