A phenol gas sensor and a preparation method and application thereof

Abstract

The present application relates to a kind of phenol gas sensor and its preparation method and application, sensor includes counter electrode (1), reference electrode (2), sensitive electrode (3), YSZ solid electrolyte layer (4) and heating sheet (5);The lower surface of the YSZ solid electrolyte layer (4) is attached heating sheet (5), the upper surface is spaced apart and provided with counter electrode (1), reference electrode (2) and sensitive electrode (3), the material of the sensitive electrode (3) is chromium oxide.Compared with prior art, the present application provides a kind of portable electrochemical sensor and its preparation method, can realize the high selectivity detection of phenol gas.

Description

Technical Field

[0001] This invention relates to the field of electrochemical gas sensor technology, and in particular to a phenol gas sensor, its preparation method, and its application. Background Technology

[0002] Phenol (chemical formula: C6H5OH), also known as carbolic acid, is a colorless, needle-like crystal with a characteristic odor. It is toxic and primarily used in the production of phenolic resins, caprolactam, bisphenol A, adipic acid, aniline, alkylphenols, and salicylic acid. It is also used as a solvent, reagent, and disinfectant, and has wide applications in synthetic fibers, synthetic rubber, plastics, pharmaceuticals, pesticides, fragrances, dyes, and coatings. Phenol has a freezing point of 40.6℃ and forms colorless, needle-like crystals at room temperature. It is slightly soluble in water, liquefies when mixed with approximately 8% water, and is miscible with water above 65℃. It is readily soluble in organic solvents and miscible with ether, chloroform, glycerol, carbon disulfide, petrolatum, volatile oils, and strong alkaline aqueous solutions.

[0003] Phenol is extremely corrosive; contact with it causes local protein denaturation and has a strong corrosive effect on the skin and mucous membranes. It is highly toxic, capable of inhibiting the central nervous system or damaging liver and kidney function. Inhalation of high concentrations of phenol gas can lead to dizziness, headache, fatigue, blurred vision, and pulmonary edema. Ingestion can cause burns and gastrointestinal perforation, and in severe cases, kidney and respiratory failure. Phenol is an endocrine disruptor that promotes the activation and proliferation of cancer cells. It exhibits significant interference effects on animal estrogen, thyroid hormones, and catecholamines, potentially leading to reproductive disorders, developmental abnormalities, cancer, and complex ecological effects in humans. Phenol in the air enters the human body through respiration and skin contact, causing protein denaturation and precipitation, and damaging and inhibiting the mucous membranes, cardiovascular system, and central nervous system.

[0004] Phenol waste gas entering water bodies can negatively impact the physiological functions of aquatic organisms and crops. Phenol is non-volatile and can persist in soil and aquatic environments for extended periods, causing serious environmental pollution. When the phenol content in water reaches 0.1002 mg / L, a phenolic odor will be produced during chlorination, affecting the quality of drinking water sources: concentrations greater than 0.1005 mg / L make it unsuitable for drinking; concentrations greater than 0.11 mg / L will cause fish to have an unpleasant odor and become inedible; concentrations greater than 1 mg / L will severely impact fish reproduction and other activities; and when the phenol content exceeds 10 mg / L, fish and other aquatic organisms cannot survive. Furthermore, the toxicity of phenol significantly inhibits the growth rate of aquatic microorganisms (such as algae, bacteria, and mollusks), affecting the ecological balance of the water. Direct irrigation of farmland with wastewater containing phenol concentrations exceeding 100 mg / L will cause crops to wither and yields to decrease.

[0005] Currently, the main methods for detecting phenol gas include chromatography, spectrometry, and immunoassay. However, these methods are expensive, cumbersome, require professional personnel, and are time-consuming. Therefore, designing a phenol gas sensor that is simple to prepare, low in cost, highly selective, highly sensitive, and has a low detection limit is of great clinical significance. Summary of the Invention

[0006] The purpose of this invention is to provide a phenol gas sensor, its preparation method, and its application, so as to achieve highly selective detection of phenol gas.

[0007] The objective of this invention can be achieved through the following technical solution: a phenol gas sensor, comprising a counter electrode, a reference electrode, a sensitive electrode, a YSZ solid electrolyte layer, and a heating element;

[0008] The YSZ (yttrium-stabilized zirconium oxide) solid electrolyte layer has a heating element attached to its lower surface and a counter electrode, a reference electrode, and a sensitive electrode spaced apart on its upper surface. The sensitive electrode is made of chromium oxide.

[0009] Preferably, a counter electrode, a reference electrode, and a sensitive electrode are disposed at intervals on the YSZ solid electrolyte layer.

[0010] Preferably, the heating element is made of aluminum oxide, the counter electrode is made of Pt, and the reference electrode is made of manganese dioxide.

[0011] Preferably, the YSZ solid electrolyte layer and the heating element are both cuboid in shape, and the length and width of the YSZ solid electrolyte layer are equal to the length and width of the heating element. The counter electrode, the reference electrode, and the sensitive electrode are all cuboids of the same size. The counter electrode is provided with a counter electrode lead, the reference electrode is provided with a reference electrode lead, and the sensitive electrode is provided with a sensitive electrode lead.

[0012] Preferably, the length of the YSZ solid electrolyte layer and the heating element ranges from 2cm to 3cm, and the width ranges from 1.3cm to 1.7cm; the thickness of the YSZ solid electrolyte layer ranges from 0.5cm to 1cm, and the thickness of the heating element ranges from 1.1mm to 1.5mm.

[0013] Preferably, the length of the counter electrode, reference electrode, and sensitive electrode ranges from 2 mm to 3 mm, the width ranges from 2 mm to 3 mm, and the thickness ranges from 14 μm to 16 μm.

[0014] A method for preparing the above-mentioned phenol gas sensor includes the following steps:

[0015] S1: Pt paste is printed onto the upper surface of the YSZ solid electrolyte layer using screen printing, and then dried and sintered to form the counter electrode.

[0016] S2: A paste containing manganese dioxide is printed onto the upper surface of the YSZ solid electrolyte layer using screen printing, and then dried and sintered to form a reference electrode.

[0017] S3: A paste containing chromium oxide is printed onto the upper surface of the YSZ solid electrolyte layer using screen printing, and then dried to form a sensitive electrode;

[0018] S4: Pt paste is applied to the surfaces of the counter electrode, reference electrode, and sensitive electrode respectively. Then, the counter electrode lead, reference electrode lead, and sensitive electrode lead are drawn out through the Pt paste. After drying, they are sintered into shape.

[0019] S5: Place the heating element under the YSZ solid electrolyte layer, and then bond the heating element and the YSZ solid electrolyte layer together with a high-temperature resistant adhesive. The sensor fabrication is now complete.

[0020] Preferably, during the sintering process described in step S3, the sintering temperature is 1000~1300℃.

[0021] More preferably, in the sintering process described in step S3, the sintering temperature is 1050~1200℃.

[0022] More preferably, in the sintering process described in step S3, the sintering temperature is 1100℃.

[0023] Preferably, the preparation method of the manganese dioxide-containing slurry in step S2 is as follows: manganese dioxide powder and terpineol slurry are mixed and ground evenly in an agate mortar to obtain a manganese dioxide-containing slurry, wherein the terpineol slurry is prepared by mixing terpineol and ethyl cellulose.

[0024] Preferably, the preparation method of the chromium oxide-containing slurry in step S3 is as follows: chromium oxide and terpineol slurry are mixed and ground evenly in an agate mortar to obtain a chromium oxide-containing slurry, wherein the terpineol slurry is prepared by mixing terpineol and ethyl cellulose.

[0025] An application of the above-mentioned phenol gas sensor is to use the sensor for the detection of phenol gas in a mixed gas.

[0026] Gas sensors based on yttria-stabilized zirconia (YSZ or zirconium-based) electrolytes have attracted widespread attention due to their applicability to extreme environments (high temperature, high humidity) and their relatively high selectivity and low cost. Among them, zirconium-based gas sensors equipped with oxide-sensitive electrodes have been the most extensively studied. However, there are currently no reports on the high-selectivity detection of phenol gas by such zirconium-based sensors. This invention proposes for the first time a zirconium-based sensor with a high-selectivity response to phenol gas.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention provides a portable electrochemical sensor and its preparation method, which can achieve highly selective detection of phenol gas;

[0029] 2. This invention is a three-electrode system that can convert chemical signals into electrical signals, exhibiting good sensitivity and sensing effect. It also demonstrates good responsiveness and stability to changes in current. The electrochemical sensor of this invention has high testing accuracy and advantages such as strong selectivity, high sensitivity, and good accuracy.

[0030] 3. The three-electrode system design of this invention provides a bias voltage to the sensor, which enhances the reactivity of phenol gas, causing it to undergo oxidation or reduction reactions and improving the selectivity of phenol gas;

[0031] 4. This invention requires only one sensitive electrode and does not require optical coupling or complex algorithms to achieve high selectivity for phenol gas;

[0032] 5. This invention utilizes YSZ as an ion-conducting layer and chromium oxide material with high electrochemical catalytic activity as a sensitive electrode. By changing the microstructure of the sensitive electrode layer through different sintering temperatures (1050℃~1200℃), sensitive electrode layers with different pore structures are obtained, thus optimizing the microstructure of the sensitive electrode and facilitating the rapid arrival of the gas to be measured at the three-phase interface to participate in the electrochemical reaction, thereby improving the high selectivity and sensitivity of the sensor to phenol gas.

[0033] 6. Chromium oxide sintered at different temperatures has different microstructures and different responses to phenol gas and other interfering gases. In this invention, after sintering the slurry containing chromium oxide at a high temperature of 1100℃, the structure of chromium oxide is conducive to the rapid diffusion of phenol gas, providing more reaction sites for phenol gas. Therefore, the response to phenol gas is particularly prominent and has obvious selectivity.

[0034] 7. The sensor of this invention has a simple structure, is easy to operate, and is inexpensive and portable. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the sensor structure of the present invention;

[0036] Figure 2 The response curve of the sensor's sensitive electrode when the sintering temperature of the sensitive electrode is 1050℃;

[0037] Figure 3 The response curve of the sensor's sensitive electrode when the sintering temperature of the sensitive electrode is 1100℃;

[0038] Figure 4 The response curve of the sensor's sensitive electrode when the sintering temperature of the sensitive electrode is 1200℃;

[0039] Figure 5 The response step curves of the sensor's sensitive electrode to different concentrations of phenol when the sintering temperature of the sensitive electrode is 1100℃;

[0040] In the figure: 1-counter electrode, 2-reference electrode, 3-sensitive electrode, 4-YSZ solid electrolyte layer, 5-heating plate. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0042] Example 1

[0043] like Figure 1 As shown, a phenol gas sensor includes a counter electrode 1, a reference electrode 2, a sensitive electrode 3, a YSZ solid electrolyte layer 4, and a heating element 5. Both the YSZ solid electrolyte layer 4 and the heating element 5 are cuboids, with the side lengths of the YSZ solid electrolyte layer 4 and the heating element 5 being equal. The lower end face of the YSZ solid electrolyte layer 4 is attached to and fixedly connected to the upper end face of the heating element 5. The counter electrode 1, reference electrode 2, and sensitive electrode 3 are all cuboids of the same size, spaced apart on the upper end face of the YSZ solid electrolyte layer 4. The lower end faces of the counter electrode 1, reference electrode 2, and sensitive electrode 3 are respectively attached to and fixedly connected to the upper end face of the YSZ solid electrolyte layer 4. The material of the counter electrode 1 is Pt, the material of the reference electrode 2 is manganese dioxide, and the material of the sensitive electrode 3 is chromium oxide. Counter electrode 1 is provided with a counter electrode lead, reference electrode 2 is provided with a reference electrode lead, and sensitive electrode 3 is provided with a sensitive electrode lead; the preparation method specifically includes the following steps:

[0044] (1) Prepare YSZ solid electrolyte layer 4 and heating element 5 of the corresponding size according to the design size requirements;

[0045] (2) Prepare a terpineol slurry by mixing terpineol and ethyl cellulose in a mass ratio of 94:6;

[0046] (3) The first paste (Pt paste) is printed on the upper end of the YSZ solid electrolyte layer 4 at the designed position of the electrode 1 according to the design size using screen printing technology to obtain the prototype of the electrode 1.

[0047] (4) Mix manganese dioxide powder and terpineol slurry in an agate mortar at a mass ratio of 1:1.5 and grind them evenly to form a second slurry;

[0048] (5) The second paste is printed on the reference electrode 2 at the designed position on the upper end face of the YSZ solid electrolyte layer 4 according to the designed size using screen printing technology to obtain the prototype of the reference electrode 2;

[0049] (6) Place the product obtained from steps (3) and (5) into a drying oven and dry it at 130°C. o Dry at C for 12 hours, then place in a sintering furnace at 1400°C. o After sintering at C for 2 hours and cooling to room temperature, counter electrode 1 and reference electrode 2 are formed on the upper surface of YSZ solid electrolyte layer 4.

[0050] (7) Chromium oxide and terpineol slurry are mixed and ground evenly in an agate mortar at a mass ratio of 1:1 to form a third slurry;

[0051] (8) The third paste is printed on the upper end face of the YSZ solid electrolyte layer 4 at the designed position of the sensitive electrode 3 according to the design size using screen printing technology to obtain the prototype of the sensitive electrode 3;

[0052] (9) Place the product obtained after step (8) into a drying oven, set the temperature of the drying oven to 130℃ and dry for 12 hours, then place it in a sintering furnace and dry at 1100℃. o After sintering at C for 2 hours and cooling to room temperature, a sensitive electrode 3 is formed on the upper surface of the YSZ solid electrolyte layer 4.

[0053] (10) Pt paste is applied to the surfaces of counter electrode 1, reference electrode 2 and sensitive electrode 3 respectively, and then counter electrode lead wire, reference electrode lead wire and sensitive electrode lead wire are drawn out through Pt paste respectively;

[0054] (11) Place the product obtained after step (10) into a drying oven and dry it at 130°C for 12 hours. Then take it out and place it in a sintering furnace and sinter it at 900°C for 2 hours to form the product. Take it out and cool it to room temperature.

[0055] (12) Place the heating element 5 under the YSZ solid electrolyte layer 4 in the product obtained after step (11), and bond the heating element 5 and the YSZ solid electrolyte layer 4 together with a high-temperature resistant adhesive. The sensor preparation is complete.

[0056] Example 2

[0057] A phenol gas sensor, wherein the heating element 5 is made of alumina, and the length of the YSZ solid electrolyte layer 4 is [missing information]. lcm, the width of YSZ solid electrolyte layer 4 is d cm, the thickness of YSZ solid electrolyte layer 4 is h mm, the length of heating element 5 is l 1 cm, the width of heating element 5 is d 1 cm, the thickness of heating element 5 is h 1 mm, where l The value range is 2cm to 3cm. d The value range is 1.3cm to 1.7cm. h The value range is 0.5cm to 1cm. h The value of 1 ranges from 1.1 mm to 1.5 mm. l 1 = l , d 1 = d The lengths of electrode 1, reference electrode 2, and sensitive electrode 3 are respectively... l 2. The widths of the counter electrode 1, reference electrode 2, and sensitive electrode 3 are: d 2. The thicknesses of the counter electrode 1, reference electrode 2, and sensitive electrode 3 are: h 2, of which l The value of 2 ranges from 2mm to 3mm. d The value of 2 ranges from 2mm to 3mm. h The value of 2 ranges from 14µm to 16µm. The rest is the same as in Example 1.

[0058] After the sensor is fabricated, its performance is evaluated using a comprehensive testing platform, providing a basis for practical production applications. The sample gas is dynamically prepared and introduced into the testing device. In the sensor testing device, the quartz tube serves as the gas flow mechanism and is placed on an iron stand. The sensor's operating temperature is controlled by a 220V DC regulated power supply, a heating element, and a thermocouple. The sensor is placed in the quartz tube in close contact with the ceramic tube and the heating element. Platinum wire is inserted into the pores of the ceramic tube to ensure the sensor signal can be transmitted to an external signal source. A wooden plug is inserted into the ceramic tube, and after the quartz tube is connected, the gap between the ceramic and quartz tubes is filled with a wooden plug to ensure the test gas is in a sealed space. The testing process generally consists of the following steps:

[0059] 1) Place the prepared gas sensor in a quartz tube, seal the test chamber, and check the airtightness of the test chamber.

[0060] 2) Adjust the DC regulated power supply to provide a certain voltage to the heating element so that the sensor can work stably within a certain operating temperature range (400-450℃).

[0061] 3) A certain amount of background gas is introduced into the test chamber, and the signal is collected in real time by the electrochemical workstation. When the time-voltage curve is observed to be stable, it is determined that the sensor has entered a quasi-steady state. The target test gas is then introduced. When the introduced target gas makes the sensor signal stable and no longer changes significantly, the test chamber is replaced with background gas. After the sensor enters a stable state again, it is ready to perform the next measurement.

[0062] Figure 2 When the sintering temperature of the sensitive electrode is 1050℃, the electrochemical gas sensor of the present invention is used to test phenol (300ppb), acetone (1ppm), styrene (1ppm), hexanal (1ppm), ethanol (1ppm), n-butanol (1ppm), and ethylbenzene (1ppm) gases. The response curve of the sensitive electrode of the electrochemical gas sensor of the present invention is shown when the working voltage is 10.5V.

[0063] Figure 3 When the sintering temperature of the sensitive electrode is 1100℃, the electrochemical gas sensor of the present invention is used to test acetone (1ppm), styrene (1ppm), hexanal (1ppm), ethanol (1ppm), n-butanol (1ppm), ethylbenzene (1ppm), and phenol (300ppb) gases. The response curve of the sensitive electrode of the electrochemical gas sensor of the present invention is shown when the working voltage is 10.5V.

[0064] Figure 4 When the sintering temperature of the sensitive electrode is 1200℃, the electrochemical gas sensor of the present invention is used to test acetone (1ppm), styrene (1ppm), hexanal (1ppm), ethanol (1ppm), n-butanol (1ppm), ethylbenzene (1ppm), and phenol (300ppb) gases. The response curve of the sensitive electrode of the electrochemical gas sensor of the present invention to phenol gas is shown when the working voltage is 10.5V.

[0065] analyze Figure 2-4 It can be seen that after the sensitive material is uniformly printed on the surface of the YSZ solid electrolyte, when the sensor sintering temperature varies from 1050℃ to 1200℃, the electrochemical sensor of the present invention exhibits the best response to phenol at a sintering temperature of 1100℃. For example... Figure 5As shown, when the optimal sintering temperature (1100℃) of the sensitive electrode in the sensor of the present invention is used, tests are conducted on phenol gas of different concentrations (50ppb, 100ppb, 200ppb, 400ppb, 600ppb, 700ppb) with a working voltage of 10.5V. The response step curves of the sensitive electrode of the electrochemical gas sensor of the present invention to different concentrations of phenol are shown.

[0066] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a phenol gas sensor, characterized in that, The phenol gas sensor includes a counter electrode (1), a reference electrode (2), a sensitive electrode (3), a YSZ solid electrolyte layer (4), and a heating element (5). The lower surface of the YSZ solid electrolyte layer (4) is attached to a heating element (5), and the upper surface is provided with a counter electrode (1), a reference electrode (2) and a sensitive electrode (3) at intervals. The material of the sensitive electrode (3) is chromium oxide. The preparation method of the phenol gas sensor includes the following steps: S1: Pt paste is printed on the upper surface of YSZ solid electrolyte layer (4) by screen printing, and then dried and sintered to form counter electrode (1). S2: The paste containing manganese dioxide is printed on the upper surface of the YSZ solid electrolyte layer (4) by screen printing, and then sintered after drying to form a reference electrode (2). S3: The paste containing chromium oxide is printed onto the upper surface of the YSZ solid electrolyte layer (4) by screen printing and dried to form the sensitive electrode (3). S4: Pt paste is applied to the surfaces of counter electrode (1), reference electrode (2) and sensitive electrode (3) respectively, and then counter electrode lead wire, reference electrode lead wire and sensitive electrode lead wire are drawn out through Pt paste respectively, and sintered after drying; S5: Place the heating element (5) under the YSZ solid electrolyte layer (4), and bond the heating element (5) and the YSZ solid electrolyte layer (4) together with a high-temperature resistant adhesive. The sensor fabrication is now complete. The preparation method of the chromium oxide-containing slurry in step S3 is as follows: chromium oxide and terpineol slurry are mixed and ground evenly in an agate mortar to obtain a chromium oxide-containing slurry. The terpineol slurry is prepared by mixing terpineol and ethyl cellulose.

2. The method for preparing the phenol gas sensor according to claim 1, characterized in that, The YSZ solid electrolyte layer (4) is provided with a counter electrode (1), a reference electrode (2) and a sensitive electrode (3) at intervals.

3. The method for preparing the phenol gas sensor according to claim 1, characterized in that, The heating element (5) is made of aluminum oxide, the counter electrode (1) is made of platinum, and the reference electrode is made of manganese dioxide.

4. The method for preparing the phenol gas sensor according to claim 1, characterized in that, The YSZ solid electrolyte layer (4) and the heating element (5) are both cuboid in shape, and the length and width of the YSZ solid electrolyte layer (4) are equal to the length and width of the heating element (5). The counter electrode (1), the reference electrode (2) and the sensitive electrode (3) are all cuboids of the same size. The counter electrode (1) is provided with a counter electrode lead, the reference electrode (2) is provided with a reference electrode lead, and the sensitive electrode (3) is provided with a sensitive electrode lead.

5. The method for preparing the phenol gas sensor according to claim 1, characterized in that, The length of the YSZ solid electrolyte layer (4) and the heating element (5) ranges from 2cm to 3cm, and the width ranges from 1.3cm to 1.7cm; the thickness of the YSZ solid electrolyte layer (4) ranges from 0.5cm to 1cm, and the thickness of the heating element (5) ranges from 1.1mm to 1.5mm.

6. The method for preparing the phenol gas sensor according to claim 1, characterized in that, The length of the counter electrode (1), the reference electrode (2), and the sensitive electrode (3) ranges from 2 mm to 3 mm, the width ranges from 2 mm to 3 mm, and the thickness ranges from 14 μm to 16 μm.

7. The method for preparing the phenol gas sensor according to claim 1, characterized in that, In the sintering process described in step S4, the sintering temperature is 1000~1300℃.

8. A phenol gas sensor, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. An application of a phenol gas sensor prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The sensor was used to detect phenol gas in a gas mixture.

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