A semiconductor gas-sensitive material co-doped with S and N, SnO2, its preparation method and application
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNIV OF ELECTRONICS SCI & TECH OF CHINA
- Filing Date
- 2026-05-27
- Publication Date
- 2026-07-21
Smart Images
Figure CN122282882B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to, but is not limited to, the field of novel functional materials technology, and particularly relates to a semiconductor gas-sensitive material co-doped with S and N, SnO2, its preparation method, and its application. Background Technology
[0002] With the development of industries such as petrochemicals, natural gas extraction and storage, wastewater treatment, papermaking, and metallurgy, the demand for leak monitoring and early warning of hydrogen sulfide (H2S), a highly toxic and corrosive hazardous gas with the characteristics of being odorous at low concentrations but causing olfactory paralysis at high concentrations, continues to increase. H2S can damage the human respiratory and nervous systems even at extremely low concentrations, and may cause poisoning in confined spaces, equipment corrosion, and secondary safety accidents. Therefore, developing sensing materials and devices capable of rapidly, stably, and selectively identifying H2S at low concentrations in complex background gases (humidity fluctuations, VOCs, CO, NH3, SO2, etc.) has significant value for public safety and industrial applications.
[0003] Metal oxide semiconductor gas-sensitive materials are widely used due to their low cost, ease of integration, and fast response speed. Among them, SnO2 has advantages such as good chemical stability, high electron mobility, and mature processing, making it a typical gas-sensitive substrate. However, traditional SnO2 is generally sensitive to a variety of reducing gases, resulting in problems such as insufficient selectivity, high operating temperature, significant humidity interference, and long-term drift. In particular, it is easily affected by coexisting gases such as ethanol, acetone, and CO in H2S detection, and the instability of surface-adsorbed oxygen species and defect states leads to decreased signal repeatability. Existing improvement strategies, such as noble metal catalysis and heterojunction composites, can improve the response, but they often face limitations such as high cost, insufficient resistance to poisoning, poor interface reconstruction, and poor batch consistency, making it difficult to balance sensitivity, selectivity, and manufacturability.
[0004] Anion doping provides a more tunable pathway to enhance the gas-sensitive selectivity of SnO2. N and S doping can modulate the band structure and surface electron density without significantly disrupting the host crystal phase, promoting the formation and stabilization of defects such as oxygen vacancies, altering the generation / migration and electron transfer channels of chemisorbed oxygen, thereby lowering the gas reaction energy barrier and enhancing low-temperature response. Particularly for H2S, S and N co-doping is expected to synergistically regulate surface acidity / basicity and defect chemistry, constructing sites more suited to H2S adsorption-activation, improving preferential adsorption / rapid reaction to hydrogen sulfide, and suppressing non-selective responses to common interfering gases. Furthermore, co-doping may improve the surface stability of materials under high humidity environments, enhancing long-term consistency and reliability.
[0005] However, existing methods for preparing S / N-doped SnO2 still suffer from problems such as low dopant source utilization, difficulty in controlling dopant content and spatial distribution, easy particle sintering leading to a decrease in specific surface area, and insufficient scalability and reproducibility, which limit its widespread application in industrial-grade H2S monitoring. Therefore, it is necessary to propose a simple, controllable, and easily scalable S / N co-doped SnO2 semiconductor gas-sensitive material and its preparation method to achieve high selectivity, low detection limit, and rapid response / recovery for H2S, and further expand its application in petrochemical safety, pipeline monitoring, mine and wastewater treatment scenarios. Summary of the Invention
[0006] The purpose of this invention is to provide a semiconductor gas-sensitive material, preparation method and application of S / N co-doped SnO2, in order to solve the technical problems of low doping source utilization, difficulty in controlling doping content and spatial distribution, easy sintering of particles leading to a decrease in specific surface area and insufficient scalability and repeatability in the preparation methods of S / N doped SnO2 in the prior art.
[0007] To solve the above-mentioned technical problems, the specific technical solution of the present invention is as follows:
[0008] A method for preparing an S, N co-doped SnO2 semiconductor gas-sensitive material, the method comprising the following steps:
[0009] Step S01: Dissolve SnCl4·5H2O in deionized water, add hydrochloric acid to adjust the pH of the solution, and obtain tin source solution A;
[0010] Step S02: Add thiourea, CTAB and compound additives to tin source solution A, stir evenly to obtain precursor solution, transfer precursor solution to reaction vessel, react in hydrothermal at 120-200℃ for 6-20 h to obtain hydrothermal product;
[0011] Step S03: After washing and drying the hydrothermal product, impregnate it a second time with thiourea solution, filter it out and dry it. The S / N-SnO2 semiconductor gas-sensitive material is obtained by two-stage calcination treatment.
[0012] Furthermore, in step S1, the hydrochloric acid concentration is 0.05–0.5 mol / L, and the target pH is 1–3.
[0013] Furthermore, in step S02, the molar ratio of SnCl4·5H2O to thiourea is 1:(0.1–10), and the amount of CTAB added is 0.1–10 g / L.
[0014] Further, in step S02, the compound additive consists of one or more of citric acid, NH4F, NaF, urea, and EDTA, and the amount added is 0.05–0.5 times the molar amount of Sn.
[0015] Further, in step S03, the concentration of the thiourea solution is 0.01–0.1 mol / L, and the immersion time is 1–15 min.
[0016] Furthermore, in the two-stage calcination of step S03, the first stage is an inert stage, which is calcined at 250-350℃ for 0.5-2 h in an N2 or Ar atmosphere, and the second stage is a re-oxidation stage, which is calcined at 400-650℃ for 1-4 h in an air atmosphere.
[0017] This invention also proposes an S / N co-doped SnO2 semiconductor gas-sensitive material, which is prepared by the above-described preparation method. The semiconductor gas-sensitive material is an S / N-SnO2 semiconductor gas-sensitive material, in which SnO2 is the main crystal phase, and S and N are introduced into the SnO2 lattice or near the surface and defect sites to form an asymmetric structural unit of Sn–S–Sn–O–Sn–N.
[0018] Furthermore, the Sn–S–Sn–O–Sn–N asymmetric structural unit simultaneously provides sulfur affinity anchor sites and polar / basic hydrogen accepting sites, which together constitute asymmetric sites.
[0019] The present invention also proposes an application of an S, N co-doped SnO2 semiconductor gas-sensitive material, which is ground and then coated or deposited on a substrate with electrodes to form a resistive gas-sensitive element for selective detection of H2S.
[0020] Compared with the prior art, the present invention has the following beneficial technical effects:
[0021] 1) This invention proposes S and N co-doping of SnO2 to form an asymmetric Sn–S–Sn–O–Sn–N structural unit, which is significantly different from existing technologies in terms of technical concept. On the one hand, it not only limits the doping elements to S and N, but also further limits their cooperative distribution relationship in the SnO2 lattice or near-surface defect sites, thus distinguishing it from the random doping or simple substitutional doping methods in existing technologies. On the other hand, by constructing asymmetric structural units, the composite bonding form and its spatial distribution characteristics are clearly defined at the microscopic level, breaking through the traditional approach of relying solely on oxygen vacancies or lattice distortion to regulate performance. Although existing literature involves defect modulation caused by doping, it has not revealed or inspired asymmetric composite structures with directionality and uneven charge distribution. This invention can form active centers with uneven charge distribution on the SnO2 surface, thereby enhancing the directional adsorption and charge transfer efficiency of gas molecules, while realizing the synergistic utilization of n-type and p-type regulation mechanisms, which is beneficial to improving the selectivity and response stability of gas-sensitive materials. Existing single-doping or simple co-doping schemes mainly rely on increasing the number of defects to improve sensitivity, making it difficult to achieve fine-grained control over the interface reaction pathway and selectivity. Therefore, this invention is significantly different and innovative in both its structural construction method and the resulting performance control mechanism.
[0022] 2) Ultra-high selectivity H2S detection of this invention: To address the problems of traditional SnO2 sensing materials being generally sensitive to reducing gases, having poor H2S selectivity, weak signals at low concentrations, and being easily interfered with, this invention utilizes S and N co-source doping and structure-directed processes provided by thiourea to form Sn–S–Sn–O–Sn–N asymmetric structural units in situ near the surface of SnO2. This asymmetric structure generates polarization defects and uneven electron distribution within a localized area, synergistically providing sulfur affinity anchoring sites and polar / basic hydrogen accepting sites, making it easier for H2S to undergo directional adsorption, partial dissociation, and significant charge transfer. This allows for the acquisition of a specific H2S sensing signal at room temperature and effectively suppresses the non-selective responses of common interfering gases such as ethanol, acetone, CO, and NH3.
[0023] 3) This invention exhibits enhanced resistance to moisture and poisoning: Addressing the issues of signal attenuation caused by water film coverage of SnO2 in high-humidity environments and passivation and drift caused by surface sulfidation induced by H2S, this invention stabilizes the surface-active adsorption state and optimizes the electron transport channel through S and N co-doping-induced defect chemical regulation, making the sensing reaction more biased towards a reversible adsorption-charge transfer process and reducing the probability of irreversible sulfidation / sulfate accumulation; at the same time, segmented calcination helps remove residual organic matter and stabilize the near-surface doping and defect distribution, thereby improving multi-cycle repeatability and long-term working stability.
[0024] 4) The present invention has a simple preparation method, is scalable, and has low cost: The present invention uses common chemical raw materials such as SnCl4·5H2O, thiourea and CTAB. The process flow is a one-pot hydrothermal reaction combined with subsequent heat treatment, which does not require precious metal loading, complex multi-step coating or high pressure / inert glove box operation; the reaction conditions are mild and have good repeatability, which is convenient for batch preparation and device coating and integration, and has good prospects for engineering and industrial application.
[0025] 5) The S / N co-doped SnO2 gas-sensitive material developed in this invention significantly improves the selective sensing performance for H2S by constructing Sn–S–Sn–O–Sn–N asymmetric defect structural units and optimizing the pore structure in the near-surface layer of SnO2. It exhibits high selectivity, high sensitivity, low detection limit, rapid response / recovery, and good moisture stability, benefiting from sulfur affinity anchoring—specific adsorption at two sites by polar hydrogen, efficient charge transfer induced by localized polarization defects, and controlled surface reaction processes. This material is prepared using a one-pot hydrothermal combined with segmented calcination process of SnCl4·5H2O–thiourea–CTAB, which is simple, uses readily available raw materials, is low-cost, and can be mass-produced and integrated into devices. It can provide a reliable foundation for accurate H2S sensing materials in industrial safety early warning, environmental monitoring, and smart IoT sensing.
[0026] 6) The expected benefits and commercial value of the technical solution of this invention after transformation are as follows:
[0027] This invention relates to an S / N co-doped SnO2 gas-sensitive material using conventional raw materials such as SnCl4·5H2O, thiourea, and CTAB. The controlled construction of doped and defect structures can be achieved through a one-pot hydrothermal combined with segmented calcination. The overall process is short, mild, and highly repeatable, providing a foundation for large-scale preparation and batch consistency. This material can be integrated with MEMS micro-hotplates and microelectrode structures via coating / spraying / printing, facilitating the construction of low-power, highly integrated integrated gas sensing microsystems. This provides key material and process support for portable, rapid, and miniaturized H2S detection equipment.
[0028] 7) The technical solution of this invention fills a technological gap in the industry both domestically and internationally:
[0029] In existing technologies, metal oxide gas-sensitive materials for H2S mostly rely on noble metal catalysis or composite heterojunctions to improve performance. However, they generally suffer from insufficient selectivity, significant humidity interference, and unstable signals at low temperatures / concentrations. Especially under testing conditions that more closely resemble real-world scenarios, such as dynamic gas mixing, there are few publicly reported studies achieving extremely low detection limits and high reliability. This invention proposes a site engineering strategy centered on Sn–S–Sn–O–Sn–N asymmetric defect structural units. This strategy enables the material to achieve a significant response under low-concentration H2S conditions and exhibits stronger suppression of common reducing interfering gases. Simultaneously, it possesses high dynamic response capability and cycling stability, demonstrating the technical potential for practical application under real-world detection conditions.
[0030] 8) The technical solution of this invention solves a technical problem that people have long desired to solve but have never been able to successfully address:
[0031] Metal oxide semiconductor gas-sensitive materials have long been limited by bottlenecks such as the difficulty in simultaneously achieving high sensitivity and high selectivity, susceptibility to humidity and sulfur poisoning, and insufficient repeatability and long-term stability. Traditional improvement methods often focus on enhancing catalytic activity, which can easily introduce a broad spectrum response to multiple reducing gases, thus weakening selectivity. This invention constructs a polarized asymmetric defect structure in the near-surface layer of SnO2 through S / N co-doping, forming a dual-site specific adsorption and charge transfer channel for sulfur affinity anchoring and polar hydrogen acceptance. This allows selectivity to originate from site structure recognition rather than simply reaction intensity, thereby simultaneously improving sensitivity, selectivity, and stability from a mechanistic perspective. This significantly broadens the usable concentration range and accuracy of H2S detection, demonstrating outstanding substantive features and significant progress. Attached Figure Description
[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0033] Figure 1 This is the XRD pattern of the S / N-SnO2 gas-sensitive material synthesized in Example 1 of this invention (XRD is an abbreviation for X-ray diffraction). The preceding number represents the molar ratio of thiourea added. For example, 0.1S-SnO2 means that the molar ratio of SnCl4·5H2O to thiourea is 1:0.1.
[0034] Figure 2This is a microscopic morphology image (TEM image, TEM is an abbreviation for Transmission Electron Microscope) of the S / N-SnO2 composite gas-sensitive material synthesized in Example 1 of the present invention.
[0035] Figure 3 This is the XPS (photoelectron spectroscopy) spectrum of the S / N-SnO2 composite gas-sensitive material synthesized in Example 1 of this invention;
[0036] Figure 4 The different proportions of S / N-SnO2 composite gas-sensitive materials synthesized in Example 1 of this invention are used to detect the response value of 30 ppm H2S gas.
[0037] Figure 5 This is the response diagram of the S / N-SnO2 composite gas-sensitive material synthesized in Example 1 of the present invention in detecting the H2S gas concentration gradient from 3ppb to 50 ppm;
[0038] Figure 6 This is a comparison chart of the S / N-SnO2 composite gas-sensitive material synthesized in Example 1 of this invention when detecting different gases. Detailed Implementation
[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0040] This invention provides a method for preparing an S / N-SnO2 co-doped semiconductor gas-sensitive material, namely an S / N-SnO2 semiconductor gas-sensitive material, the method comprising the following steps:
[0041] Step S01: Dissolve SnCl4·5H2O in deionized water, add hydrochloric acid to adjust the pH of the solution, and obtain tin source solution A.
[0042] Specifically, 0.01 mol of SnCl4·5H2O is dissolved in 80 mL of deionized water, and hydrochloric acid is added to adjust the pH of the solution to obtain tin source solution A. The hydrochloric acid concentration is 0.05–0.5 mol / L, and the target pH is 1–3. Preferably, the hydrochloric acid concentration is 0.05–0.3 mol / L, and the target pH is 1–2.
[0043] Step S02: Add thiourea (CH4N2S), CTAB, and compound additives to tin source solution A, stir evenly to obtain precursor solution, transfer precursor solution to reaction vessel, and react in hydrothermal at 120-200℃ for 6-20 h to obtain hydrothermal product.
[0044] Specifically, the molar ratio of SnCl4·5H2O to thiourea is 1:(0.1–10), preferably 0.1:(1–6).
[0045] CTAB is used to regulate the nano-assembly and mesoporous structure formation of S / N-SnO2 semiconductor gas-sensitive materials, and its addition amount is 0.1–10 g / L (based on the volume of the precursor liquid), preferably 0.5–8 g / L.
[0046] The compound additive consists of one or more of citric acid, NH4F, NaF, urea, and EDTA, and is added at a rate of 0.05–0.5 times the molar amount of Sn. The compound additive functions to react with Sn. 4+ The formation of local coordination complexes with and / or thiourea-derived groups inhibits bulk sulfidation side reactions and ion migration, which is beneficial for the formation of Sn–S and Sn–N adjacent structures in subsequent solid-phase transformation, thereby increasing the probability of the formation of asymmetric structural units.
[0047] Step S03: After washing and drying the hydrothermal product, impregnate it a second time with thiourea solution, filter it out and dry it. The S / N-SnO2 semiconductor gas-sensitive material is obtained by two-stage calcination treatment.
[0048] Specifically, the concentration of the thiourea solution is 0.01–0.1 mol / L, and the impregnation time is 1–15 min; preferably, the concentration of the thiourea solution is 0.02–0.8 mol / L, and the impregnation time is preferably 1–10 min. The purpose of the secondary impregnation is to supplement the near-surface layer with S / N precursors without changing the main crystal phase, so that Sn–S and Sn–N are more likely to solidify in the near-surface layer in an ortho / bridging manner, thereby improving the density and detectability of the Sn–S–Sn–O–Sn–N asymmetric structural units.
[0049] In the two-stage calcination process, the first stage is an inert stage, calcined at 250-350℃ for 0.5-2 h in a N2 or Ar atmosphere, and the second stage is a re-oxidation stage, calcined at 400-650℃ for 1-4 h in an air atmosphere. The inert stage utilizes the thermal decomposition of the compound additives to generate a local reduction and solid-phase reaction environment, promoting the insertion of Sn–S and Sn–N in an ortho / bridging manner to form asymmetric structural units; the re-oxidation stage removes residual carbon and crystallizes and stabilizes SnO2, while retaining the near-surface S and N doping and defect polarization structures.
[0050] In addition, the present invention also provides a semiconductor gas-sensitive material with S and N co-doped SnO2 prepared by the above method, namely S / N-SnO2 semiconductor gas-sensitive material. The S / N-SnO2 semiconductor gas-sensitive material has SnO2 as the main crystal phase, and S and N are introduced into the SnO2 lattice or near-surface defect sites to form an asymmetric structural unit of Sn–S–Sn–O–Sn–N.
[0051] Furthermore, this invention also proposes the application of S / N-SnO2 semiconductor gas-sensitive materials. The S / N-SnO2 semiconductor gas-sensitive materials prepared by the above method are ground and then coated or deposited on a substrate with electrodes to form a resistive gas-sensitive element for selective detection of H2S.
[0052] The working principle of this S / N-SnO2 semiconductor gas-sensitive material is based on a synergistic mechanism of asymmetric sites, charge transfer amplification, and structural mass transfer optimization. The S and N co-doping in the S / N-SnO2 semiconductor gas-sensitive material induces the synergistic existence of oxygen vacancies and surface polarization defects, which facilitates preferential adsorption and charge transfer of the target gas on the Sn–S–Sn–O–Sn–N asymmetric structural units.
[0053] First, the S / N-SnO2 semiconductor gas-sensitive material forms Sn–S–Sn–O–Sn–N asymmetric structural units in the lattice or near-surface layer through thiourea co-source doping. The Sn–S–Sn–O–Sn–N asymmetric structural units simultaneously provide sulfur affinity anchor sites and polar / basic hydrogen accepting sites. The sulfur affinity anchor sites and polar / basic hydrogen accepting sites constitute asymmetric sites, enabling H2S to undergo directional adsorption at the asymmetric sites and more easily undergo partial dissociation and charge transfer, thereby producing a significant change in resistance. Meanwhile, common interfering gases such as ethanol, acetone, CO, and NH3 have weak adsorption configurations and electronic coupling capabilities at these asymmetric sites, thus effectively suppressing the response and achieving selective recognition of H2S. Secondly, the S / N co-doping-induced localized polarization defects and oxygen vacancies synergistically regulate the concentration of adsorbed oxygen species and carriers on the surface, reducing the interfacial reaction barrier and improving electron transport efficiency. This allows the S / N-SnO2 semiconductor gas-sensitive material to maintain high sensitivity and rapid dynamic response even at lower operating temperatures. Finally, CTAB structure-guided nanoassembly and pore control construct more interconnected mesoporous mass transfer channels in the S / N-SnO2 semiconductor gas-sensitive material, shortening the H2S diffusion path and accelerating the adsorption / desorption process. Simultaneously, segmented calcination helps stabilize the near-surface doping and defect distribution, remove residual organic matter, and slow down sulfidation passivation and baseline drift. This enables the S / N-SnO2 semiconductor gas-sensitive material to maintain high and repeatable gas-sensing performance under dynamic gas distribution and long-term exposure conditions.
[0054] Example 1:
[0055] Preparation of S / N-SnO2: 0.01 mol SnCl4·5H2O was dissolved in 80 mL of deionized water; hydrochloric acid (0.1 mol / L) was added to adjust the pH to 2, yielding tin source solution A. Thiourea (Sn:thiourea = 1:0.5), CTAB (5 g / L), and compound additives (citric acid + NH4F, added at 0.2 and 0.1 molar equivalents of Sn, respectively) were added to tin source solution A, and the mixture was stirred for 30 min to obtain a precursor solution. The precursor solution was transferred to a reactor and hydrothermally reacted at 180℃ for 12 h to obtain a hydrothermal product. The hydrothermal product was washed, dried, and then impregnated twice with 0.05 mol / L thiourea solution for 5 min, filtered, and dried. It was calcined in N2 at 300℃ for 1 h, and then calcined in air at 500℃ for 3 h to obtain the S / N-SnO2 semiconductor gas-sensitive material.
[0056] The S / N-SnO2 semiconductor gas-sensitive material synthesized in Example 1 of this invention was characterized, such as... Figure 1 , Figure 2 , Figure 3 The images shown are XRD pattern, TEM image, and XPS image, respectively. Figure 1 The image shows the XRD pattern of the S / N-SnO2 semiconductor gas-sensitive material synthesized in Example 1. Compared with the PDF standard card, the presence of SnO2 can be clearly seen. After modification, the main peak of the XRD shifts to a lower value, indicating that the doping was successfully achieved. Figure 2 This is a TEM image of the S / N-SnO2 semiconductor gas-sensitive material synthesized in Example 1. As can be seen, the lattice spacing of the sample changed after modification, further proving the successful doping. Figure 3 The image shows the XPS plot of the S / N-SnO2 semiconductor gas-sensitive material synthesized in Example 1. It can be seen that S and N peaks were undetectable before doping, but became clearly visible after doping, indicating successful S / N co-doping. This demonstrates the successful construction of the S / N co-doped chemical state.
[0057] H2S gas-sensing performance test: 0.015 g of the synthesized S / N-SnO2 semiconductor gas-sensing material was dissolved in 400 μL of deionized water. The sample was placed in an ultrasonic machine and sonicated for 5 min to disperse it evenly in the water. Then, 2.5 μL of the dispersed sample solution was taken with a pipette and evenly coated onto the electrode plate. After the solution was allowed to air dry naturally, a layer of composite gas-sensing material was coated on the surface of the electrode plate, forming an S / N-SnO2 sensor. The electrode plate was transferred to a heating stage and connected to a resistance monitoring device for H2S detection. The entire monitoring process adopted the dynamic gas mixing principle to simulate the air flow in the environment. The dynamic gas flow rate was 3 L / min, simulating the gas composition of hydrogen sulfide in the air environment, which was a mixture of H2S, N2, and O2, with O2 maintaining a proportion of 20%, i.e., 600 ml / min. First, the heating stage was set to a test temperature of 30°C. Air, 30 ppm H2S gas, and then air were sequentially introduced at a rate of 3 L / min. The resistance changes during gas switching were collected to obtain the response value change curve. The gas-sensing performance of the S / N-SnO2 semiconductor gas-sensitive material synthesized in this invention is as follows: Figure 4-6 As shown. Figure 4 The results show the response values of S / N-SnO2 semiconductor gas-sensitive materials with different doping ratios synthesized in Example 1 for detecting 30 ppm H2S gas. It can be seen that the response value of this invention to 30 ppm H2S gas is approximately 10000. Figure 5 This is a response graph of the S / N-SnO2 semiconductor gas-sensitive material synthesized in Example 1 in detecting the H2S gas concentration gradient from 3 ppb to 50 ppm. It can be seen that the response of this invention to different hydrogen sulfide gases exhibits a certain regularity, providing strong support for the accurate detection of H2S concentration. Figure 6 This is a response diagram of the S / N-SnO2 semiconductor gas-sensitive material synthesized in Example 1 for detecting various gases. It can be seen that the present invention exhibits excellent selectivity for H2S gas, strong anti-interference ability, and can be well used as an H2S sensor.
[0058] S / N-SnO2 semiconductor gas-sensitive material exhibited excellent sensing performance in the detection of H2S gas. At 30℃, the S / N-SnO2 sensor had a response value of approximately 10,000 for detecting 30 ppm H2S gas, and showed different progressive response values for different concentrations of H2S gas; the detection limit reached the ppb level; it also exhibited excellent selectivity, being largely unaffected by interference from other gases in H2S detection.
[0059] Example 2:
[0060] Preparation of S / N-SnO2: 0.01 mol SnCl4·5H2O was dissolved in 80 mL of deionized water; hydrochloric acid (0.2 mol / L) was added to adjust the pH to 2, yielding tin source solution A. Thiourea (Sn:thiourea = 1:1), CTAB (5 g / L), and compound additives (EDTA + urea, added at 0.2 equivalents of Sn molar amounts) were added to tin source solution A, and the mixture was stirred for 30 min to obtain a precursor solution. The precursor solution was transferred to a reactor and hydrothermally reacted at 160℃ for 16 h to obtain a hydrothermal product. The hydrothermal product was washed, dried, and then impregnated twice with 0.08 mol / L thiourea solution for 10 min, filtered, and dried. It was calcined in Ar at 300℃ for 1 h, and then calcined in air at 500℃ for 3 h to obtain the S / N-SnO2 semiconductor gas-sensitive material.
[0061] H2S gas sensing performance test: The test procedure is the same as in Example 1. At 30°C, the response value of this S / N-SnO2 sensor is about 1047 when detecting 30ppm H2S gas, and the detection limit reaches the ppm level; the selectivity is slightly worse than that of the S / N-SnO2 semiconductor gas sensing material in Example 1.
[0062] Example 3:
[0063] Preparation of S / N-SnO2: 0.01 mol SnCl4·5H2O was dissolved in 80 mL of deionized water; hydrochloric acid (0.1 mol / L) was added to adjust the pH to 3, yielding tin source solution A. Thiourea (Sn:thiourea = 1:0.1), CTAB (8 g / L), and compound additives (citric acid + NaF, added in amounts equivalent to 0.1 molar amounts of Sn) were added to tin source solution A, and the mixture was stirred for 30 min to obtain a precursor solution. The precursor solution was transferred to a reactor and hydrothermally reacted at 150℃ for 20 h to obtain a hydrothermal product. The hydrothermal product was washed, dried, and then impregnated twice with 0.03 mol / L thiourea solution for 8 min, filtered, and dried. It was calcined in N2 at 250℃ for 1 h, and then calcined in air at 450℃ for 3 h to obtain the S / N-SnO2 semiconductor gas-sensitive material.
[0064] H2S gas sensing performance test: The test procedure is the same as in Example 1. At 30°C, the response value of this S / N-SnO2 sensor to detect 30ppm H2S gas is about 4837, and the detection limit reaches the ppm level; the selectivity is slightly worse than that of the S / N-SnO2 semiconductor gas sensing material in Example 1.
[0065] Example 4:
[0066] Preparation of S / N-SnO2: 0.01 mol SnCl4·5H2O was dissolved in 80 mL of deionized water; hydrochloric acid (0.1 mol / L) was added to adjust the pH to 2, yielding tin source solution A. Thiourea (Sn:thiourea = 1:0.8), CTAB (5 g / L), and additive NH4F (0.2 equivalent of the molar amount of Sn) were added to tin source solution A and stirred for 30 min to obtain a precursor solution. The precursor solution was transferred to a reactor and hydrothermally reacted at 180℃ for 12 h to obtain a hydrothermal product. The hydrothermal product was washed, dried, and then impregnated twice with 0.1 mol / L thiourea solution for 5 min, filtered, and dried. It was calcined in N2 at 350℃ for 0.5 h, and then calcined in air at 500℃ for 3 h to obtain the S / N-SnO2 semiconductor gas-sensitive material.
[0067] H2S gas sensing performance test: The test procedure is the same as in Example 1. At 30°C, the response value of this S / N-SnO2 sensor for detecting 30ppm H2S gas is about 6184, and the detection limit reaches the ppm level; the selectivity is slightly worse than that of the S / N-SnO2 semiconductor gas sensing material in Example 1.
[0068] Example 5:
[0069] Preparation of S / N-SnO2: 0.01 mol SnCl4·5H2O was dissolved in 80 mL of deionized water; hydrochloric acid (0.1 mol / L) was added to adjust the pH to 2, yielding tin source solution A. Thiourea (Sn:thiourea = 1:0.5), CTAB (5 g / L), and compound additives (EDTA + NH4F, added at 0.2 and 0.05 molar equivalents of Sn, respectively) were added to tin source solution A and stirred for 30 min to obtain a precursor solution. The precursor solution was transferred to a reactor and hydrothermally reacted at 180℃ for 12 h to obtain a hydrothermal product. The hydrothermal product was washed, dried, and then impregnated twice with 0.01 mol / L thiourea solution for 10 min, filtered, and dried. It was calcined in N2 at 300℃ for 1 h, and then calcined in air at 650℃ for 1 h to obtain the S / N-SnO2 semiconductor gas-sensitive material.
[0070] H2S gas sensing performance test: The test procedure is the same as in Example 1. At 30°C, the response value of this S / N-SnO2 sensor is about 2003 when detecting 30ppm H2S gas, and the detection limit reaches the ppm level; the selectivity is slightly worse than that of the S / N-SnO2 semiconductor gas sensing material in Example 1.
[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing an S, N co-doped SnO2 semiconductor gas-sensitive material, characterized in that, The method includes the following steps: Step S01: Dissolve SnCl4·5H2O in deionized water, add hydrochloric acid to adjust the pH of the solution, and obtain tin source solution A; Step S02: Add thiourea, CTAB and compound additives to tin source solution A, stir evenly to obtain precursor solution, transfer precursor solution to reaction vessel, react in hydrothermal at 120-200℃ for 6-20 h to obtain hydrothermal product; Step S03: After washing and drying the hydrothermal product, impregnate it a second time with thiourea solution, filter it out and dry it. The S / N-SnO2 semiconductor gas-sensitive material is obtained by two-stage calcination treatment.
2. The method for preparing the S, N co-doped SnO2 semiconductor gas-sensitive material according to claim 1, characterized in that, In step S01, the hydrochloric acid concentration is 0.05–0.5 mol / L, and the target pH is 1–3.
3. The method for preparing the S, N co-doped SnO2 semiconductor gas-sensitive material according to claim 1, characterized in that, In step S02, the molar ratio of SnCl4·5H2O to thiourea is 1:(0.1–10), and the amount of CTAB added is 0.1–10 g / L.
4. The method for preparing the S, N co-doped SnO2 semiconductor gas-sensitive material according to claim 1, characterized in that, In step S02, the compound additive consists of one or more of citric acid, NH4F, NaF, urea, and EDTA, and the amount added is 0.05–0.5 times the molar amount of Sn.
5. The method for preparing the S, N co-doped SnO2 semiconductor gas-sensitive material according to claim 1, characterized in that, In step S03, the concentration of the thiourea solution is 0.01–0.1 mol / L, and the immersion time is 1–15 min.
6. The method for preparing the S, N co-doped SnO2 semiconductor gas-sensitive material according to claim 1, characterized in that, In step S03, the two-stage calcination process involves two stages: the first stage is the inert stage, which is calcined at 250-350℃ for 0.5-2 h in an N2 or Ar atmosphere; the second stage is the re-oxidation stage, which is calcined at 400-650℃ for 1-4 h in an air atmosphere.
7. A semiconductor gas-sensitive material co-doped with S and N, SnO2, characterized in that, The semiconductor gas-sensitive material is prepared by the preparation method described in any one of claims 1-6. The semiconductor gas-sensitive material is an S / N-SnO2 semiconductor gas-sensitive material. The S / N-SnO2 semiconductor gas-sensitive material has SnO2 as the main crystal phase. S and N are introduced into the SnO2 lattice or near-surface defect sites to form an asymmetric structural unit of Sn–S–Sn–O–Sn–N.
8. The S, N co-doped SnO2 semiconductor gas-sensitive material according to claim 7, characterized in that, The Sn–S–Sn–O–Sn–N asymmetric structural unit provides both sulfur affinity anchor sites and polar / basic hydrogen accepting sites, which together constitute asymmetric sites.
9. An application of a semiconductor gas-sensitive material co-doped with S and N, SnO2, characterized in that, The semiconductor gas-sensitive material prepared by any one of the preparation methods in claims 1-6, or the semiconductor gas-sensitive material in any one of claims 7-8, is ground and then coated or deposited on a substrate with electrodes to form a resistive gas-sensitive element for selective detection of H2S.