CN117089879A - Composite nanomaterial MoO 2 /MoS 2 Preparation of (C) and its application in electrocatalytic reduction of nitrate to ammonia synthesis - Google Patents
Composite nanomaterial MoO 2 /MoS 2 Preparation of (C) and its application in electrocatalytic reduction of nitrate to ammonia synthesis Download PDFInfo
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- CN117089879A CN117089879A CN202210517078.5A CN202210517078A CN117089879A CN 117089879 A CN117089879 A CN 117089879A CN 202210517078 A CN202210517078 A CN 202210517078A CN 117089879 A CN117089879 A CN 117089879A
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 102
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 51
- 229910002651 NO3 Inorganic materials 0.000 title claims abstract description 33
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 title claims abstract description 33
- 230000009467 reduction Effects 0.000 title claims abstract description 25
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 16
- 238000003786 synthesis reaction Methods 0.000 title claims abstract description 16
- 239000002131 composite material Substances 0.000 title claims abstract description 15
- 239000002086 nanomaterial Substances 0.000 title claims abstract description 12
- 238000002360 preparation method Methods 0.000 title claims description 8
- 101100069231 Caenorhabditis elegans gkow-1 gene Proteins 0.000 title description 2
- 239000003054 catalyst Substances 0.000 claims abstract description 37
- 238000012360 testing method Methods 0.000 claims abstract description 16
- YPJKMVATUPSWOH-UHFFFAOYSA-N nitrooxidanyl Chemical compound [O][N+]([O-])=O YPJKMVATUPSWOH-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 12
- 239000002243 precursor Substances 0.000 claims abstract description 11
- 239000008151 electrolyte solution Substances 0.000 claims abstract description 6
- 238000004729 solvothermal method Methods 0.000 claims abstract description 6
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 229910052750 molybdenum Inorganic materials 0.000 claims description 13
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 12
- 239000011733 molybdenum Substances 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 12
- 239000003792 electrolyte Substances 0.000 claims description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 10
- 238000001354 calcination Methods 0.000 claims description 9
- MGFYIUFZLHCRTH-UHFFFAOYSA-N nitrilotriacetic acid Chemical compound OC(=O)CN(CC(O)=O)CC(O)=O MGFYIUFZLHCRTH-UHFFFAOYSA-N 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 6
- 239000013110 organic ligand Substances 0.000 claims description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 5
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- 239000001257 hydrogen Substances 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- POILWHVDKZOXJZ-ARJAWSKDSA-M (z)-4-oxopent-2-en-2-olate Chemical compound C\C([O-])=C\C(C)=O POILWHVDKZOXJZ-ARJAWSKDSA-M 0.000 claims description 4
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 4
- 229910052753 mercury Inorganic materials 0.000 claims description 4
- 229920000557 Nafion® Polymers 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 238000004321 preservation Methods 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 239000007810 chemical reaction solvent Substances 0.000 claims description 2
- 239000012528 membrane Substances 0.000 claims description 2
- 230000003647 oxidation Effects 0.000 claims description 2
- 238000007254 oxidation reaction Methods 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- ARVBXAKTGHWMTM-UHFFFAOYSA-N molybdenum;pentane-2,4-dione Chemical compound [Mo].CC(=O)CC(C)=O ARVBXAKTGHWMTM-UHFFFAOYSA-N 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 18
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 4
- 230000003197 catalytic effect Effects 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract description 3
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 3
- 230000008569 process Effects 0.000 abstract description 3
- 239000003344 environmental pollutant Substances 0.000 abstract description 2
- 231100000719 pollutant Toxicity 0.000 abstract description 2
- 238000006722 reduction reaction Methods 0.000 abstract 3
- 102000004190 Enzymes Human genes 0.000 abstract 1
- 108090000790 Enzymes Proteins 0.000 abstract 1
- 239000002994 raw material Substances 0.000 abstract 1
- 239000010865 sewage Substances 0.000 abstract 1
- 239000002245 particle Substances 0.000 description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 6
- 238000001000 micrograph Methods 0.000 description 5
- 238000000634 powder X-ray diffraction Methods 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 239000007800 oxidant agent Substances 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 238000002835 absorbance Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- QXYJCZRRLLQGCR-UHFFFAOYSA-N dioxomolybdenum Chemical compound O=[Mo]=O QXYJCZRRLLQGCR-UHFFFAOYSA-N 0.000 description 2
- 238000005868 electrolysis reaction Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- YGSDEFSMJLZEOE-UHFFFAOYSA-N salicylic acid Chemical compound OC(=O)C1=CC=CC=C1O YGSDEFSMJLZEOE-UHFFFAOYSA-N 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000009210 therapy by ultrasound Methods 0.000 description 2
- 238000004627 transmission electron microscopy Methods 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 238000009620 Haber process Methods 0.000 description 1
- 239000005708 Sodium hypochlorite Substances 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000004737 colorimetric analysis Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000002484 cyclic voltammetry Methods 0.000 description 1
- XYVDNBKDAAXMPG-UHFFFAOYSA-M decyl 2-(1-heptylazepan-1-ium-1-yl)acetate;hydroxide Chemical compound [OH-].CCCCCCCCCCOC(=O)C[N+]1(CCCCCCC)CCCCCC1 XYVDNBKDAAXMPG-UHFFFAOYSA-M 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000010840 domestic wastewater Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000010411 electrocatalyst Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000012851 eutrophication Methods 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 239000011943 nanocatalyst Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- FJKROLUGYXJWQN-UHFFFAOYSA-N papa-hydroxy-benzoic acid Natural products OC(=O)C1=CC=C(O)C=C1 FJKROLUGYXJWQN-UHFFFAOYSA-N 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 235000010333 potassium nitrate Nutrition 0.000 description 1
- 239000004323 potassium nitrate Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229960004889 salicylic acid Drugs 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000001350 scanning transmission electron microscopy Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- -1 sodium nitrosoferricyanide Chemical compound 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000012086 standard solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 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 description 1
- 229940038773 trisodium citrate Drugs 0.000 description 1
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 1
- 238000004832 voltammetry Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- C25B1/01—Products
- C25B1/27—Ammonia
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Catalysts (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
The invention relates to a nanomaterial MoO 2 /MoS 2 Is used for preparing the electrocatalytic nitrate radical reduction synthetic ammonia. Comprising the following steps: (1) Catalyst MoO 2 /MoS 2 Is prepared by the steps of (1); (2) preparing an electrolyte solution; (3) testing of electrocatalytic nitrate reduction synthesis ammonia. The invention synthesizes the precursor catalyst MoO by a solvothermal method under the inspired of the Mo-based catalyst in the nitrogen fixation enzyme 2 Then optimizing the precursor catalyst to prepare the composite catalyst MoO 2 /MoS 2 The catalyst effectively improves the activity of the electrocatalytic nitrate radical reduction reaction, improves the ammonia production rate, shows higher Faraday efficiency and has relatively good stability. The catalytic material has the advantages of low raw material cost, simple synthesis process, capability of converting pollutant nitrate into ammonia, and important application value in the aspects of sewage treatment, electrocatalytic ammonia synthesis and the like。
Description
Technical Field
The invention relates to a nanomaterial MoO 2 /MoS 2 The preparation of the catalyst and the application thereof in the electrocatalytic nitrate synthesis of ammonia, and belongs to the technical field of electrocatalytic.
Background
Nitrate has been considered in recent years as the most common pollutant in groundwater, and the main sources are the large amount of nitrogen-rich fertilizers and the discharge of improperly treated domestic and industrial wastewater, and high concentration of nitrate can cause eutrophication of water bodies and threaten human health. Meanwhile, ammonia (NH 3) is a very important chemical product, and the existing industrial ammonia production mainly adopts the Haber-Bosch process, but has high energy consumption and serious pollutionAnd the like. In contrast, the process of preparing ammonia by electrocatalytic nitrate reduction is more environment-friendly, and nitrate is converted into recyclable ammonium (NH) at normal temperature and normal pressure 4 + ) Has very important significance.
Although electrocatalytic ammonia production has the advantages of low cost, mild conditions, environmental friendliness and the like and is widely developed, a plurality of problems remain unsolved: the complex eight-electron transfer way and the competition of hydrogen evolution reaction in the reaction process lead to slow dynamic process, the higher reaction energy barrier leads to low reaction activity, and the generation of byproducts leads to lower Faraday efficiency and selectivity and other problems. Therefore, designing and developing a high-efficiency catalyst, optimizing the active site on the surface of the catalyst, enhancing the adsorption and activation of nitrate, improving the performance of nitrate for reducing synthetic ammonia, inhibiting the generation of side reactions such as hydrogen evolution and the like, and is the key point of the current research field.
Disclosure of Invention
One of the purposes of the present invention is to provide MoO with low cost and high electrocatalytic performance 2 /MoS 2 A nanomaterial.
Another object of the present invention is to provide a MoO 2 /MoS 2 The nano material is used for electrocatalytic nitrate radical reduction to synthesize ammonia.
The invention is realized by the following technical scheme:
composite nanomaterial MoO 2 /MoS 2 Use for electrocatalytic nitrate reduction synthesis of ammonia, comprising the steps of:
(1) Catalyst MoO 2 /MoS 2 Is prepared from
Adding a molybdenum source and an organic ligand into a specific solvent, and preparing a precursor MoO by adopting a solvothermal method 2 The composite catalyst MoO is prepared by calcination 2 /MoS 2 ；
(2) Preparing electrolyte solution
Preparing electrolyte solution of nitrate radical with proper concentration;
(3) Test of electrocatalytic nitrate reduction synthesis ammonia
In the electrolyte prepared in the step (2), the catalyst prepared in the step (1) is used as a working electrode, a carbon rod is used as a counter electrode, a mercury oxidation mercury electrode is used as a reference electrode, and a test reaction of nitrate radical reduction synthesis ammonia is carried out in an H-type electrolytic cell reactor separated by a Nafion 117 membrane.
In the above technical scheme, the specific reaction solvent is a mixture of N, N-dimethylformamide and deionized water.
In the technical scheme, the molybdenum source is molybdenum acetylacetonate, and the concentration of the molybdenum source is 10mmol/L.
In the technical scheme, the organic ligand is nitrilotriacetic acid, and the concentration of the nitrilotriacetic acid is 5mmol/L.
In the technical scheme, the feeding molar ratio of molybdenum source molybdenum acetylacetonate to organic ligand nitrilotriacetic acid is 2:1.
In the technical scheme, the solvothermal reaction temperature is 180 ℃ and the reaction time is 6 hours.
In the technical proposal, moO 2 By at 5%H 2 And (3) calcining at low temperature in a tube furnace under the S atmosphere to introduce S element, wherein the temperature rise rate of the program in the tube furnace is 2 ℃/min, the initial temperature is room temperature, the holding temperature is 400 ℃, and the heat preservation time is 2h.
In the above technical scheme, the electrolyte is 1M KOH solution, and the concentration of nitrate radical is 25mM, 50mM, 75mM and 100mM respectively.
In the technical scheme, the reaction potential of the three-electrode system is set to be-1.0V-0V relative to a standard hydrogen electrode, the reaction temperature is room temperature, and nitrate radical is reduced to synthesize ammonia under different voltages by electrocatalytic catalysis.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a composite nano material MoO 2 /MoS 2 The preparation method is used for the application of electrocatalytic nitrate radical reduction to synthesize ammonia, the catalyst has low cost, easy preparation and simple operation, and the material is used as the catalyst for electrocatalytic nitrate radical reduction to synthesize ammonia. The yield of the ammonia synthesized by the electrocatalyst material is 1274.3 mu g h at a voltage of-0.2V -1 mg -1 The Faraday efficiency was 84%。
Drawings
FIG. 1 shows MoO prepared according to the present invention 2 X-ray powder diffraction pattern of electrocatalytic material.
FIG. 2 shows MoO prepared according to the present invention 2 Scanning electron microscope image of electrocatalytic material.
FIG. 3 shows MoO prepared according to the present invention 2 Transmission electron microscopy of electrocatalytic materials.
FIG. 4 shows MoO prepared according to the present invention 2 /MoS 2 X-ray powder diffraction pattern of electrocatalytic material.
FIG. 5 shows MoO prepared according to the present invention 2 /MoS 2 Scanning electron microscope image of electrocatalytic material.
FIG. 6 shows MoO prepared according to the present invention 2 /MoS 2 Transmission electron microscopy of electrocatalytic materials.
FIG. 7 shows MoO prepared according to the present invention 2 Ammonia yield and faraday efficiency plot for electrocatalytic materials at different potentials.
FIG. 8 shows MoO prepared according to the present invention 2 /MoS 2 Ammonia yield and faraday efficiency plot for electrocatalytic materials at different potentials.
FIG. 9 shows MoO prepared according to the present invention 2 /MoS 2 Electrocatalytic material yield and faraday efficiency plot for ammonia in nitrate electrolytes at different voltages and different concentrations.
Detailed Description
EXAMPLE 1 nanocatalyst MoO 2 /MoS 2 Is prepared from
(1) Synthesis of precursors
0.6523g of molybdenum acetylacetonate (2 mmol) and 0.1911g of nitrilotriacetic acid (1 mmol) are weighed and added into a solution of 5mL of isopropanol and 15mL of deionized water for mixing, and after stirring for 30min, the mixture is put into a 50mL reaction kettle for solvothermal reaction at 180 ℃ for 6h. The reacted solution was centrifugally washed with water and ethanol and dried at 60℃under normal pressure.
(2) Calcination to produce the final product
Drying the obtained precursor MoO 2 Grinding with mortar, placing in porcelain boat, and placing in programmed heating tube furnaceIn 5%H 2 And calcining in the S atmosphere to obtain a final product. At 5%H 2 In S atmosphere, the heating speed is recorded as 2 ℃/min, the initial temperature is room temperature, the temperature is kept at 400 ℃, the heat preservation time is 2h, and the MoO is prepared after the reaction and natural cooling to the room temperature 2 /MoS 2 A composite catalyst.
FIG. 1 shows a precursor MoO 2 The X-ray powder diffraction pattern of (2) is obtained by adopting an intelligent X-ray diffraction instrument of SmartLab 9KW model of Rigaku manufacturer of Japan, setting a scanning range of 10-85 DEG and setting the scanning speed to 15 DEG min -1 And analyzing and testing the structure and the component information of the sample. As can be seen from the figure, a precursor MoO with good crystallinity is obtained 2 (PDF#32-0671)。
FIG. 2 is a precursor MoO 2 The scanning electron microscope image of (2) can be seen that the morphology of the particle is large particles with the particle size of about 200nm formed by aggregation of a plurality of small particles.
FIG. 3 is a precursor MoO 2 The size of the small particles is about 10nm, and the particles are relatively uniformly dispersed.
FIG. 4 is a composite nanomaterial MoO 2 /MoS 2 X-ray powder diffraction pattern of (C), the measured result shows that MoO still exists 2 (PDF # 32-0671) with MoS 2 (PDF # 3701492) is generated, illustrated by the method at 5%H 2 Calcining in S atmosphere to obtain composite catalyst MoO 2 /MoS 2 。
FIG. 5 is a composite nanomaterial MoO 2 /MoS 2 The scanning electron microscope image of (c) showed no change in the particle diameter surface.
FIG. 6 is a composite nanomaterial MoO 2 /MoS 2 The transmission electron microscope image of (2) shows that the size of the aggregated small particles is still about 10nm, the particles are not collapsed, and the particles are still uniformly dispersed and have a certain gap.
TABLE 1 MoO 2 /MoS 2 Mo, S, O, C and N element content in (B)
Table 1 illustrates that the S element was introduced in a proportion of 7.86wt%.
Example 2 preparation of working electrode
(1) Cutting 1X 2cm 2 Is placed in deionized water and ethanol solution for ultrasonic treatment, and surface impurities are removed for standby.
(2) 5mg of the catalyst material to be tested is weighed and placed in a 2mL reagent bottle, and ultrasonic treatment is carried out for 2h after 10% Nafion solution and 90% ethanol mixed solution are added. The purpose is to disperse the catalyst powder in the solution, and uniformly load the dispersed solution on 1cm 2 And dried at room temperature, the catalyst loading was 0.4mg/cm 2 。
Example 3 electrochemical Performance test
(1) 40mL of 1M KOH solution and 75mM KNO were added to each side of the H-cell 3 Continuously stirring the cathode electrolytic cell, introducing high-purity Ar into the cathode chamber before testing, and removing N in the air 2 Is a function of (a) and (b).
(2) In the test, in a three-electrode system, firstly, a cyclic voltammetry is adopted for testing, and after a proper voltage window is set, the electrode potential is repeatedly scanned for multiple times through different scanning rates to activate the catalyst, wherein the scanning rate is 50mV/s.
(3) Then, the catalyst was tested by linear voltammetry in a specific voltage range, the scanning rate was 10mV/s, the curve change in the presence or absence of nitrate electrolyte was recorded, and the activity and the reaction kinetic rate of the nitrate reduction of the catalyst were qualitatively analyzed.
(4) Finally, constant voltage is applied to observe the change of electrode current in a proper voltage range through a timely current method, the electrolysis reaction of the constant voltage is carried out for 1h, and finally, the electrolyte after the reaction is collected for product detection.
Example 4 Ammonia production test
(1) Working curve drawing
And detecting the electrolyzed solution by using ammonium chloride as a standard reagent through a colorimetric method. First, a standard solution having a concentration of 0.4ppm,0.8 ppm,1.2ppm,1.6ppm,2.0ppm was prepared. Preparing a color reagent, weighing 12.5g of salicylic acid, 10g of sodium hydroxide and 12.5g of trisodium citrate, adding deionized water into a volumetric flask with a constant volume of 250mL, weighing 3.722g of sodium hypochlorite aqueous solution into a volumetric flask with a constant volume of 100mL, and weighing 0.5g of sodium nitrosoferricyanide into a volumetric flask with a constant volume of 50 mL. The prepared color developing agent, oxidant and reducer are added for developing color, and after the color developing agent, oxidant and reducer are static for 1h, the color developing agent and reducer are tested in the wavelength range of 500-800 nm. Absorbance values at 655nm were recorded and plotted against concentration to obtain a working curve.
(2) Ammonia production test
2mL of electrolyte after testing for 1h under each potential is respectively taken, 2mL of the color developing agent, 1mL of the oxidant and 0.2mL of the reducing agent are added, and the mixture is subjected to static color development for 1h under the condition of being protected from light at room temperature and then tested in the wavelength range of 500-800 nm by an ultraviolet-visible spectrophotometer. The absorbance at 655nm was recorded and the ammonia concentration was finally obtained against the working curve. After data processing and calculation, the yield of ammonia and Faraday efficiency of the catalyst to be tested are obtained.
FIG. 7 is MoO 2 The results of the ammonia yield and Faraday efficiency diagrams of the electrocatalytic material under different potentials show that the precursor MoO2 has the performance on electrocatalytic nitrate reduction and synthesis of ammonia, but the yield and Faraday efficiency values are lower, and the hydrogen evolution reaction has serious competition.
FIG. 8 is MoO 2 /MoS 2 The results of the ammonia yield and Faraday efficiency diagrams of the electrocatalytic material under different potentials show that the composite catalyst obtained after calcination optimization treatment has high catalytic activity, the ammonia yield and Faraday efficiency are greatly improved, and the Faraday efficiency is kept high in a wider voltage range.
Example 5 electrochemical testing of nitrate at different concentrations
During electrolysis of nitrate, tests were performed with nitrate solutions of different concentrations. KNO was prepared at concentrations of 25mM, 50mM, 75mM, and 100mM, respectively 3 The solution was tested, nitrate electrolytes of different concentrations were tested electrochemically in a specific voltage range and tested by meter according to the ammonia yield testThe yield of ammonia and Faraday efficiency thereof were obtained.
FIG. 9 is MoO 2 /MoS 2 The yields and Faraday efficiencies of electrocatalytic materials at different voltages and different concentrations of ammonia in nitrate electrolyte show KNO at 25mM, 50mM, 75mM and 100mM 3 The catalyst has certain catalytic performance under the concentration, and when the concentration of potassium nitrate is 75mM, the ammonia production value is maximum, the Faraday efficiency is relatively high, and the catalyst is more beneficial to the test of electrocatalytic nitrate reduction synthesis ammonia.
The invention reaches the composite catalyst MoO by a simple solvothermal-calcination method 2 /MoS 2 The composition and morphology of the catalyst were characterized by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. The prepared material is used as a working electrode, and has excellent electrochemical reduction performance of nitrate radical synthetic ammonia, and effectively improves the yield of ammonia and Faraday efficiency, so that the material has important application value in the field of electrocatalytic nitrate radical synthetic ammonia.
Claims (9)
1. Composite nanomaterial MoO 2 /MoS 2 The preparation of (2) and the application thereof in the electrocatalytic nitrate reduction synthesis of ammonia, which is characterized by comprising the following preparation steps:
(1) Catalyst MoO 2 /MoS 2 Is prepared from
Adding a molybdenum source and an organic ligand into a specific solvent, and preparing a precursor MoO by adopting a solvothermal method 2 The composite catalyst MoO is prepared by calcination 2 /MoS 2 ；
(2) Preparing electrolyte solution
Preparing electrolyte solution of nitrate radical with proper concentration;
(3) Test of electrocatalytic nitrate reduction synthesis ammonia
In the electrolyte prepared in the step (2), the catalyst prepared in the step (1) is used as a working electrode, a carbon rod is used as a counter electrode, a mercury oxidation mercury electrode is used as a reference electrode, and a test reaction of nitrate radical reduction synthesis ammonia is carried out in an H-type electrolytic cell reactor separated by a Nafion 117 membrane.
2. The method for electrocatalytic reduction of nitrate to ammonia using the catalyst of claim 1, wherein: in the step (1), the specific reaction solvent is a mixture of N, N-dimethylformamide and deionized water.
3. The method for electrocatalytic reduction of nitrate to ammonia using the catalyst of claim 1, wherein: in the step (1), the molybdenum source is molybdenum acetylacetonate, and the concentration of the molybdenum source is 10mmol/L.
4. The method for electrocatalytic reduction of nitrate to ammonia using the catalyst of claim 1, wherein: in the step (1), the organic ligand is nitrilotriacetic acid, and the concentration of the nitrilotriacetic acid is 5mmol/L.
5. The method for electrocatalytic reduction of nitrate to ammonia using the catalyst of claim 1, wherein: in the step (1), the feeding mole ratio of molybdenum source acetylacetone molybdenum to organic ligand nitrilotriacetic acid is 2:1.
6. The method for electrocatalytic reduction of nitrate to ammonia using the catalyst of claim 1, wherein: in the step (1), the solvothermal reaction temperature is 180 ℃ and the reaction time is 6 hours.
7. The method for electrocatalytic reduction of nitrate to ammonia using the catalyst of claim 1, wherein: in step (1), moO 2 By at 5%H 2 And (3) calcining at low temperature in a tube furnace under the S atmosphere to introduce S element, wherein the temperature rise rate of the program in the tube furnace is 2 ℃/min, the initial temperature is room temperature, the holding temperature is 400 ℃, and the heat preservation time is 2h.
8. The electrolyte solution of claim 2 wherein: the electrolyte was 1M KOH solution and nitrate was prepared at concentrations of 25mM, 50mM, 75mM and 100mM, respectively.
9. The test for electrocatalytic nitrate reduction synthesis ammonia according to claim 3, wherein: the reaction potential of the three-electrode system is set to be-1.0V-0V relative to a standard hydrogen electrode, the reaction temperature is room temperature, and nitrate radical is electrically catalyzed to reduce and synthesize ammonia under different voltages.
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