Hydrogen sensor based on single cerium oxide nanowire and preparation method thereof

Abstract

The invention relates to the technical field of gas sensing, in particular to a hydrogen sensor based on a single cerium oxide nanowire and a preparation method of the hydrogen sensor. The sensor comprises a conductive silver paste dispensing area, a conductive metal coil and a molecular sieve coating area, wherein a cerium oxide nanowire is tightly attached to the surface of a molecular sieve. Compared with a conventional sensor preparation method, the preparation cost is greatly reduced by preparing the cerium oxide nanofiber, and the sensor preparation method is also suitable for other sensing materials; a non-liquid phase in-situ assembly method is used, and compared with liquid phase transfer, the method is more convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensing, and in particular to a hydrogen sensor based on a single cerium oxide nanowire and a preparation method thereof. Background Art

[0002] Hydrogen (H2) is a clean and efficient energy source with important applications in modern industry and energy. However, hydrogen is also a highly flammable and explosive gas, and its detection and monitoring are crucial to ensure safety. Especially in the fields of hydrogen-powered vehicles, fuel cells, industrial production, etc., real-time and accurate detection of hydrogen concentration is the key to preventing safety accidents.

[0003] Traditional hydrogen sensors mainly include semiconductor, electrochemical, thermal conductivity and optical types. These sensors have some limitations in application. For example, semiconductor sensors usually require high operating temperatures, resulting in high energy consumption and are easily affected by ambient humidity and temperature; although electrochemical sensors have high sensitivity, they have slow response times and limited service life; thermal conductivity sensors have low sensitivity when detecting low concentrations of hydrogen; although optical sensors have high accuracy, they have complex structures and high costs. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the deficiencies in the prior art, the present invention provides a hydrogen sensor based on a single cerium oxide nanowire and a preparation method thereof.

[0006] (II) Technical solution

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a hydrogen sensor based on a single cerium oxide nanowire, comprising a conductive silver paste dot coating area, a conductive metal coil, a molecular sieve coating area and a cerium oxide nanowire, wherein the conductive silver paste dot coating area, the conductive metal coil and the molecular sieve coating area are arranged in sequence from left to right, and the cerium oxide nanowire is attached to the surface of the molecular sieve coating area.

[0008] The present invention further provides a method for preparing a hydrogen sensor based on a single cerium oxide nanowire, comprising the following steps:

[0009] Step 1, preparing a single cerium oxide nanowire;

[0010] Step 2, preparing a molecular sieve coated substrate;

[0011] Step 3, using conductive silver paste to fix the nanowires;

[0012] Step 4: Prepare a hydrogen sensor.

[0013] Preferably, the step 1 includes the following detailed steps:

[0014] Step a1, weigh 217 mg of cerium nitrate, dissolve the cerium nitrate in ethanol or DMF, add 0.4 g of polyvinyl pyrrolidone, and stir with a magnetic stirrer for 6 hours to obtain an electrospinning solution;

[0015] Step a2, the spinning solution is loaded into a syringe and installed on an electrospinning device for spinning, and then the fibers are collected, and the nanofibers are collected on a receiving plate. The parameters of the electrospinning device are set as follows: high voltage power supply: 18-20 kV; injection rate: 0.5-0.7 mL·h-1; receiving distance: 15 cm;

[0016] Step a3: Dry the collected nanofibers in an oven at 60-80°C for 12 hours, and then heat-treat them by calcining them at 500°C in air for 150 minutes to obtain cerium oxide nanowires.

[0017] Preferably, the step 2 includes the following detailed steps:

[0018] Step b1, weigh 2 mg of molecular sieve, dissolve it in ethanol and grind it until it is completely dissolved to obtain a molecular sieve solution;

[0019] Step b2, fix the ceramic tube and evenly apply the molecular sieve solution with a brush;

[0020] Step b3: After coating, place the ceramic tube in an oven for low-temperature drying.

[0021] Preferably, the step 3 includes the following detailed steps:

[0022] Step c1, the prepared nanowires are first spun on a regularly shaped iron plate, and then the cerium oxide nanowires are transferred to the surface of the ceramic tube substrate in an air environment;

[0023] Step c2, preparing a colloidal solution containing silver particles, and evenly coating it on both ends of the cerium oxide nanowire array;

[0024] Step c3: placing the ceramic tube in a drying oven for curing to fix the nanowires.

[0025] Preferably, step 4 includes the following detailed steps:

[0026] Step d1, welding the nanowire ceramic tube obtained in step c3 to a bakelite base, and welding four metal pins;

[0027] Step d2: Pass the resistance wire through the ceramic tube and weld it to the base. After welding, use a multimeter to measure the resistance value at both ends of the resistance wire to ensure that its resistance range is 0-1Ω.

[0028] (III) Beneficial effects

[0029] Compared with the prior art, the present invention provides a hydrogen sensor based on a single cerium oxide nanowire and a preparation method thereof, which has the following beneficial effects:

[0030] 1. High sensitivity: The high surface area to volume ratio and unique electronic properties of cerium oxide nanowires make them extremely sensitive to detection targets and can detect low concentrations of chemicals or biological molecules.

[0031] 2. Fast response: Due to the extremely small size of nanowires, the sensor can quickly respond to changes in the environment and provide instant detection results.

[0032] 3. Low power consumption: The operation of a single cerium oxide nanowire sensor generally requires very low power consumption, which makes it advantageous in portable and remote monitoring applications.

[0033] 4. High selectivity: In this preparation method, the functionalization of cerium oxide nanowires is simple. By functionalizing the surface of cerium oxide nanowires, the selectivity of the sensor for specific target molecules can be improved and the influence of interferences can be reduced.

[0034] 6. Mechanical flexibility: Cerium oxide nanowires have good mechanical flexibility and can be used in flexible electronic devices and wearable devices.

[0035] 7. Chemical stability: Cerium is a rare earth element with excellent chemical stability and corrosion resistance, ensuring the long-term stable operation of the sensor in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the structure of a hydrogen sensor with a single cerium oxide nanowire according to the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of the cerium oxide nanowire receiving plate of the present invention;

[0038] Figure 3 This is a morphological image of a single cerium oxide nanowire of the present invention;

[0039] Figure 4 This is an element mapping image of a single cerium oxide nanowire of the present invention;

[0040] Figure 5 This is a performance diagram of a hydrogen gas sensor of a single cerium oxide nanowire at 250° C. of the present invention;

[0041] Figure 6 It is the recovery response time of the hydrogen sensor of a single cerium oxide nanowire of the present invention at 250°C.

[0042] In the figure: 1 conductive silver paste dot coating area, 2 conductive metal coil, 3 cerium oxide nanowire, 4 molecular sieve coating area, 5 receiving plate coil spacing. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] See also Figure 1-6 A hydrogen sensor based on a single cerium oxide nanowire includes a conductive silver paste dot coating area 1, a conductive metal coil 2, a molecular sieve coating area 4 and a cerium oxide nanowire 3. The conductive silver paste dot coating area 1, the conductive metal coil 2 and the molecular sieve coating area 4 are arranged from left to right in sequence, and the cerium oxide nanowire 3 is attached to the surface of the molecular sieve coating area 4.

[0045] The present invention further provides a method for preparing a hydrogen sensor based on a single cerium oxide nanowire, comprising the following steps:

[0046] Step 1, preparing a single cerium oxide nanowire;

[0047] Step 2, preparing a molecular sieve coated substrate;

[0048] Step 3, using conductive silver paste to fix the nanowires;

[0049] Step 4: Prepare a hydrogen sensor.

[0050] Preferably, the step 1 includes the following detailed steps:

[0051] Step a1, polyvinyl pyrrolidone (PVP): a water-soluble polymer, soluble in water and a variety of organic solvents (such as ethanol, methanol, acetic acid, etc.), with excellent film-forming properties, adhesion and wettability, weigh 217 mg of cerium nitrate, dissolve the cerium nitrate in ethanol or DMF, add 0.4 g of polyvinyl pyrrolidone, use a magnetic stirrer to stir at an appropriate temperature for 6 hours, and obtain an electrospinning solution;

[0052] Step a2, connect the power supply and the injection pump, adjust the voltage and flow rate, load the spinning solution into the syringe and install it on the electrospinning device; the electrospinning device setting parameters are: high voltage power supply: 18-20kV; injection rate: 0.5-0.7mL·h-1; receiving distance: 15cm, load the spinning solution into the syringe and install it on the electrospinning device for spinning, then collect the fibers, and collect the nanofibers on the receiving plate;

[0053] Step a3: Dry the collected nanofibers in an oven at 60-80°C for 12 hours, and then heat-treat them by calcining them at 500°C in air for 150 minutes to obtain cerium oxide nanowires.

[0054] Characterization:

[0055] SEM was used to characterize the fiber morphology and structure, and XRD was used to analyze the crystal structure.

[0056] Preferably, the step 2 includes the following detailed steps:

[0057] Step b1, weigh 2 mg of molecular sieve, dissolve it in ethanol and grind it until it is completely dissolved to obtain a molecular sieve solution;

[0058] Step b2, fix the ceramic tube and evenly apply the molecular sieve solution with a brush;

[0059] Step b3: After coating, place the ceramic tube in an oven for low-temperature drying.

[0060] Preferably, the step 3 includes the following detailed steps:

[0061] Step c1, the prepared nanowires are first spun on a regularly shaped iron plate, and then the cerium oxide nanowires are transferred to the surface of the ceramic tube substrate in an air environment;

[0062] Step c2, preparing a colloidal solution containing silver particles, and evenly coating it on both ends of the cerium oxide nanowire array;

[0063] Step c3: placing the ceramic tube in a drying oven for curing to fix the nanowires.

[0064] Preferably, step 4 includes the following detailed steps:

[0065] Step d1, welding the nanowire ceramic tube obtained in step c3 to a bakelite base, and welding four metal pins;

[0066] Step d2: Pass the resistance wire through the ceramic tube and weld it to the base. After welding, use a multimeter to measure the resistance value at both ends of the resistance wire to ensure that its resistance range is 0-1Ω.

[0067] like Figure 1 As shown, a hydrogen sensor based on a single cerium oxide nanowire. The two ends of the outer front of the ceramic tube are the nanowire fixing areas with conductive silver paste, 2 is a conductive metal coil, the middle part 3 is the molecular sieve coating area, and 4 is the cerium oxide nanowire, which is tightly attached to the surface of the molecular sieve;

[0068] like Figure 2 As shown, cerium oxide nanowires are spun onto a receiving plate having a coil spacing 5 of 9 mm.

[0069] like Figure 3 As shown, from the scanning image of the ceramic tube consumables, it can be clearly seen that cerium oxide nanowires are spun on the surface of the ceramic tube.

[0070] like Figure 4 As shown, cerium is uniformly distributed in the cerium oxide nanofiber skeleton.

[0071] like Figure 5 As shown, the dynamic response of a hydrogen sensor based on a single cerium oxide nanowire in a temperature environment of 250°C (hydrogen concentration 10ppm) is obvious and the performance is stable. The performance remains unchanged after three cycles.

[0072] like Figure 6 The figure shows the response / recovery speed of a single cerium oxide nanowire hydrogen sensor. The cerium oxide nanowire sensor can quickly complete the adsorption and desorption of hydrogen within 4 seconds, which is mainly due to the unique properties of a single cerium oxide nanowire. At the same time, the SBA-15 coating has little effect on the response / recovery speed.

[0073] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0074] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0075] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A hydrogen sensor based on a single cerium oxide nanowire, characterized in that: It includes a conductive silver paste dot coating area, a conductive metal coil, a molecular sieve coating area and cerium oxide nanowires, wherein the conductive silver paste dot coating area, the conductive metal coil and the molecular sieve coating area are arranged in sequence from left to right, and the cerium oxide nanowires are attached to the surface of the molecular sieve coating area.

2. A method for preparing a hydrogen sensor based on a single cerium oxide nanowire, characterized in that: The steps include: Step 1, preparing a single cerium oxide nanowire; Step 2, preparing a molecular sieve coated substrate; Step 3, using conductive silver paste to fix the nanowires; Step 4: Prepare a hydrogen sensor.

3. The method for preparing a hydrogen sensor based on a single cerium oxide nanowire according to claim 2, characterized in that: The step 1 includes the following detailed steps: Step a1, weigh 217 mg of cerium nitrate, dissolve the cerium nitrate in ethanol or DMF, add 0.4 g of polyvinyl pyrrolidone, and stir with a magnetic stirrer for 6 hours to obtain an electrospinning solution; Step a2, the spinning solution is loaded into a syringe and installed on an electrospinning device for spinning, and then the fibers are collected, and the nanofibers are collected on a receiving plate. The parameters of the electrospinning device are set as follows: high voltage power supply: 18-20 kV; injection rate: 0.5-0.7 mL·h-1; receiving distance: 15 cm; Step a3: Dry the collected nanofibers in an oven at 60-80°C for 12 hours, and then heat-treat them by calcining them at 500°C in air for 150 minutes to obtain cerium oxide nanowires.

4. The method for preparing a hydrogen sensor based on a single cerium oxide nanowire according to claim 3, characterized in that: The step 2 includes the following detailed steps: Step b1, weigh 2 mg of molecular sieve, dissolve it in ethanol and grind it until it is completely dissolved to obtain a molecular sieve solution; Step b2, fix the ceramic tube and evenly apply the molecular sieve solution with a brush; Step b3: After coating, place the ceramic tube in an oven for low-temperature drying.

5. The method for preparing a hydrogen sensor based on a single cerium oxide nanowire according to claim 4, characterized in that: The step 3 includes the following detailed steps: Step c1, the prepared nanowires are first spun onto a regularly shaped iron plate, and then the cerium oxide nanowires are transferred to the surface of the ceramic tube substrate in an air environment; Step c2, preparing a colloidal solution containing silver particles, and evenly coating it on both ends of the cerium oxide nanowire array; Step c3: placing the ceramic tube in a drying oven for curing to fix the nanowires.

6. The method for preparing a hydrogen sensor based on a single cerium oxide nanowire according to claim 5, characterized in that: The step 4 includes the following detailed steps: Step d1, welding the nanowire ceramic tube obtained in step c3 to a bakelite base, and welding four metal pins; Step d2: Pass the resistance wire through the ceramic tube and weld it to the base. After welding, use a multimeter to measure the resistance value at both ends of the resistance wire to ensure that its resistance range is 0-1Ω.

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