Acetone sensor based on double perovskite sensitive electrodes as well as preparation method and application of acetone sensor

Abstract

The invention discloses an acetone sensor based on double perovskite sensitive electrodes as well as a preparation method and application of the acetone sensor. The acetone sensor comprises a supporting substrate with a platinum heating wire, a bonding layer, a solid electrolyte substrate and an electrode layer which are sequentially stacked, the electrode layer comprises a reference electrode and a sensitive electrode; the sensitive electrode material is LaBaCo (2-x) FexO (5 + delta), and x is greater than or equal to 0 and less than or equal to 0.5. The Fe element is introduced into the sensitive electrode material, the conductivity and catalytic activity of the sensitive electrode material are changed, and more active sites are provided for interaction of acetone gas and the sensitive electrode material, so that the response speed, the sensitivity and the lower detection limit of the acetone sensor are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to an acetone sensor based on a double perovskite sensitive electrode, and a preparation method and application thereof. Background Art

[0002] Acetone (molecular formula: CH₃COCH₃) is a typical volatile organic compound (VOC). It is colorless and transparent, with relatively active physical and chemical properties. It is flammable (flash point -20°C), volatile, and explosive. Studies have shown that exposure to excessive acetone concentrations poses a serious threat to human health. Low concentrations can irritate the skin and mucous membranes, causing respiratory and eye discomfort. Long-term exposure can suppress the central nervous system. Higher concentrations can cause headaches, vomiting, and even coma. In medical diagnostics, acetone can be used as a breath biomarker for diagnosing diabetes. Studies have shown that acetone levels in the breath of diabetic patients exceed 1.8 ppm, while healthy individuals have acetone levels ranging from 0.3 to 0.9 ppm. The former have significantly higher acetone levels, 2 to 6 times higher. Currently, diabetes diagnosis relies primarily on blood sampling and testing, which is invasive to the skin and blood vessels, time-consuming, and costly. It requires specialized training and cannot monitor blood sugar levels in real time. Therefore, designing an acetone gas sensor for breath analysis is of great significance for noninvasive and real-time monitoring of blood glucose levels in diabetic patients.

[0003] Currently, the main technologies for detecting acetone gas include gas chromatography, mass spectrometry, and cavity ring-down spectroscopy. Gas chromatography utilizes the differences in the distribution coefficients of different sample components between the stationary and mobile phases to separate acetone from other components by allowing them to pass through the chromatographic column at different speeds. The separated acetone molecules enter a hydrogen flame ionization detector (FID), where they combust in a hydrogen flame, generating ions and electrons. The resulting electrical signal intensity is proportional to the acetone concentration, allowing the acetone concentration to be determined. Mass spectrometry ionizes sample gas molecules into ions, which are then fed into a mass analyzer. The ions are separated and filtered based on their mass-to-charge ratios, and the characteristic ions of acetone are then fed into the detector. The generated electrical signal intensity is proportional to the number of ions, allowing the acetone concentration to be determined. Cavity ring-down spectroscopy is a method that has only recently been applied to acetone detection. Its operating principle is to utilize the exponential decay of light intensity in an optical resonant cavity to quantitatively analyze gas concentration information by measuring the decay time of the light intensity. The aforementioned methods for detecting acetone concentrations through spectroscopy and mass spectrometry offer high sensitivity and accuracy. However, the equipment used is expensive and requires high costs, requiring trained personnel for operation and maintenance. The testing process is lengthy and cannot achieve real-time acetone concentration detection. Furthermore, existing acetone detection technologies utilize large equipment that is difficult to integrate into mobile devices, hindering the development of lightweight, portable acetone detection instruments. Furthermore, considerations must be taken into account when determining the concentration of acetone in breath analysis for diabetes diagnosis. In actual medical breath analysis, multiple interfering gases are often present, requiring the sensor to exhibit excellent selectivity for acetone. Furthermore, human exhaled breath inevitably contains significant amounts of water vapor, requiring the sensor to exhibit good moisture resistance.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide an acetone sensor based on a double perovskite sensitive electrode, as well as its preparation method and application. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] In the first aspect, the present invention provides an acetone sensor based on a double perovskite sensitive electrode, comprising a supporting substrate with a platinum heating wire, an adhesive layer, a solid electrolyte substrate and an electrode layer stacked in sequence; the electrode layer comprises a reference electrode and a sensitive electrode; the sensitive electrode material is LaBaCo 2-x Fe x O 5+δ , where 0≤x≤0.5.

[0007] In one embodiment of the present invention, the sensitive electrode material is LaBaCo 2-x Fe x O 5+δ , where 0.15<x<0.25.

[0008] In one embodiment of the present invention, the material of the support substrate is aluminum oxide;

[0009] The material of the solid electrolyte substrate is any one of yttria-stabilized zirconia, cerium-based oxide, lithium ion conductor, and proton conductor.

[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned acetone sensor based on the double perovskite sensitive electrode, comprising the following steps:

[0011] S1. Obtain a solid electrolyte substrate; and form a reference electrode in a first electrode region on a first surface of the solid electrolyte substrate.

[0012] S2. Preparing a sensitive electrode material, wherein the preparing the sensitive electrode material comprises:

[0013] S211, mixing lanthanum nitrate hexahydrate, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, and barium chloride dihydrate in a molar ratio of 1:(2-x):x:1 to obtain a mixture, wherein 0≤x≤0.5; adding a mixed polar solvent to the mixture, and stirring in a water bath to obtain a mixed solution;

[0014] S212, adding citric acid to the mixed solution, and stirring for 60 to 90 minutes to obtain a sol;

[0015] The molar number of the citric acid is n1, the sum of the molar numbers of lanthanum ions, cobalt ions, iron ions and barium ions in the mixed solution is n2, and n1=(1-2)*n2;

[0016] S213, drying the sol at room temperature for 20-28 hours, and then air-drying at 50-70° C. for 20-28 hours to obtain a gel;

[0017] S214, sintering the gel, wherein the sintering process is: heating to 850-1200°C at a heating rate of 2-4°C / min and sintering for 2.5-3.5h to obtain the sensitive electrode material LaBaCo 2-x Fe x O 5+δ .

[0018] S3, LaBaCo prepared in step S2 2-x Fe x O 5+δ, forming a sensitive electrode in the second electrode region on the first surface of the solid electrolyte substrate; the first electrode region and the second electrode region are spaced apart on the first surface of the solid electrolyte substrate;

[0019] S4. Bonding the second surface of the solid electrolyte substrate obtained in step S3 to a supporting substrate having a platinum heating wire through an inorganic adhesive, with the first surface and the second surface arranged opposite to each other, to obtain an acetone sensor based on a double perovskite sensitive electrode.

[0020] In one embodiment of the present invention, in step S1, forming the reference electrode on the first electrode region on the first surface of the solid electrolyte substrate comprises: ultrasonically cleaning the surface of the solid electrolyte substrate and then uniformly coating the first electrode region on the first surface of the solid electrolyte substrate with platinum slurry;

[0021] Obtain a first platinum wire, fold the first platinum wire from the middle into a V-shaped structure, and fix the vertex of the first platinum wire of the V-shaped structure to the reference electrode as an electrode connection lead. Sinter the wire at 850-1000°C in a muffle furnace for 30-50 minutes to form a platinum reference electrode with a thickness of 15-30 μm.

[0022] In one embodiment of the present invention, the method of uniformly coating the platinum slurry on the first electrode region of the first surface of the solid electrolyte substrate is any one of brush coating, screen printing, spraying, dipping, spin coating or chemical vapor deposition.

[0023] In one embodiment of the present invention, in step S3, forming the sensitive electrode includes:

[0024] S311, forming a platinum point at the center of the second electrode region on the first surface of the solid electrolyte substrate; obtaining a second platinum wire, folding the second platinum wire from the middle into a V-shaped structure, fixing the vertex of the second platinum wire in the V-shaped structure to the platinum point, and sintering in a muffle furnace at a temperature of 850-1000° C. for 30-50 minutes;

[0025] S312, the LaBaCo obtained in step S214 2-x Fe x O 5+δ Dissolved in deionized water to obtain LaBaCo 2-x Fe x O 5+δ slurry; LaBaCo 2-x Fe x O 5+δ The slurry is coated on the second electrode area and completely covers the platinum point, and is sintered in a muffle furnace with a sintering heating rate of 3 to 8°C / min and sintered at 850 to 1000°C for 1.5 to 2.5 hours to form a sensitive electrode on the first surface of the solid electrolyte substrate.

[0026] In one embodiment of the present invention, in step S4, the inorganic binder comprises sodium silicate and aluminum oxide, and the volume ratio of the sodium silicate to aluminum oxide is (2.5-4):1.

[0027] In one embodiment of the present invention, in step S211, the mixed polar solvent is ultrapure water and ethanol in a volume ratio of 1:1; and the water bath stirring is stirring at 30-50° C. for 2-3 hours.

[0028] In a second aspect, the present invention provides an application of the above-mentioned acetone sensor based on the double perovskite sensitive electrode in the preparation of an acetone detection device.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. In the acetone sensor provided by the present invention, the sensitive electrode material is a double perovskite structure, and the sensing performance of the acetone sensor to acetone gas is improved by adjusting the ratio of cobalt ions and iron ions in the B-site metal cations. 2-x Fe x O 5+δ Introducing Fe into the sensitive material can modulate the band structure of the sensitive electrode material, changing its conductivity and catalytic activity, thereby improving the response speed and sensitivity of the acetone sensor. Furthermore, the introduction of Fe can increase the concentration of oxygen vacancies in the sensitive electrode material, providing more active sites and thus enhancing the interaction between acetone gas molecules and the surface of the sensitive electrode material. The increase in oxygen vacancies not only helps to improve the catalytic activity of the sensitive electrode material, but also enhances its ability to detect low-concentration acetone. Testing has shown that the detection limit of the acetone sensor provided by the present invention is as low as 0.2 ppm, which can meet the needs of detecting acetone content in the environment or in the breath of the test subject.

[0031] 2. The preparation method of the acetone sensor provided by the present invention is simple and easy to operate, has low preparation cost, and is easy to implement industrial production; the prepared acetone sensor is small in size, providing a feasible solution for the realization of a small, portable, handheld acetone detection device.

[0032] 3. The acetone sensor provided by the present invention has the advantages of fast response, short detection time, and high sensitivity when used to detect acetone content. In particular, it is non-invasive, has high detection specificity, high moisture resistance, and short detection time for pre-diagnosis of diabetic patients, thereby improving the compliance of diabetic patients in diagnosis and treatment.

[0033] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the description, serve to explain the principles of the invention. Obviously, the drawings described below are only some embodiments of the present invention, and it is clear that those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0035] Figure 1 This is a schematic cross-sectional view of an acetone sensor based on a double perovskite sensitive electrode in one embodiment of the present invention;

[0036] Figure 2 Schematic diagram of a flow chart of a method for preparing an acetone sensor based on a double perovskite sensitive electrode in one embodiment of the present invention;

[0037] Figure 3 This is a schematic flow chart of a method for preparing a sensitive electrode material for an acetone sensor in one embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the three-dimensional structure of an acetone sensor based on a double perovskite sensitive electrode in one embodiment of the present invention;

[0039] Figure 5 This is an X-ray diffraction characterization diagram of the sensitive electrode material of the acetone sensor in some embodiments of the present invention;

[0040] Figure 6 This is a scanning electron microscope characterization image of the sensitive electrode material of the acetone sensor in some embodiments of the present invention;

[0041] Figure 7 Graph showing the sensitivity relationship between the response value of an acetone sensor and the logarithm of acetone concentration in some embodiments of the present invention;

[0042] Figure 8 This is a graph showing the response recovery curve of the acetone sensor device to acetone gas of different concentrations at a working temperature of 535°C in one embodiment of the present invention;

[0043] Figure 9 This is a schematic diagram of the detection sensitivity of an acetone sensor device to acetone gas of different concentrations at an operating temperature of 535°C in one embodiment of the present invention;

[0044] Figure 10 This is a schematic diagram of the repeatability test results of an acetone sensor device in one embodiment of the present invention;

[0045] Figure 11 This is a schematic diagram of the specific detection results of the acetone sensor device in one embodiment of the present invention;

[0046] Figure 12 This is a schematic diagram of the detection results of the acetone response value of the acetone sensor device under different humidity environments in one embodiment of the present invention;

[0047] Figure 13 This is a schematic diagram of detection results of acetone response value drift of an acetone sensor device under different humidity environments in one embodiment of the present invention;

[0048] Figure 14 This is a schematic diagram of the response time and recovery time detection results of an acetone sensor device to 5 ppm acetone gas in one embodiment of the present invention.

[0049] The reference numerals are as follows:

[0050] 1-sensitive electrode, 2-reference electrode, 3-solid electrolyte substrate, 4-adhesive layer, 5-platinum heating wire, 6-support substrate, 7-platinum wire lead, 8-hexagonal tube socket. DETAILED DESCRIPTION

[0051] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent identical or similar structures, and thus their detailed description will be omitted. Furthermore, the figures are merely schematic illustrations of the present invention and are not necessarily drawn to scale.

[0052] Although relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used herein for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It will be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via the other structure.

[0053] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0054] The embodiment of the present invention provides an acetone sensor based on a double perovskite sensitive electrode, such as Figure 1 As shown, it includes a support substrate 6 with a platinum heating wire, an adhesive layer 4, a solid electrolyte substrate 3 and an electrode layer stacked in sequence; the electrode layer includes a reference electrode 2 and a sensitive electrode 1; the material of the sensitive electrode is LaBaCo 2-x Fe x O 5+δ , wherein 0≤x≤0.5. In the acetone sensor provided in the embodiment of the present invention, the sensitive electrode material is a double perovskite structure, and the sensing performance of the acetone sensor to acetone gas is improved by adjusting the ratio of cobalt ions and iron ions at the B site. On the one hand, in LaBaCo 2-x Fe x O 5+δ The introduction of Fe into the structure modulates the energy band structure of the sensitive electrode material, altering its conductivity and catalytic activity, thereby improving the response speed and sensitivity of the acetone sensor. Furthermore, the introduction of Fe increases the concentration of oxygen vacancies in the sensitive electrode material, providing more active sites and enhancing the interaction between acetone gas molecules and the surface of the sensitive electrode material. The increase in oxygen vacancies not only helps enhance the catalytic activity of the sensitive electrode material but also improves its ability to detect low-concentration acetone. Furthermore, the proportion of iron ions should not be too high. Excessive Fe ions may inhibit catalytic performance and weaken the conductivity of the sensitive electrode material, which in turn weakens the response of the acetone sensor.

[0055] In one embodiment of the present invention, the sensitive electrode material is LaBaCo 2-x Fe x O 5+δ , wherein 0.15<x<0.25. When the Fe ions in the sensitive electrode material are within the range provided in this embodiment, the prepared acetone sensor has a higher response sensitivity.

[0056] In one embodiment of the present invention, the sensitive electrode material is LaBaCo 2-x Fe x O 5+δ , where x = 0.2.

[0057] In one embodiment of the present invention, the support substrate 6 is made of aluminum oxide, and the solid electrolyte substrate 3 is made of any one of yttria-stabilized zirconia, cerium-based oxides, lithium ion conductors, and proton conductors. For example, cerium-based oxides (GDC), lithium ion conductors (LLZO), and proton conductors (BCZY) can all be used as the solid electrolyte layer.

[0058] The embodiment of the present invention also provides a method for preparing the above-mentioned acetone sensor based on the double perovskite sensitive electrode, such as Figure 2 As shown, the following steps are included:

[0059] S1 . Obtain a solid electrolyte substrate 3 ; and form a reference electrode 2 in a first electrode region on a first surface of the solid electrolyte substrate 3 .

[0060] In one example, forming the reference electrode 2 includes: ultrasonically cleaning the surface of the solid electrolyte substrate 3 , and then uniformly coating the platinum slurry on the first electrode region of the first surface of the solid electrolyte substrate 3 .

[0061] Obtain a first platinum wire, fold the first platinum wire from the middle into a V-shaped structure, and fix the vertex of the first platinum wire of the V-shaped structure to the center position of the reference electrode 2 as an electrode connection lead. Sinter it in a muffle furnace at 850-1000°C for 30-50 minutes to form a platinum reference electrode 2 with a thickness of 15-30 μm.

[0062] For example, the platinum slurry may be uniformly coated on the first electrode region of the first surface of the solid electrolyte substrate 3 by any one of brush coating, screen printing, spraying, dipping, spin coating or chemical vapor deposition.

[0063] S2. Preparation of sensitive electrode materials, such as Figure 3 As shown, the preparation of the sensitive electrode material includes:

[0064] S211. Mix lanthanum nitrate hexahydrate, cobalt nitrate hexahydrate, ferric nitrate nonahydrate and barium chloride dihydrate in a molar ratio of 1:(2-x):x:1 to obtain a mixture, wherein 0≤x≤0.5; add a mixed polar solvent to the mixture and stir in a water bath to obtain a mixed solution.

[0065] For example, the mixed polar solvent is ultrapure water and ethanol in a volume ratio of 1:1. Using a mixed polar solvent can reduce the hydrolysis rate and improve the stability of the sol in subsequent steps.

[0066] Exemplarily, the stirring in a water bath is stirring at 30-50° C. for 120-180 min.

[0067] Furthermore, the stirring in the water bath was carried out at 35° C. for 150 min. The stirring at a lower temperature was to avoid the ethanol from volatilizing too quickly, which would lead to the instability of the sol in the subsequent steps.

[0068] S212, adding citric acid to the mixed solution, stirring for 60 to 90 minutes to obtain a sol, and extending the stirring time to ensure that the hydrolysis and polycondensation reactions proceed fully.

[0069] The molar number of the citric acid is n1, the sum of the molar numbers of lanthanum ions, cobalt ions, iron ions and barium ions in the mixed solution is n2, and n1=(1-2)*n2 is satisfied.

[0070] Preferably, the molar number n1 of citric acid and the sum of the molar numbers n2 of the metal ions satisfy n1=n2.

[0071] S213. Dry the sol at room temperature for 20-28 hours, and then vacuum dry it at 50-70°C for 20-28 hours to obtain a gel.

[0072] For example, gradient drying is used, and the sol is evaporated and dried at room temperature for 24 hours, and then transferred to an oven and dried under forced air at 60° C. for 24 hours to form a gel.

[0073] S214, sintering the gel, wherein the sintering process is: heating to 850-1200°C at a heating rate of 2-4°C / min and sintering for 2.5-3.5h to obtain the sensitive electrode material LaBaCo 2-x Fe x O 5+δ .

[0074] For example, the sintering process is to increase the temperature to 1000°C at a heating rate of 3°C / min and sinter for 3 hours. In this way, the temperature is slowly increased to the sintering temperature and maintained at the temperature for a long time to avoid the formation of large amounts of carbon deposits during the sintering process.

[0075] S3, LaBaCo prepared in step S2 2-x Fe x O 5+δ , a sensitive electrode 1 is formed in the second electrode region on the first surface of the solid electrolyte substrate 3 ; the first electrode region and the second electrode region are spaced apart on the first surface of the solid electrolyte substrate 3 .

[0076] In one example, in step S3, the forming of the sensitive electrode 1 includes: S311, forming a platinum point at the center position of the second electrode area on the first surface of the solid electrolyte substrate 3; obtaining a second platinum wire, folding the second platinum wire from the middle into a V-shaped structure, and fixing the vertex of the second platinum wire of the V-shaped structure at the platinum point, and sintering at a temperature of 850 to 1000° C. in a muffle furnace for 30 to 50 minutes.

[0077] S312, the LaBaCo obtained in step S214 2-x Fe x O 5+δ Dissolved in deionized water to obtain LaBaCo 2-x Fe x O 5+δ slurry; LaBaCo 2-x Fe x O 5+δThe slurry is coated on the second electrode area and completely covers the platinum point, and is sintered in a muffle furnace with a sintering heating rate of 2-4°C / min and sintered at 850-1000°C for 1.5-2.5 to form a sensitive electrode 1 on the first surface of the solid electrolyte substrate 3.

[0078] S4. Bonding the second surface of the solid electrolyte substrate 3 obtained in step S3 to a supporting substrate having a platinum heating wire through an inorganic adhesive, with the first surface and the second surface arranged opposite to each other, to obtain an acetone sensor based on a double perovskite sensitive electrode.

[0079] In one example, the inorganic binder includes sodium silicate and aluminum oxide, and the volume ratio of the sodium silicate to aluminum oxide is (2.5-4): 1. For example, the volume ratio of the sodium silicate to aluminum oxide can be 2.5:1, 3:1, 3.5:1, or 4:1.

[0080] Preferably, the volume ratio of sodium silicate to aluminum oxide is 3:1.

[0081] The present invention also provides a use of the aforementioned double perovskite-based acetone sensor in the preparation of an acetone detection device. The acetone sensor provided in the aforementioned embodiment has a flat-plate structure and can be integrated onto a printed circuit board (PCB) to form an acetone detection device for detecting acetone levels in an environment or in a subject's exhaled breath.

[0082] In one example, a simple acetone sensing device can be built using an STM32F103R8T6 main control module, an ADS1115 analog-to-digital converter module, and a stable acetone sensor. This compact acetone sensing device offers a feasible solution for implementing a small, portable, and handheld acetone detection device.

[0083] For example, an acetone sensor can be used to measure the acetone content in a subject's exhaled breath to assist in determining diabetes risk. The acetone sensor's different colored LED lights and screen can indicate the acetone content in a person's exhaled breath, reflecting their blood sugar level. When the acetone content in the exhaled breath is within the range of 0.3-0.9ppm, the sensor's green light stays on, indicating that the individual's blood sugar is normal. When the acetone concentration in the exhaled breath is within the range of 0.9-1.8ppm, the sensor's yellow light turns on, indicating that the individual's blood sugar is elevated. When the acetone concentration in the exhaled breath reaches or exceeds 1.8ppm, the acetone sensor's red light turns on and a long buzzer sounds, indicating that the individual's blood sugar is too high and may be diabetic. This device provides a non-invasive testing method for the subject, facilitating early detection and treatment of diabetes.

[0084] The acetone sensor based on the double perovskite sensitive electrode and the preparation method thereof provided by the present invention are further described below in conjunction with specific embodiments.

[0085] Example 1

[0086] The acetone sensor based on the double perovskite sensitive electrode prepared by the present invention is a planar structure constructed using an 8% Y2O3 doped YSZ (yttrium stabilized zirconia) substrate (the YSZ substrate is 2 mm × 2 mm square and 0.3 mm thick). Figure 4 The steps to make an acetone sensor include:

[0087] Step S1: Fabricate the platinum reference electrode 2, sensitive electrode 1, and platinum heating wire leads: After ultrasonically cleaning the surface of a YSZ (yttrium-stabilized zirconia) substrate, a platinum slurry (Guiyan Platinum Co., Ltd., batch number 2021060701, model PE-Pt-7840) was evenly applied to the first electrode area on the first surface of the substrate using a coating brush, forming a reference electrode 2 with a width of 0.6 mm and a thickness of 20 μm. A first platinum wire with a diameter of 0.05 mm and a length of 1 cm was folded from the middle into a V-shaped structure, and its vertex was fixed to the center of the reference electrode 2 to serve as the reference electrode 2 connection lead. A first platinum point was formed in the second electrode area on the first surface of the YSZ (yttrium-stabilized zirconia) substrate. A second platinum wire of the same length was folded and bonded to the first platinum point. A second platinum point was formed at each end of the "J"-shaped platinum heating wire 5 supporting the substrate. Two third platinum wires, each 1 cm long, were bonded to the second platinum points to serve as the heating plate leads. Then, the YSZ (yttrium-stabilized zirconia) substrate with the first and second platinum wire leads and the support substrate with the platinum heating wire were placed in a muffle furnace and sintered at 950° C. for 30 minutes to remove impurities such as terpineol in the platinum slurry.

[0088] Step S2: Making the sensitive electrode material LaBaCo 2-x Fe x O 5+δ (x=0.2).

[0089] First synthesize LaBaCo 2-x Fe x O 5+δ (x=0.2) material, including the following process:

[0090] Step S211, weighing lanthanum nitrate hexahydrate La(NO3)3·6H2O, cobalt nitrate hexahydrate Co(NO3)2·6H2O, iron nitrate nonahydrate Fe(NO3)3·9H2O, and barium chloride dihydrate BaCl2·2H2O in a molar ratio of 1:1.8:0.2:1, adding 40 mL of a mixed solution of ultrapure water and ethanol in a volume ratio of 1:1 as a solvent, placing in a 35°C water bath and stirring for 150 minutes to ensure sufficient dissolution and mixing to obtain a mixed solution;

[0091] Step S212: adding citric acid (C6H8O7) to the mixed solution in a molar ratio of citric acid (C6H8O7) to total metal ions of 1:1, and then continuing to stir for 60 minutes to form a sol;

[0092] Step S213: using gradient drying to volatilize the sol at room temperature for 24 hours, then transferring it to an oven and drying it with forced air at 60° C. for 24 hours to form a gel;

[0093] Step S214: Place the gel in a muffle furnace and sinter at 1000°C for 3 hours at a heating rate of 3°C / min to obtain the desired sensitive electrode material LaBaCo 2-x Fe x O 5+δ (x=0.2).

[0094] Step S3: Using sensitive electrode material LaBaCo 2-x Fe x O 5+δ (x=0.2) to form a sensitive electrode, including the following operations:

[0095] S311, LaBaCo 2-x Fe x O 5+δ (x = 0.2) was dissolved in ultrapure water and fully ground to obtain LaBaCo 2-x Fe x O 5+δ (x=0.2) slurry; use a fine brush to mix LaBaCo 2-x Fe x O 5+δ (x=0.2) The slurry is applied to the second electrode area and completely covers the first platinum point;

[0096] S312. Place the YSZ substrate in a muffle furnace for sintering at a sintering heating rate of 3°C / min and sinter at 800°C for 2 hours to ensure that the sensitive electrode material is firmly attached to the YSZ (yttrium stabilized zirconia) substrate. After cooling to room temperature, take it out and form a sensitive electrode on the first surface of the YSZ substrate.

[0097] Step S4, preparing an inorganic adhesive: adding 3.0 g of Al2O3 powder to 6 ml of sodium silicate (Na2SiO3·9H2O), mixing and stirring uniformly to prepare an inorganic adhesive.

[0098] An inorganic adhesive was applied to an aluminum oxide substrate with a platinum heating filament. The second surface of a YSZ (yttrium-stabilized zirconia) substrate was then placed over the aluminum oxide substrate with the platinum heating filament, bonding the two together. The bonded device was then baked under an infrared lamp for 30 minutes to firmly bond the YSZ (yttrium-stabilized zirconia) substrate and the aluminum oxide substrate with the platinum heating filament, forming acetone sensor 1.

[0099] The six platinum wire leads 7 of the prepared acetone sensor 1 are respectively welded to the six terminals of the hexagonal tube socket 8 and encapsulated using a mesh cap of appropriate size. The platinum heating wire is then heated with an appropriate current by a current source. The acetone sensor 1 is aged at 500° C. The acetone gas of the same concentration is tested using the acetone sensor 1 every day until the sensitivity characteristics of the acetone sensor 1 reach a stable state, thereby obtaining a stable acetone sensor 1.

[0100] Example 2

[0101] The difference between Example 2 and Example 1 is that the sensitive electrode material prepared and used is LaBaCo 2-x Fe x O 5+δ (x=0.05), and the acetone sensor 2 was prepared.

[0102] The six leads of the acetone sensor 2 prepared in Example 2 were respectively welded to the six terminals of the hexagonal tube socket and encapsulated with a mesh cap of appropriate size; the platinum heating wire was then heated with an appropriate current through a current source, and the acetone sensor 2 was aged at 500°C. The acetone gas of the same concentration was detected using the acetone sensor 2 every day until the sensitivity of the acetone sensor 2 reached a stable state, thereby obtaining a stable acetone sensor 2.

[0103] Example 3

[0104] The difference between Example 3 and Example 1 is that the sensitive electrode material prepared and used is LaBaCo 2-x Fe x O 5+δ (x=0), and the acetone sensor 3 was prepared.

[0105] The six leads of the acetone sensor 3 prepared in Example 3 were welded to the six terminals of the hexagonal tube socket and encapsulated with a mesh cap of appropriate size. The platinum heating wire was then heated with an appropriate current by a current source. The acetone sensor 3 was aged at 500°C and the acetone gas of the same concentration was tested using the acetone sensor 3 every day until the sensitivity of the acetone sensor 3 reached a stable state. Thus, a stable acetone sensor 3 was obtained.

[0106] The performance of the sensitive electrode materials and the stable acetone sensors in Examples 1 to 3 was tested:

[0107] 1. The sensitive electrode material LaBaCo prepared in Examples 1 to 3 2-x Fe x O 5+δ (x=0.2、0.05、0) were irradiated with X-ray to obtain X-ray diffraction characterization patterns. Figure 5 As shown, with LaBaCo 2-x Fe x O 5+δ (x=0) comparison, LaBaCo 2-x Fe x O 5+δ (x=0.05) and LaBaCo 2-x Fe x O 5+δ (x=0.2) has characteristic peaks at 2θ=31.4° and 41.1°, indicating that Fe element is doped into the sensitive electrode material. Due to the different ratios of Fe element introduction, LaBaCo 2-x Fe x O 5+δ The characteristic peak intensity of (x=0.2) at 2θ=31.4°, 41.1° is greater than that of LaBaCo 2-x Fe x O 5+δ The characteristic peak intensities at 2θ=31.4° and 41.1° (x=0.05) are shown in Figure 2. The diffraction peaks on the JCPDS no. 32-0480 standard card appear in all three series of materials, and each diffraction peak is very clear, indicating that the synthesized sensitive materials have a good crystal structure.

[0108] 2. The sensitive electrode material LaBaCo prepared in Examples 1 to 3 2-x Fe x O 5+δ (x=0.2、0.05、0) were scanned by electron microscope, and the results were as follows Figure 6 Wherein, (a) and (b) are LaBaCo in Example 3 2-x Fe x O5+δ (x=0) The scanning electron microscope characterization images of the material at different magnifications show that the obtained sensitive electrode material has certain small pores, which exposes some active sites. (c) and (d) are LaBaCo 2-x Fe x O 5+δ (x = 0.05) Scanning electron microscope characterization images of the material at different magnifications. It can be seen from the figure that the obtained sensitive electrode material has increased pores, which exposes more active sites. (e) and (f) are LaBaCo in Example 1 2-x Fe x O 5+δ (x=0.2) Scanning electron microscope characterization images of the material at different magnifications. It can be seen from the figure that the obtained sensitive electrode material has smaller and more uniform particle size and larger pore size. This morphological feature is conducive to the diffusion of acetone gas molecules, allowing more gas molecules to quickly reach the TPB (three-phase interface), promoting the electrochemical reaction at the TPB (three-phase interface), and further improving the sensitivity of the acetone sensor to acetone detection.

[0109] 3. See Figure 7 , respectively, using the stable state acetone sensors in Example 1, Example 2 and Example 3 to detect acetone of different concentrations, and plotting the relationship curves between the response values of the three acetone sensors and the logarithm of the acetone concentration. Figure 7 As shown in the figure, the horizontal axis is the concentration of acetone, and the vertical axis is the response voltage value (mV) of the acetone sensor. The response values of the acetone sensors in the three stable states are linearly related to the logarithm of the acetone concentration, which is consistent with the mixed potential theory. Figure 7 It can be seen that with the increase of LaBaCo2O 5+δ The increase of the Fe doping ratio in LaBaCo 2-x Fe x O 5+δ The sensitivity of the gas sensor constructed by the sensitive electrode materials (x=0, 0.05, 0.2) gradually increases. When the ratio of Fe element doping is 0.2, the sensitivity of the gas sensor based on LaBaCo 1.8 Fe 0.2 O 5+δ The sensitivity of the sensor made of sensitive electrode material to acetone in the concentration range of 0.2-5ppm reaches -11.38mV / decade.

[0110] Example 4

[0111] Construction of an acetone sensor device: Combining the STM32F103R8T6 main control module and the ADS1115 analog-to-digital converter module, a simple circuit is designed to build an acetone sensor device with the help of a stable acetone sensor 1.

[0112] The performance of the acetone sensor device prepared in Example 4 was tested:

[0113] 1. See Figure 8 and Figure 9 , using the acetone detection device in Example 4, different concentrations of acetone were measured at an operating temperature of 535°C. Figure 8 It shows that as the acetone concentration increases, the response value gradually increases; Figure 9 It can be seen that there is a good piecewise linear relationship between the sensor response value and the logarithm of the acetone concentration. The sensitivity of the sensor to 0.2-5 ppm acetone (curve slope k = -11.38 mV / decace) is lower than the sensitivity to 5-210 ppm acetone (curve slope k = -32.12 mV / decace).

[0114] 2. See Figure 10 , using the acetone detection device in Example 4, 5ppm and 100ppm acetone were measured six times in a row at an operating temperature of 535°C to verify the repeatability of the acetone detection device provided by the embodiment of the present invention. Figure 10 The results shown in FIG5 show that the response value of the acetone detection device for continuous detection at two acetone concentrations remains basically stable and has good repeatability.

[0115] 3. See Figure 11 The acetone detection device in Example 4 was used to detect various detection gases (ethanol C2H6O, propanol C3H8O, benzene C6H6, trichloroethylene C2H3Cl3, toluene C7H8, xylene C8H 10 , formaldehyde CH2O, nitrogen dioxide NO2, ammonia NH3, hydrogen H2, acetone C3H6O) response results. Figure 11 As shown, the acetone detection device has high selectivity for acetone and low response to other detection gases. This shows that the acetone detection device provided by the present invention has strong anti-interference performance when detecting acetone, has good selectivity for acetone gas, and has high detection accuracy.

[0116] 4. See Figure 12 and Figure 13 The acetone detection device in Example 4 was used to test the performance at a working temperature of 535°C and different relative humidity (RH) environments. Figure 12 and Figure 13The following are the response-recovery and response drift curves for the sensor detecting 5 ppm acetone at 20% RH, 40% RH, 60% RH, 80% RH, and 100% RH, respectively. As can be seen from the figure, the sensor's response drift gradually increases as the relative humidity increases from 20% to 100%, reaching a maximum drift of 17%. Specifically, the response value fluctuates slightly from 20% to 40% relative humidity, but from 40% to 100% humidity has little effect on the response value of the acetone detection device, demonstrating its high stability even in high humidity conditions.

[0117] 5. See Figure 14 , using the acetone detection device in Example 4, the response time and recovery time of the sensor to 5ppm acetone gas were detected. Figure 14 As shown, when the acetone detection device detects 5ppm acetone gas, the response time is 6 seconds and the recovery time is 9 seconds, indicating that the acetone detection device provided by the present invention has a faster response speed and can significantly shorten the detection time.

[0118] Other embodiments of the present invention will readily occur to those skilled in the art after considering the specification and practicing the invention as disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art.

Claims

1. An acetone sensor based on a double perovskite sensitive electrode, characterized in that: It includes a supporting substrate with a platinum heating wire, an adhesive layer, a solid electrolyte substrate and an electrode layer which are stacked in sequence; The electrode layer includes a reference electrode and a sensitive electrode; the sensitive electrode material used in the sensitive electrode is LaBaCo 2- x Fe x O 5+δ , where 0≤x≤0.

5.

2. The acetone sensor based on double perovskite sensitive electrode according to claim 1, characterized in that: The sensitive electrode material is LaBaCo 2-x Fe x O 5+δ , where 0.15<x<0.

25.

3. The acetone sensor based on double perovskite sensitive electrode according to claim 1 or 2, characterized in that: The material of the supporting substrate is aluminum oxide; The material of the solid electrolyte substrate is any one of yttria-stabilized zirconia, cerium-based oxide, lithium ion conductor, and proton conductor.

4. A method for preparing an acetone sensor based on a double perovskite sensitive electrode according to claim 1, characterized in that: The following steps are involved: S1. Obtain a solid electrolyte substrate; forming a reference electrode in a first electrode region on a first surface of the solid electrolyte substrate; S2. Preparing a sensitive electrode material, wherein the preparing the sensitive electrode material comprises: S211, mixing lanthanum nitrate hexahydrate, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, and barium chloride dihydrate in a molar ratio of 1:(2-x):x:1 to obtain a mixture, wherein 0≤x≤0.5; adding a mixed polar solvent to the mixture, and stirring in a water bath to obtain a mixed solution; S212, adding citric acid to the mixed solution, and stirring for 60 to 90 minutes to obtain a sol; The molar number of the citric acid is n1, the sum of the molar numbers of lanthanum ions, cobalt ions, iron ions and barium ions in the mixed solution is n2, and n1=(1-2)*n2; S213, drying the sol at room temperature for 20-28 hours, and then air-drying at 50-70° C. for 20-28 hours to obtain a gel; S214, sintering the gel, wherein the sintering process is: heating to 850-1200°C at a heating rate of 2-4°C / min and sintering for 2.5-3.5h to obtain the sensitive electrode material LaBaCo 2-x Fe x O 5+δ ; S3, LaBaCo prepared in step S2 2-x Fe x O 5+δ , forming a sensitive electrode in the second electrode region on the first surface of the solid electrolyte substrate; the first electrode region and the second electrode region are spaced apart on the first surface of the solid electrolyte substrate; S4. Bonding the second surface of the solid electrolyte substrate obtained in step S3 to a supporting substrate having a platinum heating wire through an inorganic adhesive, with the first surface and the second surface arranged opposite to each other, to obtain an acetone sensor based on a double perovskite sensitive electrode.

5. The method for preparing an acetone sensor based on a double perovskite sensitive electrode according to claim 4, wherein: In step S1, forming a reference electrode in the first electrode region on the first surface of the solid electrolyte substrate includes: ultrasonically cleaning the surface of the solid electrolyte substrate and then uniformly coating the first electrode region on the first surface of the solid electrolyte substrate with platinum slurry; Obtain a first platinum wire, fold the first platinum wire from the middle into a V-shaped structure, and fix the vertex of the first platinum wire of the V-shaped structure to the reference electrode as an electrode connection lead. Sinter the wire at 850-1000°C in a muffle furnace for 30-50 minutes to form a platinum reference electrode with a thickness of 15-30 μm.

6. The method for preparing an acetone sensor based on a double perovskite sensitive electrode according to claim 5, characterized in that: The method of uniformly coating the platinum slurry on the first electrode area of the first surface of the solid electrolyte substrate is any one of brush coating, screen printing, spraying, dipping, spin coating or chemical vapor deposition.

7. The method for preparing an acetone sensor based on a double perovskite sensitive electrode according to claim 4, wherein: In step S3, forming the sensitive electrode includes: S311, forming a platinum point at the center of the second electrode region on the first surface of the solid electrolyte substrate; obtaining a second platinum wire, folding the second platinum wire from the middle into a V-shaped structure, fixing the vertex of the second platinum wire in the V-shaped structure to the platinum point, and sintering in a muffle furnace at a temperature of 850-1000° C. for 30-50 minutes; S312, the LaBaCo obtained in step S214 2-x Fe x O 5+δ Dissolved in deionized water to obtain LaBaCo 2-x Fe x O 5+δ slurry; LaBaCo 2-x Fe x O 5+δ The slurry is coated on the second electrode area and completely covers the platinum point; the solid electrolyte substrate is then placed in a muffle furnace for sintering at a sintering heating rate of 2 to 4°C / min and sintered at 850 to 1000°C for 1.5 to 2.5 hours to form a sensitive electrode on the first surface of the solid electrolyte substrate.

8. The method for preparing an acetone sensor based on a double perovskite sensitive electrode according to claim 4, wherein: In step S4, the inorganic binder includes sodium silicate and aluminum oxide, and the volume ratio of the sodium silicate to aluminum oxide is (2.5-4):

1.

9. The method for preparing an acetone sensor based on a double perovskite sensitive electrode according to claim 4, wherein: In step S211, the mixed polar solvent is ultrapure water and ethanol in a volume ratio of 1:1; The water bath stirring is carried out at 30-50° C. for 2-3 hours.

10. Use of the acetone sensor based on the double perovskite sensitive electrode according to any one of claims 1 to 3 in preparing an acetone detection device.

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