CN113897626A - Au/VO2Composite nano catalyst and preparation method thereof - Google Patents

Au/VO2Composite nano catalyst and preparation method thereof Download PDF

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CN113897626A
CN113897626A CN202111200061.9A CN202111200061A CN113897626A CN 113897626 A CN113897626 A CN 113897626A CN 202111200061 A CN202111200061 A CN 202111200061A CN 113897626 A CN113897626 A CN 113897626A
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catalyst
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CN113897626B (en
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郭倚天
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Guangdong Electronic Information Engineering Research Institute of UESTC
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    • 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
    • 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
    • C25B11/093—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 at least one noble metal or noble metal oxide and at least one non-noble metal oxide
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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  • Chemical Kinetics & Catalysis (AREA)
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Abstract

The application discloses Au/VO2A composite nano catalyst and a preparation method thereof. The Au/VO2VO in composite nano catalyst2Is of coralline nanostructure, and VO2Is oxygen-rich defect VO2Au is nanocluster and is uniformly anchored on the VO2The above step (1); the oxygen-enriched defect treatment of the vanadium dioxide provides richer and strong-binding-force anchoring sites for the Au nanoclusters, the electron transfer between the nanoclusters and the carrier is promoted, the local metal phase change of the vanadium dioxide at room temperature can be realized through a gold-vanadium dioxide composite structure, the interface hydrogenation process is favorable for promoting the interface electron transfer, the effective utilization rate of gold atoms can be obviously improved, and the high catalytic activity of the gold atoms is exerted. The preparation method of the catalyst provided by the invention has the advantages of simple process steps, high safety and convenience in large-scale production.

Description

Au/VO2Composite nano catalyst and preparation method thereof
Technical Field
The invention relates to the technical field of catalysts, and particularly relates to Au/VO2A composite nano catalyst and a preparation method and application thereof.
Background
With the gradual development of society, the excessive dependence of human beings on fossil energy has led to the increase of the emission of greenhouse gases such as carbon dioxide year by year; in order to reduce the influence of greenhouse effect and reduce the emission of carbon dioxide, energy conservation and emission reduction and low-carbon life are advocated in recent years, the emission of carbon dioxide is slowed down, but the whole emission still tends to rise, and a substance which can replace fossil fuel in partial scenes to serve as energy or energy storage is needed to provide a new way for reducing the emission of carbon.
Due to the characteristics of high energy density, environment-friendly combustion products, rich reserves of preparation raw materials and low cost of ammonia, the ammonia is an indispensable basic industrial raw material and clean energy candidate in a future green industrial system; the method for preparing ammonia by electrocatalysis nitrogen fixation, namely, the method for electrolyzing by utilizing electric power generated by clean energy sources such as solar energy, wind energy, geothermal energy and the like replaces the Haber-Bosch method in the traditional ammonia preparation industry, can obviously reduce the environmental pollution, the emission of carbon and harmful gases, and belongs to a new green ammonia preparation way.
In order to overcome the high potential barrier required for dissociating nitrogen-nitrogen triple bonds in the electrolysis process, a nitrogen fixation catalyst with high activity and low cost is needed.
Disclosure of Invention
The invention aims to provide Au/VO for fixing nitrogen2The composite nanometer catalyst is prepared with ammonium metavanadate as reactant, high temperature sintering and hydrogen annealing to obtain vanadium dioxide with oxygen-rich defect, and soaking the product in tetrachloroauric acid aqua to obtain Au/VO2A composite nano-catalyst. The oxygen-rich defect treatment of the vanadium dioxide provides richer and strong-bonding-force anchoring sites for the Au nanoclusters, promotes the electron transfer between the nanoclusters and the carrier, and improves the nitrogen fixation performance of the catalyst.
According to an aspect of the present invention, there is provided an Au/VO2The composite nano catalyst is characterized in that the VO2Is of a coralline nano structure, the Au is a nanocluster, and the Au is uniformly anchored on the VO2The particle size of the Au nanoclusters is 50-100 nm.
Preferably, the VO2Is oxygen-rich defect VO2。
Preferably, the Au/VO2The composite nano catalyst is used for electrocatalysis nitrogen fixation reaction.
According to another aspect of the present invention, there is provided an Au/VO2The preparation method of the composite nano catalyst is characterized by comprising the following steps: sintering ammonium metavanadate powder at a high temperature, and cooling to room temperature to obtain a first product; placing the first product into a mixed atmosphere of hydrogen and argon, sintering at a high temperature, and cooling to room temperature to obtain a second product; putting the second product into a tetrachloroauric acid aqueous solution to obtain a mixed solution; and (3) carrying out solid-liquid separation on the mixed solution, taking out the solid and drying in vacuum to obtain the Au/VO2 composite nano catalyst as claimed in claim 1.
Preferably, the cooling of the ammonium metavanadate powder to room temperature after high-temperature sintering comprises: putting a quartz boat containing ammonium metavanadate powder into a tube furnace, and vacuumizing the interior of the tube furnace; and introducing argon into the tubular furnace, sintering the ammonium metavanadate powder in the argon atmosphere at the temperature of 600-800 ℃, preserving the temperature for at least 3 hours, and cooling to room temperature.
Preferably, the step of placing the first product into a mixed atmosphere of hydrogen and argon to perform high-temperature sintering, and then cooling to room temperature comprises the following steps: and introducing a mixed gas of hydrogen and argon into the tubular furnace, sintering the first product at the temperature of 620-680 ℃ in a mixed atmosphere of hydrogen and argon, preserving the temperature for 10-40 minutes, and cooling to room temperature.
Preferably, the volume ratio of the hydrogen in the mixed gas of the hydrogen and the argon is not less than 20%, and the volume flow of the mixed gas is not less than 30 sccm.
Preferably, the second product is uniformly dispersed into an aqueous tetrachloroauric acid solution, further comprising: the ultrasonic treatment is carried out for not less than 10 minutes.
Preferably, the molar amount of solute in the aqueous tetrachloroauric acid solution is at least 1.6 times the molar amount of the second product.
Preferably, the concentration of the tetrachloroauric acid aqueous solution is not less than 5 mmol/L.
The Au/VO provided by the invention2Composite structure nano catalyst and preparation method thereofThe vanadium dioxide in the composite structure is vanadium dioxide with oxygen-rich defect, the vanadium dioxide is used as a carrier in the catalyst and is in a coral shape, gold is a metal nanocluster with the particle size of 50-100nm, the gold is anchored on the vanadium dioxide carrier, local metal state phase change of the vanadium dioxide at room temperature can be realized through the gold-vanadium dioxide composite structure, the interface hydrogenation process is beneficial to promoting interface electron transfer, and meanwhile, the effective utilization rate of gold atoms can be remarkably improved, and the high catalytic activity of the vanadium dioxide is exerted. The preparation method of the catalyst provided by the invention has the advantages of simple process steps, high safety and convenience in large-scale production. Furthermore, the catalyst provided by the invention not only has a water-soluble ammonia yield obviously superior to that of the existing electrocatalytic nitrogen fixation catalytic material at normal temperature, but also has good continuous electrolytic stability, and can still maintain high catalytic activity and almost have no attenuation after long-time electrolysis.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.
FIG. 1 shows Au/VO provided by a first embodiment of the present invention2The flow diagram of the preparation method of the composite nano catalyst;
FIG. 2 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2Scanning electron microscope image of the composite nano-catalyst;
FIG. 3 shows Au/VO provided by the first embodiment of the present invention2An X-ray diffraction pattern of a first product in the preparation method of the composite nano-catalyst;
FIG. 4 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2The X-ray photoelectron spectrum full spectrogram of the composite nano catalyst;
FIG. 5 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2A narrow-spectrum X-ray photoelectron energy spectrum of gold in the composite nano catalyst;
FIG. 6 is a drawing showingAu/VO provided by the first embodiment of the invention2Au/VO obtained in preparation method of composite nano catalyst2A narrow-spectrum X-ray photoelectron energy spectrum of vanadium in the composite nano catalyst;
FIG. 7 shows Au/VO provided by a second embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2A narrow-spectrum X-ray photoelectron energy spectrum of vanadium in the composite nano catalyst;
FIG. 8 shows Au/VO provided by an embodiment of the present invention2In the preparation method of the composite nano catalyst, a vanadium dioxide Raman test chart is obtained under different hydrogen and sintering times;
FIG. 9 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2The water-soluble ammonia yield/Faraday efficiency-overpotential diagram of the composite nano catalyst;
FIG. 10 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2A cycle performance diagram of the composite nano catalyst under a preset potential;
FIG. 11 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2An electrocatalytic nitrogen fixation reaction performance diagram of the composite nano catalyst is respectively tested in nitrogen and argon saturated electrolyte alternately;
FIG. 12 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2The nitrogen fixation performance of the composite nano catalyst and other component catalysts is shown schematically.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings. Like materials are denoted by like reference numerals throughout the various figures. Moreover, certain well-known elements may not be shown for brevity.
In the following description, numerous specific details of the invention, such as equipment, materials, dimensions, processing techniques and techniques used, are set forth in order to provide a thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.
FIG. 1 shows Au/VO provided by a first embodiment of the present invention2The flow diagram of the preparation method of the composite nano catalyst. As shown in FIG. 1, the Au/VO2The preparation method of the composite nano catalyst comprises the following steps.
In step S10, sintering the ammonium metavanadate powder at a high temperature, and cooling the sintered ammonium metavanadate powder to room temperature to obtain a first product; wherein, ammonium metavanadate powder holds in the quartz boat, and the tubular furnace is put into to the quartz boat, lets in argon gas after carrying out the evacuation to the tubular furnace, heats gradually to the target temperature and keeps warm for a certain time in the argon atmosphere, then natural cooling to room temperature, acquires the hypoxemia defect vanadium dioxide that obtains by ammonium metavanadate decomposition, first product promptly.
The specific operation comprises the following steps: 1.5g of ammonium metavanadate powder is intensively placed in the center of a quartz boat, the quartz boat is placed in a central temperature zone of a tubular furnace, 40sccm argon is introduced into the tubular furnace after the tubular furnace is vacuumized, the temperature is raised to 700 ℃ at the temperature rise rate of 5 ℃/min under the protection of argon atmosphere, the temperature is kept for 3 hours, so that the ammonium metavanadate is decomposed into low-oxygen defect vanadium dioxide, namely a first product, and then the first product is naturally cooled to the room temperature.
In step S20, placing the first product into a mixed atmosphere of hydrogen and argon, performing high-temperature sintering, and cooling to room temperature to obtain a second product; and step S10, introducing a mixed gas of hydrogen and argon into the tube furnace, gradually heating the first product to another target temperature in the mixed atmosphere, keeping the temperature for a preset time to manufacture oxygen-rich defects, and naturally cooling to room temperature to obtain the vanadium dioxide with the oxygen-rich defects, namely a second product.
The specific operation comprises the following steps: introducing a mixed gas of 40sccm hydrogen and argon into the tubular furnace, wherein the content of the hydrogen in the mixed gas is 30 percent for example, raising the temperature to 650 ℃ at a temperature raising rate of 5 ℃/min in the mixed atmosphere, keeping the temperature for 30min for annealing, and the mixed atmosphere of the hydrogen and the argon is used for manufacturing oxygen-rich defects to form oxygen-rich defect vanadium dioxide, namely a second product, and then naturally cooling to room temperature.
In step S30, the second product is put into an aqueous tetrachloroauric acid solution to obtain a mixed solution; and uniformly dispersing the second product into a tetrachloroauric acid aqueous solution, and carrying out ultrasonic treatment to fully mix the second product and the tetrachloroauric acid aqueous solution to obtain a mixed solution.
The specific operation comprises the following steps: 1mg of the second product obtained in the above step S20 was uniformly dispersed in 4ml of an aqueous tetrachloroauric acid solution having a solute content of, for example, 5mmol/L, and subjected to ultrasonic treatment for 10 minutes to obtain a mixed solution.
In step S40, the mixed solution is subjected to solid-liquid separation, and the solid is taken out and dried in vacuum to obtain Au/VO2A composite nano-catalyst. And carrying out solid-liquid separation on the mixed solution by adopting a centrifugal machine, taking out the solid in the mixed solution, and carrying out vacuum drying to obtain the finally required catalyst.
The specific operation comprises the following steps: centrifuging the mixed solution by a centrifuge, and vacuum drying the solid product at 60 ℃ for 3h to obtain Au/VO2The vanadium dioxide in the composite nano catalyst is oxygen-rich defect vanadium dioxide.
Furthermore, the invention also provides Au/VO2The preparation method of the composite nano-catalyst is taken as a second embodiment, and compared with the first embodiment, the method steps of the second embodiment are the same as those of the first embodiment, and only the parameters in the steps are different, so detailed operations are not repeated.
In the second embodiment, the flow rate of argon gas introduced in step S10 was changed to 50 sccm; in step S20, the heat retention time was changed to 15 min; in step S30, the solute content of the tetrachloroauric acid aqueous solution becomes 10 mmol/L; the ultrasonic treatment time is changed to 20 min; in step S40, the vacuum drying time of the solid product became 6 h.
Compared with the first embodiment, the concentration of the tetrachloroauric acid aqueous solution in step S30 is increased to affect the gold loading amount in the second embodiment, and the ultrasonic treatment time is lengthened to promote the gold formation.
The above two embodiments only provide individually available parameters and ratios to prepare a small amount of samples, and of course, in the preparation method provided by the present invention, the sintering temperature of step S10 can be 600-; in step S20, the volume ratio of hydrogen in the mixed gas of hydrogen and argon is not less than 20%, the flow rate of the mixed gas is not less than 30sccm, the sintering temperature is 620-680 ℃ for example, and the heat preservation time is 10-40 min; further, in step S30, the concentration of the tetrachloroauric acid aqueous solution is not less than 5mmol/L, and the molar amount of the solute in the tetrachloroauric acid aqueous solution is at least 1.6 times the molar amount of the second product (oxygen-rich defective vanadium dioxide).
FIG. 2 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2Scanning electron microscope image of the composite nano-catalyst; as can be seen from fig. 2, in the catalyst, vanadium dioxide is used as a carrier, which is in the shape of porous coral, and gold is uniformly anchored on the vanadium dioxide carrier as nanoclusters, wherein the vanadium dioxide is oxygen-rich defective vanadium dioxide, and the particle size of the gold nanoclusters is, for example, 50-100 nm.
Au/VO of the invention2The mechanism of the composite nano catalyst is as follows:
firstly, the Au nanoclusters are used as nitrogen fixation active sites, have larger surface area due to smaller particle size, and are beneficial to full exposure of the active sites and improvement of the utilization rate of Au atoms, so that the minimum requirement on the input amount of gold elements is reduced; secondly, the oxygen-enriched defect treatment of the vanadium dioxide provides richer and strong-binding-force anchoring sites for the Au nanoclusters, so that the electron transfer between the nanoclusters and the carrier is promoted, and the coral-shaped structure of the vanadium dioxide carrier also provides staggered and longitudinal and transverse electronic channels, so that the conductivity of the material is improved, and the intrinsic catalytic activity of the material is further improved; in addition, the difference of the work functions of gold and vanadium dioxide promotes the hydrogenation process at the contact interface of the gold and the vanadium dioxide, more proton raw materials are provided for nitrogen fixation sites on the gold nanocluster, and the vanadium dioxide at the contact interface is induced to generate local metal phase change, so that the conductivity is further improved; therefore, in the Au/VO of the invention2In the composite nano catalyst, gold and vanadium dioxide can be intermingledAnd by full cooperation, the nitrogen fixation catalytic performance is obviously improved by the composite structure.
FIG. 3 shows Au/VO provided by the first embodiment of the present invention2In the preparation method of the composite nano-catalyst, the X-ray diffraction pattern of the first product and the diffraction pattern in figure 3 accurately correspond to the diffraction peak information of a vanadium dioxide standard PDF card, and the main component of the first product can be determined to be vanadium dioxide.
FIG. 4 and FIG. 5 show Au/VO provided by the first embodiment of the present invention, respectively2Au/VO obtained in preparation method of composite nano catalyst2As can be seen from FIGS. 4 and 5, the product obtained by the preparation method of the present invention contains gold elements, and the gold elements are widely present in the product.
FIGS. 6 and 7 show Au/VO provided by the first and second embodiments of the invention, respectively2Au/VO obtained in preparation method of composite nano catalyst2A narrow-spectrum X-ray photoelectron energy spectrum of vanadium in the composite nano catalyst; as can be seen from fig. 6, tetravalent vanadium and pentavalent vanadium are simultaneously present in the product obtained by the first embodiment of the preparation method of the present invention, which indicates that the actual product contains vanadium dioxide and vanadium pentoxide, the reason that the signal intensity of vanadium pentoxide is large is due to surface oxidation of vanadium dioxide in air, and the significant signal of vanadium dioxide indicates the successful preparation of vanadium dioxide. By combining the accurate correspondence between the spectrum of the first product in fig. 3 and the diffraction peak information of the standard PDF card of vanadium dioxide, and the absence of an obvious vanadium pentoxide peak position, it can be further confirmed that vanadium pentoxide is only distributed in the surface layer with a surface of about 10nm, and the content is extremely low.
Comparing fig. 7 with fig. 6, both tetravalent and pentavalent vanadium are present, indicating that the actual product contains vanadium dioxide and vanadium pentoxide. However, the difference is that in fig. 7, the ratio of the tetravalent vanadium strength in vanadium is lower, the ratio of the pentavalent vanadium strength is higher, and the vanadium in the high oxidation state is more, which indicates that the content of oxygen defects (i.e. the degree of reduction) in the vanadium dioxide composition obtained in the second embodiment of the present invention is lower, and it is verified that the annealing time length in the hydrogen and helium mixed gas is in positive correlation with the content of oxygen defects.
In conjunction with FIGS. 4 and 5, it is presumed that a complex of gold and vanadium dioxide, i.e., Au/VO, is formed by the preparation method2A composite nano-catalyst.
FIG. 8 shows Au/VO provided by an embodiment of the present invention2In the preparation method of the composite nano catalyst, a raman signal of vanadium dioxide under different hydrogen and sintering times is shown in fig. 8, and a raman signal of a product mainly comprises vanadium dioxide and vanadium pentoxide, and the strength of the reduced vanadium trioxide is gradually increased along with the extension of annealing time in a mixed gas of hydrogen and helium, which shows that the adjustment and control of the annealing time has a promoting effect on the oxygen-rich defect of the prepared vanadium dioxide.
FIG. 9 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2The water-soluble ammonia yield/Faraday efficiency-overpotential diagram of the composite nano-catalyst is shown in FIG. 9, and is 0.1mol/L Na2SO4Au/VO prepared according to the first embodiment of the present invention as an electrolyte (neutral)2The composite nano catalyst obtains the optimal electrocatalytic nitrogen fixation performance under the potential of-0.55V vs. RHE, and the Yield (Yield) of water-soluble ammonia can reach 27.86 mu g mgcat-1h-1And the faradic Efficiency (Faraday Efficiency) of the reaction reaches 25.46 percent, which indicates that the Au/VO provided by the invention2The composite nano catalyst is one of the best choices (efficiency) of the prior high-activity electrocatalytic nitrogen fixation catalyst>20% and yield>20μg mgcat-1h-1)。
FIG. 10 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2The cycle performance diagram of the composite nano-catalyst under the preset potential, the cycle test of FIG. 10 shows that the Au/VO of the invention2The composite nano catalyst can still keep higher electrocatalytic nitrogen fixation activity after 32h electrolysis, which shows that the material can keep good stability under the electrolysis condition.
FIG. 11 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2Composite type nano-tubeAn electrocatalytic nitrogen fixation reaction performance diagram of the rice catalyst is respectively tested in nitrogen and argon saturated electrolyte alternately; as can be seen from FIG. 11, Au/VO of the present invention2Nitrogen reduction products in nitrogen fixation reaction applicable to composite nano-catalyst take ammonia as main component and hydrazine (N) as byproduct2H4) Negligible, indicating that the catalyst of this example has a high reaction selectivity, ammonia is produced in large quantities almost exclusively under nitrogen-saturated electrolyte conditions, indicating that the main source of ammonia produced by the nitrogen fixation reaction is dissolved nitrogen.
FIG. 12 shows Au/VO provided by the first embodiment of the present invention2Au/VO obtained in preparation method of composite nano catalyst2The nitrogen fixation performance of the composite nano-catalyst and other component catalysts is shown schematically in FIG. 12, Au/VO2Is Au/VO prepared by the method of the first embodiment of the invention2Composite type nano catalyst, VO2The vanadium dioxide, d-VO, is obtained in step S10 of the method of the first embodiment of the present invention2The oxygen-rich defect vanadium dioxide produced in step S20 in the prevention of the first embodiment of the present invention, CP is carbon paper. As can be seen from FIG. 12, Au/VO prepared according to the first embodiment of the present invention2The performance of the composite nano catalyst is obviously superior to the superposition of the performances of all the components, which shows that the Au/VO provided by the invention2The composite structure in the composite nano-catalyst produces a remarkable synergistic effect.
In conclusion, the Au/VO provided by the invention2The vanadium dioxide in the composite structure is vanadium dioxide with oxygen-rich defect, the vanadium dioxide is used as a carrier in the catalyst and is in a coral shape, gold is a metal nanocluster with the particle size of 50-100nm, and the gold is anchored on the vanadium dioxide carrier, so that local metal state phase change of the vanadium dioxide at room temperature can be realized through the gold-vanadium dioxide composite structure, the interface hydrogenation process is favorable for promoting interface electron transfer, and meanwhile, the effective utilization rate of gold atoms can be remarkably improved, and the high catalytic activity of the gold atoms is exerted. The preparation method of the catalyst provided by the invention has the advantages of simple process steps, high safety and convenience in large-scale production. Further, the present invention provides a catalyst, not onlyThe yield of water-soluble ammonia at normal temperature is obviously superior to that of the existing electrocatalytic nitrogen fixation catalytic material, and the material also has good continuous electrolytic stability, and can still maintain high catalytic activity and almost not attenuate after long-time electrolysis.
In the above description, technical details of each apparatus involved in the production, and the model of the apparatus, etc. are not described in detail. It will be appreciated by those skilled in the art that the desired sintering environment, gas atmosphere, etc. may be created by various technical means. While the invention has been described in connection with specific embodiments thereof, which are set forth for the purpose of illustration only, and not for the purpose of limiting the same, it is to be understood that the invention is not limited to the disclosed features but, unless otherwise specified, may be substituted for other equivalent or alternative features serving the same purpose; all of the features, methods, or steps of the processes disclosed herein can be combined in any manner, except for mutually exclusive features and/or steps. The scope of the invention is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the invention, and these alternatives and modifications are intended to fall within the scope of the invention.

Claims (10)

1. Au/VO2The composite nano catalyst is characterized in that the VO2Is of a coralline nano structure, the Au is a nanocluster, and the Au is uniformly anchored on the VO2The particle size of the Au nanoclusters is 50-100 nm.
2. The nanocatalyst of claim 1, wherein the VO is comprised of2Is oxygen-rich defect VO2。
3. The nanocatalyst of claim 1, wherein the Au/VO is2The composite nano catalyst is used for electrocatalysis nitrogen fixation reaction.
4. Au/VO2The preparation method of the composite nano catalyst is characterized in thatThe method comprises the following steps:
sintering ammonium metavanadate powder at a high temperature, and cooling to room temperature to obtain a first product;
placing the first product into a mixed atmosphere of hydrogen and argon, sintering at a high temperature, and cooling to room temperature to obtain a second product;
putting the second product into a tetrachloroauric acid aqueous solution to obtain a mixed solution;
subjecting the mixture to solid-liquid separation, taking out the solid and vacuum drying to obtain Au/VO according to claim 12A composite nano-catalyst.
5. The method according to claim 4, wherein the step of sintering the ammonium metavanadate powder at a high temperature and then cooling the sintered ammonium metavanadate powder to room temperature comprises the steps of:
putting a quartz boat containing ammonium metavanadate powder into a tube furnace, and vacuumizing the interior of the tube furnace;
and introducing argon into the tubular furnace, sintering the ammonium metavanadate powder in the argon atmosphere at the temperature of 600-800 ℃, preserving the temperature for at least 3 hours, and cooling to room temperature.
6. The preparation method of claim 4, wherein the step of placing the first product into a mixed atmosphere of hydrogen and argon to perform high-temperature sintering, and then cooling the first product to room temperature comprises the following steps:
and introducing a mixed gas of hydrogen and argon into the tubular furnace, sintering the first product at the temperature of 620-680 ℃ in a mixed atmosphere of hydrogen and argon, preserving the temperature for 10-40 minutes, and cooling to room temperature.
7. The production method according to claim 6, wherein the volume ratio of hydrogen in the mixed gas of hydrogen and argon is not less than 20%, and the volume flow rate of the mixed gas is not less than 30 sccm.
8. The method of claim 4, wherein the second product is uniformly dispersed into an aqueous tetrachloroauric acid solution, further comprising: the ultrasonic treatment is carried out for not less than 10 minutes.
9. The method of claim 4, wherein the molar amount of solute in the aqueous tetrachloroauric acid solution is at least 1.6 times the molar amount of the second product.
10. The method according to claim 4, wherein the concentration of the aqueous tetrachloroauric acid solution is not less than 5 mmol/L.
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Citations (5)

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CN108385064A (en) * 2018-01-18 2018-08-10 天津大学 A method of vanadium dioxide transmitted spectrum is regulated and controled by gold nano grain
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CN103409768A (en) * 2013-08-29 2013-11-27 中国科学院合肥物质科学研究院 Preparation method for phase-M vanadium dioxide nanometre powder
CN103556168A (en) * 2013-10-25 2014-02-05 上海师范大学 Vanadium dioxide porous nano-film and preparation method thereof
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