Gas-sensitive material based on double noble metal doped holmium iron oxide and application of gas-sensitive material in detection of hydrogen sulfide in sulfur-containing ore body exploration environment

Abstract

The invention discloses a gas-sensitive material based on double noble metal doped holmium iron oxide and application of the gas-sensitive material to detection of hydrogen sulfide in a sulfur-containing ore body exploration environment, and relates to the technical field of gas-sensitive materials. HoFeO3 is used as a substrate material, and two elements of Au and Pt are used for doping modification of the HoFeO3 to prepare the gas sensitive material based on double noble metal doped holmium iron oxide. Au and Pt are combined to perform doping modification on HoFeO3, a synergistic effect is achieved on improving the temperature stability of the gas-sensitive material, the sensitivity of the gas-sensitive material in a high-humidity environment can be improved, in addition, due to the synergistic catalysis effect of Au and Pt, an energy barrier of H2S adsorption reaction can be remarkably reduced, surface electron transfer and reaction activity are promoted, and the sensitivity of the gas-sensitive material in a high-humidity environment is improved. Therefore, the working temperature is reduced, the response value is improved, and the method is suitable for detecting hydrogen sulfide gas in a sulfur ore body exploration environment.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-sensitive materials, and in particular to a gas-sensitive material based on double noble metal doped holmium iron oxide and its application in detecting hydrogen sulfide in a sulfur-containing ore body exploration environment. Background Art

[0002] Hydrogen sulfide (H2S) is a common toxic and hazardous gas in coal mines. my country's Coal Mine Safety Regulations stipulate that H2S concentrations in underground coal mines should not exceed 6.6 ppm. Excessive H2S concentrations underground not only pose an explosion hazard but can also cause poisoning and death to workers. Furthermore, H2S is chemically reactive and can corrode underground metal equipment, causing damage such as hydrogen embrittlement and fracture, posing a serious safety hazard. Furthermore, H2S has a strong pungent odor and is suffocating. Different concentrations of H2S can cause varying degrees of damage to the human body, and in severe cases, can lead to central nervous system disorders and even suffocation.

[0003] Gas sensors are a common method for detecting H2S gas. Upon contact with H2S gas, they are expected to react rapidly, causing a change in the measured parameter (such as resistance), thereby converting the H2S gas concentration into an electrochemical signal, enabling quantitative detection of H2S gas. The core of a gas sensor is the gas-sensitive material. Currently, commonly used gas-sensitive materials include perovskite materials and metal oxides. Among them, the perovskite p-type oxide HoFeO3, with its stable lattice structure, abundant oxygen vacancies, and adjustable valence state, has been widely studied as a substrate material for gas detection.

[0004] The temperature and humidity of the detection environment significantly affect the gas sensitivity of gas-sensitive materials. With the increasing demand for coal resources, the mining depth of coal mines is also increasing year by year. As the mining depth of the mine increases, the temperature of the exploration environment also rises, generally at a rate of 2-3°C / 100m. The mining depth of coal mines in my country is mostly concentrated between 600-1500m. Therefore, the temperature range in the exploration environment of sulfur-containing ore bodies is large, which requires gas-sensitive materials to have a small sensitivity change within a wide temperature range. Furthermore, since the humidity in ore exploration environments is generally high, generally between 50% and 80%, gas-sensitive materials used to detect H2S gas in sulfur-containing ore exploration environments must have both good response stability over a wide temperature range and sensitive response at high humidity.

[0005] CN119143186B discloses an Au- and Co-doped holmium ferrite gas-sensitive material, prepared via a sol-gel method from holmium nitrate, ferric nitrate, cobalt nitrate, and chloroauric acid. However, this gas-sensitive material can be used to detect formaldehyde gas, and its response variation is only guaranteed to be less than 10% within the temperature range of 120°C to 150°C. Its response is very low in high humidity, making it unsuitable for detecting hydrogen sulfide gas in sulfur-bearing ore exploration environments.

[0006] Therefore, there is an urgent need to use HoFeO3 as a base material and perform doping and modification treatment on it to produce a hydrogen sulfide gas-sensitive material, so that the gas-sensitive material has good response stability in a wide temperature range and excellent sensitivity under high humidity conditions, so as to be suitable for the detection of hydrogen sulfide gas in the sulfur-containing ore exploration environment. Summary of the Invention

[0007] In view of the above-mentioned prior art, the purpose of the present invention is to provide a gas-sensitive material based on double-noble metal doped holmium iron oxide and its application in detecting hydrogen sulfide in the exploration environment of sulfur-containing ore bodies. The present invention uses HoFeO3 as a base material and adopts Au and Pt as two elements to dope and modify it to obtain a gas-sensitive material based on double-noble metal doped holmium iron oxide. The combination of Au and Pt to dope and modify HoFeO3 has a synergistic effect in improving the temperature stability of the gas-sensitive material and can also improve the sensitivity of the gas-sensitive material in a high-humidity environment. In addition, the present invention adopts the synergistic catalytic effect of Au and Pt, which can significantly reduce the energy barrier of the H2S adsorption reaction, promote surface electron transfer and reaction activity, thereby reducing the operating temperature and improving the response value, which is suitable for the detection of hydrogen sulfide gas in the exploration environment of sulfur ore bodies.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The first aspect of the present invention provides a method for preparing a gas-sensitive material based on a double noble metal doped holmium iron oxide, comprising the following steps:

[0010] (1) Ho(NO3)3·6H2O, Fe(NO3)3·9H2O and citric acid are mixed and added to water, and then NaOH solution is added to react. After the reaction is completed, the mixture is filtered, washed and dried to obtain a HoFeO3 precursor;

[0011] (2) dispersing a HoFeO3 precursor in water to obtain a HoFeO3 solution; adding HAuCl4·4H2O and PtCl4 to the HoFeO3 solution and reacting the mixture; collecting the solid after the reaction, washing, drying, and calcining the solid to obtain a gas-sensitive material based on a double noble metal doped holmium iron oxide;

[0012] Among them, the addition ratios of Ho(NO3)3·6H2O, Fe(NO3)3·9H2O, HAuCl4·4H2O, PtCl4, and citric acid are (0.01-0.05) mol: (0.01-0.05) mol: (0.01-0.5) g: (0.01-0.5) g: (5-20) g.

[0013] Preferably, in step (1), the concentration of the NaOH solution is 1-2 mol / L.

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

[0015] Preferably, in step (1), the washing process is: washing the filtered solid with deionized water and ethanol 3-5 times each.

[0016] Preferably, in step (1), the drying method is vacuum drying, the drying temperature is 70-90° C., and the drying time is 6-12 h.

[0017] Preferably, in step (2), the reaction temperature is 60-80° C. and the reaction time is 2-4 h.

[0018] Preferably, in step (2), the drying method is vacuum drying, the drying temperature is 70-90° C., and the drying time is 6-12 h.

[0019] Preferably, in step (2), during the calcination process, the calcination atmosphere is an air atmosphere, the calcination temperature is 400-600° C., and the calcination time is 2.5-3.5 h.

[0020] The second aspect of the present invention provides a gas-sensitive material based on double noble metal doped holmium iron oxide prepared by the above preparation method, the chemical formula of which is X wt% Au-Y wt% Pt-HoFeO3;

[0021] Wherein, Xwt% is the doping amount of Au in the double noble metal doped holmium iron oxide gas sensing material, and Ywt% is the doping amount of Pt in the double noble metal doped holmium iron oxide gas sensing material; <X≤5,0<Y≤5。

[0022] The third aspect of the present invention provides the application of the above-mentioned double noble metal doped holmium iron oxide gas-sensitive material in the following (1)-(2):

[0023] (1) Detection of hydrogen sulfide gas in the exploration environment of sulfur-containing ore bodies;

[0024] (2) Preparation of hydrogen sulfide gas sensor.

[0025] Preferably, the concentration of hydrogen sulfide gas is 0.5-5 ppm.

[0026] Preferably, the hydrogen sulfide gas sensor is prepared by the following method:

[0027] The above-mentioned double noble metal-doped holmium iron oxide gas-sensitive material, deionized water, and terpineol are mixed in the ratio of (1-3) g: (5-10) mL: (1-3) mL to prepare a slurry; the slurry is spin-coated on an alumina ceramic substrate to form a gas-sensitive film with a thickness of 50-200 μm, and the gas-sensitive film is aged at 180-200° C. for 12-24 hours to obtain a hydrogen sulfide gas sensor.

[0028] Preferably, the operating temperature of the hydrogen sulfide gas sensor is 60-200°C.

[0029] Beneficial effects of the present invention:

[0030] 1. The present invention uses HoFeO3 as a base material and adopts Au and Pt as the two elements to dope and modify it to obtain a gas-sensitive material based on a double noble metal doped holmium iron oxide. The combination of Au and Pt in doping and modifying HoFeO3 has a synergistic effect in improving the temperature stability of the gas-sensitive material. In addition, the doping and modification of HoFeO3 by the combination of Au and Pt in the present invention can also improve the sensitivity of the gas-sensitive material under high humidity. Specifically, the response change rate of the gas-sensitive material based on a double noble metal doped holmium iron oxide prepared by the present invention is less than 10% in the temperature range of 90-130°C; when the relative humidity is less than 70%, the response value change rate is less than 5%. In addition, the gas-sensitive material remains stable under humidity changes (relative humidity <50%) and shows excellent stability in long-term use (response value change <5% within one month), making it suitable for environmental monitoring and industrial emission detection.

[0031] 2. The present invention can significantly reduce the energy barrier of the H2S adsorption reaction through the synergistic catalytic effect of Au and Pt, promote surface electron transfer and reaction activity, thereby reducing the operating temperature and improving the response value. At the same time, the modification of Au and Pt enhances the selective adsorption capacity of the material for H2S molecules, suppresses the response to other interfering gases, and exhibits excellent selectivity. Specifically, the response value of the dual noble metal Au and Pt modified HoFeO3 prepared by the present invention to 1ppm H2S gas at an operating temperature of 100°C is 59.38. The H2S gas sensor prepared by the present invention has a low operating temperature, low energy consumption, is easy to be integrated into portable devices, and has broad application prospects.

[0032] 3. The double-noble-metal-doped holmium iron oxide gas-sensitive material prepared by the co-precipitation method in the present invention has a nanoparticle structure with a particle size of 50-150 nm and a large specific surface area, which can provide more adsorption and reaction sites for H2S molecules, further improving the sensitivity and response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 : XRD pattern of the double noble metal-doped holmium iron oxide gas-sensitive material prepared in Example 1;

[0034] Figure 2 : SEM image of the double noble metal-doped holmium iron oxide gas-sensitive material prepared in Example 1;

[0035] Figure 3 : EDS Mapping of Au, Pt and Ho elements in the double noble metal doped holmium iron oxide gas-sensitive material prepared in Example 1;

[0036] 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;

[0037] Figure 5 : Relationship diagrams of the gas-sensing performance of the gas-sensitive materials prepared in Example 1 and Comparative Examples 1-3 to 1 ppm H2S gas and humidity; wherein, (a) is a relationship diagram of the gas-sensing performance of the gas-sensitive material prepared in Example 1 to 1 ppm H2S gas and humidity; (b) is a relationship diagram of the gas-sensing performance of the gas-sensitive material prepared in Comparative Example 3 to 1 ppm H2S gas and humidity; (c) is a relationship diagram of the gas-sensing performance of the gas-sensitive material prepared in Comparative Example 2 to 1 ppm H2S gas and humidity; (d) is a relationship diagram of the gas-sensing performance of the gas-sensitive material prepared in Comparative Example 1 to 1 ppm H2S gas and humidity;

[0038] Figure 6 : Schematic diagram of the long-term gas-sensitive stability of the double noble metal-doped holmium iron oxide gas-sensitive material prepared in Example 1 to 1 ppm H2S gas. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] In the existing technology, since the temperature of the sulfur-containing ore body exploration environment increases with the increase of mine depth, and the humidity in the ore body exploration environment is usually high, this requires that the gas-sensitive materials used to detect hydrogen sulfide gas in the sulfur-containing ore body exploration environment have response stability within a wide temperature range and sensitivity under high ambient humidity.

[0042] Based on this, the applicant discovered that the use of dual noble metal synergistic modification can leverage the complementary advantages of different noble metals in electronic structure and catalytic properties. By modifying the surface of HoFeO3 with noble metal nanoparticles, the present invention can utilize the Schottky barrier formed by the noble metal-semiconductor to regulate carrier distribution, and enhance the activation ability of oxygen molecules through the surface chemical sensitization effect of the noble metal, thereby reducing the operating temperature and improving the gas response. Specifically:

[0043] The present invention uses Au and Pt to dope and modify HoFeO3, which can effectively improve the temperature stability of gas-sensitive materials. The principle is mainly reflected in the following four points: (1) Catalytic stabilization of metal nanoparticles: Au and Pt noble metal nanoparticles have excellent catalytic activity, forming uniformly distributed catalytic active centers on the surface of HoFeO3, effectively promoting the oxygen adsorption, dissociation and migration processes in gas-sensitive reactions. This catalytic effect reduces the energy barrier required for the reaction, allowing the material to maintain stable gas response characteristics within a wide temperature range, thereby enhancing the temperature stability of the material. (2) Schottky junction stabilization of the noble metal-HoFeO3 interface: Au and Pt doping forms a metal-semiconductor interface on the surface of HoFeO3, namely a Schottky junction structure. This interface structure can effectively regulate the Fermi level and carrier concentration of the material, improve the stability of the carrier concentration, keep the conductive mechanism of the material stable under temperature fluctuation conditions, avoid electron migration disorder caused by temperature changes, and thus significantly improve the temperature stability of the material. (3) Precious metal doping reduces surface activation energy: Au and Pt doping effectively reduces the activation energy of gas molecule adsorption and desorption reactions by enhancing the content and stability of oxygen vacancies on the material surface. This activation energy reduction effect reduces the sensitivity of the material's sensitive reaction process to temperature, thereby reducing the negative impact of temperature fluctuations on material properties and significantly improving the long-term stability of the material. (4) Nanoparticles inhibit grain growth and sintering: Au and Pt particles are distributed in the HoFeO3 matrix, acting as a physical barrier to grain growth, effectively inhibiting the grain growth and sintering of the material under long-term high-temperature working conditions, and maintaining a high specific surface area and active reaction site density. This effect greatly enhances the structural stability of the material, thereby improving the overall temperature stability of the material.

[0044] In addition, the present invention uses a co-precipitation method to prepare a Pt and Au co-doped HoFeO3 gas-sensitive material. This gas-sensitive material has excellent selectivity and sensitivity to hydrogen sulfide gas. Au has a high work function and can form an electron depletion layer on the surface, increasing the adsorbed oxygen concentration; Pt has a low activation energy for S–H bond cleavage and can quickly catalyze the oxidation of H2S to SO2, thereby enhancing molecular recognition capabilities. Co-loading Au and Pt on the HoFeO3 surface is expected to achieve highly sensitive and selective detection of H2S at relatively low temperatures (≤150°C) and significantly suppress responses to interfering gases such as SO2 and CH4, thereby resolving the aforementioned technical bottlenecks and meeting the actual needs of mine safety monitoring.

[0045] 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.

[0046] Example 1: Preparation of 2wt% Au-2wt% Pt-HoFeO3 gas-sensitive material based on double noble metal doped holmium iron oxide

[0047] (1) 4.590 g of Ho(NO3)3·6H2O, 4.040 g of Fe(NO3)3·9H2O, and 10 g of citric acid were mixed and added to 100 mL of deionized water. 60 mL of 1 mol / L NaOH solution was then added and reacted for 1.5 h. After the reaction was completed, the mixture was filtered and the filtered precipitate was collected. The mixture was washed with deionized water and ethanol three times each, and then dried in vacuum at 80 °C for 8 h to obtain a HoFeO3 precursor.

[0048] (2) The HoFeO3 precursor prepared in step (1) was dispersed in 50 mL of deionized water to obtain a HoFeO3 solution; 0.122 g of HAuCl4·4H2O and 0.101 g of PtCl4 were added to the HoFeO3 solution, and an in-situ deposition reaction was carried out at 70°C for 3 h. The solid after the reaction was collected, washed, vacuum-dried at 80°C for 8 h, and then calcined at 500°C for 3 h to obtain a 2 wt% Au-2 wt% Pt-HoFeO3 gas-sensitive material based on a double noble metal doped holmium iron oxide.

[0049] Example 2: Preparation of 1wt% Au-3wt% Pt-HoFeO3 gas-sensitive material based on double noble metal doped holmium iron oxide

[0050] (1) 4.590 g of Ho(NO3)3·6H2O, 4.040 g of Fe(NO3)3·9H2O, and 15 g of citric acid were mixed and added to 100 mL of deionized water. 55 mL of 1 mol / L NaOH solution was then added and reacted for 2 h. After the reaction was completed, the mixture was filtered and the filtered precipitate was collected. The mixture was washed with deionized water and ethanol four times each, and then dried in vacuum at 70 °C for 12 h to obtain a HoFeO3 precursor.

[0051] (2) The HoFeO3 precursor prepared in step (1) was dispersed in 50 mL of deionized water to obtain a HoFeO3 solution; 0.059 g of HAuCl4·4H2O and 0.145 g of PtCl4 were added to the HoFeO3 solution, and an in-situ deposition reaction was carried out at 80°C for 2 h. The solid after the reaction was collected, washed, vacuum-dried at 70°C for 12 h, and then calcined at 600°C for 2.5 h to obtain a 1 wt% Au-3 wt% Pt-HoFeO3 gas-sensitive material based on a double noble metal doped holmium iron oxide.

[0052] Example 3: Preparation of 3wt% Au-1wt% Pt-HoFeO3 gas-sensitive material based on double noble metal doped holmium iron oxide

[0053] (1) 4.590 g of Ho(NO3)3·6H2O, 4.040 g of Fe(NO3)3·9H2O, and 8 g of citric acid were mixed and added to 100 mL of deionized water. 70 mL of 1 mol / L NaOH solution was then added and reacted for 1 h. After the reaction was completed, the mixture was filtered and the filtered precipitate was collected. The mixture was washed with deionized water and ethanol five times each, and then dried in vacuum at 90 °C for 6 h to obtain a HoFeO3 precursor.

[0054] (2) The HoFeO3 precursor prepared in step (1) was dispersed in 50 mL of deionized water to obtain a HoFeO3 solution; 0.173 g of HAuCl4·4H2O and 0.048 g of PtCl4 were added to the HoFeO3 solution, and an in-situ deposition reaction was carried out at 60°C for 4 h. The solid after the reaction was collected, washed, and vacuum-dried at 90°C for 6 h, and then calcined at 400°C for 3.5 h to obtain a 3wt% Au-1wt% Pt-HoFeO3 gas-sensitive material based on double noble metal doped holmium iron oxide.

[0055] Example 4: Preparation of H2S gas sensor

[0056] The double noble metal-doped holmium iron oxide gas-sensitive material 2wt% Au-2wt% Pt-HoFeO3 prepared in Example 1, deionized water and pine alcohol 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.

[0057] Comparative Example 1: Preparation of HoFeO3 gas-sensitive material

[0058] The difference between this comparative example and Example 1 is that the holmium ferrite material is not doped with noble metals. The specific preparation method is:

[0059] Mix 4.590g Ho(NO3)3·6H2O, 4.040g Fe(NO3)3·9H2O and 10g citric acid, add to 100mL deionized water, then add 60mL of 1mol / L NaOH solution and react for 1.5h. After the reaction is completed, filter and collect the filtered precipitate, wash it with deionized water and ethanol three times respectively, and then dry it in vacuum at 80℃ for 8h to obtain HoFeO3 gas-sensitive material without doping with precious metals.

[0060] Comparative Example 2: Preparation of 2wt% Au-HoFeO3 gas-sensitive material

[0061] The difference between this comparative example and Example 1 is that only Au is used to dope the holmium ferrite material. The specific preparation method is as follows:

[0062] (1) 4.590 g of Ho(NO3)3·6H2O, 4.040 g of Fe(NO3)3·9H2O, and 10 g of citric acid were mixed and added to 100 mL of deionized water. 60 mL of 1 mol / L NaOH solution was then added and reacted for 1.5 h. After the reaction was completed, the mixture was filtered and the filtered precipitate was collected. The mixture was washed with deionized water and ethanol three times each, and then dried in vacuum at 80 °C for 8 h to obtain a HoFeO3 precursor.

[0063] (2) The HoFeO3 precursor prepared in step (1) was dispersed in 50 mL of deionized water to obtain a HoFeO3 solution; 0.122 g of HAuCl4·4H2O was added to the HoFeO3 solution, and an in-situ deposition reaction was carried out at 70°C for 3 h. The solid after the reaction was collected, washed, vacuum-dried at 80°C for 8 h, and then calcined at 500°C for 3 h to obtain a 2 wt% Au-HoFeO3 gas-sensitive material based on precious metal doped holmium iron oxide.

[0064] Comparative Example 3: Preparation of 2wt% Pt-HoFeO3 gas-sensitive material

[0065] The difference between this comparative example and Example 1 is that only Pt is used to dope the holmium ferrite material. The specific preparation method is as follows:

[0066] (1) 4.590 g of Ho(NO3)3·6H2O, 4.040 g of Fe(NO3)3·9H2O, and 10 g of citric acid were mixed and added to 100 mL of deionized water. 60 mL of 1 mol / L NaOH solution was then added and reacted for 1.5 h. After the reaction was completed, the mixture was filtered and the filtered precipitate was collected. The mixture was washed with deionized water and ethanol three times each, and then dried in vacuum at 80 °C for 8 h to obtain a HoFeO3 precursor.

[0067] (2) The HoFeO3 precursor prepared in step (1) was dispersed in 50 mL of deionized water to obtain a HoFeO3 solution; 0.101 g of PtCl4 was added to the HoFeO3 solution, and an in-situ deposition reaction was carried out at 70°C for 3 hours. The solid after the reaction was collected, washed, and vacuum-dried at 80°C for 8 hours, and then calcined at 500°C for 3 hours to obtain a 2 wt% Pt-HoFeO3 gas-sensitive material based on precious metal doped holmium iron oxide.

[0068] Test Example 1:

[0069] The structure of the double noble metal doped holmium iron oxide gas sensitive material prepared in Example 1 was characterized. Figure 1-Figure 3 shown.

[0070] Figure 1 The XRD pattern of HoFeO3 modified with double noble metals Au and Pt is shown in Figure 2. Figure 1 It can be seen that the crystallization peaks correspond to the (111), (112) and (312) phases of HoFeO3 (No.46-0115), indicating that the material has a pure phase perovskite structure. Figure 2 It can be seen that the prepared dual noble metal Au and Pt modified HoFeO3 presents a typical nanoparticle structure with a particle size of about 50-150nm, a large specific surface area and porosity, providing abundant reaction sites and transmission channels for gas molecules. Figure 3 is the EDS Mapping diagram of Au, Pt, and Ho elements, Figure 3 It can be seen that the elements are evenly distributed, proving that Au and Pt are successfully loaded on the HoFeO3 surface.

[0071] Test Example 2:

[0072] The 2wt% Au-2wt% Pt-HoFeO3 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 6As 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.

[0073] Depend on Figure 4 It can be seen that the response change rate of the 2wt% Au-2wt% Pt-HoFeO3 prepared by the present invention is less than 10% in the temperature range of 90-130°C, and the temperature response change rate in this range is specifically 9.37%. The response change rate of the HoFeO3 prepared in Comparative Example 1 is 69.05% in the temperature range of 90-130°C, the response change rate of the 2wt% Au-HoFeO3 prepared in Comparative Example 2 is 64.61% in the temperature range of 90-130°C, and the response change rate of the 2wt% Pt-HoFeO3 prepared in Comparative Example 3 is 52.71% in the temperature range of 90-130°C. This shows that the present invention uses Au and Pt, two precious metals, to dope and modify the HoFeO3 material, which has a synergistic effect in improving the temperature stability of the gas-sensitive material.

[0074] The calculation formula of the response change rate is as follows:

[0075] Response change rate (%) = [(R max -R min ) / R max ]×100%;

[0076] Where R max and R min They respectively represent the maximum response value and minimum response value of the gas-sensitive material within a certain temperature range.

[0077] In addition, by Figure 4 It can also be seen that the optimal operating temperature of the 2wt% Au-2wt% Pt-HoFeO3 prepared in the present invention is 100°C. At 100°C, the response value of the 2wt% Au-2wt% Pt-HoFeO3 prepared in Example 1 to 1 ppm H2S gas is 59.38; the response value of the HoFeO3 prepared in Comparative Example 1 is 6.98; the response value of the 2wt% Au-HoFeO3 prepared in Comparative Example 2 is 23.65; and the response value of the 2wt% Pt-HoFeO3 prepared in Comparative Example 3 is 27.83. These results demonstrate that dual noble metal modification of Au and Pt has a significant synergistic effect in improving the H2S response value.

[0078] Figure 5 The gas sensing performance of the gas-sensitive materials of Comparative Examples 1-3 and Example 1 to 1ppm H2S gas at different humidity. Figure 5It can be seen that the gas-sensing performance decreases slightly with the increase of relative humidity, but when the relative humidity is <70%, the response value change rate is <5%, indicating that the material has good humidity resistance.

[0079] Figure 6 The long-term stability of 2wt% Au-2wt% Pt-HoFeO3 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 <5%, indicating that the material has extremely high gas-sensing stability.

[0080] 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 preparation method of a gas-sensitive material based on double noble metal doped holmium iron oxide, characterized in that: The following steps are involved: (1) Ho(NO3)3·6H2O, Fe(NO3)3·9H2O and citric acid are mixed and added to water, and then NaOH solution is added to react. After the reaction is completed, the mixture is filtered, washed and dried to obtain a HoFeO3 precursor; (2) dispersing a HoFeO3 precursor in water to obtain a HoFeO3 solution; adding HAuCl4·4H2O and PtCl4 to the HoFeO3 solution and reacting the mixture; collecting the solid after the reaction, washing, drying, and calcining the solid to obtain a gas-sensitive material based on a double noble metal doped holmium iron oxide; Among them, the addition ratio of Ho(NO3)3·6H2O, Fe(NO3)3·9H2O, HAuCl4·4H2O, PtCl4 and citric acid is (0.01-0.05)mol: (0.01-0.05)mol: (0.01-0.5)g: (0.01-0.5)g: (5-20)g.

2. The method for preparing a gas-sensitive material based on double noble metal doped holmium iron oxide according to claim 1, characterized in that: In step (1), the concentration of the NaOH solution is 1-2 mol / L, and the reaction time is 1-2 h.

3. The method for preparing a gas-sensitive material based on double noble metal doped holmium iron oxide according to claim 1, characterized in that: In step (1), the drying method is vacuum drying, the drying temperature is 70-90° C., and the drying time is 6-12 h.

4. The method for preparing a gas-sensitive material based on double noble metal doped holmium iron oxide according to claim 1, characterized in that: In step (2), the reaction temperature is 60-80° C. and the reaction time is 2-4 h.

5. The method for preparing a gas-sensitive material based on double noble metal doped holmium iron oxide according to claim 1, characterized in that: In step (2), the calcination atmosphere is air atmosphere, the calcination temperature is 400-600° C., and the calcination time is 2.5-3.5 hours.

6. The gas-sensitive material based on double noble metal doped holmium iron oxide prepared by the preparation method according to any one of claims 1 to 5, characterized in that: Its chemical formula is X wt% Au-Y wt% Pt-HoFeO3; Wherein, Xwt% is the doping amount of Au in the double noble metal doped holmium iron oxide gas sensing material, and Ywt% is the doping amount of Pt in the double noble metal doped holmium iron oxide gas sensing material; <X≤5,0<Y≤5。 7. Application of the double noble metal doped holmium iron oxide gas-sensitive material according to claim 6 in the following (1)-(2): (1) Detection of hydrogen sulfide gas in the exploration environment of sulfur-containing ore bodies; (2) Preparation of hydrogen sulfide gas sensor.

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

9. The use according to claim 7, characterized in that The hydrogen sulfide gas sensor is prepared by the following method: The double noble metal-doped holmium iron oxide gas-sensitive material according to claim 6, deionized water, and terpineol are mixed in the ratio of (1-3) g: (5-10) mL: (1-3) mL to prepare a slurry; the slurry is spin-coated on an alumina ceramic substrate to form a gas-sensitive film with a thickness of 50-200 μm, and the gas-sensitive film is aged at 180-200° C. for 12-24 h to obtain a hydrogen sulfide gas sensor.

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

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