CN113463114A - Nano-alloy cubic hollow shell structure CO2Preparation method of electro-reduction catalyst - Google Patents

Abstract

Translated fromChinese

本发明公开了一种纳米合金立方空壳结构CO₂电还原催化剂的制备方法，将PdCl₂水溶液和CuCl₂•2H₂O水溶液混合分散在乙二醇中，加入L‑谷氨酸和8wt%的KOH的乙二醇溶液将溶液B的pH调节至11，加入商业多壁碳纳米管MCNTs得到悬浮液；将悬浮液热处理及干燥得到立方空心壳状结构PdCu‑CNTs电催化剂。本发明制得的合金纳米催化剂中的Pd、Cu之间的电子效应和协同效应同时也提高了电催化还原CO₂为CO的法拉第效率。

The invention discloses a preparation method of a nano-alloy cubic hollow shell structure CO₂ electroreduction catalyst. PdCl₂ aqueous solution and CuCl₂ •2H₂ O aqueous solution are mixed and dispersed in ethylene glycol, and L-glutamic acid and 8wt% are added. The pH of solution B was adjusted to 11 using ethylene glycol solution of KOH, and commercial multi-walled carbon nanotube MCNTs were added to obtain a suspension; the suspension was heat-treated and dried to obtain a cubic hollow shell-like structure PdCu-CNTs electrocatalyst. The electronic effect and synergistic effect between Pd and Cu in the alloy nano-catalyst prepared by the invention also improve the Faradaic efficiency of electrocatalytic reduction of CO₂ to CO at the same time.

Description

Nano-alloy cubic hollow shell structure CO2Preparation method of electro-reduction catalyst

Technical Field

The invention belongs to CO₂The technical field of preparation of an electro-reduction catalyst, in particular to a nano-alloy cubic hollow shell structure CO₂A preparation method of an electro-reduction catalyst.

Background

The mature carbon dioxide capture technology provides a stable carbon source for resource utilization, and abundant and cheap CO is supplied₂Directly converted into useful chemicals, can reduce the content of carbon dioxide in the air, reduce the influence caused by greenhouse effect, and can obtain products with higher industrial added value due to CO₂The chemical property is stable, the catalytic hydrogenation reduction needs to be carried out at high temperature and high pressure, and the reaction condition is harsh, so that the reaction condition is more moderate CO₂Electrochemical reduction, photocatalytic reduction and photoelectrocatalytic reduction technologies have been receiving much attention. Meanwhile, the technology can utilize clean energy such as solar energy and the like, can effectively relieve the pressure of increasing energy demand, and has become CO in recent years₂The hot spot of resource utilization research. Therefore, an efficient and stable electrocatalyst was developed for electrocatalytic CO₂One of the important problems to be solved in the technical field of reductive catalyst synthesis.

Recently, chemically, physically and biologically utilized CO has been studied₂The resource utilization is realized. And CO₂The resource utilization of the carbon dioxide is to convert the carbon dioxide into useful chemical products. In which CO is electrocatalyzed₂The reduction catalyst has better application potential and becomes a hot spot of research in recent years. The alloy hollow PdCu-CNTs have large specific surface area, can expose more active sites and have good CO₂RR activity, compared with cluster PdCu-CNTs, the alloy hollow PdCu-CNTs have better Faraday efficiency.

Noble metal nanoparticles are widely used as catalysts in many important fields of contemporary organic chemistry, fine chemistry, and fuel cells. The increasing price and storage of precious metals limits practical applications. To solve these problems, much research has been focused on improving the catalytic efficiency of the noble metal catalyst. Alloying of noble metals with non-noble metals (Fe, Co, Ni, Cu, etc.) is one of the effective methods to improve catalytic activity and selectivity, thereby reducing noble metal loading and reducing catalyst cost. Another strategy is to prepare catalysts with hollow metal nanostructures to achieve high catalytic performance and utilization efficiency, because they have a high specific surface area. In the past, some single-metal or bimetallic noble metal hollow nanospheres were prepared using more active metal nanoparticles as sacrificial templates. However, the complicated procedures and the strict reaction conditions limit the practical application of these methods. Therefore, a simple method for preparing hollow noble and non-noble metal alloy nanostructures is highly necessary. In this patent, hollow alloy nanocubes are prepared by a simple method. Multiwall carbon nanotubes (MWCNTs) were chosen as the support. Simple procedures and mild reaction conditions are advantageous for practical application of the method. And finally, carbon dioxide electrochemical analysis shows that the alloy cubic hollow PdCu-CNTs catalyst has excellent carbon dioxide electroreduction catalytic performance.

Disclosure of Invention

The invention solves the technical problem of providing the CO with the cubic hollow nano-alloy shell structure, which has the advantages of simple operation, mild reaction condition, high reaction efficiency and low energy consumption₂A preparation method of an electro-reduction catalyst.

The invention adopts the following technical scheme to solve the technical problems, namely, the nano-alloy cubic hollow shell structure CO₂The preparation method of the electro-reduction catalyst is characterized by comprising the following specific steps:

step S1: 0.5-1.5mL of PdCl 2mg/mL₂Aqueous solution and 0.245-1.334mL of CuCl 6mg/mL₂•2H₂Mixing and dispersing an O aqueous solution in ethylene glycol to obtain a solution A, then adding 16.67mg of L-glutamic acid into the solution A to obtain a solution B, fully stirring and uniformly mixing, then adjusting the pH value of the solution B to 11 by using an ethylene glycol solution of 8wt% KOH under the condition of vigorous stirring to obtain a solution C, then adding 5mg of commercial multi-walled carbon nanotubes (MCNTs) into the solution C, and carrying out ultrasonic treatment for 30min and stirring for 2h to obtain a suspension;

step S2: and (4) transferring the suspension obtained in the step S1 into a 25mL autoclave with a polytetrafluoroethylene lining, sealing, heating to 160 ℃ at a heating rate of 5 ℃/min, keeping for 6 hours, cooling to room temperature, centrifuging to obtain a product, washing the product with secondary water for three to four times, and drying the obtained product at 40 ℃ for 24 hours under a vacuum condition to obtain the cubic hollow shell-shaped structure PdCu-CNTs electrocatalyst.

Compared with the prior art, the invention has the following beneficial effects:

1. the PdCu-CNTs core-shell structure synthesized by the method has excellent carbon dioxide reduction performance, and the synthesis method is simple to operate, mild in reaction condition, high in reaction efficiency and low in energy consumption.

2. The PdCu-CNTs have a hollow core-shell structure, have a large specific surface area, are exposed in a large number of active sites, can be in better contact with electrolyte, and can effectively improve the electrocatalytic activity of the catalyst.

3. In the invention, glycol is used as a reducing agent, not only has the function of reducing, but also has the function of dissolving other reactants, L-glutamic acid is used as a guiding agent, and Pd is used as a reducing agent²⁺Coordinating with L-glutamic acid, and adding proper amount of MWCNTs and ethylene glycol. The complex may form an adsorption layer on the surface layer of MWCNTs by pi-pi conjugation, and then Pd²⁺Through the in-situ reduction of ethylene glycol onto MWCNTs, the PdCu-CNTs catalyst is formed.

4. The PdCu-CNTs catalyst with the cubic hollow shell structure synthesized by the method has the advantages of high specific surface area, increased active sites of the catalyst and improved carbon dioxide reduction performance due to the synergistic effect of Pd and Cu.

Drawings

FIG. 1 is a TEM image of the product obtained in example 1;

FIG. 2 is a TEM image of the product obtained in example 2;

FIG. 3 is a TEM image of the product obtained in example 3;

FIG. 4 is a graph showing electrochemical properties of the product obtained in example 1.

Detailed Description

The present invention is described in further detail below with reference to examples, but it should not be construed that the scope of the above subject matter of the present invention is limited to the following examples, and that all the technologies realized based on the above subject matter of the present invention belong to the scope of the present invention.

Example 1

Step S1: 1.322mL of 2mg/mL PdCl₂Aqueous solution and 1.334mL of CuCl 6mg/mL₂•2H₂Mixing and dispersing an O aqueous solution in ethylene glycol to obtain a solution A, then adding 16.67mg of L-glutamic acid into the solution A to obtain a solution B, adjusting the pH of the solution B to 11 by using an ethylene glycol solution of 8wt% of KOH under the condition of intensive stirring after fully stirring to obtain a solution C, then adding 5mg of commercial multi-walled carbon nanotubes (MCNTs) into the solution C, and obtaining a suspension by ultrasonic treatment for 30min and stirring for 2 h;

step S2: transferring the suspension obtained in the step S1 into a 25mL autoclave with a polytetrafluoroethylene lining, sealing, heating to 160 ℃ at a heating rate of 5 ℃/min and keeping for 6 hours, centrifuging to obtain a product after cooling to room temperature, washing the product with secondary water for three to four times, and drying the product at 40 ℃ for 24 hours under vacuum to obtain Pd₁Cu₁-CNTs electrocatalyst. 4mg of Pd prepared in this example₁Cu₁The CNTs electrocatalyst is dispersed in the dispersant, the mixed solution is ultrasonically homogenized and then coated on the surface of the conductive carbon paper electrode, the performance of the catalyst is measured by an electrochemical workstation by adopting an H-shaped electrolytic cell system, and the electrical performance test result is shown in FIG. 4.

Example 2

Step S1: 1.5mL of 2mg/mL PdCl₂Aqueous solution and 0.245mL of CuCl 6mg/mL₂•2H₂Mixing and dispersing an O aqueous solution in ethylene glycol to obtain a solution A, then adding 16.67mg of L-glutamic acid into the solution A to obtain a solution B, adjusting the pH of the solution B to 11 by using an ethylene glycol solution of 8wt% of KOH under the condition of intensive stirring after fully stirring to obtain a solution C, then adding 5mg of commercial multi-walled carbon nanotubes (MCNTs) into the solution C, and obtaining a suspension by ultrasonic treatment for 30min and stirring for 2 h;

step S2: transferring the suspension obtained in the step S1 into a 25mL autoclave with a polytetrafluoroethylene lining, sealing, heating to 160 ℃ at a heating rate of 5 ℃/min and keeping for 6 hours, centrifuging to obtain a product after cooling to room temperature, washing the product with secondary water for three to four times, and drying the product at 40 ℃ for 24 hours under vacuum to obtain Pd₃Cu₁-CNTs electrocatalyst. Collecting 4mg of BenshiPd prepared in example₃Cu₁The CNTs electrocatalyst is dispersed in the dispersant, the mixed solution is ultrasonically homogenized and then coated on the surface of the conductive carbon paper electrode, the performance of the catalyst is measured by an electrochemical workstation by adopting an H-shaped electrolytic cell system, and the electrical performance test result is shown in FIG. 4.

Example 3

Step S1: 0.5mL of 2mg/mL PdCl₂Aqueous solution and 0.74mL of CuCl 6mg/mL₂•2H₂Mixing and dispersing an O aqueous solution in ethylene glycol to obtain a solution A, then adding 16.67mg of L-glutamic acid into the solution A to obtain a solution B, adjusting the pH of the solution B to 11 by using an ethylene glycol solution of 8wt% of KOH under the condition of intensive stirring after fully stirring to obtain a solution C, then adding 5mg of commercial multi-walled carbon nanotubes (MCNTs) into the solution C, and obtaining a suspension by ultrasonic treatment for 30min and stirring for 2 h;

step S2: transferring the suspension obtained in the step S1 into a 25mL autoclave with a polytetrafluoroethylene lining, sealing, heating to 160 ℃ at a heating rate of 5 ℃/min and keeping for 6 hours, centrifuging to obtain a product after cooling to room temperature, washing the product with secondary water for three to four times, and drying the product at 40 ℃ for 24 hours under vacuum to obtain Pd₁Cu₃-CNTs electrocatalyst. 4mg of Pd prepared in this example₁Cu₃The CNTs electrocatalyst is dispersed in the dispersant, the mixed solution is ultrasonically homogenized and then coated on the surface of the conductive carbon paper electrode, the performance of the catalyst is measured by an electrochemical workstation by adopting an H-shaped electrolytic cell system, and the electrical performance test result is shown in FIG. 4.

The foregoing embodiments illustrate the principles, principal features and advantages of the invention, and it will be understood by those skilled in the art that the invention is not limited to the foregoing embodiments, which are merely illustrative of the principles of the invention, and that various changes and modifications may be made therein without departing from the scope of the principles of the invention.

Claims (1)

Translated fromChinese

1.一种纳米合金立方空壳结构电催化CO₂电还原催化剂的制备方法，其特征在于具体步骤为：1. a nano-alloy cubic hollow shell structure electrocatalysis CO_The preparation method of electroreduction catalyst is characterized in that concrete steps are:步骤S1：将0.5-1.5mL 2mg/mL的PdCl₂水溶液和0.245-1.334mL 6mg/mL的CuCl₂•2H₂O水溶液混合并分散在乙二醇中得到溶液A，随后将16.67mg的L-谷氨酸添加到溶液A中得到溶液B，充分搅拌混合均匀之后在剧烈搅拌条件下用8wt%的KOH的乙二醇溶液将溶液B的pH调节至11得到溶液C，然后将5mg商业多壁碳纳米管MCNTs添加到溶液C中，通过超声处理30min并搅拌2h得到悬浮液；Step S1: Mix and disperse 0.5-1.5 mL of 2 mg/mL aqueous PdCl₂ solution and 0.245-1.334 mL of 6 mg/mL aqueous CuCl₂ 2H₂ O solution in ethylene glycol to obtain solution A, followed by adding 16.67 mg of L- Glutamic acid was added to solution A to obtain solution B, and the pH of solution B was adjusted to 11 with 8 wt % KOH in ethylene glycol solution under vigorous stirring conditions to obtain solution C, and then 5 mg of commercial multi-walled Carbon nanotubes MCNTs were added to solution C, and a suspension was obtained by ultrasonic treatment for 30 min and stirring for 2 h;步骤S2：将步骤S1得到的悬浮液转移到25mL具有聚四氟乙烯内衬的高压釜中，密封，以5℃/ min的升温速率升温至160℃并保持6h，待其冷却至室温离心得到产物，将产物用二次水洗涤三至四次，将所得产物在真空条件下于40℃干燥24h得到立方空心壳状结构PdCu-CNTs电催化剂。Step S2: Transfer the suspension obtained in Step S1 to a 25 mL autoclave with a polytetrafluoroethylene lining, seal it, heat it up to 160 °C at a heating rate of 5 °C/min and keep it for 6 h, and then cool it to room temperature and centrifuge to obtain The product was washed three to four times with secondary water, and the obtained product was dried at 40 °C for 24 h under vacuum conditions to obtain a PdCu-CNTs electrocatalyst with a cubic hollow shell structure.

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