Preparation method and application of Ni2P / NiO heterostructure nanosheet gas sensitive material

Abstract

The invention provides a preparation method and application of a Ni2P / NiO heterostructure nanosheet gas sensitive material, and the preparation method comprises the following steps: based on a BP nanosheet obtained in advance, dispersing the BP nanosheet in 1-methyl-2-pyrrolidone to obtain a dispersion liquid A; the preparation method comprises the following steps: dispersing a certain amount of metal salt in 1-methyl-2-pyrrolidone, mixing the dispersion liquid A and the dispersion liquid C, and uniformly stirring to obtain a reaction precursor; and placing the precursor mixed solution in a flask, placing the flask in an experimental microwave oven under the protection of an argon atmosphere, carrying out microwave heating reaction for a period of time, and centrifugally cleaning the reactant with ethanol to obtain the Ni2P / NiO heterostructure nanosheet subjected to in-situ topological transformation. According to the preparation method and application of the Ni2P / NiO heterostructure nanosheet gas-sensitive material, the Ni2P / NiO heterostructure nanosheet gas-sensitive material is obtained by adopting a two-step method of microwave in-situ topological transformation and high-temperature oxidation, and the original two-dimensional nanosheet morphology of BP is reserved, so that the gas sensitivity of the gas-sensitive material to H2S is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of gas sensitivity sensing, and in particular to a Ni 2 Preparation method and application of P / NiO heterostructure nanosheet gas-sensitive materials. Background Art

[0002] With the development of society and the advancement of science and technology, the advancement of global industrialization has led to the over-exploitation of resources and the emission of polluting gases, which has caused serious damage to the ecological environment and has affected human health and sustainable development. Monitoring polluting gases is the fundamental source for effectively controlling gas emissions and purifying the atmospheric environment. Among them, H 2 S gas is an inevitable toxic gas in industrial production, agricultural activities and microbial decomposition. 2 The effective detection and real-time monitoring of S have become the needs of industrial production and daily life. Based on this, exploring and developing cheap, highly reactive and durable gas sensors has become the focus of achieving detection. Currently, common gas-sensitive sensing materials have the problems of high production and preparation costs, high effective working temperature and long response time, which cannot meet the needs of real-time and rapid detection of target gases.

[0003] Metal oxide semiconductor materials, such as NiO, SnO 2 , ZnO, etc. have shown certain performance application potential in the field of gas sensing, but a single metal oxide has a specific electronic structure and coordination environment, which leads to a series of defects such as certain response, but often limited by temperature and concentration, and poor stability. Therefore, constructing an adjustable heterostructure is expected to achieve adjustable gas sensitive properties. Among them, transition metal phosphides show some metallic properties and can provide the same sensitization properties as precious metals. Therefore, this metal phosphide composite material with advantages such as good conductivity, stable structure, and easy preparation is expected to become a promising material for improving NiO-based H 2 S is an advantageous material for gas-sensitive materials. In addition, since O has a higher electronegativity than P, under high-temperature oxidation conditions, O has the possibility of replacing P in metal phosphorus compounds. Therefore, the in-situ preparation of metal phosphide and oxide heterojunctions can not only achieve electronic structure regulation, but also ensure interface lattice adaptation and achieve structural stability.

[0004] Therefore, it is necessary to provide a Ni 2 The preparation method of P / NiO heterostructure nanosheet gas-sensitive material solves the above technical problems. Summary of the invention

[0005] The present invention provides a Ni 2The preparation method of P / NiO heterostructure nanosheet gas-sensitive materials solves the problems of high production and preparation cost, high effective working temperature, long recovery time, and inability to meet the needs of real-time and rapid detection of target gases in currently common gas-sensitive sensing materials.

[0006] In order to solve the above technical problems, the present invention provides a Ni 2 The method for preparing a P / NiO heterostructure nanosheet gas-sensitive material comprises the following steps: S1. Dispersing the BP nanosheets obtained in advance in 1-methyl-2-pyrrolidone, which is referred to as dispersion A; dispersing a certain amount of metal salt in 1-methyl-2-pyrrolidone, which is referred to as dispersion C; mixing dispersions A and C and stirring them evenly to obtain a reaction precursor; S2. Place the precursor mixture in a flask and place it in an experimental microwave oven under the protection of an argon atmosphere. Heat the reaction with microwaves for a period of time. Wash the reactants with ethanol by centrifugation to obtain the in-situ topologically transformed Ni 2 P / NiO heterostructure nanosheets; S3, the intermediate product Ni 2 P / NiO heterostructure nanosheets were placed in an air furnace for high-temperature calcination, and then oxidized to obtain in-situ transformed Ni 2 P / NiO heterostructure nanosheets.

[0007] Preferably, the dispersion A in S1 is prepared by dispersing 20 mg of BP nanosheets in every 20 mL of 1-methyl-2-pyrrolidone.

[0008] Preferably, the dispersion C in S2 contains a metal salt of NiCl2·6H 2 O, 2.6146 g NiCl2·6H2O dispersed in 10 mL 1-methyl-2-pyrrolidone 2 O metal salts.

[0009] Preferably, the microwave heating power in S2 is 800 W and the reaction time is 10 min.

[0010] Preferably, the calcination temperature in the air furnace in S3 is 650° C., and the calcination time is selected in the range of 0 to 16 hours.

[0011] Preferably, the metal salt in S1 further comprises a phosphorus source-related metal salt, wherein the phosphorus source-related metal salt is selected from at least one of sodium phosphate, potassium phosphate and sodium phosphite, and is used to control the phosphorus content in the product, thereby optimizing Ni 2 Gas sensing properties of P / NiO heterostructure nanosheets.

[0012] Preferably, the air humidity in the S3 air furnace is controlled within a specified range to prevent water vapor from adversely affecting the high-temperature calcination process and product structure.

[0013] A Ni 2 Application of P / NiO heterostructure nanosheet gas sensing materials, using the Ni 2 Preparation method of P / NiO heterostructure nanosheet gas sensing material 2 P / NiO heterostructure nanosheet gas sensing material, the Ni 2 P / NiO heterostructure nanosheets as gas-sensitive materials for detecting H 2 S.

[0014] Compared with the related art, the present invention provides a Ni 2 The preparation method of P / NiO heterostructure nanosheet gas-sensitive material has the following beneficial effects: The present invention provides a Ni 2 The preparation method of P / NiO heterogeneous structure nanosheet gas-sensitive material adopts a two-step method of microwave in-situ topological transformation and high-temperature oxidation to obtain it, retaining the original two-dimensional nanosheet morphology of BP and transforming it into Ni 2 P / NiO heterostructure nanosheets make it suitable for H 2 The gas sensitivity of S is greatly improved.

[0015] The excessive amount of Ni metal source used in S1 of the present invention is to meet the basic requirements of in-situ topological transformation. 2 6H 2 O solution, the Ni source can be continuously provided to the reaction, resulting in Ni 2 P / NiO basically retains the original two-dimensional morphology of BP. And due to undersaturation, some BP and Ni sources are not fully combined, and many micropore defects are generated on the surface of the heterostructure. The above two points are beneficial to the contact between gas and device and gas conduction in the process of gas sensitive detection. On the other hand, the high temperature calcination method with Ni 2 P / NiO heterostructure as a precursor, the obtained Ni 2 P / NiO retains the original two-dimensional morphology and forms Ni 2 P-modified Ni 2 The P / NiO heterostructure has an adjustable electronic structure and is conducive to providing higher carrier mobility. It can play a synergistic role in enabling the heterostructure material to exhibit excellent gas sensitive sensing performance.

[0016] The Ni of the present invention 2P / NiO heterostructured nanosheets present a thinner two-dimensional nanosheet morphology with high surface exposure, which can provide more adsorption and desorption sites for the target gas, thus having high response sensitivity. 2 The nn heterostructure formed between P and NiO produces an adjustable electronic state, which makes the material body conducive to the adsorption and desorption response of specific gases.

[0017] The Ni of the present invention 2 P / NiO heterostructure nanosheets for assembling gas sensitive sensors for H 2 S gas detection, with ppm level H 2 S gas response, the response is rapid, and the recovery time is short, which shows that the Ni 2 P / NiO heterostructure nanosheets have excellent H 2 S gas sensing sensitivity. In addition, after long-term sensitivity stability testing, the Ni 2 P / NiO heterostructured nanosheets have a durability of up to 5 weeks without obvious attenuation. In order to further evaluate the heterostructured nanosheets for H 2 High selectivity of S gas, introduction of NH 3 and CO as a control gas, the results show that the Ni 2 P / NiO heterostructure nanosheets have extremely high sensitivity to H2S and are suitable for preventing H2S in industry. 2 S is a special value for gas leakage prevention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention provides a Ni 2 A schematic structural diagram of a preferred embodiment of a method for preparing a P / NiO heterostructure nanosheet gas-sensitive material; Figure 2 (a) Ni of Example 6 2 P / Ni1 2 P5 heterostructure, (b) Ni of Example 1 2 P / NiO-4h heterostructure and (c) Ni in Example 2 2 Transmission electron microscopy (TEM) images of P / NiO-16h heterostructure; Figure 3 (a) Ni of Example 6 2 P / Ni1 2 P5 heterostructure, (b) Ni of Example 1 2 P / NiO-4h heterostructure and (c) Ni in Example 2 2 High-resolution TEM (HRTEM) image of P / NiO-16h heterostructure; Figure 4 Gas sensitivity tests of samples prepared for Example 1, Example 2 and Example 6: (a) Example 1 was exposed to 5 ppm H at different temperatures. 2 The response-recovery curve when S gas is present, (b) is the gas sensing performance exhibited by Example 1, Example 2 and Example 6 at a temperature of 150°C; Figure 5 Preparation of Ni for Example 1 2 (a) Short-term response recovery and (b) long-term sensitivity stability test diagram of P / NiO-4h heterostructure; Figure 6 Ni prepared in Example 1 and Example 2 2 P / NiO heterostructure nanosheets for different gases H 2 S. NH 3 And CO gas sensitivity response curve test. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0020] First embodiment Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 ,in, Figure 1 The present invention provides a Ni 2 A schematic structural diagram of a preferred embodiment of a method for preparing a P / NiO heterostructure nanosheet gas-sensitive material; Figure 2 (a) Ni of Example 6 2 P / Ni1 2 P5 heterostructure, (b) Ni of Example 1 2 P / NiO-4h heterostructure and (c) Ni in Example 2 2 Transmission electron microscopy (TEM) images of P / NiO-16h heterostructure; Figure 3 (a) Ni of Example 6 2 P / Ni1 2 P5 heterostructure, (b) Ni of Example 1 2 P / NiO-4h heterostructure and (c) Ni in Example 2 2 High-resolution TEM (HRTEM) image of P / NiO-16h heterostructure; Figure 4 Gas sensitivity tests of samples prepared for Example 1, Example 2 and Example 6: (a) Example 1 was exposed to 5 ppm H at different temperatures. 2The response-recovery curve when S gas is present, (b) is the gas sensing performance exhibited by Example 1, Example 2 and Example 6 at a temperature of 150°C; Figure 5 Preparation of Ni for Example 1 2 (a) Short-term response recovery and (b) long-term sensitivity stability test diagram of P / NiO-4h heterostructure; Figure 6 Ni prepared in Example 1 and Example 2 2 P / NiO heterostructure nanosheets for different gases H 2 S. NH 3 And CO gas sensitivity response curve test. A Ni 2 The method for preparing a P / NiO heterostructure nanosheet gas-sensitive material comprises the following steps: S1. Dispersing the BP nanosheets obtained in advance in 1-methyl-2-pyrrolidone, which is referred to as dispersion A; dispersing a certain amount of metal salt in 1-methyl-2-pyrrolidone, which is referred to as dispersion C; mixing dispersions A and C and stirring them evenly to obtain a reaction precursor; S2. Place the precursor mixture in a flask and place it in an experimental microwave oven under the protection of an argon atmosphere. Heat the reaction with microwaves for a period of time. Wash the reactants with ethanol by centrifugation to obtain the in-situ topologically transformed Ni 2 P / NiO heterostructure nanosheets; S3, the intermediate product Ni 2 P / NiO heterostructure nanosheets were placed in an air furnace for high-temperature calcination, and then oxidized to obtain in-situ transformed Ni 2 P / NiO heterostructure nanosheets.

[0021] The dispersion A in S1 is prepared by dispersing 20 mg of BP nanosheets in 20 mL of 1-methyl-2-pyrrolidone.

[0022] The dispersion C in S2, wherein the metal salt is NiCl2·6H 2 O, 2.6146 g NiCl2·6H2O dispersed in 10 mL 1-methyl-2-pyrrolidone 2 O metal salts.

[0023] The microwave heating power in S2 is 800 W, and the reaction time is 10 min.

[0024] In S3, the calcination temperature in the air furnace is 650° C., and the calcination time is selected in the range of 0 to 16 hours.

[0025] The metal salt in S1 further comprises a phosphorus source-related metal salt, wherein the phosphorus source-related metal salt is selected from at least one of sodium phosphate, potassium phosphate, and sodium phosphite, and is used to control the phosphorus content in the product, thereby optimizing Ni 2Gas sensing properties of P / NiO heterostructure nanosheets.

[0026] The air humidity in the S3 air furnace is controlled within a specified range to prevent water vapor from adversely affecting the high-temperature calcination process and product structure.

[0027] A Ni 2 Application of P / NiO heterostructure nanosheet gas sensing materials, using the Ni 2 Preparation method of P / NiO heterostructure nanosheet gas sensing material 2 P / NiO heterostructure nanosheet gas sensing material, the Ni 2 P / NiO heterostructure nanosheets as gas-sensitive materials for detecting H 2 S.

[0028] Embodiment 1 S1. Prepare the reactant mixture 10 mg of BP nanosheets (based on the two-dimensional nanosheet BP obtained in previous studies) was dispersed in 20 mL of 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixture was recorded as A. 2.6146 g of NiCl 2 6H 2 The metal salt was dispersed in 10 mL 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixed solution was recorded as C. The mixed solution C was slowly injected into the mixed solution A and stirred evenly to obtain a reactant mixed solution.

[0029] S2. Preparation of precursors The mixed solution was transferred to a 50 mL flask, and a reaction device was built under argon atmosphere protection, and then placed in an experimental microwave oven. The experimental conditions set the microwave reaction power to 800 W and the reaction time to 10 min. No stirring was performed during the reaction. The reaction mixture was centrifuged and washed with ethanol, and then dried in a vacuum drying oven at 60 ° C for 12 h to finally obtain the precursor Ni 2 P / Ni 12 P 5 Heterogeneous structure.

[0030] S3, high temperature oxidation The Ni 2 P / Ni 12 P 5 The heterogeneous structure precursor powder was placed in an air furnace. The air furnace was set to heat up at a rate of 5°C / min, heated to 650°C and kept at that temperature for 4 hours, and then cooled naturally to room temperature. The sample was taken out and the powder was recorded as Ni 2 P / NiO-4h.

[0031] Embodiment 2 S1. Prepare the reactant mixture 10 mg of BP nanosheets (based on the two-dimensional nanosheet BP obtained in previous studies) was dispersed in 20 mL of 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixture was recorded as A. 2.6146 g of NiCl 2 6H 2 The metal salt was dispersed in 10 mL 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixed solution was recorded as C. The mixed solution C was slowly injected into the mixed solution A and stirred evenly to obtain a reactant mixed solution.

[0032] S2. Preparation of precursors The mixed solution was transferred to a 50 mL flask, and a reaction device was built under argon atmosphere protection, and then placed in an experimental microwave oven. The experimental conditions set the microwave reaction power to 800 W and the reaction time to 10 min. No stirring was performed during the reaction. The reaction mixture was centrifuged and washed with ethanol, and then dried in a vacuum drying oven at 60 ° C for 12 h to finally obtain the precursor Ni 2 P / Ni 12 P 5 Heterogeneous structure.

[0033] S3, high temperature oxidation The Ni 2 P / Ni 12 P 5 The heterogeneous structure precursor powder was placed in an air furnace. The air furnace was set to heat up at a rate of 5°C / min, heated to 650°C and kept for 16 hours, and then cooled naturally to room temperature. The sample was taken out and the powder was recorded as Ni 2 P / NiO-16h.

[0034] Embodiment 3 S1. Prepare the reactant mixture 10 mg of BP nanosheets (based on the two-dimensional nanosheet BP obtained in previous studies) was dispersed in 20 mL of 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixture was recorded as A. 2.6146 g of NiCl 2 6H 2 The metal salt was dispersed in 10 mL 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixed solution was recorded as C. The mixed solution C was slowly injected into the mixed solution A and stirred evenly to obtain a reactant mixed solution.

[0035] S2. Preparation of precursors The mixed solution was transferred to a 50 mL flask, and a reaction device was built under argon atmosphere protection, and then placed in an experimental microwave oven. The experimental conditions set the microwave reaction power to 800 W and the reaction time to 10 min. Stirring was added halfway. The reaction mixture was centrifuged and washed with ethanol, and then dried in a vacuum drying oven at 60 ° C for 12 h to finally obtain the precursor Ni 2 P / Ni 12 P 5 Heterogeneous structure.

[0036] S3, high temperature oxidation The Ni 2 P / Ni 12 P 5 The heterogeneous structure precursor powder was placed in an air furnace. The air furnace was set to heat up at a rate of 5°C / min, heated to 650°C and kept for 4 hours, and then naturally cooled to room temperature with the furnace to obtain the final agglomerated Ni 2 P / NiO powder.

[0037] Embodiment 4 S1. Prepare the reactant mixture 10 mg of BP nanosheets (based on the two-dimensional nanosheet BP obtained in previous studies) was dispersed in 20 mL of 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixture was recorded as A. 2.6146 g of NiCl 2 6H 2 The metal salt was dispersed in 10 mL 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixed solution was recorded as C. The mixed solution C was slowly injected into the mixed solution A and stirred evenly to obtain a reactant mixed solution.

[0038] S2. Preparation of precursors The mixed solution was transferred to a 50 mL flask, and a reaction device was built under argon atmosphere protection, and then placed in an experimental microwave oven. The experimental conditions set the microwave reaction power to 800 W and the reaction time to 10 min. No stirring was performed during the reaction. The reaction mixture was centrifuged and washed with ethanol, and then dried in a vacuum drying oven at 60 ° C for 12 h to finally obtain the precursor Ni 2 P / Ni 12 P 5 Heterogeneous structure.

[0039] S3, high temperature oxidation The Ni 2 P / Ni 12 P 5 The heterogeneous structure precursor powder was placed in an air furnace. The air furnace was set to heat up at a rate of 5°C / min, heated to 450°C and kept for 4 hours, and then naturally cooled to room temperature with the furnace to obtain the final Ni2 P / NiO powder.

[0040] Embodiment 5 S1. Prepare the reactant mixture 10 mg of BP nanosheets (based on the two-dimensional nanosheet BP obtained in previous studies) was dispersed in 20 mL of 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixture was recorded as A. 2.6146 g of NiCl 2 6H 2 The metal salt was dispersed in 10 mL 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixed solution was recorded as C. The mixed solution C was slowly injected into the mixed solution A and stirred evenly to obtain a reactant mixed solution.

[0041] S2. Preparation of precursors The mixed solution was transferred to a 50 mL flask, and a reaction device was built under argon atmosphere protection, and then placed in an experimental microwave oven. The experimental conditions set the microwave reaction power to 800 W and the reaction time to 10 min. No stirring was performed during the reaction. The reaction mixture was centrifuged and washed with ethanol, and then dried in a vacuum drying oven at 60 ° C for 12 h to finally obtain the precursor Ni 2 P / Ni 12 P 5 Heterogeneous structure.

[0042] S3, high temperature oxidation The Ni 2 P / Ni 12 P 5 The heterogeneous structure precursor powder was placed in an air furnace. The air furnace was set to heat up at a rate of 5°C / min, heated to 550°C and kept for 4 hours, and then naturally cooled to room temperature with the furnace to obtain the final Ni 2 P / NiO powder.

[0043] Embodiment 6 S1. Prepare the reactant mixture 10 mg of BP nanosheets (based on the two-dimensional nanosheet BP obtained in previous studies) was dispersed in 20 mL of 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixture was recorded as A. 2.6146 g of NiCl 2 6H 2 The metal salt was dispersed in 10 mL 1-methyl-2-pyrrolidone and stirred for 30 min. The resulting mixed solution was recorded as C. The mixed solution C was slowly injected into the mixed solution A and stirred evenly to obtain a reactant mixed solution.

[0044] S2. Preparation of precursors The mixed solution was transferred to a 50 mL flask, and a reaction device was built under argon atmosphere protection, and then placed in an experimental microwave oven. The experimental conditions set the microwave reaction power to 800 W and the reaction time to 10 min. No stirring was performed during the reaction. The reaction mixture was centrifuged and washed with ethanol, and then dried in a vacuum drying oven at 60 ° C for 12 h to finally obtain powdered Ni. 2 P / Ni 12 P 5 Heterogeneous structure.

[0045] The samples prepared in Example 1 were characterized and tested, and the results were as follows: See also Figure 1 , Figure 1 Ni of Example 1, Example 2 and Example 6 2 P / NiO-4h、Ni 2 P / NiO-16h and Ni 2 P / Ni 12 P 5 XRD characterization of the precursor. The results show that the phase structure of the precursor corresponds to Ni 2 P and Ni 12 P 5 The sample after high temperature oxidation corresponds to Ni 2 P and NiO two phases, while Ni 12 P 5 The substance disappears. And the extension of high temperature oxidation time leads to Ni 2 The characteristic peak of P almost disappears, the material content is extremely low, and the main phase is NiO.

[0046] See also Figure 2 , Figure 2 (a) is Ni of Example 6 2 P / Ni 12 P 5 The TEM image of the heterogeneous structure shows a two-dimensional layered structure with a rough surface and many micropores. Figure 2 (b) is the partially oxidized Ni of Example 1 2 TEM image of the P / NiO-4h heterostructure shows that the structure has not collapsed, the two-dimensional morphology of the precursor is retained, and a large number of microporous structures still exist on the surface. Figure 2 (c) is the nearly completely oxidized Ni of Example 2 2 TEM image of P / NiO-16h nanoparticle heterojunction.

[0047] See also Figure 3 , Figure 3 (a) is Ni of Example 6 2 P / Ni 12 P 5High-resolution TEM image of the heterostructure. The lattice spacing is measured and it is known that 0.222nm corresponds to Ni 2 P (111) crystal plane, 0.253nm corresponds to Ni 12 P 5 The (002) crystal plane and the existence of a clear interface indicate that Ni 2 P / Ni 12 P 5 Heterostructure formation. Figure 3 (b) is Ni of Example 1 2 High-resolution TEM image of the P / NiO-4h heterostructure. It can be clearly seen at high resolution that multiple local patches are distributed on the Ni 2 On the P substrate, the (200) crystal plane corresponding to NiO is distributed on the Ni 2 A heterostructure is formed on the (111) crystal plane of P. Figure 3 (c) is Ni of Example 2 2 The high-resolution TEM image of the P / NiO-16h heterostructure reveals a large area of ​​0.209 nm lattice fringe spacing, corresponding to the (200) crystal plane of NiO, indicating that NiO is almost completely oxidized to form NiO. 2 The P content is very low.

[0048] See also Figure 4 , Figure 4 Gas sensitivity test of samples prepared for Example 1, Example 2 and Example 6; Figure 4 (a) is Ni 2 P / NiO-4h heterostructures exposed to 5 ppm H at different temperatures 2 The response-recovery curve of the sample under 150℃ H 2 S gas has the highest sensitivity. Figure 4 (b) Ni 2 P / NiO-4h heterostructure and Ni 2 P / Ni 12 P 5 and Ni 2 The gas sensing performance of P / NiO-16h at 150℃ shows that Ni 2 The P / NiO-4h heterostructure surface has the shortest response time and recovery time, and has better H 2 S Gas sensitivity.

[0049] See also Figure 5 , Figure 5 Preparation of Ni for Example 1 2 Short-term response recovery and long-term sensitivity stability test diagram of P / NiO-4h heterostructure. Figure 5 (a) is Ni2 The short-term response recovery curve of P / NiO-4h heterostructure shows that 2 Under the conditions of S gas concentration of 5ppm and working temperature of 150℃, after multiple adsorption and desorption gas-sensitive tests, Ni 2 The gas sensitivity and response time of the P / NiO-4h heterostructure did not change significantly, indicating good response and response stability. Figure 5 (b) Ni 2 The long-term response sensitivity test curve of the P / NiO-4h heterostructure shows that the gas-sensitive response value fluctuates in about 2-3 weeks, and the response value shows a downward trend as the number of days increases. Due to its long-term exposure, the gas-sensitive performance will decay, but it has a high long-term stability overall.

[0050] See also Figure 6 , Figure 6 Ni prepared in Example 1 and Example 2 2 P / NiO heterostructure nanosheets for different gases H 2 S. NH 3 And CO gas sensitivity response curve test. Figure 6 (a) is Ni of Example 2 2 The sensitivity response curves of P / NiO-16h heterostructure nanosheets to different gases show that the sample has extremely low response values ​​to all three gases, and there is almost no difference between the three gases. Figure 6 (b) is Ni of Example 1 2 The sensitivity response curves of P / NiO-4h heterostructure nanosheets to different gases show that the sample is sensitive to H 2 S gas has a higher sensitivity response, which is much higher than NH 3 and CO gas response values, indicating that the high concentration of heterogeneous Ni 2 P / NiO-4h 2D nanosheets for H 2 S gas has a special gas sensitive selectivity. Therefore, Ni 2 P / NiO heterostructure materials have the advantages of preventing H 2 S is a special value for gas leakage prevention.

[0051] Compared with the related art, the present invention provides a Ni 2 The preparation method of P / NiO heterostructure nanosheet gas-sensitive material has the following beneficial effects: The present invention provides a Ni 2 The preparation method of P / NiO heterogeneous structure nanosheet gas-sensitive material adopts a two-step method of microwave in-situ topological transformation and high-temperature oxidation to obtain it, retaining the original two-dimensional nanosheet morphology of BP and transforming it into Ni 2P / NiO heterostructure nanosheets make it suitable for H 2 The gas sensitivity of S is greatly improved.

[0052] The excessive amount of Ni metal source used in S1 of the present invention is to meet the basic requirements of in-situ topological transformation. 2 6H 2 O solution, the Ni source can be continuously provided to the reaction, resulting in Ni 2 P / NiO basically retains the original two-dimensional morphology of BP. And due to undersaturation, some BP and Ni sources are not fully combined, and many micropore defects are generated on the surface of the heterostructure. The above two points are beneficial to the contact between gas and device and gas conduction in the process of gas sensitive detection. On the other hand, the high temperature calcination method with Ni 2 P / NiO heterostructure as a precursor, the obtained Ni 2 P / NiO retains the original two-dimensional morphology and forms Ni 2 P-modified Ni 2 The P / NiO heterostructure has an adjustable electronic structure and is conducive to providing higher carrier mobility. It can play a synergistic role in enabling the heterostructure material to exhibit excellent gas sensitive sensing performance.

[0053] The Ni of the present invention 2 P / NiO heterostructured nanosheets present a thinner two-dimensional nanosheet morphology with high surface exposure, which can provide more adsorption and desorption sites for the target gas, thus having high response sensitivity. 2 The nn heterostructure formed between P and NiO produces an adjustable electronic state, which makes the material body conducive to the adsorption and desorption response of specific gases.

[0054] The Ni of the present invention 2 P / NiO heterostructure nanosheets for assembling gas sensitive sensors for H 2 S gas detection, with ppm level H 2 S gas response, the response is rapid, and the recovery time is short, which shows that the Ni 2 P / NiO heterostructure nanosheets have excellent H 2 S gas sensing sensitivity. In addition, after long-term sensitivity stability testing, the Ni 2 P / NiO heterostructured nanosheets have a durability of up to 5 weeks without obvious attenuation. In order to further evaluate the heterostructured nanosheets for H 2 High selectivity of S gas, introduction of NH 3 and CO as a control gas, the results show that the Ni 2P / NiO heterostructure nanosheets have extremely high sensitivity to H2S and are suitable for preventing H2S in industry. 2 S is a special value for gas leakage prevention.

[0055] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a Ni2P / NiO heterostructure nanosheet gas-sensitive material, characterized in that: The following steps are involved: S1. Dispersing the BP nanosheets obtained in advance in 1-methyl-2-pyrrolidone, which is referred to as dispersion A; dispersing a certain amount of metal salt in 1-methyl-2-pyrrolidone, which is referred to as dispersion C; mixing dispersions A and C and stirring them evenly to obtain a reaction precursor; S2, placing the precursor mixture in a flask, and placing it in an experimental microwave oven under the protection of an argon atmosphere, heating the mixture with microwaves for a period of time, and washing the reactants by centrifugation with ethanol to obtain in-situ topologically transformed Ni2P / NiO heterostructure nanosheets; S3. The obtained intermediate product Ni2P / NiO heterostructure nanosheets are placed in an air furnace for high-temperature calcination, and after oxidation, in-situ transformed Ni2P / NiO heterostructure nanosheets are obtained.

2. The method for preparing the Ni2P / NiO heterostructure nanosheet gas-sensitive material according to claim 1, characterized in that: The dispersion A in S1 is prepared by dispersing 20 mg of BP nanosheets in 20 mL of 1-methyl-2-pyrrolidone.

3. The method for preparing the Ni2P / NiO heterostructure nanosheet gas-sensitive material according to claim 1, characterized in that: The metal salt in the dispersion C in S2 is NiCl2·6H2O, wherein 2.6146 g of NiCl2·6H2O metal salt is dispersed in every 10 mL of 1-methyl-2-pyrrolidone.

4. The method for preparing the Ni2P / NiO heterostructure nanosheet gas-sensitive material according to claim 1, characterized in that: The microwave heating power in S2 is 800 W, and the reaction time is 10 min.

5. The method for preparing the Ni2P / NiO heterostructure nanosheet gas-sensitive material according to claim 1, characterized in that: In S3, the calcination temperature in the air furnace is 650° C., and the calcination time is selected in the range of 0 to 16 hours.

6. The method for preparing the Ni2P / NiO heterostructure nanosheet gas-sensitive material according to claim 1, characterized in that: The metal salt in S1 also includes a phosphorus source-related metal salt, and the phosphorus source-related metal salt is selected from at least one of sodium phosphate, potassium phosphate, and sodium phosphite, which is used to regulate the phosphorus content in the product, thereby optimizing the gas sensing performance of the Ni2P / NiO heterostructure nanosheets.

7. The method for preparing the Ni2P / NiO heterostructure nanosheet gas-sensitive material according to claim 1, characterized in that: The air humidity in the S3 air furnace is controlled within a specified range to prevent water vapor from adversely affecting the high-temperature calcination process and product structure.

8. An application of Ni2P / NiO heterostructure nanosheet gas-sensitive material, characterized in that: A Ni2P / NiO heterostructure nanosheet gas-sensitive material is prepared by the method for preparing a Ni2P / NiO heterostructure nanosheet gas-sensitive material as described in any one of claims 1 to 7, and the Ni2P / NiO heterostructure nanosheet gas-sensitive material is used to detect H2S.

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