Near-infrared light gain gas sensing film and preparation method and application thereof
阅读说明：本技术 一种近红外光增益气体传感薄膜及其制备方法和应用 (Near-infrared light gain gas sensing film and preparation method and application thereof ) 是由 王耀 梁红萍 周国富 于 2021-07-06 设计创作，主要内容包括：本发明公开了一种近红外光增益气体传感薄膜及其制备方法和应用,该近红外光增益气体传感薄膜包括气敏传感材料层和设于气敏传感材料层的表面的上转换纳米颗粒层；上转换纳米颗粒层的材料为聚电解质修饰的上转换纳米颗粒；气敏传感材料层的材料为具有光催化活性的气敏传感材料,光催化活性的激发光为紫外光、可见光中的至少一种。本发明近红外光增益气体传感薄膜通过以上上转换纳米颗粒层的引入,可将气敏传感材料层的光催化活化气敏的光源扩宽到近红外区,以利用波长较长、穿透能力大且对身体无害的近红外光催化活化气体传感,并且可降低检测限,显著提高敏感度。(The invention discloses a near-infrared light gain gas sensing film and a preparation method and application thereof, wherein the near-infrared light gain gas sensing film comprises a gas-sensitive sensing material layer and an up-conversion nano particle layer arranged on the surface of the gas-sensitive sensing material layer; the material of the upconversion nanoparticle layer is polyelectrolyte-modified upconversion nanoparticles; the material of the gas-sensitive sensing material layer is a gas-sensitive sensing material with photocatalytic activity, and the exciting light with photocatalytic activity is at least one of ultraviolet light and visible light. By introducing the up-conversion nanoparticle layer, the near-infrared light gain gas sensing film can widen the light source of the photo-catalytically activated gas-sensitive material layer to the near-infrared region, so that the near-infrared photo-catalytically activated gas sensing with longer wavelength, high penetrating power and no harm to the body is utilized, the detection limit can be reduced, and the sensitivity is obviously improved.)
1. The near-infrared light gain gas sensing film is characterized by comprising a gas-sensitive sensing material layer and an up-conversion nano particle layer which are arranged in a laminated manner; the material of the up-conversion nanoparticle layer is polyelectrolyte-modified up-conversion nanoparticles; the material of the gas-sensitive sensing material layer is a gas-sensitive sensing material with photocatalytic activity, and the exciting light with photocatalytic activity is at least one of ultraviolet light and visible light.
2. The near-infrared light gain gas sensing film of claim 1, wherein the upconverting nanoparticle has a structure of ABF4: yb, RE, wherein A is Na or K, B is Y orGd, wherein RE is Er, Tm or Ho; preferably, the molar ratio of A, Yb to RE in the upconversion nanoparticles is (0.5-0.8): (0.2-0.6): 0.005-0.05).
3. The near-infrared light gain gas sensing film of claim 1, wherein the polyelectrolyte is selected from at least one of a polyacid electrolyte, a polybase electrolyte, a polyphosphate, a polystyrene sulfonate, and a protein.
4. The near-infrared light gain gas sensing thin film according to any one of claims 1 to 3, wherein a material of the gas-sensitive sensing material layer is selected from at least one of a metal oxide, a carbon material, a transition metal disulfide;
preferably, the metal oxide is at least one selected from zinc oxide, tin oxide, indium oxide, titanium dioxide, tungsten trioxide, nickel oxide, copper oxide, and cuprous oxide; the carbon material is selected from at least one of graphene and derivatives thereof; the transition metal disulfide is at least one selected from molybdenum disulfide and selenium disulfide.
5. The method for preparing a near-infrared light gain gas sensing thin film according to any one of claims 1 to 4, comprising the steps of:
s1, preparing polyelectrolyte-modified upconversion nanoparticles;
s2, spin-coating polyelectrolyte-modified upconversion nanoparticles on a substrate to prepare an upconversion nanoparticle layer; and arranging a gas-sensitive sensing material layer on the up-conversion nano particle layer.
6. The method for preparing a near-infrared light gain gas sensing film according to claim 5, wherein the step S1 specifically comprises:
mixing and heating a rare earth raw material, an alkali metal source, a fluorine source, oleic acid and 1-octadecene to synthesize upconversion nanoparticles containing oleic acid ligands by a thermal decomposition method; the alkali metal source is selected from at least one of a potassium source and a sodium source;
and secondly, performing ligand exchange on the oleic acid ligand of the up-conversion nano-particles by adopting polyelectrolyte to prepare the up-conversion nano-particles modified by the polyelectrolyte.
7. The method for preparing a near-infrared light gain gas sensing thin film according to claim 6, wherein the rare earth raw material is at least one selected from rare earth acetate, rare earth chloride, rare earth nitrate, rare earth carbonate, and rare earth trifluoroacetate; preferably, the rare earth element in the rare earth raw material comprises any one of erbium, thulium and holmium in combination with yttrium and ytterbium.
8. The method for preparing a near-infrared light gain gas sensing film according to claim 6, wherein the step (r) specifically comprises: mixing a rare earth raw material with oleic acid and 1-octadecene, and then stirring for reaction at 120-160 ℃; cooling to 60-80 ℃, adding a methanol mixed solution of an alkali metal source and a fluorine source, reacting at 30-50 ℃, and removing methanol after the reaction is finished; heating to 250-350 ℃ under vacuum condition and under the protection of inert gas for reaction to prepare up-conversion nanoparticles containing oleic acid ligands;
the second step specifically comprises: dispersing the upconversion nanoparticles containing oleic acid ligands in acid liquor, removing the oleic acid ligands, then dispersing in water again, and adding polyelectrolyte for reaction to prepare the polyelectrolyte-modified upconversion nanoparticles.
9. A gas-sensitive electrode comprising a base electrode and the near-infrared light gain gas sensor film according to any one of claims 1 to 4, wherein the near-infrared light gain gas sensor film is provided on a surface of the base electrode.
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 near-infrared light gain gas sensing film, a preparation method and application thereof, and specifically relates to a near-infrared light gain gas sensing film, a preparation method thereof, a gas-sensitive electrode and a sensor.
Background
Gas sensors are widely used in environmental monitoring, aerospace, and diagnosis of diseases exhaled by human bodies. Most of gas sensors in the current market detect metal oxides at high temperature (100-400 ℃), and have the defects of instability, high energy consumption, short service life, insecurity in certain application occasions and the like. Photocatalytic activated gas sensing is an effective method for achieving detection of target gases at room temperature. The principle of photocatalytic activation is that under the excitation of light with specific wavelength, a sensing material absorbs the light to generate a photo-generated carrier, wherein photo-generated electrons can react with oxygen pre-adsorbed on the surface of the sensing material to generate active oxygen species, and when the sensing material is in a target gas environment, target molecules act on the active oxygen species on the surface of the sensing material and generate electron transfer. The electric signals are output to an external circuit to obtain corresponding gas sensing signals.
At present, due to the limitation of wide band gap of the sensing material, the sensing excitation wavelength of the commonly used photocatalytic activation gas is basically in the ultraviolet light and visible light regions. The ultraviolet light energy consumption is large, and the ultraviolet light energy is harmful to human bodies, so that researchers can realize photocatalytic activated gas sensing under visible light by means of heteroatom doping, photosensitizers, special nanostructure construction and the like, but the visible light energy is weak, and the improvement of the comprehensive gas-sensitive performance of the sensing material is limited.
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 near-infrared light gain gas sensing film, and a preparation method and application thereof.
The invention provides a near-infrared light gain gas sensing film, which comprises a gas-sensitive sensing material layer and an up-conversion nano particle layer which are arranged in a laminated manner; the material of the up-conversion nanoparticle layer is polyelectrolyte-modified up-conversion nanoparticles; the material of the gas-sensitive sensing material layer is a gas-sensitive sensing material with photocatalytic activity, and the exciting light with photocatalytic activity is at least one of ultraviolet light and visible light.
The near-infrared light gain gas sensing film provided by the embodiment of the invention has at least the following beneficial effects: this near-infrared light gain gas sensing film is through setting up the up-conversion nano particle layer on the basis of gas sensing material layer, it can launch high-energy ultraviolet light or visible light under the excitation of low-energy near-infrared light, and the absorption spectrum of gas sensing material layer can overlap well with the emission spectrum of up-conversion nano particle layer, two-layer body laminating sets up, energy transfer can take place between the two, make the ultraviolet light or the visible light accessible radiant energy transfer and/or the non-radiant energy transfer that the up-conversion nano particle layer produced under near-infrared light shines be absorbed by gas sensing material layer, gas sensing material can produce active oxygen species with the oxygen effect of adsorbing on the material surface in advance after energy excitation, thereby realize the gas-sensitive reinforcing under the excitation of near-infrared light. By introducing the up-conversion nanoparticle layer, the light source of the photocatalytic activated gas-sensitive material layer can be widened to the near infrared region, so that the near infrared photocatalytic activated gas sensing with longer wavelength, high penetration capacity and no harm to the body is utilized, the detection limit can be reduced, and the sensitivity can be improved.
The gas-sensitive sensing material layer and the up-conversion nanoparticle layer in the near-infrared light gain gas sensing film can be combined together through spin-coating electrostatic self-assembly in the preparation process.
Upconversion nanoparticles (UCNPs) are luminescent materials that emit high-energy visible light, even ultraviolet light, under excitation of low-energy near-infrared light, and in some embodiments of the invention, the upconversion nanoparticles are of the formula ABF4: yb and RE, wherein A is Na or K, B is Y or Gd, and RE is Er, Tm or Ho; preferably, the molar ratio of A, Yb to RE in the upconversion nanoparticles is (0.5-0.8): (0.2-06): 0.005-0.05). Specifically, the upconversion nanoparticles may be selected from NaYF4: yb, Er and NaYF4：Yb，Tm、NaYF4：Yb，HO、NaGdF4：Yb，Er、NaGdF4：Yb，Tm、NaGdF4：Yb，Ho、KGdF4：Yb，Er、KGdF4：Yb，Tm、KGdF4：Yb，Ho、KYF4：Yb，Ho、KYF4: yb, Er and KYF4: yb, Tm. In addition, upconversion nanoparticles having a particle size within 100nm are generally used, preferably, the particle size of the upconversion nanoparticles is 10nm to 80 nm.
The polyelectrolyte has good water solubility and charges, so that effective layer-by-layer assembly can be realized, and in addition, the polyelectrolyte has acid and alkali resistance, so that the upconversion nanoparticles can be protected to ensure the luminous efficiency of the upconversion nanoparticles, and therefore, the upconversion nanoparticles are coated and modified by the polyelectrolyte. In some embodiments of the present invention, the polyelectrolyte is selected from at least one of polyacids electrolytes (e.g., polystyrene sulfonic acid, polyvinyl phosphoric acid, polymethacrylic acid, polyacrylic acid, etc.), polybases electrolytes (e.g., polyethyleneimine, polyvinylamine, polyvinylpyridine, etc.), polyphosphates, polystyrene sulfonates (e.g., sodium polystyrene sulfonate), proteins.
In some embodiments of the present invention, the material of the gas-sensitive sensing material layer is selected from at least one of metal oxides, carbon materials, transition metal disulfides;
preferably, the metal oxide is selected from zinc oxide (ZnO), tin oxide (SnO)2) Indium oxide (In)2O3) Titanium dioxide (TiO)2) Tungsten trioxide (WO)3) Nickel oxide (NiO), copper oxide (CuO), cuprous oxide (Cu)2At least one of O); the carbon material is selected from at least one of graphene and derivatives thereof; the transition metal disulfide is at least one selected from molybdenum disulfide and selenium disulfide.
In a second aspect of the present invention, a method for preparing any one of the near-infrared light gain gas sensing thin films provided in the first aspect of the present invention is provided, including the following steps:
s1, preparing polyelectrolyte-modified upconversion nanoparticles;
s2, spin-coating polyelectrolyte-modified upconversion nanoparticles on a substrate to prepare an upconversion nanoparticle layer; and arranging a gas-sensitive sensing material layer on the up-conversion nano particle layer.
In some embodiments of the present invention, step S1 specifically includes:
mixing and heating a rare earth raw material, an alkali metal source, a fluorine source, Oleic Acid (OA) and 1-octadecene to synthesize upconversion nanoparticles containing Oleic acid ligands by a thermal decomposition method; the alkali metal source is selected from at least one of a potassium source and a sodium source; specifically, NaOH, NaCl, KOH, KCl, etc. can be used;
and secondly, performing ligand exchange on the oleic acid ligand of the up-conversion nano-particles by adopting polyelectrolyte to prepare the up-conversion nano-particles modified by the polyelectrolyte.
The upconversion nanoparticles are modified by polyelectrolyte so as to coat a layer of polyelectrolyte on the outer surface of the upconversion nanoparticles, and on one hand, a shell layer can be constructed to protect the particles from being influenced by-OH and-NH2And COO-and the like to improve the up-conversion luminous efficiency; on the other hand, a surface functional group can be introduced to convert the surface functional group from oil solubility to water solubility, and further combined with the gas-sensitive sensing material.
In some embodiments of the invention, the rare earth source material is selected from at least one of rare earth acetate, rare earth chloride, rare earth nitrate, rare earth carbonate, rare earth trifluoroacetate; preferably, the rare earth element in the rare earth raw material comprises any one of erbium, thulium and holmium in combination with yttrium and ytterbium.
For example, rare earth raw materials can be rare earth acetates, such as erbium acetate (Er (C)2H3O2)3·6H2O), thulium acetate (Tm (C)2H3O2)3·6H2O), holmium acetate (Ho (C)2H3O2)3·6H2O) and yttrium acetate (Y (C)2H3O2)3·6H2O), ytterbium acetate (Yb (C)2H3O2)3·6H2O) combinations; or rare earth chlorides, e.g. erbium chloride (ErCl)3·6H2O), thulium chloride (TmCl)3·6H2O), holmium chloride (HoCl)3·6H2O) with yttrium chloride (YCl)3·6H2O), ytterbium chloride (YbCl)3·6H2O) combinations; or rare earth nitrates, e.g. erbium nitrate (Er (NO)3)3) Thulium nitrate (Tm (NO)3)3) Holmium nitrate (Ho (NO)3)3) Any of the above with yttrium nitrate (Y (NO)3)3) Ytterbium nitrate (Yb (NO)3)3) A combination of (1); or rare earth carbonates, e.g. erbium (Er) carbonate2(CO3)3) Thulium carbonate (Tm)2(CO3)3) Holmium carbonate (Ho)2(CO3)3) Any one of with yttrium carbonate (Y)2(CO3)3) Ytterbium carbonate (Yb)2(CO3)3) A combination of (1); or a rare earth trifluoroacetate salt, e.g. erbium trifluoroacetate (Er (CF)3COO)3) Thulium trifluoroacetate (Tm (CF)3COO)3) Holmium trifluoroacetate (Ho (CF)3COO)3) Any of (a) and yttrium trifluoroacetate (Y (CF)3COO)3) Ytterbium trifluoroacetate (Yb (CF)3COO)3) Combinations of (a) and (b). Of course, the rare earth raw material can also adopt the combination of at least two of rare earth acetate, rare earth chloride, rare earth nitrate, rare earth carbonate and rare earth trifluoroacetate.
In some embodiments of the present invention, step (i) specifically includes: mixing a rare earth raw material with oleic acid and 1-octadecene, and then stirring for reaction at 120-160 ℃; cooling to 60-80 ℃, adding a methanol mixed solution of an alkali metal source and a fluorine source, reacting at 30-50 ℃, and removing methanol after the reaction is finished; heating to 250-350 ℃ under vacuum condition and under the protection of inert gas for reaction to prepare up-conversion nanoparticles containing oleic acid ligands; wherein oleic acid is used as ligand, 1-octadecene is used as solvent, and fluorine source can adopt ammonium fluoride (NH)4F) Trifluoroacetic acid, hydrogen fluoride, etc., and the inert gas can be nitrogen, helium, neon, argon, krypton, etc.; after the reaction is finished, the product can be precipitated by absolute ethyl alcohol, centrifugally cleaned by a mixed solution of cyclohexane and ethyl alcohol and then re-dispersed in cyclohexane;
the second step specifically comprises: dispersing the upconversion nanoparticles containing oleic acid ligands in acid liquor, removing the oleic acid ligands, then dispersing in water again, and adding polyelectrolyte for reaction to prepare the polyelectrolyte-modified upconversion nanoparticles. Wherein, the acid solution can adopt a hydrochloric acid solution, and specifically can adopt a hydrochloric acid solution with the pH value of 2-4; the mass ratio of the upconversion nanoparticles containing the oleic acid ligand to the polyelectrolyte is generally controlled to be 1: (1-30), preferably 1: 20.
In step S2, a polyelectrolyte layer (e.g., polyethyleneimine PEI, sodium polystyrene sulfonate PSS, etc.) may be spin-coated on the electrode, and then the polyelectrolyte-modified upconversion nanoparticles and the gas-sensitive sensing material are sequentially spin-coated thereon.
In a third aspect of the present invention, a gas-sensitive electrode is provided, which includes a base electrode and any one of the near-infrared light gain gas sensing films provided in the first aspect of the present invention, where the near-infrared light gain gas sensing film is provided on a surface of the base electrode. The base electrode may be an interdigital electrode. During preparation, the polyelectrolyte-modified upconversion nanoparticles and the gas-sensitive sensing material can be directly and sequentially arranged on the base electrode in a laminating manner to form an upconversion nanoparticle layer and a gas-sensitive sensing material layer.
In a fourth aspect of the invention, a sensor is provided, comprising any one of the gas sensing electrodes provided in the third aspect of the invention. The sensor can also comprise a near infrared light source which is used for providing near infrared light irradiation to the gas-sensitive electrode during detection; the wavelength of the infrared light emitted by the near infrared light source is 980nm, and the light intensity can be 1-100 Mw/cm2. In addition, the sensor can also comprise a detection device, wherein the detection device is connected with the gas-sensitive electrode and is used for detecting the conductance change of the gas-sensitive electrode to the detection gas under the irradiation of near infrared light so as to further detect the gas content.
Drawings
The invention is further described with reference to the following figures and examples, in which:
FIG. 1 is the NaYF nanoparticle modified by sodium polystyrene sulfonate in example 14A schematic flow chart of the preparation of 30Yb,2Er @ PSS;
FIG. 2 is a schematic diagram of a process for preparing a near infrared light gain gas sensing film Er @ PSS-rGO in example 1;
FIG. 3 shows NaYF4:30Yb,2Er @ OA, NaYF4:30Yb,2Er @ PSS in example 1 and NaYF4:50Yb,2Tm @ OA, NaYF in example 24TEM image of 50Yb,2Tm @ PSS, and upconversion luminescence image of NaYF4:30Yb,2Er @ OA, NaYF4:50Yb,2Tm @ OA;
FIG. 4 shows NaYF in example 1430Yb,2Er @ OA and NaYF4An infrared spectrogram of 30Yb,2Er @ PSS;
FIG. 5 is the NaYF of the upper conversion nanoparticle layer in example 14SEM images of a 30Yb,2Er @ PSS layer, a near infrared light gain gas sensing film Er @ PSS-rGO, and a gas sensing material rGO/ZnO and a near infrared light gain gas sensing film Tm @ PSS-rGO/ZnO in example 2;
FIG. 6 shows the graphene (rGO), graphene/zinc oxide composite (rGO/ZnO) and molybdenum disulfide/zinc oxide composite (MoS) in examples 1-32ZnO), and NaYF in examples 1 to 2430Yb,2Er @ PSS and NaYF4A fluorescence emission spectrum of 50Yb,2Tm @ PSS;
FIG. 7 is a gas-sensitive test curve of the near-infrared light gain gas sensing film Er @ PSS-rGO prepared in example 1 under the conditions of drying (30 RH%) and humidity (75 RH%) and adding 980nm light for 25ppm formaldehyde respectively;
FIG. 8 is a graph showing the results of three cycle stability tests of the near infrared light gain gas sensing film Tm @ PSS-rGO/ZnO prepared in example 2 on 1ppm formaldehyde under 980nm laser irradiation;
FIG. 9 shows the Tm @ PSS-MoS of the near-infrared light gain gas sensor film obtained in example 32A test result graph of three circulation stability of ZnO to 1ppm formaldehyde under 980nm laser irradiation;
FIG. 10 is a Tm @ OA-MoS gas sensor film obtained in comparative example 12A gas sensing test result graph of 1ppm formaldehyde by ZnO under 980nm laser irradiation;
FIG. 11 is a graph of the gas sensing test results of the gas sensing thin film rGO/ZnO prepared in comparative example 2 on 1ppm formaldehyde under 980nm laser irradiation.
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
The embodiment prepares a near-infrared light gain gas sensing film, and the specific preparation process comprises the following steps:
s1, preparing oleic acid ligand-containing up-conversion nanoparticles UCNPs @ OA (specifically NaYF) by adopting solvothermal method430Yb,2Er @ OA) and comprises the following specific preparation processes:
3.4mL of yttrium acetate (Y (C)2H3O2)3·6H2O, 0.2M), 1.5mL of ytterbium acetate (Yb (C)2H3O2)3·6H2O, 0.2M) and 0.1mL of erbium acetate (Er (C)2H3O2)3·6H2O, 0.2M), 17.5mL of octadecene and 7.5mL of oleic acid were added to a 100mL three-necked flask, and the mixture was magnetically stirred at 150 ℃ for 1 hour by using a temperature-controlled electric heating mantle, and then after the temperature was lowered to 70 ℃, 15mL of NaOH and NH were rapidly added4Methanol mixture of F (NaOH and NH)4The molar ratio of F was 5:8), the temperature was kept at 40 ℃ and stirring was carried out for 3 h. Then raising the reaction temperature to 100 ℃ to remove methanol and water, raising the temperature of the reaction system to 300 ℃ under the protection of argon atmosphere by vacuumizing and introducing argon for three times, reacting for 1.5h, cooling the reaction to room temperature after the reaction is finished, precipitating the product by 10mL of absolute ethyl alcohol, centrifuging by using a mixed solution of cyclohexane and ethanol (the volume ratio is 1:2), centrifuging (7500rpm, 5min), cleaning for three times until the supernatant is colorless, and re-dispersing in 8mL of cyclohexane to obtain Yb3+，Er3+Co-doped upconversion nanoparticles containing oleic acid ligands, noted NaYF430Yb,2Er @ OA, the upconversion luminescence picture is shown as the inset in FIG. 3 (a).
S2 preparation of sodium polystyrene sulfonate modified upconversion by ligand exchange methodNanoparticle NaYF430Yb,2Er @ PSS, as shown in FIG. 1, comprising:
dispersing 2mL of the upconversion nanoparticles containing the oleic acid ligand prepared in the step S1 in 30mL of hydrochloric acid solution (pH 2), performing ultrasonic treatment for 45min, centrifuging at 13000r/min for 10min, removing the supernatant, then re-dispersing in 30mL of hydrochloric acid solution (pH 2), adding 2mL of cyclohexane, performing ultrasonic treatment for 10min, centrifuging at 13000r/min for 10min, repeating the steps for 2 times to completely remove the oleic acid ligand, re-dispersing the precipitate in 5mL of deionized water to obtain ligand-removed upconversion nanoparticle dispersion, which is marked as NaYF430Yb,2 Er-free. Then, 40mL of sodium polystyrene sulfonate solution (PSS, 2.5mg/mL) is rapidly added into the dispersion liquid of the up-conversion nanoparticles after the ligand is removed, the mixture is stirred for 1h, the product is centrifuged for 10min at 10000r/min, the centrifugation is repeated for 2 times to remove the free sodium polystyrene sulfonate, and then the product is re-dispersed in 8mL of deionized water, so that the up-conversion nanoparticles modified by the sodium polystyrene sulfonate are obtained and marked as NaYF4:30Yb,[email protected]。
S3, dissolving 92mg of 5-amino-1-naphthalenesulfonic Acid (ANS) in 10mL of deionized water, adding 4mL of graphene oxide dispersion liquid (1mg/mL), adding 10mL of hydrazine hydrate (1.12 mu L/mL) reducing agent into the mixed solution, reacting for 1 hour at 80 ℃, fully assembling ANS with graphene through pi-pi interaction, completely reducing, filtering the product to remove redundant reducing agent and free ANS, and obtaining the ANS function modified reduced graphene oxide of the gas-sensitive sensing material, wherein the reduced graphene oxide is marked as rGO.
S4, as shown in figure 2, sequentially spin-coating polyethyleneimine PEI and sodium polystyrene sulfonate PSS on the surface of the interdigital electrode to prepare a polyelectrolyte layer; then spin-coating the sodium polystyrene sulfonate modified up-conversion nano-particle NaYF prepared in the step S2 on the polyelectrolyte layer430Yb,2Er @ PSS, to produce an Up-converted nanoparticle layer (UCNPs @ PSS layer, i.e., NaYF430Yb,2Er @ PSS layer); and spinning a polyelectrolyte PEI layer on the upper conversion nanoparticle layer, then spinning the gas-sensitive sensing material rGO prepared in the step S3 to prepare a gas-sensitive sensing material layer (rGO layer), and further forming a near infrared light gain gas sensing film on the surface of the interdigital electrode, wherein the near infrared light gain gas sensing film is recorded as Er @ PSS-rGO.
In the preparation process of the near-infrared light gain gas sensing film, the polyelectrolyte layer is arranged on the interdigital electrode, so that the surface of the electrode can be positively charged, and the negatively charged up-conversion nanoparticles UCNPs @ PSS are facilitated-Better coating and dispersion; a layer of polyelectrolyte PEI was placed on the upconversion nanoparticle layer to serve a similar function. Of course, in other embodiments, the provision of the above polyelectrolyte layer may be eliminated. The near-infrared light gain gas sensing film prepared by the method comprises an up-conversion nano particle layer (NaYF) arranged in a stacked manner430Yb,2Er @ PSS layer) and a gas sensitive sensing material layer (rGO layer); the interdigital electrode and the near infrared light gain gas sensing film arranged on the surface of the interdigital electrode are combined to form a gas-sensitive electrode.
Example 2
The embodiment prepares a near-infrared light gain gas sensing film, and the specific preparation process comprises the following steps:
s1, preparing up-conversion nanoparticles NaYF containing oleic acid ligands by adopting solvothermal method450Yb,2Tm @ OA, and the preparation process comprises the following steps:
2.4mL of yttrium acetate (Y (C)2H3O2)3·6H2O, 0.2M), 2.5mL of ytterbium acetate (Yb (C)2H3O2)3·6H2O, 0.2M), 0.1mL erbium acetate (Tm (C)2H3O2)3·6H2O, 0.2M), 17.5mL of octadecene and 7.5mL of oleic acid were added to a 100mL three-necked flask, and the mixture was magnetically stirred at 150 ℃ for 1 hour by using a temperature-controlled electric heating mantle, and then after the temperature was lowered to 70 ℃, 15mL of NaOH and NH were rapidly added4Methanol mixture of F (NaOH and NH)4The molar ratio of F was 5:8), the temperature was kept at 40 ℃ and stirring was carried out for 2 h. Then raising the reaction temperature to 100 ℃ to remove methanol and water, raising the temperature of the reaction system to 300 ℃ under the protection of argon atmosphere by vacuumizing and introducing argon for three times, reacting for 1.5h, cooling the reaction to room temperature after the reaction is finished, precipitating the product by 10mL of absolute ethyl alcohol, centrifuging by using a mixed solution of cyclohexane and ethanol (the volume ratio is 1:2), centrifuging (7500rpm, 5min), cleaning for three times until the supernatant is colorless, and re-dispersing in 8mL of cyclohexane to obtain the productYb3+，Tm3+Co-doped upconversion nanoparticles containing oleic acid ligands, noted NaYF450Yb,2Tm @ OA, the upconverted luminescence picture is shown as the inset in FIG. 3 (c).
S2 preparation of sodium polystyrene sulfonate modified up-conversion nanoparticles NaYF by ligand exchange method450Yb,2Tm @ PSS comprising:
dispersing 2mL of the upconversion nanoparticles containing the oleic acid ligand prepared in the step S1 in 30mL of hydrochloric acid solution (pH is 2), performing ultrasonic treatment for 45min, centrifuging at 13000r/min for 10min, repeating the step for 2 times to completely remove the oleic acid ligand, re-dispersing the precipitate in 5mL of deionized water to obtain an upconversion nanoparticle dispersion solution without the ligand, which is marked as NaYF450Yb,2Tm @ free. Then, 40mL of sodium polystyrene sulfonate solution (PSS, 2.5mg/mL) is rapidly added into the dispersion liquid of the up-conversion nanoparticles after the ligand is removed, the mixture is stirred for 1h, the product is centrifuged for 10min at 10000r/min, the centrifugation is repeated for 2 times to remove the free sodium polystyrene sulfonate, and then the product is re-dispersed in 8mL of deionized water, so that the up-conversion nanoparticles modified by the sodium polystyrene sulfonate are obtained and marked as NaYF4:50Yb,[email protected]。
S3, dissolving 92mg of 5-amino-1-naphthalenesulfonic Acid (ANS) in 10mL of deionized water, adding 4mL of graphene oxide dispersion liquid (1mg/mL), adding 10mL of hydrazine hydrate (1.12 muL/mL) reducing agent into the mixed solution, reacting for 1 hour at 80 ℃, fully assembling ANS with graphene through pi-pi interaction, completely reducing, filtering the product to remove redundant reducing agent and free ANS to obtain reduced graphene oxide (rGO) with ANS function modification, dispersing the reduced graphene oxide (rGO) and 400mg of zinc oxide nanoparticles (obtained from the market) into 10mL of deionized water (the mass ratio of zinc oxide to graphene is 100: 1), and carrying out intense ultrasonic treatment on the mixed solution for 1 hour to obtain supramolecular assembly dispersion liquid A; and drying the mixture in a vacuum oven at 70 ℃ for 6 hours to obtain a product B, namely the gas-sensitive sensing material, which is recorded as rGO/ZnO.
S4, sequentially spin-coating polyethyleneimine PEI and sodium polystyrene sulfonate PSS on the surface of the interdigital electrode to prepare a polyelectrolyte layer; then spin-coating the polystyrene sodium sulfonate modified up-conversion nano-particles prepared in the step S2 on the polyelectrolyte layerGranular NaYF450Yb,2Tm @ PSS to prepare an upper conversion nanoparticle layer; and spin-coating the gas-sensitive sensing material graphene/zinc oxide composite material prepared in the step S3 on the upper conversion nanoparticle layer to prepare a gas-sensitive sensing material layer (rGO/ZnO layer), and further forming a near-infrared light gain gas sensing film on the surface of the interdigital electrode, wherein the near-infrared light gain gas sensing film is marked as Tm @ PSS-rGO/ZnO. The near-infrared light gain gas sensing film comprises an up-conversion nanoparticle layer (namely NaYF) arranged in a laminated mode450Yb,2Tm @ PSS layer) and a gas sensitive sensing material layer (rGO/ZnO layer); the interdigital electrode and the near infrared light gain gas sensing film arranged on the surface of the interdigital electrode are combined to form a gas-sensitive electrode.
Example 3
The embodiment prepares a near-infrared light gain gas sensing film, and the specific preparation process comprises the following steps:
s1, preparing up-conversion nanoparticles NaYF containing oleic acid ligands by adopting solvothermal method450Yb,2Tm @ OA, and the preparation process comprises the following steps:
2.4mL of yttrium acetate (Y (C)2H3O2)3·6H2O, 0.2M), 2.5mL of ytterbium acetate (Yb (C)2H3O2)3·6H2O, 0.2M), 0.1mL erbium acetate (Tm (C)2H3O2)3·6H2O, 0.2M), 17.5mL of octadecene and 7.5mL of oleic acid were added to a 100mL three-necked flask, and the mixture was magnetically stirred at 150 ℃ for 1 hour by using a temperature-controlled electric heating mantle, and then after the temperature was lowered to 70 ℃, 15mL of NaOH and NH were rapidly added4Methanol mixture of F (NaOH and NH)4The molar ratio of F was 5:8), the temperature was kept at 40 ℃ and stirring was carried out for 2 h. Then raising the reaction temperature to 100 ℃ to remove methanol and water, raising the temperature of the reaction system to 300 ℃ under the protection of argon atmosphere by vacuumizing and introducing argon for three times, reacting for 1.5h, cooling the reaction to room temperature after the reaction is finished, precipitating the product by 10mL of absolute ethyl alcohol, centrifuging by using a mixed solution of cyclohexane and ethanol (volume ratio of 1:2), centrifuging (7500rpm, 5min), cleaning for three times until the supernatant is colorless, and re-dispersing in 8mL of cyclohexane to obtain Yb3+，Tm3+Co-doped upconversion nanoparticles containing oleic acid ligands, noted NaYF4:50Yb,[email protected]。
S2 preparation of sodium polystyrene sulfonate modified up-conversion nanoparticles NaYF by ligand exchange method450Yb,2Tm @ PSS comprising:
dispersing 2mL of the upconversion nanoparticles containing the oleic acid ligand prepared in the step S1 in 30mL of hydrochloric acid solution (pH is 2), performing ultrasonic treatment for 45min, centrifuging at 13000r/min for 10min, repeating the step for 2 times to completely remove the oleic acid ligand, re-dispersing the precipitate in 5mL of deionized water to obtain an upconversion nanoparticle dispersion solution without the ligand, which is marked as NaYF450Yb,2Tm @ free. Then, 40mL of sodium polystyrene sulfonate solution (PSS, 2.5mg/mL) is rapidly added into the dispersion liquid of the up-conversion nanoparticles after the ligand is removed, the mixture is stirred for 1h, the product is centrifuged for 10min at 10000r/min, the centrifugation is repeated for 2 times to remove the free sodium polystyrene sulfonate, and then the product is re-dispersed in 8mL of deionized water, so that the up-conversion nanoparticles modified by the sodium polystyrene sulfonate are obtained and marked as NaYF4:50Yb,[email protected]。
S3, sequentially spin-coating polyethyleneimine PEI and sodium polystyrene sulfonate PSS on the surface of the interdigital electrode to prepare a polyelectrolyte layer; then spin-coating the sodium polystyrene sulfonate modified up-conversion nano-particle NaYF prepared in the step S2 on the polyelectrolyte layer450Yb,2Tm @ PSS to prepare an upper conversion nanoparticle layer; and then, a gas-sensitive sensing material molybdenum disulfide/zinc oxide composite material is spin-coated on the upper conversion nanoparticle layer to prepare a gas-sensitive sensing material layer (MoS)2a/ZnO layer) and further forming a near infrared light gain gas sensing film on the surface of the interdigital electrode, wherein the near infrared light gain gas sensing film is marked as Tm @ PSS-MoS2and/ZnO. The near-infrared light gain gas sensing film comprises an up-conversion nano particle layer (NaYF) which is arranged in a laminated mode430Yb,2Er @ PSS layer) and gas sensitive sensing material layer (MoS)2a/ZnO layer); the interdigital electrode and the near infrared light gain gas sensing film arranged on the surface of the interdigital electrode are combined to form a gas-sensitive electrode.
Comparative example 1
The comparative example prepares a gas sensing film, and the specific preparation process comprises the following steps:
s1, preparing up-conversion nanoparticles NaYF containing oleic acid ligands by adopting solvothermal method450Yb,2Tm @ OA, preparationThe preparation process comprises the following steps:
2.4mL of yttrium acetate (Y (C)2H3O2)3·6H2O, 0.2M), 2.5mL of ytterbium acetate (Yb (C)2H3O2)3·6H2O, 0.2M), 0.1mL erbium acetate (Tm (C)2H3O2)3·6H2O, 0.2M), 17.5mL of octadecene and 7.5mL of oleic acid were added to a 100mL three-necked flask, and the mixture was magnetically stirred at 150 ℃ for 1 hour by using a temperature-controlled electric heating mantle, and then after the temperature was lowered to 70 ℃, 15mL of NaOH and NH were rapidly added4Methanol mixture of F (NaOH and NH)4The molar ratio of F was 5:8), the temperature was kept at 40 ℃ and stirring was carried out for 2 h. Then raising the reaction temperature to 100 ℃ to remove methanol and water, raising the temperature of the reaction system to 300 ℃ under the protection of argon atmosphere by vacuumizing and introducing argon for three times, reacting for 1.5h, cooling the reaction to room temperature after the reaction is finished, precipitating the product by 10mL of absolute ethyl alcohol, centrifuging by using a mixed solution of cyclohexane and ethanol (volume ratio of 1:2), centrifuging (7500rpm, 5min), cleaning for three times until the supernatant is colorless, and re-dispersing in 8mL of cyclohexane to obtain Yb3+，Tm3+Co-doped upconversion nanoparticles containing oleic acid ligands, noted NaYF4:50Yb,[email protected]。
S2, sequentially spin-coating polyethyleneimine PEI and sodium polystyrene sulfonate PSS on the surface of the interdigital electrode to prepare a polyelectrolyte layer; then spin-coating the upconversion nanoparticle NaYF containing the oleic acid ligand prepared in the step S1 on the polyelectrolyte layer450Yb,2Tm @ OA to prepare an upper converted nanoparticle layer; and then, a gas-sensitive sensing material molybdenum disulfide/zinc oxide composite material is spin-coated on the upper conversion nanoparticle layer to prepare a gas-sensitive sensing material layer (MoS)2/ZnO layer) and a gas sensing thin film, recorded as Tm @ OA-MoS, is formed on the fork-shaped electrode2and/ZnO. The gas sensing film includes a layer of upconverting nanoparticles (NaYF) disposed in a stack430Yb,2Tm @ OA layer) and a gas sensitive sensing material layer (MoS)2a/ZnO layer); the interdigital electrode and the gas sensing film arranged on the surface of the interdigital electrode are combined to form the gas-sensitive electrode.
Comparative example 2
The comparative example prepares a gas sensing film, and the specific preparation process comprises the following steps:
s1, dissolving 92mg of 5-amino-1-naphthalenesulfonic Acid (ANS) in 10mL of deionized water, adding 4mL of graphene oxide dispersion liquid (1mg/mL), adding 10mL of hydrazine hydrate (1.12 muL/mL) reducing agent into the mixed solution, reacting at 80 ℃ for 1 hour to ensure that the ANS is fully assembled with graphene through pi-pi interaction and is completely reduced, filtering the product to remove redundant reducing agent and free ANS to obtain reduced graphene oxide (rGO) with ANS function modification, dispersing the reduced graphene oxide (rGO) and 400mg of zinc oxide nanoparticles (obtained from the market) into 10mL of deionized water together (the mass ratio of zinc oxide to graphene is 100: 1), and carrying out intense ultrasonic treatment on the mixed solution for 1 hour to obtain the supermolecular assembly dispersion liquid A. And drying the mixture in a vacuum oven at 70 ℃ for 6 hours to obtain a product B, namely the gas-sensitive sensing material, which is recorded as rGO/ZnO.
S2, sequentially spin-coating polyethyleneimine PEI and sodium polystyrene sulfonate PSS on the surface of the interdigital electrode to prepare a polyelectrolyte layer; and then spin-coating a gas-sensitive sensing material rGO/ZnO composite material on the polyelectrolyte layer to prepare a gas-sensitive sensing material layer (rGO/ZnO layer), and further forming a gas sensing film on the fork-shaped electrode. The interdigital electrode and the gas sensing film arranged on the surface of the interdigital electrode are combined to form the gas-sensitive electrode.
Test examples
The NaYF prepared in step S1 of example 1 was respectively treated with a projection electron microscope (TEM)430Yb,2Er @ OA, NaYF prepared in step S2430Yb,2Er @ PSS, and NaYF prepared in step S1 of example 2450Yb,2Tm @ OA and NaYF prepared in step S2450Yb,2Tm @ PSS, the morphologies of the samples were shown in FIGS. 3 (a) to (d), and the insert in the upper right corner of FIG. 3 (a) is NaYF430Yb,2Er @ OA upconverted luminescent picture, and (c) the insert in the upper right corner is NaYF4An upconversion luminescence picture of 50Yb,2Tm @ OA. The results shown in (a), (b) of FIG. 3 show the sodium polystyrene sulfonate modified up-conversion nanoparticles NaYF of example 14The thickness of the sodium polystyrene sulfonate (PSS) coating layer in 30Yb,2Er @ PSS is about 2.5-5 nm. The results shown in (c) and (d) in FIG. 3 show the sodium polystyrene sulfonate modified up-conversion nanoparticles NaYF of example 24The thickness of the sodium polystyrene sulfonate (PSS) coating layer in 50Yb,2Tm @ PSS is about 1 to 3 nm.
In addition, the upconversion nanoparticles NaYF containing oleic acid ligand in example 1 were separately prepared430Yb,2Er @ OA and sodium polystyrene sulfonate modified upconversion nano-particle NaYF4FIG. 4 shows the results of IR spectroscopy on 30Yb,2Er @ PSS, and the results in FIG. 4 show that PSS has been successfully coated.
Scanning electron microscope was used to separately align the up-converted nanoparticle layer NaYF prepared in example 14SEM tests were carried out on 30Yb,2Er @ PSS layer, near infrared light gain gas sensing film Er @ PSS-rGO, and the gas sensitive sensing material rGO/ZnO and the prepared near infrared light gain gas sensing film Tm @ PSS-rGO/ZnO in example 2, and the obtained results are shown in FIG. 5. FIG. 5 (b) is an SEM image of the Er @ PSS-rGO layer, where it can be seen that the graphene sheets with folds spread flat on the upper converted nanoparticle layer, demonstrating the successful combination of graphene and upper converted nanoparticles; FIG. 5 (d) is an SEM image of Tm @ PSS-rGO/ZnO layer, and it can be seen that the upconversion nanoparticles are tightly combined with the rGO/ZnO gas-sensitive material, so that a good structural support is provided for realizing enhanced gas-sensitive performance.
Respectively comparing the graphene (rGO), the graphene/zinc oxide composite material (rGO/ZnO) and the molybdenum disulfide/zinc oxide composite material (MoS) adopted in the embodiments 1 to 32ZnO), and NaYF prepared in examples 1 to 2430Yb,2Er @ PSS and NaYF4The fluorescence emission spectra of 50Yb,2Tm @ PSS were examined and their emission/absorption wavelengths were observed to overlap, and the results are shown in FIG. 6. As can be seen from FIG. 6, NaYF430Yb,2Er @ PSS has stronger emission in visible light regions of 410nm and 530-570nm, and has larger overlap with the ultraviolet visible light absorption spectrum of rGO; NaYF450Yb,2Tm @ PSS has strong emission in the visible light region of 450nm and 477nm, and is combined with rGO/ZnO and MoS2The ultraviolet and visible light absorption spectra of the/ZnO have large overlap.
The gas-sensitive electrode prepared by the method can be further used for preparing a gas-sensitive sensor, and the invention further provides a sensor which comprises any one of the gas-sensitive electrodes, wherein the sensor can be matched with an external near infrared light source and a detection device for use when detecting gas to be detected so as to provide near infrared light irradiation for the gas-sensitive electrode by the near infrared light source during detection; and the detection device is connected with the gas-sensitive electrode and is used for detecting the conductance change of the gas-sensitive electrode to the gas to be detected under the irradiation of near infrared light, so as to further detect the gas content. Of course, one or both of the near infrared light source and the detection device may be used as a component of the sensor itself.
When the gas-sensitive electrode is applied to gas-sensitive detection, the operation can be specifically carried out according to the following steps:
irradiating a near-infrared light source with the wavelength of 980nm onto a near-infrared light gain gas sensing film on the surface of the interdigital electrode, and adjusting the light source density to be 10mW/cm2And the interdigital electrode is connected to a detection device, 20V bias voltage is provided for the interdigital electrode, and gas-sensitive detection is carried out under 980nm near infrared light irradiation.
The gas electrode prepared in example 1 was used to detect HCHO gas at a concentration of 25ppm under irradiation of dry (humidity 30 RH%) and wet (humidity 75 RH%) with 980nm near infrared light according to a gas detection method similar to the above method, and the results are shown in fig. 7. As can be seen from fig. 7, the response value of the gas-sensitive electrode (or what can be understood as a near infrared light gain gas sensing film) in example 1 to 25ppm of HCHO gas is as high as 1.31 in a dry environment of 30 RH%, and it has a humidity resistance characteristic that the response value is maintained as much as that in the dry condition (30 RH%) even in a humid environment of up to 75 RH%.
In addition, gas sensing tests were performed on HCHO gas at a concentration of 1ppm under 980nm laser irradiation (except for special descriptions, performance tests were performed at room temperature with humidity of about 30 RH%) using the gas-sensitive electrodes prepared in examples 2 and 3 and comparative examples 1 and 2, respectively, according to a gas-sensitive detection method similar to the above, and the results are shown in fig. 8 to 11. As can be seen from fig. 8 and 11, the response value of the gas-sensitive electrode (or the near infrared light gain gas sensing film) in example 2 to 1ppm of HCHO gas is as high as 2.5, which can significantly improve the sensitivity of the sensor and has good cycle stability compared to that in comparative example 2 (1.19); FIG. 9 shows that the response value of the gas sensitive electrode (or near infrared light gain gas sensing film) in example 3 to 1ppm HCHO gas is as high as 1.35, and the cycle stability is good; FIG. 10 shows that the response value of the gas-sensitive electrode (or near-infrared light gain gas sensing film) in comparative example 1 to 1ppm of HCHO gas was 1.16.
By the preparation method, the gas-sensitive sensing material can be well combined with the up-conversion nano particles to form a compact near-infrared light gain gas sensing film, and the near-infrared light gain gas sensing film can widen the light source of the photo-catalytically activated gas-sensitive sensing material layer to a near-infrared region by introducing the up-conversion nano particle layer, so that the near-infrared photo-catalytically activated gas sensing with longer wavelength, high penetrating power and no harm to the body is utilized, the detection limit can be reduced, and the sensitivity is remarkably improved; in addition, the preparation method of the near-infrared light gain gas sensing film is simple and suitable for large-scale production.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.