Platinum monoxide-tungsten trioxide composite nanomaterial and preparation method and gas-sensitive application thereof

Abstract

The invention discloses a PtO-WO3 composite nanomaterial, a preparation method thereof and a gas-sensitive application thereof, and the method is realized by preparing a base material by adopting a hydrothermal method and further preparing the composite nanomaterial by combining an impregnation method with a calcination technology. Compared with the prior art, the preparation method has the advantages that tedious steps are not needed, the preparation technology of the PtO modified WO3 nano material is realized, and the material has the characteristic of high gas sensitivity. The PtO-WO3 composite nanomaterial prepared by combining a reasonably designed load ratio with calcination treatment realizes efficient detection of hydrogen, and the mechanism can be attributed to the catalytic action of PtO and the synergistic effect between PtO and WO3. The method provided by the invention is simple and convenient, and can provide reference for a large-scale preparation technology corresponding to the hydrogen sensitive material.

Description

Technical Field

[0001] The invention belongs to the field of nano material preparation technology and application, and specifically relates to a platinum monoxide-tungsten trioxide (PtO-WO3) composite nano material and a preparation method and gas-sensitive application thereof. Background Art

[0002] Compared with diesel, natural gas, propane, etc., hydrogen is an energy with high energy density. At the same time, its combustion has no carbon emissions and has environmental advantages. Leakage may occur during the production, transportation, and storage of hydrogen. The energy of hydrogen ignited in the air is only 0.02mJ, and the lower explosion limit is about 4%. At the same time, hydrogen itself is colorless and odorless and difficult to detect. Its flammable and explosive characteristics bring great hidden dangers to production or life and property safety. Therefore, real-time monitoring of hydrogen is very necessary.

[0003] WO3 is a typical n-type semiconductor material, which plays an important role in detecting organic volatile gases and combustible gases. However, pure WO3 nanomaterials have disadvantages such as low sensitivity and high operating temperature in detecting target gases. Researchers have found that surface modification of pure WO3 nanomaterials can improve the gas-sensing performance of pure WO3 nanomaterials to target gases. For example, Wang et al. (Sensors and Actuators B: Chemical, 156 (2011) 918-923) reported that surface modification of WO3 nanomaterials using Pt can significantly improve the gas-sensing performance of pure WO3. However, sodium borohydride is required as a reducing agent to prepare Pt single substance in the preparation process of the composite material, which has the disadvantage of a relatively cumbersome preparation process. Chinese invention patent (CN116297244A) discloses a Pt / WO3 material based on a metal organic framework template, a preparation method thereof, and a hydrogen sensor, but the material preparation process still has the disadvantage of being complicated. Therefore, it is necessary to develop a PtO-WO3 composite nanomaterial with a simple preparation method and excellent gas-sensing performance. And there are no reports on the preparation of PtO-WO3 composite nanomaterials and their application in detecting hydrogen. Summary of the invention

[0004] The invention discloses a PtO-WO3 composite nano material and a preparation method and gas-sensitive application thereof. The material preparation process in the method is simple and easy to operate, and the obtained composite material exhibits excellent performance in detecting hydrogen.

[0005] The technical solution of the present invention is as follows:

[0006] A preparation method of a PtO-WO3 composite nanomaterial comprises the following contents: preparing a basic WO3 nanomaterial, usually a nano-block material, by a hydrothermal method, and further preparing the PtO-WO3 composite nanomaterial by an impregnation method and a calcination treatment, specifically:

[0007] A certain amount of tungsten source and a certain amount of deionized water are mixed, and a certain volume of hydrochloric acid is further added thereto. The mixed solution is placed in a high-pressure reactor for hydrothermal reaction and then collected to obtain a WO3 powder sample; a certain amount of WO3 powder sample and a certain concentration of platinum source are taken for impregnation according to different PtO and WO3 mass ratios, and the sample is further collected by centrifugation and dried, and then calcined at a certain temperature to finally obtain a PtO-WO3 composite nanomaterial.

[0008] In the above technical solution, preferably, the tungsten source is selected as sodium tungstate dihydrate.

[0009] Preferably, in the hydrothermal method, the volume of hydrochloric acid to the volume of deionized water is 1:2 to 5:1, more preferably 1:1.

[0010] Preferably, the hydrothermal reaction temperature is 140-200° C., and the hydrothermal time is 12-24 h; more preferably, it is 180° C. and the time is 12 h.

[0011] Preferably, the different mass ratios of PtO and WO3 are as follows: the mass ratio of PtO to WO3 is 0.28-7.8%, more preferably 0.84%.

[0012] Preferably, the impregnation operation is to disperse the basic WO3 nanocube powder in deionized water, drop chloroplatinic acid solution into it and keep it at 80-100°C for 10-20 minutes, preferably at 95°C for 15 minutes.

[0013] Preferably, the drying temperature is 50-90° C., and the drying time is 6-24 hours.

[0014] Preferably, the calcination temperature is 300-400°C, more preferably 350°C.

[0015] Preferably, the calcination time is 1 to 2 hours.

[0016] Preferably, the heating rate during the calcination process is set to 1-2°C / min.

[0017] In the PtO-WO3 composite nano material prepared by the invention, WO3 is a nano cube material, and a dotted material is modified on its surface. The surface modification component is PtO, and no other impurities exist.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention prepares the basic WO3 nanomaterial by hydrothermal method, the hydrothermal parameters are simple and the repeatability is good. The WO3-based composite nanomaterial with PtO surface modification is prepared by impregnation combined with calcination treatment, the preparation process is simple and the loading agent ratio is controllable.

[0020] 2. The PtO-WO3 composite nanomaterial of the present invention can realize efficient detection of hydrogen, with a detection limit of ppb level; the response time to 100 ppm hydrogen is ultra-fast (about 1 second). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a SEM image of the PtO-WO3 composite nanomaterial described in Example 1;

[0022] Figure 2 is a TEM image of the PtO-WO3 composite nanomaterial described in Example 1;

[0023] Figure 3 is a curve diagram of the response value of the composite nanomaterial described in Example 2 to different concentrations of hydrogen;

[0024] Figure 4 is a graph showing the response and recovery of the composite nanomaterial to 100 ppm hydrogen in Example 2;

[0025] Figure 5 is a SEM image of the sample obtained by the hydrothermal method described in Comparative Example 1;

[0026] Figure 6 This is the response curve of the sample described in Comparative Example 2 to 100 ppm hydrogen at 200°C. DETAILED DESCRIPTION

[0027] The technical solutions and effects of the present invention are further described in detail below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0028] Example 1

[0029] A PtO-WO3 composite nanomaterial and its preparation method and gas sensing application, the preparation method comprises the following steps:

[0030] (1) Preparation of basic WO3 material: Weigh 2.3 g of sodium tungstate dihydrate and dissolve it in 30 mL of deionized water, and stir for 30 min. Then, weigh 30 mL of HCl solution with a mass fraction of about 37% and add it to the mixture, and continue stirring for 30 min. The speed is set to 500 rpm / min.

[0031] Further, the obtained mixed solution was subjected to a hydrothermal reaction. The hydrothermal parameters were as follows: the temperature was set at 180°C and the heat preservation time was 12 hours. After natural cooling, the precipitate was centrifuged and washed three times with water, and then dried at 60°C for 12 hours.

[0032] (2) Preparation of PtO-WO3 composite nanomaterials: Weigh 75 mg of the basic WO3 powder dried in the previous step, disperse it in 30 mL of deionized water and ultrasonicate for 15 minutes (marked as mixed solution A). Take 1400 uL of 0.01 mol / L chloroplatinic acid solution and drop it into the above mixed solution A, and keep it at 95°C for 15 minutes under stirring. After natural cooling, centrifuge and wash with water and dry at 60°C for 12 hours. The dried powder sample is placed in a tube furnace and calcined at 350°C for 2 hours in an air atmosphere, and the heating rate is set to 2°C / min.

[0033] (3) Characterization of morphology and gas-sensing performance: The material obtained by high-temperature calcination in the previous step was subjected to SEM testing. The microscopic morphology was a rectangular block with small-sized dot-like substances visible on the surface. TEM results proved that the substrate was WO3 and the small-sized particles on the surface were PtO. The PtO-WO3 composite nanomaterial prepared in the above method was coated on a gold interdigital electrode by a coating method to make a prototype device. The prepared gas-sensitive prototype device was further placed in a CGS-MT optoelectronic integrated test platform for gas-sensing performance testing. Under the working temperature of 200°C, the response value of the PtO-WO3 composite nanomaterial to 100ppm hydrogen was 42.

[0034] Example 2

[0035] A PtO-WO3 composite nanomaterial and its preparation method and gas sensing application, comprising the following steps:

[0036] (1) Preparation of basic WO3 material: The process parameters are the same as those described in step (1) of Example 1.

[0037] (2) Preparation of PtO-WO3 composite nanomaterials: Weigh 75 mg of the basic WO3 powder dried in the previous step, disperse it in 30 mL of deionized water and ultrasonicate for 15 min (marked as mixed solution A). Take 300 uL of 0.01 mol / L chloroplatinic acid solution and drop it into the mixed solution A, and keep it at 95 ° C for 15 min under stirring. After natural cooling, centrifuge and wash with water and dry at 70 ° C for 12 h. The dried powder sample is placed in a tube furnace and calcined at 350 ° C for 1 h in an air atmosphere, and the heating rate is set to 1 ° C / min.

[0038] (3) Characterization of morphology and gas-sensing performance: The material obtained by high-temperature calcination in the previous step was subjected to SEM testing. The microscopic morphology was a rectangular block with small-sized dot-like substances visible on the surface. Under the working temperature of 200°C, the response time of the PtO-WO3 composite nanomaterial to 100ppm hydrogen was only about 1 second, the response value was about 340, and the detection limit of hydrogen could reach 500ppb.

[0039] Example 3

[0040] A PtO-WO3 composite nanomaterial and its preparation method and gas sensing application, comprising the following steps:

[0041] (1) Preparation of basic WO3 material: same as step (1) in Example 1.

[0042] (2) Preparation of PtO-WO3 composite nanomaterials: The same as step (2) in Example 1, except that the amount of chloroplatinic acid solution used is 700uL.

[0043] (3) Characterization of morphology and gas sensing performance: The material obtained by high-temperature calcination in the previous step was subjected to SEM testing. The microscopic morphology was a rectangular block with small-sized dot-like substances visible on the surface. Under the working temperature of 200°C, the response value of the PtO-WO3 composite nanomaterial to 100ppm hydrogen was 130.

[0044] Example 4

[0045] A PtO-WO3 composite nanomaterial and its preparation method and gas sensing application, comprising the following steps:

[0046] (1) Preparation of basic WO3 material: same as step (1) in Example 1.

[0047] (2) Preparation of PtO-WO3 composite nanomaterials: The same as step (2) in Example 1, except that the amount of chloroplatinic acid solution used is 100 uL.

[0048] (3) Characterization of morphology and gas-sensing performance: The material obtained by high-temperature calcination in the previous step was subjected to SEM testing. The microscopic morphology was a rectangular block with small-sized dot-like substances visible on the surface. Under the working temperature of 250°C, the response value of the PtO-WO3 composite nanomaterial to 100ppm hydrogen was 215.

[0049] Comparative Example 1

[0050] A WO3 nano material and a preparation method thereof, comprising the following steps:

[0051] (1) Preparation of basic WO3 material: The same as step (1) in Example 1, except that the amount of HCl solution with a mass fraction of about 37% is 10 mL.

[0052] (2) Morphological characterization: The sample obtained by the hydrothermal method in the previous step was subjected to SEM test. Compared with the basic WO3 material in the embodiment, the surface of the sample in this comparative example was not smooth and more debris was visible, indicating that there were many incompletely developed WO3 materials, which was not conducive to further experiments.

[0053] Comparative Example 2

[0054] A WO3 nanomaterial and its preparation method and gas sensing application, comprising the following steps:

[0055] (1) Preparation of basic WO3 material: same as step (1) in Example 1.

[0056] (2) Preparation of WO3 nanomaterials: The same as step (2) in Example 1, except that the amount of chloroplatinic acid solution used is 0 uL.

[0057] (3) Characterization of morphology and gas-sensing performance: The material obtained by high-temperature calcination in the previous step was subjected to SEM testing. The microscopic morphology was a rectangular block, and no small-sized point-like substances were found on the surface. The sample prepared in the above method was coated on a gold interdigital electrode by a coating method to make a prototype device. The prepared gas-sensitive prototype device was further placed in a CGS-MT optoelectronic integrated test platform for gas-sensing performance testing. Under the working temperature of 200°C, the device's response value to 100ppm hydrogen was only about 1.

[0058] The above description is only a preferred embodiment of the present invention, which is used to help explain the present invention. The protection scope of the present invention is not limited to the above embodiment, and all technical solutions under the concept of the present invention belong to the protection scope of the present invention.

Claims

1. A PtO-WO 3 Preparation method of composite nanomaterials, It is characterized in that The method comprises preparing a basic WO by a hydrothermal method. 3 Nanocubes were further prepared by impregnation combined with calcination to obtain PtO-WO 3 Composite nanomaterials.

2. PtO-WO according to claim 1 3 Preparation method of composite nanomaterials, It is characterized in that The hydrothermal method prepared the basic WO 3 The nanocubes specifically include: selecting sodium tungstate dihydrate as a tungsten source, dissolving it in deionized water, adding hydrochloric acid, wherein the volume ratio of the hydrochloric acid to the deionized water is controlled to be 1:2-5:1, the hydrothermal reaction temperature is set to 140-200°C, and the hydrothermal time is 12-24h.

3. PtO-WO according to claim 1 3 Preparation method of composite nanomaterials, It is characterized in that The PtO-WO prepared by the impregnation method combined with the calcination treatment 3 Composite nanomaterials, specifically comprising: 3 The nanocube powder was mixed with chloroplatinic acid solution for impregnation, and the sample was further collected by centrifugation and dried before calcination to obtain PtO-WO 3 Composite nanomaterials.

4. PtO-WO according to claim 3 3 Preparation method of composite nanomaterials, It is characterized in that The WO 3 The amount of nanocube powder and chloroplatinic acid solution was calculated based on the ratio of PtO to WO. 3 The mass ratio ranges from 0.28 to 7.8%.

5. The PtO-WO according to claim 3 3 Preparation method of composite nanomaterials, It is characterized in that The impregnation operation is: 3 The nanocube powder is dispersed in deionized water, and chloroplatinic acid solution is dropped into the solution and kept at 80-100°C for 10-20 minutes.

6. The PtO-WO according to claim 3 3 Preparation method of composite nanomaterials, It is characterized in that The calcination treatment temperature is set at 300-400° C., the calcination time is 1-2 hours, and the heating rate is set at 1-2° C. / min.

7. A PtO-WO 3 Composite nanomaterials, It is characterized in that The method is prepared by the method according to any one of claims 1 to 6.

8. PtO-WO according to claim 7 3 Gas sensing applications of composite nanomaterials, It is characterized in that The material is used to realize efficient detection of hydrogen, the working temperature of the prototype gas sensor is 50 to 350° C., and the detection limit reaches the ppb level.

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