A bismuth vanadate material with the function of selectively detecting low concentration hydrogen sulfide gas

Abstract

The application discloses a bismuth vanadate material with the function of selectively detecting low-concentration hydrogen sulfide gas, and application of the bismuth vanadate material as a high-selectivity light-driven sensor for detecting low-concentration hydrogen sulfide gas, and belongs to the technical field of material preparation and gas-sensitive sensing. The bismuth vanadate material is obtained through homogeneous precipitation by adjusting the pH of a precursor solution to control the growth of a bismuth vanadate crystal face. The simple and easy-to-synthesize bismuth vanadate octahedron can effectively sense low-concentration hydrogen sulfide under light driving, and has a high response value, good selectivity, long-term stability and a low detection limit. The application has the advantages of simple process, low cost, large-scale production, actual production needs, and great application potential.

Description

Technical Field

[0001] This invention belongs to the field of material preparation and gas sensing technology, specifically relating to a method for preparing and applying bismuth vanadate material with selective detection function for low concentration hydrogen sulfide gas by homogeneous precipitation. Background Technology

[0002] Detecting low concentrations of hydrogen sulfide in the environment is of great significance to both ecosystems and human health. Among the many chemical sensing methods used to achieve a response to hydrogen sulfide, photoactivated sensing is considered a low-cost and portable strategy at room temperature. However, some metal-oxide-semiconductor (MOS) semiconductors have been photoactivated to operate at ambient temperatures, but it is difficult to maintain good sensing performance. Crystal facet engineering is one of the most effective strategies to improve gas sensing performance because some crystal faces have high surface energy and abundant low-coordination atoms, which can simultaneously promote the migration of photogenerated carriers and the adsorption of target gases. We have noticed that bismuth vanadate is an ideal photoactivated material, which not only responds to visible light but also has manipulable crystal faces at the atomic level. Currently, relevant studies have reported bismuth vanadate with various morphologies and exposed crystal faces, such as tetradodecahedrons exposing (110) and (010) and teicohedrons exposing (132), (321), and (121) crystal faces. However, there is no application of octadecahedral bismuth vanadate with exposed (111) crystal faces and controlled crystal facet ratios through crystal facet engineering to gas sensors. Summary of the Invention

[0003] The purpose of this invention is to provide a functional gas-sensitive material for selectively detecting low concentrations of hydrogen sulfide gas, its preparation method, and its applications. The bismuth vanadate material prepared by this invention can efficiently achieve rapid response to low concentrations of hydrogen sulfide gas, and exhibits good selectivity and lifespan. This invention features a simple process, low cost, and high efficiency, meeting practical production needs and showing great application potential.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A bismuth vanadate material with selective detection of low concentration hydrogen sulfide gas is a monoclinic bismuth vanadate material with a smooth octahedral morphology, exposing 4 (110), 4 (011), 2 (010) and 8 (111) crystal planes, which can achieve efficient separation of photogenerated carriers and characteristic adsorption of hydrogen sulfide gas.

[0006] The bismuth vanadate material is prepared by a simple homogeneous precipitation method, using bismuth nitrate and ammonium metavanadate as precursors. By adjusting the pH, an octahedral bismuth vanadate sensor material with high selectivity for detecting low concentrations of hydrogen sulfide gas with light-driven response is prepared.

[0007] The specific preparation method includes the following steps:

[0008] 1) Dissolve 12 mmol bismuth nitrate and 12 mmol ammonium metavanadate in 50 mL of 2 M nitric acid solution respectively. Mix the two solutions thoroughly and add 5 g of urea. Stir and heat to 90°C.

[0009] 2) Stir the mixture obtained in step 1) at 90°C for 24 hours.

[0010] 3) After cooling the mixture obtained in step 2) to room temperature, centrifuge it and wash it several times with distilled water and ethanol;

[0011] 4) Dry the solid obtained in step 3) at 80°C for 8 hours to obtain the octadecahedral bismuth vanadate material.

[0012] Application: The bismuth vanadate material described above is used in the preparation of light-driven sensors for low-concentration hydrogen sulfide gas, which can detect hydrogen sulfide content at the ppb level in the gas.

[0013] The significant advantages of this invention are:

[0014] (1) This invention provides a method for preparing functionalized bismuth vanadate materials by homogeneous precipitation, which regulates the growth of bismuth vanadate crystal faces by adjusting the pH of the precursor solution, and prepares hydrogen sulfide gas-sensitive materials by utilizing the separation and adsorption characteristics of photogenerated carriers on the crystal faces.

[0015] (2) The octahedral bismuth vanadate material can efficiently detect low concentrations of hydrogen sulfide gas under light irradiation, and has high selectivity and good stability.

[0016] (3) The entire process of the present invention is simple and easy to control, with low energy consumption, high yield and low cost, which meets the actual production needs and is conducive to large-scale promotion. Attached Figure Description

[0017] Figure 1 The X-ray diffraction pattern of the octahedral bismuth vanadate material obtained in Example 1 shows that the prepared product corresponds to monoclinic scheelite of bismuth vanadate.

[0018] Figure 2 , Figure 3 The images shown are scanning electron microscope (SEM) images and transmission electron microscope (TEM) images of the octahedral bismuth vanadate material obtained in Example 1. Figure 2 This indicates that the prepared product has an octahedral morphology. Figure 3 The lattice fringes indicate that the prepared product belongs to monoclinic scheelite.

[0019] Figure 4 This is a comparison graph of the response values ​​of Example 1 to different types of gases at 100 ppm. The graph shows that the prepared material exhibits high selectivity for hydrogen sulfide.

[0020] Figure 5 The figure shows the response current of Example 1 to 100 ppm hydrogen sulfide under dark and light conditions. It can be seen from the figure that the response value of the prepared material increases and the response recovery speed accelerates under light illumination.

[0021] Figure 6 7 represents the sensing response performance of 18-octahedral bismuth vanadate to hydrogen sulfide gas under light illumination obtained in Example 1. Figure 6 The graph shows the response current changes of the octahedral bismuth vanadate obtained in Example 1 to different concentrations of hydrogen sulfide gas under illumination. Figure 7 in accordance with Figure 6 The relationship between the obtained response value and the gas concentration, and the fitted linear line, yielded a theoretical detection limit of 12.3 ppb. From the figure, we can see that under illumination conditions, the obtained octahedral bismuth vanadate exhibits a sensitive response and a low detection limit to hydrogen sulfide.

[0022] Figure 8 The figure shows the sensing response of the octadecahedral bismuth vanadate obtained in Example 1 to 12 ppm hydrogen sulfide gas and 12 ppm hydrogen sulfide gas mixed with 20% humid air under light illumination. As can be seen from the figure, the obtained sensing material is not significantly affected by air humidity and can meet the requirements for stable detection of hydrogen sulfide gas under actual conditions.

[0023] Figure 9 The figure shows the response of the octadecahedral bismuth vanadate material obtained in Example 1 to 100 ppm hydrogen sulfide gas under light after 100 days of storage. As can be seen from the figure, the response value decreased slightly after 100 days, but recovered after purging with 20% humid air. This indicates that the obtained sensing material has a stable response and its detection performance can be restored by purging with humid air.

[0024] Figure 10 The images show scanning electron microscope (SEM) images of the bismuth vanadate materials obtained in Examples 2(a), 3(b), and 4(c). As can be seen from the images, when the amount of urea is less than 5 g, the octahedron is not yet formed; when the amount of urea is greater than 5 g, the octahedron structure is broken.

[0025] Figure 11 The graphs show the hydrogen sulfide conversion of the bismuth vanadate materials obtained in Examples 1-4. As can be seen from the graphs, the hydrogen sulfide conversion ability of Examples 1-4 first increases and then decreases with increasing urea content. Therefore, 5 g of urea is the optimal amount. Detailed Implementation

[0026] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0027] Example 1

[0028] 1) Dissolve 12 mmol bismuth nitrate and 12 mmol ammonium metavanadate in 50 mL of 2 M nitric acid solution respectively. Mix the two solutions thoroughly and add 5 g of urea. Stir and heat to 90°C.

[0029] 2) Stir the mixture obtained in step 1) at 90°C for 24 hours.

[0030] 3) After cooling the mixture obtained in step 2) to room temperature, centrifuge it and wash it several times with distilled water and ethanol;

[0031] 4) Dry the solid obtained in step 3) at 80°C for 8 hours to obtain Octa-BiVO4-5.

[0032] The Octa-BiVO4-5 octadecahedron prepared in Example 1 exposes 4 (110), 4 (011), 2 (010), and 8 (111) crystal planes, among which the (111) crystal plane is advantageous for rapid response to hydrogen sulfide gas. The preparation method of the present invention can obtain octadecahedral bismuth vanadate with exposed (111) crystal planes.

[0033] Example 2

[0034] 1) Dissolve 12 mmol bismuth nitrate and 12 mmol ammonium metavanadate in 50 mL of 2 M nitric acid solution respectively. Mix the two solutions thoroughly and add 4 g of urea. Stir and heat to 90°C.

[0035] 2) Stir the mixture obtained in step 1) at 90°C for 24 hours.

[0036] 3) After cooling the mixture obtained in step 2) to room temperature, centrifuge it and wash it several times with distilled water and ethanol;

[0037] 4) Dry the solid obtained in step 3) at 80°C for 8 hours to obtain Octa-BiVO4-4.

[0038] Example 3

[0039] 1) Dissolve 12 mmol bismuth nitrate and 12 mmol ammonium metavanadate in 50 mL of 2 M nitric acid solution respectively. Mix the two solutions thoroughly and add 6 g of urea. Stir and heat to 90°C.

[0040] 2) Stir the mixture obtained in step 1) at 90°C for 24 hours.

[0041] 3) After cooling the mixture obtained in step 2) to room temperature, centrifuge it and wash it several times with distilled water and ethanol;

[0042] 4) Dry the solid obtained in step 3) at 80°C for 8 hours to obtain Octa-BiVO4-6.

[0043] Example 4

[0044] 1) Dissolve 12 mmol bismuth nitrate and 12 mmol ammonium metavanadate in 50 mL of 2 M nitric acid solution respectively. Mix the two solutions thoroughly and add 8 g of urea. Stir and heat to 90°C.

[0045] 2) Stir the mixture obtained in step 1) at 90°C for 24 hours.

[0046] 3) After cooling the mixture obtained in step 2) to room temperature, centrifuge it and wash it several times with distilled water and ethanol;

[0047] 4) Dry the solid obtained in step 3) at 80°C for 8 hours to obtain Octa-BiVO4-8.

[0048] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. The application of a bismuth vanadate material in the preparation of a room-temperature optically driven sensor with low concentration hydrogen sulfide gas, characterized in that: The bismuth vanadate material is a smooth octahedron, belonging to the monoclinic phase bismuth vanadate, with 4 (110), 4 (011), 2 (010) and 8 (111) crystal planes exposed. It can detect low concentrations of hydrogen sulfide gas with high selectivity under room temperature light-driven conditions, with a theoretical detection limit of 12.3 ppb.

2. The application according to claim 1, characterized in that: The preparation method of the bismuth vanadate material includes the following steps: 1) Dissolve 12 mmol bismuth nitrate and 12 mmol ammonium metavanadate in 50 mL of 2 M nitric acid solution respectively. Mix the two solutions thoroughly and add 5 g of urea. Stir and heat to 90°C. 2) Stir the mixture obtained in step 1) at 90°C for 24 hours. 3) After cooling the mixture obtained in step 2) to room temperature, centrifuge it and wash it several times with distilled water and ethanol; 4) Dry the solid obtained in step 3) at 80°C for 8 hours to obtain the octadecahedral bismuth vanadate material.

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