CN110227474B - LaCoO with oxygen vacancy3Preparation method and application of nano material - Google Patents
LaCoO with oxygen vacancy3Preparation method and application of nano material Download PDFInfo
- Publication number
- CN110227474B CN110227474B CN201910599150.1A CN201910599150A CN110227474B CN 110227474 B CN110227474 B CN 110227474B CN 201910599150 A CN201910599150 A CN 201910599150A CN 110227474 B CN110227474 B CN 110227474B
- Authority
- CN
- China
- Prior art keywords
- lacoo
- nano material
- nano
- oxygen vacancy
- ammonia
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 70
- 239000001301 oxygen Substances 0.000 title claims abstract description 70
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 70
- 239000002086 nanomaterial Substances 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 27
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 83
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 65
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 42
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 40
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 30
- 229910002254 LaCoO3 Inorganic materials 0.000 claims abstract description 27
- 229910052786 argon Inorganic materials 0.000 claims abstract description 20
- 238000005530 etching Methods 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 12
- 230000002194 synthesizing effect Effects 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 23
- YASYEJJMZJALEJ-UHFFFAOYSA-N Citric acid monohydrate Chemical compound O.OC(=O)CC(O)(C(O)=O)CC(O)=O YASYEJJMZJALEJ-UHFFFAOYSA-N 0.000 claims description 14
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 12
- 239000004202 carbamide Substances 0.000 claims description 12
- 238000002360 preparation method Methods 0.000 claims description 12
- 229960002303 citric acid monohydrate Drugs 0.000 claims description 11
- GJKFIJKSBFYMQK-UHFFFAOYSA-N lanthanum(3+);trinitrate;hexahydrate Chemical group O.O.O.O.O.O.[La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O GJKFIJKSBFYMQK-UHFFFAOYSA-N 0.000 claims description 11
- 239000000243 solution Substances 0.000 claims description 10
- 238000001354 calcination Methods 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 7
- 229920000557 Nafion® Polymers 0.000 claims description 6
- 229910017052 cobalt Inorganic materials 0.000 claims description 6
- 239000010941 cobalt Substances 0.000 claims description 6
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 6
- 229910052746 lanthanum Inorganic materials 0.000 claims description 6
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- RJNPRNCPYHCHHV-UHFFFAOYSA-N cobalt(2+) dinitrate tetrahydrate Chemical group O.O.O.O.[Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O RJNPRNCPYHCHHV-UHFFFAOYSA-N 0.000 claims description 5
- 229910002804 graphite Inorganic materials 0.000 claims description 5
- 239000010439 graphite Substances 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- 238000001020 plasma etching Methods 0.000 claims description 5
- 238000003487 electrochemical reaction Methods 0.000 claims description 4
- 239000002904 solvent Substances 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 abstract description 24
- 230000003197 catalytic effect Effects 0.000 abstract description 6
- 229910044991 metal oxide Inorganic materials 0.000 abstract 1
- 150000004706 metal oxides Chemical class 0.000 abstract 1
- 238000004519 manufacturing process Methods 0.000 description 22
- 239000011943 nanocatalyst Substances 0.000 description 22
- 239000003054 catalyst Substances 0.000 description 19
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 14
- 239000001257 hydrogen Substances 0.000 description 14
- 229910052739 hydrogen Inorganic materials 0.000 description 14
- 238000012360 testing method Methods 0.000 description 11
- 238000006722 reduction reaction Methods 0.000 description 8
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- ZBYYWKJVSFHYJL-UHFFFAOYSA-L cobalt(2+);diacetate;tetrahydrate Chemical compound O.O.O.O.[Co+2].CC([O-])=O.CC([O-])=O ZBYYWKJVSFHYJL-UHFFFAOYSA-L 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- 239000010931 gold Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 238000006555 catalytic reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000010411 electrocatalyst Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000002135 nanosheet Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 3
- 239000011787 zinc oxide Substances 0.000 description 3
- VRZJGENLTNRAIG-UHFFFAOYSA-N 4-[4-(dimethylamino)phenyl]iminonaphthalen-1-one Chemical compound C1=CC(N(C)C)=CC=C1N=C1C2=CC=CC=C2C(=O)C=C1 VRZJGENLTNRAIG-UHFFFAOYSA-N 0.000 description 2
- 229910021607 Silver chloride Inorganic materials 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- AAMATCKFMHVIDO-UHFFFAOYSA-N azane;1h-pyrrole Chemical compound N.C=1C=CNC=1 AAMATCKFMHVIDO-UHFFFAOYSA-N 0.000 description 2
- DLGYNVMUCSTYDQ-UHFFFAOYSA-N azane;pyridine Chemical compound N.C1=CC=NC=C1 DLGYNVMUCSTYDQ-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 238000005984 hydrogenation reaction Methods 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 2
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 229910019854 Ru—N Inorganic materials 0.000 description 1
- 238000012271 agricultural production Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000002159 nanocrystal Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen(.) Chemical compound [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 1
- 229910052939 potassium sulfate Inorganic materials 0.000 description 1
- 235000011151 potassium sulphates Nutrition 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000027756 respiratory electron transport chain Effects 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000009210 therapy by ultrasound Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/83—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
-
- B01J35/33—
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
Abstract
The invention provides a surface oxygen vacancyLaCoO of a site3A method of preparing a nanomaterial comprising: mixing LaCoO3Etching the nano material in argon plasma to obtain LaCoO with surface oxygen vacancy3And (3) nano materials. The application also provides the LaCoO with the surface oxygen vacancy3The application of the nano material in the reaction of synthesizing ammonia by electrochemically reducing nitrogen. The application improves metal oxide LaCoO by introducing oxygen vacancy3The performance of the nano material enables the obtained LaCoO with oxygen vacancy3The nano material has high catalytic activity, catalytic stability and selectivity.
Description
Technical Field
The invention relates to the technical field of catalysts, in particular to LaCoO with oxygen vacancies3A preparation method and application of the nano material.
Background
Ammonia is a very important chemical raw material and plays a very important role in industrial and agricultural production. At present, the industrial synthesis of ammonia by the Haber method requires high-temperature and high-pressure conditions (150-350 atm, 350-550 ℃), and the harsh conditions need to consume 1-2% of energy supply all over the world every year. In addition, the traditional haber method for synthesizing ammonia needs hydrogen as one of raw materials, and the traditional hydrogen production process can emit a large amount of CO2. Therefore, it is important to search for a catalytic reaction for synthesizing ammonia under mild conditions.
The electrochemical reduction of nitrogen to synthesize ammonia can be carried out at normal temperature and normal pressure, and water can be selected as a hydrogen source, thereby attracting wide attention of scientists. However, since nitrogen molecules are very stable and difficult to activate, the electrocatalyst reported so far has a low ammonia production rate in the electrochemical reduction reaction of nitrogen, and is difficult to meet industrial requirements. Therefore, it is a very challenging task to develop an electrocatalyst capable of efficiently electrochemically reducing nitrogen to ammonia. The current literature reports that the catalysts for electrochemical synthesis of ammonia are mainly:
1) the gold nanorod catalyst with the high-index crystal face can reduce the reaction activation energy and can reduce the reaction speed-determining step (N)2To NNH), the reaction follows an alternative (two-terminal hydrogenation) pathAmmonia production rate of 1.648 microgram/square centimeter/hour, Faraday efficiency of 4.0%;
2)Au/TiO2au nanocrystals are loaded on TiO2, and Au is positively charged due to formation of Au-O-Ti bonds, so that N is easily adsorbed2Formation of chemisorbed Au-N2Bond, promoting activation of N2Ammonia production rate of 21.4. mu.g/mgCatalyst and process for preparing samePer hour, faradaic efficiency 8.11%;
3) gold nanoparticles (Au-NCM) loaded on the nitrogen-doped porous carbon film, electron transfer between Au and NCM enables the surface of NCM to be positively charged, so that strong adsorption can be generated on nitrogen, the nitrogen reduction performance is promoted, the ammonia production rate is 0.36 g/square meter/hour, and the Faraday efficiency is 22%;
4) the ruthenium monatomic catalyst (Ru single atom/N-C) loaded on nitrogen-doped carbon, and the Ru-N unsaturated coordination environment can enhance the adsorption of nitrogen and reduce the reaction speed-determining step (N)2NNH) to improve the performance of electrochemical reduction of nitrogen, and theoretical calculation shows that the reaction follows a distal (terminal hydrogenation) path and the ammonia production rate is 120.9 micrograms/milligramCatalyst and process for preparing sameIn hours, the Faraday efficiency was 29.6%;
5) the nitrogen-doped porous carbon (NPC) has a porous structure which is very favorable for capturing nitrogen and stabilizing intermediates of nitrogen reduction reaction, the contents of pyridine nitrogen and pyrrole nitrogen in the NPC catalyst are very high, the pyridine nitrogen and the pyrrole nitrogen can be used as active center sites of the nitrogen reduction reaction, and the NPC catalyst has very high overpotential for competitive reaction (hydrogen production reaction), so that nitrogen electroreduction can be promoted, and the ammonia production rate is 1.4 mmol/gCatalyst and process for preparing samePer hour, the current efficiency was 1.42%.
Most of the reported catalysts have low ammonia production rate and high performance of individual catalysts, but they use different test conditions and evaluation methods, such as using different electrolytes (for example, a high-concentration potassium ion solution as an electrolyte can inhibit hydrogen production reaction), or making evaluation indexes of the catalysts not unique due to different geometric areas of the electrocatalysts and other factors. Therefore, research on a method for synthesizing ammonia by electrochemically reducing nitrogen is necessary.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a LaCoO with oxygen vacancy3Preparation method of nano material, LaCoO with oxygen vacancy3The nano material has higher selectivity and activity in the reaction of synthesizing ammonia by electrochemically reducing nitrogen, and has better catalytic stability.
In view of the above, the present application provides a LaCoO having surface oxygen vacancies3A method of preparing a nanomaterial comprising:
mixing LaCoO3Etching the nano material in argon plasma to obtain LaCoO with surface oxygen vacancy3And (3) nano materials.
Preferably, the power of the argon plasma etching power supply is 180-250W.
Preferably, the argon pressure of the argon plasma is 8-15 torr, and the etching time is 20 min-1 h.
Preferably, the LaCoO with surface oxygen vacancy3The average size of the nano material is 60 nm-100 nm.
Preferably, the LaCoO3The preparation method of the nano material comprises the following steps:
mixing a lanthanum source, a cobalt source, urea, citric acid monohydrate, water and concentrated nitric acid to obtain gel;
heating the gel, drying and finally calcining to obtain LaCoO3And (3) nano materials.
Preferably, the lanthanum source is lanthanum nitrate hexahydrate, the cobalt source is cobalt nitrate tetrahydrate, the concentrations of the lanthanum nitrate hexahydrate and the cobalt nitrate tetrahydrate are both 0.1-0.2 mol/L, and the concentrations of the urea and the citric acid monohydrate are both 0.2-0.8 mol/L.
Preferably, the heating temperature is 80-100 ℃, the drying temperature is 150-200 ℃, and the calcining temperature is 550-650 ℃.
The application also provides a method for synthesizing ammonia by electrochemically reducing nitrogen, which comprises the following steps:
activated carbon, Nafion solution and LaCoO with oxygen vacancy prepared by the preparation method in the scheme3Dispersing the nano material in a solvent to obtain a mixed solution;
and dropping the mixed solution on an electrode to be used as a working electrode, taking a graphite rod as a counter electrode, introducing nitrogen, and then carrying out electrochemical reaction in an H-shaped electrolytic cell to obtain ammonia.
Preferably, the activated carbon and the LaCoO with oxygen vacancy3The mass ratio of the nano material is 4: 1.
The application provides a LaCoO with oxygen vacancy3A process for preparing nano-class material in LaCoO3The nano material introduces oxygen vacancy through etching, and the introduction of the oxygen vacancy can increase LaCoO3The charge density of the valence band edge of the nano material and the abundant local electrons around the oxygen vacancy are more easily transferred to the reverse bond orbit of the nitrogen molecule, and meanwhile, the introduction of the oxygen vacancy can enhance the adsorption of the nitrogen molecule and reduce the reaction energy barrier of the speed-determining step, so that the activity and the selectivity of the nitrogen electrochemical reduction reaction can be promoted, and simultaneously, LaCoO3The stability of the nano material is self-stable, so that the LaCoO with oxygen vacancy3The nano material has better catalytic stability.
Drawings
FIG. 1 is a LaCoO having surface oxygen vacancies according to example 1 of the present invention3Scanning electron microscope pictures of the nanomaterials;
FIG. 2 shows LaCoO having surface oxygen vacancies according to example 1 of the present invention3Scanning electron microscope pictures of the nanomaterials;
FIG. 3 is a LaCoO having surface oxygen vacancies according to example 1 of the present invention3High resolution transmission electron microscope pictures of nanomaterials;
FIG. 4 shows LaCoO having surface oxygen vacancies according to example 1 of the present invention3Nano material and original LaCoO3An X-ray diffraction pattern of the nanomaterial;
FIG. 5 shows LaCoO having surface oxygen vacancies according to example 1 of the present invention3Nano material and original LaCoO3X-ray of nanomaterialsA line photoelectron energy spectrogram;
FIG. 6 shows LaCoO having surface oxygen vacancies according to example 2 of the present invention3Nano material and original LaCoO3The effective current density curve of the nano material under different overpotentials;
FIG. 7 shows LaCoO having surface oxygen vacancies according to example 2 of the present invention3Nano material and original LaCoO3The Faraday efficiency of the nano material for producing ammonia under different overpotentials;
FIG. 8 shows LaCoO having surface oxygen vacancies according to example 2 of the present invention3Nano material and original LaCoO3The ammonia production rate of the nano material under different overpotentials;
FIG. 9 shows LaCoO having surface oxygen vacancies according to example 3 of the present invention3The ammonia generating rate of the nano material is circularly catalyzed for ten times under the overpotential of-0.7V relative to a standard hydrogen electrode.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
In view of the problem of low ammonia production rate in the prior art of electrochemically reducing nitrogen to prepare ammonia, the application provides LaCoO with oxygen vacancies3A preparation method of nano material and also provides the LaCoO with the oxygen vacancy3The application of the nano material in preparing ammonia by electrochemically reducing nitrogen has been proved by experimental results that LaCoO with oxygen vacancy3The nano material has higher selectivity, activity and catalytic stability in the synthesis of ammonia by electrochemical reduction of nitrogen, and has lower cost.
Specifically, the embodiment of the invention discloses a LaCoO with oxygen vacancy3A method of preparing a nanomaterial comprising:
mixing LaCoO3Etching the nano material in argon plasma to obtain LaCoO with surface oxygen vacancy3And (3) nano materials.
The method has surface oxygen vacancyOf LaCoO3In the process of the nano material, the LaCoO is realized by adopting an etching mode3The surface of the nanomaterial has oxygen vacancies. LaCoO as described in the present application3Preparation of the nanomaterials prepared according to methods well known to those skilled in the art, exemplified by the LaCoO3The preparation method of the nano material comprises the following steps:
mixing a lanthanum source, a cobalt source, urea, citric acid monohydrate, water and concentrated nitric acid to obtain gel;
heating the gel, drying and finally calcining to obtain LaCoO3And (3) nano materials.
In the above LaCoO3In the preparation process of the nano material, the lanthanum source is lanthanum nitrate hexahydrate, the cobalt source is cobalt nitrate tetrahydrate, more specifically, the concentrations of the lanthanum nitrate hexahydrate and the cobalt acetate tetrahydrate are both 0.1-0.2 mol/L, and the concentrations of the urea and the citric acid monohydrate are both 0.2-0.8 mol/L; in a specific embodiment, the concentrations of the lanthanum nitrate hexahydrate and the cobalt acetate tetrahydrate are both 0.125 mol/l, and the concentrations of the urea and the citric acid monohydrate are both 0.5 mol/l; the urea is used for adjusting the pH value of the solution. The heating temperature is 80-100 ℃, the drying temperature is 150-200 ℃, the calcination is carried out in an oxygen atmosphere, the calcination temperature is 550-600 ℃, and the calcination time is 4-6 h. More specifically, the LaCoO3The preparation method of the nano material comprises the following steps:
dissolving lanthanum nitrate hexahydrate, cobalt acetate tetrahydrate, urea and citric acid monohydrate in 30mL of water, wherein the concentrations of the lanthanum nitrate hexahydrate and the cobalt acetate tetrahydrate are both 0.125 mol/L, and the concentrations of the urea and the citric acid monohydrate are both 0.5 mol/L; adding 3 ml of concentrated nitric acid, uniformly mixing, heating to 80 ℃, and magnetically stirring until gel is generated; then drying at 170 ℃ for 12h, calcining the obtained sample at 600 ℃ for 6h under oxygen to obtain LaCoO3And (3) nano materials.
In the above preparation of LaCoO having oxygen vacancies3In the nano material, the etching is carried out in argon plasma, and the specific technical means of the plasma etching is according to the fieldThe method known to the skilled worker is carried out without particular restrictions here.
In a specific embodiment, the power of the argon plasma etching power supply is 180-250W; in a specific embodiment, the power of the argon plasma etching power supply is 200 watts. The argon pressure of the argon plasma is 8-15 torr, and in a specific embodiment, the argon pressure of the argon plasma is 10 torr. The etching time is 20min to 1h, and in a specific embodiment, the etching time is 30 min.
The application also provides a method for synthesizing ammonia by electrochemically reducing nitrogen, namely the prepared LaCoO with oxygen vacancies is applied3The process for synthesizing ammonia by electrochemically reducing nitrogen with nano materials specifically comprises the following steps:
mixing activated carbon, Nafion solution and LaCoO with oxygen vacancy3Dispersing the nano material in a solvent to obtain a mixed solution;
and dropping the mixed solution on an electrode to be used as a working electrode, taking a graphite rod as a counter electrode, introducing nitrogen, and then carrying out electrochemical reaction in an electrolytic cell to obtain ammonia.
In the process of synthesizing ammonia by electrochemically reducing nitrogen, firstly, a mixed solution of the working electrode, namely active carbon, Nafion solution and LaCoO with oxygen vacancy is prepared3The nanomaterial is dispersed in a solvent, which in this application is ethanol; to make LaCoO with oxygen vacancy3The nano material is uniformly distributed on an active carbon carrier, and the active carbon and the LaCoO with the oxygen vacancy3The mass ratio of the nano material is 4: 1.
And dripping the obtained mixed solution on a rotating disc electrode, taking the electrode as a working electrode, taking a silver/silver chloride electrode as a reference electrode, and taking a graphite rod as a counter electrode. Then introducing nitrogen and carrying out electrochemical reaction in an H-type electrolytic cell to obtain the ammonia.
The experimental result shows that the product is similar to LaCoO in the prior art3The nanometer material is used as a catalyst for comparison, and LaCoO is applied to the overpotential of-0.6V relative to a standard hydrogen electrode in the reaction of synthesizing ammonia by electrochemically reducing nitrogen3Nanocatalyst and LaCoO having surface oxygen vacancies3The nano catalyst has Faraday efficiencies of 2.3% and 7.6%, respectively, and has effective current densities of 7.5 microamperes/square centimeter and 20.9 microamperes/square centimeter and ammonia production rates of 66.1 micrograms/milligram of catalyst/hour and 183.1 micrograms/milligram of catalyst/hour under overpotential of-0.7V relative to a standard hydrogen electrode. Thus, the LaCoO having surface oxygen vacancies for use in the present invention3Compared with other catalytic materials, the nano-catalyst is easy to synthesize in large quantity and has low cost. In the catalytic reaction, the catalyst used in the invention has high selectivity and good stability.
For a further understanding of the present invention, the following examples are included to provide LaCoO with surface oxygen vacancies in accordance with the present invention3The preparation method of the nanometer and the application thereof are explained in detail, and the protection scope of the invention is not limited by the following examples.
Example 1
The invention provides a LaCoO with surface oxygen vacancy3The nano catalyst has an average size of 60-100 nm, and the synthesis method comprises the following steps:
dissolving lanthanum nitrate hexahydrate, cobalt acetate tetrahydrate, urea and citric acid monohydrate in 30mL of water, wherein the concentrations of the lanthanum nitrate hexahydrate and the cobalt acetate tetrahydrate are both 0.125 mol/L and the concentrations of the urea and the citric acid monohydrate are both 0.5 mol/L, adding 3 mL of concentrated nitric acid, uniformly mixing, heating to 80 ℃, and magnetically stirring until gel is generated; then dried at 170 ℃ for 12 hours, and the obtained sample is calcined at 600 ℃ for 6 hours under oxygen to obtain LaCoO3And (3) a nano catalyst.
Mixing LaCoO3Placing the nano catalyst in argon plasma with power supply power of 200W and argon pressure maintained at 10 Torr, etching the zinc oxide nano sheet by the argon plasma for 30 minutes to obtain LaCoO with surface oxygen vacancy3And (3) a nano catalyst.
LaCoO with surface oxygen vacancies3The picture of the scanning electron microscope of the nano-catalyst is shown in figure 1, the picture of the transmission electron microscope is shown in figure 2, and the picture of the high-resolution transmission electron microscope is shown in figure 3The X-ray diffraction spectrum of the zinc oxide nano sheet with the oxygen-rich vacancy and the original zinc oxide nano sheet is shown in figure 4, and the X-ray photoelectron energy spectrum is shown in figure 5.
Example 2
3 mg of LaCoO having surface oxygen vacancies3Dispersing a nano catalyst, 12 mg of activated carbon and 100 microliters of 5% mass fraction Nafion solution in 2.9 milliliters of ethanol, and performing ultrasonic treatment for 1 hour to obtain a uniform solution; then, 5 microliters of the solution is uniformly dripped on a rotating disk electrode with the diameter of 0.5 cm, the rotating disk electrode is used as a working electrode, a silver/silver chloride electrode is used as a reference electrode, a graphite rod is used as a counter electrode, 30 milliliters of potassium sulfate solution with the concentration of 0.1 mol/liter is used as electrolyte, the catalytic reaction is carried out in an H-shaped electrolytic cell, the electrolytic cell is separated from a cathode and an anode by a Nafion 115 proton exchange membrane, nitrogen gas is introduced for at least 30 minutes before the reaction to drive other gases away, and the nitrogen gas is continuously introduced at the speed of 10 milliliters/minute; oxygen generated by the anode in the reaction is discharged into the air, and the concentration of ammonia generated after the reaction is finished is detected by an ultraviolet visible spectrophotometer after the indophenol blue color development reaction;
constant potential is adopted to test the reaction process, the overpotential of the standard hydrogen electrode is set to be-0.5V, and the constant potential is tested for 2 hours; in the reaction process, after the test is required to be completed, the overpotential is changed to-0.6V, -0.7V, -0.8V, -0.9V, and the test is respectively carried out by utilizing the same process. LaCoO with surface oxygen vacancies3The current density of the nano-catalyst under the overpotentials is shown in figure 6, the Faraday efficiency of ammonia production is shown in figure 7, and the ammonia production rate is shown in figure 8; as can be seen from FIG. 6, under all potential conditions tested, LaCoO with surface oxygen vacancies3The current density of the nano catalyst is higher than that of the original LaCoO3Nano catalyst and LaCoO with surface oxygen vacancy at-0.7V relative to standard hydrogen electrode3The effective current density of the nano catalyst reaches 20.9 microamperes per square centimeter, and the nano catalyst is original LaCoO32.8 times of the nano catalyst. As can be seen from FIG. 7, under all potential conditions tested, LaCoO with surface oxygen vacancies3The Faraday efficiency of the nano catalyst exceeds that of the original LaCoO3Nano meterA catalyst and LaCoO having surface oxygen vacancies at an overpotential of-0.6V relative to a standard hydrogen electrode3The nano catalyst has Faraday efficiency up to 7.6% and is original LaCoO33.3 times of the nano catalyst. As can be seen from FIG. 8, when the overpotential to the standard hydrogen electrode is-0.7V, LaCoO having surface oxygen vacancy is present3The ammonia generating rate of the nano catalyst reaches 183.1 microgram/milligramCatalyst and process for preparing sameIn terms of hours.
Example 3
LaCoO with surface oxygen vacancy under the condition that the overpotential relative to a standard hydrogen electrode is-0.7V3And (3) testing the stability of the nano catalyst in the synthesis of ammonia by electrochemically reducing nitrogen.
A potentiostatic test was carried out under the reaction conditions of example 2; setting the overpotential of a relative standard hydrogen electrode to be-0.7V, and carrying out constant potential test for 2 hours; in the reaction process, nitrogen is required to be continuously introduced at the speed of 10 ml/min, oxygen generated by an anode in the reaction is discharged into the air, and the concentration of ammonia generated after the reaction is finished is detected by an ultraviolet-visible spectrophotometer after the indophenol blue color development reaction. After the reaction is finished, the electrolyte is replaced, the same test conditions are used again, the cyclic test is carried out for 9 times, and the LaCoO with the surface oxygen vacancy3The graph of the change of the ammonia production rate of the nano catalyst under the potential along with the test times is shown in figure 9, and the LaCoO with surface oxygen vacancies after ten-cycle test is shown in figure 93The ammonia production rate of the nanocatalyst showed only about 5.5% decay, indicating that the catalyst has good stability.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. A method for synthesizing ammonia by electrochemically reducing nitrogen comprises the following steps:
mixing activated carbon, Nafion solution and LaCoO with oxygen vacancy3Dispersing the nano material in a solvent to obtain a mixed solution;
dropping the mixed solution on an electrode to be used as a working electrode, taking a graphite rod as a counter electrode, introducing nitrogen, and then carrying out electrochemical reaction in an H-shaped electrolytic cell to obtain ammonia;
the LaCoO with surface oxygen vacancy3A method of preparing a nanomaterial comprising:
mixing LaCoO3Etching the nano material in argon plasma to obtain LaCoO with surface oxygen vacancy3And (3) nano materials.
2. The method of claim 1, wherein the argon plasma etching has a power supply power of 180 to 250 watts.
3. The method of claim 1, wherein the argon pressure of the argon plasma is 8-15 torr, and the etching time is 20 min-1 h.
4. The method of claim 1, wherein the LaCoO having surface oxygen vacancies3The average size of the nano material is 60 nm-100 nm.
5. The method of claim 1, wherein the LaCoO is present in the sample3The preparation method of the nano material comprises the following steps:
mixing a lanthanum source, a cobalt source, urea, citric acid monohydrate, water and concentrated nitric acid to obtain gel;
heating the gel, drying and finally calcining to obtain LaCoO3And (3) nano materials.
6. The method of claim 5, wherein the lanthanum source is lanthanum nitrate hexahydrate, the cobalt source is cobalt nitrate tetrahydrate, the concentrations of the lanthanum nitrate hexahydrate and the cobalt nitrate tetrahydrate are each 0.1 to 0.2 moles/liter, and the concentrations of the urea and the citric acid monohydrate are each 0.2 to 0.8 moles/liter.
7. The method according to claim 5, wherein the heating temperature is 80 to 100 ℃, the drying temperature is 150 to 200 ℃, and the calcining temperature is 550 to 650 ℃.
8. The method of claim 1, wherein the activated carbon is reacted with the LaCoO having oxygen vacancies3The mass ratio of the nano material is 4: 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910599150.1A CN110227474B (en) | 2019-07-04 | 2019-07-04 | LaCoO with oxygen vacancy3Preparation method and application of nano material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910599150.1A CN110227474B (en) | 2019-07-04 | 2019-07-04 | LaCoO with oxygen vacancy3Preparation method and application of nano material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110227474A CN110227474A (en) | 2019-09-13 |
| CN110227474B true CN110227474B (en) | 2020-05-22 |
Family
ID=67858007
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910599150.1A Active CN110227474B (en) | 2019-07-04 | 2019-07-04 | LaCoO with oxygen vacancy3Preparation method and application of nano material |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110227474B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111766289B (en) * | 2020-06-22 | 2022-08-30 | 济南大学 | Oxygen-enriched vacancy CeO 2 Preparation method of electrochemiluminescence immunosensor |
| CN112718018B (en) * | 2020-12-10 | 2023-08-25 | 昆明理工大学 | Lanthanum cobaltite perovskite catalyst treated by acetic acid and preparation method thereof |
| CN114686916A (en) * | 2022-03-07 | 2022-07-01 | 深圳先进技术研究院 | Zinc oxide nanorod array photoanode and preparation method thereof |
| CN114990582B (en) * | 2022-06-28 | 2023-08-22 | 燕山大学 | Bimetal oxide OV-NiMnO 3 Microsphere and preparation method thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109420512A (en) * | 2017-09-04 | 2019-03-05 | 中国科学院上海硅酸盐研究所 | A kind of catalysis material and its preparation method and application based on phosphoric acid modification |
-
2019
- 2019-07-04 CN CN201910599150.1A patent/CN110227474B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN110227474A (en) | 2019-09-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Hu et al. | Recent progress made in the mechanism comprehension and design of electrocatalysts for alkaline water splitting | |
| CN110227474B (en) | LaCoO with oxygen vacancy3Preparation method and application of nano material | |
| Guo et al. | Electrochemical nitrogen fixation and utilization: theories, advanced catalyst materials and system design | |
| Zhang et al. | High-efficiency electrosynthesis of ammonia with high selectivity under ambient conditions enabled by VN nanosheet array | |
| Zhao et al. | Recent progress in the electrochemical ammonia synthesis under ambient conditions | |
| Chen et al. | Mn-doped RuO2 nanocrystals as highly active electrocatalysts for enhanced oxygen evolution in acidic media | |
| Xie et al. | Oxygen vacancies of Cr-doped CeO2 nanorods that efficiently enhance the performance of electrocatalytic N2 fixation to NH3 under ambient conditions | |
| Cao et al. | Aqueous electrocatalytic N 2 reduction under ambient conditions | |
| Zhao et al. | Highly efficient metal–organic-framework catalysts for electrochemical synthesis of ammonia from N 2 (air) and water at low temperature and ambient pressure | |
| Niu et al. | Effect on electrochemical reduction of nitrogen to ammonia under ambient conditions: Challenges and opportunities for chemical fuels | |
| Chen et al. | Ambient dinitrogen electrocatalytic reduction for ammonia synthesis | |
| CN109680299B (en) | Three-dimensional self-supporting gamma-Fe2O3-NC/CF electrode and preparation method and application thereof | |
| Yan et al. | B-doped graphene quantum dots implanted into bimetallic organic framework as a highly active and robust cathodic catalyst in the microbial fuel cell | |
| Salonen et al. | Sustainable catalysts for water electrolysis: Selected strategies for reduction and replacement of platinum-group metals | |
| CN113235113B (en) | Hollow carbon-coated copper oxide nanoparticle catalyst and preparation method and application thereof | |
| CN113789542B (en) | Copper-based catalyst, preparation method thereof, catalytic electrode for electrocatalytic reduction of carbon dioxide and application | |
| Li et al. | Efficient electrochemical NO reduction to NH3 over metal-free g-C3N4 nanosheets and the role of interface microenvironment | |
| Jiang et al. | Rare earth oxide based electrocatalysts: synthesis, properties and applications | |
| CN109499602A (en) | A kind of synthetic method of systematization regulation loading type iron elementide atom number | |
| Yin et al. | Efficient electrocatalytic properties of transition metal (Mn, Co, Cu) doped LaFeO3 for ammonia synthesis via nitrate reduction | |
| Li et al. | Recent advances of metal oxide catalysts for electrochemical NH3 production from nitrogen-containing sources | |
| CN108842165B (en) | Solvothermal preparation of sulfur doped NiFe (CN)5NO electrolysis water oxygen evolution catalyst and application thereof | |
| CN114045524B (en) | Iridium monoatomic catalyst, preparation method and application thereof | |
| Chang et al. | Lattice distortion of PtCo nanoparticles encapsulated in TiO2 nanotubes boosts methanol oxidation | |
| Cao et al. | Enhanced activity of mesoporous SrCo0. 8Fe0. 1Nb0. 1O3-δ perovskite electrocatalyst by H2O2 treatment for oxygen evolution reaction |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |