Palladium sulfide composite molybdenum disulfide hierarchical nanostructure based nitrogen dioxide sensor and preparation method thereof

Abstract

The invention provides a palladium sulfide composite molybdenum disulfide hierarchical nanostructure based nitrogen dioxide sensor and a preparation method thereof, and belongs to the technical field of sensors and composite nanomaterials. The sensor comprises a substrate and a gas sensitive layer loaded on the substrate, the gas sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial, PdS nanoparticle clusters in the palladium sulfide-molybdenum disulfide composite nanomaterial are embedded in the surface of MoS2 nanoflowers, and PdS and MoS2 form a heterojunction, so that the separation and transmission rate of current carriers is increased, and the performance of the gas sensor is improved. Therefore, the gas-sensitive performance of the nitrogen dioxide sensor is improved, and the nitrogen dioxide sensor has a high response value and fast response recovery time for NO2 with ppm-level concentration.

Description

Technical Field

[0001] The invention belongs to the field of sensor technology and composite nanomaterial technology, and in particular relates to a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor and a preparation method thereof. Background Art

[0002] Nitrogen dioxide (NO 2 NOx is a colorless gas that exists in daily life for a long time. It is also a toxic and harmful pollutant. It mainly comes from manufacturing production, vehicle emissions and fuel combustion. Its production cannot be completely curbed, and it poses a major threat to the environment and human body. Long-term exposure to high concentrations of NOx 2 It can irritate human respiratory tissue and eyes, and even cause irreversible damage to other important parts of the human body. When it comes into contact with other pollutants or water, it will react, leading to natural disasters such as smog and acid rain, causing inevitable damage to the living environment. Therefore, it is necessary to accurately and quickly detect NO 2 Concentration is very important. Develop NO detectors with fast response, high sensitivity and wide detection range. 2 Gas sensors are of great significance for protecting human health and monitoring the atmospheric environment.

[0003] Gas sensors based on metal oxide semiconductor materials have developed rapidly due to their low cost, low power consumption, simple manufacturing, high sensitivity and fast response. For semiconductor sensors, selecting materials that are sensitive to the target gas is a key step in preparing high-performance gas sensors. At present, many two-dimensional materials with excellent performance have been developed and applied to various fields. Studies have shown that two-dimensional transition metal chalcogenide (TMDs) nanomaterials are considered to be excellent sensing materials for room temperature gas sensors, which can reduce the detection limit of sensors. Among them, MoS 2 With excellent electrical properties and large specific surface area, it can provide more adsorption sites and improve the mobility of carriers. As a p-type TMD material, it has broad development prospects in the field of gas sensing. However, poor selectivity and slow response / recovery time are the limitations of single MoS 2 Gas sensors are one of the key issues in practical gas sensing applications. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor and a preparation method thereof.

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

[0006] One of the technical solutions of the present invention:

[0007] A palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, comprising a substrate and a gas-sensitive layer loaded on the substrate, wherein the gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial (PdS / MoS 2 composite nanomaterials).

[0008] Furthermore, the thickness of the gas-sensitive layer is 1-500 μm.

[0009] Furthermore, the palladium sulfide-molybdenum disulfide composite nanomaterial comprises palladium sulfide nanoparticles (PdS nanoparticles) and nanoflower-shaped molybdenum disulfide (nanoflower-shaped MoS 2 ).

[0010] Furthermore, the palladium sulfide-molybdenum disulfide composite nanomaterial is prepared by mixing palladium sulfide nanoparticles and nanoflowers in ethanol, and the mixing includes one of mechanical compounding, ultrasonic compounding and in-situ growth.

[0011] Furthermore, the palladium sulfide nanoparticles and nanoflowers are prepared by a hydrothermal method; more specifically, the hydrothermal method includes conventional hydrothermal or microwave hydrothermal; when the hydrothermal method is conventional hydrothermal, the temperature of the hydrothermal reaction is 120-250°C, and the time of the hydrothermal reaction is 5-30h; when the hydrothermal method is microwave hydrothermal, the microwave power is 100-800W.

[0012] Furthermore, the raw materials for preparing the palladium sulfide nanoparticles include palladium hydrochloride (H 2 PdCl 4 ) and thiourea (CH 4 N 2 S); the raw materials for preparing the nano flower-shaped nano flower include sodium molybdate (Na 2 MoO 4 ·2H 2 O) and thiourea (CH 4 N 2 S).

[0013] Furthermore, the substrate is a rigid substrate or a flexible substrate.

[0014] Furthermore, the rigid substrate is one of a silicon-based substrate, a zirconium oxide substrate and an aluminum oxide substrate; the flexible substrate is one of a polyimide (PI) substrate, a polyethylene terephthalate (PET) substrate, a polyurethane (PU) substrate and a paper-based substrate.

[0015] The second technical solution of the present invention:

[0016] A method for preparing a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor comprises the following steps:

[0017] The substrate is pretreated, and the palladium sulfide-molybdenum disulfide composite nanomaterial is coated on the substrate, and after drying, the palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor is obtained.

[0018] Furthermore, the coating method includes one of screen printing, drip coating, spray coating, spin coating and inkjet printing.

[0019] Furthermore, the substrate pretreatment process includes cleaning and drying steps; specifically, the substrate is ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60-80° C. for 6-12 hours.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] The invention discloses a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor for NO 2 The gas sensitive material is a palladium sulfide-molybdenum disulfide composite nanomaterial, in which PdS nanoparticle clusters are embedded in MoS 2 The surface of nanoflowers, PdS and MoS 2 The formation of a heterojunction improves the separation and transmission rate of carriers, thereby improving the gas-sensing performance of the nitrogen dioxide sensor, making the nitrogen dioxide sensor sensitive to NO at ppm level concentrations. 2 It has a higher response value and a faster response recovery time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 This is a scanning electron microscope image of the palladium sulfide-molybdenum disulfide composite nanomaterial prepared in Example 1;

[0024] Figure 2 The PdS / MoS prepared in Example 1 2 Composite nanomaterial-based NO 2 Gas sensor for 50-10ppm NO at room temperature 2 Real-time resistance change curve;

[0025] Figure 3 The PdS / MoS prepared in Example 1 2 Composite nanomaterial-based NO 2 Gas sensor at room temperature for 50ppmNO 2 Repeatability curve. DETAILED DESCRIPTION

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0028] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0029] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0030] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0031] The present invention provides a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, comprising a substrate and a gas-sensitive layer loaded on the substrate, wherein the gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial (PdS / MoS 2 composite nanomaterials).

[0032] The thickness of the gas-sensitive layer directly affects the surface area of ​​the sensor in contact with the gas. A thinner gas-sensitive layer may provide a larger effective sensitive interface, thereby increasing the contact opportunities between gas molecules and the sensor surface and improving the adsorption and reaction efficiency of the gas. However, if the gas-sensitive layer is too thin, it may cause the sensor's response to the gas to be unstable or the sensitivity to be reduced. A thicker gas-sensitive layer may limit the diffusion of gas molecules into the interior of the sensor, thereby affecting the response speed and recovery time. The thickness of the gas-sensitive layer is optimized according to the heterogeneous structure formed by the composition of the gas-sensitive layer, and matched with the thickness of the electron depletion layer to improve the gas-sensitive performance of the sensor. Based on this, in a preferred embodiment of the present invention, the thickness of the gas-sensitive layer is 1-500μm.

[0033] When palladium sulfide nanoparticles and molybdenum disulfide nanoparticles are combined to form a heterostructure, due to their different work functions, electrons will transfer from the material with a lower work function to the material with a higher work function until the Fermi levels of the two materials are equal. This electron transfer will lead to the formation of an electron depletion layer or an electron accumulation layer at the interface of the heterostructure, thereby affecting the conductivity and gas sensing performance of the sensor. The formation of a heterostructure can increase the number of active sites at the interface, and the increased active sites can promote more NO 2 The molecules participate in the reaction, resulting in a greater resistance change, thereby improving the response of the sensor. The amount of palladium sulfide nanoparticles and molybdenum disulfide nanoparticles used will affect the density of active sites in the heterostructure, thereby affecting the adsorption capacity and reaction rate of gas molecules. Based on this, in a preferred embodiment of the present invention, the palladium sulfide-molybdenum disulfide composite nanomaterial includes palladium sulfide nanoparticles (PdS nanoparticles) and nanoflower-shaped molybdenum disulfide (nanoflower-shaped MoS) in a mass ratio of 1: (0.5-5). 2 ).

[0034] In a preferred embodiment of the present invention, the palladium sulfide-molybdenum disulfide composite nanomaterial is prepared by mixing palladium sulfide nanoparticles and nano-flower-shaped molybdenum disulfide in ethanol, and the mixing includes one of mechanical compounding, ultrasonic compounding and in-situ growth. Among them, mechanical compounding refers to the process of uniformly mixing palladium sulfide nanoparticles and molybdenum disulfide nanoparticles by mechanical stirring (such as paddle stirring, turbine stirring, magnetic stirring, etc.); ultrasonic compounding refers to the process of uniformly mixing palladium sulfide nanoparticles and molybdenum disulfide nanoparticles under ultrasonic treatment conditions; in-situ growth refers to the process of uniformly mixing nano-flower-shaped MoS prepared by hydrothermal method. 2 , PdS nanoparticles as raw materials, and then grow palladium sulfide nanoparticles on the surface of nanoflower-like molybdenum disulfide by hydrothermal method. The morphology of PdS nanoparticles prepared by hydrothermal method is nanoparticle clusters. 2 PdS nanoparticles are dispersed in ethanol, and the PdS nanoparticle clusters are embedded in MoS 2 The surface of nanoflowers.

[0035] In a preferred embodiment of the present invention, the palladium sulfide nanoparticles and nanoflower-shaped molybdenum disulfide are both prepared by a hydrothermal method; more specifically, the hydrothermal method includes conventional hydrothermal or microwave hydrothermal; when the hydrothermal method is conventional hydrothermal, the temperature of the hydrothermal reaction is 120-250°C, and the time of the hydrothermal reaction is 5-30h; when the hydrothermal method is microwave hydrothermal, the microwave power is 100-800W.

[0036] In a preferred embodiment of the present invention, the raw materials for preparing the palladium sulfide nanoparticles include palladium hydrochloride (H 2 PdCl 4 ) and thiourea (CH 4 N 2 S), the raw materials for preparing the nano flower-shaped molybdenum disulfide include sodium molybdate (Na 2 MoO 4 ·2H 2 O) and thiourea (CH 4 N 2 S).

[0037] Exemplarily, in the embodiment of the present invention, the preparation method of the palladium sulfide nanoparticles (PdS nanoparticles) used is:

[0038] 0.75 mmol H 2 PdCl 4 , add 1 g of thiourea to a reaction container containing 80 mL of deionized water, stir magnetically for 30 min until fully dissolved, transfer to a polytetrafluoroethylene-lined high-pressure reactor, maintain at 120-250°C for 5-30 h, take out after cooling, collect the final product by centrifugation at 8000 rpm, wash it with ethanol and deionized water for 3 times respectively, and dry it in a drying oven at 60°C for 10 h to obtain PdS nanoparticles.

[0039] For example, in the present embodiment, the nanoflower-shaped molybdenum disulfide (nanoflower-shaped molybdenum disulfide MoS 2 ) is prepared by:

[0040] 5mmol of Na 2 MoO 4 ·2H 2 O and 5 mmol thiourea were added to a reaction vessel containing 50 mL deionized water, and magnetic stirring was performed for 30 min until the mixture was completely dissolved. The pH of the mixed solution was adjusted to 3 using a hydrochloric acid solution, and then the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and kept at 120-250 °C for 5-30 h. After cooling, the mixture was taken out and the final product was collected by centrifugation at 6000 rpm, and washed with ethanol and deionized water for 3 times respectively. After being dried in a drying oven at 60 °C for 12 h, the nanoflower-like molybdenum disulfide MoS 2 .

[0041] In a preferred embodiment of the present invention, the substrate is a rigid substrate or a flexible substrate, more specifically, the rigid substrate is one of a silicon-based substrate, a zirconium oxide substrate and an aluminum oxide substrate; the flexible substrate is one of a polyimide (PI) substrate, a polyethylene terephthalate (PET) substrate, a polyurethane (PU) substrate and a paper-based substrate.

[0042] The embodiment of the present invention also provides a method for preparing the palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, comprising the following steps:

[0043] The substrate is pretreated, and the palladium sulfide-molybdenum disulfide composite nanomaterial is coated on the substrate, and after drying, the palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor is obtained.

[0044] In a preferred embodiment of the present invention, the coating method comprises one of screen printing, drip coating, spray coating, spin coating and inkjet printing.

[0045] In a preferred embodiment of the present invention, the substrate pretreatment process includes cleaning and drying steps; specifically, the substrate is ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60-80° C. for 6-12 hours.

[0046] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in the art and are not the focus of the present invention.

[0047] The room temperature in the embodiment of the present invention refers to 25±2°C.

[0048] The raw materials used in the embodiments of the present invention are all commercially available.

[0049] The technical solution of the present invention is further illustrated by the following embodiments.

[0050] Example 1

[0051] This embodiment proposes a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, including a sensor substrate and a gas-sensitive layer, wherein the substrate adopts an aluminum oxide-based platinum interdigitated electrode, the gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial, and the thickness of the gas-sensitive layer is 1 μm.

[0052] The preparation method of the palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor specifically comprises the following steps:

[0053] (1) Substrate pretreatment

[0054] The aluminum oxide-based platinum interdigital electrode was ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60°C for 8 h for later use;

[0055] (2) Preparation of PdS nanoparticle materials

[0056] 0.75 mmol H 2 PdCl 4 1 g of thiourea was added to a reaction vessel containing 80 mL of deionized water, and magnetically stirred for 30 min until fully dissolved, and then transferred to a polytetrafluoroethylene-lined autoclave, and kept at 160°C for 12 h. After cooling, the final product was collected by centrifugation at 8000 rpm, and washed with ethanol and deionized water for 3 times respectively, and dried in a drying oven at 60°C for 10 h to obtain PdS nanoparticles;

[0057] (3) Preparation of nanoflower-like MoS 2

[0058] 5mmol of Na 2 MoO 4 ·2H 2 O and 5 mmol thiourea were added to a reaction vessel containing 50 mL deionized water, and magnetic stirring was performed for 30 min until the mixture was completely dissolved. The pH of the mixed solution was adjusted to 3 with hydrochloric acid solution, and then the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and kept at 210 °C for 24 h. After cooling, the final product was collected by centrifugation at 6000 rpm, and washed with ethanol and deionized water for 3 times respectively, and dried in a drying oven at 60 °C for 12 h to obtain nanoflower-like MoS 2 ;

[0059] (4) Preparation of palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor

[0060] Weigh the nanoflower-like MoS with a mass ratio of 1:1 2 5 mg of PdS nanoparticles were mixed with 1 mL of ethanol and ultrasonically treated for 10 min to obtain palladium sulfide-molybdenum disulfide composite nanomaterials. The palladium sulfide-molybdenum disulfide composite nanomaterials were then coated on the pretreated aluminum oxide-based platinum interdigitated electrode by screen printing to obtain a gas sensitive layer. After drying, a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor (PdS / MoS 2 Composite nanomaterial membrane-based NO 2 gas sensor).

[0061] Example 2

[0062] This embodiment proposes a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, including a sensor substrate and a gas-sensitive layer, wherein the substrate adopts a zirconium oxide-based platinum interdigital electrode, the gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial, and the thickness of the gas-sensitive layer is 10 μm. The preparation method specifically includes the following steps:

[0063] (1) Substrate pretreatment

[0064] The zirconium oxide-based platinum interdigital electrode was ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60°C for 8 h for later use;

[0065] (2) Preparation of PdS nanoparticle materials

[0066] 0.75 mmol H 2 PdCl 4 1 g of thiourea was added to a reaction vessel containing 80 mL of deionized water, and magnetically stirred for 30 min until fully dissolved, and then transferred to a polytetrafluoroethylene-lined autoclave, and kept at 140°C for 15 h. After cooling, the final product was collected by centrifugation at 8000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60°C for 10 h to obtain PdS nanoparticles;

[0067] (3) Preparation of nanoflower-like MoS 2

[0068] 5mmol of Na 2 MoO 4 ·2H 2 O and 5 mmol thiourea were added to a reaction vessel containing 50 mL deionized water, and magnetic stirring was performed for 30 min until the mixture was completely dissolved. The pH of the mixed solution was adjusted to 3 using hydrochloric acid solution, and then the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and kept at 210 °C for 30 h. After cooling, the final product was collected by centrifugation at 6000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60 °C for 12 h to obtain nanoflower-like MoS 2 ;

[0069] (4) Preparation of palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor

[0070] Weigh the nanoflower-like MoS with a mass ratio of 1:2 2 The mixture was mixed with 10 mg of PdS nanoparticles and then ultrasonicated for 10 min to obtain a palladium sulfide-molybdenum disulfide composite nanomaterial. The palladium sulfide-molybdenum disulfide composite nanomaterial was then coated on the pretreated substrate by a drop coating process to obtain a gas sensitive layer. After drying, a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor (PdS / MoS 2 Composite nanomaterial membrane-based NO 2 gas sensor).

[0071] Example 3

[0072] This embodiment proposes a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, including a sensor substrate and a gas-sensitive layer, wherein the substrate uses a polyimide-based platinum interdigitated electrode, the gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial, and the thickness of the gas-sensitive layer is 10 μm. The preparation method specifically includes the following steps:

[0073] (1) Substrate pretreatment

[0074] The polyimide-based platinum interdigitated electrode was ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60°C for 8 h for later use;

[0075] (2) Preparation of PdS nanoparticle materials

[0076] 0.75 mmol H 2 PdCl 4 1 g of thiourea was added to a reaction vessel containing 80 mL of deionized water, and magnetically stirred for 30 min until fully dissolved, and then transferred to a polytetrafluoroethylene-lined autoclave, and kept at 180°C for 10 h. After cooling, the final product was collected by centrifugation at 8000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60°C for 10 h to obtain PdS nanoparticles;

[0077] (3) Preparation of nanoflower-like MoS 2

[0078] 5mmol of Na 2 MoO 4 ·2H 2 O and 5 mmol thiourea were added to a reaction vessel containing 50 mL deionized water, and magnetic stirring was performed for 30 min until the mixture was completely dissolved. The pH of the mixed solution was adjusted to 3 using hydrochloric acid solution, and then the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and kept at 230 °C for 20 h. After cooling, the final product was collected by centrifugation at 6000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60 °C for 12 h to obtain nanoflower-like MoS 2 ;

[0079] (4) Preparation of palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor

[0080] Weigh nanoflower-like MoS with a mass ratio of 1:0.5 2 The mixture was mixed with 10 mg of PdS nanoparticles and then ultrasonicated to obtain a palladium sulfide-molybdenum disulfide composite nanomaterial. The palladium sulfide-molybdenum disulfide composite nanomaterial was then coated on a pretreated substrate by spin coating to obtain a gas-sensitive layer. After drying, a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor (PdS / MoS 2Composite nanomaterial membrane-based NO 2 gas sensor).

[0081] Example 4

[0082] This embodiment proposes a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, including a sensor substrate and a gas-sensitive layer, wherein the substrate adopts a polyurethane-based platinum interdigital electrode, the gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial, and the thickness of the gas-sensitive layer is 500 μm. The preparation method specifically includes the following steps:

[0083] (1) Substrate pretreatment

[0084] The aluminum oxide-based platinum interdigital electrode was ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 80°C for 6 hours for later use;

[0085] (2) Preparation of PdS nanoparticle materials

[0086] 0.75 mmol H 2 PdCl 4 1 g of thiourea was added to a reaction vessel containing 80 mL of deionized water, and magnetically stirred for 30 min until fully dissolved, and then transferred to a polytetrafluoroethylene-lined autoclave, and kept at 250°C for 5 h. After cooling, the final product was collected by centrifugation at 8000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60°C for 10 h to obtain PdS nanoparticles;

[0087] (3) Preparation of nanoflower-like MoS 2

[0088] 5mmol of Na 2 MoO 4 ·2H 2 O and 5 mmol thiourea were added to a reaction vessel containing 50 mL deionized water, and magnetic stirring was performed for 30 min until the mixture was completely dissolved. The pH of the mixed solution was adjusted to 3 using hydrochloric acid solution, and then the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and kept at 250 °C for 5 h. After cooling, the final product was collected by centrifugation at 6000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60 °C for 12 h to obtain nanoflower-like MoS 2 ;

[0089] (4) Preparation of palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor

[0090] Weigh the nanoflower-like MoS with a mass ratio of 1:5 2A total of 50 mg of PdS nanoparticles were mixed with 1 mL of ethanol and ultrasonically treated to obtain a palladium sulfide-molybdenum disulfide composite nanomaterial. The palladium sulfide-molybdenum disulfide composite nanomaterial was then coated on a pretreated substrate by spin coating and inkjet printing to obtain a gas-sensitive layer. After drying, a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor (PdS / MoS 2 Composite nanomaterial membrane-based NO 2 gas sensor).

[0091] Example 5

[0092] This embodiment proposes a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, including a sensor substrate and a gas-sensitive layer, wherein the substrate adopts a polyethylene terephthalate-based platinum interdigitated electrode, the gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial, and the thickness of the gas-sensitive layer is 300 μm. The preparation method specifically includes the following steps:

[0093] (1) Substrate pretreatment

[0094] The aluminum oxide-based platinum interdigital electrode was ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60°C for 12 h for later use;

[0095] (2) Preparation of PdS nanoparticle materials

[0096] 0.75 mmol H 2 PdCl 4 1 g of thiourea was added to a reaction vessel containing 80 mL of deionized water, and magnetically stirred for 30 min until fully dissolved, and then transferred to a polytetrafluoroethylene-lined autoclave, and kept at 120°C for 30 h. After cooling, the final product was collected by centrifugation at 8000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60°C for 10 h to obtain PdS nanoparticles;

[0097] (3) Preparation of nanoflower-like MoS 2

[0098] 5mmol of Na 2 MoO 4 ·2H 2 O and 5 mmol thiourea were added to a reaction vessel containing 50 mL deionized water, and magnetic stirring was performed for 30 min until the mixture was completely dissolved. The pH of the mixed solution was adjusted to 3 using hydrochloric acid solution, and then the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and kept at 120 °C for 30 h. After cooling, the final product was collected by centrifugation at 6000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60 °C for 12 h to obtain nanoflower-like MoS 2 ;

[0099] (4) Preparation of palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor

[0100] Weigh nanoflower-like MoS with a mass ratio of 1:0.5 2 A total of 30 mg of PdS nanoparticles were mixed with 1 mL of ethanol and ultrasonically treated to obtain a palladium sulfide-molybdenum disulfide composite nanomaterial. The palladium sulfide-molybdenum disulfide composite nanomaterial was then coated on a pretreated substrate using an inkjet printing process to obtain a gas-sensitive layer. After drying, a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor (PdS / MoS 2 Composite nanomaterial membrane-based NO 2 gas sensor).

[0101] Example 6

[0102] This embodiment proposes a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, including a sensor substrate and a gas-sensitive layer, wherein the substrate adopts a silicon-based platinum interdigital electrode, the gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial, and the thickness of the gas-sensitive layer is 300 μm. The preparation method specifically includes the following steps:

[0103] (1) Substrate pretreatment

[0104] The aluminum oxide-based platinum interdigital electrode was ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60°C for 12 h for later use;

[0105] (2) Preparation of PdS nanoparticles

[0106] 0.75mmol chloropalladic acid and 1g thiourea were added to a reaction container containing 80mL deionized water, and magnetically stirred for 30min until fully dissolved. Then, the power was controlled to 200W in a microwave hydrothermal synthesizer, and the temperature was kept at 160°C for 1h. After cooling, the final product was collected by centrifugation at 8000rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60°C to obtain PdS nanoparticle material.

[0107] (3) Preparation of nanoflower-like MoS 2

[0108] 5mmol of Na 2 MoO 4 ·2H 2O and 5 mmol thiourea were added to a reaction container containing 50 mL deionized water, and magnetic stirring was performed for 30 min until the mixture was completely dissolved. The pH of the mixed solution was adjusted to 3 using a hydrochloric acid solution. The power was controlled to 200 W in a microwave hydrothermal synthesizer, and the mixture was kept at 210 °C for 2 h. After cooling, the final product was collected by centrifugation at 6000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60 °C for 12 h to obtain nanoflower-like MoS 2 ;

[0109] (4) Preparation of palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor

[0110] Weigh nanoflower-like MoS with a mass ratio of 1:0.5 2 A total of 30 mg of PdS nanoparticles were mixed with 1 mL of ethanol and ultrasonically treated to obtain a palladium sulfide-molybdenum disulfide composite nanomaterial. The palladium sulfide-molybdenum disulfide composite nanomaterial was then coated on a pretreated substrate by a spin coating process to obtain a gas-sensitive layer. After drying, a palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor (PdS / MoS 2 Composite nanomaterial membrane-based NO 2 gas sensor).

[0111] Comparative Example 1

[0112] Same as Example 1, except that the thickness of the gas sensitive layer is 0.1 μm.

[0113] Comparative Example 2

[0114] Same as Example 1, except that the thickness of the gas sensitive layer is 800 μm.

[0115] Comparative Example 3

[0116] The same as Example 1, except that the flower-shaped MoS with a mass ratio of 1:10 is weighed. 2 Nanoparticles and PdS nanoparticles.

[0117] Comparative Example 4

[0118] The same as Example 1, the only difference is that the gas sensitive layer is made of molybdenum disulfide nanomaterial, specifically:

[0119] This comparative example proposes a molybdenum disulfide nanostructure-based nitrogen dioxide sensor, including a sensor substrate and a gas-sensitive layer, wherein the substrate adopts an aluminum oxide-based platinum interdigital electrode, and the thickness of the gas-sensitive layer is 1 μm. The preparation method specifically includes the following steps:

[0120] (1) Substrate pretreatment

[0121] The aluminum oxide-based platinum interdigital electrode was ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60°C for 8 hours for later use;

[0122] (2) Preparation of nanoflower-like MoS 2

[0123] 5mmol of Na 2 MoO 4 ·2H 2 O and 5 mmol thiourea were added to a reaction vessel containing 50 mL deionized water, and magnetic stirring was performed for 30 min until the mixture was completely dissolved. The pH of the mixed solution was adjusted to 3 using hydrochloric acid solution, and then the mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave and kept at 210 °C for 24 h. After cooling, the final product was collected by centrifugation at 6000 rpm, and washed with ethanol and deionized water for 3 times respectively, and then dried in a drying oven at 60 °C for 12 h to obtain nanoflower-like MoS 2 ;

[0124] (3) Preparation of MoS2 nanostructure-based nitrogen dioxide sensor

[0125] Weigh 5 mg of nanoflower-like MoS 2 , and then mixed with 1 mL of ethanol and ultrasonically treated to obtain molybdenum disulfide nanomaterials, and then the molybdenum disulfide nanomaterials were coated on the pretreated substrate by screen printing to obtain a gas-sensitive layer, and after drying, a molybdenum disulfide nanostructure-based nitrogen dioxide sensor (MoS 2 Nanomaterial membrane-based NO 2 gas sensor).

[0126] Comparative Example 5

[0127] The same as Example 1, the only difference is that the gas sensitive layer is palladium sulfide nanomaterial, specifically:

[0128] This comparative example proposes a palladium sulfide nanostructure-based nitrogen dioxide sensor, including a sensor substrate and a gas-sensitive layer, wherein the substrate adopts an aluminum oxide-based platinum interdigital electrode, and the thickness of the gas-sensitive layer is 1 μm. The preparation method specifically includes the following steps:

[0129] (1) Substrate pretreatment

[0130] The aluminum oxide-based platinum interdigital electrode was ultrasonically cleaned with acetone, alcohol, and deionized water in sequence, and then dried at 60°C for 8 hours for later use;

[0131] (2) Preparation of PdS nanoparticles

[0132] 0.75 mmol H 2 PdCl 41 g of thiourea was added to a reaction vessel containing 80 mL of deionized water, and magnetically stirred for 30 min until fully dissolved, and then transferred to a polytetrafluoroethylene-lined autoclave, and kept at 160°C for 12 h. After cooling, the final product was collected by centrifugation at 8000 rpm, and washed with ethanol and deionized water for 3 times respectively, and dried in a drying oven at 60°C for 10 h to obtain PdS nanoparticles;

[0133] (3) Preparation of palladium sulfide nanostructure-based nitrogen dioxide sensor

[0134] 5 mg of PdS nanoparticles were weighed and mixed with 1 mL of ethanol and ultrasonically treated to obtain palladium sulfide nanomaterials. The palladium sulfide nanomaterials were then coated on the pretreated substrate using a screen printing process to obtain a gas-sensitive layer. After drying, a palladium sulfide nanostructure-based nitrogen dioxide sensor (PdS nanomaterial film-based NO 2 gas sensor).

[0135] Performance Testing

[0136] The scanning electron microscope image of the palladium sulfide-molybdenum disulfide composite nanomaterial prepared in Example 1 is shown in Figure 1 It can be seen that the PdS nanoparticle clusters are embedded in the MoS 2 The surface of nanoflowers.

[0137] The performance test of the nitrogen dioxide sensors prepared in Examples 1-6 and Comparative Examples 1-5 of the present invention was carried out according to the method disclosed in the art, and the resistance signal of the sensors prepared above was tested using a Keithley 2700 data acquisition device. The specific steps are:

[0138] (1) Connect the sensor to the gas-sensitive test equipment, let air flow into the equipment until it stabilizes, and record the resistance value R of the device in the air. a ; (2) Introduce NO into the device 2 Until the resistance value reaches stability again, record the device in NO 2 The resistance value R g (3) Air is introduced into the device again until the resistance becomes stable and the device completes a response recovery process.

[0139] Response value = (R a -R g ) / R a × 100%, where R a is the output resistance value of the sensor in air atmosphere, R g NO 2 Sensor output resistance value under atmosphere.

[0140] Different NO 2The concentration was obtained by gas dilution method, and the test concentration was 0-50 ppm.

[0141] PdS / MoS prepared in Example 1 2 Composite nanomaterial membrane-based NO 2 Gas sensor for 50-10ppm NO at room temperature 2 The real-time resistance change curve is shown in Figure 2 , it can be seen that NO 2 After the NO 2 The concentration increases and decreases. For 50ppmNO 2 The gas showed a response value of 46.4% and a response / recovery time of 42 / 52s.

[0142] Under the same test method, the gas sensor prepared in Example 2 was tested for 50ppm NO 2 Gas showed a response value of 45.3% and a response / recovery time of 40 / 52s;

[0143] The gas sensor prepared in Example 3 is sensitive to 50 ppm NO 2 Gas showed a response value of 44.6% and a response / recovery time of 45 / 58s;

[0144] The gas sensor prepared in Example 4 is sensitive to 50 ppm NO 2 The gas showed a response value of 47.1% with a response / recovery time of 50 / 61 s.

[0145] The gas sensor prepared in Example 5 is sensitive to 50 ppm NO 2 The gas showed a response value of 46.5% with a response / recovery time of 48 / 59s.

[0146] The gas sensor prepared in Example 6 is sensitive to 50 ppm NO 2 The gas showed a response value of 45.8%, and the response / recovery time was 51 / 66 s. It can be seen that the performances of the gas sensors prepared in Examples 1-6 are relatively similar.

[0147] The gas sensor prepared in Comparative Example 1 was sensitive to 50 ppm NO 2 The gas showed a response value of 2.4% and a response / recovery time of 91 / 124s;

[0148] The gas sensor prepared in Comparative Example 2 was sensitive to 50 ppm NO 2 The gas showed a response value of 12.1% and a response / recovery time of 187 / 196s;

[0149] The gas sensor prepared in Comparative Example 3 was 2The gas showed a response value of 10.3% and a response / recovery time of 120 / 121s;

[0150] The gas sensor prepared in Comparative Example 4 was tested for 50 ppm NO 2 The gas showed a response value of 8.1% with a response / recovery time of 187 / 196s.

[0151] The gas sensor prepared in Comparative Example 5 was sensitive to 50 ppm NO 2 The gas showed a response value of 19.3% with a response / recovery time of 122 / 129s.

[0152] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor, comprising a substrate and a gas-sensitive layer loaded on the substrate, characterized in that: The gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nano material.

2. The palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor according to claim 1, characterized in that: The thickness of the gas sensitive layer is 1-500 μm.

3. The palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor according to claim 1, characterized in that: The palladium sulfide-molybdenum disulfide composite nanomaterial comprises palladium sulfide nanoparticles and molybdenum disulfide nanoparticles in a mass ratio of 1: (0.5-5).

4. The palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor according to claim 3, characterized in that: The palladium sulfide-molybdenum disulfide composite nanomaterial is prepared by mixing palladium sulfide nanoparticles and nano-flower-shaped molybdenum disulfide in ethanol; The mixed preparation method is mechanical compounding, ultrasonic compounding or in-situ growth.

5. The palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor according to claim 3, characterized in that: The palladium sulfide nanoparticles and nano-flower-shaped molybdenum disulfide are both prepared by a hydrothermal method.

6. The palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor according to claim 5, characterized in that: The hydrothermal method is conventional hydrothermal or microwave hydrothermal.

7. The palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor according to claim 1, characterized in that: The substrate is a rigid substrate or a flexible substrate.

8. A method for preparing a nitrogen dioxide sensor based on a palladium sulfide composite molybdenum disulfide hierarchical nanostructure according to any one of claims 1 to 7, characterized in that: The following steps are involved: The substrate is pretreated, and the palladium sulfide-molybdenum disulfide composite nanomaterial is coated on the substrate, and after drying, the palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor is obtained.

9. The method for preparing the palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor according to claim 8, characterized in that: The coating method includes one of screen printing, drop coating, spray coating, spin coating and inkjet printing.

10. The method for preparing the palladium sulfide composite molybdenum disulfide hierarchical nanostructure-based nitrogen dioxide sensor according to claim 8, characterized in that: The substrate pretreatment process includes cleaning and drying steps.

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