Method for preparing a cadmium sulfide-coated tungsten oxide nanocomposite material and method for hydrogen detection

Abstract

The application relates to a preparation method of a cadmium sulfide-coated tungsten oxide nano array composite material and a method for hydrogen, and relates to a cadmium sulfide-coated tungsten oxide nano array composite material and a method thereof. The application realizes preparation of a nano array material by using a chemical deposition method, realizes modification and assembly of the nano material by using electrostatic action, finally applies the synthesized nano array material to preparation of a hydrogen gas sensor, realizes high-sensitivity detection of hydrogen gas, and has the advantages of simple operation, fast reaction speed, good effect, strong selectivity, low cost and the like. The method can be applied to hydrogen energy safety monitoring, hydrogen gas storage and transportation monitoring, hydrogen gas medical treatment and safety monitoring in related chemical and chemical industry fields, and has a strong application prospect in safety monitoring of ion batteries in new energy vehicles and the like.

Description

Technical Field

[0001] This invention relates to a method for preparing cadmium sulfide-coated tungsten oxide nanoarray composite material, and a hydrogen sensing detection method applicable to the field of hydrogen energy safety monitoring. Background Technology

[0002] Currently, the global energy structure is continuously optimizing, and the new energy industry is booming at an unprecedented pace. As an important branch of the new energy industry, hydrogen energy is considered one of the "ultimate energy sources" due to its zero emissions and high energy efficiency. In recent years, the contradiction between the rapid development of the hydrogen energy industry and the lagging development of safety monitoring has led to increasingly prominent problems caused by hydrogen escape. Compared with gasoline and natural gas, hydrogen has a lower density, a higher diffusion coefficient, a lower ignition energy, a wider combustion and explosion range (explosion can occur in the concentration range of 4.0% to 75.6%), and a faster combustion flame speed, making it prone to leakage, flammability, and explosion. If hydrogen leaks and is immediately ignited, it will form a hydrogen jet fire; if it leaks into a confined space, it will easily form a flammable hydrogen cloud, which, once ignited, will produce deflagration and detonation, causing serious harm to the safe operation of equipment and the safety of people's lives and property. Therefore, in order to achieve the goal of hydrogen safety monitoring, scientists have developed a variety of monitoring methods. Among them, high-sensitivity and high-selectivity detection through sensitive materials remains the preferred method, such as sensitive materials like WO3, Pt, and Pd. However, how to further improve the sensitivity and selectivity of hydrogen detection through material design has become a research focus in this field, and also a key link in the storage and real-time monitoring of hydrogen, which is of great significance to the safe use of hydrogen energy.

[0003] Tungsten oxide is an important wide-bandgap semiconductor material with excellent optical and electrical properties, and it has broad application prospects in high-tech fields such as sensors. Tungsten oxide nanoarrays, due to their high specific surface area and excellent electron transport capabilities, are ideal optoelectronic materials. Cadmium sulfide is another commonly used semiconductor material with good optoelectronic properties. It can be used to improve electron transfer and transition capabilities, and is therefore often used to prepare heterojunction materials to enhance sensor performance. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for preparing a cadmium sulfide-coated tungsten oxide nanoarray composite material and a method for highly sensitive hydrogen detection based on this nanocomposite material. This method has the advantages of simple operation, fast reaction speed, good effect, high selectivity and low cost.

[0005] The present invention prepares cadmium sulfide-coated tungsten oxide nanoarray composite material according to the following steps: (1) Synthesis of nano-tungsten oxide array material: FTO electrode modified with WO3 nanorod array was prepared by hydrothermal method; (2) Synthesis of cadmium sulfide-coated tungsten oxide nanoarray composite material: The cleaned tungsten oxide nanoarray material was immersed in 2-2.5 mL of sodium sulfide solution (concentration of 0.25 mol / mL) and 2-2.5 mL of cadmium chloride solution (concentration of 0.25 mol / mL) respectively. The reaction time was 4-6 minutes after each addition of reagents. After rinsing with deionized water and drying, the FTO electrode with cadmium sulfide-coated tungsten oxide nanoarray composite material was obtained.

[0006] This invention detects hydrogen gas according to the following steps: (1) Synthesis of nano-tungsten oxide array material: FTO electrode modified with WO3 nanorod array was prepared by hydrothermal method; (2) Synthesis of cadmium sulfide-coated tungsten oxide nanoarray composite material: The cleaned tungsten oxide nanoarray material was immersed in 2-2.5 mL of sodium sulfide solution (concentration of 0.25 mol / mL) and 2-2.5 mL of cadmium chloride solution (concentration of 0.25 mol / mL) respectively. The reaction time was 4-6 minutes after each addition of reagents. After rinsing with deionized water, it was ready for use. The FTO electrode with cadmium sulfide-coated tungsten oxide nanoarray composite material was obtained. (3) Hydrogen gas is detected by resistance monitoring technology: the concentration of hydrogen gas is detected by the change of the resistance value of the sensitive material under different gas atmospheres.

[0007] The key feature of this invention is the use of chemical deposition to prepare nanoarray materials. These synthesized nanoarray materials are then applied to the fabrication of a hydrogen sensor, enabling sensitive detection of hydrogen. This method offers advantages such as simple operation, fast reaction speed, high efficiency, strong selectivity, and low cost. It can be applied to safety monitoring in hydrogen energy, hydrogen storage and transportation, hydrogen-based medical applications, and related chemical engineering fields, with particularly strong application prospects in the safety monitoring of lithium-ion batteries. Attached Figure Description

[0008] Figure 1 These are actual photos of the device.

[0009] Figure 2 The results are scanning electron microscopy characterizations of the CdS / WO3 sensitive material.

[0010] Figure 3 The response curve of the CdS / WO3-based hydrogen sensor.

[0011] Figure 4 The results show the response calculation of the CdS / WO3-based hydrogen sensor. Detailed Implementation

[0012] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0013] Taking hydrogen as an example, the highly sensitive method for detecting hydrogen based on nanocomposite array materials of the present invention includes the following steps: (1) Synthesis of nano-tungsten oxide array material: WO3 nanorod arrays were prepared by hydrothermal method. FTO (indium tin oxide conductive glass) substrate was immersed in a mixed solution containing 0.04~0.08 mol / L sodium tungstate dihydrate, 0.04~0.08 mol / L oxalic acid solution and 0.8~1.0 mol / L sodium sulfate solution. After reacting at 180~200℃ for 4~6 h, the substrate was taken out and ultrasonically cleaned with deionized water and anhydrous ethanol for 4~6 minutes in sequence. Then, it was annealed at 300~350℃ for 1.5~2 h to obtain FTO electrode modified with WO3 nanorod array.

[0014] (2) Synthesis of cadmium sulfide-coated tungsten oxide nanoarray composite material: The cleaned tungsten oxide nanoarray material was immersed in 2-2.5 mL of sodium sulfide solution (concentration of 0.25 mol / mL) and 2-2.5 mL of cadmium chloride solution (concentration of 0.25 mol / mL) respectively. The reaction time was 4-6 minutes after each addition of reagents. After rinsing with deionized water, it was ready for use. The FTO electrode with cadmium sulfide-coated tungsten oxide nanoarray composite material was obtained. Each reaction requires rinsing with deionized water to remove unreacted ions, followed by drying before use. All reactions were carried out at room temperature (25°C).

[0015] (3) Detection of hydrogen: Hydrogen is detected based on the resistance change of the sensitive material. The specific detection method is as follows: A highly sensitive semiconductor hydrogen sensor was constructed by modifying the FTO electrode with a CdS-coated WO3 nanorod array. The main principle is that the depletion region of the CdS-coated WO3 material widens, thus increasing the initial resistance. When the sensor is exposed to a hydrogen atmosphere, hydrogen molecules react with oxygen adsorbed on the metal oxide surface, releasing electrons, which narrows the depletion region and causes a significant decrease in resistance, thereby enabling detection.

[0016] According to step (3), hydrogen can be detected by the intermolecular interaction between hydrogen and CdS / WO3, based on the hydrogen concentration and the change in resistance of the sensitive material. As the hydrogen concentration increases, the resistance signal decreases, thus achieving quantitative sensing and detection of hydrogen.

[0017] Detection mechanism: The sensor detects hydrogen concentration mainly based on the resistance change of the sensitive material. The surface adsorption of oxygen on the sensitive material and the width of the depletion region of the semiconductor composite material will vary under different hydrogen concentrations. This is mainly due to the reaction of hydrogen with surface adsorbed oxygen and the modulating effect of subsequent injected electrons on the depletion region.

[0018] This detection method based on nanocomposite materials enables sensitive detection of hydrogen. Experimental results show that the intensity of the resistance signal exhibits a linear relationship with the hydrogen concentration in the range of 10–1000 ppm. Based on this linear relationship, quantitative sensing detection of hydrogen can be performed, with improved sensitivity compared to existing methods.

Claims

1. A method for preparing a highly sensitive hydrogen sensor based on nanocomposite materials, characterized in that... The method steps are as follows: (1) Synthesis of nano-tungsten oxide array material: FTO electrode modified with WO3 nanorod array was prepared by hydrothermal method; (2) Synthesis of cadmium sulfide-coated tungsten oxide nanoarray composite material: The cleaned tungsten oxide nanoarray material was immersed in 2-2.5 mL of sodium sulfide solution and 2-2.5 mL of cadmium chloride solution respectively. The reaction time was 4-6 minutes after each addition of reagents. After rinsing with deionized water, it was ready for use. The FTO electrode with cadmium sulfide-coated tungsten oxide nanoarray composite material was obtained. (3) Hydrogen gas is detected by resistance monitoring technology: the concentration of hydrogen gas is detected by the change of the resistance value of the sensitive material under different gas atmospheres.

2. The method for highly sensitive detection of hydrogen based on nanocomposite materials according to claim 1, characterized in that... The steps for preparing the WO3 nanorod array-modified FTO electrode using the hydrothermal method are as follows: The FTO substrate was immersed in a mixed solution containing 0.04-0.08 mol / L sodium tungstate dihydrate, 0.04-0.08 mol / L oxalic acid solution, and 0.8-1.0 mol / L sodium sulfate solution. After reacting at 180-200℃ for 4-6 h, the substrate was removed and ultrasonically cleaned with deionized water and anhydrous ethanol for 4-6 minutes in sequence. Then, it was annealed at 300-350℃ for 1.5-2 h to obtain the FTO electrode modified with WO3 nanorod array.

3. The method for highly sensitive detection of hydrogen based on nanocomposite materials according to claim 2, characterized in that... The volume ratio of sodium tungstate dihydrate, sodium sulfate, and oxalic acid solution is 1:1:

1.

4. The method for highly sensitive detection of hydrogen based on nanocomposite materials according to claim 3, characterized in that... The concentrations of both the sodium sulfide solution and the cadmium chloride solution were 0.25 mol / mL.

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