阅读说明：本技术 一种金-铁纳米合金催化剂的制备方法及应用 (Preparation method and application of gold-iron nano alloy catalyst ) 是由 王志江 孙堃 于 2019-09-25 设计创作，主要内容包括：一种金-铁纳米合金催化剂的制备方法及应用,它涉及一种电催化还原CO<Sub>2</Sub>制CO的催化剂制备方法及应用。本发明的目的是要解决贵金属金与银作为CO<Sub>2</Sub>还原为CO的催化材料存在价格高昂的问题。制备方法：一、制表面活性剂溶液；二、混合；三、水热反应；四、洗涤、分散；五、复合,得到金-铁纳米合金催化剂。金-铁纳米合金催化剂作为原料制备工作电极,用于电催化还原CO<Sub>2</Sub>制CO。优点：降低了金的用量,大大降低了金基催化剂工业化应用的成本。(A preparation method and application of a gold-iron nano alloy catalyst relate to the electrocatalytic reduction of CO 2 A preparation method and application of a catalyst for preparing CO. The invention aims to solve the problem that the noble metals of gold and silver are used as CO 2 The catalytic material reduced to CO has a problem of high price. The preparation method comprises the following steps: firstly, preparing a surfactant solution; secondly, mixing;thirdly, carrying out hydrothermal reaction; fourthly, washing and dispersing; and fifthly, compounding to obtain the gold-iron nano alloy catalyst. Gold-iron nano alloy catalyst used as raw material for preparing working electrode for electrocatalytic reduction of CO 2 And (5) preparing CO. The advantages are that: the consumption of gold is reduced, and the cost of the gold-based catalyst in industrial application is greatly reduced.)

1. The preparation method of the gold-iron nano alloy catalyst is characterized by comprising the following steps of:

firstly, preparing a surfactant solution: adding a surfactant into a high-boiling-point organic solvent, and stirring until the surfactant is completely dissolved to obtain a surfactant solution; the volume ratio of the mass of the surfactant to the high-boiling-point organic solvent is (0.006-0.6) g (1-100) mL;

secondly, mixing: adding a gold salt compound, a ferric salt compound and a reducing agent into a surfactant solution, and stirring and uniformly mixing at the temperature of 30-80 ℃ in an argon atmosphere to obtain a mixture; the volume ratio of the mass of the gold salt compound to the volume of the surfactant solution is (0.0093-0.93) g, (1-100) mL; the volume ratio of the mass of the ferric salt compound to the surfactant solution is (0.0088-0.88) g (1-100) mL; the volume ratio of the mass of the reducing agent to the volume of the surfactant solution is (0.064-0.64) g (1-100) mL; the reducing agent is an alcohol compound;

thirdly, hydrothermal reaction: raising the temperature of the mixture to 250-290 ℃ under the argon atmosphere, preserving the heat for 0.5-3 h at the temperature of 250-290 ℃ under the argon atmosphere, cooling to room temperature to obtain a reaction product, adding ethanol into the reaction product, performing centrifugal separation, and removing supernatant to obtain a solid product; the volume ratio of the reaction product to the ethanol is 1: 1-3;

fourthly, washing and dispersing: cleaning the solid product for 2-5 times by using an ethanol-n-hexane mixed solution to obtain a washed product; dispersing the washed product in n-hexane to obtain a dispersion: the volume ratio of the mass of the washed product to the n-hexane is (0.0028-0.985) g, (5-500) mL;

fifthly, compounding: adding the nano carbon material into the dispersion liquid, ultrasonically mixing, then centrifugally separating, removing supernatant liquid to obtain a composite solid product, and drying the composite solid product in a vacuum drying oven to obtain a gold-iron nano alloy catalyst; the volume ratio of the mass of the nano carbon material to the dispersion liquid is (0.84-84) mg (1-100) mL.

2. The method for preparing a gold-iron nano alloy catalyst according to claim 1, wherein the surfactant in the first step is one or more of oleylamine, oleic acid or polyvinyl polypyrrolidone; the high-boiling-point organic solvent is octyl ether or octadecene.

3. The method for preparing a gold-iron nano alloy catalyst according to claim 1, wherein in the step one, the surfactant is added into the high boiling point organic solvent, and the mixture is stirred at a rotation speed of 300r/min to 800r/min for 10min to 20min to obtain a surfactant solution.

4. The method according to claim 1, wherein the gold salt compound in the second step is gold acetate or chloroauric acid tetrahydrate; the ferric salt compound is ferric acetylacetonate or ferric chloride; the alcohol compound is 1, 2-hexadecanediol, ethylene glycol or glycerol.

5. The method for preparing a gold-iron nano alloy catalyst according to claim 1, wherein in the second step, the mixture is stirred at a stirring speed of 500r/min to 1200r/min for 30min to 120min at a temperature of 30 ℃ to 80 ℃ under an argon atmosphere.

6. The method for preparing a gold-iron nano-alloy catalyst according to claim 1, wherein the temperature of the mixture is raised to 250 to 290 ℃ at a heating rate of 3 to 6 ℃/min under an argon atmosphere in the third step.

7. The method for preparing a gold-iron nano-alloy catalyst according to claim 6, characterized in that the centrifugal separation is performed at 8000 r/min-15000 r/min for 1 min-5 min in the third step, and the supernatant is removed to obtain a solid product.

8. The method for preparing a gold-iron nano alloy catalyst according to claim 1, wherein the volume ratio of ethanol to n-hexane in the ethanol-n-hexane mixed solution in the fourth step is 1: 2.

9. The method for preparing a gold-iron nano alloy catalyst according to claim 1, wherein the carbon nano material is added into the dispersion liquid in the fifth step, the ultrasonic mixing is performed for 20min to 40min, then the centrifugal separation is performed at a centrifugal speed of 8000r/min to 15000r/min, the supernatant is removed to obtain a composite solid product, and the composite solid product is placed in a vacuum drying oven and dried at a temperature of 150 ℃ to 200 ℃ for 8h to 24h to obtain the gold-iron nano alloy catalyst.

10. The application of the gold-iron nano alloy catalyst is characterized in that the gold-iron nano alloy catalyst is used as a raw material for preparing a working electrode for electro-catalytic reduction of CO₂And (5) preparing CO.

Technical Field

The invention relates to an electrocatalytic reduction method for CO₂A preparation method and application of a catalyst for preparing CO.

Background

Human excessive dependenceThe natural resources consumed for the development of the human society are not sustainable, and the content of carbon dioxide in the atmosphere is rapidly increased, so that more and more environmental problems, such as greenhouse effect and the like, are caused, and the survival and the development of human beings are seriously threatened. More urgently, the demand for energy is increasing with the increase in population, the extension of human life, the development of new processes, and the like. Climate change and energy crisis gradually threaten the survival and the proliferation of human beings on the earth, and are scientific problems which must be solved by contemporary people. But CO₂The speed of changing back to carbon-based energy materials is far behind the speed of human consumption of energy materials. The detection data of 2017 in month 2 show that the CO in the atmosphere₂The concentration is as high as 406ppm, and far exceeds the safety upper limit of 350 ppm. With CO₂The closed earth carbon circulation system is accelerated by reducing the carbon-based energy materials into resources by a chemical method, so that the energy is provided, and the CO is reduced₂The content in the atmosphere is an effective way to solve the current increasingly worsening energy and environmental problems. Electrocatalytic reduction of CO₂The advantages of mild reaction conditions, no need of high temperature and high pressure, flexible operation of the equipment, capability of obtaining higher energy utilization efficiency than other chemical conversion equipment and the like are considered to be CO₂The transformation technology with the most development prospect for resource utilization.

CO can be introduced by using different metal catalysts₂Reduction to various products, currently in all CO₂Among the reduction catalyst products, CO is considered to be the most desirable product in consideration of market price and the like, because CO is a raw material for the fischer-tropsch reaction and is used for the industrial production of methane. In all metal catalysts studied at present, the noble metals gold and silver are used as catalytic materials for CO₂The reduction to CO has the highest selectivity and catalytic efficiency, wherein the gold-based catalyst reduces CO₂The Faraday efficiency of CO can reach more than 90%. However, the noble metal gold is very rare in nature and high in price, and the industrial and large-scale use of the gold-based catalyst is severely limited. Because the nano material has high specific surface under a certain massThe current research focuses on developing novel noble metal nano materials, and the size, the morphology and the components of the materials are regulated to improve the catalytic performance and the quality activity of the noble metals, so that the consumption of the noble metals is further reduced.

The existing gold-based catalyst is mainly obtained by means of regulating and controlling the size, the surface appearance, the proportion of specific sites and the like of the catalyst. Although the catalytic activity is improved, the dosage of the noble metal gold is not obviously reduced, and the quality activity of the catalyst is not obviously improved. And the reaction condition for regulating and controlling the microscopic morphology of the nano material has extremely high requirement, the steps are complex, the preparation process has very high requirement, and the industrial actual production is difficult to meet.

Disclosure of Invention

The invention aims to solve the problem that the noble metals of gold and silver are used as CO₂The catalytic material reduced to CO has the problem of high price, and provides a preparation method and application of the gold-iron nano alloy catalyst.

A preparation method of a gold-iron nano alloy catalyst comprises the following steps:

firstly, preparing a surfactant solution: adding a surfactant into a high-boiling-point organic solvent, and stirring until the surfactant is completely dissolved to obtain a surfactant solution; the volume ratio of the mass of the surfactant to the high-boiling-point organic solvent is (0.006-0.6) g (1-100) mL;

secondly, mixing: adding a gold salt compound, a ferric salt compound and a reducing agent into a surfactant solution, and stirring and uniformly mixing at the temperature of 30-80 ℃ in an argon atmosphere to obtain a mixture; the volume ratio of the mass of the gold salt compound to the volume of the surfactant solution is (0.0093-0.93) g, (1-100) mL; the volume ratio of the mass of the ferric salt compound to the surfactant solution is (0.0088-0.88) g (1-100) mL; the volume ratio of the mass of the reducing agent to the volume of the surfactant solution is (0.064-0.64) g (1-100) mL; the reducing agent is an alcohol compound;

thirdly, hydrothermal reaction: raising the temperature of the mixture to 250-290 ℃ under the argon atmosphere, preserving the heat for 0.5-3 h at the temperature of 250-290 ℃ under the argon atmosphere, cooling to room temperature to obtain a reaction product, adding ethanol into the reaction product, performing centrifugal separation, and removing supernatant to obtain a solid product; the volume ratio of the reaction product to the ethanol is 1: 1-3;

fourthly, washing and dispersing: cleaning the solid product for 2-5 times by using an ethanol-n-hexane mixed solution to obtain a washed product; dispersing the washed product in n-hexane to obtain a dispersion: the volume ratio of the mass of the washed product to the n-hexane is (0.0028-0.985) g, (5-500) mL;

fifthly, compounding: adding the nano carbon material into the dispersion liquid, ultrasonically mixing, then centrifugally separating, removing supernatant liquid to obtain a composite solid product, and drying the composite solid product in a vacuum drying oven to obtain a gold-iron nano alloy catalyst; the volume ratio of the mass of the nano carbon material to the dispersion liquid is (0.84-84) mg (1-100) mL.

Application of gold-iron nano alloy catalyst as raw material for preparing working electrode for electrocatalytic reduction of CO₂And (5) preparing CO.

The principle and the advantages of the invention are as follows: the preparation method comprises the steps of preparing a gold-iron nano alloy catalyst by using a solvothermal synthesis method, wherein a gold salt compound and an iron salt compound are used as precursors, an alcohol compound is used as a reducing agent, a high-boiling-point organic solvent is used as a reaction solvent, a surfactant is used as a nano micelle, a nano carbon material is used as a carrier; not only has simple reaction operation and great flexibility, but also has excellent catalytic reduction of CO₂Is a property of CO; secondly, the invention mixes noble metal gold and non-noble metal iron to prepare the gold-iron nano alloy catalyst for CO₂The reduced CO has high selectivity and mass activity, the Faraday efficiency reaches 95 percent under the overpotential of-1.2V, the consumption of gold is reduced, and the cost of the industrial application of the gold-based catalyst is greatly reduced. Thirdly, the invention uses the nano carbon material as a carrier of the gold-iron alloy nano particles. Thus, the amount of the catalyst used per unit area of the electrode can be reduced, the conductivity of the catalyst can be increased, and the catalytic performance of the catalyst can be further improved. The gold-iron nano particles are tightly adsorbed on the surface of the carbon material and are uniformDispersing, preventing the nano particles from agglomerating and improving the stability of the catalyst.

Drawings

FIG. 1 is a high-resolution TEM image of the Au-Fe nanoalloy catalyst prepared in example 1;

FIG. 2 is a HAADF-STEM diagram of the gold-iron nano-alloy catalyst prepared in example 1;

FIG. 3 is a Mapping diagram of Au elements in the A region of FIG. 2;

FIG. 4 is a Mapping diagram of the Fe element of the A region in FIG. 2;

FIG. 5 is an overlay of FIGS. 3 and 4;

FIG. 6 is an EDX elemental analysis chart of the gold-iron nano-alloy catalyst prepared in example 1;

FIG. 7 is an X-ray diffraction pattern in which a represents an X-ray diffraction pattern of the Au-Fe nano alloy catalyst prepared in example 1, b represents an X-ray diffraction pattern of the Au-Fe nano alloy catalyst prepared in example 2, c represents an X-ray diffraction pattern of the Au-Fe nano alloy catalyst prepared in example 3, pure Au represents a standard card of Au element, pure Fe represents a standard card of Fe element, and Fe represents a standard card of Fe element₃O₄Represents Fe₃O₄A standard card of the table;

FIG. 8 is a transmission electron microscope image of the gold-iron nano-alloy catalyst prepared in example 1;

FIG. 9 is a transmission electron microscope image of the gold-iron nano-alloy catalyst prepared in example 2;

FIG. 10 is a transmission electron microscope image of the gold-iron nano-alloy catalyst prepared in example 3;

FIG. 11 catalytic reduction of CO₂In the graph, a tangle-solidup represents the catalytic reduction of CO by the gold-iron nano alloy catalyst of the example 6₂T. T.X represents the Faraday efficiency plot of CO for the catalytic reduction of CO by the gold-iron nano-alloy catalyst of example 7₂As a graph of the Faraday efficiency of CO,. diamond-solid.) represents the catalytic reduction of CO by the gold-iron nano-alloy catalyst of example 8₂● shows the catalytic reduction of CO by the Au-Fe nanoalloy catalyst of example 8, which is a graph of the Faraday efficiency of CO₂Graph of Faraday efficiency for CO, ■Catalytic reduction of CO with the gold-iron nanoalloy catalyst representing example 10₂Graph of faradaic efficiency for CO;

FIG. 12 catalytic reduction of CO₂The current density diagram of CO is shown, in the diagram, a-solidup part represents the catalytic reduction CO of the gold-iron nano alloy catalyst of the embodiment 6₂Is a current density graph of CO, t.t. represents the catalytic reduction of CO by the gold-iron nano-alloy catalyst of example 7₂Current density plot of CO,. diamond-solid.) represents the catalytic reduction of CO by the gold-iron nanoalloy catalyst of example 8₂● shows the current density plot of CO for the catalytic reduction of CO by the Au-Fe nanoalloy catalyst of example 8₂■ shows the current density diagram of CO in the catalytic reduction of CO by the Au-Fe nanoalloy catalyst of example 10₂The current density of CO is plotted.

Detailed Description