Composite material based on PdAu alloy and In2O3 as well as preparation method and application of composite material

Abstract

The invention relates to the field of gas sensors, and discloses a composite material based on a PdAu alloy and In2O3 as well as a preparation method and application of the composite material. The composite material based on the PdAu alloy and the In2O3 is prepared from the In2O3 and PdAu alloy nano particles loaded on the In2O3. The composite material based on the PdAu alloy and the In2O3 has a relatively large specific surface area and excellent catalytic activity, can work under a room temperature condition when being applied to a sensor, and is high in response speed to hydrogen, wide in detectable hydrogen volume concentration range, low in detection lower limit, simple in preparation process operation and easy to industrialize.

Description

Technical Field

[0001] This invention relates to the field of gas sensors, specifically to a composite material based on PdAu alloy and In2O3, its preparation method, and its application. Background Technology

[0002] Hydrogen, as an abundant and renewable clean energy source, can replace traditional fossil fuels in future energy systems, reducing environmental pollution and greenhouse gas emissions, and ensuring energy supply security. However, H2's high diffusion coefficient, low ignition energy, rapid flame propagation speed, and wide explosion range result in significant safety risks from H2 leaks. Therefore, effective detection of hydrogen is crucial for early warning, monitoring, control, and disaster mitigation during the production, storage, transportation, and use stages.

[0003] Currently, widely researched H2 sensors are based on metal-oxide-semiconductor (MOS). MOS-based hydrogen sensors have advantages such as high sensitivity, short response time, and low detection limit, but their widespread application is limited by high operating temperature, high power consumption, and poor mechanical properties. In2O3, due to its excellent stability and surface activity, has become a sensing material for detecting various toxic and harmful gases; however, pure In2O3 sensors have poor sensitivity and selectivity, and high energy consumption. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of low sensitivity and poor selectivity of existing In2O3 hydrogen sensing materials, and to provide a composite material based on PdAu alloy and In2O3 (PdAu@In2O3). This composite material based on PdAu alloy and In2O3 has a large specific surface area and excellent catalytic activity. When applied in sensors, it can operate at room temperature and has a fast response to H2. It can detect a wide range of H2 volume concentrations with a low detection limit. The preparation process is simple and easy to industrialize.

[0005] To achieve the above objectives, the present invention provides a composite material based on PdAu alloy and In2O3, wherein the composite material includes In2O3 and PdAu alloy nanoparticles supported on In2O3.

[0006] Preferably, the weight ratio of PdAu alloy nanoparticles to In2O3 is 5–30:100.

[0007] Preferably, the particle size of the PdAu alloy nanoparticles is 5-15 nm.

[0008] Preferably, the molar ratio of Pd to Au in the PdAu alloy nanoparticles is 1 to 3:1.

[0009] A second aspect of the present invention provides a method for preparing a composite material based on PdAu alloy and In2O3, the method comprising the following steps:

[0010] (1) The precursor solution, In2O3 and reducing agent are mixed and the first reaction is carried out;

[0011] (2) The material obtained in step (1) is subjected to solid-liquid separation, and then the obtained solid intermediate material A is dried and calcined for the first time;

[0012] In step (1), the precursor solution contains Pd precursor and Au precursor.

[0013] Preferably, in step (1), the ratio of the total weight of the Pd precursor and the Au precursor to the weight of In2O3 is 1 to 5:10, wherein both the Pd precursor and the Au precursor are calculated as metals.

[0014] Preferably, in step (1), the molar ratio of Pd precursor to Au precursor is 1 to 3:1, wherein both Pd precursor and Au precursor are calculated as metals.

[0015] Preferably, in step (1), the total weight ratio of the Pd precursor and the Au precursor to the reducing agent is 1:5 to 50, wherein both the Pd precursor and the Au precursor are calculated as metals.

[0016] Preferably, in step (1), the conditions for the first reaction include: a temperature of 80 to 150°C and a time of 5 to 20 hours.

[0017] Preferably, in step (1), the preparation method of In2O3 includes: mixing an In precursor solution, methanol and polyvinylpyrrolidone and carrying out a second reaction, then performing solid-liquid separation, and drying and second calcining the obtained solid intermediate material B.

[0018] Preferably, the conditions for the second reaction include: a temperature of 120–200°C and a time of 3–15 h.

[0019] Preferably, the conditions for the second calcination include: a temperature of 450–600°C and a time of 3–24 hours.

[0020] Preferably, the weight ratio of In precursor, methanol, and polyvinylpyrrolidone in the In precursor solution is 1:8-20:40-80, wherein the In precursor is calculated as In element.

[0021] Preferably, in step (1), the reducing agent is selected from one or more of sodium borohydride, ascorbic acid and hydrazine hydrate.

[0022] Preferably, in step (2), the conditions for the first calcination include: a temperature of 400-600°C and a time of 5-20 hours.

[0023] A third aspect of the present invention provides a composite material based on PdAu alloy and In2O3 prepared by the above method.

[0024] The fourth aspect of this invention provides the application of the above-mentioned composite material based on PdAu alloy and In2O3 in hydrogen detection.

[0025] A fifth aspect of the present invention provides a hydrogen sensor comprising the aforementioned composite material based on PdAu alloy and In2O3.

[0026] The sixth aspect of the present invention provides a method for preparing the above-mentioned hydrogen sensor, the method comprising: mixing and grinding the above-mentioned composite material based on PdAu alloy and In2O3 with an organic solvent, then coating it onto the surface of a ceramic tube with electrodes and performing heat treatment.

[0027] Preferably, the heat treatment conditions include: a temperature of 60–100°C and a time of 2–10 hours.

[0028] A seventh aspect of the present invention provides a method for detecting hydrogen, the method comprising contacting the above-mentioned composite material based on PdAu alloy and In2O3 with a mixed gas containing hydrogen.

[0029] Preferably, the volume content of hydrogen in the mixed gas is 0.01-50%.

[0030] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0031] (1) When the composite material based on PdAu alloy and In2O3 described in this invention is used in a sensor, it can work at room temperature and has a fast response speed to H2. It can detect a wide range of H2 volume concentrations and has a low detection limit. It can respond to H2 with a volume concentration of 0.01% within 10s and can detect volume concentrations from 0.01% to 50%. This is mainly because PdAu alloy nanoparticles have a large specific surface area, which can quickly adsorb and dissociate H2 as active sites.

[0032] (2) The method for preparing composite materials based on PdAu alloy and In2O3 described in this invention is simple to operate, easy to industrialize, and conducive to the large-scale production and application of sensors. Attached Figure Description

[0033] Figure 1 This is a scanning electron microscope image of PdAu@In2O3 prepared in Example 1;

[0034] Figure 2 The images show the XRD patterns of PdAu@In2O3 and In2O3 prepared in Example 1. Detailed Implementation

[0035] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0036] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0037] One aspect of the present invention provides a composite material based on PdAu alloy and In2O3, wherein the composite material includes In2O3 and PdAu alloy nanoparticles supported on In2O3.

[0038] In a preferred embodiment, in order to improve the sensitivity of the composite material to hydrogen, the weight ratio of PdAu alloy nanoparticles to In2O3 is 5 to 30:100; specifically, it can be 5:100, 10:100, 16:100, 20:100, 21:100, 22:100, 23:100, 24:100, 25:100 or 30:100.

[0039] In a preferred embodiment, in order to further improve the sensitivity of the composite material to hydrogen, the particle size of the PdAu alloy nanoparticles is 5-15 nm, thereby giving the composite material a large specific surface area and providing more hydrogen active sites.

[0040] In a preferred embodiment, the molar ratio of Pd to Au in the PdAu alloy nanoparticles is 1 to 3:1; specifically, it can be 1:1, 1.5:1, 2:1, 2.5:1 or 3:1.

[0041] The composite material based on PdAu alloy and In2O3 described in this invention has good electrical conductivity and stability, as well as good sensitivity and response to hydrogen. This is mainly because PdAu alloy nanoparticles have a large specific surface area, which can act as active sites to quickly adsorb and dissociate H2, while In2O3 itself has good stability and surface activity.

[0042] A second aspect of the present invention provides a method for preparing a composite material based on PdAu alloy and In2O3, the method comprising the following steps:

[0043] (1) The precursor solution, In2O3 and reducing agent are mixed and the first reaction is carried out;

[0044] (2) The material obtained in step (1) is subjected to solid-liquid separation, and then the obtained solid intermediate material A is dried and calcined for the first time;

[0045] In step (1), the precursor solution contains Pd precursor and Au precursor.

[0046] In this invention, the precursor solution is an aqueous precursor solution, which is obtained by mixing Pd precursor, Au precursor and water.

[0047] In this invention, there are no special requirements for the Pd precursor and Au precursor, and any commonly used ones in the art are acceptable. For example, the Pd precursor can be chloropalladium acid, and the Au precursor can be chloroauric acid.

[0048] In a preferred embodiment, in order to improve the sensitivity of the composite material to hydrogen, in step (1), the ratio of the total weight of the Pd precursor and the Au precursor to the weight of In2O3 is 1 to 5:10, wherein both the Pd precursor and the Au precursor are calculated as metals; specifically, it can be 1:10, 3:10 or 5:10.

[0049] In a preferred embodiment, in step (1), the molar ratio of the amount of Pd precursor to Au precursor is 1 to 3:1, wherein both Pd precursor and Au precursor are calculated as metals; specifically, it can be 1:1, 1.5:1, 2:1, 2.5:1 or 3:1.

[0050] In a preferred embodiment, in step (1), the total weight ratio of the Pd precursor and the Au precursor to the reducing agent is 1:5 to 50, wherein both the Pd precursor and the Au precursor are based on metals; specifically, it can be 1:5, 1:10, 1:15, 1:20, 1:30, 1:40 or 1:50.

[0051] In this invention, there are no special requirements for the type of reducing agent, as long as it can reduce the Pd precursor and Au precursor to the corresponding metal element; in a preferred embodiment, in step (1), the reducing agent is selected from one or more of sodium borohydride, ascorbic acid and hydrazine hydrate.

[0052] In a preferred embodiment, in step (1), the conditions for the first reaction include: a temperature of 80 to 150°C and a time of 5 to 20 hours; specifically, the temperature can be 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C; and the time can be 5 hours, 6 hours, 7 hours, 9 hours, 11 hours, 13 hours, 15 hours, or 20 hours.

[0053] In a specific implementation, the specific process of step (1) includes: dispersing In2O3 in water, then adding Pd precursor and Au precursor and stirring, and finally adding a reducing agent to carry out the first reaction.

[0054] In a preferred embodiment, in step (1), the method for preparing In2O3 includes: mixing an In precursor solution, methanol and polyvinylpyrrolidone and then carrying out a second reaction, followed by solid-liquid separation, and drying and second calcining the obtained solid intermediate material B.

[0055] In a preferred embodiment, the conditions for the second reaction to prepare In2O3 include: a temperature of 120–200°C and a time of 3–15 h; specifically, the temperature can be 120°C, 130°C, 140°C, 150°C, 170°C, 190°C, or 200°C; and the time can be 3 h, 4 h, 5 h, 6 h, 7 h, 9 h, 11 h, 13 h, or 15 h.

[0056] In a preferred embodiment, the conditions for the second calcination of In2O3 include: a temperature of 450–600°C and a time of 3–24 h; specifically, the temperature can be 450°C, 470°C, 500°C, 520°C, 550°C, or 600°C; and the time can be 3 h, 4 h, 5 h, 6 h, 7 h, 9 h, 11 h, 13 h, 15 h, 17 h, 20 h, or 24 h.

[0057] In a preferred embodiment, the weight ratio of In precursor, methanol, and polyvinylpyrrolidone in the In precursor solution is 1:8 to 20:40 to 80, wherein the In precursor is calculated as In element; specifically, it can be 1:8:40, 1:15:40, 1:20:40, 1:8:60, 1:15:60, 1:20:60, 1:8:80, 1:15:80, or 1:20:80.

[0058] In this invention, there are no special requirements for the In precursor solution; any solution conventionally used in the art is acceptable, such as an In(NO3)3·4.5H2O solution.

[0059] In a preferred embodiment, the In precursor solution is an aqueous solution of the In precursor, obtained by mixing the In precursor and water.

[0060] In a specific embodiment, the preparation method of In2O3 specifically includes: mixing methanol and polyvinylpyrrolidone, then adding In precursor and water, transferring it to a reaction vessel for a second reaction, then performing solid-liquid separation, and drying and second calcining the obtained solid intermediate material B.

[0061] In a preferred embodiment, the conditions for the first calcination in step (2) include: a temperature of 400-600°C and a time of 5-20h; specifically, the temperature can be 400°C, 420°C, 450°C, 470°C, 500°C, 520°C, 550°C or 600°C; and the time can be 5h, 6h, 7h, 9h, 11h, 13h, 15h, 17h or 20h.

[0062] In this invention, both the "first calcination" and the "second calcination" are carried out in the presence of oxygen.

[0063] In this invention, there are no special requirements for the solid-liquid separation and drying conditions; any conditions conventionally applicable in the art are acceptable.

[0064] A third aspect of the present invention provides a composite material based on PdAu alloy and In2O3 prepared by the above method.

[0065] The composite material based on PdAu alloy and In2O3 prepared by the above method has good electrical conductivity and stability, as well as good sensitivity and response to hydrogen. This is mainly because the PdAu alloy nanoparticles prepared by the above method have a large specific surface area, which can act as active sites to quickly adsorb and dissociate H2, while In2O3 itself has good stability and surface activity.

[0066] The fourth aspect of this invention provides the application of the above-mentioned composite material based on PdAu alloy and In2O3 in hydrogen detection.

[0067] The composite material based on PdAu alloy and In2O3 described in this invention has high sensitivity to hydrogen and can directly address the problem of hydrogen leakage monitoring and detection in the atmospheric environment. It can detect leaked hydrogen in the environment with high selectivity and speed at room temperature, reduce the hazards caused by hydrogen leakage, and thus ensure the safety of personnel, environment and equipment.

[0068] A fifth aspect of the present invention provides a hydrogen sensor comprising the aforementioned composite material based on PdAu alloy and In2O3.

[0069] The sixth aspect of the present invention provides a method for preparing the above-mentioned hydrogen sensor, the method comprising: mixing and grinding the above-mentioned composite material based on PdAu alloy and In2O3 with an organic solvent, then coating it onto the surface of a ceramic tube with electrodes and performing heat treatment.

[0070] In a preferred embodiment, in order to improve the sensitivity and selectivity of the hydrogen sensor, the heat treatment conditions include: a temperature of 60–100°C and a time of 2–20 h; specifically, the temperature can be 60°C, 70°C, 80°C, 90°C, or 100°C; and the time can be 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, or 20 h.

[0071] In a preferred embodiment, the weight-to-volume ratio of the composite material based on PdAu alloy and In2O3 to the organic solvent is 1000-2000 mg: 1 mL. Based on this, the dispersion will not be too thin to coat due to excessive use of organic solvent, nor will the dispersion be too thick due to insufficient use of organic solvent, resulting in uneven coating and affecting the gas-sensing performance of the hydrogen sensor.

[0072] In this invention, there are no special requirements for the organic solvent; any commonly used solvent in the art is acceptable, such as ethanol, acetone, glycerol, or terpineol.

[0073] A seventh aspect of the present invention provides a method for detecting hydrogen, the method comprising contacting the above-mentioned composite material based on PdAu alloy and In2O3 with a mixed gas containing hydrogen.

[0074] In a preferred embodiment, in order to improve the detection accuracy of the hydrogen sensor, the volume content of hydrogen in the mixed gas is 0.01% to 50%; specifically, the volume content of hydrogen can be 0.01%, 0.05%, 1%, 5%, 10%, 20%, 30%, 40%, or 50%.

[0075] The following examples further illustrate the composite material based on PdAu alloy and In2O3, its preparation method, and its application according to the present invention. The examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0076] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials and instruments used in the following embodiments are commercially available, including the scanning electron microscope (SEM) and the energy dispersive spectroscopy (EDS) spectrometer (EDS).

[0077] Example 1

[0078] Preparation of In2O3(S1):

[0079] 10g of polyvinylpyrrolidone was added to 40g of methanol and stirred for 60min. Then, 2g of In(NO3)3·4.5H2O was added and stirred for 30min. Then, 50μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 180℃ for 5h. After cooling and centrifugation, the obtained solid intermediate material B1 was washed with methanol and dried at 80℃ for 10h. Then, it was placed in a muffle furnace for a second calcination at 500℃ for 4h to obtain In2O3(S1).

[0080] Preparation of PdAu@In2O3 (M1):

[0081] (1) Disperse 0.5gIn2O3(S1) in 50mL of water and sonicate for 60min. Then add 0.2g of a mixture of chloropalladic acid and chloroauric acid (molar ratio of chloropalladic acid and chloroauric acid is 1:1) and stir for 4h. Finally, add 1g of sodium borohydride to carry out the first reaction. The temperature of the first reaction is 100℃ and the time of the first reaction is 6h.

[0082] (2) The material obtained in step (1) was centrifuged to separate the solid and liquid phases. Then, the obtained solid intermediate material A1 was washed with deionized water and ethanol, dried in air at 80°C for 10 hours, and finally placed in a muffle furnace for the first calcination at 400°C for 5 hours to obtain PdAu@In2O3(M1) (its microstructure is as follows). Figure 1 (as shown);

[0083] Preparation of PdAu@In2O3 sensor (N1):

[0084] Take 1 mg of PdAu@In2O3 (M1) and place it in a mortar. Add 1 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 60°C for 5 h in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N1) is obtained.

[0085] Example 2

[0086] Preparation of In2O3(S2):

[0087] 18g of polyvinylpyrrolidone was added to 80g of methanol and stirred for 40min. Then, 4g of In(NO3)3·4.5H2O was added and stirred for 20min. Then, 35μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 140℃ for 6h. After cooling and centrifugation, the obtained solid intermediate material B2 was washed with methanol and dried at 80℃ for 8h. Then, it was placed in a muffle furnace for a second calcination at 450℃ for 8h to obtain In2O3(S2).

[0088] Preparation of PdAu@In2O3(M2):

[0089] (1) Disperse 0.5gIn2O3(S2) in 60mL of water and sonicate for 30min. Then add 0.25g of a mixture of chloropalladic acid and chloroauric acid (molar ratio of chloropalladic acid and chloroauric acid is 1:1) and stir for 2h. Finally, add 1.5g of sodium borohydride to carry out the first reaction. The temperature of the first reaction is 80℃ and the time of the first reaction is 6h.

[0090] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A2 is then washed with deionized water and ethanol, dried in air at 70°C for 5 hours, and finally placed in a muffle furnace for the first calcination at 500°C for 4 hours to obtain PdAu@In2O3(M2).

[0091] Preparation of PdAu@In2O3 sensor (N2):

[0092] Take 2 mg of PdAu@In2O3 (M2) and place it in a mortar. Add 4 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 80°C for 5 h in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N2) is obtained.

[0093] Example 3

[0094] Preparation of In2O3(S3):

[0095] 4g of polyvinylpyrrolidone was added to 35g of methanol and stirred for 40min. Then, 1.8g of In(NO3)3·4.5H2O was added and stirred for 30min. Then, 30μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 140℃ for 4h. After cooling and centrifugation, the obtained solid intermediate material B3 was washed with methanol and dried at 70℃ for 5h. Then, it was placed in a muffle furnace for a second calcination at 380℃ for 6h to obtain In2O3(S3).

[0096] Preparation of PdAu@In2O3 (M3):

[0097] (1) Disperse 0.5gIn2O3(S3) in 40mL of water and sonicate for 30min. Then add 0.17g of a mixture of chloropalladic acid and chloroauric acid (the molar ratio of chloropalladic acid and chloroauric acid is 1:1) and stir for 2h. Finally, add 3g of sodium borohydride to carry out the first reaction. The temperature of the first reaction is 140℃ and the time of the first reaction is 7h.

[0098] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A3 is then washed with deionized water and ethanol, dried in air at 60°C for 7 hours, and finally placed in a muffle furnace for the first calcination at 500°C for 6 hours to obtain PdAu@In2O3(M3).

[0099] Preparation of PdAu@In2O3 sensor (N3):

[0100] Take 1 mg of PdAu@In2O3 (M3) and place it in a mortar. Add 1.5 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 60°C for 6 hours in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N3) is obtained.

[0101] Example 4

[0102] Preparation of In2O3(S4):

[0103] 5.5 g of polyvinylpyrrolidone was added to 45 g of methanol and stirred for 50 min. Then, 2.5 g of In(NO3)3·4.5H2O was added and stirred for 30 min. Then, 40 μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 140 °C for 8 h. After cooling and centrifugation, the obtained solid intermediate material B4 was washed with methanol and dried at 60 °C for 5 h. Then, it was placed in a muffle furnace for a second calcination at 500 °C for 6 h to obtain In2O3(S4).

[0104] Preparation of PdAu@In2O3(M4):

[0105] (1) Disperse 0.5gIn2O3(S4) in 40mL of water and sonicate for 20min. Then add 0.3g of a mixture of chloropalladic acid and chloroauric acid (molar ratio of chloropalladic acid to chloroauric acid is 1.5:1) and stir for 2.5h. Finally, add 2.5g of sodium borohydride to carry out the first reaction. The temperature of the first reaction is 120℃ and the time of the first reaction is 5h.

[0106] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A4 is then washed with deionized water and ethanol, dried in air at 60°C for 6 hours, and finally placed in a muffle furnace for the first calcination at 400°C for 5 hours to obtain PdAu@In2O3(M4).

[0107] Preparation of PdAu@In2O3 sensor (N4):

[0108] Take 2 mg of PdAu@In2O3 (M4) and place it in a mortar. Add 4 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 70°C for 3 h in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N4) is obtained.

[0109] Example 5

[0110] Preparation of In2O3(S5):

[0111] 7g of polyvinylpyrrolidone was added to 55g of methanol and stirred for 40min. Then, 3.2g of In(NO3)3·4.5H2O was added and stirred for 30min. Then, 60μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 140℃ for 6h. After cooling and centrifugation, the obtained solid intermediate material B5 was washed with methanol and dried at 60℃ for 12h. Then, it was placed in a muffle furnace for a second calcination at 500℃ for 4h to obtain In2O3(S5).

[0112] Preparation of PdAu@In2O3 (M5):

[0113] (1) Disperse 0.5gIn2O3(S5) in 80mL of water and sonicate for 60min. Then add 0.3g of a mixture of chloropalladic acid and chloroauric acid (the molar ratio of chloropalladic acid and chloroauric acid is 1:1) and stir for 4h. Finally, add 2g of sodium borohydride to carry out the first reaction. The temperature of the first reaction is 100℃ and the time of the first reaction is 7h.

[0114] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A5 is then washed with deionized water and ethanol, dried in air at 70°C for 10 hours, and finally placed in a muffle furnace for the first calcination at 400°C for 7 hours to obtain PdAu@In2O3(M5).

[0115] Preparation of PdAu@In2O3 sensor (N5):

[0116] Take 3 mg of PdAu@In2O3 (M5) and place it in a mortar. Add 5 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 60°C for 5 h in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N5) is obtained.

[0117] Example 6

[0118] Preparation of In2O3(S6):

[0119] 8g of polyvinylpyrrolidone was added to 60g of methanol and stirred for 45min. Then, 3.5g of In(NO3)3·4.5H2O was added and stirred for 40min. Then, 30μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 140℃ for 6h. After cooling and centrifugation, the obtained solid intermediate material B6 was washed with methanol and dried at 70℃ for 12h. Then, it was placed in a muffle furnace for a second calcination at 500℃ for 7h to obtain In2O3(S6).

[0120] Preparation of PdAu@In2O3(M6):

[0121] (1) Disperse 0.5g In2O3(S6) in 45g water and sonicate for 45min. Then add 0.23g of a mixture of chloropalladic acid and chloroauric acid (the molar ratio of chloropalladic acid and chloroauric acid is 2:1) and stir for 4h. Finally, add 3g sodium borohydride to carry out the first reaction. The temperature of the first reaction is 110℃ and the time of the first reaction is 6h.

[0122] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A6 is then washed with deionized water and ethanol, dried in air at 80°C for 5 hours, and finally placed in a muffle furnace for the first calcination at 500°C for 6 hours to obtain PdAu@In2O3(M6).

[0123] Preparation of PdAu@In2O3 sensor (N6):

[0124] Take 1 mg of PdAu@In2O3 (M6) and place it in a mortar. Add 2 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 80°C for 6 hours in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N6) is obtained.

[0125] Example 7

[0126] Preparation of In2O3(S7):

[0127] 6g of polyvinylpyrrolidone was added to 30g of methanol and stirred for 45min. Then, 1.5g of In(NO3)3·4.5H2O was added and stirred for 40min. Then, 40μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 130℃ for 8h. After cooling and centrifugation, the obtained solid intermediate material B7 was washed with methanol and dried at 60℃ for 7h. Then, it was placed in a muffle furnace for a second calcination at 500℃ for 6h to obtain In2O3(S7).

[0128] Preparation of PdAu@In2O3 (M7):

[0129] (1) Disperse 0.5gIn2O3(S7) in 50mL of water and sonicate for 50min. Then add 0.2g of a mixture of chloropalladic acid and chloroauric acid (the molar ratio of chloropalladic acid and chloroauric acid is 2:1) and stir for 4h. Finally, add 2.5g of sodium borohydride to carry out the first reaction. The temperature of the first reaction is 110℃ and the time of the first reaction is 6h.

[0130] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A7 is then washed with deionized water and ethanol, dried in air at 60°C for 7 hours, and finally placed in a muffle furnace for the first calcination at 400°C for 5 hours to obtain PdAu@In2O3(M7).

[0131] Preparation of PdAu@In2O3 sensor (N7):

[0132] Take 1 mg of PdAu@In2O3 (M7) and place it in a mortar. Add 1 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 60°C for 6 hours in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N7) is obtained.

[0133] Example 8

[0134] Preparation of In2O3(S8):

[0135] 8g of polyvinylpyrrolidone was added to 60g of methanol and stirred for 40min. Then, 3g of In(NO3)3·4.5H2O was added and stirred for 40min. Then, 40μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 170℃ for 4h. After cooling and centrifugation, the obtained solid intermediate material B8 was washed with methanol and dried at 80℃ for 7h. Then, it was placed in a muffle furnace for a second calcination at 450℃ for 5h to obtain In2O3(S8).

[0136] Preparation of PdAu@In2O3(M8):

[0137] (1) Disperse 0.5gIn2O3(S8) in 60mL of water and sonicate for 50min. Then add 0.3g of a mixture of chloropalladic acid and chloroauric acid (the molar ratio of chloropalladic acid and chloroauric acid is 1:1) and stir for 2h. Finally, add 2g of ascorbic acid to carry out the first reaction. The temperature of the first reaction is 100℃ and the time of the first reaction is 7h.

[0138] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A8 is then washed with deionized water and ethanol, dried in air at 60°C for 10 hours, and finally placed in a muffle furnace for the first calcination at 400°C for 6 hours to obtain PdAu@In2O3(M8).

[0139] Preparation of PdAu@In2O3 sensor (N8):

[0140] Take 2 mg of PdAu@In2O3 (M8) and place it in a mortar. Add 5 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 60°C for 5 h in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N8) is obtained.

[0141] Example 9

[0142] Preparation of In2O3(S9):

[0143] 5.5 g of polyvinylpyrrolidone was added to 40 g of methanol and stirred for 45 min. Then, 2.4 g of In(NO3)3·4.5H2O was added and stirred for 30 min. Then, 45 μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 160 °C for 7 h. After cooling and centrifugation, the obtained solid intermediate material B9 was washed with methanol and dried at 60 °C for 5 h. Then, it was placed in a muffle furnace for a second calcination at 500 °C for 4 h to obtain In2O3(S9).

[0144] Preparation of PdAu@In2O3(M9):

[0145] (1) Disperse 0.5gIn2O3(S9) in 65mL of water and sonicate for 45min. Then add 0.25g of a mixture of chloropalladic acid and chloroauric acid (molar ratio of chloropalladic acid and chloroauric acid is 1:1) and stir for 3h. Finally, add 1.6g of hydrazine hydrate to carry out the first reaction. The temperature of the first reaction is 90℃ and the time of the first reaction is 6h.

[0146] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A9 is then washed with deionized water and ethanol, dried in air at 70°C for 5 hours, and finally placed in a muffle furnace for the first calcination at 600°C for 6 hours to obtain PdAu@In2O3(M9).

[0147] Preparation of PdAu@In2O3 sensor (N9):

[0148] Take 1.5 mg of PdAu@In2O3 (M9) and place it in a mortar. Add 3 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 70 °C for 6 h in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N9) is obtained.

[0149] Example 10

[0150] Preparation of In2O3(S10):

[0151] 3g of polyvinylpyrrolidone was added to 16g of methanol and stirred for 30min. Then, 1g of In(NO3)3·4.5H2O was added and stirred for 10min. Then, 25μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 150℃ for 7h. After cooling and centrifugation, the obtained solid intermediate material B10 was washed with methanol and dried at 60℃ for 6h. Then, it was placed in a muffle furnace for a second calcination at 450℃ for 6h to obtain In2O3(S10).

[0152] Preparation of PdAu@In2O3(M10):

[0153] (1) Disperse 0.5gIn2O3(S10) in 60mL of water and sonicate for 50min. Then add 0.3g of a mixture of chloropalladic acid and chloroauric acid (the molar ratio of chloropalladic acid and chloroauric acid is 1:1) and stir for 3h. Finally, add 3g of sodium borohydride to carry out the first reaction. The temperature of the first reaction is 110℃ and the time of the first reaction is 8h.

[0154] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. The solid intermediate material A10 is then washed with deionized water and ethanol, dried in air at 60°C for 6 hours, and finally placed in a muffle furnace for the first calcination at 400°C for 8 hours to obtain PdAu@In2O3(M10).

[0155] Preparation of PdAu@In2O3 sensor (N10):

[0156] Take 2 mg of PdAu@In2O3 (M10) and place it in a mortar. Add 3 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 70°C for 5 h in an inert gas atmosphere. After naturally cooling to room temperature, the PdAu@In2O3 sensor (N10) is obtained.

[0157] Example 11

[0158] The implementation was carried out in accordance with Example 1, except that the weight of In2O3 was 5g.

[0159] Example 12

[0160] The method was implemented in accordance with Example 1, except that the weight of sodium borohydride was 0.1.

[0161] Example 13

[0162] The implementation was carried out in accordance with Example 1, except that the molar ratio of chloropalladic acid to chloroauric acid was 4:1.

[0163] Comparative Example 1

[0164] Preparation of In2O3(S1):

[0165] 8g of polyvinylpyrrolidone was added to 30g of methanol and stirred for 60min. Then, 2g of In(NO3)3·4.5H2O was added and stirred for 30min. Then, 50μL of deionized water was added, and the mixture was transferred to a reaction vessel and sealed. The reaction was carried out at 180℃ for 5h. After cooling and centrifugation, the mixture was washed with methanol and dried at 80℃ for 10h. Then, it was placed in a muffle furnace for a second calcination at 500℃ for 2h to obtain In2O3(S1).

[0166] Preparation of In2O3 sensor (N13):

[0167] Take 1 mg of In2O3 (S1) and place it in a mortar. Add 1 μL of terpineol and grind it evenly. Then coat it onto the surface of a ceramic tube with electrodes. Then heat-treat it at 60°C for 5 h in an inert gas atmosphere. After naturally cooling to room temperature, the In2O3 sensor (N13) is obtained.

[0168] Comparative Example 2

[0169] Preparation of PdAu alloy nanoparticles:

[0170] (1) Add 0.2g of a mixture of chloropalladic acid and chloroauric acid (the molar ratio of chloropalladic acid and chloroauric acid is 1:1) to 50mL of water and stir for 4h. Then add 1g of sodium borohydride to react. The reaction temperature is 100℃ and the reaction time is 6h.

[0171] (2) The material obtained in step (1) is separated into solid and liquid by centrifugation. Then the solid intermediate material is washed with deionized water and ethanol, dried in air at 80°C for 10 hours, and finally placed in a muffle furnace for calcination at 450°C for 5 hours to obtain PdAu alloy nanoparticles.

[0172] Fabrication of PdAu alloy nanoparticle sensor (N13):

[0173] 1 mg of PdAu alloy nanoparticles were placed in a mortar, 1 μL of terpineol was added, and after grinding evenly, the mixture was coated onto the surface of a ceramic tube with electrodes. Then, the tube was heat-treated at 60 °C for 5 h in an inert gas atmosphere. After naturally cooling to room temperature, a PdAu alloy nanoparticle sensor (N14) was obtained.

[0174] Comparative Example 3

[0175] The procedure was carried out in accordance with Example 1, except that step (1) did not contain the raw material chloropalladium acid, and the amount of sodium borohydride used was 0.5g.

[0176] Comparative Example 4

[0177] The procedure was carried out in accordance with Example 1, except that step (1) did not contain the raw material chloroauric acid, and the amount of sodium borohydride used was 0.5g.

[0178] Test case

[0179] (1) The diffraction peaks of PdAu@In2O3 prepared in Example 1 were tested using an X-ray diffractometer. Figure 2 These are the XRD patterns of In2O3 and PdAu@In2O3 prepared in Example 1;

[0180] Depend on Figure 2 It can be seen that PdAu@In2O3 contains both diffraction peaks of PdAu alloy nanoparticles and diffraction peaks of In2O3, indicating that PdAu alloy nanoparticles are loaded onto In2O3 to form a composite material.

[0181] (2) The samples prepared in the examples and comparative examples were subjected to semi-quantitative EDS energy dispersive spectroscopy analysis using an energy dispersive spectroscopy instrument to calculate the loading of PdAu alloy nanoparticles. The results are shown in Table 1.

[0182] (3) The sensing performance of the sensors prepared in the examples and comparative examples was tested. The sensors were placed in hydrogen gas of different volume concentrations and the changes in their resistance values ​​were measured. The results are shown in Table 1. The response intensity of the sensors prepared in Example 1 and Comparative Examples 1-2 to different concentrations of hydrogen gas is shown in Table 2.

[0183] (4) Test the response of the sensor prepared in Example 1 to interfering gases, including hydrogen sulfide, methane, carbon monoxide or nitric oxide.

[0184] The sensor prepared in Example 1 was placed in hydrogen sulfide gas of different volume concentrations. The results showed that, at the same volume concentration, the response intensity of hydrogen sulfide was only 2% of that of hydrogen. The sensor prepared in Example 1 was placed in methane gas of different volume concentrations. The results showed that, at the same volume concentration, the response intensity of methane was only 1.8% of that of hydrogen. The sensor prepared in Example 1 was placed in carbon monoxide gas of different volume concentrations. The results showed that, at the same volume concentration, the response intensity of carbon monoxide was only 0.9% of that of hydrogen. The sensor prepared in Example 1 was placed in nitric oxide gas of different volume concentrations. The results showed that, at the same volume concentration, the response intensity of nitric oxide was only 1.2% of that of hydrogen.

[0185] The above results indicate that the sensor prepared by PdAu@In2O3 according to the present invention is selective for gases, and only has high sensitivity and fast response when the detected gas is hydrogen.

[0186] Table 1

[0187]

[0188]

[0189] Table 2

[0190]

[0191] As can be seen from the results in Tables 1 and 2, when the composite material based on PdAu alloy and In2O3 described in this invention is used in the sensor, it can operate at room temperature and has high sensitivity, a wide range of detectable H2 volume content, and a low detection limit.

[0192] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composite material based on PdAu alloy and In2O3, characterized in that, The composite material based on PdAu alloy and In2O3 includes In2O3 and PdAu alloy nanoparticles supported on In2O3.

2. The composite material based on PdAu alloy and In2O3 according to claim 1, characterized in that, The weight ratio of PdAu alloy nanoparticles to In2O3 is 5–30:

100.

3. The composite material based on PdAu alloy and In2O3 according to claim 1 or 2, characterized in that, The particle size of the PdAu alloy nanoparticles is 5-15 nm.

4. The composite material based on PdAu alloy and In2O3 according to claim 3, characterized in that, The molar ratio of Pd to Au in PdAu alloy nanoparticles is 1 to 3:

1.

5. A method for preparing a composite material based on a PdAu alloy and In2O3, characterized in that, The method includes the following steps: (1) The precursor solution, In2O3 and reducing agent are mixed and the first reaction is carried out; (2) The material obtained in step (1) is subjected to solid-liquid separation, and then the obtained solid intermediate material A is dried and calcined for the first time; In step (1), the precursor solution contains Pd precursor and Au precursor.

6. The method of claim 5, wherein, In step (1), the ratio of the total weight of Pd precursor and Au precursor to the weight of In2O3 is 1 to 4:10, wherein both Pd precursor and Au precursor are calculated as metals.

7. The method according to claim 5 or 6, characterized in that, In step (1), the molar ratio of Pd precursor to Au precursor is 1 to 3:1, wherein both Pd precursor and Au precursor are calculated as metals.

8. The method according to any one of claims 5-7, characterized in that, In step (1), the total weight ratio of Pd precursor and Au precursor to reducing agent is 1:5 to 50, wherein both Pd precursor and Au precursor are calculated as metals.

9. The method of claim 8, wherein, In step (1), the conditions for the first reaction include: a temperature of 80 to 150°C and a time of 5 to 20 hours.

10. The method of claim 5, wherein, In step (1), the preparation method of In2O3 includes: mixing In precursor solution, methanol and polyvinylpyrrolidone and carrying out a second reaction, then performing solid-liquid separation, and drying and second calcining the obtained solid intermediate material B.

11. The method of claim 10, wherein, The conditions for the second reaction include a temperature of 120–200°C and a time of 3–15 hours.

12. The method according to claim 10, characterized in that, The conditions for the second calcination include: a temperature of 450–600℃ and a time of 3–24 hours.

13. The method according to claim 10, characterized in that, The weight ratio of In precursor, methanol, and polyvinylpyrrolidone in the In precursor solution is 1:8-20:40-80, where the In precursor is calculated as In element.

14. The method according to any one of claims 5-13, characterized in that, In step (1), the reducing agent is selected from one or more of sodium borohydride, ascorbic acid and hydrazine hydrate.

15. The method of claim 5, wherein, In step (2), the conditions for the first calcination include: a temperature of 400-600℃ and a time of 5-20h.

16. The composite material based on PdAu alloy and In2O3 prepared by the method of any one of claims 5-15.

17. The application of the composite material based on PdAu alloy and In2O3 as described in any one of claims 1-4 and 16 in hydrogen detection.

18. A hydrogen sensor, characterized by The hydrogen sensor comprises the composite material based on PdAu alloy and In2O3 as described in any one of claims 1-4 and 16.

19. A method of making the hydrogen sensor of claim 18, wherein, The method includes: mixing and grinding the composite material based on PdAu alloy and In2O3 as described in any one of claims 1-4 and 16 with an organic solvent, then coating it onto the surface of a ceramic tube with electrodes and performing heat treatment.

20. The method of claim 19, wherein, The heat treatment conditions include a temperature of 60–100℃ and a time of 2–20 hours.

21. A method of hydrogen detection, comprising: The method involves contacting the composite material based on PdAu alloy and In2O3 as described in any one of claims 1-4 and 16 with a mixed gas containing hydrogen.

22. The method of claim 21, wherein, The volume content of hydrogen in the gas mixture is 0.01% to 50%.

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