CN115128138A - Gold nanoparticle modified nickel molybdate nanocomposite and preparation method thereof - Google Patents
Gold nanoparticle modified nickel molybdate nanocomposite and preparation method thereof Download PDFInfo
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- NLPVCCRZRNXTLT-UHFFFAOYSA-N dioxido(dioxo)molybdenum;nickel(2+) Chemical class [Ni+2].[O-][Mo]([O-])(=O)=O NLPVCCRZRNXTLT-UHFFFAOYSA-N 0.000 title claims abstract description 128
- 239000002114 nanocomposite Substances 0.000 title claims abstract description 46
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 43
- 239000010931 gold Substances 0.000 title claims abstract description 43
- 239000002105 nanoparticle Substances 0.000 title claims abstract description 32
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 31
- 238000002360 preparation method Methods 0.000 title abstract description 17
- 239000000463 material Substances 0.000 claims abstract description 94
- 238000000034 method Methods 0.000 claims abstract description 54
- 239000002077 nanosphere Substances 0.000 claims abstract description 48
- 239000011259 mixed solution Substances 0.000 claims abstract description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 30
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 29
- 238000003756 stirring Methods 0.000 claims abstract description 27
- 239000008367 deionised water Substances 0.000 claims abstract description 24
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 24
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 19
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000004202 carbamide Substances 0.000 claims abstract description 13
- 238000001354 calcination Methods 0.000 claims abstract description 12
- 238000005406 washing Methods 0.000 claims abstract description 11
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 9
- 238000001291 vacuum drying Methods 0.000 claims abstract description 6
- 238000005303 weighing Methods 0.000 claims abstract description 5
- 239000002131 composite material Substances 0.000 claims abstract description 3
- 239000007789 gas Substances 0.000 claims description 188
- 239000000243 solution Substances 0.000 claims description 41
- 239000011734 sodium Substances 0.000 claims description 32
- -1 gold nanoparticle-modified nickel molybdate Chemical class 0.000 claims description 23
- 238000001514 detection method Methods 0.000 claims description 11
- 238000009835 boiling Methods 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 239000002253 acid Substances 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 7
- 238000006722 reduction reaction Methods 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 3
- 229920006316 polyvinylpyrrolidine Polymers 0.000 claims description 3
- 238000004090 dissolution Methods 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims 3
- 229910052782 aluminium Inorganic materials 0.000 claims 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims 2
- 239000011777 magnesium Substances 0.000 claims 2
- 229910052749 magnesium Inorganic materials 0.000 claims 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims 1
- 229910052802 copper Inorganic materials 0.000 claims 1
- 239000010949 copper Substances 0.000 claims 1
- 239000011591 potassium Substances 0.000 claims 1
- 229910052700 potassium Inorganic materials 0.000 claims 1
- 229910052760 oxygen Inorganic materials 0.000 abstract description 22
- 239000004065 semiconductor Substances 0.000 abstract description 15
- 239000007795 chemical reaction product Substances 0.000 abstract description 4
- 230000009467 reduction Effects 0.000 abstract description 3
- 239000001509 sodium citrate Substances 0.000 abstract description 3
- HRXKRNGNAMMEHJ-UHFFFAOYSA-K trisodium citrate Chemical compound [Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O HRXKRNGNAMMEHJ-UHFFFAOYSA-K 0.000 abstract description 3
- 229940038773 trisodium citrate Drugs 0.000 abstract description 3
- 239000006172 buffering agent Substances 0.000 abstract description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 54
- 230000035945 sensitivity Effects 0.000 description 38
- 238000012360 testing method Methods 0.000 description 30
- 238000006243 chemical reaction Methods 0.000 description 21
- 230000000694 effects Effects 0.000 description 21
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- 239000001301 oxygen Substances 0.000 description 18
- 230000005684 electric field Effects 0.000 description 12
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 12
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 12
- 230000004044 response Effects 0.000 description 12
- 238000000137 annealing Methods 0.000 description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 239000000203 mixture Substances 0.000 description 11
- 238000006479 redox reaction Methods 0.000 description 11
- 238000011084 recovery Methods 0.000 description 10
- 239000004094 surface-active agent Substances 0.000 description 10
- 238000007254 oxidation reaction Methods 0.000 description 9
- 230000004048 modification Effects 0.000 description 8
- 238000012986 modification Methods 0.000 description 8
- 230000002829 reductive effect Effects 0.000 description 8
- 239000002360 explosive Substances 0.000 description 7
- 239000012535 impurity Substances 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 7
- 239000003054 catalyst Substances 0.000 description 6
- 230000008859 change Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 229910017855 NH 4 F Inorganic materials 0.000 description 5
- 230000009471 action Effects 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 238000005286 illumination Methods 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- 238000012512 characterization method Methods 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 238000011946 reduction process Methods 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 238000002198 surface plasmon resonance spectroscopy Methods 0.000 description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 3
- 239000000872 buffer Substances 0.000 description 3
- 239000012153 distilled water Substances 0.000 description 3
- 239000012154 double-distilled water Substances 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000001132 ultrasonic dispersion Methods 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 229910018661 Ni(OH) Inorganic materials 0.000 description 2
- 229910005809 NiMoO4 Inorganic materials 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 238000013329 compounding Methods 0.000 description 2
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Inorganic materials [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 229940116411 terpineol Drugs 0.000 description 2
- 229910000314 transition metal oxide Inorganic materials 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000002784 hot electron Substances 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002082 metal nanoparticle Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 229910001453 nickel ion Inorganic materials 0.000 description 1
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 1
- 238000005839 oxidative dehydrogenation reaction Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 238000011896 sensitive detection Methods 0.000 description 1
- 230000001235 sensitizing effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
- G01N27/125—Composition of the body, e.g. the composition of its sensitive layer
- G01N27/127—Composition of the body, e.g. the composition of its sensitive layer comprising nanoparticles
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Nanotechnology (AREA)
- Chemical Kinetics & Catalysis (AREA)
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Abstract
The application relates to the technical field of semiconductor gas sensitive devices, and particularly provides a gold nanoparticle modified nickel molybdate nano composite material and a preparation method thereof. The composite material comprises spherical nickel molybdate and gold nanoparticles, wherein the gold nanoparticles are fixedly distributed on the surface of the spherical nickel molybdate. The method comprises the following steps: s1, preparing nickel molybdate nanospheres; s2, preparing the gold nanoparticle modified nickel molybdate nano composite material. Step S1 includes weighing Ni (NO) 3 ) 2 ·6H 2 O and Na 2 MoO 4 ·2H 2 Dissolving O in deionized water, adding urea and NH after completely dissolving 4 F, continuously stirring until a uniform mixed solution is formed, then transferring the mixed solution into a hydrothermal reaction kettle for hydrothermal reaction, centrifuging, washing and vacuum-drying a hydrothermal reaction product, and finally calcining the hydrothermal reaction product in air to obtain NiMoO 4 Nanospheres; step S2 reduction of HAuCl with trisodium citrate 4 Gold nanoparticles are directly generated on the surface of the nickel molybdate nanosphere, and PVP is used as a buffering agent.
Description
Technical Field
The application relates to the technical field of semiconductor gas sensitive devices, in particular to a gold nanoparticle modified nickel molybdate nano composite material and a preparation method thereof.
Background
The resistance type gas-sensitive device carries out chemical reaction on gas to be detected and a gas-sensitive material, and converts the type and the concentration of the gas to be detected into the change of the resistance of the gas-sensitive device, so that the aim of carrying out sensitive detection on the gas to be detected is fulfilled. The gas sensitive device can be used for detecting ppm-level toxic and harmful gases and can also be used for detecting flammable and explosive gases with high percentage concentration.
During detection, in an air environment, oxygen is adsorbed on the surface of the semiconductor gas-sensitive material, electrons in the semiconductor gas-sensitive material are captured, oxygen anions are formed, the resistance of the gas-sensitive device is increased, when reducing gases to be detected, such as ethanol, carbon monoxide, methane, hydrogen and other combustible gases, oxidation-reduction reaction is carried out on the surface of the semiconductor gas-sensitive material and the oxygen anions, a large number of electrons are released to enter a conduction band of the semiconductor gas-sensitive material, the resistance of the gas-sensitive device is reduced, and the purpose of detection is achieved. The sensitivity of the gas sensitive device is a measurement standard of the gas sensitive performance of the gas sensitive device, and the higher the sensitivity of the gas sensitive device is, the better the gas sensitive characteristic is, and the sensitivity is closely related to the gas sensitive material of the gas sensitive device.
The improvement of the sensitivity of the traditional semiconductor resistance type gas sensitive device is generally realized by increasing the activity of air and gas to be detected, namely the working temperature of the traditional semiconductor resistance type gas sensitive device is higher and is mostly about 350 ℃, so that the service life of the gas sensitive device is greatly shortened, the application range of the gas sensitive device is severely limited, and the flammable and explosive gas is difficult to be safely and effectively detected. In addition, the conventional semiconductor resistance type gas sensitive device has poor selectivity to a specific gas.
In conclusion, the gas sensitive device prepared based on the existing gas sensitive material has low sensitivity at room temperature, is difficult to be used for detecting flammable and explosive gases, and has poor selectivity.
Disclosure of Invention
The present invention aims to provide a gold nanoparticle modified nickel molybdate nanocomposite and a preparation method thereof, aiming at the defects in the prior art. The novel gas sensitive material and the preparation method thereof are disclosed to solve the problems that a gas sensitive device prepared based on the existing gas sensitive material has low sensitivity at room temperature, is difficult to be used for detecting flammable and explosive gases, and has poor selectivity.
In order to achieve the above purpose, the technical idea of the invention is as follows: the core of the sensitivity improvement of the gas sensitive device is to increase the reaction degree of the redox reaction in the detection process, the stronger the degree of the redox reaction is, the more the number of the electrons constrained and released in the gas sensitive device is, and the faster the speed of the constraining and releasing process is, so that the resistance change of the gas sensitive device is more obvious, namely the higher the sensitivity of the gas sensitive device is. The traditional semiconductor gas-sensitive device increases the reaction degree of oxidation-reduction reaction by improving the activity of air and gas to be detected, namely the required working temperature is higher, so that the gas-sensitive device can not normally work at room temperature. The application provides a novel gas-sensitive material, namely a gold nanoparticle modified nickel molybdate nano composite material, wherein gold nanoparticles are modified on the surface of a nano spherical nickel molybdate sphere, the particle sizes of the nickel molybdate sphere and the gold nanoparticles are both in a nano magnitude, the surfaces of the nickel molybdate sphere and the gold nanoparticles are connected through chemical bonds, and the gold nanoparticles are uniformly distributed on the surface of the nickel molybdate sphere. Specifically, under the condition of illumination, local surface plasmon resonance is generated on metal nanoparticles on the surface of the bimetallic oxide semiconductor nickel molybdate, a strong electric field is generated on the surface of gold nanoparticles (AuNPs), and the strong electric field generates a large number of hot electrons on the surface of the bimetallic oxide semiconductor nickel molybdate, so that more oxygen molecules in the air are adsorbed on the surface of the bimetallic oxide semiconductor nickel molybdate, more electrons are constrained, more oxygen anions are generated, and the reaction degree in the oxidation process is stronger; when a gas sensitive device based on a gas sensitive material is in a gas to be detected, on one hand, a strong electric field enables more gas molecules to be detected to gather on the surface of the bimetallic oxide semiconductor nickel molybdate, and on the other hand, the strong electric field enables the reduction reaction process of the gas molecules to be detected and oxygen anions generated in the oxidation process to be faster, and releases more electrons into a conduction band of the bimetallic oxide semiconductor nickel molybdate, namely, the released electrons in the reduction process are more and faster, namely, the reaction degree in the oxidation process is stronger; the resistance of the gas sensitive device is changed greatly due to the oxidation reaction and the reduction process, so that when the gas sensitive material is used for the gas sensitive device, the sensitivity of the gas sensitive device is higher. The sensitivity of the gas sensitive device is improved by increasing the activity of air and gas to be detected, namely the sensitivity of the gas sensitive device based on the gas sensitive material does not depend on a high-temperature condition during working, so that the working temperature of the gas sensitive device can be reduced, namely the gas sensitive device based on the gas sensitive material prepared by the method disclosed by the invention can work at room temperature and has higher sensitivity.
The application also provides a preparation method of the gold nanoparticle modified nickel molybdate nanocomposite, which comprises the following steps:
s1, preparing nickel molybdate nanospheres;
first, 0.0363-0.363g Ni (NO) was weighed 3 ) 2 ·6H 2 O and 0.0302-0.302g Na 2 MoO 4 ·2H 2 Dissolving O in 50-500ml deionized water, and adding 0.075-0.75g urea and 0.0277-0.278g NH after completely dissolving 4 And F, continuously stirring until a uniform mixed solution is formed. Then, transferring the mixture to a hydrothermal reaction kettle for hydrothermal reaction, specifically, the hydrothermal reaction temperature is 120-200 ℃, and the hydrothermal reaction time is 2-12h, so that the hydrothermal reaction can be fully performed, and precipitates obtained by the hydrothermal reaction are centrifuged and washed, wherein NH is contained in the precipitates 4 F is a surfactant, so that active sites on the surface of the nickel molybdate can be effectively increased, and urea participates in the reaction to finally generate the nickel molybdate hydrate. And drying the obtained nickel molybdate hydrate at 60 ℃ for 6h in vacuum, and finally calcining for 0.5-2h at the temperature of 350-450 ℃ to finally obtain the powdery nickel molybdate nanospheres.
S2, preparing the AuNPs modified nickel molybdate nano composite material.
With trisodium citrate (Na) 3 C 6 H 5 O 7 ·2H 2 O) reduction of HAuCl 4 The method of (1) directly generating gold nanoparticles on the surface of the nickel molybdate nanospheres, and using PVP (polyvinylpyrrolidone K30) as a buffer. Specifically, HAuCl with the concentration of 0.01mol/L is prepared 4 A solution; weighing 0.0218-0.218g of nickel molybdate nanosphere powder prepared in the step S1, and dissolving the nickel molybdate nanosphere powder in 50-500ml of deionized water; then 0.1-1.0g PVP and 0.5-5.0ml HAuCl with the prepared concentration of 0.01mol/L are taken 4 Adding the aqueous solution into the nickel molybdate mixed solution, continuously stirring on a magnetic stirrer to uniformly mix the solution, and heating the mixed solution to boiling while stirring; then, while stirring, 1-10ml of 1% Na was added to the mixed solution 3 C 6 H 5 O 7 ·2H 2 And continuously boiling the O aqueous solution, naturally cooling to room temperature after the reaction is finished, stirring to fully mix, centrifuging, washing, drying and storing for later use to obtain the powdery AuNPs modified nickel molybdate nano composite material.
Preparation of HAuCl in the present invention 4 The solvent of the solution is one of double distilled water, triple distilled water and high-quality deionized water, and the prepared HAuCl 4 The solution glass container must be absolutely clean, rinsed with acid and deionized water before use, and dried for use. At the same time, HAuCl is prepared 4 The solution cannot be weighed by a metal spoon.
Meanwhile, the process for preparing the AuNPs modified nickel molybdate nano composite material is simple, pollution-free, efficient and stable, and the prepared composite material has high crystallinity. The gas-sensitive device of the gas-sensitive material prepared by the method can work at room temperature, has higher sensitivity and has wide application prospect.
In order to test the gas-sensitive characteristics of the gas-sensitive material prepared by the method, a gas-sensitive testing device is prepared, and meanwhile, gas-sensitive testing is performed on the gas-sensitive performance of the prepared gas-sensitive material by utilizing HCRK-SD101 four-channel gas-sensitive performance testing software. The result shows that the gas sensitive device of the gas sensitive material prepared by the method has higher sensitivity, and the high sensitivity of detection does not depend on the activity of background gas or gas to be detected, so the detection can be carried out at room temperature without high temperature, and the method has important significance for the detection of inflammable and explosive gas.
Compared with the prior art, the invention has the beneficial effects that: the prepared AuNPs modified nickel molybdate nanocomposite is used as a gas sensitive material, and the local surface plasmon resonance effect generated by AuNPs is utilized under the illumination condition, so that the high-sensitivity detection of the gas to be detected at room temperature is realized, the response time is short, and the selectivity is good. In addition, the preparation method is simple, pollution-free, efficient and stable, the synthesized material has high crystallinity, and the gas sensitive device of the gas sensitive material prepared by the method can work at room temperature and has wide application prospect. Therefore, the gas sensitive device of the gas sensitive material prepared by the method has high sensitivity, is suitable for gas detection at room temperature, can be used for detecting flammable and explosive gases, and has good selectivity.
Drawings
FIG. 1 is a schematic diagram of a method for preparing a gold nanoparticle-modified nickel molybdate nanocomposite according to the present invention;
fig. 2 is a diagram of the nickel molybdate nanosphere material obtained in step S1 in the preparation method of the gold nanoparticle-modified nickel molybdate nanocomposite provided by the invention;
fig. 3 is a diagram of an object of the AuNPs-modified nickel molybdate nanocomposite obtained in step S2 in the preparation method of the gold nanoparticle-modified nickel molybdate nanocomposite according to the present invention;
fig. 4 is a diagram of a gas-sensitive test device prepared from the AuNPs-modified nickel molybdate nanocomposite prepared by the method for preparing the gold nanoparticle-modified nickel molybdate nanocomposite provided by the invention.
Fig. 5 is an XRD diffraction spectrum of the nickel molybdate nanosphere material prepared in step S1 of the preparation method of a gold nanoparticle-modified nickel molybdate nanocomposite provided in the present invention;
fig. 6 is an SEM characterization image of the nickel molybdate nanosphere material prepared in step S1 of the method for preparing a gold nanoparticle-modified nickel molybdate nanocomposite according to the present invention;
fig. 7 is an SEM characterization image of the AuNPs-modified nickel molybdate nanocomposite prepared in step S2 of the method for preparing a gold nanoparticle-modified nickel molybdate nanocomposite according to the present invention;
fig. 8 is a response recovery curve of a gas sensitive device prepared from a material prepared by the preparation method of the gold nanoparticle modified nickel molybdate nanocomposite material provided by the invention.
Detailed Description
In order to make the implementation of the present invention clearer, the following detailed description is made with reference to the accompanying drawings.
Example 1:
the application provides a novel gas-sensitive material, namely a gold nanoparticle modified nickel molybdate nano composite material, wherein gold nanoparticles (AuNPs) are modified on the surface of a nano spherical nickel molybdate sphere, the particle sizes of the nickel molybdate sphere and the AuNPs are both in a nanometer magnitude, the surfaces of the nickel molybdate sphere and the AuNPs are connected through chemical bonds, and the AuNPs are uniformly distributed on the surface of the nickel molybdate sphere.
The invention also provides a preparation method of the gold nanoparticle modified nickel molybdate nano composite material, which comprises the following steps:
s1, preparing nickel molybdate nanospheres;
weighing Ni (NO) 3 ) 2 ·6H 2 O and Na 2 MoO 4 ·2H 2 Dissolving O in deionized water, adding urea and NH after complete dissolution 4 F, continuously stirring until a uniform mixed solution is formed, then transferring the mixed solution to a hydrothermal reaction kettle for hydrothermal reaction, centrifuging, washing and vacuum-drying a hydrothermal reaction product, and finally calcining the hydrothermal reaction product in the air to obtain NiMoO 4 Nanospheres.
Specifically, first, 0.0302g of Na was weighed 2 MoO 4 ·2H 2 Dissolving O in 50ml deionized water, and stirring to dissolve completely to obtain Na with concentration of 2.5mmol/L 2 MoO 4 ·2H 2 O solution, Na 2 MoO 4 ·2H 2 The concentration of the O solution is very critical for preparing the nickel molybdate nanospheres with loose and porous surfaces and good crystallinity, and the appearance and crystallinity of the nickel molybdate nanospheres are poor due to the change of the concentration, so that the final gas-sensitive characteristic is influenced; weighing the same amount of Ni (NO) 3 ) 2 ·6H 2 0.0363g of O was added to the above mixed solution, so that nickel ions having the same valence as 2 and molybdate ions were reacted in a ratio of 1:1, and stirring was continued until Ni (NO) was added 3 ) 2 ·6H 2 The O is completely dissolved, and the mixed solution becomes clear; then 0.0277g NH was weighed 4 F (solution concentration 15mmol/L) and 0.075g of urea (solution concentration 25mmol/L) were added together to the mixed solution, and stirring was continued for 1h to add NH 4 F and urea are sufficiently dissolved, wherein NH 4 F is a surfactant, active sites on the surface of the nickel molybdate are increased, preparation is made for modification of AuNPs, the uniformity degree and the distribution density of the distribution of the active sites determine the distribution of the AuNPs, the uniformity and the density of the distribution of the AuNPs determine the gas-sensitive characteristics of the synthesized gas-sensitive material, the better the uniformity of the AuNPs, the stronger the enhancement of the gas-sensitive characteristics of the gas-sensitive material, and particularly, when the concentration is constant, the NH is optimally used 4 The proportion of the F and the urea is 0.37, so that the action strength of the surfactant is constant, the proportion of the surfactant is too small, the action of the surfactant is not obvious, when the proportion of the surfactant is large, the waste of the surfactant is caused on one hand, and on the other hand, the side effect is caused by excessive surfactant, particularly, NH 4 F is a strong acid weak base salt, the pH value of the reaction solution and NH 4 F is closely related in quantity, NH 4 The amount of F is too large, the pH value of the solution is too low, and the main exposed crystal face of the nickel molybdate is greatly influenced, so that the main exposed crystal face is changed from 220 to 110, the surface appearance is not spherical any more, nickel molybdate nanospheres cannot be obtained, and the effect of the surfactant is not obvious.
Then, the obtained mixed solution is put into a hydrothermal reaction kettle for hydrothermal reaction, and precipitates obtained by the hydrothermal reaction are separatedHeart, and deionized water with ethanol 1: 3, washing the mixed solution for several times to remove impurity ions such as sodium ions and nitrate radicals until the pH value of the solution becomes 6.8-7.0, and ending the washing process, wherein specifically, the nickel nitrate is strong acid and weak base salt, the pH value is 4.0-5.0, namely, the mixed solution put into the hydrothermal reaction kettle is weakly acidic, and reacts under an acidic condition to generate nickel molybdate hydrate, and the impurity ions such as sodium ions and nitrate radicals are removed by washing for multiple times with ethanol and deionized water, so that the pH value of the mixed solution becomes 6.8-7.0, namely, the removal of the impurity ions is finished; more specifically, the hydrothermal reaction is carried out at 120-200 ℃ for 2-12h, in this example, at 160 ℃ for 12h, and at such a temperature, the nickel molybdate can nucleate and has a high nucleation rate, good crystallinity and a sufficient hydrothermal reaction process, and more specifically, the surfactant NH 4 F effectively increases the active sites on the surface of the nickel molybdate, prepares for step S2, takes part in the reaction, and dissolves the urea in the deionized water to decompose into NH 3 And CO 2 ，NH 3 Further decomposed to NH 4 + And OH - ，CO 2 Can be hydrolyzed into CO 3 2- And H + And Ni 2+ Susceptible to reaction with OH-to form Ni (OH) χ Precipitating, and reacting with MoO under acidic condition 4 2- Reacting to generate nickel molybdate hydrate; more specifically, the equation for the reaction process is: n is a radical of 2 H 4 CO+H 2 O→NH 3 +CO 2 ， CO 2 +H 2 O→CO 3 2- +2H + ，NH 3 +H 2 O→NH 4 + +OH-， Ni(NO 3 ) 2 +Na 2 MoO 4 →Ni 2+ +MoO 4 2- +NaNO 3 +H 2 O，Ni 2+ +χOH - →Ni(OH) χ ， Ni(OH) χ +MoO 4 2- +2H + →NiMoO 4 ·χH 2 O。
Finally, the generated nickel molybdate hydrate is dried in a vacuum drying oven at 60 ℃ for 6 hours in vacuum to avoid pollution of other impurities in the air to the generated nickel molybdate hydrate, and then the nickel molybdate hydrate is placed in a muffle furnace, specifically, the nickel molybdate hydrate is placed in a crucible in the muffle furnace to be calcined, and the calcined nickel molybdate hydrate reacts with oxygen to finally obtain nickel molybdate nanospheres, more oxygen vacancies can be formed on the surfaces of the nickel molybdate nanospheres in the calcining process to achieve the effect of sensitizing materials, so that the redox reaction process on the gas-sensitive materials in the detection process is more violent, and the sensitivity of the gas-sensitive device based on the gas-sensitive materials prepared by the method is improved; specifically, the nickel molybdate nanosphere is calcined at 350-450 ℃ for 0.5-2h in an air atmosphere, specifically, the calcination temperature is 400 ℃, so that the nickel molybdate hydrate can be completely decomposed into nickel molybdate crystals and water, the water is dried, and the calcination time is 2h, so that the reaction can be fully completed, and the nickel molybdate nanosphere shown in fig. 2 is obtained.
The prepared nickel molybdate is spherical, the diameter is hundreds of nanometers, the surface is a loose and porous structure, and the crystallinity is better. The specific surface area and the porosity of the gas-sensitive material are effectively improved due to the small particle size and the loose porous structure, on one hand, a premise is provided for preparing AuNPs in the step S2, and more AuNPs can be stably attached to the surface of the nickel molybdate nanosphere; on the other hand, the porous loose structure enables oxygen molecules and gas molecules to be detected in the air to rapidly diffuse to reach the interior of the nickel molybdate nanospheres, and the large specific surface area can adsorb more oxygen molecules and gas molecules to be detected, so that the oxidation-reduction reaction speed is accelerated, the response time and recovery time of the gas-sensitive reaction are reduced, and the sensitivity of the gas-sensitive device made of the gas-sensitive material prepared by the method is high.
Na 2 MoO 4 ·2H 2 The concentration of the O solution is 2.5 mmol/L; ni (NO) 3 ) 2 ·6H 2 The amount of O and Na 2 MoO 4 ·2H 2 O is the same; NH in solution 4 The concentration of F is 15 mmol/L; the concentration of urea is 25 mmol/L; NH (NH) 4 The proportion of the amount of F to the amount of urea is 0.37; the hydrothermal reaction temperature is 160 ℃, and the reaction time is 12 hours; the combined action of the parameters ensures that the prepared nickel molybdate nanospheres have the diameter of hundreds of nanometers, loose and porous structures on the surfaces, good crystallinity, different hydrothermal reaction temperatures and times, different drug concentrations and different chemical concentrationsDifferent main crystal face crystals that expose can be generated to the proportion, and then the appearance, surface activity, the nucleation condition of nickel molybdate nanosphere all are different, and the parameter of this application is hundred nanometers to preparing the size, and the surface is loose, porous structure, and the better nickel molybdate nanosphere of degree of crystallinity is essential. Fig. 5 is an XRD diffraction spectrum of the prepared nickel molybdate nanosphere, wherein the upper part is a test result of the nickel molybdate nanosphere material prepared in this embodiment, the lower part is a peak position corresponding to the standard card, and an XRD diffraction peak of the nickel molybdate nanosphere material is completely matched with the standard card, which indicates that the material prepared in step S1 is nickel molybdate. Fig. 6 is an SEM characterization image of the nickel molybdate nanosphere material prepared in step S1, which indicates that the prepared nickel molybdate is indeed nanosphere morphology. That is, the material prepared in step S1 of the present invention is nickel molybdate nanospheres.
S2, preparing the AuNPs modified nickel molybdate nano composite material.
With trisodium citrate (Na) 3 C 6 H 5 O 7 ·2H 2 O) reduction of HAuCl 4 The method of (1) directly generating gold nanoparticles on the surface of the nickel molybdate nanospheres, and using PVP (polyvinylpyrrolidone K30) as a buffer. Specifically, HAuCl 4 Concentration of solution, Na 3 C 6 H 5 O 7 ·2H 2 The concentration of the O solution, the concentration of the nickel molybdate mixed solution and the concentration of PVP, namely the corresponding proportion, are crucial to the modification effects of the generated AuNPs and AuNPs, and the gas-sensitive characteristics of the prepared AuNPs-modified nickel molybdate nanocomposite are greatly different due to slight changes.
First, HAuCl was prepared at a concentration of 0.01mol/L 4 Solution, HAuCl 4 Concentration of the solution and Na 3 C 6 H 5 O 7 ·2H 2 The concentration of the O solution corresponds to that of the O solution, and the proportion of the two dosage can determine the size of the generated AuNPs; 0.0218g of nickel molybdate nanosphere powder prepared in step S1 is weighed and dissolved in 50ml of deionized water, and ultrasonic dispersion is carried out for 15min at the same time, so that NiMoO is obtained 4 Fully dispersing the powder in deionized water to obtain nickel molybdate mixed solution, wherein the concentration of the nickel molybdate mixed solution is 2.0mol/L, and the concentration of the acid nickel nanosphere solution isGreater than 2.0mol/L, the modification effect is not obvious, the concentration of acid nickel nanosphere solution is less than 2.0mol/L, the corresponding AuNPs are more, cause unnecessary cost waste, too much AuNPs can also influence the gas to be measured and the contact of background gas and gas sensitive material simultaneously, make redox reaction weaker, be unfavorable for promoting gas sensitive material's performance.
Then, 0.1g of PVP was taken as a buffer and 0.5ml of HAuCl prepared as described above at a concentration of 0.01mol/L 4 Adding the two into the nickel molybdate mixed solution, continuously stirring for 30min on a magnetic stirrer to uniformly mix the solution, and heating the mixed solution to boiling while stirring; the added PVP is used as a buffering agent, so that the agglomeration of AuNPs can be effectively prevented, the compounding of the AuNPs and the nickel molybdate nanospheres is promoted, the AuNPs are uniformly dispersed on the surfaces of the nickel molybdate nanospheres, local surface plasmon resonance is generated under illumination, a strong electric field is generated on the surfaces of the AuNPs and nearby the AuNPs, the uniform dispersion of the AuNPs ensures that the interaction between the strong electric field and electrons in the nickel molybdate nanospheres and oxygen anions, oxygen molecules and gas molecules to be detected on the surfaces of the nickel molybdate nanospheres is strong, the strength of redox reaction is strong, and the caused resistance change in the gas sensitive material is large, so that the sensitivity of a gas sensitive device of the gas sensitive material prepared based on the method is high. In particular, in HAuCl 4 The quality of PVP and HAuCl under the condition of no change of aqueous solution 4 The volume ratio of the aqueous solution is 1:5, the ratio can effectively prevent the AuNPs from agglomerating, and the excessive PVP content can lead excessive PVP molecules to wrap and attach to HAuCl 4 Surface, hindering it from Na 3 C 6 H 5 O 7 ·2H 2 The AuNPs are uniformly dispersed on the surface of the nickel molybdate nanosphere through the reaction of O, so that the modification effect is good; the agglomeration of AuNPs can lead the AuNPs not to be dispersed enough, on one hand, the surface of part of nickel molybdate nanospheres is not modified by the AuNPs, on the other hand, the specific surface area of the AuNPs is small, and the local surface plasmon effect generated under illumination is not strong enough, so that the generated strong electric field is weaker, the process of redox reaction cannot be effectively enhanced, and finally, the gas-sensitive property of the gas-sensitive material is poorer; excess PVP hinders the AuNPs systemThe prepared oxidation-reduction reaction generates large-sized AuNPs, and the amount of the AuNPs is reduced, so that the modification effect on the nickel molybdate material is not ideal, and the gas-sensitive performance is influenced finally.
Then, 1ml of 1% Na was added to the boiling mixed solution while stirring 3 C 6 H 5 O 7 ·2H 2 Aqueous solution of O, Na 3 C 6 H 5 O 7 ·2H 2 The concentration of the O aqueous solution is 1%, which is the optimal concentration obtained by multiple tests and is also combined with HAuCl 4 The concentration of the solution is closely related, Na 3 C 6 H 5 O 7 ·2H 2 O and HAuCl 4 The ratio of (A) to (B) needs to be strictly controlled, otherwise, the prepared AuNPs have larger size difference, so that the performance of the prepared gas-sensitive material is unstable; boiling for 15min, and light green HAuCl 4 Mixed with nickel molybdate in Na 3 C 6 H 5 O 7 ·2H 2 The color of the solution of AuNPs is closely related to the size of the solution, the color is lighter when the size is smaller, the color is darker when the size is larger, and when the reaction occurs, Na which just begins to participate in the reaction 3 C 6 H 5 O 7 ·2H 2 Less O, larger size of AuNPs and black color, and Na participating in the reaction as the reaction proceeds 3 C 6 H 5 O 7 ·2H 2 More O, smaller size of AuNPs, gradually lighter color, stable orange-red color, and NiMoO 4 The solution was pale green, so the mixture was dark green, and therefore, the dark green color produced was indicative of the small size of AuNPs and NiMoO 4 The successful preparation of the mixed solution of (4); na (Na) 3 C 6 H 5 O 7 ·2H 2 O can react with HAuCl 4 Reducing to AuNPs, the size of the AuNPs obtained in the invention is 10nm-150nm, preferably, the size of the AuNPs is 10nm-20nm, because the AuNPs are too large and NiMoO 4 Has poor compounding effect, NiMoO 4 The AuNPs on the surface are less, and the plasma shock is generatedThe meta effect is weak, and the enhancement effect is poor; when the size of AuNPs is too small, the surface plasmon effect of a single AuNPs is weak, the electric field intensity of the aggregation is weak, so that the enhancement of the redox process in the sensing process is not obvious, and the sensitivity enhancement effect of the gas sensitive device is not obvious; in particular, the size and Na of AuNPs prepared 3 C 6 H 5 O 7 ·2H 2 O and HAuCl 4 The proportion of the amount is closely related, more particularly, Na 3 C 6 H 5 O 7 ·2H 2 The higher the proportion of O, the smaller the size of AuNPs prepared, more specifically, HAuCl which is required for preparing AuNPs with a size of 10-20nm 4 And Na 3 C 6 H 5 O 7 ·2H 2 The volume ratio of the used amount of O is 1: 2.
And finally, continuously heating, boiling the mixed solution for 30min to fully perform the reduction reaction, stopping heating after the reaction is completed, cooling the mixed solution to room temperature, continuously stirring for 1h to fully attach the generated AuNPs to the nickel molybdate nanospheres, and centrifuging, washing and drying after the reaction is finished to obtain a final product, wherein a picture shown in figure 3 is a real picture of the obtained AuNPs-modified nickel molybdate nanocomposite. Specifically, ethanol and deionized water 1: 3, mixing and washing for a plurality of times, pouring off the centrifuged solution each time, and adding the mixture again into the reactor with the weight ratio of 1: 3, and deionized water until the PH of the solution becomes 6.8-7, and the washing process is complete. And then drying for 6h in vacuum at 60 ℃ to avoid the influence of other impurities in the air on the generated material, and finally obtaining the AuNPs modified nickel molybdate nano composite material, wherein a material object diagram is shown in FIG. 3. Fig. 7 is an SEM characterization image of the prepared AuNPs-modified nickel molybdate nanocomposite, in which the surface of the spherical nickel molybdate nanoparticles is more porous and porous after the AuNPs modification, indicating that step S2 indeed prepared the AuNPs-modified nickel molybdate nanocomposite.
Furthermore, preparation of HAuCl 4 The solvent of the solution is double distilled water or triple distilled water or high-quality deionized water, the impurity ions in the water have great influence on the synthesis process of AuNPs, and the double distilled water or the triple distilled water or the high-quality deionized water can be adoptedThe influence of impurity ions such as hydrogen ions and hydroxyl ions in the solvent on AuNPs can be avoided, and the influence of the solvent on the synthesis result can be effectively reduced. Due to high requirement on cleanliness, dust particles, oil stain and other particles are in harml 4 The solution has large influence, and the prepared HAuCl 4 The solution glass containers must be absolutely clean, rinsed with acid and rinsed with deionized water before use, and dried for use. HAuCl 4 Has strong corrosion effect on metals, so HAuCl is prepared in 4 The solution cannot be weighed with a metal spoon.
In order to test the gas-sensitive characteristics of the AuNPs modified nickel molybdate nanocomposite prepared by the method, the AuNPs modified nickel molybdate nanocomposite obtained in the step S2 is fully ground in a quartz mortar, a certain amount of terpineol is added to be mixed and continuously ground until a uniform paste mixture is formed and has certain fluidity, and then the paste mixture is uniformly coated on a gas-sensitive testing device by using screen printing, so that the terpineol in the mixture volatilizes at high temperature, and the left gas-sensitive material can form a dense, smooth and uniform-thickness gas-sensitive material film, and the resistance measurement of the gas-sensitive material film is more accurate, and therefore, the accuracy of the gas-sensitive device is higher. Then, the gas sensitive material is placed on a heating plate, after solidification, annealing treatment is carried out, the annealing temperature is 300-400 ℃, the annealing temperature is preferably 400 ℃, the annealing time is 1-4h, the annealing time is preferably 4h, oxygen vacancies can be generated on the surface of the gas sensitive material in the air, so that the adsorption process and the desorption process of the surface of the gas sensitive material are more sufficient, namely the oxidation process and the reduction process are faster, the response recovery speed is improved, the oxygen vacancies can be introduced while the hydrate is evaporated at 400 ℃, and the annealing time is 4h, so that more oxygen vacancies can be formed. And (3) after annealing, aging for 24h, and performing gas-sensitive test to prepare a gas-sensitive test element object diagram, which is shown in FIG. 4. More specifically, the substrate of the gas sensitive test device is alumina (Al) 2 O 3 ) The material is characterized in that a platinum (Pt) electrode covers the substrate and is used for detecting the resistance change of the gas sensitive testing device.
This application utilizes HCRK-SD101 four-channel gasAnd the sensitivity performance testing software is used for carrying out gas sensitivity test on the gas sensitivity performance of the prepared gas sensitive material. The testing process is carried out at room temperature (25 ℃), a light source is arranged right above the gas-sensitive material, light emitted by the light source irradiates on the gas-sensitive material, and specifically, the light source can be a visible light source or an ultraviolet light source. During testing, the background gas is clean air, the gas to be tested is ethanol gas, and the concentration of the gas to be tested is controlled by controlling the flow ratio of the background gas to the gas to be tested. The results of the response recovery curves of the tests are shown in the curve represented by the solid squares in FIG. 8, the sensitivity of the gas sensitive test device to 100ppm ethanol at room temperature is 10, the response time is 30s, the recovery time is 100s, and the sensitivity is higher than Kuchi, PS and the like under the condition of being entitled "A novel RoomTemperature enhanced reactor based on PbS: SnS 2 The results of the sensitivity of ethanol gas at room temperature disclosed in the article of nanocomposite with enhanced ethanol sensing properties "were 45.6% to 100%, specifically, 45.6% means that the sensitivity was 1.456, and 100% means that the sensitivity was 2, both of which are smaller than 10 of the present example. Specifically, AuNPs on the surface of the gas-sensitive material generate local surface plasmon resonance under the action of illumination, a strong electric field is generated on the surface of the AuNPs, and the strong electric field generates a large number of thermal electrons on the surface of nickel molybdate, so that more oxygen molecules in the air are adsorbed on the surface of nickel molybdate, the oxidation reaction strength is stronger, more electrons in the nickel molybdate can be captured, the detection resistance is increased, and more oxygen anions are generated; in ethanol, under the action of a strong electric field, gas molecules of the ethanol are adsorbed on the surfaces of the nickel molybdate nanospheres more, so that the gas molecules of the ethanol are subjected to reduction reaction with oxygen anions generated in the oxidation process, meanwhile, the strong electric field enables the strength of the reduction reaction to be stronger, more electrons are rapidly released in the reduction process, and the detected resistance is rapidly reduced; namely, under the same concentration of gas to be detected, the resistance of the gas sensitive device of the gas sensitive material prepared by the method is changed more rapidly, which means that the sensitivity is higher, so that the gas sensitive device can realize high-sensitivity monitoring at room temperature, and the dependence of the gas sensitive device on a high-temperature environment is greatly reduced.
It should be noted that, in the following description,the test process takes ethanol as an example, and does not represent that the gas-sensitive material prepared by the method can only be used for detecting the ethanol, and the gas-sensitive material prepared by the method is suitable for detecting reductive gases such as ethanol, methanol, formaldehyde and n-butyl alcohol. The gas-sensitive material prepared by the method has almost no response to carbon monoxide reducing gas, so that the gas-sensitive material prepared by the method has good selectivity; specifically, compared with the traditional single metal oxide, the nickel molybdate prepared by the invention is a multi-transition metal oxide, and simultaneously forms a heterojunction with AuNPs modified on the multi-transition metal oxide, since NiMoO4 is a catalyst with excellent performance, and since Mo and Ni in the NiMoO4 are synergistic catalytic effects, the catalyst is considered to be a good catalyst for promoting partial oxidation of hydrocarbon and oxidative dehydrogenation of alkane, the catalyst can selectively adsorb gas to be detected, and more specifically, the catalyst is named as NiMoO 4 Selective Oxidation Catalysts Containing Excess MoO 3 for the Conversion of C 4 Hydrocarbon to Maleic Anhydride. The selective adsorption of the gas to be detected of the gas sensitive material is improved, so that the gas selectivity of a gas sensitive device based on the gas sensitive material is also improved.
Example 2:
this embodiment is different from embodiment 1 in that:
in step S1, 0.151g of Na was weighed 2 MoO 4 ·2H 2 O was dissolved in 250ml of deionized water, and Ni (NO) was weighed out accordingly 3 ) 2 ·6H 2 The mass of O is 0.182g, after stirring for 20min, 0.139g NH is weighed 4 F was added to the mixed solution together with 0.375g of urea to dissolve it sufficiently. The temperature of the hydrothermal reaction is 120 ℃, and the time is 10 hours; the calcination temperature is 450 ℃ and the calcination time is 1 h. The remainder was in accordance with example 1.
In step S2, 0.109g of nickel molybdate nanosphere powder prepared in step S1 is weighed and dissolved in 250ml of deionized water, and after ultrasonic dispersion, 0.5g of PVP and 2.5ml of HAuCl prepared with the concentration of 0.01mol/L are taken 4 Adding the two into the mixed solution, continuously stirring with a magnetic stirrer to uniformly mix the solution, and stirring while dissolving the mixtureHeating the solution to boiling, adding 5ml of 1% Na while stirring 3 C 6 H 5 O 7 ·2H 2 And (4) O aqueous solution. The remainder was in accordance with example 1.
The annealing temperature is 350 ℃ and the annealing time is 1h when the gas sensitive test device is prepared. The gas-sensitive test is carried out on the prepared gas-sensitive test device by using HCRK-SD101 four-channel gas-sensitive performance test software, the result of the response recovery curve of the test is shown as the curve represented by the solid circle in figure 8, the sensitivity of the gas-sensitive test device to 100ppm ethanol at room temperature is 10.2, the response time is 25s, and the recovery time is 90 s.
Example 3:
this embodiment is different from embodiment 1 in that:
in step S1, 0.302g of Na is weighed 2 MoO 4 ·2H 2 O was dissolved in 500ml of deionized water, and Ni (NO) was weighed out correspondingly 3 ) 2 ·6H 2 The mass of O is 0.363g, stirring is carried out until the O is mixed evenly, and 0.278g NH is weighed 4 F and 0.75g of urea were added together to the mixed solution to be sufficiently dissolved. The temperature of the hydrothermal reaction is 200 ℃ and the time is 2 h; the calcination temperature was 350 ℃ and the calcination time was 0.5 h. The remainder was in accordance with example 1.
In step S2, 0.218g of the nickel molybdate nanosphere powder prepared in step S1 is weighed and dissolved in 500ml of deionized water, and after ultrasonic dispersion, 1.0g of PVP and 5ml of HAuCl with the prepared concentration of 0.01mol/L are taken 4 Adding the two into the mixed solution, continuously stirring with a magnetic stirrer to uniformly mix the solution, heating the mixed solution to boiling while stirring, and adding 10ml of 1% Na into the mixed solution while stirring 3 C 6 H 5 O 7 ·2H 2 And (4) O aqueous solution. The remainder was in accordance with example 1.
The annealing temperature is 300 ℃ and the annealing time is 2h when the gas sensitive test device is prepared. The gas-sensitive test is carried out on the prepared gas-sensitive test device by using HCRK-SD101 four-channel gas-sensitive performance test software, the result of the response recovery curve of the test is shown as the curve represented by the solid triangle in figure 8, the sensitivity of the gas-sensitive test device to 100ppm ethanol at room temperature is 9.5, the response time is 35s, and the recovery time is 120 s.
In the three embodiments of the invention, the concentration of each solution is the same, specifically, the volume of each solution is different, and the test results show that the gas-sensitive materials prepared by the three embodiments have good gas-sensitive characteristics, and the sensitivity of the corresponding gas-sensitive test device is higher than that of an A novel porous enhanced gas sensor based on PbS 2 The nanocomposite with enhanced ethanol sensing properties "article discloses the results of a sensitivity of ethanol gas at room temperature of 1.456 to 2, with a response time of not longer than 35s and a recovery time of not longer than 120 s. The method for preparing the gas-sensitive material is stable, efficient and good in repeatability.
Generally, the activity of the gas to be measured and the background gas is higher with the increase of the temperature, so that the strength of the redox reaction is stronger, namely, the sensitivity of the gas sensitive device is higher with the higher temperature. Because of different ideas for improving the sensitivity, the gas sensitive device based on the gas sensitive material prepared by the method has higher sensitivity at room temperature and higher sensitivity at high temperature, and the gas sensitive material prepared by the method can normally work at 25-160 ℃ and has higher sensitivity. In particular, the kit can be used for detecting flammable and explosive gases at room temperature.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The nickel molybdate nanocomposite modified by the gold nanoparticles is characterized by comprising a nickel molybdate material and the gold nanoparticles, wherein the nickel molybdate material is spherical, the particle size of the nickel molybdate material is in a nanometer level, the gold nanoparticles are spherical, the particle size of the gold nanoparticles is in a nanometer level, the gold nanoparticles are distributed on the surface of the nickel molybdate material, and the gold nanoparticles and the nickel molybdate material are fixedly connected through chemical bonds.
2. The method for preparing gold nanoparticle modified nickel molybdate nanocomposite according to claim 1, comprising the steps of:
s1, preparing nickel molybdate nanospheres;
s2, preparing the gold nanoparticle modified nickel molybdate nano composite material.
3. The method for preparing gold nanoparticle-modified nickel molybdate nanocomposite material according to claim 2, wherein the step S1 comprises weighing Na 2 MoO 4 ·2H 2 Dissolving O in deionized water, stirring, adding Ni (NO) after dissolving completely 3 ) 2 ·6H 2 O, after complete dissolution again, urea and NH are added simultaneously 4 F, stirring again, and fully dissolving; and transferring the obtained mixed solution into a hydrothermal reaction kettle for hydrothermal reaction, and centrifuging, washing, vacuum drying and calcining the product of the hydrothermal reaction to obtain the powdery nickel molybdate nanospheres.
4. The method of claim 3, wherein the Na is selected from the group consisting of sodium, potassium, magnesium, aluminum, magnesium, aluminum, copper, aluminum, and combinations thereof 2 MoO 4 ·2H 2 O and said Ni (NO) 3 ) 2 ·6H 2 The molar mass of O is the same.
5. The method for preparing gold nanoparticle-modified nickel molybdate nanocomposite material according to claim 4, wherein the temperature of the hydrothermal reaction is 120-200 ℃, and the time of the hydrothermal reaction is 2-12 h.
6. The method for preparing gold nanoparticle-modified nickel molybdate nanocomposite material according to claim 5, wherein the calcining temperature is 350-450 ℃, and the vacuum drying time is 0.5-2 h.
7. The method of preparing gold nanoparticle-modified nickel molybdate nanocomposite material as claimed in claim 2, wherein the step S2 includes formulating HAuCl 4 Dissolving the nickel molybdate nanospheres prepared in the step S1 in deionized water to obtain a nickel molybdate mixed solution, and then taking polyvinylpyrrolidone K30 and the HAuCl 4 Adding the solution into the nickel molybdate mixed solution to obtain a mixed solution, continuously stirring, heating the mixed solution to boiling while stirring, and adding Na into the mixed solution while stirring 3 C 6 H 5 O 7 ·2H 2 And continuously boiling the O aqueous solution, naturally cooling to room temperature after the reduction reaction is finished, and centrifuging, washing and vacuum drying to obtain the gold nanoparticle modified nickel molybdate nano composite material.
8. The method of claim 7, wherein the HAuCl is a HAuCl-modified nickel molybdate nanocomposite 4 The concentration of the solution was 0.01 mol/L.
9. The method of claim 8, wherein the HAuCl is a HAuCl-modified nickel molybdate nanocomposite 4 The container of the solution is cleaned with acid and rinsed clean with deionized water and dried for use.
10. The use of the gold nanoparticle-modified nickel molybdate nanocomposite material as claimed in claim 1, wherein the composite material is applicable to detection of reducing gases and gas-sensitive devices.
Priority Applications (1)
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