Preparation method and application of AuPd alloy nanoparticle doped ZnO sensing material

Abstract

The invention relates to a preparation method and application of an AuPd alloy nanoparticle doped ZnO sensing material, and belongs to the field of gas sensing. According to the invention, sodium hydroxide is used as a solution to provide an alkaline environment, zinc nitrate hexahydrate is used as a zinc source, chloroauric acid and palladium chloride are used as a gold source and a palladium source, deionized water is used as a solvent, and the AuPd-ZnO gas-sensitive sensing material is prepared through the steps of mechanical stirring, microwave-assisted hydrothermal method synthesis, centrifugation, drying and the like. The sensor based on the AuPd-doped ZnO nano material has good gas-sensitive performance on acetone, and has high response, ideal stability and good selectivity. The response to 50 ppm ethanol is 32, the lower limit of detection is 5 ppm, and high stability is shown in a continuous peripheral gas-sensitive test. The method is simple in preparation process, low in equipment requirement and high in controllable degree, and the obtained product is uniform, has excellent gas-sensitive performance, can realize trace detection of ethanol and can be used as an ideal sensing device for ethanol detection.

Description

Technical Field

[0001] The invention belongs to the field of gas sensing applied to gas detection, and specifically relates to a preparation method and application of an AuPd alloy nanoparticle-doped ZnO sensing material. Background Art

[0002] Ethanol is a typical volatile organic compound with strong volatility and flammability. At the same time, as one of the most commonly used alcohols, it has a significant impact on human life and industrial processes, and is widely used in food processing, medical and health services, and chemical production industries. According to data information provided by the Occupational Safety and Health Administration, the maximum permissible exposure limit for ethanol is 1000ppm. Long-term exposure to ethanol gas can cause breathing difficulties, brain dysfunction, and increased liver load. Therefore, the development of new ethanol gas sensors is of great significance to human life. Summary of the invention

[0003] The present invention provides a preparation method and application of AuPd alloy nanoparticle doped ZnO sensing material. The prepared AuPd alloy nanoparticle doped ZnO sensing material sensor has good gas-sensitive performance to ethanol, high response, ideal stability and good selectivity.

[0004] The technical solution of the present invention is:

[0005] A method for preparing a ZnO sensing material doped with AuPd alloy nanoparticles, the method comprising: weighing zinc nitrate hexahydrate and sodium hydroxide in molar ratio, synthesizing by mechanical stirring and microwave-assisted hydrothermal method, centrifuging, and drying to obtain a ZnO nanosensing material,

[0006] The specific steps are as follows:

[0007] Step 1: Prepare zinc nitrate solution: add 2 mmol Zn(NO3)2·6H2O and 17.5 ml deionized water into a 100 ml beaker and place on a magnetic stirring table for stirring;

[0008] Step 2: Prepare sodium hydroxide solution: add 18 mmol NaOH and 17.5 ml deionized water into a 100 ml beaker and place on a magnetic stirring table for stirring;

[0009] Step 3, mixed solution: under magnetic stirring, pour the sodium hydroxide solution into the zinc nitrate solution, continue stirring until the mixed solution becomes uniform milky white, transfer to a 50 ml high pressure reactor, and heat in a constant temperature oven at 200° C. for 24 h;

[0010] Step 4, centrifugal washing and annealing: after the reaction is completed, the precursor is collected by centrifugation and washed alternately with ethanol and deionized water, dried in air at 80°C for 12 hours, ground and sintered in a muffle furnace at 500°C for 2 hours, with a heating rate of 2°C / min, and ZnO nanomaterials are obtained when the muffle furnace is naturally cooled to room temperature;

[0011] Step 5, synthesis of AuPd alloy nanoparticles: 1.49g sodium citrate and 1.39g hydroxylamine hydrochloride were dissolved in 40ml deionized water, stirred for 10min, then transferred to a 100℃ water bath for heating, and stirred for 10min. Then, 66ml chloroauric acid solution and 0.03g PdCl2 were added, stirred, and small black particles were precipitated; after centrifugation, washing and collection, AuPd alloy nanoparticles were obtained after simple heat treatment at 500℃;

[0012] Step six, loading AuPd alloy nanoparticles on the surface of ZnO nanomaterials: dissolve 0.4g ZnO sample in 5ml ethanol, then add 0.001g, 0.002g, and 0.004g AuPd alloy nanoparticles respectively, stir for 40min, and dry the sample in a constant temperature drying oven at 60°C for 10h. Finally, obtain AuPd-ZnO composite materials with different mass percentages.

[0013] Furthermore: AuPd alloy nanoparticles loaded with ZnO nanosensing material are in the form of a composite of nanosheets and nanorods.

[0014] The invention discloses an application of an AuPd-ZnO composite material prepared by a method for preparing an AuPd alloy nanoparticle-doped ZnO nanosensing material in ethanol detection.

[0015] The beneficial effects of the present invention include:

[0016] The material has the following characteristics: (1) high sensitivity and low detection limit (2) ideal repeatability and stability (3) easy preparation and portable use. The introduction of AuPd alloy nanoparticles greatly improves the gas-sensitive response of the sensor to acetone.

[0017] An AuPd alloy nanoparticle doped ZnO nanosensing material was studied for ethanol detection. Based on the original high specific surface area, by doping AuPd alloy nanoparticles in different proportions, the response to ethanol was improved, the detection limit was reduced, and the selectivity was optimized. The AuPd alloy nanoparticle doped ZnO nanomaterial gas sensor prepared by the present invention has great application potential in industrial detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1XRD diagrams of AuPd-ZnO nanomaterials with different doping amounts prepared in the embodiments of the present invention;

[0019] Figure 2 This is a transmission electron microscope (TEM) photograph of a 0.5% AuPd-ZnO nanomaterial prepared in an embodiment of the present invention;

[0020] Figure 3 XPS spectra of 0.5% AuPd-ZnO nanomaterials prepared in the embodiment of the present invention; (a) is the full XPS spectrum, (b) is the fine spectrum of Zn element, (c) is the fine spectrum of O element, and (d) is the fine spectrum of Au element and Pd element;

[0021] Figure 4 The graphs are response curves of AuPd-ZnO nanomaterial gas sensors with different doping amounts prepared in the embodiments of the present invention to 50 ppm ethanol gas at different temperatures. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and schematic diagrams of experimental phenomena.

[0023] Example 1 is a one-step hydrothermal method for preparing ZnO nanomaterials and AuPd-ZnO composite nanomaterials.

[0024] In this embodiment, the following steps are mainly performed:

[0025] Step 1: Prepare zinc nitrate solution: add 0.594 g Zn(NO3)2〃6H2O and 17.5 ml deionized water into a 100 ml beaker and place on a magnetic stirring table for stirring;

[0026] Step 2: Prepare sodium hydroxide solution: add 0.72 g NaOH and 17.5 ml deionized water into a 100 ml beaker and place on a magnetic stirring table for stirring;

[0027] Step 3, mixed solution: under magnetic stirring, pour the sodium hydroxide solution into the zinc nitrate solution, continue stirring until the mixed solution becomes uniform milky white, transfer to a 50 ml high pressure reactor, and heat in a constant temperature oven at 200° C. for 24 h;

[0028] Step 4, centrifugal washing and annealing: After the reaction is completed, the precursor is collected by centrifugation and washed alternately with ethanol and deionized water, and dried in air at 80°C for 12 hours. The dried precursor is ground and sintered in a muffle furnace at 500°C for 2 hours, with a heating rate of 2°C / min. When the muffle furnace is naturally cooled to room temperature, ZnO nanomaterials are obtained;

[0029] Step 5, synthesis of AuPd alloy nanoparticles: Dissolve 1.49g sodium citrate and 1.39g hydroxylamine hydrochloride in 40ml deionized water, stir for 10min, then transfer to a 100℃ water bath for heating, and continue stirring for 10min. Then, add 66ml chloroauric acid solution (4.5mmol / L) and 0.03g PdCl2, stir, and small black particles precipitate. After centrifugation, washing and collection, AuPd alloy nanoparticles are obtained after a simple heat treatment at 500℃;

[0030] Step six, loading AuPd alloy nanoparticles on the ZnO surface: 0.4 g of ZnO sample was dissolved in 5 ml of ethanol, and 0.25% by mass (0.001 g) of AuPd alloy nanoparticles were added.

[0031] In step six, the AuPd-ZnO composite material with 0.25 wt % AuPd-ZnO can be obtained.

[0032] Example 2 is different from Example 1. In step 6, AuPd alloy nanoparticles are loaded on the surface of ZnO: a certain amount of ZnO sample is dissolved in 5 ml of ethanol, and 0.5% by mass (0.002 g) of AuPd alloy nanoparticles are added.

[0033] In step six, the AuPd-ZnO composite material with 0.5 wt % AuPd-ZnO can be obtained.

[0034] Example 3 is different from Example 1. In step 6, AuPd alloy nanoparticles are loaded on the surface of ZnO: a certain amount of ZnO sample is dissolved in 5 ml of ethanol, and 1% by mass (0.004 g) of AuPd alloy nanoparticles are added.

[0035] In step six, the AuPd-ZnO composite material with 1 wt% AuPd-ZnO can be obtained.

[0036] Figure 1 The XRD patterns of AuPd-ZnO nanosheets prepared with different doping amounts of AuPd alloy nanoparticles; Figure 1 It can be seen that, it can be clearly seen that, except for the ZnO peak, there are no additional diffraction peaks, indicating that the prepared ZnO and AuPd-ZnO composite materials are also pure phases.

[0037] Figure 2 This is the transmission electron microscope (TEM) photo of the prepared 0.5% AuPd-ZnO nanomaterial;

[0038] Figure 3XPS spectra of prepared pure ZnO and 0.5% AuPd-ZnO nanomaterials; (a) is the full XPS spectrum, (b) is the fine spectrum of Zn element, (c) is the fine spectrum of O element, and (d) is the fine spectrum of Au element and Pd element;

[0039] In order to confirm the surface element composition and determine the chemical state of the elements, the samples were subjected to XPS tests. It can be seen from the XPS total spectrum that all elements are present, and the chemical state of the elements can be seen from the fine spectrum. The proportions of adsorbed oxygen in ZnO and 0.5wt% AuPd-ZnO are 28.44% and 37.48%, respectively, indicating that the incorporation of AuPd alloy nanoparticles can increase the proportion of adsorbed oxygen. The proportion of adsorbed oxygen has a great influence on the gas sensing performance of the sensor. The increase in the proportion of adsorbed oxygen can improve the sensing performance of ethanol. The high-resolution spectra of Au and Pd in ​​the 0.5wt% AuPd-ZnO material are shown. The fitting peaks of the Au 4f spectrum at 84.9eV and 88.3eV correspond to Au 4f 7 / 2 and Au 4f 5 / 2 The fitted peaks of the Pd 3d spectrum at 335.6 eV and 341.3 eV correspond to the Pd 3d 5 / 2 and Pd 3d 3 / 2 ;

[0040] Figure 4 The response curves of AuPd-ZnO gas sensors with different AuPd alloy nanoparticle doping amounts to 50ppm ethanol gas at different temperatures are shown in the figure. As shown in the figure, the response of AuPd-ZnO sensors to ethanol is significantly improved. At the optimal working temperature, the responses of pure ZnO and 0.5wt% AuPd-ZnO sensors are 17 and 32, respectively, and the response to ethanol is improved by about 1.88 times.

Claims

1. A method for preparing AuPd alloy nanoparticles doped with ZnO sensing material, characterized in that: The method comprises: weighing zinc nitrate hexahydrate and sodium hydroxide in molar ratio, synthesizing by mechanical stirring and microwave-assisted hydrothermal method, centrifuging, and drying to prepare ZnO nanosensing material, The specific steps are as follows: Step 1: Prepare zinc nitrate solution: add 2 mmol Zn(NO3)2·6H2O and 17.5 ml deionized water into a 100 ml beaker and place on a magnetic stirring table for stirring; Step 2: Prepare sodium hydroxide solution: add 18 mmol NaOH and 17.5 ml deionized water into a 100 ml beaker and place on a magnetic stirring table for stirring; Step 3, mixed solution: under magnetic stirring, pour the sodium hydroxide solution into the zinc nitrate solution, continue stirring until the mixed solution becomes uniform milky white, transfer to a 50 ml high pressure reactor, and heat in a constant temperature oven at 200° C. for 24 h; Step 4, centrifugal washing and annealing: after the reaction is completed, the precursor is collected by centrifugation and washed alternately with ethanol and deionized water, dried in air at 80°C for 12 hours, ground and sintered in a muffle furnace at 500°C for 2 hours, with a heating rate of 2°C / min, and ZnO nanomaterials are obtained when the muffle furnace is naturally cooled to room temperature; Step 5, synthesis of AuPd alloy nanoparticles: 1.49g sodium citrate and 1.39g hydroxylamine hydrochloride were dissolved in 40ml deionized water, stirred for 10min, then transferred to a 100℃ water bath for heating, and stirred for 10min. Then, 66ml chloroauric acid solution and 0.03g PdCl2 were added, stirred, and small black particles were precipitated; after centrifugation, washing and collection, AuPd alloy nanoparticles were obtained after simple heat treatment at 500℃; Step six, loading AuPd alloy nanoparticles on the surface of ZnO nanomaterials: dissolve 0.4g ZnO sample in 5ml ethanol, then add 0.001g, 0.002g, and 0.004g AuPd alloy nanoparticles respectively, stir for 40min, and dry the sample in a constant temperature drying oven at 60°C for 10h. Finally, obtain AuPd-ZnO composite materials with different mass percentages.

2. The method for preparing the AuPd alloy nanoparticle-loaded ZnO nanosensor material according to claim 1, characterized in that: The AuPd alloy nanoparticle-loaded ZnO nanosensing material is in the form of a composite of nanosheets and nanorods.

3. Use of the AuPd-ZnO composite material prepared by the method for preparing the AuPd alloy nanoparticle-doped ZnO nanosensing material according to claim 1 or 2 in ethanol detection.

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