Hydrogen detection sensor and preparation method thereof

Abstract

The invention relates to a hydrogen detection sensor and a preparation method thereof. The hydrogen detection sensor comprises a base material, a color developing layer and a nano modification layer, wherein the color developing layer comprises PdO, and the nanometer modification layer comprises nanometer Au and nanometer Pd. According to the hydrogen detection sensor, the PdO developing layer is modified by nano Pd and nano Au together, so that hydrogen in air can be more effectively enriched, high-sensitivity detection of low-concentration hydrogen is realized, the reaction speed of hydrogen and PdO can be effectively increased, and the hydrogen detection sensor has higher response speed.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a hydrogen detection sensor and a preparation method thereof. Background Art

[0002] In recent years, color-changing hydrogen detection sensors based on PdO have attracted widespread attention. PdO can be reduced to Pd by hydrogen, changing from brown to black, and can therefore be used for hydrogen detection.

[0003] However, the traditional PdO-based hydrogen detection sensor must be in N2 or inert gas atmosphere to have good sensitivity and response speed. When air is used as the test environment, PdO will be obviously deactivated and the hydrogen detection sensor will respond slowly. Summary of the invention

[0004] Based on this, it is necessary to provide a hydrogen detection sensor and a preparation method thereof that can quickly respond to low concentration hydrogen in an air atmosphere and is easy to distinguish color changes.

[0005] In a first aspect of the present application, a hydrogen detection sensor is provided, comprising a substrate, a color-developing layer and a nano-modification layer, wherein the color-developing layer is located on the surface of the substrate, and the nano-modification layer is located on the surface of the color-developing layer away from the substrate; the material of the color-developing layer comprises PdO, and the material of the nano-modification layer comprises nano-Au and nano-Pd.

[0006] In some embodiments, in the nano-modified layer, the atomic ratio of Au to Pd is 1:1 to 1:4.

[0007] In some embodiments, the substrate comprises a flexible substrate.

[0008] In some embodiments, the material of the flexible substrate includes silicone rubber.

[0009] In some embodiments, a protective layer is further included, and the protective layer is located on a surface of the nano-modification layer away from the color development layer, and the material of the protective layer includes PMMA.

[0010] In some embodiments, the thickness of the nano-modified layer is 3 nm to 10 nm.

[0011] In some embodiments, the color development layer has a thickness of 30 nm to 60 nm.

[0012] In a second aspect of the present application, a method for preparing the hydrogen detection sensor provided in the first aspect of the present application is provided, comprising the following steps:

[0013] The color development layer is deposited on the surface of the substrate, and the nano-modification layer is deposited on the surface of the color development layer away from the substrate.

[0014] In some embodiments, the method further comprises: coating a protective layer material including PMMA on a surface of the nano-modified layer away from the color development layer, and drying the surface to form a protective layer on the surface of the nano-modified layer away from the color development layer.

[0015] In some embodiments, before depositing the color development layer on the surface of the substrate, the method further comprises: coating a substrate raw material on the surface of the substrate, and drying to obtain the substrate;

[0016] After forming the protective layer, the method further includes: separating the base material from the substrate.

[0017] The above hydrogen detection sensor modifies the PdO color development layer by nano-Pd and nano-Au, which can not only more effectively enrich the hydrogen in the air and realize the detection of low-concentration hydrogen in the air atmosphere, but also effectively improve the reaction speed of hydrogen and PdO, so that the hydrogen detection sensor has a faster response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0019] Figure 1 This is a structural diagram of a hydrogen detection sensor in one embodiment of the present application;

[0020] Figure 2 This is a flow chart of the preparation of a hydrogen detection sensor in one embodiment of the present application.

[0021] Description of reference numerals:

[0022] 100, substrate; 200, color development layer; 300, nano-modification layer; 400, protective layer. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0024] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In this application, "at least one" means more than one, such as one, two and more than two. "Multiple" or "several" means at least two, such as two, three, etc.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0026] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0027] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0028] In this application, "above" or "below" includes the number itself. For example, "1 below" includes 1.

[0029] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0030] Hydrogen is a flammable and explosive gas that can cause an explosion when its concentration reaches 4% to 75%. Therefore, it is necessary to detect the storage of hydrogen to prevent fires and explosions caused by hydrogen leakage. Hydrogen leaks need to be detected in scenarios such as hydrogen transportation, storage, and application. Traditional electric hydrogen detection sensors are difficult to accurately warn of hydrogen leaks in complex environments. Not only is the power supply problem difficult to solve, but there are certain safety risks in hydrogen leak detection when working with power. In addition, this type of sensor is expensive and complex in structure, and is not suitable for simple detection of hydrogen leaks in daily life.

[0031] At present, hydrogen detection sensors based on PdO color change have the advantages of low cost and passive operation. When in use, the sensing process of the hydrogen detection sensor mainly involves the reduction of active PdO to Pd in ​​hydrogen. The brown-yellow PdO will be reduced to black Pd by hydrogen, thereby indicating hydrogen leakage. In addition, since the ratio of reacting PdO and Pd depends on the hydrogen concentration, the hydrogen concentration in the environment can be judged by measuring the color difference of the color-developing layer.

[0032] The specific reaction pathway of hydrogen reduction of PdO is as follows:

[0033] Reaction 1: H2 dissociates on the PdO surface to produce H atoms;

[0034] Reaction 2: H atoms combine with PdO to form PdO-H;

[0035] Reaction 3: H atoms further combine with PdO-H to obtain Pd and H2O.

[0036] Compared with reaction 1 and reaction 2, reaction 3 is a fast reaction process. Since the color change of the hydrogen detection sensor occurs during reaction 3, when pure PdO is used for hydrogen color change detection, there may be a long introduction period and a slow response speed. When in an air atmosphere, especially at low hydrogen concentrations, the color change phenomenon responds slowly and the color change is not obvious, making it difficult to meet the requirements of highly sensitive, fast and easy-to-confirm hydrogen detection.

[0037] The present application provides a hydrogen detection sensor, which can maintain a good response effect for low-concentration hydrogen detection in an air atmosphere. In order to more clearly illustrate the structure of the hydrogen detection sensor, the hydrogen detection sensor will be introduced in conjunction with the accompanying drawings.

[0038] For example, see Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a hydrogen detection sensor provided in one embodiment of the present application.

[0039] One embodiment of the present application relates to a hydrogen detection sensor. The hydrogen detection sensor includes a substrate 100, a color layer 200, and a nano-modification layer 300. The color layer 200 is located on the surface of the substrate 100, and the nano-modification layer 300 is located on the surface of the color layer 200 away from the substrate 100. The material of the color layer 200 includes PdO, and the material of the nano-modification layer 300 includes nano-Au and nano-Pd.

[0040] The hydrogen detection sensor of the present application uses nano-modified particles including nano-Au and nano-Pd to modify the color development layer. The promoting effect of Pd on the hydrogen detection sensor of PdO can be reflected from two aspects. On the one hand, after the introduction of Pd, the reaction rate of the hydrogen detection sensor showed a significant improvement. Considering that the reaction rate of reaction 3 is relatively fast, the introduction of Pd may effectively increase the reaction rates of reaction 1 and reaction 2. After testing, when Pd is modified on the surface of PdO, the activation energy of hydrogen dissociation on the surface of PdO is reduced from 0.38eV to 0.12eV. At the same time, Pd also reduces the energy barrier for hydrogen diffusion and water formation, showing excellent catalytic performance. On the other hand, after the introduction of Pd, the color change phenomenon of the hydrogen detection sensor is more significant. Pd can adsorb and store hydrogen or H atomic source. After Pd is modified on the surface of PdO, it helps to enrich hydrogen in the air. Subsequently, active H can migrate across the Pd / PdO interface to reduce PdO, so that PdO obtains a higher degree of reduction, and therefore can show a more obvious color difference change.

[0041] The use of nano-Pd can effectively improve the sensing performance of PdO, but its response value and response speed are still difficult to meet the requirements of actual hydrogen leak detection under low concentration of hydrogen. In addition, pure Pd will gradually lose its catalytic properties in the reaction with hydrogen, which seriously affects the sensing performance.

[0042] The addition of Au to Pd can not only improve the sensing performance, but also ensure the long-term catalytic stability of the nano-modified layer. By co-modifying the PdO nanofilm structure with Pd-Au, the hydrogen detection sensor can respond to low concentrations of hydrogen more effectively and maintain long-term catalytic stability. The catalytic performance of Pd-Au may be attributed to two aspects: from a kinetic point of view, the addition of Au changes the electronic state of Pd, and generates additional degrees of freedom by forming heteroatom bonds between Pd and Au. Compared with the case of using only nano-Pd modification, the use of Pd-Au nanostructures for synergistic catalysis can more significantly promote the dissociation of hydrogen. From a thermodynamic point of view, the addition of Au causes the Pd lattice to expand, thereby increasing the adsorption capacity of Pd for hydrogen or H. In this case, there are more active H atoms migrating from the catalyst / PdO interface to reduce PdO, so more obvious color differences can be observed.

[0043] In some embodiments, the atomic ratio of Au to Pd is 1: 1 to 1: 4, including but not limited to 1: 4, 1: 3, 3: 5, 1: 2, 2: 3, and 1: 1. Keeping the atomic ratio of Au to Pd in ​​the above range can enable the nano-modified layer to maintain a high catalytic activity and a long-term stable catalytic activity.

[0044] In some embodiments, the substrate 100 of the hydrogen gas detection sensor includes a flexible substrate.

[0045] Traditional hydrogen detection sensors often use rigid materials as substrate materials. In application scenarios that require bending or deformation, the installation process of rigid sensors usually cannot achieve structural conformality, and they are prone to cracking or failure under mechanical stress. Special brackets or protective shells are required, which increases the complexity of installation and maintenance. In some dynamic environments, rigid sensors may also need frequent calibration and maintenance, which limits their application in complex geometric structures. Depositing materials on flexible substrates allows hydrogen detection sensors to be easily installed on curved or irregular surfaces, which is very advantageous in applications that require fitting to complex surfaces, such as wearable devices, robots, and automotive interiors.

[0046] In some embodiments, the thickness of the substrate 100 is 100µm to 300µm, including but not limited to: 100µm, 150µm, 200µm, 250µm, and 300µm.

[0047] In some embodiments, the material of the flexible substrate includes silicone rubber. Silicone rubber is an organic silicon material having the advantages of flexibility, non-toxicity, chemical inertness and environmental friendliness. Using silicone rubber as the base material of the hydrogen detection sensor can make the hydrogen detection sensor exhibit excellent flexibility, enable the hydrogen detection sensor to adapt to various application scenarios with complex geometric configurations, and have excellent durability.

[0048] In some embodiments, the hydrogen detection sensor further includes a protective layer 400. The protective layer 400 is located on the surface of the nano-modified layer 300 away from the color development layer 200. The material of the protective layer 400 includes PMMA. Selecting the above material as the protective layer of the hydrogen detection sensor can effectively block other gas molecules in the air while ensuring that hydrogen can pass through the protective layer 400, thereby achieving a certain hydrogen selectivity.

[0049] In some embodiments, the thickness of the protective layer 400 is 100 nm to 300 nm, including but not limited to: 100 nm, 150 nm, 200 nm, 250 nm, and 300 nm.

[0050] In some embodiments, the thickness of the nano-modified layer 300 is 3 nm to 10 nm, including but not limited to: 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, and 10 nm.

[0051] In some embodiments, the thickness of the color development layer 200 is 30 nm to 60 nm, including but not limited to: 30 nm, 40 nm, 50 nm, and 60 nm.

[0052] The present application also provides a method for preparing the above-mentioned hydrogen detection sensor.

[0053] See also Figure 2 , Figure 2 The preparation flow chart of the hydrogen detection sensor in one embodiment of the present application includes depositing a color development layer 200 on the surface of a substrate 100 and depositing a nano-modification layer 300 on the surface of the color development layer 200 away from the substrate 100 .

[0054] In some embodiments, the color development layer 200 is deposited on the surface of the substrate 100 by a magnetron sputtering process, the target material is a PdO target material with a purity of 99.9%, and the material of the substrate is silicone rubber. The vacuum degree of the inner chamber before deposition is reduced to 1×10 - 6 Torr~3×10 -6 Torr, the applied power is 10 W, and the internal argon pressure is maintained at 0.06 Torr~0.3 Torr. A 30nm~50nm PdO color development layer is deposited on a 2cm×5cm silicone rubber.

[0055] In some embodiments, a magnetron sputtering thin film deposition process is used, and a Pd and Au dual target co-sputtering process is adopted to sputter a Pd-Au nano-modification layer with a thickness of 3nm to 10nm on the PdO color development layer.

[0056] In some embodiments, a protective layer material including PMMA is coated on the surface of the nano-modified layer 300 away from the color-developing layer 200 and dried to form a protective layer 400 on the surface of the nano-modified layer 300 away from the color-developing layer 200.

[0057] In some embodiments, PMMA is melted and spin-coated on the nano-modified layer at a speed of 4000 rpm to 6000 rpm for 20 s to 50 s, and then dried on a hot plate at 50° C. to 80° C. to form a 100 nm to 300 nm thick protective layer 400. PMMA is used to prepare the protective layer, which can provide a highly light-transmitting protective layer for the hydrogen detection sensor, making it easier for users to confirm the color change of the color-developing layer.

[0058] In some embodiments, before depositing the color development layer 200 on the surface of the substrate 100, the method further includes: coating the substrate raw material on the substrate surface and drying to obtain the substrate 100. After forming the protective layer 400, the method further includes: separating the substrate 100 from the substrate to obtain an independent hydrogen detection sensor.

[0059] In some embodiments, the silicone rubber is prepared using a Sylgard 184 two-component silicone rubber raw material. The A component and the B component of Sylgard 184 are mixed in a weight ratio of (9 to 11): 1, and the mixture is spin-coated on the substrate at a speed of 2500 rpm to 4000 rpm for 20 s to 50 s. In order to obtain a dense film, a silicone rubber layer with a thickness of 100 µm to 300 µm is prepared by drying in a vacuum oven at 60°C to 120°C for 2h to 5h.

[0060] The present application is further described in detail below in conjunction with specific embodiments.

[0061] In the following specific embodiments and comparative examples, the raw materials used, unless otherwise specified, are all commercially available products; the instruments used, unless otherwise specified, are all commercially available products; and the processes used, unless otherwise specified, are all routinely selected by those skilled in the art.

[0062] Example 1

[0063] Silicone rubber was prepared using Sylgard 184 two-component silicone rubber raw material. Sylgard 184 component A and component B were mixed at a weight ratio of 10:1 and spin-coated on a 2 cm × 5 cm silicon wafer substrate at 3000 rpm for 30 seconds. The substrate was dried in a vacuum oven at 60 ° C for 3 hours to prepare a flexible substrate with a thickness of 200 µm.

[0064] The color development layer was deposited on the flexible substrate using a magnetron sputtering thin film deposition process, using a 99.9% high-purity PdO target. The vacuum level of the inner chamber before deposition was reduced to 2×10 -6 Torr, the applied power was 10 W, and the internal argon pressure was maintained at 0.1 Torr to deposit a 40 nm PdO metal film.

[0065] The nano-modified layer was deposited on the color-developing layer using a magnetron sputtering thin film deposition process. The vacuum degree of the inner chamber before deposition was reduced to 2×10 -6Torr, the applied power was 10W, and the internal argon pressure was maintained at 0.1 Torr, a 5nm thick Pd-Au composite nano-modification layer was deposited on the PdO film, and the ratio of Au to Pd in ​​the nano-modification layer was 1:2. After sputtering, the PMMA solution was spin-coated on the fabricated film at a speed of 5000rpm, the process time was 30s, and then dried on a hot plate at 60°C to form a 200nm thick PMMA layer. After drying, the flexible substrate of the prepared hydrogen detection sensor was separated from the substrate.

[0066] Comparative Example 1

[0067] The preparation methods of the hydrogen detection sensor in this comparative example are basically the same as those in Example 1, except that: the nano-modification layer only uses nano-Pd, and a 5 nm Pd nano-modification layer is deposited on the PdO film.

[0068] Comparative Example 2

[0069] The preparation methods of the hydrogen detection sensor in this comparative example are basically the same as those in Example 1, except that the protective layer is directly deposited on the color development layer without depositing the nano-modification layer.

[0070] Test Case

[0071] The performance of the hydrogen detection sensor obtained in Example 1 and Comparative Example 1 was tested as follows:

[0072] Fill the test room with air atmosphere with hydrogen so that the volume fraction of hydrogen in the test room reaches 4%. Place the hydrogen detection sensor in the test box and use a high-definition camera to record the color change of the hydrogen detection sensor over time. Use image processing tools to analyze the RGB value of the hydrogen detection sensor and calculate the average value (ΔR) of the change of the R value of multiple points at different times compared with the initial state. In the process of changing from brown to brown, the R value will continue to decrease. The larger the absolute value of ΔR, the greater the color change.

[0073] The performance test data of each embodiment and comparative example are shown in Table 1.

[0074] Table 1

[0075]

[0076] After testing, the hydrogen detection sensor of Example 1 showed the most obvious color change phenomenon at each time point. As can be seen from Table 1, compared with Comparative Example 1 using only Pd and Comparative Example 2 without nanocatalytic particles, Example 1 using Pd-Au to co-modify PdO showed the largest R value change during hydrogen detection, indicating that Pd-Au can effectively promote the color change reaction between PdO and low-concentration hydrogen in an air atmosphere.

[0077] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims, and the description may be used to interpret the content of the claims.

Claims

1. A hydrogen detection sensor, It is characterized in that The invention comprises a substrate, a color development layer and a nano-modification layer, wherein the color development layer is located on the surface of the substrate, and the nano-modification layer is located on the surface of the color development layer away from the substrate; the material of the color development layer comprises PdO, and the material of the nano-modification layer comprises nano-Au and nano-Pd.

2. The hydrogen detection sensor according to claim 1, It is characterized in that In the nano-modified layer, the atomic ratio of Au to Pd is 1:1-1:

4.

3. The hydrogen detection sensor according to claim 1, It is characterized in that The substrate includes a flexible substrate.

4. The hydrogen detection sensor according to claim 3, It is characterized in that The material of the flexible substrate includes silicone rubber.

5. The hydrogen detection sensor according to claim 3, It is characterized in that It also includes a protective layer, which is located on the surface of the nano-modification layer away from the color development layer, and the material of the protective layer includes PMMA.

6. The hydrogen detection sensor according to any one of claims 1 to 5, It is characterized in that The thickness of the nano-modified layer is 3nm-10nm.

7. The hydrogen detection sensor according to any one of claims 1 to 5, It is characterized in that The thickness of the color development layer is 30nm~60nm.

8. A method for preparing a hydrogen detection sensor according to any one of claims 1 to 7, It is characterized in that The steps include: The color development layer is deposited on the surface of the substrate, and the nano-modification layer is deposited on the surface of the color development layer away from the substrate.

9. The method for preparing the hydrogen detection sensor according to claim 8, It is characterized in that Also includes: A protective layer material including PMMA is coated on the surface of the nano-modified layer away from the color-developing layer, and dried to form a protective layer on the surface of the nano-modified layer away from the color-developing layer.

10. The method for preparing the hydrogen detection sensor according to claim 9, It is characterized in that Before depositing the color development layer on the surface of the substrate, the method further includes: coating a substrate raw material on the surface of the substrate, and drying to obtain the substrate; After forming the protective layer, the method further includes: separating the base material from the substrate.

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