Gas-sensitive material for ammonia gas detection, preparation method thereof, gas-sensitive electrode and sensor
阅读说明：本技术 氨气检测用气敏材料及其制备方法、气敏电极和传感器 (Gas-sensitive material for ammonia gas detection, preparation method thereof, gas-sensitive electrode and sensor ) 是由 王耀 梁红萍 周国富 于 2020-12-30 设计创作，主要内容包括：本发明公开了一种氨气检测用气敏材料及其制备方法、气敏电极和传感器,该氨气检测用气敏材料包括功能化石墨烯微球和包覆于功能化石墨烯微球上的聚苯胺,功能化石墨烯微球为聚苯乙烯磺酸钠修饰的还原石墨烯微球。本发明氨气检测用气敏材料能在室温条件下对低浓度氨气发生快速响应和回复,反应灵敏度高,检测限低。(The invention discloses a gas-sensitive material for ammonia gas detection, a preparation method thereof, a gas-sensitive electrode and a sensor. The gas sensitive material for ammonia detection can rapidly respond and recover low-concentration ammonia at room temperature, and has high reaction sensitivity and low detection limit.)
1. The gas-sensitive material for ammonia gas detection is characterized by comprising functionalized graphene microspheres and polyaniline coated on the functionalized graphene microspheres, wherein the functionalized graphene microspheres are reduced graphene microspheres modified by sodium polystyrene sulfonate.
2. The gas-sensitive material for ammonia gas detection according to claim 1, wherein the polyaniline is formed by adsorbing aniline monomer onto the functionalized graphene microspheres and performing in-situ chemical oxidative polymerization on the functionalized graphene microspheres.
3. The gas-sensitive material for ammonia gas detection according to claim 1 or 2, wherein the size of the gas-sensitive material for ammonia gas detection is 1 to 4 μm.
4. A method for producing a gas-sensitive material for ammonia gas detection according to any one of claims 1 to 3, characterized by comprising the steps of:
s1, mixing sodium polystyrene sulfonate, graphene oxide and a solvent to prepare a mixed solution, adding a reducing agent, carrying out a heating reaction, and carrying out freeze drying to obtain sodium polystyrene sulfonate modified reduced graphene microspheres;
s2, dispersing the sodium polystyrene sulfonate modified reduced graphene microspheres in acid liquor, and then adding aniline monomers and an initiator to perform in-situ chemical oxidation polymerization reaction.
5. The method for preparing the gas-sensitive material for ammonia gas detection according to claim 4, wherein in step S1, the mass ratio of the sodium polystyrene sulfonate, the reducing agent and the graphene oxide is (1-100): (1-10): 1; preferably, the reducing agent is selected from at least one of hydrazine hydrate, ascorbic acid, sodium borohydride, sodium citrate, sodium hydroxide, hydroiodic acid, cysteine, glycine, glucose, hydroquinone, phenylenediamine, methanol, ethanol, isopropanol, benzyl alcohol, iron, aluminum, and zinc.
6. The preparation method of the gas-sensitive material for ammonia gas detection according to claim 4, wherein in step S2, the mass ratio of the aniline monomer to the sodium polystyrene sulfonate-modified reduced graphene microspheres is (0.1-9): 1.
7. the method for preparing a gas-sensitive material for ammonia gas detection according to claim 4, wherein in step S2, the acid solution is at least one selected from hydrochloric acid, sulfuric acid, phytic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid and polystyrenesulfonic acid.
8. The method for preparing a gas-sensitive material for ammonia gas detection according to claim 4, wherein in step S1, after the heating reaction and before the freeze-drying, impurity removal treatment is further included; and/or in step S2, after the in-situ chemical oxidative polymerization reaction, impurity removal treatment is further included.
9. A gas-sensitive electrode, which is characterized in that a gas-sensitive coating is arranged on the gas-sensitive electrode, and the material of the gas-sensitive coating comprises the gas-sensitive material for ammonia gas detection as defined in any one of claims 1 to 3.
10. A sensor comprising the gas sensing electrode of claim 9.
Technical Field
The invention relates to the technical field of gas-sensitive materials, in particular to a gas-sensitive material for ammonia gas detection, a preparation method thereof, a gas-sensitive electrode and a sensor.
Background
With the development of intelligent manufacturing, people pay more and more attention to health monitoring of the people. Human breath contains high humidity and a large amount of gaseous compounds at concentrations between several ppt and several thousands ppm, is very complex in composition, and depends on health conditions, age, sex, and the like. Ammonia gas (NH)3) Is a protein respiratory product that is generally converted to urea by the liver and excreted through the kidneys. When NH is present3When the concentration of (A) rises from several hundred ppb to a certain ppm, failure of liver/kidney occurs. Research shows that human exhales NH3Is considered healthy, is superior toAn excess of 1.6ppm is considered unhealthy. The realization of the stable monitoring of low-concentration ammonia gas in human breath is very important for the detection of liver/kidney diseases. Thus, p-NH was prepared3Gas sensing devices with high gas sensitivity, good selectivity and good repeatability have become a hotspot for research of scientists.
The resistive semiconductor sensor has been widely studied due to its simple fabrication, convenient operation, and small size, but it has significant challenges in terms of detection limit, stability, fabrication process, and power consumption. Graphene has a large specific surface area and excellent conductivity, is an excellent gas sensitive material, and in recent years, graphene-based materials based on various morphological structures are receiving wide attention in gas sensitive detection. However, unmodified graphene has poor responsiveness and selectivity to gas, and the inherent electrical properties of graphene are damaged by traditional covalent bond modification, so that the important content in the field of ammonia sensors is to find out how to realize high-sensitivity stable trace detection on ammonia at room temperature.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a gas-sensitive material for ammonia gas detection, a preparation method thereof, a gas-sensitive electrode and a sensor.
The invention provides a gas-sensitive material for ammonia gas detection, which comprises functionalized graphene microspheres and polyaniline coated on the functionalized graphene microspheres, wherein the functionalized graphene microspheres are reduced graphene microspheres modified by sodium polystyrene sulfonate (PSS).
The gas-sensitive material for detecting ammonia gas provided by the embodiment of the invention has at least the following beneficial effects: the gas sensitive material for ammonia detection can rapidly respond and recover low-concentration ammonia at room temperature, and has high reaction sensitivity and low detection limit.
According to some embodiments of the present invention, the polyaniline is formed by adsorbing aniline monomer onto the functionalized graphene microspheres and by in-situ chemical oxidative polymerization on the functionalized graphene microspheres. Specifically, the aniline monomer is adsorbed on the functionalized graphene microspheres through a supermolecule effect and is formed on the functionalized graphene microspheres through in-situ chemical oxidation polymerization. Preferably, the supramolecular interactions are pi-pi stacking and electrostatic interactions. By coating polyaniline on the functionalized graphene microspheres in the manner, compared with the traditional polyaniline nanowire and polyaniline film, the obtained material has larger electron transmission capability and more stable transmission.
According to some embodiments of the invention, the size of the gas sensitive material for ammonia gas detection is 1-4 μm.
In a second aspect of the present invention, there is provided a method for preparing any one of the gas-sensitive materials for ammonia gas detection provided by the first aspect of the present invention, comprising the steps of:
s1, mixing sodium polystyrene sulfonate (PSS), graphene oxide and a solvent to prepare a mixed solution, adding a reducing agent, carrying out a heating reaction, and carrying out freeze drying to prepare the sodium polystyrene sulfonate modified reduced graphene microspheres;
s2, dispersing the sodium polystyrene sulfonate modified reduced graphene microspheres in acid liquor, and then adding aniline monomers and an initiator to perform in-situ chemical oxidation polymerization reaction.
The preparation method of the gas-sensitive material for ammonia gas detection provided by the embodiment of the invention at least has the following beneficial effects: the raw materials used in the preparation method are simple, and the cost is low; the polyaniline-coated functionalized graphene microspheres are prepared by taking a reaction monomer (aniline monomer) and a conductive matrix substance (sodium polystyrene sulfonate-modified reduced graphene microspheres) as raw materials, the aniline monomer and the functionalized graphene microspheres are adsorbed together through a supermolecule effect, an initiator is utilized to initiate the aniline monomer to polymerize on the conductive matrix substance, and the material formed by the method has high electron transmission capability and stable transmission; the gas-sensitive material with the hollow microsphere structure, which is uniform in size and stable in structure, can be prepared by the method, the structure has a large specific surface area, the prepared material can quickly respond and recover low-concentration ammonia gas at room temperature, the reaction sensitivity is high, and the detection limit is low.
According to some embodiments of the invention, in step S1, the mass ratio of the sodium polystyrene sulfonate, the reducing agent and the graphene oxide is (1-100): (1-10): 1; preferably, the reducing agent is selected from at least one of hydrazine hydrate, ascorbic acid, sodium borohydride, sodium citrate, sodium hydroxide, hydroiodic acid, cysteine, glycine, glucose, hydroquinone, phenylenediamine, methanol, ethanol, isopropanol, benzyl alcohol, iron, aluminum, and zinc.
In addition, in step S1, graphene oxide may be dispersed in a solvent to prepare a graphene oxide dispersion solution, and then sodium polystyrene sulfonate is added and mixed to prepare a mixed solution; or dispersing graphene oxide in a part of the solvent to prepare graphene oxide dispersion liquid, dissolving sodium polystyrene sulfonate in the rest of the solvent, and mixing with the graphene oxide dispersion liquid to prepare a mixed solution. Wherein, deionized water is generally adopted as the solvent. The reaction temperature of the heating reaction is generally controlled to be 70-90 ℃, and preferably 80 ℃.
According to some embodiments of the invention, in step S2, the mass ratio of the aniline monomer to the sodium polystyrene sulfonate-modified reduced graphene microspheres is (0.1-9): 1. the concentration of the added aniline monomer can be controlled to be (0.01-0.5) mol/L. Further, as the initiator, at least one of persulfate (e.g., ammonium persulfate, potassium persulfate, etc.), hydrogen oxide, dichromate, iron chloride, benzoyl peroxide t-butyl peroxide, methyl ethyl ketone peroxide, azobisisobutyronitrile, azobisisobutylamidine hydrochloride, azobisisoheptonitrile, and dimethyl azobisisobutyrate can be used.
According to some embodiments of the invention, in step S2, the acid solution is at least one selected from hydrochloric acid, sulfuric acid, phytic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, and polystyrenesulfonic acid. The sodium polystyrene sulfonate modified reduced graphene microspheres are dispersed in acid liquor, ultrasonic treatment can be carried out firstly, and the ultrasonic treatment time can be controlled within 30-60 min. In addition, the reaction temperature of the in-situ chemical oxidation polymerization reaction is generally controlled to be-10-90 ℃, and preferably 4 ℃.
According to some embodiments of the invention, in step S1, after the heating reaction and before the freeze-drying, an impurity removal process is further included; and/or in step S2, after the in-situ chemical oxidative polymerization reaction, impurity removal treatment is further included. Specifically, in step S1, after the heating reaction is completed, the product may be filtered to remove excess reducing agent and free PSS, and then redispersed in deionized water to obtain a stable supramolecular assembly dispersion liquid, and then freeze-dried to obtain the sodium polystyrene sulfonate modified reduced graphene microspheres. After the in-situ chemical oxidative polymerization is completed, the product may be centrifuged to remove excess hydrochloric acid, initiator and unreacted aniline monomer, step S2.
In a third aspect of the present invention, a gas-sensitive electrode is provided, where a gas-sensitive coating is provided on the gas-sensitive electrode, and a material of the gas-sensitive coating includes the gas-sensitive material for ammonia gas detection provided in the first aspect of the present invention. Specifically, the gas-sensitive material for ammonia gas detection is dispersed in deionized water to prepare a dispersion liquid, and then the dispersion liquid is coated on the interdigital electrode and dried to prepare the gas-sensitive electrode.
In a fourth aspect of the invention, there is provided a sensor comprising any one of the gas sensing electrodes provided in the fourth aspect of the invention. The sensor can be used for ammonia gas detection.
Drawings
The invention is further described with reference to the following figures and examples, in which:
FIG. 1 is a flow chart of a process for producing a gas-sensitive material for ammonia gas detection according to example 1;
FIG. 2 is an SEM topography of PSS functionalized graphene microspheres prepared in example 1 at different magnifications;
FIG. 3 is an SEM topography of different magnifications of the gas sensitive material for ammonia gas detection in example 1;
FIG. 4 is FTIR plots of gas sensitive materials for ammonia gas detection of example 1, comparative example 2 and comparative example 3;
FIG. 5 is a state diagram of the gas-sensitive material dispersions for ammonia gas detection in example 1 and comparative examples 1 to 3;
FIG. 6 is a gas-sensitive test graph of the gas-sensitive material for ammonia gas detection in example 1 and comparative examples 1 to 3, with respect to 50ppm of ammonia gas;
FIG. 7 shows the results of the test of the response of the gas-sensitive material for ammonia gas detection of example 1 to ammonia gas of different concentrations;
FIG. 8 shows the results of the cycle stability test of the gas sensitive material for detecting ammonia gas at 50ppm in example 1.
Detailed Description
The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.
Example 1
A gas-sensitive material for ammonia gas detection, as shown in fig. 1, the preparation method comprises the following steps:
s1, dissolving 80mg of sodium polystyrene sulfonate (PSS) in 10mL of deionized water, adding the deionized water into a 50mL single-neck flask, and adding 4mL of graphene oxide dispersion liquid (1mg/mL) into the single-neck flask to obtain a mixed solution; adding 10mL of hydrazine hydrate (1.12 mu L/mL) into the mixed solution, and reacting at 80 ℃ for 1h to obtain the PSS functionalized graphene; filtering the product to remove redundant hydrazine hydrate and free PSS, and then re-dispersing the product in 10mL of deionized water to obtain stable supermolecular assembly dispersion liquid; then, freeze-drying the supermolecule assembly dispersion liquid to obtain sodium polystyrene sulfonate modified reduced graphene microspheres, namely PSS functionalized graphene microspheres;
s2, dispersing 10mg of the sodium polystyrene sulfonate modified reduced graphene microspheres prepared in the step S1 into 2.5mL of hydrochloric acid solution (1M), performing ultrasonic treatment for 30min, and adding 2.5mg of Aniline (ANI) monomer to obtain a dispersion liquid containing aniline monomer; and (2) placing the dispersion containing the aniline monomer in a refrigerator at 4 ℃, adding 12.5mg of initiator Ammonium Persulfate (APS) to perform in-situ chemical oxidative polymerization for 4h, and centrifuging the product at 13000r/min for 10min to remove redundant hydrochloric acid, APS and unreacted aniline monomer to obtain the polyaniline-coated graphene microsphere (PANI @ PSS-rGO) for ammonia detection.
Example 2
A gas sensitive material for ammonia detection is prepared by the following steps:
s1, dissolving 100mg of sodium polystyrene sulfonate (PSS) in 10mL of deionized water, adding the deionized water into a 50mL single-neck flask, and adding 4mL of graphene oxide dispersion liquid (1mg/mL) into the single-neck flask to obtain a mixed solution; adding 10mL of hydrazine hydrate (1.12 mu L/mL) into the mixed solution, and reacting at 80 ℃ for 1h to obtain the PSS functionalized graphene; filtering the product to remove redundant hydrazine hydrate and free PSS, and then re-dispersing the product in 10mL of deionized water to obtain stable supermolecular assembly dispersion liquid; then, freeze-drying the supermolecule assembly dispersion liquid to obtain sodium polystyrene sulfonate modified reduced graphene microspheres, namely PSS functionalized graphene microspheres;
s2, dispersing 10mg of the sodium polystyrene sulfonate modified reduced graphene microspheres prepared in the step S1 in 90mL of sulfuric acid solution (1M), performing ultrasonic treatment for 30min, and adding 90mg of Aniline (ANI) monomer to obtain a dispersion liquid containing aniline monomer; and placing the dispersion liquid containing the aniline monomer in a refrigerator at 4 ℃, adding 450mg of initiator Ammonium Persulfate (APS) to perform in-situ chemical oxidative polymerization for 4h, and centrifuging the product at 13000r/min for 10min to remove redundant hydrochloric acid, APS and unreacted aniline monomer to obtain the gas sensitive material for ammonia gas detection.
Example 3
A gas sensitive material for ammonia detection is prepared by the following steps:
s1, dissolving 100mg of sodium polystyrene sulfonate (PSS) in 10mL of deionized water, adding the deionized water into a 50mL single-neck flask, and adding 4mL of graphene oxide dispersion liquid (1mg/mL) into the single-neck flask to obtain a mixed solution; adding 10mL of hydrazine hydrate (1.12 mu L/mL) into the mixed solution, and reacting at 80 ℃ for 1h to obtain the PSS functionalized graphene; filtering the product to remove redundant hydrazine hydrate and free PSS, and then re-dispersing the product in 10mL of deionized water to obtain stable supermolecular assembly dispersion liquid; then, freeze-drying the supermolecule assembly dispersion liquid to obtain sodium polystyrene sulfonate modified reduced graphene microspheres, namely PSS functionalized graphene microspheres;
s2, dispersing 9mg of the sodium polystyrene sulfonate modified reduced graphene microspheres prepared in the step S1 in 1mL of sulfuric acid solution (1M), performing ultrasonic treatment for 30min, and adding 1mg of Aniline (ANI) monomer to obtain a dispersion liquid containing aniline monomer; and (2) placing the dispersion liquid containing the aniline monomer in a refrigerator at 4 ℃, then adding 5mg of initiator Ammonium Persulfate (APS) to perform in-situ chemical oxidative polymerization for 4h, and then centrifuging the product at 13000r/min for 10min to remove redundant hydrochloric acid, APS and unreacted aniline monomer, thereby obtaining the gas sensitive material for ammonia gas detection.
Comparative example 1
A gas sensitive material for ammonia detection is prepared by the following steps:
s1, adding 4mL of graphene oxide dispersion liquid (1mg/mL) and 10mL of hydrazine hydrate (1.12 mu L/mL) into a 50mL single-neck flask, and reacting at 80 ℃ for 1 h; filtering the product to remove redundant hydrazine hydrate, and then re-dispersing the product in 10mL of deionized water to obtain a reduced graphene dispersion liquid with unstable dispersion; and then carrying out freeze drying treatment on the reduced graphene dispersion liquid to obtain the solid reduced graphene.
S2, weighing 10mg of the reduced graphene prepared in the step S1, dispersing the reduced graphene in 2.5mL of hydrochloric acid solution (1M), performing ultrasonic treatment for 30min, and adding 2.5mg of aniline monomer to obtain a dispersion liquid containing aniline monomer; and (2) placing the dispersion containing the aniline monomer in a refrigerator at 4 ℃, adding 12.5mg of initiator Ammonium Persulfate (APS) to perform in-situ chemical oxidative polymerization for 4h, and centrifuging the product at 13000r/min for 10min to remove redundant hydrochloric acid, APS and unreacted aniline monomer to obtain the gas sensitive material for ammonia gas detection, namely the polyaniline/graphene (PANI/rGO) composite material.
Comparative example 2
A gas sensitive material for ammonia detection is prepared by the following steps:
adding 2.5mg of aniline monomer into 2.5mL of hydrochloric acid solution (1M), performing ultrasonic treatment for 30min, placing the hydrochloric acid solution containing aniline monomer into a refrigerator at 4 ℃, adding 12.5mg of initiator Ammonium Persulfate (APS) to perform in-situ chemical oxidation polymerization for 4h, and centrifuging the product at 13000r/min for 10min to remove redundant hydrochloric acid, APS and unreacted aniline monomer to obtain the Polyaniline (PANI) gas sensitive material for ammonia gas detection.
Comparative example 3
A gas sensitive material for ammonia detection is prepared by the following steps:
dissolving 80mg of sodium polystyrene sulfonate (PSS) in 10mL of deionized water, adding the solution into a 50mL single-neck flask, and adding 4mL of graphene oxide dispersion (1mg/mL) into the single-neck flask to obtain a mixed solution; adding 10mL of hydrazine hydrate (1.12. mu.L/mL) into the mixed solution, and reacting at 80 ℃ for 1 h; filtering the product to remove redundant hydrazine hydrate and free PSS, and then re-dispersing the product in 10mL of deionized water to obtain stable supermolecular assembly dispersion liquid; and then, carrying out freeze drying treatment on the supermolecule assembly dispersion liquid to obtain a gas sensitive material for ammonia gas detection, namely the reduced graphene (PSS-rGO) modified by sodium polystyrene sulfonate.
The PSS functionalized graphene microspheres prepared in example 1 (i.e., the gas-sensitive material for ammonia gas detection prepared in comparative example 3) and the gas-sensitive material for ammonia gas detection of the product were observed and detected by using a scanning electron microscope, and the obtained results are shown in fig. 2 and fig. 3, respectively. In addition, the gas-sensitive materials for ammonia gas detection of example 1, comparative example 2 and comparative example 3 were subjected to detection analysis by a fourier infrared spectrometer, and the obtained results are shown in fig. 4. As can be seen from fig. 2 to 3, in example 1, a PPS functionalized graphene microsphere is used as a matrix, and polyaniline is polymerized in situ to obtain a more stable microsphere structure; fig. 4 further shows that polyaniline is successfully grown on the PPS functionalized graphene microspheres.
The gas-sensitive material prepared by the method can be used for preparing a gas-sensitive electrode and further preparing a sensor for ammonia gas detection. Specifically, the gas-sensitive material can be dispersed in deionized water to prepare dispersion liquid, then the dispersion liquid is coated on the interdigital electrode, drying is carried out, a gas-sensitive coating is formed on the interdigital electrode, and the gas-sensitive electrode is prepared and can be connected to a sensor for ammonia gas detection so as to be used for gas-sensitive test.
Specifically, the gas-sensitive materials for ammonia gas detection in example 1 and comparative examples 1 to 3 above can be respectively dispersed in 10mL of deionized water to form a dispersion, and the state diagram of the formed dispersion is shown in fig. 5; then coating 5 mu L of dispersion liquid on the interdigital electrode, and drying at 60 ℃ to obtain a gas-sensitive electrode; and connecting the gas-sensitive electrode to a sensor for ammonia gas detection for gas-sensitive test. The specific detection method comprises the following steps: the gas-sensitive electrode of the sensor for detecting ammonia gas can be placed in a closed test cavity of air atmosphere to test the initial resistance, then ammonia gas with a certain concentration is injected into the test cavity to record the resistance value (real-time resistance), after the response is completed, the test cavity is opened to recover the air atmosphere in the test cavity, and the change of the resistance of the detection electrode is recorded.
By adopting the method, the sensors prepared by the gas-sensitive materials for ammonia gas detection in the example 1 and the comparative examples 1 to 3 are respectively applied, the gas-sensitive response and recovery test is carried out on the ammonia gas with the concentration of 50ppm under the conditions that the relative humidity is 30% and the temperature is 25 +/-1.5 ℃, so as to examine the response and recovery performance of each gas-sensitive material to the ammonia gas, and the obtained result is shown in figure 6. In fig. 6, a is a result of a response and recovery test of the gas sensitive material (PANI @ PSS-rGO) for ammonia gas detection in example 1 to ammonia gas, B is a result of a response and recovery test of the gas sensitive material (PANI/rGO) for ammonia gas detection in comparative example 1 to ammonia gas, C is a result of a response and recovery test of the gas sensitive material (PANI) for ammonia gas detection in comparative example 2 to ammonia gas, and D is a result of a response and recovery test of the gas sensitive material (PSS-rGO) for ammonia gas detection in comparative example 3 to ammonia gas. As can be seen from fig. 6, the gas-sensitive material for ammonia gas detection prepared in example 1 has a relatively high response value to ammonia gas, and the gas-sensitive materials for ammonia gas detection prepared in comparative examples 1 to 3 do not have a high response value to ammonia gas. Specifically, the response of the gas sensitive material (PANI @ PSS-rGO) for detecting ammonia in example 1 to 50ppm of ammonia is up to 640%, and the response time and the recovery time are respectively 9s and 120 s; comparative example 1 the gas sensitive material for ammonia gas detection (PANI/rGO) responded 127% to 50ppm ammonia gas, and the response time and recovery time were 9s and 89s, respectively; comparative example 2 the response of the gas sensitive material (PANI) for ammonia detection to 50ppm ammonia was up to 195%, with response and recovery times of 9s and 323s, respectively; comparative example 3 the gas sensitive material for ammonia gas detection (PSS-rGO) responded 81% to 50ppm of ammonia gas with a response time of 57s, and the response could not be completely recovered.
The sensor using the gas sensitive material for ammonia gas detection in example 1 was used to perform response tests on ammonia gas at different concentrations (0.01ppm, 0.05ppm, 0.15ppm, 0.2ppm, 0.35ppm, 1ppm, 2ppm, 5ppm, 10ppm, 20ppm, 30ppm, 40ppm, 50ppm and 60ppm) at a relative humidity of 30% and a temperature of 25 ± 1.5 ℃ to examine the response performance of the gas sensitive material to ammonia gas at different concentrations, and the results are shown in fig. 7. In fig. 7, (a) is response data of the gas-sensitive material for ammonia gas detection to ammonia gas of different concentrations, and (b) is a relationship between the response data of the gas-sensitive material for ammonia gas detection to ammonia gas and ammonia gas concentration. As can be seen from fig. 7, the response of the gas sensitive material for ammonia gas detection in example 1 to ammonia gas has a good linear relationship within a certain concentration range.
In addition, the sensor using the gas sensor material for ammonia gas detection of example 1 was used to detect ammonia gas at a concentration of 50ppm at a relative humidity of 30% and a temperature of 25 ± 1.5 ℃ according to the above method, and the test was repeated to perform the cycle stability test, and the results are shown in fig. 8. As can be seen from fig. 8, the gas-sensitive material for ammonia gas detection in example 1 has good cycle stability when used for ammonia gas detection.
Therefore, the invention obtains the functionalized graphene microspheres by supermolecule assembly of PSS on graphene by using supermolecule interaction, then uses the functionalized graphene microspheres as a matrix material to adsorb aniline monomers on the functionalized graphene microspheres by using pi-pi conjugation and electrostatic interaction, further polymerized in situ to form polyaniline nano-particles, the obtained gas-sensitive material can keep the inherent electrochemical property of graphene, and can form stable dispersion liquid, polyaniline is polymerized on the surface of the functionalized graphene microsphere in situ, the microsphere structure is more stable, the high specific surface area of the microsphere is kept, the electron transmission capacity is improved, the material keeps excellent gas-sensitive performance, the final material can quickly respond and recover low-concentration ammonia gas under the room temperature condition (25 +/-1.5 ℃), the reaction sensitivity is high, and the detection limit is low.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.