CN106940336B - Gas sensing material, preparation method thereof and gas sensor made of material - Google Patents
Gas sensing material, preparation method thereof and gas sensor made of material Download PDFInfo
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Abstract
The invention discloses a gas sensing material, a preparation method thereof and a gas sensor made of the material. The preparation method of the gas sensing material provided by the invention comprises the steps of performing biomimetic synthesis by taking a cation exchange membrane as a template, performing electrolytic deposition for 1-3 h at the temperature of 40-60 ℃, and taking an electrolytic deposition product in a cathode chamber to prepare the gas sensing material. The gas sensing material comprises hydroxyapatite which is tubular in microscopic appearance, 5-30 mu m in diameter and 10-100 mu m in length. The gas sensor made of the gas sensing material can effectively detect toxic and harmful gases at room temperature, and has the advantages of high response sensitivity, short response recovery time and low detection concentration. The preparation method of the gas sensing material is environment-friendly, simple in operation method, adjustable in raw material proportion and low in energy consumption.
Description
Technical Field
The invention belongs to the field of gas sensing materials, and particularly relates to a preparation method of a gas sensing material, the gas sensing material prepared by the method, and a gas sensor made of the material.
Background
Hydroxyapatite (Hydroxyapatite, chemical formula of Ca)10(PO4)6(OH)2Abbreviated HAp) is the major inorganic component of biological hard tissues such as natural bone and teeth. The HAp crystal is a hexagonal crystal system, a tunnel exists along a hexagonal axis, and Ca exists in the tunnel2+And OH-Easy to be Cd2+、Hg2+、Ba2+、Pd2+Substitution of plasma metal ions, Ca2+And the HAp can also perform exchange reaction with organic acid, protein, amino acid and the like containing carboxyl, so that the HAp can be used for preparing a sensor for detecting heavy metal ions, harmful metal ions, biological macromolecules and the like. The HAp crystal surface has multiple adsorption sites, namely a positively charged C site and a negatively charged P site, and shows excellent adsorption performance on substances with different charge properties, including gases. HAp has been widely used in chromatographic analysis and electrochemical detection, but has been studied as a gas sensing material. Study of HAp on CO, CO by R.U.Mene et al2The gas sensing performance of (2) shows that HAp is relative to CO and CO at about 165 DEG C2Has good sensing performance, and the mechanism is derived from the OH of the gas molecules and the surface of the HAp-Reaction to CO3 2-Into the lattice of the HAp, or vacancy-doped, resulting in a change in the HAp conductivity. HAp has excellent effect on gas moleculesThe HAp has poor conductivity and high operating temperature as a one-dimensional conductor, which greatly limits the application of the HAp in the field of gas sensing. By means of ion radiation technology (SHI) and doping Fe, Co and other elements, the physical property and crystal structure of HAp may be changed, including raising the electronegativity of material surface, forming new chemical bond, defect, etc. to make HAp to CO2The response sensitivity of gas sensing is improved, the operating temperature is reduced, but there is a gap from practical application. The research on the gas-sensitive performance of HAp to toxic and harmful gases under the room temperature condition is not reported so far.
Toxic and harmful gases present serious harm to global climate and natural environment, such as NH3Is a highly toxic atmospheric pollutant, causes discomfort to people even if the concentration in the atmosphere is only a few ppm, and contains 0.1-0.15% of NH3Can cause death and allows NH in industrial air3The maximum mass concentration is 0.01 mg/L; NH in soil3The vegetation can be poisoned and killed when reaching a certain concentration, and simultaneously NH3It can also severely corrode various equipment. At present, for NH3The gas-sensitive material for detection is mainly WO3Series, SnO2Series, ZnO semiconductors, ZnS, spinel type composite oxides Zn2SnO4Lanthanum ferrite oxide LaFeO3, polypyrrole, polyaniline and the like. However, the problems of high working temperature, long response recovery time and to-be-improved selectivity and responsiveness are generally existed. Although in recent years, there are also semiconductor composite materials such as CuO-SnO2，ZrO2-SnO2The like, Fe, Ce, Au, Ag and other noble metal elements, and by inorganic-organic matter and polypyrrole-WO3The composite method is widely used for improving the NH pair3The gas-sensitive properties of (a) still remain to be improved. In summary, a method capable of detecting trace concentration of NH at room temperature was developed3Gas sensing materials that are toxic, hazardous gases, and have high selectivity, fast response recovery, and low operating temperatures are highly desirable.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a preparation method of a gas sensing material, the gas sensing material prepared by the method and a gas sensor made of the material.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a preparation method of a gas sensing material comprises the following steps: (1) injecting a calcium-rubidium source mixed solution with the mole number of Rb element and the sum of the mole numbers of Rb element and Ca element (the mole percentage of Rb/(Rb + Ca) is 2.5-20%) into an anode chamber of an electrolytic cell, injecting a phosphorus source solution into a cathode chamber of the electrolytic cell according to the mole ratio of the sum of the mole numbers of Rb element and Ca element and the mole number of P element (the mole ratio of Rb + Ca)/P is 5/3, separating the anode chamber and the cathode chamber by a cation exchange membrane, and electrodepositing for 1-3 h under the conditions that the voltage is 3-9V and the temperature is 40-60 ℃; (2) removing the electrode, standing the electrolytic cell at the constant temperature of 25-50 ℃, supplementing a mixed solution of a calcium rubidium source and a phosphorus source solution during standing, and collecting an electrolytic deposition product on a cation exchange membrane at one side of the cathode chamber to obtain the gas sensing material.
The molar ratio of the hydroxyapatite is as follows: the calcium/phosphorus is equal to 5/3, and in order to keep the spatial structure of hydroxyapatite unchanged after adding rubidium element, the molar ratio of (calcium + rubidium)/phosphorus is 5/3, and the calcium rubidium source mixed solution and the phosphorus source solution are prepared and respectively injected into an anode chamber and a cathode chamber of the electrolytic cell.
Preferably, in the mixed solution of calcium and rubidium sources, the percentage of the sum of the mole number of the Rb element and the Ca element (the mole percentage of Rb/(Rb + Ca)) is 5% to 10%. This is because when the percentage of the sum of the number of moles of the Rb element and the Ca element is 10%, good response sensitivity is already achieved, and when it exceeds 10%, the yield of the gas sensing material is not high, which easily causes waste of the rubidium element, and further, the gas sensing effect is also reduced. When it exceeds 20%, the response sensitivity has been remarkably decreased as compared with 10%.
Further, the mixed solution of the calcium and the rubidium sources is prepared by the following method: uniformly dispersing 0.0125-0.25 mol/L rubidium salt solution into 0.3-1.0 mol/L calcium ion solution under the stirring condition to form the calcium-rubidium source mixed solution. Preferably, the magnetic stirring mode is adopted, so that time and labor are saved, and the stirring is more uniform.
Preferably, the calcium ion solution is selected from one or more of a calcium nitrate solution, a calcium acetate solution or a calcium chloride solution.
Preferably, the rubidium salt solution is selected from one or more of a rubidium nitrate solution, a rubidium chloride solution, and a rubidium carbonate solution.
Further, the phosphorus source solution is prepared by the following method: and adding a pH regulator into a phosphate solution with the concentration of 0.225-0.75 mol/L, and regulating the pH value of the solution to 10-12 to obtain the phosphorus source solution, wherein the higher pH value can meet the nucleation driving force for forming hydroxyapatite.
Preferably, the phosphate solution is one or more of ammonium dihydrogen phosphate solution, diammonium hydrogen phosphate solution, disodium hydrogen phosphate solution, sodium dihydrogen phosphate solution, potassium dihydrogen phosphate solution or dipotassium hydrogen phosphate solution; the pH regulator is selected from one of sodium hydroxide, potassium hydroxide, urea or ammonia water.
In the present invention, the cation exchange membrane is a conventional cation exchange membrane, preferably a Nafion membrane (Nafion cation exchange membrane) can be selected, and as an example of the present invention, the cation exchange membrane can be selected from DB-Nafion117 (manufactured by DuPont), DB-Nafion115 (manufactured by DuPont), DB-Nafion211 (manufactured by DuPont), DB-Nafion212 (manufactured by DuPont), and the like.
The preparation method of the gas sensing material provided by the invention is characterized in that biomimetic synthesis is carried out by taking a cation exchange membrane as a template, and hydroxyapatite crystals grow on the surface of the cation exchange membrane on one side of a cathode chamber under the condition that the temperature is 40-60 ℃. The crystal growing on the surface of the cation exchange membrane on one side of the anode chamber is in a triangular column shape and has obvious layered growth characteristics. The possible growth mechanism of the sea cucumber-shaped nano crystal cluster is bottom growth which gradually grows in a flower shapeEvolved and come; with the prolonging of crystallization time, the crystallinity of the crystal is improved, the unit cell parameters are gradually reduced, and the grain size is gradually increased. The mass transfer process is accelerated by adding an electric field, but Ca and F have larger electronegativity difference, so that Ca can be caused2+The fluorine-containing compound is enriched on the cation exchange membrane to generate a dense layer of the fluorine-containing compound, thereby preventing the nucleation and growth of ions on the original special structure of the cation exchange membrane. When the voltage is below 3V, the crystals on the membrane are nanoparticles with irregular shapes, the particle size is in the range of 80-90 nm, and the crystals are distributed less uniformly, which indicates that when the voltage is below 3V, enough reactant ions are not driven to permeate the membrane to form a product with ions in a solution on the other side in a short time. When the voltage is increased to be more than 9V, most of the crystal clusters are changed into spiky balls and are formed by the agglomeration of the nano needles.
Furthermore, the anode chamber and the cathode chamber are made of polytetrafluoroethylene and polypropylene, the anode chamber and the cathode chamber are arranged in parallel and oppositely, and the electrode is a platinum electrode.
Further, standing for 7-14 days, washing the cation exchange membrane with water and/or ethanol after standing, drying in vacuum, and collecting an electrolytic deposition product on one side of the cathode chamber on the cation exchange membrane, namely the gas sensing material.
In order to achieve the above object, the present invention further provides a gas sensing material prepared by the method for preparing a gas sensing material, wherein the gas sensing material comprises: the micro-morphology is tubular, the diameter is 5-30 μm, the length is 10-100 μm, the gas sensing material is composed of Rb, Ca, P, H and O, wherein the mole fractions of the O, P, Ca and Rb are 75% -76%, 10% -12% and 0.9% -1.5% respectively,
furthermore, the micro-morphology of the gas sensing material is in a tubular shape with the diameter of 20-30 mu m and the length of 80-100 mu m.
In order to achieve the above object, the present invention further provides a gas sensor, which includes a substrate with an electrode, wherein a surface of the substrate with an electrode is coated with the gas sensing material, and preferably, the substrate with an electrode is an alumina ceramic tube or an alumina ceramic sheet.
Furthermore, the electrodes are two gold electrodes, the gold electrodes are obtained by an electron beam deposition method, the thickness of the gold electrodes is 400-800 nm, the distance between a positive electrode and a negative electrode is 1-2 mm, and two platinum wire electrode leads are respectively led out from the two gold electrodes in the deposition process.
Further, the gas sensing material is placed in an agate mortar, a binder is added, the mixture is fully ground into slurry, the obtained slurry is uniformly coated on the substrate with the electrodes, and the substrate is automatically dried in the shade. Preferably, the binder is ethanol or ultrapure water.
Compared with the prior art, the invention has the advantages that:
the gas sensing material fully utilizes the advantages of hydroxyapatite that the specific surface area is large, the number of gas adsorption sites formed by mesoporous structures and the like is large, the hydroxyapatite has good electric conduction mechanism and the like, and the electric conductivity is further enhanced through electrons provided by rubidium atoms. Therefore, the gas sensing material provided by the invention can be suitable for detecting various toxic and harmful gases at room temperature, and has good sensitivity and stability. Specifically, the following advantages are provided: the gas sensing material can be used for effectively detecting toxic and harmful gases at room temperature. For example, the gas sensor of the invention has the response sensitivity of more than 95% for the toxic and harmful gas with the concentration of 1000ppm, and can detect the toxic and harmful gas with the lowest concentration of 50ppm or even lower; response recovery times are as short as several minutes or even tens of seconds. The preparation process of the gas sensing material adopts a template-assisted method, does not add any harmful substance, is environment-friendly, only needs short-time electrodeposition and constant-temperature standing, and has simple operation method, adjustable raw material proportion and low energy consumption.
Drawings
FIG. 1 is a scanning electron micrograph of a gas sensor material prepared according to the method described in example 4.
FIG. 2 is a transmission electron micrograph of the gas sensor material prepared by the method described in example 4.
FIG. 3 is an energy spectrum of a gas sensor material prepared by the method described in example 4.
Fig. 4 is an X-ray diffraction analysis spectrum of the gas sensing material prepared by the method described in example 4.
FIG. 5 shows NH concentrations of 50ppm to 1000ppm at room temperature, using the gas sensors of examples 1, 2, 3 and 4 and the gas sensor made of pure hydroxyapatite3The response sensitivity of gas detection is compared with the concentration.
FIG. 6 shows NH pairs at room temperature using the gas sensor of example 43Continuous response-recovery curves for different gases at gas concentrations of 50ppm to 1000 ppm.
FIG. 7 shows NH pairs at room temperature using the gas sensor of example 43The gas response-recovery time comparison chart of the gas concentration detection is 200ppm to 1000 ppm.
FIG. 8 shows NH pairs at room temperature for gas sensors using example 438 cycles response-recovery curve with gas concentration of 200 ppm.
FIG. 9 is a graph of the sensitivity of the gas sensing material prepared for example 4 of the present invention to different gas responses at 200ppm concentrations versus time at room temperature.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specified, the reagents and materials used in the present invention are commercially available products or products obtained by a known method.
Example 1
The preparation method of the gas sensing material comprises the following steps:
placing two cylindrical polypropylene bottles with the capacity of 120mL in parallel in a way of facing to each other, fixing a cation exchange membrane with the size close to that of the bottle opening in the middle, respectively forming a rectangular liquid injection opening on the side surface of each of the two polypropylene bottles, respectively inserting a platinum sheet electrode (the electrode size is 1cm x 0.3mm) into each of the two polypropylene bottles, and respectively using the two polypropylene bottles as an anode chamber and a cathode chamber; according to the mole percentage of Rb/(Rb + Ca) of 2.5 percent, the Ca (NO) with the concentration of 0.4875mol/L3)2Adding RbNO with concentration of 0.0125mol/L into the solution by stirring3Obtaining five groups of calcium-rubidium source mixed liquor, and adding the calcium-rubidium source mixed liquor into the anode chamber from a rectangular liquid injection port of the anode chamber; adding 0.3mol/L NH into concentrated ammonia water4H2PO4Adjusting the pH value of the solution to 11 to obtain a phosphorus source solution, and adding the phosphorus source solution into the cathode chamber from a rectangular liquid injection port of the cathode chamber; carrying out electro-deposition for 1h at 50 ℃, then removing electrodes, placing the electrolytic cell in a thermostat at 50 ℃ for standing, and supplementing a calcium-rubidium source mixed solution and a phosphorus source solution in the standing process; and standing for 7 days, taking down the cation exchange membrane, washing with water for 3 times and ethanol for 2 times, drying in vacuum at 60 ℃ for 24 hours, and collecting an electrolytic deposition product on one side of the cathode chamber on the cation exchange membrane to obtain the gas sensing material.
10mg of the gas sensing material obtained in the embodiment was placed in an agate mortar, ethanol was added to the mortar, and the mixture was sufficiently ground and coated on Al with two gold electrodes having a thickness of 1.5mm between the positive and negative electrodes2O3And (3) drying the ceramic wafer substrate in the shade, and mounting the substrate to obtain the gas sensor of the embodiment.
Example 2
The preparation method of the gas sensing material comprises the following steps:
two cylindrical polypropylene bottles with the capacity of 120mL are placed in parallel in a butt joint mode, a cation exchange membrane close to the bottle opening is fixed in the middle, and rectangular liquid injection openings are formed in the side faces of the two polypropylene bottles respectivelyA platinum sheet electrode (electrode size: 1cm x 0.3mm) is respectively inserted into the two polypropylene bottles, and the two polypropylene bottles are respectively used as an anode chamber and a cathode chamber; the molar percentage of Rb/(Rb + Ca) is 5 percent, and the concentration of Ca (NO) is 0.275mol/L3)2The solution and 0.2mol/L calcium acetate solution are stirred and added with RbNO with the concentration of 0.025mol/L3Obtaining five groups of calcium-rubidium source mixed liquor, and adding the calcium-rubidium source mixed liquor into the anode chamber from a rectangular liquid injection port of the anode chamber; adding 0.3mol/L NH into concentrated ammonia water4H2PO4Adjusting the pH value of the solution to 11 to obtain a phosphorus source solution, and adding the phosphorus source solution into the cathode chamber from a rectangular liquid injection port of the cathode chamber; carrying out electro-deposition for 1h at 50 ℃, then removing electrodes, placing the electrolytic cell in a thermostat at 50 ℃ for standing, and supplementing a calcium-rubidium source mixed solution and a phosphorus source solution in the standing process; and standing for 7 days, taking down the cation exchange membrane, washing with water for 5 times respectively, drying in vacuum at 60 ℃ for 24 hours, and collecting an electrolytic deposition product on one side of the cathode chamber on the cation exchange membrane to obtain the gas sensing material.
10mg of the gas sensing material obtained in the example was placed in an agate mortar, ethanol was added to the mortar, the mixture was sufficiently ground, and the ground mixture was coated on Al with two gold electrodes having a thickness of 600nm and a positive and negative electrode gap of 1.5mm2O3And (3) drying the ceramic wafer substrate in the shade, and mounting the substrate to obtain the gas sensor of the embodiment.
Example 3
The preparation method of the gas sensing material comprises the following steps:
placing two cylindrical polypropylene bottles with the capacity of 120mL in parallel in a way of facing to each other, fixing a cation exchange membrane with the size close to that of the bottle opening in the middle, respectively forming a rectangular liquid injection opening on the side surface of each of the two polypropylene bottles, respectively inserting a platinum sheet electrode (the electrode size is 1cm x 0.3mm) into each of the two polypropylene bottles, and respectively using the two polypropylene bottles as an anode chamber and a cathode chamber; at an Rb/(Rb + Ca) mole percent of 20% to a Ca (NO) concentration of 0.475mol/L3)2RbNO with the concentration of 0.025mol/L is added into the solution by stirring3Obtaining five groups of calcium rubidium source mixed liquor from the solution, and obtaining a rectangle of the anode chamberAdding a calcium rubidium source mixed solution into the anode chamber through a liquid injection port; adding 0.3mol/L NH into concentrated ammonia water4H2PO4Adjusting the pH value of the solution to 11 to obtain a phosphorus source solution, and adding the phosphorus source solution into the cathode chamber from a rectangular liquid injection port of the cathode chamber; carrying out electro-deposition for 1h at 50 ℃, then removing electrodes, placing the electrolytic cell in a thermostat at 50 ℃ for standing, and supplementing a calcium-rubidium source mixed solution and a phosphorus source solution in the standing process; and standing for 7 days, taking down the cation exchange membrane, washing with water for 5 times respectively, drying in vacuum at 60 ℃ for 24 hours, and collecting an electrolytic deposition product on one side of the cathode chamber on the cation exchange membrane to obtain the gas sensing material.
10mg of the gas sensing material obtained in the example was placed in an agate mortar, ethanol was added to the mortar, the mixture was sufficiently ground, and the ground mixture was coated on Al with two gold electrodes having a thickness of 600nm and a positive and negative electrode gap of 1.5mm2O3And (3) drying the ceramic wafer substrate in the shade, and mounting the substrate to obtain the gas sensor of the embodiment.
Example 4
The preparation method of the gas sensing material comprises the following steps:
placing two cylindrical polypropylene bottles with the capacity of 120mL in parallel in a way of facing to each other, fixing a cation exchange membrane with the size close to that of the bottle opening in the middle, respectively forming a rectangular liquid injection opening on the side surface of each of the two polypropylene bottles, respectively inserting a platinum sheet electrode (the electrode size is 1cm x 0.3mm) into each of the two polypropylene bottles, and respectively using the two polypropylene bottles as an anode chamber and a cathode chamber; the molar percentage of Rb/(Rb + Ca) is 10 percent, and the concentration of Ca (NO) is 0.45mol/L3)2Stirring and adding an RbCl solution with the concentration of 0.05mol/L into the solution to obtain five groups of calcium-rubidium source mixed liquor, and adding the calcium-rubidium source mixed liquor into the anode chamber from a rectangular liquid injection port of the anode chamber; adding 0.3mol/L NH into concentrated ammonia water4H2PO4Adjusting the pH value of the solution to 11 to obtain a phosphorus source solution, and adding the phosphorus source solution into the cathode chamber from a rectangular liquid injection port of the cathode chamber; carrying out electro-deposition for 1h at 50 ℃, then removing electrodes, placing the electrolytic cell in a thermostat at 50 ℃ for standing, and supplementing a calcium-rubidium source mixed solution and a phosphorus source solution in the standing process; standing for 7 days, and mixingAnd taking down the ion exchange membrane, washing with ethanol for 5 times respectively, drying in vacuum for 24 hours at the temperature of 60 ℃, and collecting an electrolytic deposition product on one side of the cathode chamber on the cation exchange membrane to obtain the gas sensing material.
The scanning electron microscope image of the gas sensing material obtained by the method of the embodiment is shown in fig. 1, the transmission electron microscope image is shown in fig. 2, and the gas sensing material obtained by the method of the embodiment comprises hydroxyapatite which has a tubular microstructure, a diameter of 20-30 μm and a length of 80-100 μm, as shown in fig. 1 and 2.
The energy spectrum of the gas sensing material obtained by the method of the embodiment is shown in fig. 3, and it can be seen from fig. 3 that the gas sensing material is composed of five elements of Rb, Ca, P, H and O, the mole fractions of O, P, Ca and Rb are 75.90%, 11.23%, 11.87% and 1.00%, respectively, and the actual atomic doping ratio of rubidium is only 7.77% and is lower than the theoretical value by 10% through calculation.
An X-ray diffraction analysis spectrogram of the gas sensing material obtained by the method of the embodiment is shown in fig. 4, which shows that CaPO is generated while hydroxyapatite is generated3(OH)、CaHPO4(H2O)、RbH2PO4。
10mg of the gas sensing material obtained in the example was placed in an agate mortar, and after adding high purity water and sufficiently grinding, the material was coated on Al with two gold electrodes having a thickness of 600nm and a positive and negative electrode gap of 1.5mm2O3And (3) automatically drying in the shade on the ceramic sheet substrate, and mounting the substrate to obtain the gas sensor.
FIG. 5 shows NH concentration of 50ppm to 1000ppm at room temperature using the gas sensors described in examples 1, 2, 3 and 4 and a gas sensor made of a conventional hydroxyapatite3Comparison of response sensitivity of gases. As is clear from fig. 5, the response sensitivity of the gas sensor of the present invention is significantly higher than that of the gas sensor made of the conventional hydroxyapatite. The response sensitivity of the gas sensor in the embodiment 1 can reach more than 65% under 1000 ppm; gas sensor of example 2 responds at 1000ppmThe sensitivity can reach more than 75 percent; the gas sensor of example 3 has a response sensitivity of 95% or more at 1000 ppm.
FIG. 6 shows NH pairs at room temperature using the gas sensor described in example 43Continuous response-recovery curve for gas concentration of 50ppm to 1000 ppm. As is clear from FIG. 6, the gas sensor of example 4 can detect NH at room temperature3Responding; the sensitivity of response has obvious positive correlation with the gas concentration; the detectable limit of the gas sensor of example 4 for ammonia gas can be up to 50ppm or less.
FIG. 7 is a graph of NH measurements taken at room temperature using the gas sensor described in example 43Comparing response-recovery time of different gases with gas concentration interval of 200 ppm-1000 ppm. As is clear from fig. 7, the gas sensor of example 4 has a response time as short as several minutes or even several tens of seconds, and the recovery time increases at a faster rate as the gas concentration increases.
FIG. 8 is a graph of NH measurements taken at room temperature using the gas sensor described in example 438 cycles of response-recovery curve for a gas concentration of 200 ppm. As is clear from fig. 8, the gas sensor of example 4 has good reusability and maintains high and stable sensitivity.
FIG. 9 is a response-recovery curve of a harmful gas such as ammonia, n-hexane, and n-heptane having a gas concentration of 200ppm at room temperature using the gas sensor described in example 4. As is clear from fig. 9, the gas sensor prepared in example 4 has good response characteristics to various toxic gases such as ammonia gas, n-hexane, and n-heptane, and has good detection capability to toxic gases.
Claims (5)
1. A preparation method of a gas sensing material is characterized by comprising the following steps: (1) uniformly dispersing 0.0125-0.25 mol/L rubidium salt solution into 0.3-1.0 mol/L calcium ion solution under the stirring condition to obtain calcium-rubidium source mixed solution, injecting the calcium-rubidium source mixed solution with the mole percentage of Rb/(Rb + Ca) of 5-10% into an anode chamber of an electrolytic cell, injecting phosphorus source solution into a cathode chamber of the electrolytic cell according to the mole ratio of (Rb + Ca)/P of 5/3, separating the anode chamber from the cathode chamber by a cation exchange membrane, and performing electrolytic deposition for 1-3 h under the conditions that the voltage is 3-9V and the temperature is 40-60 ℃; the calcium ion solution is selected from one or more of a calcium nitrate solution, a calcium acetate solution or a calcium chloride solution; the rubidium salt solution is selected from one or more of rubidium nitrate solution, rubidium chloride solution or rubidium carbonate solution; the phosphorus source solution is prepared by the following method: adding a pH regulator into a phosphate solution with the concentration of 0.255-0.75 mol/L, and regulating the pH value of the solution to 10-12 to obtain the phosphorus source solution;
(2) removing an electrode, standing the electrolytic cell for 7-14 days at a constant temperature of 25-50 ℃, supplementing a calcium-rubidium source mixed solution and a phosphorus source solution in the standing process, washing a cation exchange membrane by using water and/or ethanol after standing, and collecting an electrolytic deposition product on one side of a cathode chamber on the cation exchange membrane after vacuum drying to obtain the gas sensing material;
the gas sensing material comprises tubular hydroxyapatite with the microscopic morphology of 20-30 mu m in diameter and 80-100 mu m in length; the gas sensing material is composed of Rb, Ca, P, H and O, wherein the mole fractions of the O, P, Ca and Rb are respectively 75-76%, 10-12% and 0.9-1.5%.
2. The method of claim 1, wherein the cation exchange membrane is a Nafion cation exchange membrane.
3. A gas sensor material produced by the method for producing a gas sensor material according to claim 1 or 2.
4. A gas sensor comprising a substrate with an electrode, wherein the surface of the substrate with the electrode is coated with the gas sensing material according to claim 3.
5. The gas sensor according to claim 4, wherein the gas sensing material is placed in an agate mortar, a binder is added thereto, the mixture is sufficiently ground into a slurry, and the resulting slurry is uniformly applied to the surface of the electrode-provided substrate.
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