An acetone sensor based on a gd2zr2o7 solid electrolyte and a preparation method thereof
Patent Information
- Application Number
- CN202311587735.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-27
- Publication Date
- 2026-09-22
- Estimated Expiration
- 2043-11-27
AI Technical Summary
[0009]虽然已经有固体电解质型丙酮传感器得到报道，但在检出限、检出范围、稳定性等方面仍有进一步提升的空间，以提高传感器的检测精度、推动呼吸检测和环境检测的窗口前移
[0024]（1）使用Gd2Zr2O7固体电解质构筑了丙酮传感器，该种类型的固体电解质有利于在较低温度下获得高电导率，扩展了固体电解质型丙酮传感器的种类。
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Figure CN117589838B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of gas sensor technology, specifically relating to an acetone sensor based on Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode and its preparation method. Background Technology
[0002] With the continuous development of gas sensor technology, it has shown increasingly important application prospects in fields such as environmental monitoring and medical diagnosis. Diabetes is gradually becoming an unprecedented global epidemic, and diabetic patients face the risk of developing ketosis, a complication that causes greater damage to the body. Currently, the detection of diabetes and ketosis mainly relies on the detection of blood glucose or blood ketones. In recent years, the gradually developing gas detection technology has the potential to replace traditional diagnostic methods, achieving completely painless and non-invasive diagnosis. Numerous studies have demonstrated that the acetone content in the exhaled breath of diabetic patients is higher than that of healthy individuals, and is highly correlated with blood ketone concentration. The acetone content in the breath of healthy individuals is approximately 0.3~0.9 ppm, while that in diabetic patients typically exceeds 1.8 ppm. Therefore, the detection of acetone concentration in exhaled breath is an effective method for monitoring diabetes and blood ketone concentration.
[0003] For gas detection technology, gas sensors are best suited for efficient detection and widespread application due to their miniaturization and real-time detection capabilities. However, the complex composition and high humidity of exhaled gas make developing gas sensors with high sensitivity, selectivity, and stability a significant challenge. Solid electrolyte gas sensors are the optimal choice due to their unparalleled stability and selectivity compared to other types of sensors.
[0004] Solid electrolyte sensors typically consist of a solid electrolyte, a sensitive electrode, and a reference electrode. Their sensing process and sensing mechanism can be explained by the mixed potential theory. Unlike equilibrium potential sensors where the electrochemical oxidation and reduction reactions are a pair of reversible reactions, in the sensing process of a mixed potential gas sensor, in addition to the heterogeneous catalytic reaction inside the electrode layer (reaction (1)), the electrochemical reactions (2) and (3) of O2 and acetone gas occur simultaneously at the electrode / electrolyte / gas interface (three-phase boundary, TPB). When the reaction rates of reactions (2) and (3) are equal, the reaction reaches equilibrium, and the potential formed on the electrode at this time is the mixed potential. The potential difference between the sensitive electrode and the reference electrode serves as the sensor's detection signal V. The difference between this detection signal in the gas to be measured and in air is defined as the sensor's response value ΔV. Therefore, the sensor's response magnitude is jointly determined by the heterogeneous catalytic reaction and the electrochemical reaction, which is closely related to the electrochemical activity, chemical catalytic activity, microstructure of the sensitive electrode material, and the composition and reactive sites of the three-phase interface.
[0005] The reaction formula is:
[0006] C3H6O + 4O2 = 3CO2 + 3H2O (1)
[0007] O2+4e - =2O 2- (2)
[0008] C3H6O+8O 2- =3CO2 + 3H2O + 16e - (3)
[0009] Although solid electrolyte acetone sensors have been reported, there is still room for improvement in detection limits, detection ranges, and stability to enhance detection accuracy and advance the detection window for respiratory and environmental monitoring. From the perspective of the composition, structure, and sensing mechanism of solid electrolyte sensors, the strategies for developing solid electrolyte gas sensors mainly include broadening the types of solid electrolytes, designing and developing high-performance oxide sensitive electrode materials, and constructing efficient three-phase reaction interfaces. This invention, based on the novel pyrochlore-structured solid electrolyte Gd₂Zr₂O₇, developed a CoSb₂O₆ sensitive electrode to achieve effective detection of ultra-low concentrations of acetone. Summary of the Invention
[0010] This invention provides an acetone sensor based on a Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode and its preparation method. The prepared sensor has good sensitivity to acetone, including an extremely low detection limit, an extremely wide linear detection range, good selectivity and stability.
[0011] The acetone sensor based on Gd₂Zr₂O₇ solid electrolyte described in this invention is constructed using pyrochlore-type solid electrolyte Gd₂Zr₂O₇ as the ion-conducting layer, Pt as the reference electrode, and CoSb₂O₆ with high electrochemical catalytic activity as the sensitive electrode. Its structure is as follows: Figure 1 As shown, the sensor has a layered structure, consisting of, from top to bottom, a CoSb₂O₆ sensitive electrode, a Pt reference electrode, a Gd₂Zr₂O₇ solid electrolyte substrate, an inorganic binder, and an Al₂O₃ ceramic plate with a Pt heating electrode. Both the CoSb₂O₆ sensitive electrode and the Pt reference electrode are strip-shaped structures, symmetrically fabricated on both sides of the upper surface of the Gd₂Zr₂O₇ solid electrolyte substrate. The lower surface of the Gd₂Zr₂O₇ electrolyte substrate is bonded to the Al₂O₃ ceramic plate with the Pt heating electrode using an inorganic binder. The sensor described in this invention exhibits good sensitivity to acetone, achieving linear detection of acetone from 10 ppb to 100 ppm.
[0012] The present invention discloses a method for preparing an acetone sensor based on a Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode, the steps of which are as follows:
[0013] A. Preparation of electrolyte substrate
[0014] The electrolyte material was prepared by a hydrothermal method. 5 mmol of Gd(NO3)3·6H2O, 5 mmol of ZrOCl2·8H2O, and 25 mmol of urea (precipitant) were sequentially dissolved in 30–50 mL of deionized water and stirred for 20–40 min. The solution was then transferred to a 100 mL polytetrafluoroethylene reactor and reacted at 170–190 °C for 20–28 h. The white precipitate was collected and washed alternately with deionized water and ethanol, centrifuged, and dried. The resulting powder was pre-sintered at 500–700 °C for 3–5 h to remove moisture and organic impurities, and then pressed into discs under a pressure of 280–300 MPa. Finally, it was sintered at 1500–1600 °C for 3–5 h to obtain the Gd2Zr2O7 solid electrolyte, which was then cut to obtain the electrolyte substrate.
[0015] B. Preparation of CoSb2O6 Sensitive Electrode Material
[0016] 3 mmol of SbCl3 and 1.5 mmol of CoCl2∙2H2O were dissolved in ethanol to obtain a precursor solution with a concentration of 0.1 mol / L. The two precursor solutions were mixed, and 8-12 mL of polyethylene glycol (PEG) was added dropwise at 70-90 °C and stirred for 2-4 h. Then, ammonia was added dropwise to the solution until the pH of the solution was 7-9, and the mixture was stirred at 70-90 °C for another 6-8 h to form a gel. The gel was pre-sintered at 200-300 °C for 2-4 h, and finally sintered at 700-900 °C for 4-6 h to obtain the CoSb2O6 sensitive electrode material.
[0017] C. Sensor fabrication
[0018] A reference electrode and a sensing electrode were fabricated on a Gd₂Zr₂O₇ solid electrolyte substrate. Then, an inorganic binder was prepared to adhere an Al₂O₃ ceramic plate with a Pt heating electrode to the lower surface of the electrolyte substrate. Specific steps included:
[0019] (1) Fabrication of Pt reference electrode: A 5-10 μm thick Pt paste is brushed onto one side of the upper surface of the Gd2Zr2O7 solid electrolyte substrate obtained in step A. At the same time, two Pt wires are folded in half. One Pt wire is glued to the middle position of the reference electrode with Pt paste as a reference electrode lead, and the other Pt wire is glued to the other end of the upper surface of the Gd2Zr2O7 solid electrolyte substrate as a sensitive electrode lead. The Gd2Zr2O7 solid electrolyte substrate is baked at 90-120℃ for 20-40 min, and then sintered at 900-1100℃ for 20-40 min to remove the organic solvent in the Pt paste. At the same time, the Pt paste is solidified to ensure good contact between the reference electrode, the lead and the electrolyte substrate. Finally, it is cooled to room temperature.
[0020] (2) Fabrication of CoSb2O6 sensitive electrode: The CoSb2O6 sensitive electrode material obtained in step B is mixed with deionized water to prepare a viscous CoSb2O6 slurry; a 60~80μm thick sensitive electrode is prepared on one side of the sensitive electrode lead of the Gd2Zr2O7 solid electrolyte substrate in step (1) by using a brush to dip the CoSb2O6 slurry; then the electrolyte substrate is placed in a muffle furnace and heated to 700~900℃ at a heating rate of 1.5~3.0℃ / min, and sintered for 2~3h to ensure close contact between the sensitive electrode and the electrolyte;
[0021] (3) Bonding Al2O3 ceramic plate with Pt heating electrode: First, mix 2~4 mL of Na2SiO3·9H2O with 0.7~1.0 g of Al2O3 powder and stir evenly to prepare an inorganic binder; prepare an “M” shaped Pt heating electrode by screen printing on Al2O3 ceramic plate; use the prepared inorganic binder to bond the Al2O3 ceramic plate with Pt heating electrode to the lower surface of solid electrolyte substrate and make the Pt heating electrode contact the lower surface of solid electrolyte substrate.
[0022] (4) The device obtained in step (3) is welded and packaged to obtain the acetone sensor based on Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode as described in this invention.
[0023] Advantages of this invention:
[0024] (1) An acetone sensor was constructed using Gd2Zr2O7 solid electrolyte. This type of solid electrolyte is advantageous for obtaining high conductivity at lower temperatures, thus expanding the types of solid electrolyte acetone sensors.
[0025] (2) A CoSb2O6 sensitive electrode material was prepared, which has high electrochemical catalytic activity for acetone.
[0026] (3) For the first time, a Gd2Zr2O7 solid electrolyte-based acetone sensor was constructed using CoSb2O6 sensitive electrode material, realizing ultra-low concentration detection and extremely wide-range linear detection of acetone gas by a solid electrolyte gas sensor. Attached Figure Description
[0027] Figure 1 : A schematic diagram of the structure of the acetone sensor based on Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode as described in this invention;
[0028] Component names: 1. Gd2Zr2O7 solid electrolyte substrate; 2. Pt reference electrode; 3. CoSb2O6 sensitive electrode; 4. Pt wire; 5. Inorganic binder; 6. Pt heating electrode; 7. Al2O3 ceramic plate.
[0029] Figure 2 XRD pattern and Raman spectrum of the Gd2Zr2O7 solid electrolyte prepared in this invention;
[0030] like Figure 2 As shown in (a), the XRD pattern of the Gd2Zr2O7 solid electrolyte prepared in this invention is as follows. Figure 2 (b) shows the Raman spectrum of the Gd2Zr2O7 solid electrolyte prepared in this invention; by observing and calibrating the characteristic peaks, it can be determined that the prepared Gd2Zr2O7 solid electrolyte material has a pyrochlore-type structure.
[0031] Figure 3 XRD pattern and Raman spectrum of the CoSb2O6 sensitive material prepared in this invention;
[0032] like Figure 3 As shown in (a), the XRD pattern of the CoSb₂O₆ sensitive material is as follows. The main diffraction peaks are consistent with those on the standard card JCPDS#18-403, indicating that the sensitive electrode material prepared in this invention is mainly CoSb₂O₆. However, CoSb₂O₆-related peaks were observed at positions 17.9° and 36.8°. 2.33 Sb 0.67 The diffraction peaks of O4 indicate that Co 2.33 Sb 0.67 The presence of the O4 phase; such as Figure 3 (b) shows the Raman spectrum of the CoSb2O6 sensitive material, with the 505 cm⁻¹ value shown. -1 641cm -1 and 710cm -1 The peak at that position corresponds to CoSb2O6.
[0033] Figure 4 : Surface SEM images and cross-sectional SEM images of the CoSb2O6 sensitive electrode prepared in this invention;
[0034] like Figure 4 As shown in (a), the surface SEM image of the sensitive electrode reveals that the CoSb₂O₆ sensing material is composed of irregular micro- and nanoparticles, forming numerous channels on its surface, exhibiting a loose and porous structure that facilitates the migration and diffusion of gas molecules within the sensitive electrode layer; Figure 4 (b) shows a cross-sectional SEM image of the sensitive electrode, which shows that the thickness of the sensitive electrode layer is approximately 70.2 μm.
[0035] Figure 5 The continuous response curve (a) and the relationship curve between the response value and the acetone concentration (b) of the acetone sensor based on Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode prepared in this invention at 560℃.
[0036] like Figure 5 (a) shows the continuous response recovery curves of the prepared acetone sensor based on Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode to 10ppb~100ppm acetone. It can be seen that the sensor has good response recovery characteristics to 10ppb~100ppm acetone. Figure 5 (b) shows the relationship between the sensor's response value (defined as the difference between the device's potential value in acetone gas of different concentrations and its potential value in air, which is measured by a Fluke 8846A digital multimeter connected between the two electrodes of the sensor) and the acetone concentration. The sensor's response values to different concentrations of acetone are listed in Table 1. It can be seen that the response value and the concentration have a logarithmic linear relationship, and the slope (defined as the sensor's sensitivity) is -32.4 mV / decade.
[0037] Figure 6 Selectivity histograms for a single gas and for a mixed gas of an acetone sensor based on a Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode at 560 °C.
[0038] like Figure 6 As shown in (a), this is a schematic diagram of the selectivity of the acetone sensor based on Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode prepared in this invention at an operating temperature of 560℃. It can be seen that for a single gas, the sensor's response to 0.1ppm and 50ppm acetone is much higher than that to other gases; Figure 6As shown in (b), this is a histogram illustrating the selectivity of the acetone sensor based on a Gd₂Zr₂O₇ solid electrolyte with CoSb₂O₆ as the sensitive electrode, prepared according to the present invention, to a mixed gas at an operating temperature of 560°C. It can be seen that for a mixed gas of 0.5 ppm acetone and other interfering gases, the sensor's response value is less affected by other components compared to 0.5 ppm pure acetone. These results demonstrate that the sensor exhibits excellent selectivity. Detailed Implementation
[0039] Example 1:
[0040] The CoSb₂O₆ sensitive electrode material was prepared, a planar sensor was fabricated on a Gd₂Zr₂O₇ solid electrolyte substrate, and its gas-sensing performance was tested. The specific process is as follows:
[0041] 1. Preparation of Gd₂Zr₂O₇ solid electrolyte substrate: 5 mmol of Gd(NO₃)₃·6H₂O, 5 mmol of ZrOCl₂·8H₂O, and 25 mmol of urea (as a precipitant) were dissolved in 40 mL of deionized water and stirred for 30 min. After the solution was completely mixed, it was transferred to a 100 mL polytetrafluoroethylene reactor and placed in an oven. The reactor was reacted at 180 °C for 24 h. The precipitate obtained from the reaction was collected, washed alternately with deionized water and ethanol, centrifuged, and dried. The resulting powder was pre-sintered at 600 °C for 4 h to ensure thorough drying and remove impurities. Then, it was formed into a disc with a certain diameter and thickness under a pressure of 290 MPa. The disc was then sintered at 1550 °C for 4 h to obtain an electrolyte plate. Finally, the obtained electrolyte plate was cut into thin-film electrolyte substrates with certain geometric dimensions (2 mm long × 2 mm wide × 0.3 mm thick) for sensor fabrication.
[0042] 2. Fabrication of Pt reference electrode: A 0.5mm × 2mm, 8μm thick Pt reference electrode was fabricated on one side of the upper surface of the Gd2Zr2O7 solid electrolyte substrate obtained in step 1 using Pt paste. At the same time, two Pt wires were folded in half. One wire was attached to the middle of the reference electrode with Pt paste as a reference electrode lead, and the other wire was attached to the other end of the upper surface of the electrolyte substrate as a sensitive electrode lead. The electrolyte substrate was then baked at 110℃ for 30min, and then sintered at 1000℃ for 30min to remove the organic solvent in the Pt paste and to solidify the Pt paste to ensure good contact between the reference electrode, the lead, and the electrolyte substrate. Finally, the substrate was cooled to room temperature.
[0043] 3. Fabrication of the CoSb₂O₆ sensitive electrode: 3 mmol of SbCl₃ and 1.5 mmol of CoCl₂∙2H₂O were dissolved in 30 mL of ethanol and 15 mL of ethanol, respectively, to obtain precursor solutions. The two precursor solutions were mixed, and 10 mL of polyethylene glycol (PEG) was added dropwise at 80 °C with stirring for 3 h. Then, ammonia was added dropwise to the solution until the pH reached 8, and stirring was continued at 80 °C for 7 h to form a gel. The collected gel was pre-sintered at 250 °C for 3 h, and finally sintered at 800 °C for 5 h to obtain the CoSb₂O₆ sensitive material.
[0044] Take an appropriate amount of powdered CoSb2O6 sensitive electrode material and mix it with deionized water to prepare a slurry with a certain viscosity. Use a brush to dip the slurry and coat a 0.5mm×2mm thick sensitive electrode on one side of the sensitive electrode lead prepared in step 2, so that it completely covers the junction between the sensitive electrode lead and the electrolyte substrate.
[0045] The prepared electrolyte substrate with reference and sensitive electrodes was placed in a muffle furnace and heated to 800°C at a heating rate of 2.0°C / min and held for 2.5 hours before being cooled to room temperature.
[0046] 4. Bonding the ceramic plate with heating electrodes: First, an inorganic adhesive is prepared using Al2O3 and Na2SiO3·9H2O (water glass) in a mass ratio of 5:1. The lower surface of the electrolyte substrate (the side without electrodes) is then bonded to an Al2O3 ceramic plate of the same size (2mm x 2mm, 0.2mm thick) with “M”-shaped Pt heating electrodes using the inorganic adhesive.
[0047] 5. Device soldering and packaging. The device is soldered onto a hexagonal socket, covered with a protective cover, and the acetone sensor based on Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode is completed.
[0048] 6. Gas-sensing test of the fabricated device: An ammeter was connected to both ends of an Al2O3 ceramic plate with a Pt heating electrode to control the sensor's operating temperature by controlling the current. The fabricated sensor was connected to a Fluke 8846A digital multimeter, with the sensitive electrode connected to the positive terminal of the multimeter and the reference electrode connected to the negative terminal. The sensor was placed in air, 10ppb acetone, 20ppb acetone, 50ppb acetone, 0.1ppm acetone, 0.2ppm acetone, 0.5ppm acetone, 1ppm acetone, 2ppm acetone, 5ppm acetone, 10ppm acetone, 20ppm acetone, 50ppm acetone, and 100ppm acetone gases to collect potential signals. The difference between the potential of the device in different concentrations of acetone and the potential in air was taken as the sensor's response value. The experimental results are shown in Table 1.
[0049] Table 1: Response data of the acetone sensor prepared in this invention to different concentrations of acetone at 560℃
[0050]
[0051] Table 1 shows the response values of the acetone sensor prepared in this invention to different concentrations of acetone at 560℃. Each concentration was tested three times. It can be seen that the sensor's response values to each concentration of acetone gas are very close in the three tests, indicating that the sensor has stable and reliable sensitivity. The sensor can detect acetone as low as 10 ppb with a response value of -7.9 mV, exhibiting an extremely low detection limit.
Claims
1. An acetone sensor based on Gd₂Zr₂O₇ solid electrolyte, characterized in that: It consists of a CoSb2O6 sensitive electrode, a Pt reference electrode, a Gd2Zr2O7 solid electrolyte substrate, and an Al2O3 ceramic plate with a Pt heating electrode. The CoSb2O6 sensitive electrode and the Pt reference electrode are both strip-shaped structures, symmetrically prepared on both sides of the upper surface of the Gd2Zr2O7 solid electrolyte substrate. The lower surface of the Gd2Zr2O7 electrolyte substrate is bonded to the Al2O3 ceramic plate with the Pt heating electrode by an inorganic adhesive, and the Pt heating electrode is in contact with the lower surface of the solid electrolyte substrate.
2. The acetone sensor based on Gd₂Zr₂O₇ solid electrolyte as described in claim 1, characterized in that: The process involves dissolving 5 mmol of Gd(NO3)3·6H2O, 5 mmol of ZrOCl2·8H2O, and 25 mmol of urea sequentially in 30-50 mL of deionized water and stirring for 20-40 min. The solution is then transferred to a 100 mL polytetrafluoroethylene reactor and reacted at 170-190 °C for 20-28 h. The white precipitate is collected and washed alternately with deionized water and ethanol, centrifuged, and dried. The resulting powder is pre-sintered at 500-700 °C for 3-5 h to remove moisture and organic impurities, and then pressed into discs under a pressure of 280-300 MPa. Finally, the solid electrolyte Gd2Zr2O7 is obtained by sintering at 1500-1600 °C for 3-5 h, and the electrolyte substrate is obtained by cutting.
3. The acetone sensor based on Gd₂Zr₂O₇ solid electrolyte as described in claim 1, characterized in that: 3 mmol of SbCl3 and 1.5 mmol of CoCl2∙2H2O were dissolved in ethanol to obtain a precursor solution with a concentration of 0.1 mol / L. The two precursor solutions were mixed, and 8-12 mL of polyethylene glycol was added dropwise at 70-90 °C and stirred for 2-4 h. Then, ammonia was added dropwise to the solution until the pH of the solution was 7-9, and stirring was continued at 70-90 °C for 6-8 h to form a gel. The gel was pre-sintered at 200-300 °C for 2-4 h, and finally sintered at 700-900 °C for 4-6 h to obtain the CoSb2O6 sensitive electrode material.
4. A method for preparing an acetone sensor based on a Gd₂Zr₂O₇ solid electrolyte as described in any one of claims 1 to 3, comprising the following steps: (1) Fabrication of Pt reference electrode: A 5-10 μm thick Pt paste is brushed onto one side of the upper surface of the Gd2Zr2O7 solid electrolyte substrate. At the same time, two Pt wires are folded in half. One Pt wire is glued to the middle position of the reference electrode with Pt paste as a reference electrode lead, and the other Pt wire is glued to the other end of the upper surface of the Gd2Zr2O7 solid electrolyte substrate as a sensitive electrode lead. The Gd2Zr2O7 solid electrolyte substrate is baked at 90-120℃ for 20-40 min, then sintered at 900-1100℃ for 20-40 min, and finally cooled to room temperature. (2) Fabrication of CoSb2O6 sensitive electrode: CoSb2O6 sensitive electrode material is mixed with deionized water to prepare a viscous CoSb2O6 slurry; a 60~80μm thick sensitive electrode is prepared on one side of the sensitive electrode lead of the Gd2Zr2O7 solid electrolyte substrate in step (1) by using a brush to dip the CoSb2O6 slurry; then the electrolyte substrate is heated to 700~900℃ at a heating rate of 1.5~3.0℃ / min and sintered for 2~3h. (3) Bonding Al2O3 ceramic plate with Pt heating electrode: First, mix 2~4 mL of Na2SiO3·9H2O with 0.7~1.0 g of Al2O3 powder and stir evenly to prepare an inorganic binder; prepare Pt heating electrode by screen printing on Al2O3 ceramic plate; use the prepared inorganic binder to bond Al2O3 ceramic plate with Pt heating electrode to the lower surface of solid electrolyte substrate and make Pt heating electrode contact with the lower surface of solid electrolyte substrate. (4) The device obtained in step (3) is welded and packaged to obtain an acetone sensor based on Gd2Zr2O7 solid electrolyte with CoSb2O6 as the sensitive electrode.